IR 05000440/1987014

Augmented Investigation Team Insp Rept 50-440/87-14 on 870617-20.Major Areas Inspected:Initial Followup of Event, Scram Chronology,Msiv Control Design Description,Design Error,Preoperational Test Program,Lers & Assemblies

ML20236K468
Person / Time
Site:	Perry
Issue date:	07/21/1987
From:	Forney W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20236K444	List: IR 05000440/1987014 ML20236K441
References
50-440-87-14, NUDOCS 8708070126
Download: ML20236K468 (15)

Text

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, -1 U.S. NOCLEAR REGULATORY COMISSION l

Region III Augmented Investigation Team

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y Report No. 50-440/87014(DRP)- License NPF-58 Docket No. 50-440 Licensee: The Claveland Electric Illuminating Company )

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Post Office Box 5000 Cleveland, OH 44101 Facility Name: Perry Nuclear Power Plant, Unit 1 Inspection At: Perry Site, Perry, Ohio Inspection Conducted: June 17 through June 20, 1987 Inspectors: Kevin A. Connaughton DivisionofReactorProjects David E. Hills Division of Reactor Safety J. E. Mauck . l Nuclear Reactor Regulation-Gerald F. O'Dwyer DivisionofReactorProjects Michael E. Parker

• DivisionofReactorProjects Richard C. Knop, Team Leader DivisionofReactorProjects Approved By: e 7/a_,//7 ReactorProjects,Branc 1 Date /

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Table of Contents General Discussions Initial Followup of Event Scram Chronology AIT Formation Design Description - Main Steam Isolation Valve Control O_iscussion of Design Error Preoperational Test Program Review Procedure Preparation Procedure Test Results Followup on Previous Work Re-circulation Pump "B" Failure to Start Licensee Event Report Review - Potential Precursors Electrical Protection Assemblies Post Scram Evaluation Interim Administrative Controls for Responding to the Loss of a Single RP5 Llectrical Bus 10. Exit Interviews 11. Conclusions 12. Attachment - Commitment Letter Dated June 20, 1987 i

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. General Discussion Initial Follow-up of Event On June 17, 1987, the NRC was notified by the licensee of a reactor scras that occurred at 11:39 a.m. EDT that mornin As a result of the reactor trip and the unexplained closure and subsequent re-opening of the outboard main steam isolation valves (MSIVs), an inspector was dispatched to the site to review the circumstances of the event. The licensee had provided verbal assurances to Region III that the reactor would not be restarted pending review and approval by the NR Upon arriving on site, the inspector met with operations and engineering p'ersonnel to determine current plant status and review the licensee s initial determination of the cause of the event. The at the time and proceeding to plant was in Mode cold shutdow , licensee's The hot shutdown,tial ini determination was that the reactor scram was caused by the closure of the outboard MSIV The inspector reviewed the following documents and drawings to try to determine the cause of the MSIV closure:

• 10 CFR 50.72 Event Report

• Unit Logs

• Condition Report

• Final Safety Analysis Report

• Nuclear Steam Supply Shutoff System Power Distribution

• Reactor Protection System M-G Set 5001A ,

o Reactor Protection System H-G Set $001B e Nuclear Steam Supply Shutoff System Main Steam Line Isolation Valves - Inboard

• Nuclear Steam Supply Shutoff System Main Steam Line Isolation Valves - Outboard

• Nuclear Steam Supply Shutoff System Logic, Logic A and C

• Nuclear Steam Supply Shutoff System Logic, Logic B and D After reviewing these documents and drawings with the licensee it was evident that the closure of the outboard MSIVs was due to the loss of Reactor Protection System (RPS) Bus "A". Each MISV has two ( _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _

