ML20235R137
| ML20235R137 | |
| Person / Time | |
|---|---|
| Issue date: | 03/01/1989 |
| From: | Ballard R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Bunting J, Linehan J, Silberberg M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS), NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| REF-WM-1 NUDOCS 8903030167 | |
| Download: ML20235R137 (15) | |
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I MEMO TO SILBERBERG/LINEHAN MEMORANDUM FOR: J. Linehan, Director, HLPD, HLWM, NHSS J.' Bunting, Chief, HLEN, HLWM, NMSS.
M. Silberberg, Chief, WMB,.DE, RES L. Rouse, Chief, IMSB, IMNS; NMSS D. Chery, Section Leader, HTS, HLGP, HLWM P. Justus, Section Leader, GGS, HLGP, HLWM J. Wolf, 0GC FROM:. Ronald L. Ballard, Chief Geosciences and Systems Performance Branch Division of High-Level Waste Management, N?tSS l
SUBJECT:
REQUEST FOR REVIEW 0F SCOPING PACKAGE FOR PROPOSED RULEMAKING Attaciled is the Scoping Package for a Proposed Rulemaking, " Design Basis Accident (DBA) Dose Limit." The purpose of the rulemaking is to resolve uncertainties in 10 CFR Part 60 and in the rulemaking record with respect to Commission's intent regarding a DBA. The purpose of the Scoping Package is to define the rulemaking (as required by NMSS policies and procedures letter-129) prior to obtaining approval from the EDO to begin rulemaking activity.
Thus, the Scoping Package identifies regulatory uncertainties regarding the DBA in Section A and discusses elements of proof to address them in Section D.
Please review the scoping package and provide comments by C.0.B. Friday, March 17, 1989 to R. B. Heel, HLGP, HLWM, HMSS at WFN, Mail Stop 4-H.3.
(Phone: Extension 20448).
J/
Ronald L. Ballard, Chief Geosciences and Systems Performance Branch Division of High Level Waste Management, NMSS
Attachment:
As stated '
8903030167 890301 WASTE
@1 'DC DISTRIBUTION:
Central Files REBrowning, DHLWH BJYoungblood, DHLWM RLBallard, HLGP J0 Bunting, HLEN JLinehan, HLPM HLGP r/f HMSS r/f PDR & LPDR BTHomas, HLPM JKennedy, HLPH JRoberts, IMHS
'RWeller HLEN 'JPearring, HLEN RNeel, HLGP SCoplan, HLGP Blahs, RES HLPM JTrapp, HLGP RHacDougall, % O/ -
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-DFC : HLGP : HLGP HLGP L 'I : : :
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NAME :RNeel/f:] ' : Scop 1 n : RLBallard : : : p fyj,/ !
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SCOPE REQUIREMENTS FOR NEW RULEMAKING ACTIVITY DESIGN BASIS ACCIDENT DOSE GUIDANCE A. ISSUES TO BE ADDRESSED (PROBLEMS AND UNCERTAINTIES TO TO BE CORRECTED)
UNCERTAINTY 1: A regulatory uncertainty exists in 10 CFR 60 because the rulemaking record is sufficiently unclear as to whether the Commission intended the value of 0.5 rem in the definition of items "important to safety" in Part 60.2 to be used as an " accident' dose limit. According to Part 60.2:
" .. engineered structures, systems and components essential to the prevention g mitigation of'an accident, that could result in a radiation dose to the whole body, or any organ, of 0.5 rem or areater at or beyond-the nearest boundary of the' unrestricted area at any time until the completion of permanent closure" are important to safety (emphasis added).
Some have argued that the rulemaking record shows that the Commission intended to establish the value of 0.5 rem both as.a basis for identifying items l important to safety.at a geologic reposit'ory and as design basis dose limit for accidents. They cite as their bases selected statements such as the following that are taken from discussions in the final rulemaking record for i
10 CFR 60. l l
o Discussion concorning the language of definition of "important to safety" in Section 60.2:
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"such structures, systems.and components would be subject to additional design requirements and to a quality. assurance' program to ensure that they. performed their intended functions."'(48 FR 28202); j Discussion on land ownership and, control:
" structures, ; systems, and components important to safety as defined
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in'60.2 must be designed so as to limit radiation doses under accident conditions to 0.5 rem at the boundary of the unrestricted. .
area" .(48 F,R,28211, June 21, 1983);-
o Discussion concerning the design criteria in section 60.131:
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[the Commission is concerned with] " accident conditions at the HLW facility that could result in specified doses at the boundary" !
