ML19220B690
| ML19220B690 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/25/1975 |
| From: | Washburn B Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7904270220 | |
| Download: ML19220B690 (6) | |
Text
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s arch 25, 1975 A' CKET ;it
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AFPLICXiTS :
Metropolitan Edison Cenpany (Met-Ed)
Jersey Cantral Pcwer & Lis;ht Co: pany Pennsylvania Electric Co=pany FACILITY:
Three Mile Island Nuclear Station, Unit 2 ( M -2)
' SCDO.2T OF MIZTING HEI.D ON FESRUARY 27, 1975, TO disci'SS ATJS IN TMI '
On February 27, 1975, representatives of Met-Ed and Babcock & Wilcox (35W)
Set witn tne Nuclear Reattor Regulation staff at Bethesda to discuss the applican ts ' assessment of anticipated transients without s cra:': (AT45), the staff's specific concerns relative to AT4S in Tf!-2, and the applicants' response to the licensing positions of WASE-1270, Anticipated Transients Without Scram for Water-Cooled Power Reactors.
A list of attendees is attached.
SACKGROCiD TMI-2, a 35W 177 fuel assembly reactor, is designated as a Categori 3 plant in tiASII-1270, Appendix 3.
The need for provisicas for ATJS in M-2 was noted in the AEC construction pernit stage Advisory Cc=mittee on Reactor Safeguards Report, July 17, 1969. The s taff's licensing position on ATJS, effective October 1,1973, is stated in WAS!!-1270. A 3&W topical report, BXJ-10099, filed en December 13, 1974, for generic review by the staff, has been referenced by the applicants. The appli-cants' letter, dated February 14, 1975, stated that they had completed their review of 2N.i-10099 and have concluded that neither odifications to the TMI-2 plant nor FSAR changes vill be required to conform to the requirements of '4 ASH-1270.
DISCUSSION The applicants ' representatives stated that their letter of Februarv 14, 1975, endorses 3AW-10099 and that the applicants vant to take credit for ICS (Integrated Control System) action during an ATiS event. '"i repre-sentatives presented a su==ary of their generic AriS -analyses and conclusions.
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-2 L e staff atsted tnat JASH-12 70 is sucject to scre inter-retation and tha:
their positions at this time are based on their interpre tations of t; tis docu=ent and on tneir evaluation of tne analyses which have been submitted.
F.ngineering justification is needed to support other possible in te ro re ta-tions of WASE-1270. _ _The s taf f s tated that we allow no credit for IG rod run-back f eature in ~1I-2 at this time.
The probabilitics of postulated transients are included in BAW-13016 whic$
is referenced in 3AW-10099.
C&W continues to believe that probabilities of the postulated transients and probabilities of failure to scram are suf ficiently low to result in an acceptably low probability o f the AT'O event.
(S&W has stated that the probability of failure to scran on de=and is 10- 5. ) The staff noted that this position does not confor= to WASH-127' The staff stated that one requirenent of WASB-1270 is that the arolicanti address coc=en mode failures in IMI-2.
Topical reports. 3AW-ifG 9 which addresses co=on mode failure in the ICS, 3AW-10016 which addresses cormon sede f ail tre in the RPS (Reactor Protection System) and 3AW-lG019, were referenced by the applicants' representatives as addressing this requirement.
B&W analyses show that tho emergency s tress limits assumed by 3&W are exceeded for two postulated transients (loss of feedvater and loss of offsite power) in 177 fuel asse=bly plants unless rod drop or rod run-back occurs. However, the staff explained that the no rod drop (scram) condi-tion is i= posed by WASE-1270. The staff has taken the position that, unless adequate diversity and reliability in the shutdown system is demon-U stratod, no inward notion of the rods is to be assumed in the ATVS analyses.
In. the absence of such a deconstration for the centrol rod drive mechanists (CRDM) in this Category a plant, the staf f, as stated in previous =eeting:
' with BaW, will allow no credit for rods being inserted by means of ICS action. The staff asked B&W to discuss this diversity and reliabilit/. E5W st_ated that the staif had previously asked them to discuss the diversity of the ICS and that they were prepared to discuss CREM diversity at a later meeting with the staff. The staf f presently has insuf ficient information to conclude that all 69 control red drives (CRD) could not fail due to so=e common cause. 3&W was asked to identify and discuss all potential corron mode failures in the CRDM. Diversity and reilability throughout the syster L,must be demonstrated. The staff stated that co=on mode failures are conceivable in mechanical syste=s as well as in electrical systecs, e.g.,
C2D vs. elMical cir51t$. ~EG itated~that rod run-back 'and r f scra:
~ fe71Ee5 functions Ad' 'that theylU ~ provide d'eir ' bas 5 Aorihis ~ ~
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a p'osition to' the s taf f.
