ML20199E766
| ML20199E766 | |
| Person / Time | |
|---|---|
| Issue date: | 01/29/1998 |
| From: | Greeves J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Simon S NATIONAL RESEARCH COUNCIL |
| References | |
| REF-WM-3 NUDOCS 9802020245 | |
| Download: ML20199E766 (4) | |
Text
..
Dr. Steven L. Simon Study Director, Drinking Water
. Board on Radiation Effects Research National Research Council 2101 Constitution Avenue, NW Suite 342 Washington, DC 20418
Dear Dr. Simon:
Enclosed is the December 12,1997, letter from Nuclear Regulatory Commission Chairman Shirley Jackson to Environmental Protection Agency Administrator Carol Browner concerning EPA's guidance entitled " Cleanup Levels for CERCLA (Compehensive Environmental Response, Compensation, and Llability Act of 1980) Sites with Radioactive Contamination." This letter is provided as requested by the National Research Council's Committee on Evaluation of EPA Guidelines for Exposure to Naturally Occurring Radioactive Materials. Call me at (301) 415-7437 if you have any questions or comments on this letter, Sincerely,
[0riginalsignedby]
John T. Greeves, Director Division of Waste Management Office of Nuclear Material Safety and Safeguards Enclotuis December 12,1997 letter cc:
Kevin Crowley, NAS Lawrence Weinstock, EPA /ORIA DISTRIBUTION:
Central File e NMSS r/f DWM r/f EDO r/f LLDP r/f MKnapp VHolahan HNewsome FCameron KStabtein MBell JHokmich RBangart FCardile SMcGuire L (d 8
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YES 1 NO _ Category: Proprietary _ or CF Only _
- ACNW:
YES 1 NO _
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YES _ NO 1 Delete file after distribution: Yes No 1
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t Dr. Steven L. Simon Study Director, Drinking Water
. Board on Radiation Effects Research National Research Council 2101 Constitution Avenue, NW Suite 342 Washington, DC 20418
Dear Dr. Simon:
Encloseo is the December 12,1997, letter from Nuclear Regulatory Commission Chairman Shirley Jackson to Environmental Protection Agency Administrator Carol Browner concerning EPA's guidance entitled " Cleanup Levels for CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act of 1980) Sites with Radioactive Contamination.' This letter is provided for your information. Call me at (301) 415 7437 if you have any questions or comments on this letter.
Sincerely, John T. Greeves, Director Division of Waste Management Office of Nuclear Material Safety e.d Safeguards
Enclosure:
December 12,1907 letter cc:
Kevin Crowley, NAS Lawrence Weinstock, EPA /ORIA Vicki Lloyd, EPA /ORIA John Karhnak, EPA /ORIA Stephen Luftig, EPA /OERR Loren Setlow, EPA /ORIA DISTRIBUTION' Central File NMSS r/f DWM r/f EDO r/f LLDP r/f MKnapp VHolahan HNewsome FCameron KStablein MBell JHolonich RBangart FCardile SMcGuire RJohnson CPaperiello CJones MFederline CTrottier DOCUMENT NAME: S:\\DWM\\LLDP\\ PAS \\NAS.LTR OFC LLDP LLDR/id LLDPy L DWM PSobe([I RNkob JMey NAME JGreeves DATE 1M7/98 1/M/98 1/ M/98 -
1/
/98 OFFICIAL RECORD COPY PUBLIC:
YES.x.NO _ Category: Proprietary _ or CF Only _
ACNW:
YES.x.No _
IG:
YES _ NO.x.
Delete file after distribution: Yes _ No.x.
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January 29, 1998 Dr. Steven L. Simon Study Director, Drinking Water Board on Radiation Effects Research National Research Council 2101 Constitution Avenue, NW Suite 342 Washington, DC 20418
Dear Dr Simon:
Enclosed s the December 12,1997, letter from Nuclear Regulatory Commission Chairman Shirley Jackson to Environmental Protection Agency Administrator Carol Browner concerning EPA's guidance entitled "Citanup Levels for CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act of 1980) Sites with Radioactive Contamination." This letter is provided as requested by the National Research Council's Committee on Evaluation of EPA Guidelines for Exposure to Naturally Occurring Radioactive Materials. Call me at (301) 415 7437 if you have any questions or comments on this letter.
