NRC-89-0260, LER 89-021-01:on 890906,35 of 237 Containment Isolation Valves Exceeded Administrative Allowable Leakage Rate When Tested.Caused by Normal Wear & Degradation During Specified Time Interval.Valves Cleaned & repaired.W/891221 Ltr

LER 89-021-01:on 890906,35 of 237 Containment Isolation Valves Exceeded Administrative Allowable Leakage Rate When Tested.Caused by Normal Wear & Degradation During Specified Time Interval.Valves Cleaned & repaired.W/891221 Ltr

ML20011D623
Person / Time
Site:	Fermi
Issue date:	12/21/1989
From:	Nader G, Orser W DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-89-0260, CON-NRC-89-260 LER-89-021, LER-89-21, NUDOCS 8912280116
Download: ML20011D623 (6)

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December 21 1989 -j NRC-89-0260 1 I

U. S. Nuclear Regulatory Commission  ;

Attention: ~ Document Control Desk

. Washington, D.C. 20555

Reference:

(1) Fermi 2 NRC Docket No. 50-341 Facility Operating License No.-NPF-43 (2) Transmittal of Licensee Event Report. r

. 89-021-00, dated October 6.-1909.

NRC-89-0185

Subject:

-Licensee Event-Report (LER) No. 89-021-01  ;

Please find' enclosed LER No. 89-021-01.. dated. December .

21. 1989, for a reportable event that occurred on' l September 6. 1989. . A supplement is being submitted to-7 report final results of Type A. B. and C testing and the corrective actions for Type B E C testing failures as reported in the original LER. A copy of this LER is.also being sent to the Regional Administrator. USNRC Region III.

If you have any questions, please. contact Gordon Nader at (313) 586-4513.

I Sincerely, y ~ <

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Enclosure:

NRC Forms 366. 366A l cc: A. B. Davis l

J. R. Eckert l

R. W. Defayette/W. L. Axelson W. G. Rogers J. F. Stang Wayne County Emergency -

Management Division 8912280116 PDR 891221 S

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APPRovto OMS No 3106 4104 LICENSEE EVENT REPORT (LER) '"a'*8"

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Periodic leakage rate testing of Containment-Isolation valves and penetrations in accordance with the requirements contained in Technical Specification 3.6.1.2 and 10 CPR 50 Appendix J. has'been completed. During the performance of this testing, several valves have exceeded their administrative allowable leakage ratec and their combined leakage exceeded the limits as defined in the i

subject Technical Specification Limiting Ccadition for Operation.

Thirty-five out of the 237 containment isolation valves l exceeded their administrative individual allowable leakage rate. l-They were disassembled. cleaned. repaired or reworked, and l ,

retested as appropriate. An Integrated Leakage Rate Tect was l  !

successfully completed on November 21, 1989. l l

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• U.S. l'UCLEAR 5.tEULATORY COMh408 0N

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_;, ess .dpooner Nag Asse asAw (th Initial Conditions:

t operational Condition: 5 (Ref ueling)

Reactor Power 0%

reactor Pressure O psig Reactor Temperature: 97 degrees Fahrenheit Description of Event:

On November 21, 1989, the Integrated Leak. Rate-Test (ILRT) was l

-completed following earlier performance of'the Local Leak Rate l Testing (LLRT) of Primary Containment Isolation Valves (ISV) l-and Penetrations'in accordance with Technical: Specifications l (TS) 3/4.6.1.2. " Primary Containment Leakage" and 10CFR50 l Appendix J. " Primary Reactor Containment Leakage Testing for -

l Water Cooled Power Reactors". Of the 237 valves tested. 35 .l. .

