IR 05000528/1998014

Revised Insp Repts 50-528/98-14,50-529/98-14 & 50-530/98-14 on 980526-0721.Violations Noted.Major Areas Inspected:Review of Safety & Regulatory Implications of Excessive Hpsip Discharge Check Valve Reverse Leakage for Units 1 & 2

ML17313A828
Person / Time
Site:	Palo Verde
Issue date:	03/03/1999
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML17313A827	List: IR 05000528/1998014 ML17313A826
References
50-528-98-14, 50-529-98-14, 50-530-98-14, NUDOCS 9903090133
Download: ML17313A828 (65)

Text

ENCLO URE U.S. NUCLEAR REGULATORYCOMMISSION

REGION IV

Docket Nos.:

License Nos.:,

Report No.:

Licensee:

Facility:

Location:

Dates:

Inspectors:

Approved By:

50-528; 50-529; 50-530 NPFP1; NPF-51; NPF-74 50-528/98-14; 50-529/98-1 4; 50-530/98-14 Arizona Public Ser vice Company Palo Verde Nuclear Generating Station, Units 1,2, and 3 5951 S. Wintersburg Road Tonopah, Arizona May 26 through July 21, 1998

.R. Bywater, Reactor Inspector, Engineering Branch N. Salgado, Resident Inspector Thomas F. Stetka, Acting Chief, Engineering Branch Division of Reactor Safety ATTACHMENTS:

Attachment 1:

Supplemental Information Attachment 2:.

Simplified HPSI Flow Diagram

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Attachment 3:

Degraded HPSI Flow Profile 9903090i33 990303 PDR ADQCK 05000528

PDR

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-2-EXECUTlVE SUMMARY Palo Verde Nuclear Generating Station, Units 1, 2, and 3 NRC inspection Report 50-528/98-14; 50-529/98-14; 50-530/98-14 This special inspection was conducted to review the safety and regulatory'implications of excessive high-pressure safety injection pump discharge check valve reverse leakage for Units 1 and 2. The licensee identified and reported these conditions to the NRC in accordance with 10 CFR Part 50.72 on May 14 and 15, 1998. The onsite portion of the inspection was conducted during the weeks of May 25 and June 8, 1998. Additional in-office inspection was conducted through July 21, 1998. The inspection also assessed the licensee's evaluation of the degraded conditions.

~Osrations

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Two examples of an apparent violation of Technical Specification 3.5.2 were identified for inoperability of the Unit 1 Train "B" high-pressure safety injection flowpath for approximately 6 years and the Unit 2 Train "A"high-pressure safety injection flowpath for approximately 5 years (Sections E1.1.b.2 and E1.1.b.4).

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Two examples of an apparent violation of Technical Specification 6.8.1 were identified for inadequate logkeeping practices. Abnormal conditions were not recorded in the Unit 2 control room logs when an unexpected safety injection tank level decrease occurred on October 10 and 28, 1997 (Section E1.1.b.1):

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Two examples of an apparent violation of 10 CFR Part 50, Appendix B, Criterion XVI,were identified for not identifying and correcting excessive reverse flowthrough Valve 2PSIB-V405 following two Unit 2 safety injection tank level decrease events on October 10 and 28, 1997 (Section E1.1.b.1).

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Units 1 and 2 log entries on May 13 and 14, respectively, did not address operability of the opposite-train high-pressure safety injection flow path when operability of Valves 1 PSIA-V404 and 2PSIB-V405 was in question (Section 01.1).

Two examples'f an apparent violation of Technical Specification 3.0.3 were identified for performing online maintenance on the Unit 1 Train "A"and Unit 2 Train "B" high-pressure safety injection systems without isolation from the opposite train, in excess of 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />, while the associated high-pressure safety injection pump discharge check valves were inoperable (Section E1.2).

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The licensee's investigation report was objective and provided a candid self-assessment of its performance; however, it did not evaluate inspector-identified issues in the areas of operations or online maintenance (Section E8.1).

Maintenance

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Athird example of an apparent violation of 10 CFR Part 50, Appendix 8, Criterion XVI,was identified. On April'9, 1998, the licensee missed an opportunity to correct the inoperable condition of Valve 1 PSIA-V404 when a personnel error was made during maintenance, resulting in the valve being reassembled incorrectly and the excessive reverse leakage not being corrected (Section E1.1.b.2).

En ineerin

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Afourth and fifthexample of an apparent violation of 10 CFR Part 50, Appendix B, Criterion XVI, were identified for inadequate corrective actions in the development of maintenance and testing procedures following operating experience assessments of NRC Information Notices 88-70 and 892 (Section E1.4).

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Event S no sis-4-Re ort Details This event involved excessive reverse flowthrough high-pressure safety injection (HPSI) pump discharge check valves in Units 1 and 2 caused by the incorrect assembly of the check valves. The incorrect assembly of the check valves could have'revented the valves from properly seating during reverse flowconditions. Therefore, the reverse leakage caused by the improper seating valve, would have'aused reduced HPSI injection flow.

I A simplified diagram of the HPSI system is depicted in Attachment 2. The HPSI system for each unit is comprised of two trains, "A and 'B,'nd each train has a pump, which takes suction from either the refueling water tank (RWT) or the containment recirculation sump. The discharge of each pump passes through a check valve, designated xPSIA-V404 for the Train 'A" valve (where.'x's the unit designator) and xPSIB-V405 for the Train "B" valve. The discharge from each pump is then separated into four cold-leg injection lines, one for each of the cold legs of the reactor coolant system (RCS), and a hot-leg injection line. Each cold-leg injection line contains a motor-operated valve and the flowpath is combined with the opposite HPSI train to form a single flowpath. Upon a safety injection actuation signal, the HPSI trains are cross connected via the cold-leg injection lines.

If a HPSI pump is not operating and the motor-operated valves for both trains are open, the HPSI pump discharge check valve for the idle pump provides isolation from the operating train. This prevents diversion of HPSI flowfrom the RCS to ensure that an adequate amount of flow is provided or emergency core cooling during a loss-of-coolant accident (LOCA).

A check valve that was improperly assembled could affect the leakage through the valve during reverse flowconditions. For example, referring to the simplified flowdiagram in Attachment 2, if the

"B" HPSI pump discharge check valve SIB-V405 were to fail to close completely under reverse flow conditions, and the "B" HPSI pump was-IaepembIenot runnin with the in'ection valves o en', part of the injection flowfrom the "A" HPSI pump would be directed back through HPSI Valves SIA-UV617,-

627, -637, -647 and SIB-UV616, -626, -636, -646. The flowwould then be directed through the "B" HPSI pump mini-flowline Valves SIB-UV667 and SIB-659, and back to the RWT. As stated previously, upon a safety injection actuation signal, the cold-leg injection valves would open and remain open.

The HPSI pump discharge check valves are 4-inch, 1500-pound, bonnet-hung, pressure-seal swing check valves manufactured by Borg-Warner. On April 9, 1998, during a Unit 1 refueling outage surveillance test, Valve 1 PSIA-V404, the Unit 1, Train "A" HPSI pump discharge check valve, failed to meet its acceptance criterion for reverse flowduring a flowtest. The cause of the condition was determined to have been vertical misalignment of the valve disc within the valve body, which caused the disc to become ja~~d-cocked'nd not seat properly. On May 7, 1998, the licensee concluded that the amount of leakage resulted in a condition outside the design basis of the facility.

