Management and Disposition of Excess Weapons Plutonium Reactor-Related Options (1995) / Chapter Skim
Currently Skimming:
Chapter 6: Comparing the Options
Chapter 6: Comparing the Options
Pages 250-396
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 250... ...
The array of options treated comprises: currently operating light-water reactors; currently operating heavy-water reactors; currently operating liquid-metal reactors; evolutionary light-water reactors; advanced light-water reactors; advanced liquidmetal reactors; modular high-temperature gas-cooled reactors; molten-salt reactors; particle-bed reactors; accelerator-based conversion systems; and immobilization with f~ssion-product wastes. The emphasis in these comparisons is on the options that we and the parent committee have concluded offer the greatest promise of reducing the security hazards associated with surplus WPu over the next 30 years or so the use of currently operating reactor types or evolutionary adaptations of them to incorporate WPu into spent fuel on a once-though basis, and vitrification of WPu with defense high-level wastes (HLW)
|
From page 251... ...
Given the importance of disposition of plutonium in Russia as well, however, several paragraphs at the end of each section in this chapter are devoted to a preliminary discussion of how the options in Russia compare by the same criteria. The panel believes that additional study rigorously comparing plutonium disposition options in Russia against the criteria outlined in this chapter is urgently needed.
|
From page 252... ...
GWe = gigawatt-electric. HM = heavy metal.
|
From page 253... ...
. The second row illustrates a case using an advanced annular fuel design to achieve very high burnup and a 50-percent plutonium destruction fraction starting from 4-percent WPu MOX fuel; this destruction fraction is considerably higher than those attained with more typical LWR parameters.
|
From page 254... ...
We then focus on the timing of different options, followed by discussions of the accessibility of the excess WPu during the course of the various disposition options and the degree of difficulty of recovering the excess WPu when they are complete. General Considerations Some general conclusions about the security dimensions of alternative approaches to disposition of WPu follow directly from consideration of the character of the threats likely to be of greatest concern (see Table 3-1~.
|
From page 255... ...
Nearly all disposition options other than indefinite storage as pits require processing and usually transportation of plutonium, in ways that could increase access to the material and complicate accounting for it, thus increasing the potential for diversion and theft. The biggest risks of these kinds involve the steps before the WPu has been either irradiated in a reactor or mixed with radioactive wastes.
|
From page 256... ...
Disposition options that entail use of MOX fuel in, and/or fuel reprocessing for, civilian power reactors could potentially encourage the expanded use of these approaches in ways that increase the vulnerability of reactor plutonium (RPu) to diversion for nuclear weaponry (including acquisition of weapons by countries that possess no WPu)
|
From page 257... ...
the WPu disposition mission is given high national priority with corresponding resources-as the panel recommends be done.2 2 We do not think that a decision to proceed with any of the advanced-reactor options could or should be made so quickly, but we chose to assume the same decision date for all the options in making these estimates in order to be able to compare, on an equal footing, the time requirements once a decision is made. The estimates given in Table 6-2 are in reasonably close agreement with those developed by the Fission Working Group Review Committee in the 1992-1993 Department of Energy Plutonium Disposition Study (Omberg and Walter 1993, Figure 5.1-8)
|
From page 258... ...
Complete development and design work on ALWR, select site and contrac tors, construct, test, and license plant: 199~2007. PLUTONIUM CONVERSION TO OXIDE AT MOX PLANT COMMENCES 2003; MOX FUEL LOADING IN REACTORS COMMENCES 2008 MHTGR or ALMRg Complete development and design work on reactors and fuel cycles, select site and contractors for co-located fuel fabrication facility and reactors, construct, test, and license: 199~2012.
|
From page 259... ...
The indicated operation date of 2013 is based on assuming a serious national commitment to achieving this, and thus is optimistic. The associated fuel fabrication facility assumed to be completable and licensable at least three years sooner than reactor, to permit accumulation of fuel for first full core by the time reactor is otherwise ready for operation.
|
From page 260... ...
In short, the time estimates in Table 6-2 are optimistic: while it is extremely unlikely that the disposition options considered here could be carried out more rapidly, it is very possible, even likely, that they will ultimately be carried out more slowly. Timing of plutonium disposition in Russia is even more uncertain than timing in the United States.
|
From page 261... ...
reactors for such fuel; but it would add a time requirement for negotiating the terms of such an arrangement. The pacing element in the use of existing reactors for WPu disposition might still be the licensing and construction or upgrading of MOX fuel fabrication facilities rather than reactor licensing, unless this fabrication took place in existing or planned European plants.
|
From page 262... ...
. MOX fabrication demand in this period, this might require the negotiation of arrangements and terms for the displacement, in European MOX fabrication plants, of the recycled civilian plutonium they would otherwise be using.3 This approach also would require overcoming political, environmental, and safeguards objections to transoceanic international shipment of U.S.
|
From page 263... ...
Conversion of pits to oxide is assumed to occur in connection with, and on the same time scale as, the MOX fuel fabrication or vitrification process.
|
From page 264... ...
ABWR, and minimizing plutonium transport would call for building it at the Hanford site (assuming FMEF provides the MOX fuel fabrication)
|
From page 265... ...
Russian CLWR, full MOX. If use of full-MOX cores with 4.0 percent WPu and burnup to 42 MWd/kgHM is feasible in WER-1000 PWRs, then four of these could load 3.28 tons of WPu per year, and the nominal 50 tons of surplus Russian WPu could be loaded in about 15 years (given a MOX fuel fabrication capacity of 100 MTHM/yr)
|
From page 266... ...
Assuming that MOX fabrication plant runs 1 yr accumulating 50 MTHM before loading first 33-MTHM one-third MOX core and keeping 4-month (= 17 MTHM) minimum reserve, MOX integrated inventory as heavy metal is (1 yr x 25 tons)
|
From page 267... ...
; and it would only shorten the duration of the campaign, once started, if MOX fuel fabrication capacity were expanded beyond what has been assumed here. Integrated inventories are not very sensitive to the choice of full-MOX versus one-third MOX cores (although of course the geographic dispersion of the inventories is likely to be sensitive to this choice)
|
From page 268... ...
(7) Construction of a new evolutionary LWR for WPu disposition, as might be done if political difficulties preclude using an already operating or now partly completed LWR, would also permit loading all of the 50 tons of WPu into a single reactor during its lifetime, at the cost of modestly delaying the start date for plutonium loading, delaying by about five years the completion of the campaign, and significantly increasing the pre-load oxide integrated inventory.
|
From page 269... ...
Ultimately, choices balancing these advantages and disadvantages of increasing the number of sites will have to be based on educated judgment; the panel is not aware of any defensible means by which these advantages and disadvantages can be quantified and rigorously compared. While it is true that thousands of assembled nuclear weapons are transported each year in the United States and the former Soviet Union, and that plutonium shipments in Europe are commonplace, it is nevertheless the panel's judgment that the advantages of limiting plutonium disposition to one or two sites outweigh the timing disadvantages of doing so-particularly as, in the United States, Russia, and some other countries, sites exist with several reactors at a single location, offering the possibility of limiting the time required for plutonium disposition while simultaneously keeping the number of separate sites to a minimum.
|
From page 270... ...
