ML18059A987

LER 94-009-00:on 940407,identified That Condensate Storage Tank & Primary Coolant Sys Makeup Tank Combined Inventory Below TS Limits.Caused by Inadequate Original Plant Design. Applicable Operating Procedures modified.W/940509 Ltr

ML18059A987
Person / Time
Site:	Palisades
Issue date:	05/09/1994
From:	Rogers D, Smedley R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-009, LER-94-9, NUDOCS 9405160140
Download: ML18059A987 (5)

Text

• " consumers

."' Power David W. Rogers Plant Safety and Licensing Director POWERIN&

/llllCHl&AN'S PRO&RESS Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043 May 9, 1994 Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -

LICENSEE EVENT REPORT 94-009, CONDENSATE STORAGE TANK AND PRIMARY COOLANT SYSTEM MAKEUP TANK COMBINED INVENTORY BELOW TECHNICAL SPECIFICATION LIMITS.

Licensee Event Report (LER} 94-009 is attached. This event is reportable to the NRC per IOCFR50.73(a}(2}(i} as a condition prohibited by the Palisades Technical Specifications.

David W. Rogers Plant Safety and Licensing Director CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades Attachment A CMS' CNER5Y COMPANY

NRC Form 388 IB-831

• LICENSEE EVENT REPORT (LERI

• U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 315~104 EXPIRES: 8/31 /86 FACILITY NAME 111 DOCKET NUMBER 121 PAGE 131 Palisades Plant 015101010121515 1 I OF 0 14 TITLE 141 CONDENSATE STORAGE TANK AND PRIMARY COOLANT SYSTEM MAKEUP TANK COMBINED INVENTORY BELOW TECHNICAL SPECIFICATION LIMITS.

EVENT DATE 151 LER NUMBER 18) REPORT DATE 181 OTHER FACILITIES INVOLVED 18)

SEQUENTIAL REVISION FACILITY NAMES MONTH ~AY YEAR YEAR :1:::1: NUMBER NUMBER MONTH DAY YEAR I

N/A olslololol 0 14 011 9 4 914 01019 o lo 015 ol9 914 N/A olslololol I THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR I: (C'-lc one or more of tJt. followin(IJ 111 l N

OPERATING MODE 181 20.4021bl 20.4051cl 50.731111211ivl 73.71 lbl 20.40511)11 Jfil - 50.3Blcll1 J 50.73111121M 73.71lcl POWER LEVa 20.4051all1 l0il 50.3Blcll2l 50.731all211vii) OTHER !Specify In Abatract 110) 0 0 0 20.40511111 Hiiil -x 50.731111211il 50.7311112llviiillAI below end In Text.

20.40511111 HM

- 50.7311l12Hiil 50. 7 311112llviiillBI NRC Form 3BBAI 20.40511l11lM - 50.731all2Hiiil 50.731all2llxl LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER Richard W. Smedley, Staff Licensing Engineer 6ARIEA1CI°~ I 7 I I I - I s I I I 3 6 4 9 1 I

COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 1131

~~M"I MANUFAC- REPORTABLE MANUFAC-CAUSE SY.STEM COMPONENT TUR ER TO NPRDS CAUSE SYSTEM COMPONENT TUR ER TO NPRDS I I I I I I I I I I I I I I

• • • • • • • • • • • • • • • • • • • • • lli I I I I I I I I I I I I I I L  ?

SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR 1

EXPECTED YES Uf yea. comp#te EXPECTED SUBMISSION llA TEI lxl NO SUBMISSION DATE 115)

I I I ABSTRACT UJmJt II> 1400 .,,.coa, /.o., -imlltflly rtftflon lling,.__. typewritten lineal 11 Bl On April 7. 1994, plant personnel identified that the Technical Specification requirement for maintaining 100,000 gallons of available water in the Condensate Storage Tank ICSTI and Primary Coolant System Makeup Tank (PCSMTI for auxilliary feedwater supply might not have been met at all times during past operation. On April 20, 1994, it was confirmed that the requirement had :

not been met on six occasions in August 1992. To maintain compliance with this requirement, the low level setpoint for the CST

• has been changed to make the operators aware of the available inventory and Procedures will be revised correspondinely.

