United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #: 9702030199

                       LICENSEE EVENT REPORT (LER)



FACILITY NAME: Clinton Power Station                      PAGE: 1 OF 5



DOCKET NUMBER:  05000461



TITLE:  Failure of Nuclear Fuel Supplier to Analyze Turbine

        Pressure Regulator Downscale Failure Event in the Off-

        Rated Condition Results in Operation in an Unanalyzed

        Condition



EVENT DATE:  01/03/97   LER #:  97-001-00   REPORT DATE:  01/28/97



OTHER FACILITIES INVOLVED:  None                    DOCKET NO:  05000



OPERATING MODE:  5   POWER LEVEL:  000



THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR

SECTION:

50.73(a)(2)(ii) & OTHER



LICENSEE CONTACT FOR THIS LER:

NAME:  R. W. Chickering, Engineering        TELEPHONE:  (217) 935-8881,

       Projects                                         Extension 3334



COMPONENT FAILURE DESCRIPTION:

CAUSE:      SYSTEM:       COMPONENT:       MANUFACTURER:

REPORTABLE NPRDS:



SUPPLEMENTAL REPORT EXPECTED:  NO



ABSTRACT:



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 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.



END OF ABSTRACT



TEXT                                                          PAGE 2 OF 5



DESCRIPTION OF EVENT



On January 3, 1997, the plant was in Mode 5 (REFUELING) and the sixth

refueling outage (RF-6) was in progress.  Reactor [RCT] coolant

temperature was being maintained between 75 and 185 degrees Fahrenheit

and pressure was atmospheric.



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 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 occurrence.  This condition is

unique to the Boiling Water Reactor (BWR)-6 reactor type because a single

failure may cause the pressure regulation system to fail downscale.



The fuel supplier issued a revision to the power-dependent operating

limit for the MCPR for fuel cycle 7 to correct the previous limit which

was not adequate for conditions between 40 and 80 percent of rated

thermal power in the PRDF event.  Utility engineers were performing an

approval review of the fuel supplier documentation for the fuel cycle 7

Supplemental Reload Licensing Report and the core performance monitoring

computer [CPU] [IO] data bank.  ,The 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.



At about 1520 hours, 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 unanalyzed 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 establishing the operating

limit for MCPR.  Because the standard margins for uncertainty land

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 been exceeded if it had been correctly calculated for fuel

cycle 6.



The error in the analysis of the power-dependent operating limit for the

MCPR has been applicable 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.



The Operations Shift Supervisor was notified about the non-conservative

power-dependent operating limit for the MCPR at about 1545 hours.



TEXT                                                          PAGE 3 OF 5



Condition Report 1-97-01-030 was initiated to track a cause and

corrective action determination for this event.



No automatic or manually initiated safety system responses were necessary

to place the plant in a safe and stable condition.  No equipment or

components were inoperable at the start of this event to the extent that

their inoperable condition contributed to this event.



CAUSE OF EVENT



The cause of this event is attributed to an error by the nuclear fuel

supplier, GE Nuclear Energy, in determining which events were the

limiting Anticipated Operational Occurrences that 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

(CPS).  Previous CPS reviews of the MEOD modification and fuel design

changes did not identify the GE error.  The fuel supplier has informed

CPS that it plans to perform a root cause analysis of the error.



CORRECTIVE ACTION



Corrected power-dependent operating limits for the MCPR will be

implemented in the core performance monitoring computer and incorporated

into the Core Operating Limits Report of the CPS Operating Manual after

the fuel cycle 7 Supplemental Reload Licensing Report is approved.



ANALYSIS OF EVENT



This event is reportable under the provisions of 10CFR50.73(a)(2)(ii)(A)

due to the plant being in an unanalyzed condition that could have

compromised plant safety.



An assessment of the safety consequences and implications of this event

indicated that this event 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 analyzed for

conditions between 40 and 80 percent of rated thermal power.  If a PRDF

event had occurred while operating near the non-conservative

power-dependent operating limit for the 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, the 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.



TEXT                                                          PAGE 4 OF 5



ADDITIONAL INFORMATION



No equipment 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 has 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

actual operating data identified that CPS had operated in an unanalyzed

condition during fuel 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 GE Nuclear Energy, the nuclear fuel supplier 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 Operations Center in accordance

with 10CFR21.21(c)(3) within 2 days of the date the responsible 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.



(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.



(iii)     The reload core designs with the MEOD for fuel cycles 2, 3, 4,

          5, and 6 were supplied by GE Nuclear Energy.



TEXT                                                          PAGE 5 OF 5



(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 analysis.  If the PRDF event

          had occurred during any of fuel cycles 2, 3, 4, 5, or 6, while

          operating near the non-conservative power-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 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 dated December 22, 1996.  The letter

          reported that the GE evaluation of reportability 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 cycle 7, IP 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 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.



ATTACHMENT TO 9702030199                                      PAGE 1 OF 1



                                                  Illinois Power Company

                                                  Clinton Power Station

                                                  P.O. Box 678

                                                  Clinton, IL 61727

                                                  Tel 217-935-5623

                                                  Fax 217-935-4632



                              WC-075-97

                              January 28, 1997    Wilfred Connell

                                                  Vice President



ILLINOIS

     POWER                                             U-602685

                                                       2C.220



Docket No. 50-461                            10CFR50.73

                                             10CFR21.21

Document Control Desk

Nuclear Regulatory Commission

Washington, D.C. 20555



Subject:  Clinton Power Station - Unit 1

          Licensee Event Report No. 97-001-00

          and 10CFR, Part 21 Report.No. 21-97-003



Dear Madam or Sir:



     Enclosed is Licensee Event Report (LER) No. 97-001-00 and 10CFR,

Part 21 Report No. 21-97-003: Failure of Nuclear Fuel Supplier to Analyze

Turbine Pressure Regulator Downscale Failure Event in the Off-Rated

Condition Results in Operation in an Unanalyzed Condition.  This report

is being submitted in accordance with the requirements of 10CFR50.73 and

10CFR21.21.



                                        Sincerely yours,



                                        Wilfred Connell

                                        Vice President



RSF/krk



Enclosure



cc:  NRC Clinton Licensing Project Manager

     NRC Resident Office, V-690

     Regional Administrator, Region III, USNRC

     Illinois Department of Nuclear Safety

     INPO Records Center

     GE Nuclear Energy



*** END OF DOCUMENT ***







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