Valve 1 PSIA-V404 was repaired during the Unit 1 refueling outage and its post-maintenance test was completed satisfactorily. However, on May 13, 1998, with Unit 1 operating, the check valve system engineer determined that the valve had been repaired incorrectly. Additional

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-5-esting confirmed that the valve was inoperable because of excessive r'everse leakage. The licensee repaired the valve and returned the Unit 1 HPSI system to an operable condition on May 15, 1998.

During its review of the applicability of the vertical misalignment issue to other HPSI pump discharge check valves, the licensee performed non-intrusive measurements of valve dimensions and reviewed

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2PSIB-V405, the Unit 2, Train "B" HPSI pump discharge check valve was also misaligned and testing confirmed that the valve had excessive reverse flow. The licensee repaired-reworked'he valve and (

returned the Unit 2 HPSI system to an operable condition on May 16, 1998. On June 5, 1998, they reported the condition to the NRC in Licensee Event Report (LER) 50-528/-529/-530/98-006.

The reverse leakage conditions were masked prior to April 9, 1998, due to an inadequate surveillance test. Specifically, the surveillance test in use only measured the injection flow rate to the reactor vessel under limited conditions and did not quantify the reverse flowleakage through the check valves.

The NRC initiated this inspection to review the event, determine if the licensee had returned the HPSI systems to an operable condition, and assess the licensee's performance.

I 0 erations 01 Conduct Of Operations 01.1 Unit 1 and Unit 2 - Technical S ecification TS 3.0.3 Late Ent

The inspectors reviewed events and circumstances associated with the initial logging of a late entry into TS 3.0.3 for Unit 1 and Unit 2 when HPSI pump discharge check valves were inoperable because of excessive reverse flow leakage.

Observations and Findin s Unit 1 The Limiting Condition for Operation (LCO) for TS 3.5.2 requires that two emergency core cooling system (ECCS) subsystems shall be operable for each unit.with each subsystem comprised of an operable HPSI pump, an operable low-pressure safety injection (LPSI) pump, and an independent operable flowpath. If a HPSI pump discharge check valve allows excessive reverse flow, then the opposite-train ECCS subsystem does not contain an independent operable flowpath. When the HPSI systems are interconnected via the cold-leg injection valves, the check valve is the flowpath boundary. An action requirement associated with TS 3.5.2 allows one ECCS subsystem to be inoperable for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> prior to requiring the initiation of a plant shutdow chnical Specification 3.0.3 requires if an LCO is not met, except as allowed by the associated action requirement, that the licensee shall initiate action within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to place the unit in a mode in which the LCO is not applicable.

As documented in the Unit 1 log for May 13, 1998, at 3 a.m. the licensee began a planned Train 'A" equipment maintenance outage and declared Train "A"equipment, including the Train 'A'PSI system inoperable.

On May 13, 1998, at 1 p.oi., the licensee conducted a meeting to discuss operability of Valve 1 PSIA-V404, the Unit 1 Train "A" HPSI pump discharge check valve. The licensee had questioned whether the valve had been assembled correctly following maintenance during the April 1998 refueling outage. (For additional details, see Section E1.1.b.3). The licensee's reportability determination, dated May 21, 1998, documented that at this meeting, operations personnel concluded that sufficient evidence existed to suggest that the valve vreukh~ni ht'ot perform its intended function, and that the valve was declared inoperable, pending testing.

Following the 1 p.m. meeting, the Unit 1 operators made an entry in the Unit 1 log at 2:32 p.m. that HPSI Train,"A" was inoperable due to the potential that the internals for Valve 1 PSIA-V404 were misaligned (HPSI Train "A was already inoperable. This entry explicitly identified a new cause for the inoperable condition.) The entry also stated that operations would establish conditions necessary to test the valve for reverse flowand was proceeding with isolating the Train "A" HPSI system from the Train "B" HPSI system. The inspectors noted that the log entry did not address operability of the PSI Train "B"flowpath.

The operators completed the isolation of the HPSI trains at 3:45 p.m.,

I hour and 13 minutes after the 2:32 p.m. Iog entry. The licensee informed the inspectors that the isolation of the HPSI trains, by closing and removing power from the Train "A" HPSI loop injection valves, was performed to provide equipment isolation in preparation for testing and maintenance on Valve 1 PSIA-V404. The licensee further stated that the isolation was not initiated to separate the HPSI trains to prevent flowdiversion from the Train "B" HPSI system through the Train "A" HPSI pump discharge check valve during an accident. Since, as discussed in Section E1.2 of this report, the reverse flow leakage through the check valve would have" reduced the HPSI flowrequired to mitigate an accident condition, the inspectors considered that Train "B" did not have an independent operable flowpath. The Train "A" HPSI system was already inoperable for maintenance.

Consequently, this condition exceeded the LCO for TS 3.5.2, and therefore if o erations had known that the check valve would not erform its intended function" required an entry into TS 3.0.3.

Control room operators did not record the TS 3.0.3 entry in the Unit 1 log. The LER for this event, d

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dydittd when Valve 1 PSIA-V404 was declared inoperable,

~. During later discussions, the licensee informed the inspectors that operators recognized the flowdiversion potential and impact on system operability, but considered

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~otenttatt degraded condition until testing confirmed

~. The inspectors concluded that TS 3.0.3 should have been entered at 2:32 p.m. on May 13, when HPSI Train "A"was declared inoperable due to Valve 1 PSIP-Y404.~0 TS 3.0.3 required that within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, action shall be initiated to place the Unit in a mode in which TS 3.5.2 did not apply. The basis for T.S. 3.0.3 stated that the purpose of the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> was to allow for the preparation for an orderly'shutdown before initiating a change in plant operation and that this time permits the operator to coordinate the reduction in electrical generation with the load dispatcher to ensure the stability and availability of the electrical grid. Even though the control room operators recognized that the inoperable check valve had an impact on system operability, they did not initiate action to place the Unit in a mode in which the HPSI system was not required. When the inspectors discussed this issue with department management representatives, the inspectors determined that these managers were unfamiliar with the 1-hour requirements of TS 3.0.3. The managers informed the inspectors that they considered the I hour specified in TS 3.0.3 as an additional hour that was available to correct the inoperable condition instead of the time allowed to prepare for.an orderly plant shutdown.

At 3:45 p.m. on May 13, 1998, operators completed the isolation of all four Train "A" HPSI RCS injection valves (Valves SIA-HV-617, 627, 637, 647). Therefore, Train "B" of the HPSI system was

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made operable at that time. On May 16, 1998, operators ues ioned whether both trains of the HPSI system were inoperable on May 13, 1998, that-aaand made a conserva ive entry T330.~,

dd t dtt TS303 tgt tk I g I t IS. Td o eratorsinitiatedaCRDR 180317 tohavethe TS3.0.3ent evaluated."Theinspectorsverified that a late entry was made into the Unit 1 log. The inspectors considered that TS 3.0.3 was declared from 2:32 p.m. on May 13, 1998, when Valve 1 PSIA-V404 was inoperable, until the Train "B" HPSI system flowpath was made operable at 3:45 p.m. by isolating the two HPSI trains. Subsequent to the onsite portion of the inspection, the licensee changed its position with respect to the late entry into TS 3.0.3 and revised the logs accordingly.

