05000461/LER-1997-001, :on 970103,nuclear Fuel Supplier Failed to Analyze Turbine Pressure Regulator Downscale Failure Event in off-rated Condition Per 10CFR21.21.Caused by Error in Nuclear Fuel Supplier.Mcpr Will Be Implemented
| ML20134C592 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 01/28/1997 |
| From: | Chickering R, Connell W ILLINOIS POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-97 LER-97-001, LER-97-1, U-602685, WC-075-97, WC-75-97, NUDOCS 9702030199 | |
| Download: ML20134C592 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 21.21(c)(4) 10 CFR 21.21(c)(3) |
| 4611997001R00 - NRC Website | |
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2 illanois Power Company Clinton Power Station P.o. Box b78 Clinton,!L 61727 Tel 217 935-5623 4
Fax 217 935-4632 j
WC-075-97 wiirred conneti January 28,1997 Vi e President j
ILLIN9BS ue2as i
P4pWER 2c.22o i
4 Docket No. 50-461 10CFR50.73 I
10CFR21.21 Document Control Desk l
4 Nuclear Regulatory Commission Washington, D.C. 20555 4
i
Subject:
Clinton Power Station - Unit 1
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Licensee Event Report No. 97 001-00 and 10CFR. Part 21 Reoort No. 21-97-003 i
Dear Madam or Sir:
I Enclosed is Licensee Event Report (LER) No. 97-001-00 and 10CFR, Part 21 Report No. 21-97-003: Failure ofNuclear Fuel Sunolier to Analyze Turbine Pressure Renulator Downscale Failure Event in the Off-Rated Condition Results in Operation in an
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i Unanalyzed Condition This report is being submitted in accordance with the
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requirements of10CFR50.73 and 10CFR21.21.
1 Sincerely yours, l
1 i
Wilfred Connell Vice President RSF/krk i
i Enclosure i
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cc:
NRC Clinton Licensing Project Manager NRC Resident Office, V-690
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Regional Administrator, Region III, USNRC i
O3q Illinois Departmer.t ofNuclear Safety g
9 INPO Records Center GE Nuclear Energy 9702030199 970128' PDR ADOCK 05000461 g
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d PeRC FORM 366 U.S. NUCLEAR RE1ULATORY COMMISSION APPROVED LY OMS NO. 31604 W I4 951,
ExPows 04/so/es ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THiS MANDATORY INFORMATION COLLECTION REQUEST 60 0 HRS.
REPORTED LESSONS LICENSEE EVENT REPORT (LER)
LEARNED ARE INCORPORAM INTO THE LICENSING PROCESS AND FED SACK TO INDUSTRY. FORWARD COMMENTS REGARD 8NG BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MAN AGEMEN T BRANCH (T -6 F331 U.S NUCLEAR REOULATORY COMMISSION. WASHfhGTON. DC 20666 0001, AND (See reverse for required number of TO THE PAPERWORK REDUCTION PROJECT (3160 0104), OFFICE OF digits / characters for each blocH MANAGEMENT AND SUDGET. WASHINGTON. DC 20603.
