ML17289A859

Part 21 Rept Re Delta CPR Transient Analysis Error for Feedwater Controller Failure Event Performed by Siemens Nuclear Power Corp.Feedwater Transient Actually Occurred on 911119.Fuel Cladding Failure Not Possible

ML17289A859
Person / Time
Site:	Columbia
Issue date:	07/08/1992
From:	Fies C, Reis M, Whitcomb D WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:
References
REF-PT21-92 NUDOCS 9209220292
Download: ML17289A859 (8)

Text

. ACCELERATED D TRIBUTION DEMON RATION SYSTEM REGULAT INFORMATION DISTRIBUTION STEM (RIDS)

ACCESSION NPR:9209220292 DOC.DATE: 92/07/08 NOTARIZED: NO DOCKET ¹ FACIL 50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION FIESiC.L. Washington Public Power Supply System, WHITCOMB,D.L. Washington Public Power Supply System REIS,M.P. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

.:.-"--SUBJECT.: -Part".21 .rept .re..delta.CPR transient analysis. error for feedwater controller failure event performed by Siemens Nuclear Power Corp.Feedwater transient actually occurred on 0 911119.Fuel cladding failure not possible.

DISTRIBUTION CODE: IE19D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: Part 21 Rept (50 DKT)

NOTES:

A, RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 0 PD5 PD 1 1 DEANiW. 1 1 INTERNAL: AEOD/DSP/ROAB 1 1 NRR DOEA/OGCB11 2 2 NRR/DRIS/RVIB9D 1 1 I 01 1 1 RES/DSIR/EIB 1 1 GN3. 1 1 RGN2 1 1 RGN3 1 1 RGN4 1 1 RGN5 1 1 SECY VANDERMEL 1 1 EXTERNAL: 1NPO RECORD CTR 1 1 NRC PDR 1 1 NSIC SILVERiE 1 1 0

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<<i 87~1992 88: 58 589 4175 PEC RAN 1-1 P. 82 10CFR21 ZVAXVATXO PER 292-706 This PER describes the content of the letter received from siemens Nuclear Power dated Zuns 17, 1992. This letter provides notification of a discrepancy in the procedure used to analyze the Feedwater Controller Failure (FRCV) event using the CORRSSM code. This safety analysis code.was used to support cycle 7 and S reload analysis and resulted in nonconservative predictions of the change in critical power ratio {h CpR) for this event.

The evaluation below was parfonaed in accordance with the requirements of PPM 1.10.3, 10CIl Reguirements and Reporting, Section 4.8.

transient analyiis define+

m~c 4~ l'rnneanan4 .Qa in ppMls 1.3.0 for the fuel ~ 3 at paragraph C.z.. The consxaeraa a answer vM~puw~iia.

since

'maintain it itanalyzes, "the capability to shut down the roactor and in a safe shutdown condiHon," as defined in paragraph 4.1.2. The safety analysis performed for the FWCP guarantees cladding integrity in response to transient conditions. It provides assurance that there is no fuel cladding failure duo to lack of cooling causod by the onset of transition boiling. The cladding is one of the first barriers necessary to provide the capability to prevent, or mitigate the consequences of accidents. The reactor fuel and its supporting analysis meet the definition of a Basic Component.

Defect is defined in PPH 1.10.3 paragraph 4.3. Paragraph 4.3.3 describes one of the conditions as <<A condition or circumstance involving a basic component that could contribute to the exceeding of a safety limit, as dofined in the WNP-2 Technical Specifications.<< Technical specification 2.1 defines the safety limits for WNP-2. Paragraph 2.1.2 defines the THERMAL POWER safety limit which reads in part, <<The MXNXNUM CRITXCM POWER RATXO {MCPR) shall not. bo 3.esI than 1.07 up to 4600 MHD/HTV cycle exposure.....<< As the 5 CPR is used to determine the MCPR the situation described h'- Si na Falls ~9+h{n +his definition of Defect.

j.80075 goal

07~1992 88 51 S89 417S PEG RtXK 1-1 P. 83 Substantial Safety Hazard (SSH) is defined in X'PM X.10.3 paragraph 4.4. A (SSH) exists if there is, >>a loss of safety function to the extent that there is a ma)or reduction in the degz'ee oC'rotection provided to public health and safety." This includea, >>exceeding a safety limit aa definal in the MNP-r.

Technical Specifications.>> The determination of a SSH for this casa is aided by the attached Pigure I.. The fuel and its

-"@pew ay aaalieaka Maa ga) $ ~gpg4 with Q~ nepal design/operating margin to allow for fuel burnup ane xlexxo~e rou patterns. However, the plant was allowed to'operate at the OLKCPR which forms the upper limit for the h CPR calculation.

Plant operation ks normally well above the OQCCPR. However, MNP-2 had operated at OXRCPR near end of cycle conditions at if power levels below approximately 80 percent and the FWCP transient had occurred the error in the analyeis would have allowed the CPR to dxop below the BMCPR. This meets the definition of a potential Dei'eat that could create a SSH as defined abov>>. This situation is highlighted by the fact that the FRCF transient actually occurred at 8NP-2 during cycle 7 on November 19, 1991. Because of the design margin, Xov fuel burnup> and the C'act that the transient occurred from 2.00 percent powex the minimum CPR was well above the SMCPR as shown in Figure 3a APPROVALS ' -Zs"-Vv C L P e>>, Campl ance Zng neer 0 L Mh corn, Nuclear Eng neer ng N P Re s, Compl anc Superv ear R L Nebr ng, Pl 77 Te 9~

ca Manager

~/8/W O' Ba)car, P ant Manager, POC C a an

CRITICAL j'DMER RAHQ (CPR)

(PER ATING 1, t8-1,78 (PR DESIGN/OPERATING MARGIN 1, 18- 1,39 OPERATING LIMIT MCPR (OLMCPR)

MARGIN FOR TRANSIENt EVENT (FMCF)

~CPR 1.86- 1.87 SAFETY LIMIT HCPR (SLMCPR)

MARGIN FOR UNCERTAINTIES 1,88 MEAN OF CPR CORRELATION

FIGURE 2 CSITICAi POWDER RATIn ZZZ DURING F4'CF EVENT NQV 19, 1991 OPERATING 1,'t2 CPR OESIGN/QP ERATING MARGIN DURING EVENT 1,35 1.23 OPERATING LIMIT MCPR (QLMCPR)

MARGIN FQR TRANSIENT W CPR - 8.16 FOR BOUNDING CREE

& CPR - 8.87 FOR FMCF 1.87 SAFETY LIMIT HCPR (SLMCPR)

MARGIN FQR UN CERT A'INTIES 1.88 MEAN OF CPR CORRELATION