'I The licensee's failure to comply with the requirements of TS 3.0.3 was determined to be an example of an apparent violation (50-528/-529/-530/9814-01).

Unit 2 On May 14, 1998, at 9:55 p.m., operations declared the Train "B" HPSI pump inoperable after receiving a memorandum from engineering (see Section E1.1.b.4) recommending that Valve 2PSIB-0403,tk T

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...~in a similar manner to the Unit 1 actions, operators isolated the HPSI trains in anticipation of performing testing and maintenanc'e on Valve 2PSIB'-V405. For this case, however, isolation of the Train "B" HPSI injection valves was completed within 1

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hour, at 10:35 p.m. On May 16, 1998, the Unit 2 log had a late entry documenting that at 9:55 p.m. on May 14, 1998, an entry into TS 3.0.3 was required due to the Train "A"HPSI system being inoperable due to Valve 2PSIB-V405 being suspected of having excessive back leakage. Another late entry on May 16 documented that at 10:35 p.m. on May 14, TS 3.0.3 was exited when the Train "B" HPSI injection valves were isolated. Subsequent to the onsite portion of the inspection, the licensee changed its position with respect to the late entry into TS 3.0.3 and revised the logs accordingly.

Operations personnel did not demonstrate an understanding of TS requirements nor an understanding of the impact of the misaligned HPSI check valve on system operability. An example of an apparent violation was identified forfailure to implement the requirements ofTS 3.0.3 for Unit 1.

Operations Procedures and Documentation 03.1 Res onse to Inade uate HPSI Flow Ins ection co e The inspectors reviewed existing procedures that the licensee would have used during LOCA scenarios involving inadequate HPSI fiow. The inspectors also interviewed reactor operators and observed two crews in the simulators respond to a LOCAwith degraded HPSI flow.

Observations and Findin s A senior reactor operator walked the inspectors through existing procedures that control room operators would be expected to use during a LOCAwith inadequate safety injection flow.

Emergency Procedures 40EP-9EO03, "Loss of Coolant Accident," Revision 5, and 40EP-9E009, "Functional Recovery," Revision 6, addressed the degraded HPSI flowcondition and the required actions to recover the inventory control safety function. The inspectors verified that the instrumentation available to the operators in the control room would allow for the diagnosis of a degraded HPSI flowcondition. IfHPSI flowwas unacceptable and unrestorable, the emergency procedures provided a method of alternate response to recovery. The inspectors also observed two crews successfully respond to a LOCAwith degraded HPSI flowscenario on the plant simulators. The circumstances of this simulator scenario, "LOCAwith Degraded HPSI Flow," July 14, 1998, were a LOCAand a failure of the Train "B" HPSI pump with its associated discharge check valve stuck at 15 percent open.

Operator performance was considered acceptable ifthe crew took action to depressurize the RCS to initiate LPSI injection flow prior to the reactor vessel outlet plenum level decreasing to less than 23 percent. The performance of both crews was goo Conclusions The inspectors concluded that existing procedures were adequate and available for responding to a degraded HPSI flowcondition.

II Maintenance Conduct of Maintenance Valve Maintenance Ins ection Sco e

The inspectors reviewed the maintenance history of the HPSI pump discharge check valves, interviewed maintenance and engineering personnel, reviewed maintenance procedures, and examined a spare valve in the maintenance shop.

Observations and Findin s Evolution of Maintenance Procedure The subject HPSI pump discharge check valves were 4-inch, 1500-pound, bonnet-hung, pressure-seal swing check valves manufactured by Borg-Warner. The licensee's maintenance procedures for these valves had evolved since plant construction. The original maintenance procedure applicable to the subject valves, OLM Manual 1024, Revision A, did not identify specific instructions regarding how far the bonnet retaining ring should be threaded into the body of the valve. The licensee informed the inspectors that during plant construction, valves were disassembled prior to being welded in place. During reassembly, the bonnet retaining ring was threaded into the valve body until it bottomed after the internals were installed.

As described to the industry in NRC Information Notice (IN) 89-62, "Malfunction of Borg-Warner Pressure Seal Bonnet Check Valves Caused By Vertical Misalignment of Disc," dated August 31, 1989, the assembly instructions for the subject valves were missing an essential assembly step, which, if not implemented, would result in=the disc assembly being suspended too low inside the body of the valve. If the disc assembly was suspended too low, the valve may initiallyseat acceptably but still become jammed after forward flowexercised the valve, thus preventing proper valve seating and subsequently allowing reverse flow leakage. The original factory assembly process included a step that unthreaded the bonnet retaining ring after it bottomed in the valve body until the correct disc height as viewed throu h the end of the uninstalled valve " was obtained. Backing out the retaining ring to achieve the correct vertical dimension was not included as a required step in the licensee's original procedure i.e. vendor instruction manual ".

-10-he licensee issued Procedure 31MT-9ZZ17, "Disassembly and Reassembly of Borg-Warner Check alves," Revision 0, on November 30, 1992, after receiving vendor information developed in response to IN 89-62. As discussed in Section E1.4, the licensee had initiallydetermined that no actions were necessary in response to the IN. This contrib'uted to the 3-year delay from the time that IN 89-62 was issued to the time that Procedure 31MT-9ZZ17 was issued.

As r commended b he vendor "tahe procedure included a step of measuring the distance from the top of the valve body to the top of the bonnet retaining ring (called the "A'imension) before valve disassembly and after reassembly.

However, this step did not ensure that the valve disc-to-body vertical alignment was correct. Ifthe valve had b0en previously disassembled, measuring the "A"dimension prior to maintenance and returning the valve to that 'A'imension during reassembly would have merely returned the valve to its previous configuration, which may have been incorrect.

The licensee issued Revision 1 of Procedure 31MT-9ZZ17 on November 17, 1994. This revision included measurement of the "B" dimension, the distance from the top of the valve bonnet to the top of the valve body. The procedure contained instructions to determine the correct vertical disc-to-body configuration, as determined by the disc-to-body measurements, and place the valve in the correct

. alignment. However, performing these steps was only required if inspection of the valve identified improper seating. An enhancement to the dimensional measurement process was implemented in Procedure 31MT-9ZZ17, Revision 4, on January 24, 1997, to simplify the measurement process. The

. licensee did not djust valve alignment when Nese-procedure revisions 4 were was made~. The 1994 revision of Procedure 31 MT-9ZZ17 appeared adequate to erisure that the correct valve alignment was established, hA-and correct vertical alignment of eII-ef-thethe Unit 2 and Unit3 V404 valves was-eethad been verified at that time and the other four HPSI check valves had cake e of 10 m or less".-.

Maintenance Histo With respect to Valve 1PSIA-V404, the Unit 1, Train "A" HPSI pump discharge check valve, when maintenance was performed on April 10, 1998, Procedure 31MT-9ZZ17 was not followed because of personnel error while taking measurements to establish the correct "A"and "B" dimensions. This resulted in the erroneous conclusion that the valve disc had been approximately 0.5 inches too high inside the body of the valve. To correct this condition, a 0.5-inch spacer ring was installed. Later, as discussed in Section E1.1.b.3, the licensee recognized this error and corrected the condition by removing the spacer on May 15, 1998. The previous time that Valve 1 PSIA-V404 was disassembled was May 1, 1992. The steps to measure the "A"or "Be dimensions and verify that the disc-to-body alignment was correct were not included in the maintenance procedure at that time. Therefore, the valve disc was susceptible to jarnrntrtg-~cockin 'pen since May 1, 1 992.

