ML19209D195
| ML19209D195 | |
| Person / Time | |
|---|---|
| Issue date: | 09/13/1979 |
| From: | Thadani A Office of Nuclear Reactor Regulation |
| To: | Hanauer S Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-A-09, REF-GTECI-IS, TASK-A-09, TASK-A-9, TASK-OR NUDOCS 7910190535 | |
| Download: ML19209D195 (8) | |
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UNITED STATES l 'g,*,',,
NUCLEAR REGULATORY COMM SSIOfi E
W ASHINGTON, D. C. 20556 s
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SEP 13 IS73 TAP A-9 MEMORANDUM FOR:
S. H. Hanauer, Director Unresolved Safety Issues Program FROM:
A. Thadani, Task Manager, A-9
SUBJECT:
NRC - W - OWNERS ATWS MEETING
SUMMARY
A meeting was held in Bethesda on August 14, 1979 with Westinghouse (W) and several owners of plants designed by W to discuss plans for resolution of the Anticipated Transients Without Scram TATWS) issue and the impact of TMI-2 event on this plan.
After initial -emarks by NRC staff to divert attention back to resolving ATWS on a reasonable schedule and to address the THI-2 concerns related to ATWS, W~
and the owners made the following points (Enclosure 2).
- 1) W wants to resolve ATWS as much as the NRC.
- 2) W believes the 6/8/79 submittal answers the 2/15/79 questions. Staff has been ' rovided the vast majority of the needed information.
- 3) The proposed modifications in the balance of plant (BOP) to i. rip the tur-bine and actuate auxiliary feedwater a re straight forward, would satisfy Vol. 3 (NUREG-0460) criteria and can le implemented in a reasonable (wnths) period. However, the changes won't be implemented until the rule is effec-tive.
The staff noted that:
- 1) The 6/8/79 submittal is inadequate in that this report does not even address several questions in the 2/15/79 Mattson letter to W and the report does not provide adequate assurance that Alt. 3 fix is applicable to the operating plants.
- 2) Early Verification requirec that details of a design (fix) be provided (functional require ents being the first step) and that the design be generic to limit the impact on resources needed to design and review the fix.
1173 167 5 36 1
7910 90 1
S. H. Hanauer SEP 1d TMI-2_Related Concerns:
't the 7/25/79 meeting with the industry, the staff had sumarized the TMI-2 related concerns that needed to be addressed by the industry to assure that the proposed fixes in V0ume 3 of NUREG-0460 were still appropriate.
- 1) Blocked Valves Concern: Credit is given in the ATWS analyses for the pressure relief capability of the PORVS. However, some plants continue to operate with these valves isolated and these plants would be ex-pected to have higher peak pressures than those provided in ene generic reports.
Festingbot stated that the next ATWS report will address this issue.
home discussion ensued as to how such plant specific considerations would be addressed in the proposed ATWS rule.
- 2) Environmental Qualification Concern: The staff not,rd that systems such as the pressurizer heaters, relief and safety valves, reactor coolant pumps, makeup and purification systems could be aisabled by the accident conditions (high pressure / moisture) and therefore equipment and instrumentation qualification needed to be addressed.
W stated this item was addressable but did not commit to providing a response.*
- 3) Operation of Main Coolant Pumps: For events like a stuck open valve (on the pressurizer), early tripoing of the RCPs may be the most appropriate action. Since the ATWS analyses did not adequately consider this factor, W was asked to address this issue.
The W response was the same as in item 2 above.*
- 4) Voids in the Primary System: This concern relates to the weakness in the computer codes used to analyze ATWS and to the potential of voids prevent-ing natural circulation and/or uncovering the core (taking into account the HPSI design).
W indicated that most of these concerns were being addressed under the " Lessons Learned" effort and that ATWS concerns could be addressed after the TMI-2 re-lated activities are completed. Upon staff insistence that the TMI-2 concerns raise several questions about the appropriateness of the fixes considered under alternatives 3 and 4, W agreed to provide their planned responses follow-ing a discussion with A. Thadani* of NRC during the later part of the week.
Mr. Thadani was to provide more details of the needed infomation.