(48'FR28213).
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Also they think that the responses to public comments on the Proposed Rule suggest an implied " design basis accident dose limit." (See: Overview, Section 4.5, Important to Safety, in NUREG-.0804, Staff Analysis of Public Comments on
- Proposed Rule 10 CFR Part 60, " Disposal of High-Level Radioactive Wastes in
' Geologic Repositories _," December 1983).
SCOPE-RBN On the other hand, others have interpreted these same references to mean that the Coccission intended only to identify those structures, systems and components that "...would be subject to additional design requirements and to a quality assurance program to ensure that they performed their intended functions." They also argue that 0.5 rem was not intended by the Commission as .
an " accident dose limit" because the definition in Part 60.2 indicates that items "important to safety" are essential either for prevention of an accident or for mitigation of accidents. The final version of 10 CFR Part 60 is silent regarding an " accident dose limit." They point out that 0.5 rem is numerically equal to the dose limit permitted under 10 CFR 20 to members of the public under normal operating conditions of a nuclear facility, but not for accidents, and that both 10 CFR Part 50 and 10 CFR Part 72 contain distinctly different and explicit values for their dose limits for accident conditions.
UNCERTAINTY 2: If it is assumed that Part 60 does contain en implied requirement regarding a design basis accident dose limit, related regulatory uncertainty exists regarding the boundary for calculation of the dose. The Commission has traditionally associated the terms unrestricted and restricted areas with norral operations at a nuclear facility, not with accidents. If a design basis accident dose limit is explicitly incorporated into Part 60, this uncertainty will need to be addressed.
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. 4-UNCERTAINTY 3: The explicit relationship of the " design basis accident dose limit" to the loss of the necessary safety functions of a structure, system, or component important to safety is not included in Part 60_ resulting in a l regulatory uncertainty in 60.131(b).
UNCERTAINTY-4: Part 60 is silent on whether multiple failures and/or single failures of structures, systems, and components shculd be considered in the identification of items important to safety, the calculation of deses due to credible accidents for comparison to the design basis accident dose limit (if one is implicit in Part 60), and for the purposes of design required by Section 60.131(b).Theabsenceofsuchcriteriaconstitutesanotherregulatory uncertainty.
UNCERTAINTY 5: Further regulatory uncertainty is associated with the lower limit of probability of occurrence to be considered for credible accidents. It is ,mt clear from Part 60 what basis to use for excluding from consideratic,n those accidents of low probability of occurrence (but with high consequences) that would be used to identify systens, structures and comporents important to safety as required by Part 60.2 and to design the GROA to be in compliance with Section60.131(b).
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SCOPE-RBN UNCERTAINTY 6: Technical uncertainties are associated with the lack of definitior. of the elements to be used in the calculation of a potential dose to an individual: for comparison to any implied design basis accider,t dose limit, in the identification of structures, systems and components important to safety, and in the design of the GROA as regulated by Section 60.131(b). Some of these uncertainties include: no defined period of exposure to use for dose calculations; no definition of the type of dose (e.g., dose commitment, effective dose equivalent); no statement of the components of the dose (e.g.,
direct radiation, inhalation, ingestion, etc.).
B. THE NEED FOR THE RULEMAKING The Advanced Conceptual Design (ACD) phase, during which DOE plans to explore design alternatives and firmly fix and refine the design criteria and concepts to be further detailed in later design efforts, is presently scheduled for completion in January 1992. The absence of a clear and explicit consideration of a design basis accident dose limit creates uncertainty about how DOE should determine the adequacy of the structures, systems and components used in the ACD, and could require major redirection of future design efforts. This could affect the schedule for development of a geologic repository because of the long lead-time i equired to procure the resources necessary to design and construct the GROA.
SCOPE-RBN In order to meet the milestones mandated by the Nuclear Waste Policy Act of 1982, as amended, and milestones pertaining to DOE's production schedule in the Mission Plan Amendments, some guidance from NRC on the value for a design basis accident dose limit and how it should be used by DOE for the design of a GROA is necessary. The DOE staff has indicated that if the final rule changes are available to them by the middle of 1990, they will have sufficient time to address a design basis accu mt dose limit in their design bases.