Sincerely, John T. Greeves, Director Division of Waste Managemen'.
Office of Nuclear Material Safety and Safeguards
Enclosure:
December 12,1997 letter cc:
Kevin Crowley, NAS Lawrence Weinstock, EPA /ORIA
I
't Dr. Steven L. Simon Study Director, Drinking Water Board on Rsdiation Effects Research National Research Council 2101 Constitution Avenue, NW Suite 342 Wasliington, DC 20418
Dear Dr. Simon:
En:losed is the December 12,1997, letter from Nuclear Regulatory Commission Chairman Shirley Jackson to Environmental Protection Agency Administ.ator Carol Browner conceming EP Als guidance entitled " Cleanup Levels fer CERCLA (Comprehensive Environmental Response, Compensation, ar.d Liability Act of 1980) Sites with Radioactiva Contamination." This letter is provided as requested by the National Research Council's Committee on Evaluation of EPA Guidelir.ss for Exposure to Naturally Occurring Rt.dioactive Materials. Call me at (301) 415-7437 if you have any questions or comments on this letter.
Sincerely,
[0riginal signed by]
John T. Greeves, Director Division of Waste Management Office of Nuclear Material Safety and Safeguards
Enclosure:
December 12,1997 letter cc:
Kevin Crowley, NAS Lawrence Weinstock, EPA /ORIA DISTRIBUTION:
Central File NMSS r/f DWM r/f EDO r/f LLDP r/f MKnapp VHoiahan HNewsome FCameron KSta6tein MBell JHolonict, RBangart FCardite SMcGuire RJohnson CPaperiello CJones MFederline CTrottier DOCUMENT NAME: S:\\DWM\\LLDP\\ PAS \\NAS.LTR l
- see previous concurrence OfC LLOP LLDP LLDP DWNC.( /
NAME PSobellbg*
RNelson*
JHickey*
hbeves DATE 1/29/98 1/29/98 1/29/98 1/ N/98 OFFICIAL RECORD COPY PUBLIC:
YES 1 NO _ Category: Proprietary __ or CF Only _
ACNW:
YES 1 NO _
IG:
YES _ NO 1 Delete file after distribution: Yes _. No 1
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION a
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12, 1997 i
cuase m The Honorable Carol M. Browner Admirustrator U.S. Environmentd Prohmtlon Agency V:2:z, D.C. 20400
Dear Adminstrator Browner:
in August 1997, we received a copy of OSWER No. g200.418 entitled " Establishment of Cleanup Levels for CERCLA Sites with Radioactive Contamination." The stated purpose of the document is to provide clarifylog guidance for what the U.S. Environmersal Protection Agency (EPA) esserts would establish protective cleanup levels for radioactive contamination at Comprehens! 3 Environmental Response, Corr;ensation, and Liability Act of 1980 (CERCLA) sites.
A speci6c point mado in the CERCLA guidance is EPA's determir, dion that the dose limits in the U.S. Nuclear Regulatory Commission's (NRC) final rule on " Radiological Criteria for Uconse Termination * (issued July 21,19971 generally will not provide a protective basis for establishing preliminary remediation goals for cleanups et CERCLA sites and that NRC sites cleaned up to the 25 mrom/yr all pathways criterion will have to be remediated further to meet the CERCLA and National Oil and Hazardous Substa.9ces Pollution Contmgency Plan requirements to be protective. This guidance also seeks to impose the 15 mrom/yr and separate groundwater requirements contained in the EPA drsft cleanup rule vnthdrawn by.
EPA from the Offlee of Management and Budget in December 1996. These statements are of specific concem to us for several reasons.
