ML18018B916

Forwards Justification for Value Less than 14.7 Psia for Min Containment Pressure Based on Conservatisms in ECCS Analysis as Discussed on Page 6-9 of SER (NUREG-1038)

ML18018B916
Person / Time
Site:	Harris
Issue date:	05/13/1985
From:	Zimmerman S CAROLINA POWER & LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
RTR-NUREG-1038 NLS-85-115, NUDOCS 8505160157
Download: ML18018B916 (7)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESS/ON NSR:05051001~ OOC,CATE: 85/05/13 NAIZEO: NO DOCKET F'ACIL 50 400 Shearon Harris Nuclear Power Plantg Unit 1< Carolina 05000400

'AUTHNNAME AUTHOR AFFILIATION ZIMMERMANES.R. Carolina Power 8, Light Co.

RECIP ~ NAME1 RECIPIENT AFFILIATION DENTONgH,RE Office of Nuclear Reactor Regulationi Director SUBJECT Forwat ds Justification for value less than 14.7 psia for min containment pressure based on,conservatisms in ECCS analysis as discussed on Page 6 9 of SER (NUREG 1038),

DISTRIBUTION CODE.: B001D COPIES RECEIVED:LTR ENCL SIZEi TITLE: Licensing Submittale PSAR/FSAR Amdts 8 Related Correspondence" NOTES; RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL IO -CODE/NAME'RR LTTR ENCL NRR/DL/ADL 1 0 LB3 BC 1 0 NRR LB3 LA 0 BUCKLEY5B'1 1 1 INTERNAL'CRS 01 6 6 ADM/LFMB 1 0, ELO/HDS1 0 IE FILE 1 1 IE/DEPER/EPB 36 1 1 IE/DQA VT/QAB21 1 1 NRR ROEgM,L 1 1 NRR/OE/AEAB 1 0, NRR/DE/CEB 11 1 1 NRR/DE/EHEB 1 NRR/DE/EQB 13 2 2 NRR/OE/GB 28 2 2 NRR/DE/MEB 18 1 1 NRR/DE/MTEB 17 1 1 NRRIOE/SAB 1 1 NRR/DE/SGEB . 25 1 1 NRR/DHFS/HFEBOO 1 1 NRR/DHFS/LQB 32 1 1 NRR/OHFS/PSRB 1 1 NRR/OL/SSPB 1 0 NRR/DS I/AEB 26 1 1 NRR/DSI/ASB 1 1 NRR/DSI/CPB 10 1 1 NRR/OSI/CSB 09 1 1 NRR/OS I/I CSB 16 1 1 NRR/OSI/METB 12 1 1 NRR/DS I /PSB 19 1 1 NR RAB 22" 1 1 NRR/DS I/RSB 23 1 e. ILE 00 1 1 RGN2 3 R IMIB 1 0:

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CÃQE Carolina Power 8 Light Company SERIAL: NLS-'85-115 NY: 1 3,1S85 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT UNIT NO. 1 - DOCKET NO.50-000 MINIMUMCONTAINMENT PRESSURE

REFERENCE:

April 23, 1985 letter from A. B. Cutter (CPdcL) to H. R. Denton (NRC).

Dear Mr. Denton:

Carolina Power k Light Company hereby submits information (Attachment 1) justifying a value less than 10.7 psia for minimum containment pressure as discussed on page 6-9 of the Shearon Harris Nuclear Power Plant (SHNPP) Safety Evaluation Report (NUREG-1038). Attachment 1 justifies a value of 13.7 psia for minimum containment pressure based on conservatisms in the ECCS analysis. Technical Specification changes as a result of this justification were included in the revised "pen and ink" version of the SHNPP Technical Specifications transmitted via the referenced letter.

Please review the 'attached information and revise the Safety Evaluation Report, as necessary. If you have any questions, please contact Mr. Gregg A. Sinders at (919) 836-8168.