On May 15, 1998, the licensee discovered that the disc in Valve 2PSIB-V405, the Unit 2, Train "Bn HPSI pump discharge check valve was vertically misaligned. Valve 2PSIB-V405 was previously disassembled on April 14, 1993. The Unit 2 valve'was last reassembled prior to the revision of Procedure 31 MT-9ZZ17 that would have established the correct vertical alignment. Therefore, the valve disc was susceptible to jeremtrtg-~cockin 'pen since April 14, 199 For the remaining HPSI pump discharge check valves on all three units., the licensee evaluated the maintenance and testing history, performed as-found external measurements of the "A"and "B"dimensions, and performed reverse fiowtests. Each of the remaining four valves had as-found reverse flowtest results of 0 gpm.

onclusions The licensee's maintenance procedure for Borg-Warner bonnet-hung, pressure-seal check valves did not include adequate instructions for ensuring correct vertical disc alignment until November 1994. The inspectors concluded that the licensee missed an opportunity to identify and correct the vertical'alignment issue at that time. Once the problem was recognized in 1998, the licensee developed and implemented an acceptable plan to identify and correct the adverse condition on all of the HPSI pump discharge check valves.

Valve Testin Ins ection Sco e The inspectors reviewed the inservice testing (IST) history of the HPSI discharge check valves, interviewed maintenance and engineering personnel, and reviewed testing procedures.

bservations and Findin s The licensee identified in its OEA review of NRC IN 88-70, "Check Valve Inservice Testing Program Deficiencies," that its IST program did not require reverse-flow testing of the HPSI pump discharge check valves. As discussed in Section E1.4, the licensee originally concluded that because they had an NRC-approved IST program, any changes to the program were considered enhancements.

Therefore, the need for procedure revisions was not considered a priority. The licensee added reverse-flow testing requirements for these valves to its IST program on July 26, 1992. The test methodology involved operating one HPSI pump and verifying adequate fiowwas delivered to the RCS when both trains of the HPSI system were cross~nnected.

This method was intended to demonstrate that the HPSI pump discharge check valve in the idle train had closed as evidenced by maintaining sufficient flowto the RCS with inconsequential flowdiversion through the check valve. No explicit acceptance criterion was specified for reverse flowthrough the check valve. The test was performed for each valve during refueling outages to satisfy the IST program surveillance requirements of TS 4.0.5.

Due to the absence of reverse flow measurements through these check valves, these surveillance tests did not identify that Valves 1PSIA-V404 and 2PSIB-V405 were inoperable since 1992 and 1993, respectively.

This forward-flow testing methodology continued until the 1998 Unit 1 refueling outage. As discussed in Section E1.1, Procedure 73ST-9XI33, "HPSI Pump and Check Valve Full Flow Test," Revision 9, was issued on March 12, 1998, to perform a forward-flowtype test and included an allowable 20 gpm variance in the measured flow in the acceptance criterion. The development of an explicit acceptance criterion for check

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-12-alve reverse flowwas a corrective action from Condition Report/Disposition Request (CRDR) 2-7-0420 that was written following the October 28, 1997, Unit 2, safety injection tank (SIT) level decrease event described in Section E1.1.b.1. AfterValve 1PSIA-V404 failed this test on April 9, 1998, and was repaired, plant conditions had changed and precluded the forward-flowtype test from being performed. Therefore, the licensee issued Revision 10 of Procedure 73ST-9X133 on April 11, 1998, which included a new testing methodology consisting of pressurizing the downstream side of the check valve and monitoring reverse flowthrough the valve. The new methodology was subsequently described in a new procedure (Procedure 73ST-9XI35) issued on May 13, 1998.

Afterthe test failure of Valve 1PSIA-V404 during the Unit 1'efueling outage, engineering personnel continued investigation of the performance requirements for HPSI discharge check valve reverse flow. Based on engineering analysis of ECCS performance requirements and actual HPSI system performance (Section E1.2), the licensee determined that a reverse flowacceptance criterion of 10 gpm at a test differential pressure of 50-125 psid would be valid for all six valves in the three units.

Procedure 73ST-9XI35, "HPSI Pump Discharge Check Valve Closed Exercise Test," was revised to include the 10 gpm acceptance criterion in Revision 6 on May 26, 1998.

Technical Specification 4.0.5 states, in part, that, "... inservice testing ofASME Code Class 1, 2, and 3 pumps and valves shall be performed in accordance with Section XI of the ASME Boiler and

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Pressure Vessel Code and applicable Addenda... ~ "

Prior to January 15, 1998, the applicable Edition of the ASME Code was the 1980 Edition through

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Winter 1981 Addenda. Subsection IWV, "Inservice Testing ofValves in Nuclear Power Plants," of Section XI of the ASME Code, Article IWV-2000, defines Category Avalves as those forwhich seat leakage is limited to a specific maximum amount in the dosed position forfulfillmentof their function and defines Category C valves as those which are self-actuating in response to some system characteristic, such as check valves. Article IWV-2000 also states that valves within the scope of this section shall be placed in one or more categories and that when more 'than one distinguishing category characteristic is applicable, all requirements of each of the individual categories are applicable.

Effective January 15, 1998, the applicable Edition of the ASME Code was the 1989 Edition.

Subsection IWV, "Inservice Testing ofValves in Nuclear Power Plants," required that valve testing be performed in accordance with the requirements stated in ASME/ANSI Inservice Testing ofValves in Light-Water Reactor Power Plants OM-10, OMa-1988 Addenda to the OM-1987 Edition. The definitions and requirements identified above for the 1980 ASME Code Edition are equivalent to the 1989 ASME Code Edition.

The HPSI pump discharge check valves have a safety-related function to close to prevent diversion of flow between trains of a system. As identified in NUREG-1482, "Guidelines for Inservice Testing at.

Nuclear Power Plants," the ASME Code does not specifically require that these valves, be Category A; although, there may be a leakage limitbased on the total system requirements. The licensee conducts their IST program

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-13-in accordance with Procedure 73DP-9XI01, "Pump and Valve Inservice. Testing Program

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Component Tables," Revision 5. Procedure 73DP-9XI01 identified that the HPSI pump discharge check valves were classified as Category C valves. This classification was acce'ptable; however, NUREG-1482 also identified that for valves ofthis type that th'e licensee should evaluate the consequences of reverse flow. This evaluation should consider. 1) the loss ofwater from the system and connecting systems; 2) the effect that the leakage might have on components and piping downstream of the 'valve'nd 3) any increase in radiological

. exposure resulting from the leakage. The licensee had not performed evaluations of this type until the current problems with the HPSI pump discharge check valves were identified. These evaluations are discussed in Sections E1.1 and E1.2. At the conclusion of the onsite portion of the inspection, the licensee was evaluating whether the HPSI pump discharge check valves should be re-classified as Category A in the IST program.

onclusions The IST program was ineffective at demonstrating operability of the HPSI pump discharge check valves.