0.88 20 0.2 2 MOX fuel pellet, WPu 0.006 1 3 x 104 0.05 0 05 1 x 10-6 3 MOX fuel pellet, RPu 0.006 1 3 x 10= 0.05 1 2 x 10 5 3 LWRMOX fuel rod, WPu 2.5 410 0.1 0.04 0.03 1.4 x 104 4 LWR MOX fuel rod, RPu 2.5 410 0.1 0.04 0.7 3 x 10-3 4 LWR MOX fuel assembly, WPu 658 410 25 0.038 0.03 4 x 10-3 5 LWR MOX fuel assembly, RPu 658 410 25 0.038 0.7 0.08 5 MHTGR WPu fuel block 100 80 0.8 0.008 0.5 0.02 6 Irradiated LWR MOX fuel assembly, WPu 0.4 MWdlk~HM, 2 yr 658 410 23 0.035 38,000 4,500 7 10 yr 658 410 23 0.035 180 22 7 30 yr 658 410 23 0.035 79 9 7 100 yr 658 410 23 0.035 16 2 7 40 MWd/kgHM, 10 yr 658 410 18 0.027 18,000 2,200 7 30 yr 658 410 18 0.027 7,900 940 7 100 yr 658 410 18 0.027 1,600 190 7 50 MWdJlcgHM, 10 yr 658 410 9 0.014 23,000 2,800 7 30 yr 658 410 9 0.014 10,000 1,200 7 100 yr 658 410 9 0.014 2,000 240 7 MHTGR WPu fuel block irradiated to 580 MWd/kg~vI 2 yr 100 80 0.2 0.002 6,600 660 8 10 yr 100 80 0.2 0.002 1,800 180 8 30 yr 100 80 0.2 0.002 1,000 100 8 100yr 100 80 0.2 0.002 200 20 8 Borosilicate glass log with WPu and HLW small, 1.3%Pu,20%HLW 250 50 3 0.013 not calculated 9 large, 1.3% Pu, 20% HLW 2,200 300 22 0.013 5,200 900 9 same,+ 10 years 2,200 300 22 0.013 4,200 720 9 same, + 30 years 2,200 300 22 0.013 2,600 450 9 same, + 100 years 2,200 300 22 0.013 520 90 9 ABBREVIATIONS: Max = maximum Dim = dimension Conc= concentration aWPu assumed to contain 0.2 weight percent Am-241 (from initial 0.4 percent Pu-241, aged 14 years) , RPu, reactor plutonium, assumed to contain 4 weight percent Am-241 (from initial 9 percent Pu-241, aged 12 years)
|
From page 271... ...
3. Calculated as in note 2, for MOX fuel pellet with diameter 0.8 cm and length 1 cm, density 10.5 gm/cm3, 5.5 percent plutonium in heavy metal, and 0.2 percent Am-241 in plutonium.
|
From page 272... ...
Dose rates for 0.4-MWd/lcgHM irradiation at 10, 30, and 100 years scaled linearly with irradiation from 40-MWd/lcgHM results. To check the approximate method of notes 1 and 4, which we use elsewhere in this table when no detailed calculations are available, we here use the approximate method to recalculate, for comparison with the indicated "exact" calculation, the dose to be expected from LEU fuel irradiated to 33 MWd/kgHM.
|
From page 273... ...
/dis x 3,600 sec/h x 1.6 x 10-'3 J/MeV = 150 J/hr-kg . The mass energy-absorption coefficient for the 0.66 MeV gamma in glass with 1.3 percent plutonium is about 0.787 x 0.0293 + 0.20 x 0.033 + 0.013 x 0.078 = 0.031, where 0.0293, 0.033, and 0.078 cm2/g are the mass energy-absorption coefficients for 0.66-MeV gamma radiation in SiO2, tin, and plutonium, respectively (taking tin as representative of fission products)
|
From page 274... ...
It is our judgment that the chemical bamer is roughly comparable for the two options, in terms of the complexity of and technological sophistication needed for the steps required to separate plutonium from the two final waste forms. Overall, we rate both of these final forms as meeting the "spent fuel standard." Table 6-7 presents characterizations of the implementation-dependent barriers and overall vulnerability to different threats for the vitrification option and for a version of the current light-water-reactor option in which two 1,300-MWe LWRs using full-MOX cores load the nominal 50 tons of WPu over a period of 25 years (option CLWRb in Table 6-4~.
|
From page 275... ...
Nuclear-weapon pit 1 1 0 2 1 1 WPu oxide powder 1.1 1 1 2 0 1 MOX (WPu/U) powder 20 1 2 1 0 2 MOXfuel rod 25 1 2 1 2 2 MOXtuel assembly 25 1 2 1 3 2+ MOX spent fuel assemblya 35 2 4 4 3 4 WPu oxide in HEW log 50 1 4 4 4 4 NOTE: The basis for this characterization scheme is elaborated in Chapter 3 under "Specific Security Concerns and Threat Characteristics." a 40 MWd/kgHM.
|
From page 276... ...
Taking into account the modest advantage of the MOX options with respect to security of the final plutonium fond 7 This conclusion is compatible with the opinions of a number of safeguards experts consulted by the panel' who said that they considered MOX fuel fabrication plants more difficult to safeguard than a vitrification plant would be.
|
From page 277... ...
More advanced reactor options, such as the MHTGR and ALMR, would also not differ greatly, in their ratings in the framework of Table 6-7, from the Low case shown, assuming these advanced reactor types were used on a oncethrough basis. The MHTGR could gain 1 unit in the isotopic barrier rating when operated at very high burnup, and the co-location of fuel fabrication facilities with the reactors as would be possible with either of these reactors but also possible, in principle, with LWRs where new reactors or new fabrication capacity were sited to achieve this-would provide some gain in security; but we regard these potential improvements as insufficient to offset the large liabilities with respect to timing suffered by all the advanced reactor types, as discussed in the preceding section.
|
From page 278... ...
aVitrification: It is assumed that the repository is ready in 2015 and that the process of shipment of the logs to, and their emplacement in, the repository extends over a period of five years. bCurrent LWRs with Full-MOX Cores: It is assumed that there is only one MOX fabrication plant.
|
From page 279... ...
U.S. policy-makers, when making decisions on steps that could influence Russian plutonium disposition choices (such as provision of assistance for particular options, for example)
|
From page 280... ...
We consider, in turn, the costs of incorporating WPu into reactor fuel, the costs of using such fuel in currently operating reactors, the costs of using it in reactors now partly completed (which could be completed for the plutonium disposition mission) , the costs of building new reactors of evolutionary and advanced types and using them to process WPu-bearing fuel, and the costs of vitrifying the plutonium with defense HEW.
|
From page 281... ...
. We first consider, for specificity, a comparison between the use of conventional LEU oxide fuel in a PWR and the use of MOX fuel of comparable reactivity in the same reactor with the same burnu~i.e., same irradiation in thermal megawatt-days (MWd)
|
From page 282... ...
to uranium hexafluoride (USA; · enriching the UFO to the indicated U-235 concentration, · converting the enriched UFO to UO2; · fabricating the UO2 into fuel pellets, fuel rods, and fuel assemblies; · all the storage and transport steps associated with this chain, including delivery of the fuel assemblies to the reactor and their storage there until they are loaded into the core; and · the costs associated with ultimate disposition of the spent fuel after it leaves the nuclear reactor.'2 For the MOXfuel, the costs of · conversion of WPu metal to PU02; acquisition of depleted uranium and its conversion, if necessary, to UO2; mixing the oxides and fabricating the MOX into fuel pellets, fuel rods, and fuel assemblies; all the storage and transport steps associated with this chain, including delivery of the fuel assemblies to the reactor and their storage there until they are loaded into the core; and the costs associated with ultimate disposition of the spent filet after it leaves the nuclear reactor. " LEU and MOX fuels have somewhat different rates of change of reactivity with burnup.
|
From page 283... ...
We now turn to an activity-by-activity examination of the costs associated with the use of LEU and MOX fuels, beginning with LEU. LEU: Composition of the Total Costs The total costs per kilogram of heavy metal in fresh finely consist of the sum of terms obtained by multiplying, for each step in the filet production chain, the unit cost for the step (dollars per unit of activity in the step)
|
From page 284... ...
We follow the recent OECD fuel-cycle study (OECD 1992) in estimating other uranium losses in processing to be 0.5 percent in conversion to UFO, 1.0 percent in fuel fabrication, and negligible at other steps.
|
From page 285... ...
range for year 2000b 35-55 USDOE (1993a) Plutonium Disposition Study 65 OECD (1992)
|
From page 286... ...
. LEU: Fabrication Much of the difference in estimates of the costs of LEU fuel fabrication per kilogram of heavy metal appears to be due to the difference between PWR fuel and boiling-water reactor (BOOR)
|
From page 287... ...
To translate this operating cost into an equivalent contribution to the cost of fuel per kilogram of heavy metal, one must take into account both the number of electrical kilowatt-hours generated from 1 kgHM (which for our nominal PWR and 40,000MWd/kgHM burnup is 40 MWd/kgHM x 0.316 MW-electric/MW-thermal x l,OOO kW/MW x 24 fur/d = 303,000 kWh) and the way in which electric utilities calculate carrying charges on nuclear fuel.
|
From page 288... ...
Also, spent MOX fuel from a PWR would contain 23 percent residual plutonium versus about 1 percent in typical spent LEU fuel, and the associated criticality considerations may likewise dictate a lower packing density in the repository.
|
From page 289... ...