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. solenoid-operated pilot valves. The MSIVs are designed to fail closed upon loss of power to the pilot solenoids. Perry's current as-built condition has both ilot solenoid valves for the outboard MSIVs powered from RPS. Bus A."p" Therefore, upon loss of RPS Bus "A",

tht outboard MSIVs closed, resulting in the reactor scra At the time of the review the licensee had already conducted testing of the power supply to the outboard MSIV pilot solenoids and verified the configuration identified on as-built drawings was correc Review of the power su1 ply for the inbo:rd MSIV pilot solenoids identified that both t1e A and B solenoids for all four inboard MSIVs were powered from RPS Bus "B". This was. subsequently verified by the inspector to simulate loss ofon June RPS Bus18,"B".1987, This during the performance test verified of a test that all power was lost to both the A and B pilot-operated solenoid valves for the inboard MSIV Initial review of the Final Safety Analysis Report (FSAR) identified that Section 6.2. states, "Each main steam isolation valve is served bytwoindependentgilotvalves,eachofwhichispoweredfroman independent sourc Contrary to the requirements stated in the FSAR, the inboard and outboard MSIV pilot solenoids are not powered from independent sources, Scram Chronology Time Event Description 1100 Recirc pumps shifted to slow speed per startup procedure to enter natural circulation tes Tripped recirc pumps A and B per startup procedur RPS Bus A de-energizes when EPA breaker trip The following occur:

• Outboard MSIV pilot valves de-energize, MSIVs clos * Reactor scram due to MSIV closur * IRM, Div 1, SRMs, Div 1 - lose powe ,

• B0Pisolation(outboard) signa * RWCU/MSL drain outboard isolatio Transferred RPS Bus A to alternate suppl Outboard MSIVs opene _ _ - _ _ _ _ _ - _ _ _ _ _ _ - _ _ _ _

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1143 Operator closes outboard MSIVs with manual switc : Reset Reactor scra Reset tripped EPA, transferred RPS Bus A back to normal l power supply; reset half RPS tri Commenced 80P l isolation recover <

1156 Opened main condenser vacuum breakers due to;1ack of

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steam suppl Commenced cycling SRVs to control Reactor pressur Inboard MSIVs close on low vacuum signa Received reactor low level 3 scram due to void collapse and shrinkag Reset RPS scram signa l

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Legend i RPS - Reactor Protection System EPA - Electrical Protection Assembly MSIV - Main Steam Isolation Valve IRM - Intermediate Range Monitor SRM - Source Range Monitor B0P - Balance of Plant RWCU - Reactor Water Cleanup Systra MSL - Main Steam Line SRV - Safety Relief Valve AIT Formation Based on the unexpected closure of the MSIV Valves on loss of a single RPS bus trip, an Augmented Investigation team was formed and dispatched to the site on June 18, 198 An entrance meeting was held on June 19, 198 The charter of the team was to perform a fact-finding review of the events, to communicate these facts to regional and headquarters personnel, to identify 'any potential generic safety concerns, and to document the results of the onsite revie _

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Design Descr'iption: Main St'eam-Isolation Valve Control Each steam line has two containment isolation valves, one inside and one outside the containment barrier. The isolation valves are spring loaded, pneumatic piston-operated globe valves - designed to fail closed on loss of pneumatic pressure or loss of power to the power solenoids. Each valve has an air accumulator to assist in the closure of the valve upon loss of the air supply or electrical power to the pilot solenoids and failure of ,

the loaded spring. Each MSIV has'two control solenoids, "A" and "B", both i of which must be de-energized for the valve to close. During normal operation, both solenoids are energized. The "A" solenoid should be powered from RPS bus "A" (Distribution Panel P001), and the "B" solenoid from RPS bus "B" (Distribution Panel P002). - Power is provided to the  !

solenoids via MSIV control switch contacts; thus, each MSIV control switch contact section contains wiring associated with both RPS buses

"A" and "B". There is no physical separation provided between these circuit In fact, all wiring associated with a given control switch is color coded either yellow i orblue(iftheMSIVisa[ Division 2/ inboard" valve).if There is nothecolorMSIV is a distinction made between circuitry associated with redundant RPS buses in  !

this applicatio l Discussion of Design Error l The anomaly regarding the power to the MSIV pilot solenoid valves l originated wita General Electric drawing "GE828E445CA" dated May 12, 197 This drawing depicted both solenoids of the outboard MSIVs powered from i RPS A (C71-P001) and both solenoids of the inboard MSIVs powered from RPS B(C71-P002). However, Revision 2 dated February 14, 1977, provided for independent power sources to'each solenoid of a MSIV (RPS A power to solenoid A and RPS B power to solenoid B). This change was made by General Electric to prevent loss of a single RPS bus causing the the June 17, 1987 event at closure of the outboard or inboard (Gilbert MSIV Assoc (e.g.,iates Incorporated) for the