Yours very truly, S. R. merman

,Manager Nuclear Licensing Section GAS/ccc (1351GAS)

Attachment Cct Mr. B. C. Buckley (NRC) Mr. Wells Eddleman Mr. 3. Huang (NRC-CSB) Mr. John D. Runkle Mr. G. F. Maxwell (NRC-SHNPP) Dr. Richard D. Wilson Dr. 3. Nelson Grace (NRC-RII) Mr. G. O. Bright (ASLB)

Mr. Travis Payne (KUDZU) Dr. 3. H. Carpenter (ASLB)

Mr. Daniel F. Read (CHANGE/ELP) Mr. 3. L. Kelley (ASLB)

Wake County Public Library 85051trt0157 8505i3 PDR ADOCK 05000400 E PDR 411 Fayettevilte Street o P. O. Box 1551 o Raleigh, N. C. 27602

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ATTACHMENT 1 SER (NUREG-1038)

"The staff has reviewed the applicant's input parameters used in the minimum containment pressure analysis including initial containment conditions, containment net free volume, passive heat sinks, heat transfer to passive heat sinks, containment active heat removal, and containment purge system operation, and found them all to be acceptably conservative and in conformance with BTP CSB 6-1, with two exceptions.

The first exception is that the assumed initial containment pressure used in the analysis (10.7 psia) has not been demonstrated to be conservative. The initial pressure assumption is acceptable, however, if the'plant Technical Specifications restrict the normal operating containment pressure to be greater than the value of 10.7 psia that was used in the analysis."

RESPONSE

The SHNPP ECCS analysis used an initial containment pressure of 10.7 psia. However, under certain circumstances during full power operation, the containment pressure may fall below 10.7 psia. This information justifies applicability of the analysis for operation of SHNPP at containment pressures less than 10.7 psia.

It has long been established that the operational containment gas pressure condition, not the Technical Specification extreme pressure value, is appropriate input information in an Appendix K analysis. Such guidance was originally given in 1970 in Appendix A of "Status Report by the Directorate of Licensing in the Matter of Westinghouse Electric Company ECCS Evaluation Model Conformance to 10 CFR 50, Appendix K."

Furthermore, Branch Technical Position CSB 6-1 in NUREG-0800 states that "minimum containment pressure... encountered under limiting normal operating conditions should be used."

The Westinghouse ECCS containment pressure model contains a number of built-in conservatisms to offset any uncertainty about the initial containment pressure value of 10.7 psia. For instance, containment wall condensing heat transfer coefficients during blowdown equal five times the value specified by the Tagami correlation. The Tagami correlation was established from tests as a method to define accurately containment wall heat transfer coefficients following a LOCA event. The impact of using the highly conservative five times Tagami coefficients exceeds the effect of any possible uncertainty in initial containment pressure. From existing sensitivity studies the following comparison can be made regarding calculated containment pressure at 200 seconds:

Impact of reducing initial pressure by 1.0 psi = -1.2 psi Impact of using Tagami instead of 5 times Tagami = 3.8 psi Margin in calculated pressure = 2.6 psi Another large conservatism in the ECCS evaluation model is the consideration that spilling streams of accumulator and pumped safety injection water reach thermal equilibrium with the containment atmosphere. In fact, these water streams would heat up only slightly during their fall to the containment floor. In the SHNPP ECCS (1351GAS/ccc )

containment pressure analysis, the spilling water removes an=amount of energy from the atmosphere equivalent to 2 psi worth of containment pressure at 200 seconds. Again, this 2 psi of conservatism in the ECCS containment model acts to balance the potential 1.2 psi reduction in pressure which occurs in the extremely unlikely event that full power power operation occurs at 13.7 psia containment pressure. Other examples also exist which illustrate that conservatism present in the ECCS evaluation model is more than adequate to accommodate the assumption of an unusual initial containment pressure conditions. The basis of the ECCS containment pressure analysis submitted is appropriate for SHNPP and is consistent with the established LOCA evaluation model philosophy.

(1351GAS/ccc)

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