Radiochemistry in Nuclear Power Reactors (1996) / Chapter Skim
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8. SPECIAL RADIOCHEMICAL STUDIES
8. SPECIAL RADIOCHEMICAL STUDIES
Pages 159-188
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From page 159... ...
The daughter activities will either be washed out by the condensed steam or deposited on the turbine and heater surfaces. In order to estimate the parent decay and daughter buildup in the steam paths in the turbine, the transit time as well as the activity release rate must be known.
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From page 160... ...
If the transit time from the outlet of the reactor pressure vessel (RPV) to ache SJAE is known, the gaseous activity release rate at the RPV can be estimated.
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From page 161... ...
During a no-cleanup test, a number of practical operation parameters can be measured, such as the mass of reactor coolant, water cleanup halftime, iodine carryover, impurity input rate, etc. A typical example of no-cleanup test data is shown in Figure 8-2.
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From page 162... ...
Variation of Conductivity and pH Value in Reactor Water Dunng a No-Cleanup Test 84 RWCU _ TURNED RWCU RWCU OFF IN SERVICE IN SERVICE AT 0630 AT22 Kg/sec AT22 Kg/sec 1437 -1501 cry 2.2 ~· ( - ~ ·/ _ -/ '/ · - 5 ·Y \ CONDUCTIVITY INCREASED .
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From page 163... ...
Variation of Reactor Water Conductivity with RWCU Returriing to Service 3-5 6
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From page 164... ...
(1C -e-Xt) active nuclide produced during normal operation activation of parent nuclide input to reactor water during normal operation.
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From page 165... ...
140 120 100 ~80 z o E z LL z 60 o c: 40 20 o O Na-24, MEASURED A\ Cl-38, MEASURED MODEL CALCULATION, Na-24 l MODEL CALCULATION, Cl-38 O / / / O / O / O cot// ~I I I I I I / O ~ / / O d // .o / _ ~ 0 10 20 0 10 20 0 10 3/8 4/8 5/8 CLOCK TIME Figure 8-4. Variation of Na-24 and C1-38 Concentrations in Reactor Water during a No-Cleanup Test 8-7
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From page 166... ...
When the RWCU system is removed from the service 'Bc=0 in Equation 3-23, the iodine concentration will increase and reach a higher steady state concentration, Cnc (Figure 8-5) , Cnc- Ai (WLi + pi From the ratio of ci cnc _ Hi + 13c + Us Li + As _ = ps and the iodine carryover ~ can be calculated 8=0s F where all symbols have been defined in Section 3.2.3.
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From page 167... ...
100 10 1.0 1- 134 1 1 1/ 1 1 1 1 1 1 0 10 20 0 4/8 1 JO O ~O to Hi, =~ 1 - 135 0 1- 133 ~0 o ~o o 1- 131 3/8 10 20 0 5/8 CLOCK TIME 10 20 Figure ~5. Vanation of Iodine Activity Concentrations in Reactor Water during a N - Cleanup Test ~ 9
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From page 168... ...
are also observed after shutdown, but in some cases, up to 70% of iodine activities have been reported when H2O2 is added to the coolant. S.3.2 Chemical Forms of Radioiod~ne In BWR Coolants The chemical forms of radioactive iodine in reactor water have been measured in a number of reactors during normal operation and during shutdown.(2)
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From page 169... ...
~ 5/1987) 95 5 <1 <1 During Reactor Shutdown Nine Mile Point-1 ~ 4/1973)
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From page 170... ...
It is recommended to reduce the I2 in organic phase to I- for activity counting with 100 mL water containing sufficient Na2SO3.
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From page 171... ...
tests in three reactors, the IO3fraction was found substantially decreased as expected when the reactor water chemistry was switched to more reducing HWC conditions by hydrogen gas addition to suppress the water radiolysis in the coolant.
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From page 172... ...
The apparent aging of the gaseous iodine species in the offgas is probably due to the delay incurred between the iodine deposition on the material surfaces in the steam/turbine system and the subsequent formation and release of organic species. The true mechanism of organic iodine formation in the steam/turbine system is probably related to the production of 8-14
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From page 173... ...
12/1972 88 3 8 Monticello 7/ ~ 974 93 4 3 Table S-3 CHEMICAL FORMS OF IODINE ACTIVITIES IN BWR OMEGAS (%) Reactor Date Iodine HIO Organic Particulate Oyster Creek 1973*
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From page 174... ...
In a study on the surface effects in the transport of airborne radioiodine, Pelletier(l°) has reported up to 12% of the iodine originally released as I2 in 80% humidity air in contact with galvanized steel at ambient temperatures was converted to organic form in a few days.
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From page 175... ...
it is assumed that all of the "insoluble" transuranic elements appear in the coolant in the same proportion as they appear in the fuel and in amounts consistent with the insoluble fission products (Zr-95, Ru-106, Ce-141, and Ce-144) present in the coolant.
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From page 176... ...
This phenomenon can be explained by assuming that the average core burnup is always lower than the burnup of a particular fuel bundle from which the activity is released into the coolant. An important application of the relationship between the alpha activity and the insoluble fission products activities in the crud sample is that it is thus possible to estimate the alpha activity in the water sample or radwaste samples (Section 7)
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From page 177... ...
Table 13-6 RATIOS OF TOTAL ALPHA ACTIVITY TO INSOLUBLE FISSION PRODUCTS IN REACTOR WATER :~ , (103)
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From page 178... ...
Variation of Cm-242 to Zr-95 Activity Ratio in Coolant as a Function of Average Core Burnup 3-20
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From page 179... ...
In order to achieve a high precision and accuracy of flow measurement, there are a number of parameters that should be carefully determined during a measurement. These parameters are: (1 ~ Activity concentrations in the reference solution and water samples.
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From page 180... ...
~ Preparation of the Na-24 Reference Solution The reference solution is prepared by dissolving an irradiated Na2CO3 or NaNO3 containing ~ 200 mCi Na-24 in an appropriate container with dilute acid and demineralized water (total volume is about 2 liters)
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From page 181... ...
The exact mass of sample processed through the filter poles is determined by collecting the filter effluent in tared containers and reweighing. The filter holder is a Millipore high pressure filter holder similar to that used in the regular corrosion product sample solution.
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From page 182... ...
The individual fuel rods and the fuel assemblies are fabricated with exceptional care, to preclude the escape of fission products through even minor cladding defects. However, with such a large number of fuel rods it is possible for cladding failure to develop during an operating cycle.
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From page 184... ...
It takes the advantage of high sensitivity of measuring the gaseous fission product activity released from cladding defects under partial vacuum in the sipping container. The vacuum-sipper containers are designed so that they can be installed in the control-rod-blade storage rack in the fuel pool, or on the guide rod inside the BWR reactor cavity.
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From page 185... ...
The trapped air is then isolated and the space evacuated through a scintillation detector. The remaining low pressure gas volume is then recirculated through the monitor and back to the can for a predetermined time (3-5 min)
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From page 186... ...
Counting electronics Service air . ~ _ Lid actuator r it_ _ ~ ~Recorder Dryer VaCuum pump L ~ 1 1 T ~ Water trap To fue/-poo/ cleanup system , ~ | Scintillation I detector Eductor ~~~ Demineralized or condensate water n''Bubb/e,' ; ~ detector T I/ent 1 1 ~ 1 ~ Sipping container Figure 8-8.
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From page 187... ...
S Gilbert, "Qualification of the Na-24 Tracer Method for Feedwater Flow Nozzle Calibration", NEDM-12454 (September 1973~.
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