Because the uncertainties about ultimate disposition costs are so large, however, we choose not to add a figure of such questionable validity to the better-defined numbers for other elements of fuel costs. Instead we will present figures for LEU and MOX fuel costs less the costs of ultimate disposal, underlining here that if there is a difference between MOX and LEU in the omitted disposal costs it will be in favor of LEU.
|
From page 290... ...
} + {unit cost of MOX fuel fabrication [$/kgHM] } + {unit cost of ultimate disposition [$/kgHM]
|
From page 291... ...
The combined cost of acquiring depleted uranium and converting it to UO2 can hardly be more than $10/kgHM, and any error in this estimate cannot be important since it will assuredly be small compared to uncertainties in the other components of MOX fuel costs. MOX: Conversion of Plutonium Metal to PuO2 As noted above, it is appropriate to assign to the MOX fuel costs a contribution for conversion of plutonium metal to oxide, because some alternative schemes for disposition of the WPu-against which the MOX fuel option must be compared would not incur this cost.
|
From page 292... ...
The first of these figures is the GE estimate prepared for the U.S. Department of Energy's Plutonium Disposition Study (PDS)
|
From page 293... ...
These preoperational costs are often excluded or understated in cost estimates for a commercial operation (typically on the assumption that they are already "sunk" costs, or because it is assumed that they have been or will be covered by government) ; but, in assessing the costs to society of a WPu disposition program in a situation in which MOX fuel would not otherwise be being fabricated, the preoperational costs must be assigned to the disposition program.
|
From page 294... ...
In addition to the possibility of building MOX fuel fabrication facilities from scratch, there exists in the United States the possibility of completing the SAFLINE MOX fabrication line that now stands unfinished at the FMEF on DOE's Hanford reservation in Washington state.
|
From page 295... ...
Estimates of construction costs and operating costs for MOX fuel fabrication plants from the indicated references have been put on a consistent basis by the Reactor Panel using the following conventions: contingency factor = 25 percent of direct plus indirect construction costs (i.e., construction-cost estimates that did not include a contingency were multiplied by 1.25, and those that included a different contingency fraction, c, were multiplied by 1.25 / [l+c]
|
From page 296... ...
~ The central figure is the OECD study's "reference case" value of $1, 100/kgHM in 1991 dollars, explained in the report's Annex 6 and applicable during OECD's assumed operating period of 2007-2035, and here converted to 1992 dollars as $1,100 x 1/0.977 = $1,126. The figure is based on the assumption that MOX fuel fabrication will cost four times the report's $275/lcgHM figure for LEU fuel fabrication.
|
From page 297... ...
In constructing our own estimate of the cost of MOX fuel from the FMEF facility, we use a range of $100-$150 million in completion costs, which we take to be overnight costs; with an assumed four-year construction time, hence IDC multiplier of 1.19, the initial capital investment would be $ 119-$ 179 million. Since this facility is already on a federal site, we use only the lower fixed charge rate corresponding to no property tax or insurance charges, giving levelized-annualized capital charges of $9.6-$14.4 million/yr for a 30-year operating life, or $192-$288/lcgHM at 50 MTHM/yr.
|
From page 298... ...
(It may be presumed that storage at the plutonium conversion plant and MOX fuel fabrication plant is included in the estimates of the costs of these activities, but transport costs and any extra costs associated with the storage of MOX fuel after it leaves the fabrication plant but before it is loaded into the reactor core are not included.) The OECD study (1992)
|
From page 299... ...
The range of scales of MOX operations likely to be considered for a WPu disposition campaign therefore extends from about 25 MTHM/yr to about 100 MTHM/yr. For our reference-case MOX fuel, designed to deliver 40,000 MWd/MTHM with end-of-life reactivity equal to that of 4.4-percent enriched LEU after the same irradiation, we estimate the fuel-cycle costs at these scales of operation in the period from 2000 to 2030 to be as shown in Table 6-10, excluding repository fees.
|
From page 300... ...
The differential costs in Table 6-11 can be converted readily into annual costs and into net discounted present values of such cost streams for a full plutonium disposition campaign. For example, at a MOX fabrication rate of 50 MTHM/yr and the indicated plutonium loading of 4.8 percent in heavy metal, a 50-tons plutonium campaign would require 21 years of MOX fuel fabrication and corresponding MOX-based electricity generation, at an excess cost of $91.4 $27.4 million/yr (including fuel carrying charges)
|
From page 301... ...
At lower fissile content, and burnup, the economic comparison becomes even less favorable to MOX fuel; at higher fissile content and burnup, it becomes more favorable to MOX. The reason for this is that two of the main components of LEU fuel cost per kilogram of heavy metal uranium-acquisition and enrichment costs-increase sharply as the fissile content rises, while the cost of MOX fuel fabrication per kilogram of heavy metal, which is by far the largest component
|
From page 302... ...
30,000 MWd/MTHM 3.3% 3.6% U-235 WPu in LEU in MOX 2,120 10.5 1,080 800 500 5.3- 3.0 1.5 40,000 MWd/MTHM 4.8% WPu in MOX 2,200 8.2 5.3 50,000 MWd/MTHM 5.5% 6.0% U-235 WPu in LEU in MOX 1,780 2,280 6.8 Fuel cost, $/kgHM Fuel cost, $/MWh MOX penalty, $/kgHM MOX penalty, $/MWh 1,040 5.2 NOTE: Costs relate to PWRs fed by new MOX fuel fabrication plants paying property taxes and insurance and operating at 100 MTHM/yr. of MOX fuel cost in a situation where the plutonium metal is obtained free of cost, goes up only a little or not at all with plutonium loading.'9 The sensitivity of the cost comparison to fissile content is illustrated quantitatively in Table 6-12, where it has been assumed that the only component of MOX fuel cost, from a new fuel-fabrication plant, that varies with plutonium content is the cost of conversion of plutonium metal to oxide (taken to be $7/gPu at 100 MTHM and 5 percent plutonium by weight in heavy metal)
|
From page 303... ...
In the Plutonium Disposition Study ofthe Department of Energy (USDOE 1993a) , vendor estimates of"preoperational costs" (a category that includes research and development and plant testing as well as safety analysis and licensing)
|
From page 304... ...
Table 6-13 combines these estimates with the above-derived net discounted present value of the extra fuel-cycle costs as of start of operations, giving a range of central estimates of the net economic impact of using currently operating PWRs for WPu disposition extending from $450 to $2,100 million net discounted present value at start of operations, depending on whether FMEF or a new MOX fuel fabrication plant is used and on whether substantial modifications to permit l 00-percent MOX use are required or not. Variations in Reactor Type The economics of using WPu in reactors would be more attractive for reactors that require high levels of enrichment and derive high burnups from it.
|
From page 305... ...
On the MOX side, allowing $9/gPu for conversion to oxide and incremental storage and transport costs, as before, and $7/IcgHM for acquisition and conversion costs for 0.7 of depleted uranium per kilogram of heavy metal, leads to a corresponding MOX fuel cost of $7/kgHM + 1.015 x 200 gPu/kgHM x $9/gPu + $2,700/kgHM = $4,534/kgHM . Thus a cost advantage of about $6,000/kgHM is predicted for the use of plutonium in a MOX-fueled LMFBR, given cost-free WPu as the raw material (translating to $0.0074/kWh on a levelized basis, assuming r = 0.07, a four-year fuel cycle, irradiation of 100,000 MWd/MTHM, and thermal-to-electric conversion efficiency of 0.40~.
|
From page 306... ...
conclude that this facility could be modified to fabricate the needed quantities of MOX CANDU fuel for an overnight cost of $118 million, and that the operating costs would be about $64 million per year for the reference MOX fuel and about 20 percent more for the advanced fuel (which, however, would fuel four reactors rather than two and, thus generate twice as much electricity) , assuming plutonium metal-to-oxide conversion has been perfonned (and paid for)
|
From page 307... ...
and the minimization of shipping of MOX fuel (since WNP-1 is on the Hanford reservation where a MOX fuel fabrication capability is already partly in place, and WNP-3 is less than 200 miles from that site)
|
From page 308... ...
The U.S. government would pay all fuel-cycle and other operating costs (including, e.g., the costs of conversion of WPu to metal and of MOX fuel fabrication, and the costs of spent fuel disposal)
|
From page 309... ...