Rrst, this appreidi results in the imposition of the CERCLA risk ronge on radionuclides without the informed and open discussions that would be part of the rulemaking process to establish such radiation protection standards-a process which NRC recently w,TC1 Secondly, the Commission's final rule is based on considerations of risk, radiation protection principles, national and intomationsi standards, and costs compared to m benents of cleanup. In leeuing the rufe, we concluded that thu final rule not only protects public health and safety, but aien e..ateiishes the framework to address the Imited number of difRcult cases which would odierwies require asse by caos exemptions. We behove this approech not only achieves cost effeedve reguistion and adequate protection of public health and estety and the erwironment, but also is based on sound policy.
The third reason for our concem is that the CERCLA guidance talees questkms regarding *he finality of lioones termination decleions and poseble EPA adions at sites that have complied with the NRC or equivalent Agreement State doenup standards and had their licenses terminated. On August 6,1997, I transmitted a draft Memorandum of Understanding (MOU) between our agencies that addresses these finality tasues. The purpose of the MOU,
" Consults:lon and Finality on Decommitsioning and Dectmiamination of Contaminated Sites."
j is to prowde for Sr.ality in NRC license termination decisions in order to provide liconeses and n n u n s r.,
i D/IAb nN8 Enclosure I
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i the public with a stable and predictable regulatory framework that is adequately p,%ctive of public hoshh and safety and the environment. Further, the MOU is intended to provide for earty consultation with EPA in those cases where a alts's residual aH-pathways dose exceeds 15 mram/yr.
We have spoolfloally examined the atstements in the CERCLA guidance that assert the NRC Lule is not protodive, and we And a number of them to be inaccurate, misleading, or irsoneistent with nabonal and intomational standards. The NRC staff reviewed associated EPA documents and redonale and I have included the detans of these staff findings in an endoeurs to this letter, We have not received a response either to the gene : issues raised in our August 6,1997 letter or to the specMce of the MOU. We fully intend to oroceed, and have proceeded, with impiomentsbon of the July 21,1997 finst NRC rule, both in preparation of regulatory guidance for the rule and in application of the rule for specific cases. In eddition, as you are probably aw: m, we have sought legislation the t would recognize the validity and adequacy of NRC's cleanup rule and ensure finalP.y for NRC and Agreement State licensees.
Sincerely, Original signed by Shirley Ann Jackson Shirley Ann Jackson
Enclosure:
Discussion of NRC Concems With EPA's CERCt.A Guidance Originating Ofhoe: EDO/RES SAJ - Approved Ref: CR-97-207 GJD - Travellstaff-Commission Comespondence no comments NJD - Approved EXM - ApprovedMits OFC.
SEQY OCM/SAJ NAME JS h DATE 1211/9h orrical. REcoMU COPY
- DISTRIB,UTION FOR LETTER:
LETTER TO: HONORABLE CAROL M. BROWNER FROM:
SHIRLEY ANN JACKSON DATED:
12/12/97-
SUBJECT:
CERCLA GUIDANCE C. Paperiello E. TenEyck D. Cool C. Haughney J. Greeves C. Jories C. Trottier S. Treby C. Cameron N. Costanzi M. Knapp J. Murphy M. Federline M. Weber J. Hickey R. Nelson M. Bell K. Stablein -
J. Holonich i
R. Bangart, OSP 7
D. Matthews, NRR R. Blough, R l D. Collins, R-Il C. Pederson, R-Ill R. Scarano, R-IV
/
s 7
CCC.19.1997 2331PM NO.925 P.1/1 a
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Olscussion of MRC Concems_with EPA's CERCLA Guidance With regard to specific issu'es on the protectiveness of rie NRC standard, we have reviewed the CERCLA guidance ano ind that the statement in the. CERCLA guidance that the NRC rule is not protective to be baccurate. The NRC staff reviewed associated EPA documents and rationale. The staff findmgs are described in detail below.
1.
EPA's dortvation of 1E 4 as a protective value appears to be a policy judgment, and is inceanistent with international findings.