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NRC Form 388.<. U.S. NUCLEAR REGULATORY COMMISSION 19-83). APPROVEO OMB NO. 3160-0104 EXPIRES: 8/31 /86

,.) LICENSEE EVENT REPORT (LERI TEXT CONTINUATION FACILITY NAME 111 DOCKET NUMBER 121 LER NUMBER 131 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant 0500025594 0 0 9 0 0 0 2 OF 0 ,4, Event Descriotion For certain combinations of initial Condensate Storage Tank (T-21 level, initial Primary Coolant Makeup Tank (T-81) level, plant electrical system status, and operator action time, a total of 100,000 gallons of water would not be available from T-2 and T-8 t This is contrary to the Technical Specification requirement presented in (TS) 3.5.1 e.

During a reexamination of the requirements for Auxiliary Feedwater inventory, the following facts were revealed:

1. From the earliest design phase of the Plant, the combination of T-2 and T-81 was to have sufficient inventory for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of decay heat removal. If T-81 was unavailable and insufficient inventory was available in T-2, any additional, required inventory would come from Lake Michigan via the fire protection system.

2. In Consumers Power's response to Generic Letter 81-21, "Natural Circulation Cooldown," we stated that a conservative estimate of the AFW inventory required to reach Shutdown Cooling initiation was 172,000 gallons. Because this quantity*'

was larger than the Technical Specification required minimum inventory, CPCo stated that we would rely on the Fire Protection System for the additional water. In the Safety Evaluation addressing Consumers Power Company's response (dated 12/15/81 ), the NRC agreed with this position.

3. The adequacy of the AFW inventory was evaluated as part of the Systematic Evaluation Program for Palisades (NUREG- ,.

0820) under Topic Vll-3, "Systems Required for Safe Shutdown.* The evaluation concluded that Palisades did not meet the requirements of GDC 2 and 34 for having enough inventory stored in seismically qualified tanks for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of hot shutdown operation followed by a 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> cooldown to shutdown cooling entry conditions. Alternate calculations (transmitted via a 1 letter dated 10/27 /81 l by the NRC indicated that 107 ,000 gallons of auxiliary feedwater would be sufficient for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of i hot shutdown operation followed by 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of cooldown at 100°F hour. Given that Palisades (at the time) normally kept~:

minimum of 72,000 gallons (-A 54.4%) in T-2. the NRC concluded that the remainder of the AFW inventory could be taken from T-81, or, if T-81 were unavailable, from the fire protection system. This evaluation is part of the licensing basis for Palisades.

4. The Technical Specification requirement to have 100,000 gallons combined between T-2 and T-81 has existed since the initial issuance of the Technical Specifications for Palisades. The exact assumptions and calculations used to derive this number are not available. The basis for the number has always been that it is the inventory required for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of one AFW pump operation for decay heat removal.

(Note: The above discussions explicitly mention the use of the fire protection system as the backup to the condensate storage tank. This is true for AFW pumps P-8A and P-88. For the third AFW pump, P-8C, the suction source backup is the service water system. , This will be implicitly assumed in the rest of this evaluation.)

Additional information, determined that if T-2 and T-81 levels are low enough, it is not possible to transfer, via gravity feed, all of the water in T-81 before T-2 empties (thereby forcing the Plant to use fire water as a source of auxiliary feedwater). This is true for both the 3-inch and the 1.5-inch bypass lines between T-81 and T-2.

In light of this information, it is concluded that the requirements for AFW inventory. as well as Condensate Storage Tank backup, at Palisades are the following:

1. A total of 100,000 gallons of condensate is required to be stored between T-2 and T-81. This water is to be available for :

AFW usage over an eight hour period. Gravity feed is an option for transferring water from T-81 to T-2 if the 3-inch valves:

can be opened normally.

2. A minimum of 57, 100 gallons of water should be maintained in T-2 to meet the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> station blackout requirement. This will alleviate the necessity to gravity feed water from T-81 to T-2 during a station blackout. It will also eliminate the need to use the fire protection system as a backup source for AFW during this event.