If MOX fuel production costs are $2400 ~ $400/kgHM (Ta~e 6-10, for 25-MTHM/yr throughput) and if the incremental costs of plutonium storage and transport are a relatively low $1/gPu (in light of minimal transport between fuel fabrication and reactor)
|
From page 310... ...
$0.063 ~ $0.006/kWh The range of $0.063 ~ $0.006/kWh is to be compared with our estimate from Chapter 3 of $0.050 ~ $0.015/kWh for the avoided costs associated with baseload electricity generation in connection with plutonium disposition in new plants. Combining the ranges based on the square root of the sum of the squares gives an expected net cost of $0.013 ~ $0.016/IcWh, or, stated another way, our 70-percent judgmental confidence interval for the net economic effect of the use of WNP-1 or WNP-3 for WPu disposition under the indicated assumptions, on a levelized-annualized basis, extends from a profit of $0.003/kWh to a loss of $0.029/kWh.
|
From page 311... ...
. If the high residual plutonium content in spent fuel associated with a 6.~-percent initial plutonium loading were considered problematic, so that both reactors needed to be used in order to complete the disposition campaign in 30 years or less, the up-front costs of the option would roughly double, but the per-kilowatt-hour costs would fall because of economies in scale in MOX fabrication.
|
From page 312... ...
The discounted present value in 1992 dollars, at the start of reactor operation, of the government's 30-year cost stream in this one-reactor case would be, under the central estimate, about $2.0 billion which is just the amount that the Isaiah Project proposes to provide the government. Building New Reactors for Plutonium Disposition In Phase I of the U.S.
|
From page 313... ...
The Peer Review Report also criticized the TRC report for inadequate analysis of cost uncertainties, insufficient attention to the implications of schedule differentials between more advanced and less advanced reactor types, failure to make comparisons with the economic costs of using existing reactors for the plutonium disposition mission, and failure to compare the costs of electricity generation using plutonium versus uranium fuels. While the Peer Review Report was criticizing a version of the TRC report different from the one publicly released, the panel believes that many of these criticisms apply to the final report as well.
|
From page 314... ...
Instead, we evaluated, for each of the five reactor types, the economics of a reactor array with sufficient capacity to process 50 tons of WPu within approximately one nominal reactor lifetime of 30~0 years from the start of reactor operation, using the contractor-analyzed fuel-cycle variant that we considered most representative of that reactor type's near-term plutonium disposition capabilities. (We chose the highest burnup variants that used the reactor type's "standard" fuel, which were the "spent fuel" variants for the PDR-600, System-80+, and ALMR, and the "destruction" variants for the ABWR and MHTGR.)
|
From page 315... ...
Rather than accepting the point-value estimates for these quantities provided in the PDS and accepting along with these estimates the inevitable doubts about whether the different contractors derived these estimates in comparable ways, with comparable degrees of optimism or conservatism- we have used the PDS estimates together with cost estimates for these fuel cycles and reactor types from other sources to develop ranges of values for use in our own economic calculations. Central estimates and ranges for MOX fuel-cycle costs were obtained in this way in "Weapons Plutonium Versus Uranium as Power Reactor Fuel" above.
|
From page 316... ...
6 ALMR) e System Performance Tl~ennal power, MWt/reactor 3,926 3,817 1,940 450 840 Net electric power, MWe/reactor 1,300 1,256 610 169 303 Conversion efficiency 0.331 0.329 0.314 0.376 0.361 Assumed capacity factor 0.75 0.75 0.75 0.79 0.75 Reactor output, 10' kWh/yr 8.55 8.26 4.01 1.17 1.99 Operating Mode Pu as percent of heavy metal 3.0 6.8 5.5 100.0 10.5 Average burnup, MWd/kgHM 37.1 42.2 40.0 580.0 69.1 Mean fuel life,yr 5.3 4.0 5.0 2.0 6.0 Fuel loaded, MTHM/reactor-yr 29.0 24.8 13.3 0.2 3.3 Pit loaded, kgPu/reactor-yr 870 1,685 731 224 350 Array Characteristics Reactors x yrs for 50 MT Pu 2 x 29 1 x 30 2 x 34 8 x 28 4 x 36 Array capacity, MWe 2,600 1,256 1,220 1,352 1,212 Array output, 109 kWh/yr 17.09 8.26 8.02 9.36 7.97 Fuel fabrication requirement MTHM/yr 58.0 24.8 26.6 1.8 13.3 Pu loaded, kgPu/yr 1,739 1,685 1,461 1,791 1,399 a GE ABWR: General Electric Advanced Boiling-Water Reactor.
|
From page 317... ...
The resulting central estimates and ranges for direct plus indirect costs of power-plant construction, as well as nonfi~el O&M costs, are presented and compared to the PDS point estimates in Table 6-15. In using estimates from the literature to develop our cons~uction-cost ranges, we have applied where appropriate an increment of 20 percent on direct plus indirect costs for first-of-a-kind costs, since the new reactors under consideration would indeed be first-of-a-kind if built for the immediate plutonium disposition need; the 20-percent figure is based on arguments and examples given in DOE costing-guideline documents (USDOE 1 988b, Delene and Hudson 1993~.
|
From page 318... ...
Based on examples given in DOE costing-guideline documents (USDOE 1988b, Delene and Hudson 1993) , we take first-of-a-kind costs, as would apply to the WPu disposition case we are considering, to be an increment of 20 percent on the indicated direct plus indirect costs; applying this factor and the two-unit, unit-cost learning factor of 1/2° ~ makes the two indicated estimates $1,560/kWe and $1,790/kWe for our 2 x 1,300 MWe case.
|
From page 319... ...
~ Advanced gas reactor: The PDS TRC estimates direct plus indirect costs at $2,789.4 million for an eight-module, 1,352-MWe power plant (USDOE 1993a, p.
|
From page 320... ...
Contingency The TRC for the DOE's Plutonium Disposition Study applied a contingency of 0.20 of direct plus indirect costs of a power plant's nuclear equipment and 0.15 of direct plus indirect costs of the ECA (Energy Conversion Area) for the evolutionary systems; 0.25 of nuclear reactor direct plus indirect costs and 0.20 of direct plus indirect costs of the ECA for the advanced systems; and 0.25 of direct plus indirect costs for fuel fabrication plants for both evolutionary and advanced systems.
|
From page 321... ...
and added to the operating costs. Fuel Costs Estimated costs of MOX fuel in $/kgHM for the evolutionary and advanced LWRs are taken from Table 6-10 for the three cases presented therefabrication at FMEF, paying no property tax or insurance, and fabrication at new plants both with and without property taxes and insurance at the scales most closely corresponding to the plutonium disposition arrays described in Table 6-14, and corrected for plutonium metal-to-oxide conversion and incremental transport and storage costs where the plutonium loading differs from the reference loading of 4.8 percent used in deriving the Table 6-10 figures.
|
From page 322... ...