C. ALTERNATIVES TO RULEMAKING Alternative 1: No ection on the present rule It follows from Sections A and B above that DOE would need to make a number of assumptions in order to design and construct a GROA, i.e., a number of regulatory uncertainties regarding the design of a GROA for eccident conditions would still remain. It is likely that even if these assumptions are sufficient to protect public health and safety, a potential exists for a delay in licensing due to litigation over these uncertainties. A licensing board would be confronted at the hearing stage with the same ambiguities in the rulemaking l record as were identified in Section A above.
An advantage of this alternative is that no additional NRC resources would need to be expended in a rule change action. However, no action by NRC could result in significant dollar costs to DOE due to the uncertainty in the design
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requirements for the GROA discussed in Section B and significant expenditures I l >
l of staff resources later. Any redesign at the hearing stage of the licensing action might also require that DOE extend the deadline for completion of the repository. ')
Alternative 2: Prepare a Technical Position (or Regulatory Guide) i The purpose of these actions is to provide guidance in the implementation and/or interpretation of a regulation. The current version of 10 CFR 60 contains no explicit criteria that pertain to a reference dose guideline for accidents. Further, unlike a position set forth in a rulemaking, staff positions set forth in regulatory guides, technical positions, or other documents can be challenged at a hearing. Because of the number of engineering decisions that will be based on the design basis standard, there is too much at stake to postpone a clear decision by the Commission on this issue until the licensing hearing. Therefore rulemaking would be the most appropriate context in which to reexamine the issues resulting from uncertainties 1 through 5 above even though NRC would have to expend more resources than for alternative
- 2. Uncertainty 6 could be largely addressed by a Technical Position or ,
Regulatory Guide.
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4 SC0liA BN D. H0ll THE RULEMAKING WILL ADDRESS THE UNCERTAINTIES UNCERTAINTIES 1.and 2 Although the current version of 10 CFR 60 contains performance objectives for normal operations at a geologic repository operations area (GROA), Part 60.111(a) does:not contain an analogous performance objective for accident conditions, i.e., an " accident dose limit." The proposed amendment would define a new reference guideline.(expressed as a dose) against which the design of a GROAwouldbetestedforspecified(designbasis) accidents.
To remove the regulatory uncertainties about the Commission's intention regarding an " accident doso limit," the proposed amendment contains a change to be incorporated into section 60.111(a) of 10 CFR 60 and new supporting definitions in section 60.2. The preclosure activities at a geologic repository:
operations area are expected to be sufficiently similar to those at a Monitored Retrievable Storage Facility (MRS) so that a repository can be regulated by a performance objective (i.e., a dose standard) for the design process that is similar to that for a MRS. The changes would be conceptually equivalent to whatisusedforaMRSinSections(a)and(b)ofParagraph72.106, Controlled Area of an ISFSI.or MRS, but would apply to a geologic repository.
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1 SCOPE-RBN 9-The change to Section 60,111(a) would require that any individual located on (or beyond) the neorest boundary of the surface barrier area (a newly defined
~ term), would receive a cumulative dose no greater than the more liniting of ,
1 either an effective dose equivalent (EDE) of 5 rems g a dose equivalent of 50 l rems to any individual organ or tissue (except that the maximum dose equivalent to the eye must be limited to 15 rens) during any design basis accident. The ;
need for a 50-rem dose arises in order to account for radionuclides that are deposited non-uniformly in the body (such as plutonium and the other transuranic elements that could be released in a design basis accident at a repository). This change would also resolve any regulatory uncertainty associated with the identification of a boundary where the dose due to accidents is to be calculated.
In order to emphasize the design charccter of the reference value for dose in contrast to an actual dose limit for the public in emergencies (such as might be required by Subpart I of 10 CFR 60, Emergency Planning Criteria), the proposed amendment wculd also include a footnote to modify Section 60.111(a) that will parallel the wording of the Footnote 2 to Section 100.11(a)(1) of 10 CFR 100.
