ML20236V592

Forwards List of Significant Technical Issues Which May Arise During Review of Evolutionary Std Advanced LWR Plants. Comments Requested

ML20236V592
Person / Time
Issue date:	12/01/1987
From:	Rubenstein L Office of Nuclear Reactor Regulation
To:	Partlow J, Roe J, Shao L Office of Nuclear Reactor Regulation
References
PROJECT-669A NUDOCS 8712040393
Download: ML20236V592 (7)

Text

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December l1,'1987 p

~ MEMORANDUM FOR: . Distribution-(see next page)

FROM: Lester S. Rubenstein. Director Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, Y and Special Projects

SUBJECT:

SIGNIFICANT TECHNICAL ISSUES'WHICH ARE LIKELY TO ARISE DURING THE REVIEW OF THE EVOLUTIONARY STANDARD ALWR PLANTS The enclosure identifies significant issues in addition to the EPRI opti7ization issues which we believe will arise during the review of the evolutionary standard ALWR plants. We would like your comments as to their accuracy and completeness.

original signed by ,

Lester S. Rubenstein, Director .{

Standardization and Non-Power J Reactor Project Directorate l Division of Reactor Projects III, IV, Y and Special Projects

Enclosure:

As stated cc: T. Murley DISTRIBUTION:

J. Sneizek .ICentral File d F. Miraglia NRC'PDR*" "

D. Crutenfield GVissing S. Varga LRubenstein T. Kenyon PDSNP Reading P. Leech D. Scaletti i 1

CONTACT:

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UNITED STATES l, 8"' ' ,n NUCLEAR REGULATORY COMMISSION

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December 1, 1987 l T j#

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( MEMORANDUM FOR: Distribution (see next page)

FROM: Lester S. Rubenstein, Director Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, Y and Special Projects

SUBJECT:

SIGNIFICANT TECHNICAL ISSUES WHICH ARE LIKELY TO ARISE DURING THE REVIEW 0F THE EVOLUTIONARY STANDARD ALWR PLANTS The enclosure identifies significant issues in addition to the EPRI optimization issues which we believe will arise during the review of the evolutionary standard ALWR plants. We would like.your comments as to their accuracy and completeness.

, [; O , M o LLMA%

Lester S.l obenstein, Director Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, V and Special Projects

Enclosure:

As stated cc: T. Murley J. Sneizek F. Miraglia D. Crutchfield S. Varga T. Kenyon P. Leech D. Scaletti CONTACT:

G. Vissing NRR/PDSNP Ext. 28208 l

DISTRIBUTION: Lawrence C..Shao, Director-Division of Engineering and System Technology Jack Roe, Director Division of Licensee Performance and Quality Evaluation James G. Partlow, Director Division of Reactor Inspection and Safeguards Charles E. Rossi, Director Division of Operational Events Assessnent Frank Congel, Director Division of Radiation Protection and Emergency Preparedness James Richardson, Assistant Director for Engineering e

Ashok C. Thadani, Assistant Director for Systems 1

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' SIGNIFICANT TECHNICAL ISSUES WHICH ARE LIKELY TO ARISE DURING THE REVIEW OF THE EVOLUTIONARY ALWR PLANTS

1. Leak-Before-Break Methodology The Broad Scope Rule Change for GDC-4 (52FR41268, October 27, 1987) is the subject of proposed new SRP Section 3.6.3, which EPRI considers to be inconsistent with the intent of the Rule change. EPRI's position is that the localized dynamic effects'of pipe ruptures should be deleted from the design basis for containment structures and the ECCS for systems in which LBB is demonstrated to apply and that only pipe whip and jets from systems for which LBB is not demonstrated should be included in design of containment structures and ECCS.

