ML18025A264

Letter Responding to Letters Requesting That Certain Information Be Submitted to Address Anticipated Transients Without Scram (ATWS) for SSES Including Analysis and Justification of the GE Analysis Model ...

ML18025A264
Person / Time
Site:	Susquehanna
Issue date:	12/30/1976
From:	Curtis N Pennsylvania Power & Light Co
To:	Boyd R Office of Nuclear Reactor Regulation
References
Download: ML18025A264 (8)

Text

NRC FORM 195 I2 7II)

TO: R. S. BOYD l

ON ~os PART 50 DOCKET U.S. NUCLEAR REGULATORY OMMISSION FROM:PP&L MATERiAL's~NIM FILE NUMBER DATE OF DOCUMENT ALLENTOWN. PA. 12/30/76 N.W. CURTIS DATE RECEIVED 1 3 77 OLETTER ONOTORIZEO PROP INPUT FORM NUMBER OF COPIES RECEIVED, I

%OR I G INAL EkINC LASS IF IE D C3COP V c,O DESCRIPTION ENCLOSURE LTR. RE. THEIR 9/3P/76 LTRS...,

RESPONSE TO REFERENCED LTRS. PERTAINING TO THE ANTICIPATED TRANSIENTS WITHOUT SCRAM.....

ACKNOWLEDGZD

( 1 SIGNED CY. RECEIVED)

( 3 PAGES) 0 NOT DISTRIBUTION FOR INFORMATION CONCERNING ATWS (PRIOR TO ISSUANCE OF OL)

REMOVE PLAN1 NAME. SUSQUEHAHHA FOR ACTION/INFORMATION ASSICN D AD: VASSADM SSIGNED BC? PARR ASSIGNED LPM: MINER ASSIGNED LA: RUSHBROOK W 16 CYS ACRS INTERNAL 0 ISTRI BUTION NRC PDR ELD THADANI T 'NOV I S SM TH EXTERNAL DISTRIBUTION CONTROL NUMBER LOC PDI WILKES RE PA.

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lpga hl+ ~I Mr. Roger S. Boyd, Director Division of Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commissions Washington, D.C. 20555 SUSQUEHANNA STEAM ELECTRIC STATION DOCKET NOS. 50-387 AND 50-388 ANTICIPATED TRANSIENTS WITHOUT SCRAM ER 100450 FILE 840-2 PLA-152

Dear Mr. Boyd:

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References:

l. Letter R. Boyd (NRC) to N. Curtis (PP5L) requesting infor-mation on ATWS dated January 24, 1976.

2. Letter R. Heineman (NRC) to I'. F. Stuart (GE) .

Same subject dated April 7, 1976.

3. Letter, ED Hughes (GE) to D. F. Ross (NRC) transmitting (GE) ATWS Report, dated July 2, 1976.

4, Letter, E. Hughes (GE) to D. F. Ross (NRC) transmitting Appendices A and B to GE ATWS Report for BWR4's and 5's dated Sept. 30, 1976

5. Letter E. Hughes (GE) to D.,F. Ross (NRC) transmitting GE'ATWS Reliability Report. dated September 30, 1976.

Pennsylvania Power 5 Light Company (PP5L) received a letter (Ref:1) requesting that certain information be submitted to the NRC by December 30, 1976. This information was to address Anticipated Transients Without Scram (ATWS) for Susquehanna Steam Electric Station including analysis and justification of the General Electric analysis model and identification of design changes needed to assure that the limits specified in WASH-1270 will not be violated following an ATWS event. A related letter-to General Flectric (Ref. 2) requested infor-mation regarding the generic activity undertaken by General Electric on behalf of all BWR Category B plant owners for the purpose of developing an acceptable solution to the ATWS issue. In response to this request, General Electric has provided "for information" a generic report which included a response to out-Page 1 of 3 PENNSYLVANIA POWER IL L I GH 7 COMPANY

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standing questions. Appendices A and B to this report (Reference 4) provided information applicable to the BWR 4 and 5 which is applicable to SSES. PP5L believes, however, that the final resolution of the ATWS issue must include consideration of the GE Scram System Reliability Analysis (Ref. 5)

We have therefore prepared a dual response to the ATWS issue. The first part consists of a reliability analysis which was submitted on a generic basis by General Electric on September 30, 1976 (Ref. 5) ~ The second part provides in-formation in response to the NRC's Status Report on ATWS for General Electric Reactors.

PP6L has been involved in discussions of ATWS events with General Electric, the NRC, and industry groups, and PP5L concurs with the NRC Staff in its desire to resolve the ATWS issue as soon as practical. It must be recognized, however, that the effort to achieve resolution must not be allowed to result in an unwar-ranted impact on plant design withou't a commensurate benefit to safety.

The NRC S3atus Report states that an overall unreliability safety objective of about 10 /year, for normal and backup scram systems, must be achievable. The December 9, 1975 NRC Status Report, however, assumes that scram system un-reliability does not meet this goal, and that mitigating measures need to be incorporated for resolution of the ATWS issue. Ãe contend that the Status Report represents an extrapolation of the explicit instructions of WASH 1270 and is not consistent with the criteria documented in NEDO 20626.

PP5L believes that the ATWS issue can be resolved by analytical methods which demonstrate adequate reliability of the BWR Scram System and obviate the need for any mitigating measures. General Electric has undertaken an exhaustive reliability program to demonstrate the actual reliability of the BWR Reactor Protecton System and Control Rod Drives. GE's report on reliability was submitted to the NRC by General Electric on September 30, 1976. PP5L strongly urges an expeditious NRC staff review of this document so that the potential plant modifications can be resolved with the NRC staff and ATWS can be elimin-ated as an issue. In addition, the Electric Power Research Institute (EPRI) has conducted an extensive reevaluation of WASH 1270 methodology and data base and, as such, we believe that it should be carefully considered by the NRC staff and its reliability consultants.

In response to the NRC Status Report, a generic report, "for information purposes only", was submitted by General Electric in behalf of PP6L (References 3 and 4) defining the impact of the NRC Status Report. That document reveals that the impact of the Status Report resolution would be quite severe and does not yield a proper offsetting benefit to overall plant safety. Our order of magnitude estimate of the cost of ATWS mitigation is in excess of $ 20 million per unit, exclusive of the cost impact of the resulting delay in fuel loading. A minimum delay of one year would be caused adding about $ 70 million in escalation and interest charges. Costs of replacement power would be substantially more than this.

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The reliability studies submitted to )he NRC show that the unreliability of the BlB Scram system is less than 10 . Since this level of unreliability was established as adequate by WASH 1270, we cannot justify an expenditure of over 40 million dollars to further improve reliability.

PP5L urges that the status report solution should not be required to be imple-mented. PP5L is committed to resolution of the ATi<S concern by showing that adequate reliability can be achieved utilizing the improved Scram system as described in GE's BNR Scram Reliability Analysis. The cost of these improvements is expected to be less than $ 500,000 per unit. PP5L will implement the necessary modifications upon NRC acceptance of this solution.

Very truly yours, N. 10. Curtis WEB:JLI 112 952 Page 3 of 3

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