F ActuY Y NAMt (tl DOCKET NUMBWI(2)
PAOg (3)
Clinton Power Station 05000461 1 OF 5 TITLE Mi Failure of Nuclear Fuel Supplier to Analyze Turbine Pressure Regulator Downscale Failure Event in the Ofr-Rated Condition Results in Operction in an Unanalyzed Condition i
1 EVENT DATF 151 LER Nasaamcal ggi app 0 tT DATl! 171 OTHER FACILITIES INV SLVED (81 i
MONTH DAY YEAR YF.AR stoutNTiAL Revision MONTH DAY YEAR FACluTY NAME DOCKET NUMBER NUMBER NUMBER None 05000 01 03 97 97 001 00 01 28 97
'^c'un N AME DOCKET NUMacR None 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT To THE REQUIREMENTS OF 10 CFR 4: (Check One or more) l11)
MODE (9) 5 20.2201(b) 20.2203(a)(2)(v) 50.73(a)(2Hi) 50.73(a)(2)(v'ii)
POWER 20.2203(a)(1) 20.2203(aH3)(i)
X 50.73(aH2Hii) 50.73(aH2)(1) i LEVEL (10) 1 000 20.2203(a)(2Hi) 20.2203(aH3)(ii) 50.73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv)
X OTHER 20.2203(a)(2)(iii) 50.36(C)(1) 50.73(a)(2Hv)
Specif y in Abstract below or M NRC fann 366A j
20.2203(aH2)(iv) 50.36(C)(2) 50.73(a)(2Hvii)
UCENEFF CONTACT FOR THIS LES (171 NAME TELEPHONE NUMBER (include Area Codel R. W. Chickering, Engineering Projects (217) 935-8881, Extension 3334 i
1 1
COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE
SYSTEM COMPONENT M ANUF ACT URER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUF AC T UQ R REPORTABLE TO NPROS TO NPROS 1
SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR i
SUBMISSION DATE (15)
YES X
NO (if yes, complete EXPECTED SUBMISSION DATEL ABSTRACT (Limit to 1400 Spaces, i.e., approximately 15 single-spaced typewritten lines) (16) l Because of a nuclear fuel supplier error, the Turbine Pressure Regulator Downscale Failure (PRDF) event for 40 to 80 percent of rated thermal power had not been quantitatively analyzed during past operation. The fuel supplier issued a revision to the power-dependent operating limit for the cycle 7 Minimum Critical Power Ratio (MCPR) to correct the previous limit which was not l
adequate for conditions between 40 and 80 percent of rated thermal power for the PRDF event. Utility engineers reviewing the documentation identified that there was some potential to exceed the Safety Limit MCPR if the PRDF event had occurred during any of the past 5 fuel cycles.
The engineers identified that the plant had operated in an unanalyzed condition during fuel cycle 6 and may have operated in unanalyzed conditions during fuel cycles 2, 3, 4,
and 5.
The cause of this event is attributed to an error by the nuclear fuel supplier in determining which events were the limiting anticipated operational occurrences that required analysis for the fuel design.
Corrective action includes implementing corrected power-dependent operating limits for the MCPR.
This event is also reportable under 10CFR, Part 21.
NHCfOHM 366 44-95) i
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NRC FORM 388A U.S. NUCLEAR REIULATORY COMMIS4lON (444)
LICEN8EE EVENT REPORT (LER)
TEXT CONTINUATION FAr* ffY "" fil DfmKET tsner - 0n PAGFfM YEAR SEoOENTML REWSON NUMBER Nuunrn Clinton Power Station 05000461 97 001 00 2
OF 5
I TEXT (W more space is required, use additiorset copies of NRC Form 366A) (17)
DESCRIPTION OF EVENT
1 On January 3, 1997, the plant was in Mode 5 (REFUELING) and the nixth refueling outage (RF-
- 6) was in progress. Reactor [RCT) coolant temperature was being maintained between 75 and 85 degrees Fahrenheit and pressure was atmospheric.
B cause of a nuclear fuel supplier error, the Turbine Pressure Regulator Downscale Failure (PRDF) event for 40 to 80 percent of rated thermal power had not been quantitatively enslyzed during past operation for fuel cycles 2, 3, 4, 5, and 6.
The PRDF event leads to a larger change in the power-dependent operating limit Minimum Critical Power Ratio (MCPR) than any of the other Anticipated Operational Occurrences. This condition is unique to the
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Boiling Water Reactor (BWR)-6 reactor type because a single failure may cause the pressure rcgulation system to fail downscale, j
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Th3 fuel supplier issued a revision to the power-dependent operating limit for the MCPR for fusi cycle 7 to correct the previous limit which was not adequate for conditions between 40 3
cnd 80 percer.t of rated thermal p*wer in the PRDF event. Utility engineers were performing en approval review of the fuel supplier documentation for the fuel cycle 7 Supplemental R31oad Licensing Report and the core performance monitoring computer [ CPU) [IO) data bank.
1 Th3 review identified that there was some potential to exceed the Technical Specification Safety Limit MCPR if the PRDF event had occurred during any of the past 5 fuel cycles.
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At about 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br />, while comparing fuel cycle 6. actual operating data with the new limits for fuel cycle 7, the engineers identified that the plant had operated in an unanalyzed condition during fuel cycle 6 and may have operated in unanstyzed conditions during fuel cycles 2, 3, 4, and 5.
Investigation of the condition identified that the PRDF event should have been analyzed for power levels between 40 and 80 percent of rated thermal power during fuel cycles 2, 3, 4, 5, and 6 because the impact of PRDF is more limiting than the other events used for octablishing the operating limit for MCPR.