The CERCLA guidance indicates that a risk level of 1E 4 is a level of protection that is not to be ami and that the 25 mrom/yr does criterion in NRC's final rule is not Fw6th:
because it would exceed that level. A rationale for EPNs value of 1E 4 con be found in a Endatal Bankhtr.70tica (FRN) for EPA's ' National Emission Standards for Hazardous Air Pollutants (NESHAPs)* under the Clean Air Act (S4 FR 38044 September 14,1989). The FRN notes that in the MDy! CNgga decision [ Natural Resources Defense Counell, Inc. v. -.
EPA. 824 F.2d at 1146 (D.C'. Cir.1987)], the EPA was directed to determine an acceptable risk leve! based on 1 judgment of what risks are ' ace'ptable 5 the world in which we live'.
In response to the Mrly! Chloride decision, the FRN Indicates that EPA compiled a review of societai risks to place risk estimates in perspective and to provide background and context for the EPA's judgment on acceptability of risks *in the world in which we live'. The FRN states that Individual risk of premature death in EPA's survey ranged from 1E-1 to 1E.7, and that the level of approximately 1E 4 is wPhin the range for individual risk in the survey and at a value that comports with many previous nealth risk decisions by EPA. The EPA rd value is applied ln the CERCLA context (see 55 FR at 8715 (March 8,1990)],
The Intemational Commission on Radiatk>n Pmtection (ICRP) and the National Council on Radiation Protection and Measurements (NCRP) use a different approach from EPA in setting an acceptable risk level.8 lCRP and NCRP are organizations which are chartered, and intomationally recognized, for the development of basic radiation protechen standards.
Their findings are contained in ICRP Pubhcation 80 and in NCRP No.118, respechwely.
Based on their review of health and societal issues, both documents (while nd$ing the difficulty of setting standards for en
- acceptable
- public dose limit) antve at 100 miemlyr as a level that is acceptable for exposure to radiation sources other than medical procedures.
NCRP 116 notes that this value includes a review of riska of mortality faced by the public.
The ICRP and NCRP approaches further reduce their 100 mremlyr limit by the prindple of
'optimiastion," which includes considerations of constraints (e.g.,26 mromly-) and cost-eGectiveness.
Also. EPNs use of the 1E 4 risk level is somewhat inconsistent with its own Federal Radiation Protection Guidance for Exposure of the General Public (FRG) as published for comment on December 23,1994. Specifically, the FRG is consistent with the
' As discussed in item 3. below, EPA has determined that 3E-4 is " essentially equivalent to 1E-4.
' As Attachment B to EPA's August 22,19g7 CERCLA memorandum states. EPA has rejected the NCRP approach im standards setting which EPA conectly nctes NRC uses.
fs recommendations of ICRP and NCRP, in that, FRG recommendation no. 3 endorses an annual public dose limit of 100 mrom/yr and recommendation no. 4 indicates that individual sources of radiadon exposure should have "authortzed limits" set at a fraction of the 100 mrom/yr. The FRG further states that setting such limits will often necessarily be based on broad judgments which may lead to somewhat higher values with further implementation of the AL. ARA process. While the FRG does not recomment a specific level for any one source, it does cae authonzod EPA and NRC standards for certain sources that currently exist, including 40 CFR Part 190 for the uranium fuel cycle and 10 CFR Part 61 for low-level weste disposal, both of which set authorized fractions at 25 mrom/yr.
Using the principles of setting oPindividual does and risk litnits' and *optimtzation of protection" (noted abave) and an additional margin to allow for the potential for exposure to more than one radiadon source, the NRC issued a final rule on radiological criteria for license termination. The rule includes an all-pathways dose criterion of 25 mrom/yr and further reduc 6on based on ALARA (62 FR 39058, July 21,19g7).