B&W also stated that, if the failure occurred in the rod drives, the signal to scram produced by the transient would interru::
power to the rods and prevent them from being driven.
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_ 3-The staff stated that s tatis tics based on execrtance to date cannot cc -
pletely prove the 1 probability of CRD failure.
ne staff stated that it
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does not have sufficient infor=ation to conclude that the probability of failure of the shutdown system is less than 10
- usins; the cethodolocy presented in WASH-1270. The staf f also stated that using the sa:e method, the probabilley for failure of the control rod drives only cannot te accepted as less than 10'.
Improved reliability could only be statis-tically demonstrated if single rod scrams are assu=ed to be adequate tests of common =oda failure. The validity of this assumption has not been de=ons trated.
B&W stated that ESFAS (Engineered Safety Features Actuation Sys tem) actice resulting from high contain=ent pressure is diverse from the RPS action.
The s taf f stated, however, that the analysis for the pressurizer safety valve stuck-open transient is incorrect because the discharge frca the safety valves was assu=ed to go to the containment rather than to the quench tank.
Lis assumption resulted in earlier operation of the safety injection systeme. The staff, therefore, asked B&' to provide a realistic analysis for the safety valve stuck-open transient.
The B&W representatives indicated that they are prepared
- .o discuss diversity and co==on mode failures with the staff at a later =ceting, the ti=e of which would be established after this =eeting.
The staff asked B&W to submit a report on CRD diversity and reliability.
B&W indicated that they will submit this report within two weeks.
3&W takes the position that exceeding their assuced emers; enc, stress limit (l'.'e., a system pressure of 3750 psig) is acceptable. Ihis is based u:on an acceptable risk derived from consideration of the probabilities of ATJS, the relatively small number (5) of 177 fuel assembly plants, the divarsity
, of the ICS and the rod-drop feature. The staff noted that this is not in
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conformance with their interpretation of WASH-1270.
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- Ihe staff asked what corrective measures B&W could Gndertake to declude or minimize the transient overprassure. B&W indicated that they had not perforced such a study and were not prepared, at this time, to discuss this in depth. However, refined models or additional safety valves might
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be possibilities. B&W stated that to date they-had principally examined key parameters affecting the transient overpressure.
The staff stated that the B&W ATWS analysis should address the concern of safety valves not re-closing. It is not a requirement that these valves
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- reseat if consequences are acceptable. ~~Mcwever, an analysis is necessary since ve d5~~n~ot kncsi,'ipriori, how these vaives vill 3rform. ~In particu-
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lar, they would likely be subjected to abnormal forces during an ATJS blev-down. The analysis should consider a range offvalve performance values.
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The staff stated that the applicants' le t t e r o f Feb rua:, 1!., 1975 and presentation at this mee ting indicate that the applicants have not addressed all the concerns of WASH-1270. The staff stated the following to the appli-cants:
1.
The applicants are responsible for resolving AT45 in their application for the TY.1-2 operating license.
2.
There t.re requests for information requiring response by 5&W which are or may be significaat in ter=s of plant impact. We desire to keep the applicants informed ar.d we will send copies of our tequests to the app 11can es as ~ ve11.
3.
The possibility of =1ssiles resulting from AT4S events should be considered. In particular, we need assurance that designs are adequate for the stuck-open pressurizer safety valve event.
_ 4., The T:fI-2 design should be analyzed for the effects of the blevdown flove associated with ATWS eve.nts, e.g., for the stuck-open pre sourizer safety valve, relief tank ruptura must ba conside r ed.
5.
We need assurance that the line and courponents downstream of the pressurizer safety valve vill not limit the fluid flow.
6.
Additional safety valves may not preclude system overpressure if the additional flow cannot be acceemodated.
7.
Blevdown reaction forces on pipes and valves should be analyzed.
The applicant should be able to start this analysis at this time.
8.