Advanced Metal Reactor (GE/ANL ALMR) Array Characteristics Reactors x net MWe 2 x 1,300 1 x 1,256 2 x 610 8 x 169 4 x 303 Array annual TWh 17.09 8.26 8.02 9.36 7.97 MTHM/yr 58.0 24.8 26.6 1.8 13.3 kgPu/yr 1,739 1,685 1,461 1,791 1,399 yr for 50 MTPu 29 30 34 28 36 Power-Plant Construction Costs Array dir+indir, $/kWe 1,800~360 1,900~380 2,100~525 2,400:t720 2,500~750 Array overnight, $/kWe 2,133 2,252 2,594 2,964 3,088 Array w IDC, $/kWe 3,008 3,175 3,657 4,179 4,353 Array w IDC, M$ 7,820 3,987 4,461 5,650 5,276 Array pre-op, M$ 782 399 1,115 1,413 1,319 Array total, M$ 8,602~1720 4,386~877 5,577 t1,394 7,063~2,119 6,595~1,979 Power-Plant Array Capital Charges FCR, no tax, yr~i 0.0814 0.0806 0.0778 0.0824 0.0767 FCR, w tax, yr~' 0.1014 0.1006 0.0978 0.1024 0.0967 LACC '~o tax, M$/yr 701 353 434 582 506 LACC w tax, 873 441 545 723 638 c/kWh no tax 4.10~0.82 4.28~0.86 5.41~1.35 6.22~1.86 6.35~1.90 c/kWh w tax 5.10~1.02 5.34~1.07 6.80~1.70 7.72~2.32 8.01~2.40 Power-Plant Array Nonfuel O&M Costs O&M w/o D&D, M$/GWe-yr 75~11 80~12 90~14 85~13 90~14 O&M w/o D&D, M$/yr 208 94 1 10 1 15 109 Array D&D, M$ 447 197 298 330 326 D&D annuity, M$/yr 9.9 4.1 5.2 7.7 5.1 O&M w D&D, M$/yr 218~31 98~14 115~17 123~17 114~16 O&M w D&D, cAcWh 1.27~0.18 1.19~0.17 1.43~0.21 1.31~0.18 1.43~0.21 MOX Fuel Costs,i'$/lcgHM FMEF 1,900~300 2,500~400 2,500~400 NA NA New plant, ~o tax 2,600~400 3,400~500 3,400~500 38,000:t7,600 3,800~760 New plant, w tax 2,900 t400 3~800~500 3,800~500 44,000 t8,800 4,100~820 Pu conversion correction -202~66 284~90 99~31 0 0 Adj FMEFh 1,799~302 2,642~403 2,550~400 NA NA Adj ntw plant no tax 2,398~405 3,684~508 3,499~501 38,000~7,600 3,800~760 Adj new plant w tax 2,698~405 4,084~508 3,899~501 44,000~8,800 4,100~820 Fuel Cost Co',tribution to Electricity Cost, Including Repository Fee Carrying-charge factor 1.271 1.219 1.259 1.143 1.219 FMEF, c/lcWh 0.88~0.12 1.07~0.15 1.16~0.17 NA NA New plant no tax, cAcWh 1.13~0.17 1.45~0.19 1.56~0.21 0.93~0.17 0.93~0.17 New plant w tax, c/kWh 1 .26~0.17 1.59~0.19 1.73~0.21 1 .06:t0.19 0.99~0.1 8 Total Levelized Generation Cost, c/lcWh Reactor no tax, FMEFC 6.25~0.85 6.54~0.89 8.01~1.38 8.46~1.88 8.71~1.92 Reactor, ~,ew plant both tax 7.64:t1.05 8.13~1.10 9.96~1.72 10.10~2.33 10.43~2.42 Levelized Costs Net of Electricity Revenues ~ 5.0~1.5 c/kWh, M$/yr Reactor ~o tax, FMEFC 213~295 127~144 241~163 324~225 296~194 Reactor new plans both tax 452~313 258~154 398~183 477~260 433~227
|
From page 323... ...
Entries in this row for those reactors are based on a new fuel fabrication plant that does not pay property tax or insurance. ~ Not calculated because of lack of information on fuel costs with uranium fuel.
|
From page 324... ...
These are shown just for the high and low bounding cases on the low side, LW8s paying no property tax or insurance and supplied with MOX from the FMEF, which also pays no property tax or insurance, and, on the high side, reactors and new fuel fabrication plants all paying property tax and insurance. Net costs on a levelized-annualized basis are obtained by subtracting from the total costs the busbar value of the electricity generated in the course of plutonium disposition, based on a figure of $0.05 ~ $0.015/kWh (see "Issues and Criteria in Economic Evaluation of Alternatives" in Chapter 3 and "Completing Existing LWlRs" above)
|
From page 325... ...
(These calculations were done only for the LWRs; as discussed in "Completing Existing LWRs" above, the MHTGR and ALMR would be expected to show a net economic benefit from using free WPu in place of uranium, but we did not think that the estimates of uranium-based fuel-cycle costs available to us for these reactors were good enough to warrant a numerical calculation.) Discounted to the start of reactor operation, the central estimates of these LWR net costs relative to LEU operation are seen in the table to range from $500-$800 million in the case of reactors that do not pay property taxes and insurance, fed by MOX from FMEF, up to $1,000-$1,500 million for reactors that do pay these items, fed by new fuel fabrication plants that also pay them.
|
From page 326... ...
by considering that the power plant has a residual value at the end of the plutonium disposition campaign equal to the discounted present value at that time of the stream of electricity revenues from its future operation less the discounted present value of the stream of its future operating costs. (There is also a small correction for the postponement of the D&D costs of the power plant, but we neglect it here as small compared to the other uncertainties inherent in the calculation.)
|
From page 327... ...
surplus WPu into a fraction of the glass logs already scheduled to be produced at the Savannah River site as a means of immobilizing defense high-level radioactive wastes (see Chapter 5 and Table 6-3~. The panel believes that variations of the vitrification option that made less use of already planned facilities and operations would cost more, assuming that the full costs of constructing new facilities, and of producing and disposing of thousands of glass logs that would not otherwise be produced, were charged to the WPu disposition mission.
|
From page 328... ...
Because of the low material and labor costs in Russia, however, it may be that a kilogram of MOX fuel could be produced in Russia for less than the cost of an equivalent kilogram of LEU fuel in the West. This could create opportunities for largely private financing of plutonium disposition in Russia minimizing or eliminating the need for explicit government subsidies that do not exist in the case of U.S.
|
From page 329... ...
Some of these firms have already been discussing possible cooperation in MOX fabrication with Russia. (Both government and corporate policy-makers, however, will have to take into account the possibility of stiff commercial competition from a Russian MOX producer, once the plant was built and operational.)
|
From page 330... ...
The main ES&H issues posed by the MOX fuel and vitrification options were identified in "The Main ES&H Issues in Weapons Plutonium Disposition" in Chapter 3. In addressing those issues here, we begin with a synopsis of the characteristics of plutonium that bear on ES&H hazards and then discuss, in turn, the hazards of interim storage, transport, and processing of plutonium; the influence of the use of plutonium-based fuel on reactor safety; and the ways in which the MOX fuel and vitrification options may influence the ES&H characteristics of radioactive wastes.
|
From page 331... ...
by ingestion and inhalation for workers in nuclear industries and the Derived Concentration Limits for air and water (DCLA and DCLW) for public exposure, as promulgated by the Nuclear Regulatory Commission (last 4 columns of Table
|
From page 332... ...
Surface gamma doses calculated for uranium and plutonium metal at highest naturally occurring densities.
|
From page 333... ...
and on the time elapsed since the plutonium was separated (since the buildup of Am-241 is governed by the 14-year decay half-life of the Pu-241~. The gamma dose rates at the surface of metallic spheres of plutonium and uranium of different isotopic compositions are shown in the last column of Table 6-18.
|
From page 334... ...
as well as a secondary radiologic hazard from the fission products produced by the chain reaction; and it could represent, in some circumstances, a source of sufficient energy release to disperse the plutonium itself and any accompanying radioactive material more rapidly or widely than would be likely in the absence of a chain reaction. It must be emphasized that the kinds of criticality accidents to which we are referring here-that is, excluding the accidental detonation of a nuclear weapon (which is outside the scope of our responsibilities in this report)
|
From page 335... ...
nuclear-weapons complex, for example, have involved nuclear-energy releases ranging from a few megajoules to a few hundred megajoules, in contrast to about 85 million megajoules in a 20-kiloton nuclear weapon and perhaps 1 million megajoules in the criticality accident that set off the Chernobyl reactor disaster (National Research Council 1989, IPPNW/IEER 1992~. The nuclear energy releases in the nonreactor criticality accidents were enough, however, to produce potentially lethal radiation doses at a distance of several meters; and it is certainly possible to imagine circumstances c.g., with the reactants confined by soil or rock in a shallow burial site or deep geologic repository where the energy release could continue for long enough to become a significant driver of dispersal of radioactivity.
|
From page 336... ...
avoidance of criticality accidents resulting from excessive proximity and inadequate shielding of two or more pits in combination, as could occur in the course of bringing the pits into the facility, or as a result of insufficient care in designing the array in which they are to be stored, or as a result of subsequent unintended rearrangement of this array, for example, by flood, earthquake, or aircraft impact; (b) avoidance of accidental plutonium dispersal, particularly by fires in the storage facility (which could mobilize the plutonium metal in the pits as plutonium-oxide smoke)
|
From page 337... ...
Of these, the plutonium dioxide and the plutonium nitrate will require the greatest care to avoid accidental criticality and release modes that could produce significant worker exposures. (The fabricated MOX fuel is less problematic because (1)
|
From page 338... ...
central storage facility and the subsequent transport of the pits from there to a MOX fuel fabrication or vitrification plant (assuming that conversion to oxide takes place at these plants and not adjacent to the storage facility) , the obvious comparison is with transport of intact nuclear weapons.
|
From page 339... ...