A number of new definitions will need to be included in Part 60.2 to clarify the meanings of new terms that would be used in paragraph 60.111(a). Terms to r be defined include: Design bases, design basis accident, anticipated i
operational occurrences, surface barrier area, dose equivalent, committed dose
SCOPE-RBN equivalent, effective dose equivalent, and eye dose equivalent. The proposed amendment will also contain a proposed change to subsection (1) in section (c) j of paragraph 60.132 that would require surface facilities to be designed to control the release of radioactive materials in effluents for design basis accidents and also during anticipated operational occurrences, not just during' normal operations.
UNCERTAINTY 3 The regulatory uncertainty in the relationship of the " design basis accident dose limit" to the loss of safety function in Section 60,131(b) would be retained in the regulation. However, the supplementary information would clarify that it is the Connission's intent in 60,131(b) that rather than design the GROA for failure at the level of the design basis accident dose limit, the design philosophy of the licensee should be to engineer all structures, systems and components important to safety to preclude any loss of safety functions during any credible accident.
i UNCERTAINTY 4 The proposed amendment would delete the words " essential to the prevention or mitigation of an accident that could result..." from the current definition of "important to safety" in Part 60.2 of 10 CFR 60, and would substitute the following words for this phrase:
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...that fail in combination with other structures, systems, and components during credible accidents resulting..."
This wording indicates that both single failures and multiple failures are to be considered in the identification of items important to safety, the calculation of doses due to credible accidents for comparison to the design basis accident dose limit, and for the purposes of design required by Section <
60.131(b) thus removing the regulatory uncertainty. In order that the design for these " items important to safety" will be compatible with the environmental conditions associated with normal operations (such as maintenance and testing of the GROA) as well as for accident conditions, it is necessary to append language analogous to Part 72.122(b) for a MRS to the last sentence of 1 10CFRPart60.131(b)(1).
UNCERTAINTY 5 The regulatory uncertainty associated with the selection of a lower limit of probability of occurrence of credible accidents will be addressed through discussion in the supplementary information indicating that these should be identified in a manner consistent with the approach used by the NRC staff for similar facilities.
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-l UNCERTAINTY 6 Certain technical uncertainties in the calculation of dose _that are not resolved by f 10 CFR 20 and 40 CFR 191 would be removed by the addition of a new requirement l 1
to the safety analysis report, subsection (16) in paragraph 60.21(c) in 10 CFR 60. The proposed rulemaking, analogous to Part 72.24(m) for a MRS or an ISFSI, will require an analysis of the potential dose to any individual on (or beyond) the nearest boundary of a surface barrier area from accidents or natural phencrenon events that result either in direct radiation or in the release of radioactive materials to the general environment from the GROA. The proposed rulemaking would also require that the' dose calculation be performed for direct exposure, inhalation and ingestion that occurs as a result of the l postulated design basis event.
l The remaining technical uncertainties, i.e., the detailed methods for the calculation of doses resulting from credible accidents, would be published separately as a Technical Position or as a Regulatory Guide. Methods that would be acceptable to the Commission are expected to be those that are commonly accepted by practitioners of radiation protection (such as methods adopted by the NRC staff for the final rule 10 CFR 20,-December 1988; methods required by the EPA in its interagency guidance for nuclear workers (January 1987); and methods recommended in Publications 26 and 30 of the International Commission for Radiation Protection.
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SCOPE-RBP The proposed amendments are expected to make Part 60 more consistent with the current design philosophies and quality assurance practices in the nuclear industry for similar facilities.
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-E. . HOW THE PUBLIC INDUSTRY AND NRC ARE AFFECTED BY THE RULEMAKING To be prepared by RES.
F. PROPOSED NRC RESOURCES AllD SCHEDULE FOR THE RULEMAKING Both the pre-rulemaking schedule in the Final FY83 Operating Plan for the Division of HLW and the rulemaking schedule in SECY-88-285 appear reasonable at
.this time. No special technical assistance is expected to be necessary at this time.
The anticipated resources required are:
FY89 0.8 FTE FY90 0.8 FTE FY91 0.3 FTE
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It is expected that membere of the Division of HLW will interface with the following groups:
INNS - for issues related to storage of spent fuel and radioactive waste.
OGC - for legal and procedural issues.
RES - for the actual development of the rulemaking, At this time it is not thought likely that health effects calculations will be needed in support of this rulemaking. If they later turn out to be needed, RES assistance will be needed.
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