Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials (1999) / Chapter Skim
Currently Skimming:
7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides
7 Environmental Protection Agency Guidances and Regulations for Naturally Occurring Radionuclides
Pages 106-156
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 106... ...
As discussed in chapter 2, the naturally occurring radionuclides of primary concern in radiation protection of the public include isotopes of uranium, thorium, and radium and their radiologically important shorter-lived decay products. EPA guidances and regulations reviewed in this chapter include those that apply either to TENORM or to naturally occurring radionuclides associated with operations of the nuclear fuel cycle, which are not included in TENORM as defined in this study.
|
From page 107... ...
GUIDANCE ON RADIATION PROTECTION OF THE PUBLIC EPA is responsible for developing guidance for all federal agencies on standards for radiation protection of the public. These standards apply to all specified controlled sources of exposure combined, excluding indoor radon, but do not apply to natural background radiation and to beneficial medical exposures.
|
From page 108... ...
per year for all controlled sources combined and the ALARA objective are satisfied, and the authorized limit for any source or practice normally should be a fraction of the dose limit for all controlled sources combined. The provisions listed above would apply to naturally occurring radionuclides, including TENORM, other than indoor radon, whenever exposures of the public are affected by human activities.
|
From page 109... ...
The reduction in the maximum allowable exposures was based on information on the risk per unit dose that was not available when the FRC guidance was developed and on a judgment about an upper bound on acceptable risk posed by exposure to all controlled sources combined (see chapter 5~. Finally, the separate dose limit for the gonads of average individuals in the FRC guidance, which was intended to limit the induction of severe genetic effects in exposed populations, would no longer be specified.
|
From page 110... ...
per year does not, by itself, provide acceptable radiation protection of the public; compliance with the ALARA objective also is a central tenet of radiation protection. Indeed, as a result of the establishment of authorized limits for specific sources or practices at a fraction of the primary dose limit and further vigorous application of the ALARA objective at specific sites, the average annual effective dose equivalent to individuals in exposed populations within 80 km (SO miles)
|
From page 111... ...
The primary dose limit proposed by EPA thus corresponds to about one-third of the average dose from natural background radiation, for which the estimated lifetime risk of fatal cancers is about 10-2. Although the average dose from exposure to natural background does not provide a justification for the primary dose limit for all controlled sources combined, it does provide a perspective for judging whether the dose limit for all controlled sources is reasonable (see chapter 5~.
|
From page 112... ...
The criteria that apply to naturally occurring radionuclides, including EPA's proposed federal guidance on radiation protection of the public discussed above, also are summarized in table 7.1. After He discussions of the guidances and regulations, the possibility of regulating NARM under TSCA or RCRA is discussed.
|
From page 113... ...
gross alpha-particle activity, including 226Ra but excluding radon and uraniums Proposed revisions of Concentration of 20 pCi/L for interim standards for 226Ra and 228Ra separately radioactivity in community drinking- Concentration of 20 ~g/L for water systems (EPA uranium 1997; 1991a) Concentration of 15 pCi/L for gross alpha-particle activity, excluding 226Ra, uranium, and 222Rnd Annual effective dose equivalent of 0.04 mSv from all beta- or gamma-emitting radionuclides, excluding 228Ra Comments Dose limit applies to all controlled sources of exposure combined, excluding indoor radon and beneficial medical exposures.
|
From page 114... ...
Based primarily on available effluent- control technologies. Releases during uraniumprocessing operations and from uranium mill tailings disposal sites before end of closure period must comply with dose constraint in 40 CFR Part 190 and concentration limits for liquid discharges in 40 CFR Part 440.
|
From page 115... ...
Based on goal of complying with relevant requirements under other environmental laws and achieving consistency with cancer risks corresponding to other laws and regulations (such as Safe Drinking Water Act and Clean Air Act)
|
From page 116... ...
GUIDELINES FOR EXPOSURE TO TENORM Guidance or regulation ! Quantitative criteria T Comments i| Standards for airborne Annual effective dose equivalent emissions of of 0.1 mSv for many DOE and radionuclides (40 CFR non-DOE federal facilities, but Part 61)
|
From page 117... ...
The dose constraint in the uranium fuel-cycle standards given above is essentially 5% of the primary whole-body dose limit of 5 mSv (500 mrem) per year for exposure to all controlled sources combined in the existing FRC guidance discussed earlier.
|
From page 118... ...
per year to the whole body or any organ for human-made, beta- or gamma-emitting radionuclides, but this standard does not apply to any naturally occurring radionuclides. The drinking-water standards for radionuclides were developed in accordance with requirements of the Safe Drinking Water Act.
|
From page 119... ...