Further study of the mobilizability of plutonium from borosilicate glass logs in severe transport accidents is warranted, however. In the case of the spent fuel option, it is reasonable to assume that conversion of pits to plutonium oxide would be co-located with other fuel fabrication steps, so that the remaining transport links would include only the transport of the fabricated fuel to the reactor sites if the reactors are not co-located with the fabrication plan~plus transport of the spent reactor fuel to any intermediate 34 According to Table 6-5, note 9, the logs to be produced at Savannah River will contain about 13 curies (Ci)
|
From page 340... ...
The spent fuel assemblies will have larger inventories of fission products and larger plutonium hazard potential per kilogram than the glass logs, and some of the fission products in the spent fuel may be in forms more volatile under accident conditions than any of the fission products in the glass logs.36 On 35 Recall from Table 6-1 that the amounts of plutonium in fresh MOX or MHTGR fuel as a fraction of the fuel matrix fall in the range of 1 to 5 percent by weight, with plutonium fractions in LMR fuels being several times higher. A gram of MOX fuel containing 4 percent by weight WPu and mobilized as fine airborne particulate matter would require a dilution volume of 1.6 x 10~m3 of air to reach the DCLA corresponding to a whole-body-equivalent annual dose of 0.5 millisieverts (50 millirem)
|
From page 341... ...
For the reference MOX fuel case (CLWR, 100-percent MOX core, 40 gWPu/kgHM in fresh fuel, 42-MWd/kgHM irradiation) , the disposition of 50 tons of WPu would utilize 2,700 fuel assemblies containing 1.25 x 106 kgHM, with a total mass, including cladding, spacers, and so on, of 1.8 x 106 kg, or about 2.5 times less than that of glass logs with their canisters.
|
From page 342... ...
. 39 Consider 15-year-old spent fuels that were irradiated to 42 MWd/kgHM and that contain 1.0 percent plutonium in the case of the LEU fuel and 2.6 percent plutonium in the case of the WPu-MOX fuel (see Table 6-1)
|
From page 343... ...
Hazards in Plutonium Processing Metal-to-Oxide Conversion Conversion of the plutonium metal pits to plutonium oxide would be required as an initial processing step for the vitrification option as well as for the spent fuel option with most reactor types LWRs, CANDUs, and MHTGRs using the current leading-candidate fuel formulation, and some LMRs. In the case of other HTGR designs using carbide fuels, and in the case of those LMR types that use metallic fuels in which plutonium is alloyed with other metals, the initial processing step would differ in details but would involve similar ES&H hazards.
|
From page 344... ...
Nonetheless, proper design and operation of the facilities, combined with adequate onsite fire-fighting capabilities, surely can hold the occurrence of fires and the mobilization of plutonium from those that do occur to very low levels. This is a matter that certainly will require the most careful attention from the designers, operators, and regulators of any plutonium disposition option.
|
From page 345... ...
The resulting need for special equipment and precautions in the fabrication of MOX fuel, as compared to what is involved in uranium fuel fabrication, is obvious, and this accounts for much of the difference in cost between MOX fuel fabrication and LEU fuel fabrication, as summarized above in "Weapons Plutonium Versus Uranium as Power Reactor Fuel." At the same time, the hazards at the fuel fabrication stage should be smaller in several respects than those encountered in plutonium metal-to-oxide conversion: once in oxide form, the plutonium is not flammable like the metal nor as prone to criticality accident as a plutonium nitrate solution; and, once diluted with uranium oxide, its radiologic and criticality hazards are further reduced.42 If, as we have concluded above, the ES&H hazards of plutonium metal-to-oxide conversion can be expected to satisfy the ES&H criteria set forth in this report, this should also be true of the additional plutonium-processing steps in MOX fuel fabrication. Further Plutonium Processing for the Vitrif cation Option In the case of the vitrification approach to plutonium disposition, the only plutonium-processing step beyond oxide production would consist of incorporation of the oxide into the mix of borosilicate glass and fission products either in the melter, or before the glass frit and fission products are introduced into the melter.
|
From page 346... ...
Determining how best to ensure that melter criticality problems do not contribute significantly to the ES&H hazards of plutonium disposition by the vitrification route is a technical issue that needs to be resolved before this disposition option is embraced. We do not think it will be so difficult to resolve, however, as to pose a significant obstacle to proceeding with this option if that 43 For example, a major fire in a vitrification plant being used for plutonium disposition might mobilize a similar quantity of plutonium to that mobilized by a major fire in a MOX fuel fabrication plant, but in the former case the extra hazard posed by the plutonium probably would be smaller than in the latter case because the fire in the vitrification plant would also mobilize significant quantities of fission products.
|
From page 347... ...
The plutonium that emerges from these reprocessing operations, moreover, will be more similar to reactor-grade plutonium than to weapons-grade plutonium in isotopic composition, hence will amplify the hazards ascribed above to MOX fuel fabrication with the weapons-grade material. On the other hand, plutonium recycle would reduce the amount of uranium mining and milling required to generate a given quantity of electricity, and hence would reduce the ES&H impacts of those operations.
|
From page 348... ...
These approaches appear to offer some advantages in the security realm compared to conventional reprocessing technology. Perhaps they will offer ES&H advantages, as well, but this will be difficult to confirm until these approaches have been further developed and tested.45 It is difficult, in any case, to compare the ES&H hazards of plutonium reprocessing and recycling for WPu disposition with the ES&H hazards that would be associated with civilian and military nuclear-energy activities in the absence of WPu disposition, because of the way in which disposition of WPu and the management of civilian plutonium are linked.
|
From page 349... ...
Reactor Safety Issues The potential influences on safeW of the use, in LWRs, of MOX fuel containing reactor plutonium were extensively studied in the United States in the 1970s, when large-scale use of this technology was being contemplated for commercial electric-power production (USNRC 1976~. These influences have also been studied in Europe (where considerable operating experience with onethird MOX cores in LWRs has been accumulated)
|
From page 350... ...
.47 47 In the most probable loss-of-cooling-accident scenarios, in fact, the main source of energy leading to overheating of the core after cooling fails is not the energy from the nuclear chain reaction, which usually would be promptly quenched. The problematic energy comes rather from "afterheat" the result of the radioactive decay of fission products, which diminishes over time according to their half-lives but cannot be shut offmore rapidly.
|
From page 351... ...
Quantitative analysis of these phenomena, however, combined with operating experience using MOX fuels in a number of countries, has shown that most LWR designs can accommodate MOX Mel made from reactor plutonium in at least one-third of their cores, without modification to the reactor, while remaining well within the capabilities of their control systems to safely limit reactivity excursions and the capabilities of their cooling systems to keep the fuel within safe thermal limits. As discussed in Chapter 4, the prospect of the availability of significant quantities of WPu for use as nuclear Mel following the end of the Cold War led, at the beginning of the 1990s, to a number of studies of the adaptability of LWRs to the use of MOX fuel made from this WPu rather than from the reactorgrade plutonium (RPu)
|
From page 352... ...
Any new LWR constructed for the purpose of WPu disposition could be designed to take a 100percent MOX core, as were the "evolutionary" and "advanced" LWR designs presented by vendors in the first phase of the U.S. Department of Energy's Plutonium Disposition Study (USDOE 1 993a)
|
From page 353... ...
If that is so, their use for WPu disposition seems unlikely to so alter their safety characteristics as to perturb significantly the safety of the whole nuclear-energy enterprise, all the more so because advanced-reactor types henceforth will probably all be designed from the outset to minimize any safety problems of plutonium use. Effects on Accident Consequences In the event of a large release of radioactivity as the result of a severe nuclear-reactor accident, the consequences generally will include relatively large doses of radiation (say, above 0.1 Sv or 10 rem)
|
From page 354... ...
354 PLUTONIUM DISPOSITION: REACTOR-RELATED OPTIONS Table 6-19 Contributions to Doses from Severe Reactor Accidents Nominal Severe-Accident 50-year Calculated LWR Estimated Population Dose (104 pers-Sv) Release Fractions Chernobyl Delivered Via: WASH NUREG Release Plume Ground Elements 1,400a 1~1 50b FractionsC Inhalation Dose Ingestion Kr,Xe 0.8-1.0 0.9-1.0 1.0 negl 0 0 I 0.4-0.9 0.2-0.9 0.2-0.6 0.5 1 1-5 Cs 0.4-0.5 0.05-0.8 0.
|
From page 355... ...
