D]~i~BUTION. DEMONSTRA,TION SYSTEM61

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8812160008 DOC.DATE: 88/12/09 NOTARIZED: NO DOCKETFACIL:50-275 Diablo Canyon Nuclear Power Plant, Unit 1, Pacific Ga 05000275

AUTH.NAME - AUTHOR AFFILIATION,.MALONE,D.D. Pacific Gas & Electric Co.SHIFFER,J.D. Pacific Gas & Electric Co.

RECIP.NAME -'ECXPIENT AFFILIATION. R

SUBJECT: LER 88-028-01:on 881014,entry into TS 3.0.3 when 2 of 4MSIVs inoperable due to inadequate EQ of components.

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DISTRIBUTION CODE IE22D COPIES RECEIVED:LTR ENCL SXZE-TXTLE: 50.73 Licensee Event Report (LER), Incident Rpt, etc.NOTES:

RECIPXENTID CODE/NAME

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On October 14, 1988, at 2015 PDT, the shift foreman declared two of the four Hain SteamIsolation Valves (HSIV) for each unit inoperable due to inadequate environmentalqualification (EQ) of surge suppressors. Unit 1 failed to satisfy

Technical'pecification(TS) 3.7.1.5 and entered TS 3.0.3. An Unusual Event was immediatelydeclared and the 1-hour report required by 10 CFR 50.72(a)(1)(i) for Unit 1 and the4-hour report required by 10 CFR 50.72{b)(2){i) for Unit 2 vere made at 2015 PDT.-

On October 14, 1988, at 2114 PDT, Unit 1 initiated an orderly shutdown in accordance withthe requirements of TS 3.0.3.

On October 14, 1988, at 2347 PDT, a design change removing the surge suppressors wascompleted. The HSIVs were declared operable, TS 3.0.3 was exited and the Unusual Eventwas terminated.

The root cause of this event was personnel error, cognitive, by PGhE engineeringpersonnel, in that the qualification of surge suppressors was not addressed in EQ files.A contributory cause vas an error of classification of the HSIVs in a September 1981 EQ

report, which assumed the solenoids were de-energize to vent.

To prevent recurrence of this event, all EQ files vill be revised to include specifictermination requirements; the appropriate engineering procedures will be revised; andresponsible engineers will be further instructed regarding EQ procedures.

440S/0066K 8812il0008 S-'209PDR ADOCK 0500027'59 PDC

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Unit 1 was in Hode 1 (Power Operation) at 100 per cent power when this eventwas identified.

Unit 2 was in Hode 6 (Refueling) when this event was identified.

A. Event:

On October 13, 1988, at approximately 1900 PDT, the plant environmentalqualification (EQ) coordinator identified a deviation regarding requiredelectrical connections specified on a corrective maintenance work orderfor Unit 2 refueling maintenance'activities. The EQ coordinator informedplant management and engineering of the "as found" condition of theelectrical connection. An imnediate engineering evaluation of theconnection was requested. On October 14, 1988, at approximately 1900 PDT,the Plant Safety Review Committee (PSRC) was presented an engineeringevaluation of the "as found" electrical connection for the Hain SteamIsolation Valves (HSIV)(SB)(FCV). This electrical connection incorporateda terminal b'lock connection located inside a one and one quarter inchconduit connector (condulet) which contained an electrical surgesuppressor across the terminal connections for the solenoid controlvalves. Two of the four HSIVs, FCV-43 and FCV-44, are located outside ofthe containment structure but within the auxiliary building, (areas GE andGH) and may be sub)ect to a harsh environment as a result of a postulatedHigh Energy Line Break (HELB). FCV-41 and FCV-42 are located outside theplant buildings (area FH) and are not subject to a harsh environment dueto a postulated HELB accident.

Therefore two of the four HSIVs may be required to operate in a harshenvironment during a postulated HELB accident. However, the existingqualification documentation did not address the use of surge suppressorsfor this type of installation.

On October 14, 1988, at 2015 PDT, the PSRC directed the Shift Foreman todeclare HSIVs FCV-43 and FCV-44 inoperable for Units 1 and 2. TechnicalSpecification (TS) 3.7.1.5 requires FCV-41 through FCV-44 to be operablein Hode 1. Hith two of the four required HSIV valves inoperable, thelimiting condition for operation (LCO) was not met. Unit 1 entered TS3.0.3 and an Unusual Event was declared. The 1-hour non-emergency reportrequired by 10 CFR 50.72(a)(i) was made at 2015 PDT. Unit 2, which wasdefueled for the second refueling outage, was determined to be in a safecondition and the 4-hour non-emergency report required by 10 CFR

50.72(b)(2)(i) was made at 2015 PDT.

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On October 14, 1988, at 2114 PDT, plant operators initiated an orderlyshutdown'of Unit 1, as required by TS 3.0.3.

On October 14, 1988, at 2347 PDT.plant Naintenance personnel completedremoval of the'surge suppressors for FCV-43 and FCV-44 protection train B,Unit 1, in accordance with design change DC1-EE-41351. The protectiontrain B control solenoid valves were declared operable. The requirements

'of TS 3.0.3 were exited, and the Unusual Event was terminated.