III En Ineerin Conduct of Engineering HP I

stem De raded ondition Review To review the HPSI system degraded condition, the inspectors toured relevant areas of the facilityincluding the auxiliary building, control room, and maintenance shop. The inspectors also conducted interviews with licensee personnel, reviewed selected procedures, calculations, maintenance packages, OEAs, and corrective action documents, and reviewed the licensee's investigation report and LER 50-528/-529/-530/98-006.

bservations and Findin s 1997 Unit 20uta es On October 28, 1997, during Unit 2 restoration prior to startup from a forced outage, operators were performing Procedure 40OP-9SI02, "Recovery from Shutdown Cooling to Normal Operating Lineup," Revision 14, Section 7.0, "Boration Of Cold Leg Injection Lines," using the Train "A"HPSI pump. During the evolution, pressure and water level in SIT 1A decreased unexpectedly when Valve SIB-UV638, the SIT 1,a, check valve leakage line isolation valve, was opened to establish a recirculation path for the 1A injection line. The reactor operator closed Valve SIB-UV638, which terminated the loss of inventory, and restored the SIT pressure. The onshift crew contacted engineering personnel, who determined the cause of the loss of inventory in SIT 1A was leakage past Valve 2PSIB-V405, the Train "B" HPSI pump discharge check valve, to the RW e engineering personnel reviewed the results of the previously performed reverse exercise test of Valve 2PSIB-V405, conducted during the previous refueling outage in accordance with Procedure 73ST-9X133, and identified that the check valve was found to have a leakrate.of approximately 30 gpm. This test had been performed to satisfy the IST program requirements. As stated previously in Section M1.2, the refueling outage test was accepted because adequate forward flowto the RCS was obtained when the HPSI trains were cross connected but there was no explicit acceptance criterion for reverse flowthrough the check valve. Therefore, the operators concluded that this amount of reverse flowdid not prevent the HPSI system from performing its design function and plant startup continued. The ondhift crew initiated CRDR 2-7-0420 to evaluate a procedure change to alert operators of the potential to affect SIT level when performing the cold-leg boration evolution.

The check valve leakage caused a depressurization of the loop injection piping during the cold-leg boration to approximately 600 psig and the SIT began to discharge as designed. The licensee documented in the CRDR that the condition could have been identified before if operations had questioned why safety injection header pressure did not respond as expected during the cold-leg recirculation line-up prior to opening SIB-UV638. The safety injection header pressure should have not decreased below SIT pressure and the SIT should not have discharged. The CRDR also documented that, "Operations noted the response to Pl-339 [safety injection header pressure] was not normal, however, they'were unable to explain the condition so the procedure was continued."

/

The CRDR also contained a reference to a similar event, which occurred on October 10, 1997,

'uring plant restoration prior to startup from the previous refueling outage. Again, SIT level

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ecreased during the performance of Procedure 40OP-9SI02, Section 7.0 with the Train "A" HPSI ump. In that particular instance, the decrease in level was terminated by the reactor operator closing the Train "B'njection valve and isolating the trains. This similar example was highlighted in the CRDR because the same crew was on duty when each SIT transient occurred during the cold-leg boration evolution. The crew did not request engineering assistance to evaluate the SIT level transient and the crew did not conclude that Valve 2PSIB-V405 was leaking. Reactor startup activities continued and the reactor was made critical later that day. With respect to the October 10, 1997, event, operations personnel had concluded that the unexpected loss of SIT inventory was caused by an "eductor effect," which caused a localized low pressure condition at the SIT outlet during HPSI cold-leg recirculation, and that the condition should have been expected. The inspectors did not consider this to be a plausible explanation because of the high localized pressure drop that would be required to decrease pressure below SIT pressu're.

The inspectors reviewed control room and Unit logs for October 10 and 28, 1997, and identified that no log entries were made regarding the SIT level decreases.

The licensee's Procedure 40DP-9OP22, "Operations Logkeeping," Revision 9, Step 3.3.5 stated, in part, "The information entered in the Control Room Log shall include... abnormal occurrences, unless previously logged and identified by an active corrective action document." The licensee did not+-agree with the inspectors'haracterization that the SIT level transients were abnormal occurrences. The inspectors determined that the

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-15-licensee's procedures did not exempt the conditions experienced on October 10 and 28 from being logged in accordance with the logkeeping procedure. Therefore, the inspectors concluded that the failure to log the abnormal SIT level transients that occurred on October 10 and 28, 1997, were two examples of an apparent violation ofTS 6.8.1, which required adherence to Procedure 40DP-9OP22 (50-528/-529/-530/9814-02).

While the licensee identified a check valve reverse leakage problem as documented in CRDR 2-7-0420 on October 28, 1997, they failed to take prompt corrective actions to resolve the problem. 10 CFR Part 50, Appendix B, Criterion XVI,"Corrective Action," requires that measures shall be established to assure that conditions adverse to quality are promptly identified and corrected and in the case of significant conditions adverse to quality that the measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition. The inspectors considered the October 10 and 28, 1997, Unit 2 SIT drain events to have been occurrences where; a significant condition adverse to quality (excessive reverse flowthrough Valve 2PSIB-V405) was not promptly identified and corrected.

These were considered the first two examples of an apparent violation of 10 CFR Part 50, Appendix B, Criterion XVI(50-528/-529/-530/9814-03).

, During the evaluation and resolution of CRDR 2-7-0420, the licensee concluded that a 20 gpm check valve reverse leak rate acceptance criterion should be sufficient to prevent unacceptable HPSI flowdiversion. This conclusion was not based upon a rigorous calculation of the impact of flowdiversion; rather, it was based on a review of leakage acceptance criteria for some check valves in the LPSI system and the methodology employed to select their.

leakage acceptance criteria. Procedure 73ST-9XI33 was changed in Revision 9 to include the explicit acceptance criteria of either. 1) less than 20 gpm difference between the sum of hot and cold-leg injection flowrates before and after the HPSI trains were cross connected; or 2)

hot-leg injection flowgreater than or equal to 525 gpm, cold-leg injection flowgreater than or equal to 525 gpm, and total HPSI flow less than or equal to 1200 gpm. The forward-flow acceptance criteria were consistent with the surveillance requirements in TS 4.5.2.h.

onclusions The inspectors concluded that the licensee had an opportunity to detect the flowdiversion through Valve 2PSIB-V405 on October 10, 1997; however, the operators failed to identify the cause of unexpected decrease in SIT level. On October 28, the licensee identified the condition but did not take effective corrective action because of an incorrect assessment of the operability implications. Two examples of an apparent violation were identified for the failure to make log entries for the SIT level decreases, which occurred on two separate occasions while performing the cold-leg boration process. Two examples of an apparent violation were identified for inadequate corrective action to identify and correct a significant condition adverse to qualit 'Jt l

b..

-16-1998 nit 1 Refuelin Outa e and ubse uent eration On April 9, 1998, the licensee had indication of excessive reverse flowthrough Valve 1PSIA-V404 during performance of Procedure 73ST-9X133. The control room received an unexpected equipment drain tank (EDT) high level alarm and the test was suspended.