The EPA approach of setting an acceptable nsk levelin the context of reviewing risks acceptable in :,ociety is similar to that followed by ICRP and NCRP, but, clearly, is no more scientifically credible than the ICRP or NCRP reports. The FRN on NESHAPs acknowledges that because of the uncertainties over health effects. EPA's decision will depend to a great extent on policy judgment. Therefore, there is no reason to conclude that risk limits set through EPA's process are any more appropriate for protection than those set by ICRP and NCRP nor is there a reason to conclude that NRC's rule is not protective. EPA's simple declaration that NRC's rule, developed through extensive rulemaking in accordance with the procedures of the Administrative Procedures Act and detailed analysis and evaluation, is not adequately protective is unsupported and scientifically unsound.
2.
SPA inaccurately states that NRC's rule is not protective The CERCLA guidanco does not address several items which will further lower the estimated risk from the implcmentation of NRC's rule. These items are inherent either in the NRC rule or in the charactortsbcs of radioactive materials and include the follovnng:
a) the requirement in the NRC rule that doses be reduced below the rule's does criterion through the ALARA ("as low as reasonaldy achievable"; defined in 10 CFR Part 20) process further lowers the risk for the large majority of NRC sites; b) radioactive decay of key contaminant nucildes which, for the large number of NRC facdities with contaminant nuchdes with half Hves equal to 30 years or less, will result in reduction of the risk near or below that which EPA mig-dy declares to be protective; and c) the uncertalnues associated with estimatmg risks from radiation at such low dose levels. Although NRC indicated in the FRN for its final rule (at 62 FR 3gC62) that It was not altering its policy regarding use of the linear non-threshold model as part of the rutemaking, the FRN also stated that there are uncertainties as to whether adverse radlabon effects occur at al at the low levels of radiation being discussed.
The actual risk from 25 mromlyr is well within the boundanos of scienbfic uncertainty
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regarding the magnitude of the actual health effects at these low doses. Whether or not health effects result from a dose as small as 100 mrom/yr is uncertain, as evidenced by the following statement of the Committee on the Biological Effects of lonizing Radiation (BEIR V) in its 1990 report Studies of populations chronically exposed to low level radiation, such ;
- ose residing in regions of elevated natural background radiation, have not t i un consistent or conclusive evidence of an associated increase in risk of cc.;.cer.
This same point was made in a recent safety evaluation report for National Aeronautice and Space Administration (NASA) Cassini mission (July 31,1997), that EPA participated in, which referenced a Health Physics Society position oting that for a lifetime does "below 10 rem the risk of health effects are either too small to be observed or are non existent." Further, the Cassini report concluded that at the low individual dose rates expected that there is a high probability there w"' % no resultant later i cancers.
3.
EPA inconslatently uses its protective value of 1E 4 The CERCLA guidance states that the 25 mromtyr dose criterion in NRC's rule results in an estimated lifetime risk of cancer incidence of SE 4 and that this is not protective compared to 1E 4. On the other hand, the CERCLA guidance states that a 15 mrem /yr dose standard (estimated lifetime nsk of cancer incidence of 3E-4) h acceptable because *3E 4 is essentially equivalent to the presumptively safe level of 1E 4".
4 The CERCI.A guidance statements are inconsistent and raise two specific issues, First, it is not apparent why one value would be considered unacceptable while the other is acceptable even though both exceed the 1E-4 risk level. Second, EPA uses cancer indden'4 to assess acceptability of the radiation dose levels compared to the 1E-4 value, even though the FRN on NESHAPS (54 FR 38044) indicates that the value of 1E 4 was based on a survey which resulted in a range of lifetime risk of oremature mortality of 1E-1 to 1E 7. Thus, the point of comparison for assessing acceptability of the risk should be premature mortality. Further, it should be noted that the NCRP and ICRP usa cancer mortality as the bests for their decisions, if the risk coefficient for mortality la used, the calculated estimate of lifetime risk from 25 mrumfyr is 3.8E-4 (based on a risk coefficient of SE 4 for mortality versus 7E-4 for incidence), which appronTiates the L E 4 value that EPA concluded se essentially equivalent to the pMvs value 1E-4, 4.