Because the standard margins for uncertainty cnd instrument error for the calculations were not maintained, if a PRDF event occurred while operating near the operating limit for MCPR, the Safety Limit MCPR could have been violated.
During fuel cycle 6, non-conservative power-dependent operating limits for the MCPR were used to monitor the reactor. On several occasions during reactor startups, the reactor was in a condition that placed the MCPR on a few lead fuel bundles close to the power-dependent operating limit for the MCPR.
The power-dependent operating limit for the MCPR would have bacn exceeded if it had been correctly calculated for fuel cycle 6.
Th3 error in the analysis of the power-dependent operating limit for the MCPR has been cpplicable since the first refueling outage (RF-1) when the Maximum Extended Operating Domain (MEOD) modification was implemented.
The MEOD modification eliminated the conservative Total Peaking Factor requirements and replaced them with the power-dependent operating limit for the MCPR.
Th3 Operations Shift Supervisor was notified about the non-conservative power-dependtnt operating limit for the MCPR at about 1545 hours0.0179 days <br />0.429 hours <br />0.00255 weeks <br />5.878725e-4 months <br />.
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NRC FORM 38SA U.S. NUCLEAR RE;ULATORY COMMISSION (4-95)
- LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION F A f'al ITY m me f i t n,wer rT t Ee Nt "---- f W PAnF MI YEAR SEQUENTIAL
" N ON NM Nuunrn Clinton Power Station 05000461 97 001 00 3
OF 5
TEXT W more space is required, use additional copies of NRC Form 366A) l11l Condition Report 1-97-01-030 was initiated to track a cause end corrective action d:tormination for this event.
No cutomatic or manually initiated safety system responses were necessary to place the plent in a safe and stable condition. No equipment or components were inoperable at the ctert of this event to the extent that their inoperable condition contributed to this Ov nt.
CAUSE OF EVENT
Th3 cause of this event is attributed to an error by the nuclear fuel supplier, GE Nuclear En:rgy, in determining which events were the limiting Anticipated operational Occurrences th:t required analysis for the fuel design. The error occurred in the generic design of MEOD which was completed long before its installation at Clinton Power Station (CDS).
Ptsvious CPS reviews of the MEOD modification and fuel design changes did not identify the GE crror. The fuel supplier has informed CPS that it plans to perform a root cause enslysis of the error.
CORRECTIVE ACTION
Corrected power-dependent operating limits for the MCPR will be implemented in the core p rformance monitoring computer and incorporated into the Core operating Limits Report of I
th3 CPS Operating Manual after the fuel cycle 7 Supplemental Reload Licensing Report is cpproved.
ANALYSIS OF EVENT
Thic event is reportable under the provisions of 10CFR50.73(a)(2)(ii)(A) due to the plant b31ng in an unanalyzed condition that could have compromised plant safety.
An casessment of the safety consequences and implications of this event indicated that this Ovsnt had potential nuclear safety significance. The potential to exceed the Safety Limit for the MCPR in fuel cycles 2, 3, 4, 5, and 6 due to a PRDF event was not conservatively enslyzed for conditions between 40 and 80 percent of rated thermal power.
If a PRDF event h:d occurred while operating near the non-conservative power-dependent operating limit for ths MCPR in those fuel cycles, the potential would have existed to exceed the Safety Limit for MCPR for fuel bundles that were near the power-dependent operating limit for the MCPR.
However, CPS has not experienced any Turbine Pressure Regulator Downscale Failure events while operating between 40 and 80 percent of rated thermal power during fuel cycles 2, 3, 4,
5, or 6.
Additionally, at low power levels and at near 100 percent rated thermal power, th3 power-dependent operating limit for the MCPR was adequate.
Further, the reactor was not operated for long periods of time close to the power-dependent operating limit for the MCPR.
Following completion of RF-6, and during fuel cycle 7, the power-dependent operating limit for the MCPR will be correct.
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,U.S. NUCLEAR RELULATORY COMMassioN (a95)
LICENJEE EVENT REPORT (LER)
TEXT CONTINUATION FA, al ITY Mme fil DrW'KFT LER NI""M im PAGF f 31 YEAR SEoVENTML REWSON N W BER NUMMR Clinton Power Station 05000461 97 001 00 4
OF 5
TEXT (tf more space is required, use additional copies of NRC Form 366A) (11l
ADDITIONAL INFORMATION
No squipment or components failed during or as a result of this event.