contributed significantly to the total combined leakage of the -l primary containment boundary. Included in thi's total are the- l Main Steam Isolation Valves (MSIVs). l TS 3.6.1.2.a requires that the allowed primary containment l 1eakage-rate (La) be limited to 0.5 percent by weight of the l-containment air per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (wt%/ day) at 36.5 psig. After l rework of the 35 valves the measured Type A test result was l 0.318 wt%/ day which is within the acceptance criteria-of 0.375 l wt%/ day (0.75 La). l' Surveillance Requirement 4.6.1.2.a.2 requires that if Type B.& l C tests are conducted prior to the Type A test. then the Type. l' A test result shall have added to'it the difference between the l "as_found" vs. "as lefr" leakages for all penetrations. The _l "as found" vs. "as left" difference, including the MSIV's and l MSIV Leakage Control System, was 0.640 wt%/ day. Adding the' l-difference to'the measured Type A test results of 0.318 wt%/ day 1 results in an "as found" conteinment leakage rate of 0.958 I wt%/ day. l TS 3.6.1.2.b requires that the-combined leakage rate of Type B l and Type C tests, except f or leakage . tests on the MSIVs and l

-vcives which are hydrostatically tested, shall-be less than or l-equal to 0.60 La. Exclusion of MSIV leakage in the combined l

. total (0.60 La) is an approved exemption from 10 CFR 50 l Appendix J. Based on initici testing..two~ Type B tests andr35 l.

Type C.. tested valves exceeded their individual' administrative l limits. . Administrative limits are established for Type B and C l Jageoau mea .u.s. cro, a...- m e m. m a

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tests in accordance with the Inservice Test. Program to provide 'l~

' individual valve and penetration acceptance criteria. The l combined leakage from Type B and~C Tests exceeded-0.60 La after 1 initial testing. l TS 3.6.1.2.c requires that the leakage rates for all four main i steam lines..when tested at 25.0 psig, be less than or equal to l .

100 Standard Cubic Feet per Hour (SCFH). LLRTs of the HSIVs l resulted in these valves exceeding their TS limit of 100 SCFH. l-  ;

TS 3.6.1.2.d requires.that a combined leakage ~ rate.for all l' l containment isolation valves in hydrostatically tested lines be. l 1ess than or equal to 5 gallons per-minutes (gpm) when tested at 'l 1.10 Pa. The combined _ local leakage rates of-hydrostatically- l tested valves exceeded the 5 gpm TSLlimit.. l Additionally. TS 3. 6.1. 2. e requi'res that the water leakage.be l-

less than or equal to lgpm times the number of valves per l penetration not to' exceed 3 gallons per minute (gpm) per: l penetration for any line penetrating containment when l hydrostatically tested at 1.10 Pa. One valve in a' penetration l l

leaked in excess of the 3 gpm TS limit. l .

The post ILRT Report (required by 10CFR50, Appendix J) will l-specify the as found and as left individual-leakege rates for 1 all valves / penetrations. l Cause of the Events t The basis for the associated TS-survelliance requirement is to 1 detect valve leakage due to normal wear and-degradation during a l specified. time interval.- l The observed containment isolation valve leakage was generally .l caused by normal degradation of valve components and/or l l contaminants on the valve seating surfaces._ One exception was -l L identified where an MSIV Leekage Control Valve, B21-F434, I l

1eaked 155 SCFH (0.52 La). This valve failed to fully close l due to binding of the valves' internals. l Analysis of the Event:

I ' Type A test leakage.is to a large degree a measure of the 'l individual penetration leak tightness. The MSIVs and MSIV l Leakage-Control System valve leakage was a maj or contributor l to~ the "as-found" Type A test results. I i

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4 NaC tem aneA' UL NUCLEAR LETULATORY COMMtIDION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION' =>Psovto oMe No 3ino-om -