This approach essentially represents another application of the ALARA objective to standard-setting itself. Although a risk assessment was performed in developing the standards, an a priori judgment about an acceptable risk posed by radionuclides in drinking water was not a consideration in establishing the standards.
|
From page 120... ...
and would be expressed in terms of the effective dose equivalent rather than the dose to the whole body or any organ. The Safe Drinking Water Act Amendments of 1996 contain two provisions that directly affect the proposed revisions of the drinking-water standards for radionuclides.
|
From page 121... ...
Those standards are concerned with control and cleanup of residual radioactive materials at or near inactive uranium- and thorium-processing sites and management of uranium and thorium byproduct materials at active processing sites. Only naturally occurring radionuclides are found in mill tailings, and the most important radionuclides of concern in protecting public health are radium, radon, and their decay products.
|
From page 122... ...
Compliance with the groundwater protection standard in Subpart D For management of uranium byproduct materials at active uranium processing sites, that is, for uranium-processing sites licensed by the Nuclear Regulatory Commission or Agreement States (states that enter into licensing agreements with the Nuclear Regulatory Commission)
|
From page 123... ...
123 Subpart E For management of thorium byproduct materials at active thorium-processing sites, that is, for thorium-processing sites licensed by the Nuclear Regulatory Commission or Agreement States: · Application of the standards for uranium, 222Rn, and 226Ra in Subpart D to thorium, 220Rn, and 228Ra, respectively, except that the flux standard for 222Rn during uranium-processing operations and before the end of the closure period does not apply to releases of 220Rn at thorium-processing sites during the same period. · During thorium-processing operations and before the end of the closure period, limits on annual dose equivalent to individual members of the public of 0.25 mSv (25 mrem)
|
From page 124... ...
An upper bound on the external dose corresponding to the concentration limits for 226Ra in soil can be estimated by assuming continuous external exposure; the presence of all decay products of 226Ra in equilibrium; indoor and outdoor residence times of 85% and 15%, respectively; a dosereduction factor during indoor residence due to building shielding of 0.7 (Nuclear Regulatory Commission 1977~; and external dose rates per unit concentration of 226Ra in surface soil as given in current federal guidance (Eckerman and Ryman 1993~. On the basis of those assumptions, the estimated annual effective dose equivalent from external exposure is about 0.5 mSv (50 mrem)
|
From page 125... ...
per year from all controlled sources combined in the existing FRC guidance on radiation protection of the public (FRC 1960) but is essentially the same as the primary dose limit of 1 mSv (100 mrem)
|
From page 126... ...
, storage, and disposal of waste, and they apply to naturally occurring radionuclides in the wastes. The standards for management and storage of spent fuel, high-level waste, and transuranic waste include the following provisions: · For facilities regulated by the Nuclear Regulatory Commission or Agreement States, and including all operations of uranium fuelcycle facilities covered by 40 CFR Part 190, limits on annual dose equivalent to individuals of 0.25 mSv (25 mrem)
|
From page 127... ...
and undisturbed performance of the disposal system, shall have a likelihood of less than one chance in 10 of exceeding specified values and less than one chance in 1,000 of exceeding 10 times the specified values. · For 10,000 years after disposal, undisturbed performance of the disposal system shall not cause the annual effective dose equivalent to individuals in the accessible environment from all potential exposure pathways to exceed 0.15 mSv (15 mrem)
|
From page 128... ...
Therefore, the groundwater-protection requirement for waste disposal clearly is not based solely on a judgment about acceptable risk posed by radionuclides in drinking water. EPA's analyses for undisturbed performance of waste-disposal systems also indicated that the groundwater-protection requirement should be reasonably achievable at well-chosen sites.
|
From page 129... ...
, EPA indicated a preference for a standard for management and storage in the form of a constraint on annual effective dose equivalent for individuals of 0.15 mSv (15 mrem) from all exposure pathways and a standard for disposal in the form of the same constraint on individual dose plus a separate requirement for groundwater protection that would be consistent with MCLs for radioactivity in drinking water established in 40 CFR Part 141 under the Safe Drinking Water Act.
|
From page 130... ...
established under other federal or state environmental laws, with federal drinking-water standards established in 40 CFR Part 141 under authority of the Safe Drinking Water Act specified as ARARs for cleanup of contaminated groundwater and surface water. · Other information to be considered (TBCs)
|
From page 131... ...
The process of arriving at negotiated cleanup levels at any CERCLA site thus clearly resembles applications of the ALARA objective to control of radiation exposures under authority of the Atomic Energy Act. A few contaminated sites are being remediated under authority of RCRA rather than CERCLA.
|
From page 132... ...