B. Inoperable components or systems that contributed to the event.

None.

C. Dates and approximate times for ma)or occurrences.

l. October 13, 1988, at 1900 PDT: Discovery Date. The plant EQcoordinator ident)fied thediscrepancy between designdocuments and field

conditions.'.

October 14, 1988, at 1900 PDT:

3. October 14, 1988, at 2015 PDT:

The PSRC was presented PGLE'sengineering evaluation of the "asfound" configuration anddetermined the HSIVs to beinoperable.

Event Date. HSIV valves FCV-43and FCV-44 were declaredinoperable for Units 1 and 2.

TS 3.7.1.5 was not met for Unit 1

and TS 3.0.3 was entered.

4. October 14, 1988, at 2015 PDT: Plant operators declared anUnusual Event and the 1-hournon-emergency report required by10CFR50.72(a)(i) was Nade forUnit l.

5. October 14, 1988, at 2015 PDT:

6. October 14, 1988, at 2114 PDT:

The 4-hour non-emergency reportrequired by, 10CFR50.72(b)(2)(i)was made for Unit 2.

Plant operators initiated anorderly shut down of Unit 1 asrequired by TS 3.0.3.

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7. October 14, 1988, at 2347 PDT: - The surge suppressors wereremoved, HSIVs tested, anddeclared operable.- The UnusualEvent vas termfnated for Unit l.

D. Other. systems or secondary functfons affected:

None.

E. Hethod of Discovery: P

The deviation regarding the electrical connection for the HSIV solenofdcontrol valves vas ldentlffed during the development of a correctivemaIntenance vork order to be used during the current Unit 2 refuelingoutage.

E

'ue to questions that vere identified during this vork order revlev theelectrical connection was reviewed and the physical equipment inspected.The as-found field connections were terminal blocks vlth. an electricalsurge suppressor between the terminals, all housed within a one and onequarter inch conduit connector {condulet).

The as-found condition was reported to PG&E management. PG&E engineeringreviewed the identified concern and determined that the files weredeficient ln that the surge suppressors were not addressed.

F. Operator Actions:

Upon notification by the PSRC „that the HSIV solenoid control valves wereinoperable the shift foreman'declared the HSIV's inoperable, declared anUnusual Event, performed the required.notifications, and directedoperations personnel to initiate an orderly shutdown of Unit l.

G. Safety System Responses:

None.

A. Imnedfate Cause:

EQ of the surge suppressors found between the HSIV solenoid control valveelectrical connections vas indeterminate, vhlch resulted fn two of four-HSIVs being declared inoperable.

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B. Root Cause:

The root cause of this event vas.personnel error, cognitive, by PGLEengineering personnel, in that the surge suppressor used within the MSIVsolenoid control valves electrical connections vas not addressed ln EQ

files.A contributory cause to this event vas an EQ review error in the September1981 environmental quallftcatton report to the HRC. This EQ reportincorrectly categorized the HSIV solenoid control valves as "SafetyRelated Electrical Equipment Outside Containment Which Hust Fall Properlyln a Severe Environment". This categorization assumed the de-energizedposition of the solenolds vould close the HSIVs, and based on thiscategortzatton, the failure of the surge suppressor would have beenacceptable.. A 1986 review identified that the solenolds vere required toenergize to close the HSIVs, and therefore must perform their safetyfunction ln a harsh environment as a result of postulated accidentscenarios. This revlev was incomplete ln that the solenoid valves werefound acceptable and the EQ file vas corrected, but the requtrement forthe surge suppressors EQ was overlooked.

An associated cause of this event was the failure to identify theinstalled configuration of the electrical connection duHng a 1987 EQ filereview as a result of discrepancy report (DR-87-14-E) regarding electricalconnections. That review concluded that the solenoid valves werequalified based on the.use of EQ splices.

Environmental considerations for terminal block connections outside ofcontainment vere first documented as acceptable ln PGIIE's EnvironmentalQualification Report, September 1981. Electrical connections outside ofcontainment were specifically addressed tn the EQ files for wire, whichindicated that "Terminal Blocks used for Class IE ctrcults outside ofcontainment are shielded from harsh environments by installation tn protectivecabinets." This evaluation vas based on PQkE experience, the low pressuresexpected outside the containment, and a review of the operationalrequirements. This evaluation concluded that NUREG-0588 (category II)requirements vere met.

However, this evaluation incorrectly identified the HSIV control solenotds as"Safety Related Electrical Equipment Outside Containment Which Must FallProperly In A Severe Environment" because the solenolds vere thought to closethe HSIVs when de-energized.

On March 3, 1984, and July 25, 1985, Units 1 and 2 respecti.vely entered Mode 3,for the first time.