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Perry). The Architect Engineer Perry Plant failed to correctly transpose the power supply revision provided in GE 828E445CA, Revision 2, to the Gilbert Associates Incorporated (GAI) elementary diagram B-208-013 (sheet number 5). This error was carried throughout the later revisions and as a result non-independent rovided to the dual solenoids at the MSIVs. By letter power dated supplies June 20, 1987were p(attached) the licensee committed to modify the pow ,

supplies to the MSIV pilot solenoids. This modification will preclude an MSIV isolation caused by the loss of a single RPS power supply and will follow the design guidelines provided by General Electric and the designs l at other BWR 6 plants (e.g., Grand Gulf, River Bend presently instai ed andClinton). Ii addition, the modified design will be in agreement wi the Perry FSAR, Sections 6.2.4.2.1, 8.3.1.1.5.4, andFigure7.3-3(Sheet 4).

This modification will be completed prior to startup following a July 12, 1987 outag Furthermore, the licensee has committed to discuss the details of this modification with the NRC staf The staff was concerned that other trans)osing errors could have been made by GAI during the transposing process. 3y letter dated June 20, 1987, CEI is

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committed to complete a consistency review of General Electric drawings versus GAI drawings for the C71 (Reactor Protection), CSI (Neutron 1 Monitoring), and B21H (Nuclear Steam Supply Shutoff) systems. This review l was to be completed by June 22, 1987, and all attendant changes to the i drawings to be completed by June 26, 1987. A summary of the results of )q this review will be sent to the NRC. On June 20, 1987, approximately half of the system drawings had been reviewed with no apparent errors '

discovered. However, discrepancies were noted in such areas as footnote numbering, contact status representation and a relay designation. The relay designation was picked up in late 1986 and as a result DCP-86-P216 was issued on December 23, 1986, that will correct the applicable GAI drawings. The other discrepancies were considered to be correctly transposed in that they were done according to GAI footnote and contact representation philosophy. Based on the review of the interim results and the commitments provided by CEI, the staff concludes that this concern is resolve !

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During our revu v of the MSIV pilot solenoid power configuration the staff noted and tt.at with1n separation was not panels H13-P691, provide Speci 692,fically, the isolation concern was693, a divisional contact to :ontact isolation at relay K7A,B,C, This concern will be resolved when the power supply configuration for the MSIV solenoids is modified. At that time the divisional isolation will become coil to l contact which is acceptable. The contact to contact divisional isolation .

will be removed because the power su) ply for all of the B solenoids will l become RPS B power which is within tie same division as logic contacts 78 and 7D. The reverse is true for all of the A solenoid The separation concera involved intruder divisional wiring in panels H13-P691, 692, 693, .

and 694. This wiring was placed-in conduits that were not terminated as  !

close as practicable to the common device (K7A-D relays). As a result of  !

this incorrect termination, the intruder divisional wiring is physically touching the predominate panel divisional wiring which does not follow the guidelines of Regulatory Guide 1.75 or the commitments provided in the Perry FSAR Chapter 7 and In the June 20 letter, the licensee has committed to install a permanent barrier between the intruder divisional wiring and the predominate panel divisional wiring prior to startup following the July 12, 1987 outage. The staff finds this commitment acceptable and, therefore, the separation concern will be resolve . Preoperational Test Program Review Procedure Preparation j

The inspector reviewed the as-built drawing verifications to

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ascertain whether this process should have identified the design error. Since the actual plant configuration matched the plant electrical schematics and wiring diagrams the inspector concluded that this process would not have identified the problem.

f A review of Preoperational Test Procedure IC71-P002 by the inspector indicated that Section 6.3 had not been written in accordance with

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plant design drawings, but coincided with the system description given in the FSAR.