The licensee concluded that reverse-direction flowthrough the check valve pressurized the Train

"A"ECCS suction piping and the Train "A"containment spray (cs) pump discharge piping to the 650 psig setpoint of Valve 1JSIA-PSV194, the Train "A"shutdown cooling heat exchanger (SDCHX) outlet relief valve. The leak rate through Valve 1 PSIA-V404 was initiallyestimated to be 85 gpm. On April 10, 1998, the licensee initiated CRDR 1-8-0238 to document the event and classified the CRDR as "significant" with action requests to perform an equipment root cause offailure evaluation and reportability determination. During a subsequent engineering evaluation, the licensee estimated that the event resulted in relief valve blowdown to the EDT at a flowrate of approximately 120 gpm and a total leak rate through Valve 1 PSIA-V404 of approximately 214 gpm. The licensee also concluded that the valve body and disc had been in a misaligned condition for the entire previous operating cycle and likely had been misaligned since the last time maintenance was performed on the valve on May 1, 1992. At that time, the licensee had not yet incorporated additional guidance for addressing vertical misalignment concerns for Borg-Warner check valves in the maintenance. procedure. The licensee's review and implementation of in-house and industry operating experience is discussed in Section E1.4 of this report.

The licensee performed Operability Determination (OD) 203 to evaluate the operability impact of the inadvertent pressurization. The OD evaluated the pressure rating and ASME Code allowables for stresses of piping and system components in the HPSI and CS suction piping, CS discharge piping, and SDCHX. The OD concluded that the piping and components remained operable on the basis of not exceeding ASME Code allowable stresses for the suction piping, not exceeding the design pressure for the CS discharge piping, and not exceeding the pressure rating of valves or flanges in the suction piping. The licensee also performed a system walkdown with the HPSI and CS pumps operating to examine performance of the pump seals and pipe flanges. No leaks were identified and no pipe supports exhibited signs of water hammer. The inspectors reviewed the OD and concluded

. that the licensee's evaluation of system operability was acceptable.

. Maintenance technicians disassembled and inspected Valve 1PSIA-V404 via Work Order (wo)

836600 and Procedure 31MT-9ZZ17 on April 10, 1998. With engineering support, the technicians determined that a vertical offset existed in the alignment of the valve disc with respect to the valve body. The licensee concluded that the valve disc had been located too high in the body of the valve and that the disc needed to be lowered approximately 0.5 inch Personnel reverified the calculation for the desired vertical dimensions, but did not independently verify the measurement of the dimensions. The technicians made a measurement error that resulted in an incorrect determination of the magnitude of the vertical offset. Maintenance and engineering personnel concluded that a spacer ring would have to be installed to adjust the height of the disc. Therefore, WO 836600 was amended to Deficiency Work Order (DFWO) 836600 to install a carbon steel spacer ring between the silver plated pressure

. -17-seal ring and the threaded retaining ring to compensate for the vertical offset. Longer bonnet studs were also required to accommodate the spacer. Installation of the spacer ring resulted in the valve disc being located too lowwithin the body of the valve to seat properly. The failure to correctly assemble the check valve to correct the reverse leakage condition was considered to be the third example of an apparent violation of 10 CFR Part 50, Appendix BCriterion XVI(50-528/-529/-

530/9814-03).

A DFWO was the licensee's method forwhich degraded and nonconforming conditions requiring engineering direction were dispositioned and corrected. The licensee considered the DFWO a design change and completed a 10 CFR 50.59 safety evaluation to document that the change did not involve an unreviewed safety question. The inspectors reviewed the DFWO and concluded that it included an adequate evaluation of the acceptability of these subcomponents in the valve. The inspectors asked ifany as-built drawings were revised to reflect the implementation of the DFWO and were informed that the design documents were not changed nor were they planned to be changed. The inspectors were concerned that installation of the spacer and replacement of the bonnet studs without updating any design documentation was representative of inadequate design, control. The licensee informed the inspectors that when a maintenance planner reviews the maintenance history of a component as part of work package preparation, the maintenance history would reveal that subcomponents had been installed or replaced such as the spacer and studs for Valve 1PSIA-V404. The licensee, upon further evaluation, initiated CRDR 9-$4893 to address this issue. NRC review of CRDR 9-8-0893 is considered to be an unresolved item (URI) (50-528/-529/-

530/9814-04). Procedure 73ST-9X1 33 required full MPSI fiowwith the reactor vessel head removed.

t On April 11, 1998, after completion of the DFWO, the reactor vessel head had been reinstalled.

Therefore, plant conditions did not allow the normal, forward flowtest to be performed. An alternate test method was developed in Revision 10 of Procedure 73ST-9XI33 using demineralized water to pressurize the down stream side of the check valve and opening a drain valve on the upstream side of the valve to determine reverse flow. On completion of the test, Valve 1PSIA-V404.was declared operable with a measured leak rate of 18 gpm at a test pressure of 96 psig. The leak rate exceeded an administrative limitof 10 gpm, which in accordance with the test procedure, required the initiation of a work request. The inspectors verified that Work Request 941341 was initiated to repair the valve during the next outage. The licensee informed the inspectors that it had accepted these test results as satisfactory because they assumed that reverse-flow leakage would decrease when HPSI pump discharge pressure from the opposite train improved the valve disc-to-body seat contact during system operation.

On May 7, 1998, the licensee determined during its investigation of CRDR 1-8-0238 that the as-found condition of Valve 1PSIA-V404 on April 9, 1998, represented a condition that would have prevented it from performing its intended function during an accident. The licensee concluded that this event was reportable to the NRC per 10 CFR 50.73 and submitted LER 50-528/98-006 on June 5, 1998. The results and consequences of this assessment are discussed in Section E ~t V

-18-Technical Specification 3.5.2 requires in Modes 1,2, and 3, that two independent ECCS subsystems shall be operable with each subsystem comprised of one, operable HPSI pump, one operable LPSI pump, and an independent operable flowpath. Action statement a.

associated with TS 3.5.2 required that with one ECCS subsystem inoperable, restore the inoperable subsystem to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least hot standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in hot shutdown within the following6 hours. As discussed earlier, Valve 1 PSIA-V404 was installed incorrectly and did not have correct vertical disc alignment from May 1, 1992, until May 15, 1998. Therefore, Train "B"ofthe Unit 1 ECCS did not have an independent operable flowpath from May 1, 1992, until May 15, 1998, and the licensee did not comply with Action a. of TS 3.5.2. This was considered to be the first example of an apparent 'violation of TS.3.5.2 (50-528/-529/-530/9814-05).

G.2 onclusions

'he April 1998, Unit 1 refueling outage test results demonstrated that Valve 1 PSIA-V404 was in a significantly degraded condition. The maintenance history for the subject valve indicated that it had been in that condition since 1992. An example of an apparent violation of 10 CFR Part 50, Appendix B, Criterion XVIwas identified for failure to correct the problem with Valve 1 PSIA-V404 during maintenance. An incorrect interpretation of the 18 gpm April 11, 1998, post-maintenance testing results, contributed to continued operation with an inoperable valve. An example of an apparent violation of TS 3.5.2 was identified for having an inoperable independent HPSI flowpath for approximately 6 years.

nline orrective Maintenance of Valve 1P IA-V404 On May 13, 1998, as part of the CRDR 1~238 review, the check valve engineer reviewed measurements of a spare Borg-Warner check valve and discussed the maintenance procedure and spacer installation with maintenance technicians. The engineer determined that a measurement error may have occurred during the April 1998 maintenance on Valve 1 PSIA-V404, resulting in a vertical disc-to-body misalignment.