1173 168
S. H. Hanauer SEP 131979 An attendance list is provided in Enclosure 1.
- Subsequent to this meeting and following discussions between A. Thadani and R. Steitler (of W), W sent a letter to NRC (Enclosure 3) in which they outlined their plans to respond to the NRC concerns.
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Aib^A rb A. Thadani, Task Manager A-9 cc: ATWS Distribution Meeting Attendees 1173 169
ENCLOSURE 1 ATWS MEETING WITH W AND W OWNERS August 14, 1979 -
A. Thadani NRC, DSS S. H. Hanauer NRC Donald J. Statile Yankee Atomic Electric Company Steven Traisman Pacific Gas & Electric Bob Steitler W
Linda Belmonte 7estinghouse Kenneth R. Jordan Westinghouse Michael Tokar NRC Roy Woods NRC/ DOR /RSB M. Srinivasan NRC/ DSS /ICSB F. Odar NRC/ DSS /AB Morton Fleishman NRC/SD/EMSB K. I. Parczewski NRC/ DOR /RSB Kulin D. Desai NRC/ DSS /MEB James Curry NRC/RES/ PAS H. Vander Molen NRC/ DOR /RSB M. D. Stolzenberg NRC/RES/RSR Francis Akstulewicz NRC/DSE/AAB Don L. Williams TVA - Engineering Design G. E. Edison NRC/RES/ PAS 1173 170
Enconuec
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ATWS FOR WSTIfKM)llSE CURRENT STATUS WESTINGHOUSE SUEMITTED REPORT 6/899 SHO4ING THAT ALTERNATIVE 3 DEFINED IN WLLFdE 3 0F NUREG-0461 IS ACCEPTABLE.
REPORT SH0hED THE LIMITIt*3 TRANSIENTS LOSS OF OFFSITE POVER LOSS OF LOAD LOSS OF PKRMAL FEEDWATER DEPRESSURIZATION OF RCS REPORT DESCRIBED W E PRCPOSED SOP FIX THAT WOUl] TRIP THE TURBINE AND ACTUATE AUX FEED DOCUPENTED STRESS REPORTS PREVIOUSLY SENT TO NRCI EMERGENCY STRESS LIMIT FCR WESTINGHOUSE Is 32T PSI RADIOLOGICAL ASSESSPENT USING MCCEL IN NUREGM SHCHED PAXIMUM DOSE LESS MAN l@ CF 10CrT00
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BOP FIX FOR ATWS PROVIDES DIVERSE ACTUATION OF ElRBINE TRIP # O AJX FEED INPtJT COMES BOP SIDE OF PLANT hHICH IS NOT bESTINGHOUSE SCOPE PRELIMINARY FUNCTIONAL REQUIREMENTS hRITTEN #iD ARE CURRENTLY BEING REVIEbED BY OUR CUSTCFERS FIX IS STRAIGHT FORWARD NO PEETS THE INTENT OF NoC POSITION t
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fB! COTHNS FOR ADS BLOCKED PORV'S PLNiT SPECIFIC AS TO NUMBER CF VALVES AND IF THEY ARE BLOCKED SENSITIVITY STUDY IN JUNE REPORT SHOWS ONLY MCDEST INCREASE IN PRESSURE FCR CASE WITH VALVE BLCCKED ENVIRCriENTAL CUALIFICATION M/E FROM ATdS MUCH LESS THAN EITHER A DESIGN EASIS LCCA CR STEAMEREAK OPERATION CF MAIN COOLANT PLMPS CURREffT ANALYSIS ASSUPES PUMPS ARE EFFECTIVELY TRIPPED bHEN COLD LEG TEMPERATURE IS 6 F WITHIN SAERATION ISSUE OF PUFPS RUNNING CR NOT IS EEING ADDRESSED IN BULLETIN 79-C6C CPERATOR ACTICN SINCE PEAK PRESSURE OCCURS IN A 2 TO 3 MINUTE TIME FRN>E THERE IS LITTLE THE CPERATCR CM DO TO AFFECT PEAK PRESSURE CURRENT ANALYSIS SHOWS STABLE CONDITIONS REACHED IN 10 MINUTES OPERATOR HAS MANY ALTERNATIVES TO IffiRCDUCE NEGATIVE REACTIVITY SCRM ECCS EMERGENCY BCRATICN
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KEEP A WS IN FOCUS MANY 0]NCERNS WILL BE ADDRESSED BY F I RELATED ACTIVITIES SEVERE CONSEQUENCES FRGi ATWS FOR WESTINGHOUSE HAVE A VERY LOW PRCEABILITY WESTINGHOUSE WNITS THIS LICENSING ISSUE RESOLVED SHOULD BE RESOLVED IN A GENERIC MANNER SHOULD NOT BECCt'E A DESIGN BASIS EVENT ASSUMPTICfiS AND LIMITS AS DEFINED IN ALTERNATIVE 2 0F NUREG M PAY EE REASONABLE BOP FIX PROVIDES SUFFICIENT PROTECTION FROM ATWS FCR WESTINGHOUSE PLANTS RULEMAKING IN Sprits 1980
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Westinghouse Electric Corporation Power Systems PWHS A sC m ecx 355 P!n:nst1Pemrrma152:0 August 24, 1979 NS-TMA-2125 Stephen H. Hanauer Nuclear Regulatory Comission Maryland National Bank Building 7735 Old Georgetown Road Bethesda, Maryland 20014