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It should be noted that as a result of earlier NRC identified violations in the Preoperational Test Program, various supplemental pragrams includin AssuranceReview,gSpecialProjectPlan1102,"TestProcedurehad bee Activities associated with these programs should have been sufficient to identify the conflicts between the system design depicted in the Final Safety Analysis Report (FSAR) and the as-built design which should have been tested in the preoperational test procedur The inspector's review of the Management Procedure Review Team (PPRT)

documentation indicated that the review did identify that the preoperational procedure did not reference all applicable drawings, but did not identify that the FSAR and the applicable drawings did not matc The MPRT accepted the response from the precaeration writer that the applicable drawings were identified in the initial checkout and run-in (IC&R) procedure. It should be noted that the IC&R procedure tested the MSIV circuitry in accordance with the drawings and not in accordance with the FSAR description. The MPRT failed to identify this fact as wel In summary, the reoperation test as written matched the FSAR description, but did not match the as-built condition of the plan The review process did not identify this discrepanc b. Procedure Test Results The inspector further reviewed Test Procedure 1C71-P002 results package documentation to determine why actual test performance did not identify any problems. Since the preoperational test procedure did not reflect the as-built design it should have been impossible to perform as written. However, the inspector noted that the System Test Engineer (STE) had in fact signed off the applicable steps as satisfactorily completed. Furthermore, these steps were Quality Assurance witness points and thus had also been verified by a Perry Plant Quality Assurance (QA) Inspector. These individuals are no lonoer employed at the Perry Plant. However, the licensee provided

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the NRC inspector with documentation of interviews they conducted I with the STE and QA Inspector following discovery of this problem.

! This documentation indicated that the STE had been confused in reoards

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I to the MSIV solenoid lights on Control Room panels H13-P622 and

{ H13-P62 Both the "A" and "B" solenoid lights for the outboard MSIVs are contained on panel H13-P623 while panel H13-P622 contains those for the inboard MSIVs. The STE had thought however, that the panel H13-P623 contained the lights for all the "A" solenoids while panel H13-P622 contained the lights for the "B" solenoids. Although these panels are now clearly labeled for each of these solenoid lights, the inspector verified through review of Field Deviation Disposition Request KL1-942 that they were not labeled as such at the time of the test. Furthermore, light suffice nomenclature appearing on the inside of the panels above each of the solenoid lights all contained an "A" in the number un panel H13-P623 and "B" on panel H13-P62 The STE

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did not realize that these numbers referred to the lights themselves instead of the solenoid designations. Thus, during testing when RPS MG Set "A" output breaker was opened causing the "A" arid "B" solenoid lights for the outboard MSIVs on panel H13-P623 to extinguish, the STE thought the "A" solenoid lights for both the inboard and outboard MSIVs had extinguished. He also verified that the solenoid lights on panel H13-P622 all remained energized. The inspector reviewed the Jumper and Lifted Lead Log for the time period of the test against electrical schematic and wiring diagrams to ensure that .

NuclearSteamSupplyShut-offSystem(NSSSS)logicinputrelayswould have remained energized upon loss of the RPS Bus. The inspector verified that jumpers installed would have kept panel H13-P622 MSIV solenoid lights energized under these conditions. This confirms what the STE and QA Inspector claim they sa In addition, a note in the chronological test log verifies they saw lights on only one panel extinguish. Thus, the STE mistakenly signed off the steps indicating that the "A" solenoids were off while the "B" solenoids were o The QA Inspector believed assurances from the STE that the lights i were correct. A similar explanation was provided by the licensee for the case of opening RPS MG Set "B" output breaker. However, 4 this explanation still ooes not address that the procedure steps specifically identify both "A" and "B" solenoids as being found on each of the panels. Therefore, these panel designations in the procedure steps would have had to have been ignored during the tes Actual conduct of the test failed to identify that the test procedure did not match the as-built design of the 11 ant. Accordingly, this process did not note discrepancies with t1e FSAR and thus process did not identify the plant design erro During the review of the Jumper and' Lifted Lead Log the inspector noted that the test procedure itself did not identify the jumpers l used to ensure the NSSSS logic input relays remained energized during the tes The jumpers were installed ard documented in the IC&R test on April 16, 1985. The IC&R tcsting was reviewed by the TPRC and the remainder of the test was released on April 24, 1985. Therefore, the jumpers were reviewed for future impact on subsequent preoperational testing in conjunction with the TPRC revie Furthermore, the IC&R test was included in the preoperational test results package and thus the jumpers were again available for TPRC review for impact on testing. The inspector has no further concerns regarding jumpers and lifted leads during the preoperational tes Followup on Previous Work As a result of the various errors in conjunction with the preoperational test, the remaining work performed by the involved individuals became suspect. Therefore, the licensee performed a review to determine the entire scope of the individuals' involvement in the preoperational test program. The STEs who improperly wrote or performed the test steps were both identified to have worked in