NRC Form 3881'. U.S. NUCLEAR REGULATORY COMMISSION 19-83) APPROVED OMB NO. 3160-0104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION FACILITY NAME 11) DOCKET NUMBER 12) LER NUMBER 13) PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant 0 5 0 0 0 2 5 5 9 4 0 0 9 0 0 0 3 OF 0 4

3. Failure of the gravity feed line from T-81 to T-2 (e.g. during a loss-of-offsite power) is equivalent to failure of T-81. In this situation, the fire protection system is the backup water source to T-2. Other sources should be utilized if they are available but the fire protection system is the seismically qualified backup supply.

If an event had occurred that would have required gravity feed from T-81 .to T-2 during a loss-of-offsite power, the operators would have had. to rely on the fire protection system for AFW inventory. This option is covered in SOP 12, wFeedwater System. w Analysis of Event In an effort to determine if any of the above requirements have been violated, a search was performed for historical T-2fT-81 level data. An examination of available historical data (mid-July 1992 to the end of April 19931 indicates that, on six occasions in July and August 1992, T-2 level decreased to less than 60%. The following table indicates the date, approximate level, and Plant status for ,the six events:

Event Date T-2 Level T-81 Level Plant Status 7/16/92 54% 95% On-line 7/20/92 56% 98% On-line 7/27/92 54% 90% Hot Shutdown 8/06/92 58% 92% On-line 8/14/92 51% 98% Hot Shutdown 8/15/92 55% 95% Hot Shutdown Computer calculations were performed for all six cases. The results indicate that available condensate ranged from approximately '

91,000 gallons (8/14/921 to 98,600 gallons (8/6/92). In each case, less than 100,000 gallons was available for AFW usage.

Based on this information, this evaluation concludes that, at least on the dates listed above, the Technical Specification condensate inventory requirements for Palisades were not satisfied.

Additional Deficiency Identified During this evaluation, it was discovered that Plant EOPs, the Tech Data book, the FSAR, and other documents contain the implicit assumption that the entire inventory of T-81 is available whenever it is needed. This is not true for gravity feed between T-81 and T-2. Use of the EOPs, etc. in this situation would lead the operators to overestimate the quantity of auxiliary feedwater available for decay ,heat removal and PCS cooldown. Overestimation of the available AFW supply could place the plant in a situation with T-2 empty prior to the initiation of shutdown cooling. In this case, the operators would have the option of using the fire protection system or the service water system as a suction source for the AFW pumps, thereby averting any loss of PCS heat removal capability. In spite of this, the failure of Plant procedures and design documents to recognize a basic limitation of the AFW supply system is considered a deficiency.

Cause of Event The root cause of the identified deficiency appears to be two-fold. First, the original design of the Plant is inadequate when it comes to gravity transfer between T-2 and T-81. This mode of operation has been recognized since Plant construction and yet has apparently never been validated or analyzed. Gravity feed between T-81 and T-2 was just assumed to be sufficient for Auxiliary f eedwater requirements.

The second root cause appears to be a lack of a questioning attitude towards a minor discrepancy in the plant configuration.

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Form 3881', U.S. NUCLEAR REGULATORY COMMISSION .

• (B*BJI APPROVED OMB NO. 3160-0104 EXPIRES

  8/31 /86

,) LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER !31 PAGE (4)

SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant 0 5 0 0 0 2 5 5 9 4 0 0 9 0 0 0 4 OF 0 4 Corrective Actions

1. Modify plant operating procedures to ensure a minimum of 57, 100 gallons of water in T-2, as well as a minimum of 100,000 gallons of water in T-2 and T-81 combined.

2. Ensure that 100,000 gallons of water can be transferred from T-2 and T-81 over an eight hour period.

3. Change T-2 low level setpoint to be consistent with the required levels and update any required procedures.

4. Change the Emergency Operating Procedures to correctly reflect the relationship between total inventory and available inventory for T-2 and T-81, especially when gravity feed is considered.