Based only on changes in the fuel composition, with release fractions for each element held constant, the substitution of MOX for LEU fuel would shrink the strontium dose about threefold while increasing that from plutonium, in the highest plutonium case, about fivefold. This would produce a net 10-percent increase in the total population dose.
|
From page 356... ...
Radioactive Waste Issues All options for the disposition of plutonium from surplus nuclear weapons will generate radioactive wastes of one or more types, and some options will affect the quantities or other characteristics of radioactive wastes that have been or will be produced by other military and civilian nuclear-energy activities. As a basis for surveying the radioactive waste implications of alternative approaches to plutonium disposition, the categories according to which radioactive wastes are described and regulated in the United States and the approaches for managing the wastes in these categories-can be summarized as follows (APS 1978; OTA 1985, 1989; Holdren 1992; OFR 1992, Pts.
|
From page 357... ...
are defined in the United States to mean all radioactive waste that is not spent final, HLW, or uranium mill tailings. LLW originate in nuclear-weapons-related activities, in commercial nuclear fi~el-cycle operations (e.g., uranium enrichment, nuclear fuel fabrication, reactor operation and decommissioning, spent fuel handling, and fuel reprocessing)
|
From page 358... ...
They amount to 100-150 m3/yr for a 1,200-MWe LWR with reprocessing and recycle (essentially entirely from the reprocessing and MOX fuel fabrication operations) , none from an LWR using LEU fuel once-through.
|
From page 359... ...
Implications for radioactive wastes of alternative options are considered more briefly. Spent Fuel and H`gh-Level Wastes: Dose Potentials Disposition of WPu by fabricating it into MOX fuel and irradiating that fuel once-through in power reactors of existing commercial types (e.g., LWRs or CANDUs)
|
From page 360... ...
Typical spent LWR fuel contains about 1 percent plutonium and typical spent CANDU fuel about 0.4 percent; the spent fuel under the MOX option for WPu disposition would contain, for reasonable initial plutonium loadings, from 2.5-5 percent plutonium if LWRs were used and 0.8-1.4 percent if CANDUs were used (see Table 6-1~. The amount of americium in discharged MOX fuel would also be greater than in LEU fuel at the same burnup.
|
From page 361... ...
Thermodynamic considerations suggest that the dissolution rates of the soluble fission products could be less than for LEU fuel. The higher actinide content of the MOX fuel as compared with LEU fuel does not contribute directly to the risk from the groundwater-intrusion/hydrogeologic-transport release mode, in the form of extra actinide contributions to the potential doses, because the rate of removal of actinides from the emplaced
|
From page 362... ...
For a repository to be considered satisfactory even for LEU fuel, however, the probability of intrusion by future miners needs to be very low, and given a suitably low intrusion probability the overall hazard from the repository is likely to be dominated by the fission products in the groundwater/hydrogeologic transport scenario which, as noted above, will not depend strongly on whether the spent fuel is MOX or LEU. In the case of the vitrification option, the disposition of 50 tons of WPu could be accomplished through the addition of 1.35 weight percent plutonium to 50/0.0135 = 3,700 tons of borosilicate glass, which would correspond to 2,200 of the 1,680-kg glass logs scheduled to be produced in the large melter at Savannah River.
|
From page 363... ...
1993~; if this is so, the use of this approach for the disposition of WPu would diminish the otherwise extant risks from defense HEW. Spent Fuel and High-Level Wastes: Criticality Issues As already noted, spent MOX fuel or plutonium-laden glass resulting from plutonium disposition would have higher plutonium concentrations than would the corresponding waste forms produced in the absence of plutonium disposition.
|
From page 364... ...
in which Pu-239 from spent PWR fuel, or from glass logs containing vitrified WPu, was hypothesized to separate from the accompanying materials and spread into surrounding rock in a way that would lead to supercriticality and explosive energy release of hundreds of tons of high-explosive equivalent (Bowman and Venneri 1995)
|
From page 365... ...
In a glass containing one or a few percent plutonium by weight, such as might be used for disposition of WPu, neutron multiplication would be held down by the presence of large quantities of neutron-absorbing boron in the borosilicate glass. Over the very long term, however, one must consider the possibility that groundwater could intrude into the repository, that the waste container might ultimately fail, and that in the presence of water, the boron and lithium in the glass might leach away more rapidly than the plutonium.
|
From page 366... ...
are 10-6 per year for silica and 4 x 10-7 per year for plutonium, for a waste glass containing 0.007 percent plutonium. From these data we would expect a 140-fold decrease in the net fractional dissolution rate of plutonium for a glass containing one percent plutonium.
|
From page 367... ...
One possibility would be to limit the plutonium concentration in the glass to a level low enough that the package would remain noncritical even if all of the boron and lithium in the glass leached away. Within the constraints of our study, we have only been able to begin exploring what the maximum concentration of plutonium that would be reliably noncritical in the worst case would be.56 In a dry system, glass logs with no boron or lithium would remain non-critical even with concentrations of 3 percent or more plutonium by weight (corresponding to 60 kg or more of plutonium in each log)
|
From page 368... ...
Gadolinium, for example, appears particularly promising, as it has a neutron-absorption cross-section much larger than that of boron, and a solubility believed to be comparable to that of uranium in the chemical environment expected in Yucca Mountain. Within the constraints of our study, we have not been able to explore the full range of such possibilities, or develop reliable information on the solubility of these potential additives, but we believe that this approach could be successful in alleviating long-term criticality concerns relating to plutonium in borosilicate glass.
|
From page 369... ...
Low-Level Wastes, TRU Wastes, and Tailings In the case of the once-through MOX spent fuel option, the primary influence of plutonium disposition on the character of the LLW that would otherwise be produced by the corresponding amount of electricity generation would be the production of TRU wastes from conversion of plutonium metal to oxide and from MOX fuel fabrication, to which steps there is no counterpart in a oncethrough LEU fuel cycle. In the 1992-1993 Plutonium Disposition Study of the U.S.
|
From page 370... ...
Of the 60 m3/yr, "a small fraction" was said to be TRU wastes. The small production of such wastes, compared to past experience with MOX fabrication, was attributed to minimizing the usual main sources of TRU waste production at MOX fuel fabrication plants, namely the chemical analysis lab and the scrap fuel area.
|
From page 371... ...
It may well be, for the vitrification option as well as for the MOX/spent fuel option, that the largest quantities of LLW and TRU wastes will come from the plutonium metal-to-oxide conversion step that is common to both options. With respect to uranium-mill tailings, use of the MOX/spent fuel option would obviate the need for the uranium mining and milling associated with 3060 1,200-MWe reactor-years of electricity generation, hence would reduce by (30-60 reactor-years)
|
From page 372... ...
And, while it may be argued that greatly improved performance in waste generation-if it should turn out to be achievable would be a great advantage in a reactor system intended for a major role in power production, the radioactive waste burdens associated with more conventional approaches to the disposition of 50 or 100 tons of WPu are not large enough to constitute an important incentive to develop advanced reactors and fuel cycles for the narrower and smallerscale purpose of plutonium disposition. Summary of Waste Issues Spent fuel resulting from the use of MOX in LWRs and borosilicate glass containing WPu as well as defense HLW would be different enough from spent fuel derived from LEU and the borosilicate-glass/HLW combination, respectively, that separate licenses would be required to certify these new forms as acceptable for waste disposal; it would not be possible to rely on the licenses and associated reviews required for commercial LEU spent fuel and currently planned HLW glass.
|
From page 373... ...
that borosilicate glass is less complex and easier to analyze than spent fuel in terms of repository behavior, which could be taken to imply that the possibility of reaching an earlier conclusion about its suitability constitutes a significant advantage of choosing the glass route for plutonium disposition We are not convinced that this distinction is either clear or significant-or if it were that it would remain so when the complication of additional plutonium content is imposed. Further, the intensive effort that has been mounted by DOE to design and evaluate the repository package for LEU spent fuel probably will give a licensing edge to the MOX/spent fuel option over the WPu/borosilicate-glass option.
|
From page 374... ...
Under the most optimistic assumptions that are defensible, loading of WPu into current-reactor types could begin between 2002 and 2004 and be completed between 2015 and 2025; loading of WPu into waste-bearing glass logs could begin around 2005 and be completed as early as 2013. The timing uncertainties in both cases-relating more to resolution of institutional issues in the reactor case and to resolution of technical issues in the vitrification case are bigger than the differences in the best-case point estimates we have provided; thus it would not be meaningful to say more than that the two sets of options are comparable.
|
From page 375... ...