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f conjunctionwithonlyoneotherpreoperationaltestprocedur The results package for this procedure,1071-P001 "ReactorSrotection Systes," was then reviewed by the licensee to verify.that each step was written and perfomed to the appropriate drawings and that the test procedure addressed all testing commitments. Furthermore, the licensee verified that current surveillance instructions adequately address the logic originally demonstrated in the preoperational test. ThelicenseefoundthattheQAInspectorinvolvementwasa much wider extent. Various activities were undertaken by the licensee to develop an assessment of the QA Inspector's performance. Personnel records were reviewed to ensure adequate experience and qualification In addition, ten percent of the technical specification instrumentation i inspected by the QA Inspector during initial calibration was compared against subsequent surveillance tests to ensure adequacy of inspection results. Other testing witnessed by the QA Inspector was compared to Licensee Event Reports to confirm that his work did not contribute to significant safety deficiencies. Inspection reports were reviewed to ascertain his knowledge of system configuration and instrument acceptability. Finally, nonconformance reports by the QA Inspector were reviewed for adequacy of technical content and quality assessmen The licensee concluded through these various reviews that' remaining work by _these individuals does not constitute any significant proble In summary, the Preoperational Test Program should have been able to identify the discrepancy between the as-built design and the FSA This then should have led to discovery of the design error. However, due to an inadequate pre-operational test procedure, and the subsequent inadequate performance and quality assurance witnessing of this test procedure the discrepancy was not identified. Extensive reviews required by Special Project Plan 1102 failed to identify the testing problems. As a result, the licensee has completed a review to ensure remaining work by the involved individuals does not represent any serious concer . Recirculation Pump "B" Failure to Start l

The inspector interviewed maintuance personnel who had been involved with I troubleshooting and reviewed plant electrical schematic diagrams to j ascertain the cause of Recirculation Pump "B" failure to star Maintenance personnel had determined that diode D2B in Low Frequency Motor Generator Set Panel 1833-P001B, located in the Auxiliary Building, had sheared in half. The sheared diode acted like an electrical short causing current to bypass the K1338 starting sequence auto transfer relay. Failure l

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of this relay to energize, in turn, caused a Pump Motor Breaker 58 failure to close. This diode normally acts as a surge suppressor in the pump start

. circuitry. Upon removal of this diode the pump started satisfactoril It could not

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The diode was subsequently replaced by maintenance personne be positively determined what caused the diode to shear. The licensee ,

! indicated that this failure had not occurred at the Perry Plant in the l past and thus the inspector concluded that this was an isolated occurrenc l The inspector also verified that relay K133B is no longer energized once l the pump is started. Thus, failure of the diode will have no effect upon

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the pump while it is running. The inspector also verified this for relay K113B which is in parallel to relay K133B and diode D28. The inspector has no other concerns in this are . J.icenseeEventReportReview-PotentialPrecursors Review of Perry Licensee Event Reports (LERs) identified four LERs and six instances in which the loss of an RPS Bus has occurred previous to this even The LERs are:

• LER 86-044 August 6, 1986, Loss of RPS Bus "A" as a result of a failed capacitor in the EPA process control boar * LER 86-050 August 20, 1986, Loss of RPS Bus "B" as a result of inadvertent de-energization of RPS Bus B normal power suppl * LER 86-071 October 24, 1986, Transfer of RPS Bus "A" power supply resulting in unexpected B0P isolation * LER 86-072 October 25, 28, and 29, 1986, Loss of RPS Bus "A" as a result of voltage fluctuations while on the alternate power suppl A review of these LERs was performed to determine if any of the six events were precursors that should have alerted the licensee to the current design of the MSIV pilot solenoid valve power suppl This review consisted of determining the plant status, and specifically the position of the MSIVs at the time of each event to determine 'if any of these events were repeat occurrences of the June 17, 1987 event. This consisted of reviewing the applicable LERs, Unit Logs, and Test Procedure Based on the information reviewed and personnel interviews the inspectors came to the conclusion that during each of the previous events the reactor was in either cold shutdown or hot shutdown and the MSIVs were closed. As such, the licensee was not specifically cierted to the loss of power to the MSIV pilot solenoid valves for either the inboard or outboard MSIV The inspectors have requested the licensee review each of the specific instances identified in the above LERs to determim what information was available to the operators, and if this condition could have been recognized as a result of that inform 6 tio Further review of LER 86-044 dated August 29, 1986, identified that the licensee committed to change out all EPA electronic process control boards for both RPS Bus A and B Motor-Generator sets and their alternate power supplies. Review of the commitment tracking system and work orders indicates that to date the licensee has only changed out the EPA control boards for the alternate power supplie _- _ _ _ _ _ _ _ . _ _ - _ _ _ _ _ _ _ _ _

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As a result of the EPA trip' on June 17, 1987, the licensee has changed out the RPS Bus "A EPA circuit boards for the normal power supply and performed surveillance testing to verify conformance to Technical Specifications. This testing was witnessed by the inspector LER 86-044 also identifies that as a result of the capacitor failures in the circuit board the licensee determined that the manufacture has assigned a three year de-energized storage shelf lif During re)lacement of the circuit boards for RPS Bus "A" the inspectors o) served that the circuit board had a shelf life expiration date of December 25, 1991. This shelf life exceeds the three years identified in the LER. The licensee was able to provide adequate documentation t.o substantiate the extended shelf life and assure the inspector that this evaluation was per their established shelf-life program and conforms to applicable military standard The inspectors have expressed concern to the licensee that they are expected to comply with any commitments in the LER or provide a revision to the LER to clarify or modify any subsequent change '

7. Electrical Protection Assemblies i i The initiating device for the reactor scMm of June 17, 1987, has been determined to be a tripped Electrical Fratection Assembly (EPA) breaker in the RPS Bus "A". This device is a General Electric circuit breaker which provides undervoltage, overvoltage, and underfrequency protectio Two EPA breakers are provided in series for both the normal and backup RPS power supplies for both RPS Bus "A" and RPS Bus "B". The EPA breaker that tripped was 1C715003C which is second in series between the RPS M-G set "A" and the distribution pane Reactor operators initially transferre;l the RPS Bus "A" to the alternate power supply after the reactor scram and reset the reactor scram. A short time later the reactor operators reset the tripped EPA breaker and transferred power supply back to the normal RPS supply. The EPA breaker 5003C subsequently performed satisfactorily while in servic On June 18, 1987, the licensee performed surveillance instruction SVI-C71-T5230 to determine the as-found settings of the RPS "A" normal power supply EPA breakers, and found it necessary to perform breaker adjustments to bring the settings into specification to comply with Technical Specification requirement On June 19, 1987, the inspector witnessed the testing of the replacement logic card for EPA 1C71-S003A by Surveillance Instruction (SVI)-C71-T5230, Revision 2, " Reactor Protection Syatem (RPS)--Electrical Power Monitoring Calibration / Functional for IC71-5003A and IC71-5003C." The card failed the SVI and was replaced with a new logic card. Subsequently, both EPAs IC71-S003A and IC71-S003C (with a new logic card in each) passed SVI-C71-T5230. These boards were initially quarantined by the NRC pending evaluation of their failure mechanis _ J

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After a visual inspection and review of the licensee's testing of the boards the NRC released the quarantine. The circuit boards are to be sent determine to the the manufacturer,ilure specific fa mechanism. General Electric, The licensee has for further testing committed to to provide additional information into the failure mechanism upon completion of this testin On June 20, 1987, the inspector witnessed the successful retesting of EPA by SVI-C71-5232, 1C71-S003B,/

Calibration Functional for IC71-S003B and 1C71-S003D." Revision 2, "RPS--Ele Subsec uentig," EPA IC71-S003D also passed SVI-C71-5232. All EPAs in the affectec RPS A power supply were replaced and retested satisfactorily and all EPAs in the unaffected RPS "B" power supply were retested satisfactorily. All testing witnessed was performed correctly and no violations or deviations were identifie . Post Scram Evaluation (93702)