The test methodology that was used in Procedure 73ST-9XI33, Revision 10, was extracted and placed in Procedure 73ST-9XI35, Revision 0. Since the Unit 1 refueling outage, engineering personnel had determined that a new acceptance criterion of 30 gpm reverse flow through Valve 1PSIA-V404 would still maintain acceptable HPSI forward flowfor system operability. This was based on an evaluation of the operating performance of the HPSI pumps and system flowcharacteristics.

Procedure 73ST-9X1 35, Revision 0 contained the 30 gpm acceptance criterion. On May 14, 1998, the licensee performed the test on Valve 1PSIA-V404 and it failed with an as-found result of 33 gpm at a differential pressure of 95 psid. The licensee made a one-hour 10 CFR 50.72 notification to the NRC to report that this was a condition outside the design basis of the facility.

After the failed test, the licensee disassembled the valve, removed the spacer ring in accordance with WO 840712, and verified that the disc was misaligned in the valve body. The maintenance technicians performed an inspection and exercised the valve

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-19-internals per WO 840826 and Procedure 73ST-9ZZ25. The technicians then attached a stainless steel wire to the swing arm of the valve, installed the internals with the wire extending outside the valve body (without the silver seal gasket installed), and set the bonnet height.to the desired vertical dimension. When this was done, the technicians stroked the valve by pulling on the wire until a metallic noise was heard, indicating that the disc had contacted the backstop. This provided an additional indication that the valve was free to stroke. The technicians then removed the wire and reassembled the valve with the silver seal to the correct vertical dimensions.

The inspectors noted that WO 840712 was written to disassemble, rework, and reassemble Valve 1PSIA-V404. There were no instructions included to remove the spacer ring. The inspectors asked whether a special WO or WO amendment was required prior to the removal of the spacer ring and whether removing the spacer ring was a design change, as was the case previously for the installation of the spacer ring. The licensee stated that they considered the removal of the spacer to be a rework activity and not a design change. Rework was defined as the process by which a degraded or nonconforming item is made to conform to a prior specified design requirement by completion, machining, reassembly, replacing, or other corrective measures.

The inspectors noted that the materials list for Valve 1PSIA-V404 that was attached to WO 840712 had not been updated to reflect the installation of the new bonnet studs or spacer ring. This issue willbe reviewed as part of URI 50-528/-529/-530/9814-04 to determine whether the licensee implemented adequate design control.

After reassembly of Valve 1PSIA-V404 without the spacer ring, operations performed Procedure 73ST-9XI35, Revision I on May 15, 1998, and the valve passed its reverse flow test with a result of 0 gpm at 142'psid.

onclusions b.4 The questioning attitude of the check valve engineer was instrumental to the identification of the misalignment of Valve 1 PSIA-V404. Corrective actions were taken to restore the valve to an operable condition.

Ino erabilit of Valve 2PSIB-V405 After the April 1998 test failure of the Unit 1 Valve 1PSIA-V404, the licensee initiated CRDR 2-8-0128 and OD No. 204 to evaluate the operability impact of this condition for Units 2 and 3.

Included in this evaluation was a review of past HPSI fullflowtest results conducted during the previous refueling outages and measurement of external valve dimensions. On May 14, 1998, as a result of this review and the results of the Unit 1 testing performed the previous day, engineering and maintenance personnel determined that Valve 2PSIB-V405 was misaligned. Engineering recommended to operations in Memorandum 469-00170-B JR that the valve be declared inoperable, that reverse flowtesting be performed, and that corrective maintenance and post-maintenance testing be performed. The inspectors noted that the memorandum only addressed operability of Valve 2PSIB-V405 and did not address operability of the entire HPSI syste e

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-20-The operators declared the Unit 2 Train "B" HPSI pump inoperable based on the recommendation of the memorandum from engineering-.

The inspectors noted that this was not consistent with the memorandum, which recommended that the Train "B" valve, not the Train 'B" pump, be declared inoperable. The impact of reverse flowthrough Valve 2PSIB-V405 on operability of the Train "A" HPSI system flowpath was not addressed in the Unit 2 log. The licensee informed the inspectors that the Unit 2 log entry only addressed the inoperability of Train "B" because the operators were preparing to perform testing and maintenance on the Train "B"valve, which required removing the Train "B" HPSI system from sefvlc

~lf his check valve'was known to be ino erabfe i wouldhav I

required that the opposite HPSI train flowpath be declared inoperable, if the trains were not isolated, because of the safety function of the valve to close and prevent diversion of flow from the RCS.

The licensee performed Procedure 73ST-9XI35 to measure the as-found condition of Valve 2PSIB-V405 on May 15, 1998. The test results indicated a reverse flowrate through the valve of 37.5 gpm at a differential pressure of 6 psid. As discussed in Section E1.2, this amount of reverse flowwould prevent the HPSI system from meeting the minimum-required ECCS performance assumed in the safety analysis during a LOCA. The licensee issued WO 836005 to disassemble the valve and verified that the vertical alignment of the disc within the body of the valve was too low and had caused the disc to hang in a cocked-open position. The valve alignment was corrected and the valve was retested in a manner similar to that discussed above for Valve 1PSIA-V404. The retest of Valve 2PSIB-V405 passed with a leakage rate of 0 gpm at 150 psid and the system was declared operable on May 16, 1998. As discussed earlier, Valve 2PSIB-V405 was installed incorrectly and did not have correct vertical disc alignment from April 14, 1993, until May 16, 1998. Therefore, Train "A"of the Unit 2 ECCS did not have an independent operable flow path from April 14, 1993, until May 16, 1998, and the licensee did not comply with Action a. of TS 3.5.2. This was considered to be a second example of an apparent violation of TS 3.5.2 (50-528/-529/-530/9814-05).

Conclusions Licensee personnel successfully evaluated and confirmed that Valve 2PSIB-V405 was misaligned and corrective actions were taken to restore the valve to an operable condition.

Testing results demonstrated that the valve was in a significantly degraded condition and the maintenance history for the subject valve indicated that it had been in that condition since 1993. The inspectors considered the communication between engineering and operations a weakness, as demonstrated by the May 14, 1998, memorandum from engineering, which did not provide a recommendation regarding HPSI system operability. An example of an apparent violation of TS 3.5.2 was identifie ll I ~

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b.5-21-l Testin and Vertical Dimension timization of Remainin Valves The licensee performed reverse flowtests of the, four remaining HPSI pump discharge check valves. Allof the valves passed the 73ST-9X135 test with 0 gpm reverse flow. Based on external dimension measurements and a review of previous forward-flow surveillance tests performed during refueling outages, the licensee concluded that two of the four valves, Valves 3PSIB-V405 and 1PSIB-V405, should be reworked for 'Vertical dimension optimization."

Valve 3PSIB-V405 was disassembled, inspected, reassembled to a new desired vertical dimension, and retested with 0 gpm reverse flowon May 18, 1998. When Valve 1PSIB-V405 was inspected and reassembled to the. desired dimension on May 26, 1998, maintenance technicians discovered that the disc was not seating properly. The technicians discovered that the seat angle of the valve was different than expected. Instead of an expected seat angle of 12 degrees, the licensee discovered that this valve had a seat angle of 5 degrees. The licensee contacted the vendor and was informed that all 4-inch Borg-Warner hung-bonnet

'ressure-seal valves were supplied with a 12<egree seat angle. The inspectors questioned the licensee regarding the procurement process and quality assurance receipt inspection for the subject valve. Afterfurther investigation, the licensee determined that the vendor implemented a design change in 1980 that changed the seat angle from 5 to 12 degrees.