CPS has not issued LERs for similar events in recent history; however, GE Nuclear Energy h s reported similar fuel design errors regarding the Safety Limit MCPR under the provisions of 10CFR, Part 21.
For further information regarding this event, contact R. W. Chickering, Engineering Projects, at (217) 935-8881, extension 3334.
10CFR, PART 21 REPORT 21-97-003 While performing an approval review of GE Nuclear Energy documentation for the fuel cycle 7 Supplemental Reload Licensing Report and core performance monitoring computer data bank, Illinois Power (IP) determined that there was some potential during the past 5 fuel cycles to exceed the Safety Limit MCPR if a PRDF event had occurred. Review of fuel cycle 6 cetual operating data identified that CPS had operated in an unanalyzed condition during fuol cycle 6 and may have done so in fuel cycles 2, 3, 4, and 5 as well. The cause of this condition is an error in the MEOD analysis performed by CE Nuclear Energy, the nuclear fuel cupplier for CPS.
IP has evaluated this issue and concludes that it is reportable under the provisions of 10CFR, Part 21.
IP is providing the following information in accordance with 10CFR21.21(c)(4).
Initial notification of this matter will be provided by facsimile of this letter to the NRC
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Operations Center in accordance with 10CFR21.21(c)(3) within 2 days of the date the rosponsible officer approves this report.
(i)
Wilfred Connell, Vice President of Illinois Power Company, Clinton Power Station, Post Office Box 678, Clinton, Illinois, 61727, is informing the commission by means of this report.
1 (ii)
The basic component involved in this report is the reload core. The core was to be designed to operate with adequate margins during all conditions as described by the CPS Updated Safety Analysis Report (USAR). This includes the conditions of the MEOD.
one of the conditions the core design must meet is operating limits for MCPR that provide margin to the Safety Limit MCPR for all Anticipated Operational Occurrences between 40 and 80 percent of rated thermal power. The PRDF event is a limiting transient for a region of the MEOD.
j (iii) The reload core designs with the MEOD for fuel cycles 2, 3, 4, 5, and 6 were supplied by GE Nuclear Energy.
NRC f ORM 366A (4-95)
m NR3 FORM 366A U.S. NUCLEAR RECULATORY COMMISiloN (4-95)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION i
FA,'ilITY M m ef1L D,warrT R ER M '"- O im PAf1Ff3)
YEAR stOUENTIAL m s@N NMm NURARfA Clinton Power Station 05000461 97 001 00 5
OF 5
TEXT (11rnore space is required, uso additions / copies of NRC Form 366A) (11l (iv) As discussed in the DESCRIPTION OF EVENT portion of this document, the nature of the defect is the failure of the fuel supplier to include the PRDF event for 40 to 80 percent of rated thermal power in the MEOD analysiP.
If the PRDF event had occurred during any of fuel cycles 2, 3, 4, 5, or 6, while operating near the non-conservative d
powsr-dependent operating limit for the MCPR, the potential would have existed to exceed the Technical Specification Safety Limit MCPR on fuel bundles that were at or j
7 near the power-dependent operating limit for the MCPR.
(v)
GE Nuclear Energy notified CPS about the deficiency in the MEOD analysis in a letter l
dated December 22, 1996.
The letter reported that the GE evaluation of reportability I
under 10CFR, Part 21, concluded that the condition was not reportable. On January 3, 1997, while comparing fuel cycle 6 actual operating data with the new limits for fuel a
cycle 7, IP engineers identified that the plant had operated in an unanalyzed condition during fuel cycle 6 and may have operated in unenalyzed conditions during fuel cycles 2, 3,
4, and 5 as well.
This event was determined to be potentially reportable under the provisions of 10CFR, Part 21 at that time.
(vi) The GE Nuclear Energy letter reports that the deficient reload core analysis applies to Clinton Power Station and other BWR-6 reactor types.
(vii) The corrective action that IP is taking for this event is discussed in the CORRECTIVE ACTION section of this document.
(viii)IP expects that GE Nuclear Energy will notify or has notified affected reactor owners and has no additional advice to offer.
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