EPA's une of MCLs for groundwater results in inconsistent risk levela for clanup NRC's approach of using an "all-pathwr.ys' dose criterion means that the dose to a member of the public from all pathways of exposure (alr, water, food and direct radiation) would not be permitted to exceed 25 mrom/yr for unrestricted release. The groundwater p.G.wy is included in the 25 mromtyr dose critetton and licensees are specifically Instructed to reduce the aihe-specific dose to levels below 25 mrom/yr when it is ALARA to do so. NRC has previously discussed its analyses of grourdwater and the rationale for its al69sthways standard in the FRW (62 FR 39074, July 21,1997) for its final rule, indicating there that
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4 (1) an all-pathways dose enterion provides a consistent risk-based standard, (2) maximum contaminant levels (MCL) are not set at consistent risk levels (and include some set above the NRC's dose enterion), and (3) the costs of meeting certain MCLs may be extraordinarily excessive compared to the benefits obtained in certain cases. Further, it should also be noted that NRC analysis indicates that a decommissioned site meeting the 25 mremlyr all-pathways dose crtarion is unlikely to result in a community water system delivering water to 5
the tap with concentrations above the MCLs, because of both tha process of dilution, decay, l
and tronoport in nature as the nuclides move through the aquifer and the process of water extraction, treatment, and/or distribution.
5.
EPA reference to NRC's alternato critsrls la inaccurate The CERCLA guidance characterizes the NRC rule as not protective in part because it indicates that NRC would allow a dose of up to 100 mremlyr based on an exemption process.
This ignores the statement of considerations in the FRN for NRC's cleanup rule (at e* CR 39072) which described the nature of altamate criteria and the context of use of attemate criteria within the ICRP/NCRP radiation protectinn,,amework. It should be noted that EPA's draft cleanup rule (withdrawn by EPA from further consideration by OMS in December 1996) contained provisions that also allowed for exemptions from its all-patnways and separate groundwater standards. Specifically, the EPA's cleanup rule contained provisions to allow for restricted release, the use of Institutional cLntrols with 5-year reviews, and the use of attemate concentration limits and Technical Impracticability Walvers when the amount of residual contamination exceeds the regulatory limits.
The FRN lasuing NRC's final rule stries that, 'for the very large majority of NRC licensed sites' the 25 mremlyr dose criterion would be ' appropriate end achievable," but that the Commission was concemed about certain difficult sites presenting unique decommissioning problems. The FRN for NRC's proposed cleanup rule (59 FR 43217) indicated that it was anticipated th - %nsees of these facilities might seek exemptions from the criteria of the rule. Howevt, me statement of considerations for the final rule indicate that, because these s
facilities would have to follow processes similar to those covered by the rule (e.g., evaluation of impacts and benefits, consideration of public inputs, use of Institutional controls, etc.), it was more appropriate to codify them in the regulations, rsther than have them seek an exemption from the' rule.
Liceneses of these facilities would first have to evaluate release of their site for unrestricted use under 10 CFR 20.1402 of the rule or for restricted use under 10 CFR 20.1403. Only if those requirements could not be met would the Commission consider allowing altomate criteria. De FRN notes that the Commission ev-ds that use nf altomate criteria will be
'cormned to rare situations
- and " unusual site specmc circumstances.'
In those rare esses where alternate criteria were considered, the rationale for their use dertves from the radiation jahn principles of NCRP and ICRP, namely the settmg of a limit and reduction of the dose below that limit based on a system of constraints and cost factors. NRC's cleanup rule would limit the dose for one of those unusual caaes by requiring that the dose be kept below the 100 mrsm/yr limit in 10 CFR Part 20 by a consideration of actual sources at the specific site as well as by an appl 6 cation of ALARA principles.
