ML18022A477

Submits Addl Info Re Basis for Reactor Coolant Pump Trip Setpoint Methodology to Resolve SER Confirmatory Item 33,per Verbal Request.Reactor Coolant Pumps Will Remain on for Most Steam Generator Tube Rupture Occurrences

ML18022A477
Person / Time
Site:	Harris
Issue date:	12/05/1986
From:	Zimmerman S CAROLINA POWER & LIGHT CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NLS-86-447, NUDOCS 8612150099
Download: ML18022A477 (6)

Text

REQUL RY INFORNATION DISTRIBUTI BYBTEN (R IDB)

ACCESSION NBR: 8612150099 DOC. DATE: 86/12/05 NOTARIZED: NO DOCKET FAC IL: 50-400 Shearon Harris Nuclear Po!!!er Plant> Unit 1> Carolina 05000400 AUTH. NANE AUTHOR AFFILlATION ZINNERNAN> S. R. Carolina Pou)er 5 Light Co.

RE C I P. NANE REC I P I ENT AFFILIATION DENTON> H. R. Office oF Nuclear Reactor Regulation> Director (post 851125

SUBJECT:

Submits addi info re basis for reactor coolant pump trip setpoint methodology to resolve SER Confirmatory Item 33> per verbal request. Reactor coolant pumps wi ll remain on for most steam generator tube rupture occurrences.

DISTRIBUTION CODE: B001D COPIES RECEIVED: LTR + ENCL 6 Bl ZE:

TITLE: Licensing Submittal: PBAR/FSAR Amdts 0< Related Correspondence NOTES: Application for permit rene'!al filed. 05000400 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NANE LTTR ENCL ID CODE/MANE LTTR ENCL PMR-A EB 1 PMR-A EICBB PMR-A FOB 1 PMR-A PD2 LA PMR-A PD2 PD 1 BUCKLEY> B 01 PMR-A PBB 1 ~ PMR-A RSB INTERNAL: ACRB 41 ADN/LFNB ELD/HDS1 IE FILE IE/DEPER/EPB 36 IE/DGAVT/GAB 21 NRR BMR ADTS NRR PMR-B ADTS NRR ROE,N. L NRR/DHFT/NTB ESP l~L~o 04 RGN2

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Carolina Power & Light Company SERIAL: NLS-86-007 DEC 05 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NO. 50-000/LICENSE NO. NPF-53 REACTOR COOLANT PUMP TRIP SETPOINT

Dear Mr,

Denton:

Carolina Power dc Light Company (CPRL) hereby submits additional information concerning the basis for the reactor coolant pump (RCP) trip setpoint methodology at the Shearon Harris Nuclear Power Plant (SHNPP). This information is submitted in response to a verbal request for additional information from your staff to resolve Safety Evaluation Report Confirmatory Item No. 33. The NRC reviewer requested that additional information be submitted concerning uncertainties associated with the Westinghouse Owner's Group (WOG) analysis performed to evaluate the acceptability of the alternate RCP trip criteria. This information is provided below.

The design basis Steam Generator Tube Rupture (SGTR) accident for the WOG RCP trip study was defined as a double-ended rupture of one steam generator tube on the outlet side of the generator. The location of the tube rupture on the outlet side of the steam generator results in a conservatively high initial leak rate. The SGTR accident analysis was based on realistic assumptions and expected system availability. The selection of a double-ended tube rupture as the design basis accident and the conservative break flow model in the Westinghouse LOFTRAN program provide assurance that the analysis results will be bounding for the majority of expected SGTR events. It is not necessary to

.develop a RCP trip criterion which will provide for continued pump operation for all possible SGTRs. If RCP trip should occur for a SGTR, this would not represent a safety problem since the plant safety systems are designed to handle a SGTR with a loss of, offsite power and consequently a RCP trip. The objective is to demonstrate that the RCPs will remain on for most of the expected SGTR cases so that the operator can retain normal pressurizer pressure control and will not be required to open the pressurizer PORVs.

The major assumptions utilized in the WOG SGTR analysis and the corresponding SHNPP actual values are presented below:

WOG SHNPP

l. 3-Loop Plant 3-Loop Plant

2. High Pressure Safety Injection High Pressure Safety Injection

3. SG Tube ID = .660 in SG Tube ID = .660 in No Load Tav = 557 F No Load Ta~ = 557'F

5. RCS Flow = $92,800 RCS Flow = $92,800

6. AFW Flow = 1520 gpm AFW Flow = 1520 gpm

7. SI Flow (Beaver Valley Flow Curve) SI Flow (SHNPP Sl Flow Higher) ooI 411 Fayettevilte Stree + P. O. Box 1551 o Raleigh. N. C. 27602 8612150099 861205 i ]

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-Office of Nuclear lctor Regulation NLS-86-007 / page 2 As shown above, the major assumptions used in the WOG SGTR analysis were actually SHNPP specific values with the exception of safety injection (Sl) flow. The Beaver Valley Plant SI flow was chosen for conservatism since lower Sl flows produce lower final pressure results.

The results of the WOG SGTR analysis indicate that for SHNPP, the minimum RCS pressure for SGTR will be equal to 1503 psia Based on the similarity of the major assumptions used in the WOG analysis to the actual SHNPP values and the use of the LOFTRAN program for modeling break flow, which produces conservatively high break flow rates, the WOG SGTR analysis results in conservative RCS conditions which accurately model SHNPP. The SHNPP minimum RCS pressure for SGTR of 1503 psia is sufficiently separated from the SHNPP RCP trip criteria setpoint of 1360 psig to assure that unnecessary trips of the RCPs will be minimized.

If you have any questions on this subject or require additional information, please contact me.

Yours very truly S. R. Zimm rman Manager Nuclear Licensing Section JHE/bmc (5081 JDK) cc: Mr. B. C. Buckley (NRC)

Mr. G. F. Maxwell (NRC-SHNPP)

Dr. 3. Nelson Grace (NRC-RII)

Mr. W. C. Lyon (NRC-PARS)

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