SUBJECT:
Dear Dr. Hanauer:
Westinghouse has held and still believes that Anticipated Transients Without Scram (ATWS) is not a concern that will endanger the health and safety of the public, however, in view of the inordinate amount of Staff attention which has been given this issue it has become a licensing issue that needs to be resolved. We have submitted several topical recorts in the past that show the response of a Westinghouse NSSS to a postulated ATWS event, and in all cases have shown that the results are acceptable.
The latest report submitted via NS-TMA-2096, dated June 8,1979, demonstrated that the limiting ATWS transients result in peak system pressures below emergency stress limits and that the resulting radtalogical doses frem postulated ATWS events are a small fraction of the 10CFRICQ limtt. The report also describes possible plant modifications that will furtiter ensure that these results are valid and are offered to resolve the licensing Concerns.
The two recent meetings with you and members of your staff, on July 25 and August 14, were directed-towards redefining the AT4S issue in light of the lessons learned fecm the Three ? tile Island event. T-is redirection of the ATds issue has ex::anded the secae of ATWS. Many of the new concerns for ATWS are being addressed by other programs, in resconse to the Lessens learned Report, NUREG-0578, and the TMI-related bulletins 79-C6A and 79-C6C.
Our understanding of the staff's schedule is that a crocosed ATWS eule will be drafted in early 1980. To draft this rule the staff has informed us that additional information will be required frem Westinghouse and our cus tomers. An informal list of the cuestions and ccrcerns were received frem Mr. A. Thadani en August 17. Many of the concerns and cuestions are cualitative in nature and will recuire future clarification. The cuestions and concerns can be defined in the seven follcwing grcuos.
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NS-TMA-2125 August 24, 1979 Page Two (1)
Computer cede concerns related to the code's ability to correctly predict severe ATWS transients.
(2)
Additional transient analyses that include the original request in Dr. Mattson's letter of February 15 and many TMI-related analyses.
(3)
Additional stress calculations related to the Westinghouse June 8th submittal.
(4)
Additional dose calculations ref ated to the Westinghouse June 8th submittal.
(5)
Qualification of instruments and control ' systems during and after postulated ATWS events.
(6) long term shutdown following an ATWS event.
(7)
Plant specific input regarding the proposed hardware modificat ons and how an individual plant is covered by the generic analyses.
Responses to these questions and concerns will represent a significant amount of effort on the part of Westinghouse and our customers. Because of the manpower required to r : pond to the lessons Learned Report, NUREG-0578, and the various TMI-related k-
'a* ins, such as79-06A and 79-06C, it will not be possible to respond to all of these concerns before the end of this yea.
Westinghouse will res::end to many of the staff's conce ns and will try to meet the following schedule:
By November 15, 1979 respond to major concerns in groups 1, 2, 4 and 5; By December 30,1970 -espend to major cencerns in gmups 3, 6 and 7; and By March 30, 1980 respond to the remaining concerns.
If you have any questions please contact Mr. R. R. Steitler of my staff (412/373-4705).
Very truly ycurs, WESTINGH0fSE ELECTRIC CORPORATICN
<< bw T. M. Anderson, Manager telear Safety Cecart ect C S :...
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