Specrfically, use of attemate critoria would only be allowed under 10 CFR 20.1404 following:
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(1) e detailed licenwe analysis of all man-made sources in the vicinity of the site (10 CFR 20.1404(a)(1)); (2) a public discussion of the issues involved with the use of altemate enteria for that site (10 CFR 20.1404(a)(4)); and (3) EPA Involvement in the process, and a specific approval by the Commission (10 CFR 20.1404 (b)).
Thus, the rare occurrence of use of altomate criteria, the requirements for justifying its use, and the detailed approval process required for its use, will result in allemate criteria being used only in thoes situabons where it is appropriate and where it is protecbve under the radiation protecdon principles of NCRP and ICRP.
5.
EPA le beconalstent est a,Nning whether or not redon is included in the CERCLA guidance in the Purpose section of the CERCLA guidance (page 1), EPA indicates that the polecies described include redon m a contaninant of concem. However, potential ARARs in two cases discussed do not address the dose from redon, yet are desenbod as acceptable.
In Attachment B (page 4) of the EPA CERCI.A guldance, the 10 mrom/yr standard for air emissions of radioactivity ( 40 CFR Part 61, Subpart I, now NRC's " constraint" rule) is discussed as another standard that is consistent with a maximum allowable does level of 15 mrom/yr. Since this air emission standard does not include dose from redon (see EPA CERCt.A guidance paragraph 2 on page 4 of Attachment B), it is not comparable to a dose limit cf 15 mrern/yr that includes dose from all radienuclides (that exceed back0round).
Also in Attachment B (page 5), the standards for cleanup of contaminatec'l soils around.
2 uranium mills (in 40 CFR Part 192) are described as consistent with the maximum allowable dose standard of 15 mrom/yr. However, in their reassessment of doses from contaminated soil at the limits of 40 CFR Part ig2, EPA does not include the does from the radon emissions component of the residual radium. (Note that the dose and risk assessment performed for the final Environmental Impact Statement (EIS) for the cleanup standards (EPA,1982, Final Environmental Impact Statement W Remedel Achon Standards for inacdve Uranium Processing sites (40 CFR Part 192), Rep. EPA 520l482-G13-1) indicated that the ilfotime risk from exposure to redon progeny at the standard was 2E 2.) in its reassessment, the EPA provided results for the initial ceio'alations and for two ressessaments.
The initial calculations were the same as described in a general document addressing does calculations for meny radionuclides and scenarlos, refened to by EPA as the Technical Support Document (TSD) (EPA, September 1994, Radiation Sde Cleanup Reguistions:
Technicef Sgport Document ibr the Development of Radlonuc#de Cisamp Leveis fbr So#
(Review Draft), OfRoe of Air and Radiation). In the TSO, doses for radium 226 in soll were performed both with and wtthout inclusion of the dose from the associated redon. The T3D results reported in the mesessement document are the results which do not include the dose ham raden. This is inconstatent with the stated pc4cy in the CERCLA guldence, which indicated that redon was included. Based on the salues in the TSO, the does without radon is estimated to be roughly one tenth the dose it redon is included, Indicating that (as expeceed) the dose from radon is the most important ww of the total does from radium-22e in soil.
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Allowing higrwr concentrations of radium in soil will, in tum, provide higher doses from radon.
Wthout this major component of the original analysis used to develop the standards in 40 CFR Part 192 (control of radon), higher doses to the public could result.
7.
CERCLA guidance reassesses doses from radon that results in significandy lower doses The EPA has reassessed the doses associated with concentrations of radium in soil at levels of the ciesnup standards for uranium mille (concentrabons not to exceed background by more than 5 pCl/g in the top 15 cm of soll and 15 pCL/g in any deeper 15 cm layer, in 40 CFR Part 192), and has indicated that the doses are less than 15 mremlyr (page 5 of Attachment B and page 8 of Attachment B). The doses from such contamination levels appear to be significantly underestimated. The CERCLA guidance refers to another report (EPA. July 22, 1996, Rcessessment of Radium and Thodum Scl Concentrntions and Annual Dose Rates) for details of the dose estimates. NRC also reviewed this 1996 document and raises the following issues and concems:
- a. Dose assessment should address all potential site conditions The EPA indicated in the 1996 document that the reassessment included ' generic model site characteristics, and standardized defauk exposure factors," but then indicated that EPA was "... interested in choosing modeling assumpt!ons that are
" realistic" or " reasonable," based on site-specific Information...." This assessment should be applicable to all sites required to meet the 40 CFR Part 192 cleanup standards, but it has failed to do so (see comments below on changes to area and contaminated zone thickness parameters).