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0l2l 1 - 0l 1, 44 OF 0l 5 The Fermi MSIV Leakage Control System (MSIVLC) eliminates l~

leakage through the MSIVs by pressurizing the space between 'l the inboard-and outboard MSIVs and the outboard and third MSIV l to slightly above containment post-LOCA accident pressure. The l Design Basis LOCA is_ the most limiting accident with respect to l containment pressurization and off-site dose consequences. l This system meets the guidelines of Regulatory Guide l'.96 and l therefore, meets the requirement of General Design Criterion 54 l as it relates to leak detection, isolation, containment' I capabilities and suitable redundancy. l Since operations personnel are directed.to initiate the MSIV l Leakage control System shortly after a LOCA. leakage from l

ontainment out through the MSIVS and MSIVLC valve'would have l been zero. The "as-found" containment leakage ~ rate with the- l HSIVLC system operating would be 0.405 wt%/ day which is below l the TS 3.6.1.2.a limit of 0.5 wt%/ day. Following an accident. 1 Standby Gas Treatment System (SGTS) would filter the gaseous 1 effluent from the Reactor Building' prior to its release, which I would significantly reduce the potential off-site doses- l attributable to leakage from primary containment. l l

Type B and C LLRT is performed to detect degradation of l penetration and valve sealing characteristics which would l L adversely affect primary containment: integrity. Any degrada- l tion discovered through testing is corrected so that1 potential- l degradation of conteinment or containment penetrations does not l occur between the Type A. B and C testin8 Periods. While the' I combined B and C leakage exceeded.the 0.60 La maximum allowed. I by T.S., the net containment leakage with the-MSIVLC system in- .I operation was less_than the maximum allowable containment leak- l age rate of 0.5 wt%/ day. l-Two valves were primarily responsible for exceeding both T.S. .I requirements (TS 3.6.1.2.d and 3.6.1.2.9) for water leakage. 'l One valve was the Residual Heat Removal (RHR) "A" minimum flow l'  :!'

isolation valve and the other was the: Torus Water Management l' System (TWMS)-inboard isolation. valve. RHR is considered a l~

l closed system outside of containment and is also running l f~ post-LOCA. Any water leakage through the isolation valve would l l be contained-in the RHR process piping. I i

The TWMS isolation valve had a second isolation valve down-- l stream of it that was leaktight. This second isolation valve l

' would have contained any Torus water from leaking out of l-containment. Therefore, substantive barriers existed to prevent l 1eakage from both Primary Containment-water leakage paths. l  ;

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.3 Corrective Actions: ,

All 35 containment isolation valves that exceeded their I administrative individual allowable leakage rate, including l B21-F434 were cleaned, reworked and/or refurbished. The valves l were then retested and leakage verified to be in compliance- l with Technical Specification Surveillance Requirement 4.6.1.2. l The f our outboard MSIVS were- disassembled. refurbished. _ l reassembled. and successfully retested. The four inboard MSIVs l ,

were modified during the current refueling outage using the -l manufacturer's latest design modification kit. This MSIV l modification has been endorsed by the BWR Owner's Group and the  !

NRC. and consists of-:hanges that include an elongated poppet l- .

and pilot poppet assembly (" nose cone"). addition of an l anti-rotation device and a2 inch diameter stem with associated' I machining of the valve cover / bonnet. These modifications-are l' intended to improve LLRT performance and' valve reliability. l The MSIVLC is designed to eliminate leakage from_ containment l 1 '

through the MSIVS. The MSIV leakage was within'the capacity of l the MSIVLC system, therefore, even though the valves-exceeded I their T.S. leakage limit, potential off-site doses dueEto this _l 1eak path were eliminated. l The following table summarizes the present condition and test I results of the primary containment isolation valves and I penetrations. l Technical l Type of_ Test As-Left Condition Specification Limit l l

Type B and C

• 86.09 SCFH 178 SCFH (0.3 wt%/ day) l (0.145 wt%/ day) l l

MSIVs 24.98 SCFH 100 SCFH l l

Hydrostatic 1.22 GPM 5 GPM l 0 For all containment isolation valves exclusive of the MSIVs and l Hydrostatically tested valves. l 1

Provious_Similar Occurrences:

Licensee Event Report 86-011-01 " Excessive Leakage from MSIV" and Licensee Event Report 88-008-01 " Leakage In Excess of the Allowable Found-During LLRT".

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