, EPA has indicated a preference that a site could be released for unrestricted use if the annual effective dose equivalent to individuals, assuming a residential land-use scenario, would not exceed 0.15 mSv (15 mrem) , which corresponds to a lifetime cancer risk of about 10-4; if levels of radon in existing and future structures would comply with the guidance on indoor radon discussed later in this chapter; and if levels of radioactivity in groundwater that is a current or potential source of drinking water would comply with drinkingwater standards (MCLs)
|
From page 133... ...
, and operating and inactive uranium mill tailings piles, except for inactive disposal sites licensed by the Nuclear Regulatory Commission. The standards issued in 1989 also applied to specified licensees of the Nuclear Regulatory Commission and Agreement States, including inactive uranium mill tailings disposal sites, nuclear power reactors, and facilities other than nuclear power reactors except for users of radionuclides only in the form of sealed sources.
|
From page 134... ...
Specifically, EPA was to determine a "safe" or "acceptable" risk to individuals or populations and an "ample margin of safety" below the safe or acceptable risk for protection of public health. The court ruled that technical feasibility and cost could not be the primary basis for the standards, as has often been the case with EPA standards developed under other laws, including the Atomic Energy Act, the Safe Drinking Water Act, and the Clean Water Act.
|
From page 135... ...
. Finally, although the court of appeals mandated considerations of acceptable risk, the resulting standards were shown to be reasonably achievable with existing effluent-control technologies (EPA 1989d)
|
From page 136... ...
· Standards for operations of uranium fuel-cycle facilities in 40 CFR Part 190 do not apply to TENORM, because they apply only to radioactive materials regulated under the Atomic Energy Act. · Standards for radioactivity in drinking water in 40 CFR Part 141 apply to TENORM from any source (and also include natural background)
|
From page 137... ...
These include the development of guidelines for disposal of wastes arising from treatment of drinking water and for the use and disposal of sewage sludge. Guidelines for Drinking-Water Treatment Wastes EPA has developed suggested guidelines for disposal of drinking-water treatment wastes that contain naturally occurring radionuclides (EPA 1994e)
|
From page 138... ...
. Deep-well disposal of radioactive waste below a USDW or shallow injection of nonradioactive waste is considered a Class V well, but no recommendations are made regarding disposal of drinking-water treatment wastes that contain naturally occurring radionuclides in Class V wells.
|
From page 139... ...
, and for concentrations approaching 74 Bq/g (2,000 pCi/g) a facility for low-level radioactive waste licensed by the Nuclear Regulatory Commission or an Agreement State under the Atomic Energy Act or a facility permitted by EPA or a state to dispose of discrete NARM.
|
From page 140... ...
for 226Ra plus 228Ra and 50 Gag for uranium for disposal in municipal landfills without the need for physical barriers or long-term institutional controls were based on the principle that the relatively high average risks posed by exposure to background radium and uranium in soil should not be allowed to increase by more than a small amount. EPA's suggested guidelines for disposal of radioactive waste arising from treatment of drinking water are not considered further in this report.
|
From page 141... ...
Regulation of TENORM under the Resource Conservation and Recovery Act RCRA is concerned, in part, with management and disposal of hazardous and nonhazardous solid waste. As in the case of TSCA, radioactive materials regulated under the Atomic Energy Act are excluded from regulation under RCRA, but the exclusion does not apply to NARM.
|
From page 142... ...
Table 7.2 also includes the lifetime risks resulting from exposure to natural background radiation, including indoor radon, and to indoor radon only. In converting effective dose equivalents to risk, the risk per unit dose is assumed to be 5 x 10-s per millisievert (5 x 10-7 per millirem)
|
From page 143... ...
b 0.7-9 x 10-3 4x 10-3 Annual effective dose equivalent from all controlled sources combined, excluding indoor radon, of 1 mSv (proposed federal guidance) 4x 10-3 Indoor gamma radiation level of 20 pR/h and indoor residence time of RSo/O ,~ 2x 10-3 Concentrations of 226Ra in soil of 0.2 Bq/g in top 15 cm and 0.6 Bq/g below 15 cm and continuous external exposure indoors and outdoors 9x 104 Annual dose equivalent to whole body of 0.25 mSv Sx 104 Annual effective dose equivalent of 0.15 mSv 4x 104 Annual effective dose equivalent of 0.1 mSv 2 x 10 ~ Concentration of uranium in drinking water of 20 ,ug/L 2 x 10 ~ Concentration of 226Ra in drinking water of 0.2 Bq/L 1 x 10Goal for cleanup of radioactively contaminated sites (CERCLA and NCP)
|
From page 144... ...
and transuranic waste (average risk in US population) aValues assume continuous exposure over 70 y and, unless otherwise noted, risk of fatal cancers per unit effective dose equivalent of 5 x 1O-s per millisievert (EPA 1994c; NCRP 1993a; ICRP 1991)
|
From page 145... ...