2. ~perating O Basis Earthquake and Dynamic Analysis Methods EPRI proposed an OBE of one-third the 55E in its generic site envelope instead of one-half, which is required in 10 CFR 100, Appendix A. The staff (Speis, 6/6/86) agrees that the OBE should not control the design of safety systems and intends to make an appropriate rule change at some future date, but no action to that effect appears likely soon. Revisions to

, the ASME are being considered by industry which may eliminate the OBE from controlling design. Westinghouse proposer. a 0.3 g SSE with 0.1 g OBE.

3. Source Term for Accident Analyses EPRI proposes to use improved (more realistic) source terms that are reasonably conservative. This approach is expected to result in prediction of significantly reduced offsite dose consequences. The staff is in general agreement with this objective. SRP 6.5.2 on PWR spray additives has been revised and SRP 6.5.3 has been added, civing credit to BWR suppression pools as fission product scrubbing. Revisions of RGs 1.3 and 1.4 are under way.

4. Equi > ment Seismic Qualification by Experience USI A-46 on this subject has )een resolved for operating plants but no action has been taken by )

RES for application to new plants as proposed by EPRI.

5. Tornado Design The staff declined to accept ANSI /ANS 2.3-1983 criteria as an alternative to RG 1.76 but is working on development of reduced wind speed criteria based on a staff sponsored study of tornado statistics (NUREG/CR-4461).

6. BWR Main Steamline Valves and Leakage Control BWRs are currently required to incorporate a leakage control system (LCS) to ensure the low leakage characteristics of the MSIVs in the event of a design basis LOCA. The ALWR Requirements Document (Chapter 3) includes a utility requirement to provide a non-safety-related alternative leakage processing pathway consistent with those evaluated in NUREG-1169. It will also specify that the allowable leakage is to be determined in a manner consistent with methodologies in NUREG-1169 and that the MSIV leakage for the final installed test shall be less than 50% of the allowable value. EPRI's position is currently under review, i

7. Additional optimization issues for which no details have been provided yet by EPRI include containment testiro requirements, the iodine release source term and the elimination of missile shicids for rod ejection.

The resolution of such issues may result in changes to current regulations.

8. Emeroency Diesel Generators Westinghouse currently proposes two separate emergency diesel generators, each to be sized to handle 1007 of the load requirements. There is under consideration a 3roposal to have four emergency diesel generators, each to be sized to landle 50% of the load requirements. The ACRS appears to favor four diesels. The WestinghouseFRAindicatgsuseoffour50%DGswouldmodifythefailure probability from 1.5x10' to 0.9'6 However, the Japanese have shown a preference for two DGs.

9. PRA A PRA will be be developed for each design. For operating plants and plants proposed for specific sites, it is normal aractice to consider external events which are site specific events in tie Level III o PRA. Since the designs of the ALWR projects will not have specific sites, the external events will be defined in terms of risks which are projected from design envelopes and characteristics of existing sites.

The Level III PRA is highly dependent upon on the external events (in that the external event contribution to the plant risk will normally be the dominant contributor) and will only be as good as the estimates of the external events. Will PRAs need to include external etents? Risks to public, i.e., probability of dose levels at plant sites boundaries, will be difficult to estimate without considering external events.

10. Analysis For Severe Acciderts The staff does not have an approved integral code for severe accident progression. CE Westinghouse and GE intend to use the industry developed MAAP code. The staff has already indicated concerns about the application of the MAAP code. Will the staff take on the review of the MAAP code? At least the staff will have to become knowledgeable of the code. What analyses will the staff use to verify the scenarios proposed by the applicants?

11. Physical Security Westinghouse and GE have proposed some design considerations for physical security. However, Westinghouse does not intend to perform a sabotage assersment of the design as they originally committed. CE has not yet given us much indication of their program. In addition since much of the CE System 80+ design is the current System 80 design, how much design for physical security and sabotage can we really expect? How much are we going to require. Issues such as consideration l for insider are not yet defined in the systems' designs.

12. Safety Classification of Equipment Westinghouse proposes to use ANSI j 51.2 instead of ANSI 18.2. The staff has indicated that this would be (

unacceptable and Westinghouse is currently assessing their position.

