ML20246M368

Significant Deficiency Rept L2-89-06 Re Unavailability of Suppression Pool Indication Due to App R Fire.Caused by Design Error Resulting from Lack of Procedural Guidance. Reportability Evaluation Initiated

ML20246M368
Person / Time
Site:	Limerick
Issue date:	05/08/1989
From:	Kowalski S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Russell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
GL-86-10, IEIN-84-09, IEIN-84-9, L2-89-06, L2-89-6, NUDOCS 8905190108
Download: ML20246M368 (5)

Text

.

PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 PHILADELPHIA A. PA.19101 (215) 841 4502 S. J. KQWALSKI May 8, 1989 vic e-en esio s ur

.m.n...........

Mr. W. T. Russell, Administrator 10CF.

.55Ce)

United States Nuclear Regulatory Conmission Docket No. 50-353 Attn: Document Control Clerk CPPR-107 Mall Station Pl~137 Washington, DC 20555

Subject:

Limerick Generating Station Unit 2 Significant Deficiency Report Unavailability of Suppression Pool Indication Due to an Appendix R Fire.

Reference:

Telephone Conference between PECo Nuclear Engineering (W. J. Boyer) and NRC (H. Williams) dated l

April 5, 1989.

l l

Flie:

QUAL 2-10-2 (SDR-L2-89-06)

Dear Mr. Russell:

As promised in the Reference above, we are submitting the attached Significant Deficiency Report which provides a description of the subject concern, and a status report of our completed and ongoing activities.

As part of a self-assessment, PECo is performing a root cause evaluation of all suspected deficiencies with the LGS safe shutdown analysis as conmitted to in the LGS Fire Protection Evaluation Report (FPER). The results of this assessment should reveal if these norconformances are programmatic errors or Isolated deficiencies.

Based on this assessment, corrective actions to prevent recurrence will be identified.

PECo shall provide a response discussing the results of this assessment and the proposed corrective actions oy May 31, 1989.

If you have any further questions at this time, please contact us.

j5 09050s Y'

S 0500

~

l BLS/ds/01268902 Attachment Copy to:

W. T. Russell, USNRC, Region I Administrator R. A. Granm, USNRC, LGS 2 Senior Resident Inspector Ng R. J. Clark, USNRC, LGS 2 Project Manager Marty McCormick g

L

.4 NUCLEAR ENGINEERING ENGINEERING DIVISION N2-1, 2301 MARKET STREET SIGNIFICANT DEFICIENCY REPORT NO. L2-89-06 UNAVAILABILITY OF SUPPRESSION POOL INDICATION DUE TO AN APPENDIX R FIRE NRC CONSTRUCTION PERMIT NO. CPPR-107 Description of Deficiency As a result of engineering reviews of the ability of Limerick Generating Station to safety shut down in the event of a fire, it was determined that the lack of suppression pool level Indication to support shutdown Methods A, B, C, D, and R, and lack of suppression pool tenverature indication to support shutdom Method P, could have adversely impacted the operator's ability to properly assess suppression pool conditions in the event of an Appendix R fire.

In May, 1989, an engineering review Indicated that a fire concurrent with a loss of off-site power would cause a loss of suppression pool temperature Indication at the Rerrote Shutdown Panel (RSP).

In July, 1988,-an engineering review determined that suppression pool level Indication was also necessary to support safe shutdown of the plant in the event of a fire.

This event was not reported In a timely manner due to a procedural inadequacy which has been corrected.

An evaluation was initiated in January, 1989 to determine the deportability of this condition. This condition was determined not to be reportable by station personnel at that time due to a misunderstanding of the regulatory requirements in that the terminology " safe shutdown condition" was asstmed to refer to hot shutdown rather than cold shutdown condition. The lack of suppression pool level and temperature does not impact the capability to achieve hot shutdown. The Fire Protection Evaluation Report (FPER) Section 5.2.3 Indicates that there is arple time (longer than 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />) before suppression pool heatup necessitates operation of the Residual Heat Removal system. This statement was taken to mean that suppression pool level and teriperature would remain acceptable under all conditions of Appendix R while achieving hot shutdown. However, the timing and secuence of actions and equipment failures could impact the suppression pool level / temperature versus time. As a result, monitoring of suppression pool temperature (and level to a lesser degree) at the RSP may be necessary for descision making under Appendix R assumptions while achieving cold shutdown.

Safety implications The safety concern associated with the ability of the operators to monitor suppression pool level and temperature is that primary containment and reactor coolant system Integrity cre maintained.

3

. l Suppression pool level ensures the availability of the suppression pool as a heat sink to condense steam from the reactor vessel, while suppression pool temperature ensures that sufficient heat capacity is available in the suppression pool to accept the heat load fran the reactor vessel. These safety functions must be available to achieve and maintain the reactor in a cold shutdown condition using any of the shutdaan methods described in the FPER.

If the miniman necessary suppression pool wat er volume is known to exist prior to the occurrence of a fire, there is a high degree of assurance that this volune will remain available throughout the system operations that will be relied on for achieving cold shutdown. Although the High Pressure Coolant Injection (HPCI), Reactor Core Isolation Cooling (RCIC) and RHR pumps take suction from the suppression pool, the water is returned to the suppression pool either directly or by indirect means (i.e.,

through the reactor vessel).

The valves that are relied on to maintain the proper flow paths in these three systems are considered to be safe shutdown canponents, and the electrical cables for the valves are protected from the effects of postulated fires as ner.essary to ensure system operability. Although a moderate-energy pipe crack in piping connected to the suppression chamber could result in the loss of water from the suppression pool, such an occurrence is not postulated to occur simultaneously with a fire in the plant. This position is consistent with the NRC quidance contained in Branch Technical Positions ASB 3-1 and CMEB 9.5.1.