(As discussed in the preceding sections, there can be substantial differences-in these respects and in othersamong variants within an option, depending for example on how many reactors at how many sites are employed, whether Mel fabrication facilities and reactors are co-located, and so on.) Advanced-reactor options do not appear to offer significant advantages, with respect to vulnerability of processing and transport steps, over the better variants among once-through current-reactor options, or over vitrif~cation.63 With respect to the security of the final plutonium forms that disposition options produce, we have concluded that meeting the "spent Mel standard" is both necessary and, for the decades immediately ahead, sufficient: if the WPu in its final form is not substantially more accessible for weapons purposes than the larger quantities of plutonium that will continue to exist in spent fuel from commercial electricity generation in this period, it will not represent a significant additional security hazard; but there is no great security advantage to be had from making the WPu much less accessible than the rest of the plutonium in commercial spent fuel, since the latter would then dominate the overall risk.
|
From page 376... ...
Although society might eventually decide to do this and might choose advanced reactor types for the purpose, transforming today's very dangerous stocks of surplus WPu to meet the spent fuel standard does not require advanced reactors and should not wait for them. Economics Estimates of the economic consequences of alternative reactor-related disposition options depend strongly on the assumptions that are made about a wide array of factors: the real interest or discount rate; the time required for design, construction, and licensing; the treatment of interest during this preoperational period; the market value of any electricity produced; whether the facilities are owned by the government or the private sector; and so on.
|
From page 377... ...
. ~ For the MHTGR and ALMR, the figures in this column correspond not to FMEF but to a new fuel fabrication plant that does not pay property taxes and insurance.
|
From page 378... ...
Although the central estimates in all cases considered correspond to net costs, our judgmental 70-percent confidence intervals include a possibility of profits from WPu disposition for the case in which currently mothballed, partly completed PWRs are completed for the purpose of plutonium disposition and these PWRs use MOX fuel from FMEF, and for cases when new, evolutionary LWRs are built for this purpose at government facilities (paying no property taxes or insurance) and use MOX from FMEF.
|
From page 379... ...
The main conclusions that emerge from this table and from the more detailed analysis in the section "Building New Reactors for Plutonium Disposition" are that: · most of the ES&H impacts of WPu disposition using either of these options can be expected to represent modest additions, at most, to the routine exposures to radiation and risks of accident associated with other civilian and military nuclear-energy activities underway in the United States; · there is no apparent reason that the activities involved in WPu disposition using either of these approaches should not be able to comply with all applicable U.S. ES&H regulations and standards; · while there are differences in detail in the ES&H challenges and risks posed by the two options in some of the activity categories e.g., a somewhat more complicated set of plutonium-handling operations for the reactor options than for the vitrification option, and a greater relative increase in plutonium content of the final waste form for the vitrification option than for the reactor options these differences do not consistently favor one class of options or the other, and none is large enough in relative or absolute teens to justify choosing one class of options over the other; · the ES&H issues to which the greatest attention ought to be given in the next phase of study of these options are (1)
|
From page 380... ...
Other Nuclear Energy and Nuclear-Weapon Activities Pit storage No difference Transport of pits or plutonium metal No difference Plutonium metal- No difference to-oxide con vers~on Storage of No difference plutonium oxide or nitrate MOX fuel fabrica tion Vitrification option lacks an equivalent step Transport of fresh Step does not occur in vitrifi MOX fuel cation option Irradiation in reactor Addition of plutonium to vitrification melt Transport of spent fuel or glass logs Geologic repository storage of spent fuel or glass logs Not more demanding than intactweapon storage already done on a larger scale Not more demanding than intactweapon transport already done on a larger scale No equivalent in current U.S. nuclearweapon or nuclear-energy practice, but technology for doing it safely is well established Less demanding than storage of wide array of plutonium forms and plutonium-contaminated materials in nuclear-weapon and nuclear-energy complexes No equivalent in current U.S.
|
From page 381... ...
The higher plutonium concentrations in spent fuel associated with using current-reactor/spent-fuel options for disposition, and the much higher plutonium concentrations in glass logs used for WPu disposition compared to those not so used, may add to the repository criticality problem. Nonetheless, the plutonium content in ordinary spent fuel is sufficient to necessitate very careful attention to the avoidance of repository criticality even in the absence of WPu disposition, and it is likely that the effort required to provide assurance against repository criticality for ordinary spent fuel will lead the way to measures that will provide this assurance for WPu-MOX spent fuel and for plutonium-bearing glass logs as well.
|
From page 382... ...
Plans to process tens of tons of plutonium at a particular site, or to introduce MOX fuel into certain reactors, can be expected to produce such interest. Added to the reactor-related opposition is the strong anti-DOE feeling in many communities.
|
From page 383... ...
In 1983, Congress barred the use of commercial fuel for nuclear explosive purposes. This legislation was specifi 66 In the fiscal year 1993 and 1994 budgets, for example, advocates of particular reactor options inserted Congressional "earmarks" directing that specific amounts of the money allocated to plutonium disposition be spent on studying particular reactor types, though DOE resisted this earmarking.
|
From page 384... ...
would be smoothed if there were explicit Congressional approval of the particular disposition options chosen. Given that Presidential Decision Directive 13 indicates that the United States does not encourage reprocessing of plutonium,67 Congressional approval would be particularly desirable if reactor options were chosen, to emphasize the national interest in accomplishing the plutonium disposition mission.
|
From page 385... ...
Were DOE to build a nuclear plant for this mission, or were DOE to buy and complete or take over an existing commercial nuclear plant, DNFSB could be asked to provide advisory oversight. It is not completely clear that DNFSB would be the appropriate agency, however, because such a plant would be for the purpose of generating electricity (using MOX fuel which happens to be fabricated using weapons material)
|
From page 386... ...
Major changes in the core, such as introduction of MOX fuel, would be reviewed by the NRC for potential effect on the safety of the reactor. Although a claim might be made that a license amendment would not be required,70 it would be prudent to assume that one would be necessary.
|
From page 387... ...
If the oversight process were handled by the DNFSB, its small size and unfamiliarity with regulation could make the process longer than if handled by the NRC. Nevertheless, the MOX fabrication facility still is likely to be the pacing item.7' Regulating Fuel Fabrication Facilities For the reactor options, fuel fabrication facilities would also be required, and these too would require regulation.
|
From page 388... ...
Presuming a vitrification facility was designed to provide adequate assurance of safety in these areas, gaining DNFSB approval for its operation should not pose special obstacles. Repository Regulatory Impacts Either spent MOX fuel or vitrified HLW glass would ultimately have to be disposed of in a geologic repository licensed by the NRC under regulations written to conform with other regulations written by the EPA.
|
From page 389... ...
Licensing and Plutonium Disposition in Other Countries If Canadian CANDU reactors were used for plutonium disposition, these would be regulated by Canada's Atomic Energy Control Board. As noted in Chapter 4, the regulatory environment in Canada tends to be less adversarial and involve more cooperation between regulators and utilities than is the case in the United States.72 As in the U.S.
|
From page 390... ...
DOE Plutonium Disposition Study. Windsor, Conn.: ABB-Combustion Engineering.
|
From page 391... ...
GE-ANL 1993: GE Nuclear Energy and Argonne National Laboratory. ALMR Plutonium Disposition StucJ;y.
|
From page 392... ...
WSRC-RP-93-755. Aiken, S.C.: Westinghouse Savannah River Company, 1993.
|
From page 393... ...
"German Utilities Bracing for MOX Fuel Cost Increases." Nuclear Fuel, January 6, 1992. Nuclear Fuel 1993: Mark Hibbs.
|
From page 394... ...
"Completion Cost Estimates for the WNP-1 and WNP-3 Plants." Letter to Matthew Bunn, Staff Director of the Committee on International Security and Arms Control plutonium study, National Academy of Sciences, Washington, D.C., October 14, 1993.
|
From page 395... ...
"Operating Experience with MOX Fuel Loaded Heavy Water Reactor." JournalofNuclear Science and Technology 30:78-88, 1993. Smith 1978: David R
|
From page 396... ...
U.S. Department Of Energy Plutonium Disposition Study, Peer Review Report.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.