- b. The satimate of the contaminated area and layer thickness are not representative in the TSD assessment, the contaminated ares was assumed to be 10,000 m' and the contaminated layer was assumed to be 2 m thick. In the 19g7 reassessment, 2
these parameters were assurned to be '...a cw,6er,ir,ated zone area of 100m and tM:kness of 15 cm, as specified under 40 CFR Part 192." The revised parameter values are not supported by the standards of 40 CFR Part 192, and do not appear to be representative of potential sites twM under the standards. Although the cleanup standards of 40 CFR Part 192 specsfy that the cleanup Imits apply to 100 m' arcos and 15 cm thicknesses of soil, there is nothing to specify or even suggest that these values should be used in does assessments. For r ^,g the dose to a potential receptor (l.s., person) at a remediated site, the actual area and depth of contamination should be used. Near uranium mill tailings siten, areas of windblown contamination een be as large as tons to hundreds of acres (tens of thousands to hundreds of thousands m*). Hence, the assumption of a contaminated area of 100 m' is untessonably small. Further, regarding the contaminated zorm thicimoes, the 40 CFR Part 192 standards clearly allow contaminated matenal thicker than 15 cm (the only thicimeos limitation is that the 5 pCL/g limit only apples to the top i5 cm of soil).
Thus, the EPA assumption that the contaminated zone is only 15 cm thick may not be reasonabia.
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l The changes to the contaminated arec and thickness appear to reduce the estimated does (not includmg the radon dose) by a factv of about 4 and therefom are very important to the results of the reassessment.
- c, Changes to shielding factor and transfer factors were not avaliable for NRC review The reassessment also includes moddicotion of the garnma exposure shiekhng factor and the soHo-pient transfer factors fmm the values used in the TSD. Information to support these changes is provided in a reference (Mauro J., SC4A, Rosasessment of the Den %d Concernredons Guidshine LevelIbr Radium in 500, memorandum dated January 16,1996, to B. Hul, EPA ORIA) which was not availatne in time for this review, Thus, these modifications have not been evaluated by the NRC staif.
8.
The CERCLA Buldence lacks a beste for the assumption that the 40 CFR Part 190 standard of 28f78/25 mrom is equivalent to 10 mromtyr The CERCLA gu. dance includes reference to a document that explains how the 40 CFR Part 190 standard of 25/75/25 is equivalent to 10 mrt Wyr and the 40 CFR Part 191 standard of 25/75 is equivalent to 15 mremlyr. The compar ais of the EPA proposed 15 rnrem effective dose equivalent (EDE) 16mit and the previous standards, described in Comparison of Critical Organ and EDE Radiation Dose Rate Limits Ibr Situations invoMng Contammated Land, i
April 1997, are technically inconsistent. The inconsistencies relate to the use of cunent dose methodologies to calculate acceptable soil concentrations under past standards. This overt':
calculational method establishes bias in the resui.ng EDE and the calculated averages to j
lower values. The comparison document itself shows that the relative consistency of the proveus standanis and 15 mrom EDE are highty radionuclide-specific and scenario-dependent. This is in part because the previous standards were based on the assumption that all organ systems are equally radiosensitive, which based on today's understanding of radiobiology is an invalid assumption. Therefore, comparisons with the previous standards cannot provide a sumcient technical basis for the 15 mrom proposed EPA standerd, because the level of risk associated with the previous standards were =: C+A., unlike the consistent level of risk used 5 the NRC standard.
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