As a result, there is no postulated event or combination of events that would result in a significant loss of water volume fran the suppression pool during a fire.

Suppression pool temperature is used to estabilsh cooling to the suppression pool prior to exceeding allowable temperature limits.

Based on operator training and experience, in the event of loss of suppression pool temperature indication, operators would initiate suppression pool temperature cooling as soon as practicable.

Additionally, the operators could take temporary pool temperature readings using portable test equipment connected to spare temperature elements of the Suppression Pool Temperature Monitoring System (SPTMS). This activity is governed by an existing procedure.

The existing suppression pool level indication in the Main Control (MCR) and at the RSP is not listed in the FPER and it was not included in the original SSD analysis, therefore, the associated cabling and l

Instrumentation are not protected f rom fire damage such that suppression l

pool level Indication would not be available in the event of a fire.

The existing suppression pool temperature indication, at the RSP in not listed in the FPER and therefore the associated cabling was not protected from fire damage such that the suppression pool temperature tr' cation would not be available in the event of a fire.

_3_

A PECo self assessment of the LGS Safe Shutdown (SSD) analysis is being performed to determine the root cause of previous similar occurrences I

concerning deficiencies In SSD capabilities as conmitted to in the FPER.

Preliminary results of the assessment show that the root cause is two fold:

1) a lack of detailed procedures utilized in performing the SSD analysis, and 2) a misunderstanding and misapplication of the detailed regulatory requirements, due in part to the changes in interpretation over the course of licensing the Limerick Generation Station. The root cause of the conditions described in this LER ccme under these same causes.

The root cause for not including suppression pool level Indicatton in any safe shutdown method was a design error as a result of a misunderstand!ng of the intent of the regulatory guidance provlded in Information Notice 84-09 and GL 86-10.

Information Notice 84-09 stated that the NRC staff considered suppression pool level indication necessary to achieve safe shutdown in the event of a fire.

An evaluation was performed at that time which Justified not providing suppression pool level indication due to the results which showed minimal changes in the suppression pool level during shutdown following a fire. GL 86-10 recognized that suppression pool level would not change significantly during emergency shutdown conditions, but Indicated that suppression pool level indication was necessary for the operator to confirm the availability of the suppression pool as a heat sink.

I The root cause for not including suppression pool temperature indication in shutdown Method R is a design error resulting from the lack of procedural guidance and detailed SSD analysis criteria.

Instrumentation to monitor suppression pool temperature was included in the analysis of safe shutdown capability for shutdown Methods A, B, C, and D.

The Instruments selected for use with these shutdown methods are listed in Tables A-8 through A-11 of the FPER. However, due to inconsistency in performing the SSD analysis, instrumentation for nonitoring suppression pool temperature was not listed in FPER Table A-23, the corresponding table for shutdown Method R.

Method R is relied upon for fires occurring in the control complex, such that the RSP must be used to maintain control of the necessary safe shutdown systems. The instruments that are located on the RSP are Identified in Final Safety Analysis Report (FSAR) Table 7.4-3 As listed on page 8 of this table, RHR punp suction temperature Indicator TI-51-204A is provided to allow monitoring of suppression pool temperature form the RSP. Section 7.4.2.4.2.2 of the FSAR Indicates that the RSP was originally designed to satisfy General Design Criteria (GDC)-19, " Control Room," of 10 CFR 50, Appendix A, and not fire protection requirements. Additionally, the comparison of the LGS design to NRC fire protection guidance provided in Information Notice 84-09, conducted in 1984, and to GL 86-10, conducted in 1987, failed to recognize that suppression pool temperature was not included in the list of safe shutdown components to support shutdown Method R.

_4_

I 1

The root cause of the failure to recognize the unavailability of suppression pool temperature Indication for safe shutdown from the RSP in the event of a fire in the control canplex is a design error during the original SSD analysis. The original analysis failed to recognize that tanperature indicator TI-51-204A is non-safety related and is poaered fran a non-Class 1E 120V instrunent AC distribution panel and would be lost as result of the loss of all AC power.

The SSD analysis described in Section 5.2 of the FPER recognizes the need for manual actions to restore AC power. These nanual actions are part of existing plant procedures that support safe shutdown in the event of a fire.

However, the original antlysis failed to recognize that this temperature indication would be unavailable until the appropriate manual actions to restore AC power are accomplished.

Additionally, the original SSD analysis failed to recognize that the suppression pool temperature indication would be unavailable due to the lack of flow in the RHR pump suction line in the event of a loss of all AC power, since the RHR punps will not be operating until the nanual actions are taken to restore AC power.

Corrective Actions In accordance with the PECo Deportability Evaluation Process, a deportability evaluation was initiated. On April 6, 1989, the condition was reported to the NRC as a 10CFR50.55(e) reportable condition.

The scope of the deficiency also includes Unit 1.

This condition required prompt notification on April 5, 1989 which was followed by LER 89-023 on May 5, 1989. Permanent modifications were performed on Unit 2 to provide safety-related suppression pool level indication to support all safe shutdown nethods and to add safety-related suppression pool temperature instrumentation at the RSP to support shutdown Method R.

Action To Prevent Recurrence PECo is performing an assessment of the LGS Safe Shutdown (SSD) analysis to determine the root cause of recent LERs written against the l

l SSD capabilities as cannitted to in the LGS FPER.

The results of the l

assessment will identify if the non-confonnances in the LERs are programmatic errors or isolated deficiencies.

PECo shall provide a response discussing the results of this assessnent and the proposed corrective actions by May 31, 1989.

l l

l GBH/kh/05018903 l

l l

L _ _ ____ _ _ _ ________________ _ __ ___________________________ ___________________________ ______________________ _______ ___________________ ____ ____.___ _______ __