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13. Station-Blackout, Westinghouse has proposed a non-safety grade cedicated pump to provide cooling water for the the Reactor Coolant Pump Seals. The RCP seals were the major concern for station bieckout. Will the Westinghouse proposal be acceptable?

14. Fire Protection The current rule on fire protection is oriented to operating plants where minimum separation of 20 feet and plant specific exemptions are the prime means for acceptance. Vith the ALWR plants the applicants should be looking at designs for fire protection such as complete separation and the use of fire barriers. Since the System 80+

design is a revision of System 80, we are not sure yet if the design has considered this. Westinghouse has proposed use of 20 feet separation without fire barriers. The staff has indicated this design does not comply with Appendix R.

15. Core Melt vs Core Damage It appears that the licensing review bases for the stanuard designs will require a containment conditional failure probability of less than one in ten weighted over credible core damage o sequences. This will require the staff to differentiate between core damage and core melt sequences and define their probabilities. In the GESSAR II review, the staff assumed that all core damage lead to core melt and eventually to containment failure.

16. The Use of Fiber Optics and Multiplexing and Computer Control GE, W and CE intend to use fiber optics and multiplexing and computer contriils in the instrumentation and control systems. The staff does not have enuch experience in these technologies. The review will be difficult since it will be the first of a kind.

17. Implementation of Severe Accident Policy RES is developing criteria for implementation of the Severe Accident Policy and a rule, 10 CFR 52, of requirements for the Severe Accident Policy. Neither are expected to be completed in time to support the current ALWR Design Certification schedules. Meanwhile Severe Accident Issue topic papers, proposed I resolutions for USIs and GSIs, and optimization issues will be submitted by CE and GE for their designs. Westingtfouse has submitted resolutions for USIs and GSIs and have raised some of the issues discussed in the topic and optimization issues papers. Management must be willing to proceed with the reviews of the designs and to the Commission on a case-by-case basis on these issues. In additlon, without the criteria and rule developed, ACRS review of the applications will be at best ad hoc.

18. Containment Volume The proposed ABWR containment is smaller than the 6E55AR II containment which is likely to become a major issue. Also, CE has not yet proposed a containment volume yet.

19. Scope of Designs Westinghouse and GE propose to provide designs which represent approximately 75% of the total plant. CE appeers to propose only approximately 55% of the total plant. The System 80+ design consists of the NSSS, containment, enntrol room, emergency feedwater

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1 4 I system and " functional requirements" of the BOP. Is such a limited scope acceptable? It would appear that the Standardization Policy accepts ,

this; however, for an applicant that references the system, it could mean another two years of review for a license.

20. Scope of Staff Review Should the scope of review for all designs be  !

consistent. The RESAR SP/90 and the AEWR appear to have a complete review. However, CE's System 80+ is identified as a revision of the System 80 design. CE has indicated that much of the System 80+ design will not have to be reviewed. Only the revisions will need review. Has ,

the staff fully recognized this and is this acceptable?

21. Application of the Backfit Rule Since the System 80+ design is a revision of the System 80 and the FDA for Design Certification will be an amended FDA for FDA-2, CE could invoke the backfit rule on any changes which the staff would impose.

22. Application of the SRP RESAR SP/90 and ABWR will be reviewed against the current SRP. Since the current System 80 design was submitted before the

• July 1981, the date of the implementation of the SRP, the System 80+

design will not totally be reviewed against the SRP. Only the proposed changes to the System 80 design will be reviewed against the SRP. At Design Certification, is it going to be acceptable to have 80% of the design not reviewed against the SRP and 20% of the design reviewed against the SRP?

23. System 80+ - New FDA vs Revised FDA Since CE has indicated that the System 80+ design is only a revision of the System 80 design, than the FDA for design certification will be an amended FDA of FDA-2.

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