, which applies to all controlled sources combined except indoor radon and medical exposures, and in regulations for specific sources or practices, including operations of uranium fuel-cycle facilities (40 CFR Part 190) and management and disposal of spent fuel, high-level waste, and transuranic waste (40 CFR Part 191~.
|
From page 146... ...
per year for exposure over 70 years in EPA's proposed federal guidance on radiation protection of the public with the risk goal of 10-4 for cleanup of contaminated sites under CERCLA unless the fundamental difference in concept between the two is recognized. An example of the importance of a judicial mandate in establishing standards is provided by the standards for airborne emissions of radionuclides developed under the Clean Air Act.
|
From page 147... ...
The importance of the different bases of standards is illustrated by a comparison of EPA's proposed federal guidance on radiation protection of the public with the standards for radionuclides in drinking water. As indicated in table 7.2, the drinking-water standards for naturally occurring radionuclides correspond to lifetime risks of about 10-4, whereas the primary dose limit of 1 mSv (100 mrem)
|
From page 148... ...
developed under the Atomic Energy Act applies to all release and exposure pathways, whereas standards for radioactivity in drinking water developed under the Safe Drinking Water Act (40 CFR Part 141) apply only to a single environmental medium (water)
|
From page 149... ...
Differences in Considerations of Natural Background In some cases, the health risks corresponding to various guidances and regulations appear to be inconsistent essentially because some standards are concerned with exposures to naturally occurring radionuclides and others are not. Given the relatively high doses and risks posed by exposure to natural
|
From page 150... ...
per year, the assumed risk of fatal cancers has increased to 5 x 1O-s per millisievert (EPA 1994c, NCRP 1993a; ICRP 1991) , and a judgment by EPA that a lifetime risk of about 10- is an upper bound on acceptable risk for specific sources or practices has been increasingly incorporated into radiation standards on the basis of precedents in regulations developed under other environmental laws (such as the Safe Drinking Water Act, the Clean Air Act, CERCLA)
|
From page 151... ...
The considerable variability in risks embodied in the various guidances and regulations is explained in large part by differences in legislative and judicial mandates for setting standards, differences in the primary bases of standards, differences in the exposure situations to which the standards apply, differences in the population groups of primary concern, and differences in the accounting of natural background radiation. The important conclusion to be drawn from these discussions is that risks corresponding to different guidances and regulations should not be compared unless the bases of the standards and their applicability are well understood and the standards are interpreted properly.
|
From page 152... ...
The ALARA objective is implemented in part by establishing standards for specific sources or practices that limit doses for the exposure situations of concern to a fraction of the dose limit for all controlled sources combined, and further site-specific reductions in dose based on ALARA considerations
|
From page 153... ...
. Therefore, for the important case of releases from operating nuclear facilities, the doses and risks experienced by most members of the public are determined largely by vigorous application of the ALARA objective, but the primary dose limit and even, in many cases, the authorized limits for specific sources or practices at a fraction of the dose limit are rather unimportant in determining actual doses and risks.
|
From page 154... ...
SUMMARY This chapter has reviewed EPA's existing or proposed guidances and regulations that apply to control of routine exposures of the public to naturally occurring radionuclides. No particular distinction has been made in this review between standards for naturally occurring radionuclides associated with operations of the nuclear fuel cycle, which are developed under the Atomic Energy Act, and standards for TENORM, which are developed under environmental laws other than He Atomic Energy Act and are the main concern of this study.
|
From page 155... ...
The various standards for specific sources or practices apply to different exposure situations with different risks that are reasonably achievable. · Differences in the population groups of primary concern in developing standards, particularly whether the standards emphasize protection of maximally exposed individuals or protection of individuals who receive the average dose in exposed populations.
|
From page 156... ...
156 GUIDELINES FOR EXPOSURE TO TENORM specified in various guidances and regulations, application of the ALARA objective is the most important factor in determining acceptable risks. Therefore, to the extent that the ALARA objective is applied consistently to all exposure situations, all guidances and regulations would be consistent with regard to risks actually experienced, provided that it is also recognized that risks that are ALARA can vary considerably depending on the particular exposure situation.
|
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.