On June 19 and 20, 1987, the inspectors reviewed the licensee's post scram evaluation documented in the Post Scram Restart Report 1-87-9 dated June 18, 198 The report provided a listing of key, plant parameters along with their values prior to the scram, maximum and minimum values during the transient, and post scram stable value Additionally, the report included a chronology of events and an evaluation of plant response developed from the Sequence-of-Events recorder (SER), written statemerits oy on-shift operating personnel, Emergency Response Information System (ERIS) archived data, and the control room log. The.se information sources were attached to the repor The licensee's evaluation of the event was determined to be complete and consistent with the findings of the AIT relative to plant response and the identification of items requiring further evaluation and/or remedial action prior to plant restart. Specifically, the following items were identified; The tripping of the "A" RPS Equipment protection assembly which initiated toe even The discrepancy between the FSAR and the as-built MSIV pilot solenoid power supply wiring configuration The failure of the "B" reactor recirculation pump to manually start during scram recover The 100 degree / hour limit on reactor coolant system (RCS)

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cooldown rate was exceeded at the bottom reactor vessel head drain in the first hour following the scram.

l l The resolutions of items a. and b. above are discussed in Paragraphs 7  !

and 3 of this report, respectivel Regarding item c., the licensee determined that a diode in the reactor recirculation pump start circuitry had failed. The diode was  ;

replaced and the aump satisfactorily retested prior to plant restart on l June 22, 1987. T1is is further discussed in Paragraph !

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Regarding ites d.,'on June 18,.1987, the licensee performed an engineering evaluation of the RCS cooldown rate exceedence as required by L

Perry Technical Specification 3.4.6.1. The evaluation concluded that the cooldown rate of 130 degrees / hour experienced following the scram had no impact on fatigue or brittle fracture consideration The cooldown transient was determined to be bounded by existing analyses for control red drive mechanisms which are designed for up to 309 cycles with a cooldown rate of 200 degrees / hour. The inspector reviewed the engineering evaluation which was documented via Facility Change Request (FCR) No. 07036 and found it to be acceptabl . Interim Administrative Controls for Responding to the Loss of a Single

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RPS Electrical Bus On June 21, 1987, the inspector reviewed changes to System Operating Instruction (50I)-C71, "R)$ Power Supply Distribution (Unit 1)'" and Off Normal Instructier, (ONI)-071-2, " Loss of One RPS Bus (Unit 1) which were issued by the licensee between June 19 and 21,1987. The procedure changes were issued to reflect the as-built MSIV solenoid power supply wiring configuration including plant response to the de-energization of a single RPS electrical bus. Additionally, the inspector verified by direct observation that an information tag had been placed on the RPS power supply transfer switch which instructed operators not to use the switch unless the MSIV control switches have been verified /placed in the closed position. This instruction was provided to preclude inadvertent reopening of the MSIVs upon RPS bus re-energizatio . Exit Interviews The AIT met with the licensee representatives several times durino the inspection and at the conclusion of the inspection on June 20,198 The AIT summarized the scope and results of the inspection. The AIT leader stated that after discussions with Regional and NRR management, the plant would be allowed to restart based on:

a The NRC's review of the 10 CFR 50.59 analysis by the licensee indicating that there was no unreviewed safety questio A commitment by the licensee to accomplish certain task These ,

commitments are documented in the attached June 20, 1987 mem '

1 Conclusions The AIT's conclusions of the circumstances surrounding the unplanned closure of the MSIVs following loss of a Single RPS bus are as follows: ;

' The design error occurred in 1977 when GAI did not pick up on a design change to power each of the redundant solenoids from separate RPS busses. (Note subsequent review by CEI did not identify any .

other errors in RPS circuitry.)  !

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b. The wiring error was not identified durihg preoperational testing

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due to a series of errors involving the Procedure Writer, the System

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j Test Engineer, the Management Procedure Review Teas, and the Quality .

Assurance Engineer. Other work performed by the personnel involved was reviewed in dctail: No other significant problems were identifie c. The licensee intends to modify the circuitry during a July 12, 1987 7. L outage. In the interim, a review of 10 CFR 50.59 evaluation . .

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indicates that there is no unreviewed safety questio g _

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