Centainment subcompartment pressures need to be analyzed. The appli-canta should do a scoping-type analysis now: this type of analysis can acceptably demonstrate adequacy of the subeccpart=ent design.
9.
It is appropriata and possible to start addressing these plant i
-.spe_cific itana at this time.. - - - - -
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The applicants'. representatives stated that they recognize and under-stand the concerns expressed by the ~ataff and that they have not addressed those concerns at this time.
Ibe staf f asked if all valves in the auxiliary feedvater lines would be fully cpen.
The response was affirmatory mpr. for tha flow control valve dich is operated by the ICS.
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. Sere was also a brief discussion of a draf t of the staff's request for information covering EL-10099 and 3AU-lC098-F.
B&W asked for additional discussion of Request 112.1 to expand the energency condition stress limits analysis to the 145FA and 205FA plants. Pequested discussion was held following this meeting.
B&W asked for additional discussion of the =cderator coef ficient to be used in the analyses requestsdnin 210.1 and they stated that they believe that the analysis requested in 210.1 using no relief valve action departs free previous unders tandings. The staff did not agree that Request 210.1 wculd be a departure. Requested discussion was held folicwing this meeting.
In Itaquests 210.2 and 310.7, B&W questions bringing tne plant to cold shut-down condition in the analysis.
"ae s taf f discussed this ques tien with 35~.0 following this meeting.
The staff target date for issuance of the 35W Category 3 plant A7.iS SER was s tated to be May 30, 1975. To achieve that date, B&W responses to our requests vill be required by March 15, 1975.
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B. Washburn, Proj ect Manager Light Water Reactors 3 ranch 2-2 Division of Peactor Licensing Enclosuie:
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9 MEETING
SUMMARY
DIS *RI3UTICN Docket No. 50-320 Metropolitan Edison Cc=pany Metropolitan Edison Co=pany George F. Trowbridge, Esquire ATTN:
Mr. R. C. Arnold Shaw, Pite=an, Potts & Trowbridge Vice President 910 17th S treet, N. W.
P. O. Box 542 Washington, D. C.
20006 Reading, Pennsylvania 19603 Mr. Thc=as M. Cri== ins, Jr.
Mr. Richard W. Heward Safety and Licensing Manager Project Manager GPU Service Corporation GPU Service Corporation 260 Cherry Hill Road 260 Cherry Hill Road Parsippany, New Jersey 07054 Parsippany, New Jersey 07054 Chauncey R. Kepford, Esquire Chairman York Co==ittee for a Safe Environ =ent General Delivery York, Pennsylvania 17401 Docket File O. Parr A. Schwencer NRC PDR
=
Local PDR R. Schemel NRR Reading D. Zie: ann LWR 2-2 Reading P. Collins R. Maccary G. Knighton V. Stello G. Dicker R. L. Tedesco B. Youngblood H. Denton W. Regan J. Knight S. Varga S. Paw 11cki M. Williams L. Shao R. Klecker T. Novak F. Schroeder EP Project Manager D. Ross R. Houston Project Manager T. Ippolito ELD C. Long IE (3)
G. Lainas M. Service V. Benarey.
ACRS (14)
B. Gri=e:
D. Muller W. Ca==ill W. Butler J. Kastner
.J.
Stolz M. Spangler R. Clark R. Ballard T. Speis V. Moore D. Vassallo R. DeYoung K. Fniel D. Skovholt 81-182
e Attachment ATTENDEES TMI-2 ATWS MEETING FE3RUARY 27, 1975 NAME AFFIEIATION
- 3. Hernady Met-Ed D. Grace Met-Ed T. Crimmins GPUSC J. Vann GPUSC Z. G. Wallace GPUSC R. J. Chisholm GPUSC A.
F. Zallnick B&R J. F. Mallay 3&W W.
R. Gray 3&W R. J. 3rockman 3&W L. Fletke B&W C. Russell 3&W R. E. Schaffstall 3&W R. Muller NRC:ACRS Staff
- S.
Varga NRC DRL R. W.
Klecker NRC:L
- T. Novak NRC:TR A.
Schwence" NRC:L W. Minners NRC:TR A. Thadani NRC:TR L. N. Olshan NRC:TR
- E. Marinos NRC:TR R. F. Audette NRC:TR J. Giannelli NRC:L F. Cherny NRC:L D. F. Eunch NRC:L
- 3. W. Washburn NRC:L
+ = Part time attendance 81-183