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In 1986 a review of EQ files was performed as a result of discrepancy report(DR-86-14-3). This review properly identified the HSIV solenoid valves(SV-303, 304, 306 and 307) as the only Class I solenoids in a harsh environmentwhich were -required to be energized in order to fulfilltheir safety function(i.e. close the HSIVs). Terminal blocks were recognized as being acceptable inthis environment. However, the existence of the surge suppressors within theconnections was overlooked. The performance of the surge suppressors in theharsh environment created by a postulated HELB was indeterminate. Therefore,there was a potential for a short circuit of the surge suppressor, blowing thecontrol power fuse and precluding operator action to close the HSIVs forcertain scenarios. However, the probability of such an environment beinggenerated which would short the surge suppressor,'and preclude closure of theHSIVs, is very small. This is based on the following considerations:

l. A high energy line break must occur, and

2. The break must be on lead 3 or 4 in area GE or GH and0

3. The break must be downstream of the HSIVs or a reverse flow check valvemust fail, and

4. The break must be large enough to generate the harsh environment but smallenough not to actuate the protection system (approximately 0.6 square footfor a steam line break).

Based upon generic initiating event frequencies (reference HASH 1400) theprobability of this occurrence is less than 8.0 x 10-6 per reactoroperating year. This analysis assumes that the solenoids'urgesuppressor fails iamediately and no credit is taken for their locationinside a condulet which must be sufficiently heated to cause an electricalshort within the 10 minutes required for operator identification andaction to manually close the HSIVs. Further, fracture mechanics studieswould be expected to show that leakage would occur before a break. Thetemperature monitoring system in the GE-GH area would detect increasingtemperatures as a resu'lt of leakage, allowing time for appropriateoperator actions before a break would occur.

Based on the above considerations there were no significant safetyconsequences or implications as a result of this event.

An associated concern identified during investigation of this event wasthe lack of a specific EQ file for terminal blocks outside containment.The consideration of terminal block connections with regard to EQrequirements had been addressed in individual EQ files. However, thisdocumentation does not meet the current interpretation of 10CFR50.49requirements.

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V.

A. Iamediate Corrective Action:

VI.

The surge suppressors and terminal block electrical connection for thesubject solenoid valves were removed and replaced with EQ splices.

B. Corrective Action to Prevent Recurrence:

1. 'Nuclear Engineer1ng Nanual Procedure (NEHP) 3.13, "EnvironmentalQualification Review," will be revised to require specific.ident1fication of required terminat1ons in EQ files and coordinationof EQ file changes.

2. EQ files will be revised as. necessary to document terminationrequirements. Des1gn conf1guration will be verified to meet the filerequ1rements.

3. Responsible engineers will be further instructed regarding EQprocedures.

4. An EQ file for terminal blocks outside containment will beestablished, further documenting the1r acceptability.

A. Failed Components:

Hone.

B. Previous LERs on similar events:

Hone.

C. Associated 1tems requiring resolution:

During the investigation of this event PGhE discovered an error 1n thesubmittal to the NRC dated February 22, 1985, PGEE letter Ho. DCL-85-072,"Specif1c Comments to Relevant IE Bulletins and Informat1on Notices(Generic Letter 84-24)." Enclosure 2, Page 2 of 2, should have read:

84-47 —This notice concerned environmental testing of electricalterminal blocks. Safety c1rcuits in harsh environments 1nside containmentare provided with either LOCA-qualified splices or LOCA seal fittings atDiablo Canyon. Terminal blocks in safety circuits located outsideti i Mi idi i5 idi h i i iUJLMLJlld

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ISAAC SOIIU SOE>t04TI

(Underlined correction previously read ".")

|OPacific Gas and Electric Company 77 Beate Street

San Francisco, CA 94106

415I972 7000TWX910 372 6587

OJames 0 Shiffer

Vice PresidentNuclear Power Generation

December 9, 1988

PG&E Letter No. DCL-.88-299

U.S. Nuclear Regulatory CommissionATTN: Document Control DeskHashington, D.C. 20555

Re: Docket No. 50-275, OL-DPR-80Docket No. 50-323, OL-DPR-82Di.ablo Canyon Units 1 and 2Licensee Event Report 1-88-028-01

Entry Into Technical Specification 3.0.3 Hhen Two of Four MainSteam Isolation Valves Here Inoperable Due to InadequateEnvironmental Qualification of Electrical Connections

Gentlemen:

Pursuant to 10 CFR 50.73(a)(2)(i)(B); 50.73(a)(2)(ii)(B),50.73(a)(2)(v)(A and D) and 50.73(a)(2)(vii)(A and D), PGhE issubmitting the enclosed revision to Licensee Event Report 1-88-028,concerning an entry into Technical Specification 3.0.3 when two offour main steam isolation valves were inoperable due to inadequateenvironmental qualification of electrical connections. This

. revision is submitted to document the results of furtherinvestigation and identification of corrective actions to preventrecurrence.

This event has in no way affected the public's health and safety.

Kindly acknowledge receipt of this material on the enclosed copy ofthis letter and return it in the enclosed addressed envelope.

Sincerely,

. D. S i fer

cc: 3. B. MartinM. M. MendoncaP. P. NarbutB. NortonH. Rood

'.

H. VoglerCPUCDiablo DistributionINPO

Enclosure

DCl-88-EN-N008

2440S/0066K/DY/2190

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