Valve 1PSIB-V405 was procured in 1979 and was the only HPSI pump discharge check valve that was built prior to the vendor design change. Therefore, its seat angle was correct. The licensee documented this condition in DFWO 842362. The inspectors willreview the issue of updating design documents regarding this condition as part of the URI regarding'esign control (50-528/%29/-530/9814-04).

The licensee calculated a revised vertical dimension to account for the different seat angle, reassembled the valve and successfully retested the valve with no reverse flow on May 27, 1998.

c.5 onclusions Licensee personnel successfully confirmed that the remaining four HPSI pump discharge check valves were operable by performing reverse-flow tests. Testing performed after maintenance confirmed that the valves remained operable. The licensee adequately demonstrated that one of the valves (Valve 1PSIB-V405) that had an unexpected seat angle, was acceptable for its application and was also operable.

E1.2 Assessment of As-found Conditions Ins ection Sco e

The inspectors reviewed calculations and test results and interviewed engineering personnel to determine the safety and regulatory implications of the as-found degraded condition of the Unit 1 and Unit 2 HPSI system I y I

-22-bservations and Findin s heck Valve Leaka e and De raded HP I

stem Performance The inspectors reviewed Calculation 13-MA-SI-982, "Evaluation ofAllowable Leak Rate Criteria for 1,2,3PSIA-V404 and 1,2,3PSIB-V405/Assessment ofAs-Found Leakage for 2PSIB-V405/1PSIA-V404," Revision 0 and Calculation 13-MC-SI-215, "Revised Single HPSI Pump Delivery Curve for Cold Leg Injection and Flow Rate Requirements forTechnical Specification 4.5.2.h," Revision'1. In Calculation 13-MA-SI-982, the licensee performed a best-estimate evaluation of the current as-built HPSI system delivery profile for each HPSI pump based on historic'al system performance data and compared the resultant delivery profiles to the minimum-required HPSI system delivery profile identified in Calculation 13MC-Sl-215 that was used in the LOCA safety analyses. The margin between the as-built HPSI system delivery capability and the minimum-required HPSI system delivery used in the LOCA analyses was used to estimate a maximum allowable leakage profile for the opposite-train HPSI pump discharge check valve. The results indicated that the most limitingsystem was Train "B" in Unit 3. A maximum leakage rate of 10.2 gpm at 40 psid was determined for Valve 3PSIA-V404, the opposite-train HPSI pump discharge check valve, to ensure that the Train "B" HPSI system would meet its minimum performance requirements.

The licensee also evaluated the April 9, 1998, as-found condition of Valve 1PSIA-V404 and the May 15, 1998, as-found condition of Valve 2PSIB-V405 in Calculation 13-MA-Sl-982. This evaluation concluded that the actual reverse flowrate through Valve 1PSIA-V404 during the-performance of the Procedure 73ST-9X133, forward-flow HPSI refueling outage test, was approximately 214 gpm. Because this test had not been intended to obtain direct differential pressure measurements, it did not provide sufficient data to quantify a HPSI performance curve. However, the licensee had enough information to conclude that the results were qualitatively similar to the results obtained for, the Unit 2 valve as described below.

Valve 2PSIB-V405 had an as-found reverse leakage test result of 37 gpm at 6 psid. The licensee calculated an as-found loss coefficient for the subject valve and developed a HPSI delivery curve that accounted for leakage through Valve 2PSIB-V405. The as-found degraded HPSI delivery curve and the minimum-required ECCS delivery curve are depicted in Attachment 3. As shown, the estimated as-found HPSI delivery capability was significantly degraded compared to the minimum-required HPSI delivery performance that was assumed in the LOCAanalyses. For example, at an RCS pressure of 1200 psig, the estimated HPSI flow rate was approximately 350 gpm less than the flow rate assumed in the LOCAanalyses. The licensee concluded that the results for Unit 1 were comparabl in le Failure Consideration The licensee identified in Calculation 13-MA-Sl-982 that the initial evaluation of the April 9, 1998, Unit 1 refueting outage event included assessments of ECCS suction piping overpressurization, degraded HPSI performance, dose consequences, and impact on containment sump level following a LOCA. The licensee determined that degraded HPSI performance (due to failure of a HPSI pump to start) was the most limitingfactor with which to assess the safety significance of the condition.

The inspectors questioned the basis for the licensee's conclusion. The inspectors considered the failure of an emergency diesel generator (EDG) during a LOCAcoincident with a loss'-offsite power to be the most limiting single failure for consideration since none of the ECCS pumps in the affected train would be operating. (The licensee documented in the calculation that ifthe LPSI and CS pumps associated with an idle HPSI pump were running, the ECCS suction piping would not be overpressurized as occurred on April9, 1998, when the SDCHX relief valve lifted).

The licensee noted that failure of an EDG to start would not be a concern because the RCS loop injection valves associated with the failed EDG would not open and cross connect the HPSI trains.

However, the inspectors noted that under a condition where an EDG failed to continue running after the RCS loop injection valves had opened due to a safety injection actuation signal, a flowpath would be established to pressurize the ECCS suction piping and containment spray pump discharge piping to the SDCHX relief valve setpoint as occurred during the April 9, 1998, Unit 1 test. The inspectors also noted that this event created a release path via the vented RWT through the HPSI

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pump minimum flow line and a loss ofwater inventory to the auxiliary building via the SDCHX relief alve and should be evaluated. The licensee stated that it considered this possible event scenario but determined that it was not necessary to consider the failure of a component to continue running as an assumed single failure.

Section 6.3.1, "ECCS Design Bases," of the UFSAR states that, "Adequate physical separation shall be maintained between the redundant piping paths and containment penetrations of the SIS (safety injection system) such that the SIS willmeet its functional requirements even with the failure of a single active component during the injection mode', or with a single active failure or a limited leakage passive failure; during the recirculation mode."

The bases for TS 3/4.5.2 and 3/4.5.3, "ECCS Subsystems," states, "The operability of two separate and independent ECCS subsystems with the indicated RCS pressure greater than or equal to 1837 psia, or with the indicated RCS cold-leg temperature greater than or equal to 485 'F ensures that sufficient emergency core cooling capability willbe available in the event of a LOCAassuming the loss of one subsystem through any single failure consideration."

The inspectors reviewed ANS-51.7/N658-1976, "Single Failure Criteria. for PWR Fluid Systems,"

ANSI/ANS-58.9-1981, "Single Failure Criteria for Light Water Reactor Safety-Related Fluid Systems," and NRC SECY 77-439, "Single Failure Criterion." The inspectors concluded that guidance existed for application of the single failure criterion

fe

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at required the proposition that single failures can occur at any time. Therefore, the inspectors concluded that the licensee should have demonstrated that its assessment of consequences had assumed the most limiting single failure.

nline Maintenance The inspectors asked the licensee ifthey had performed online maintenance of the HPSI system involving system configurations consisting of an inoperable HPSI pump, the associated discharge isolation valve open, and'the associated RCS injection valves operable (i.e., would open on a safety-injection actuation signal). The inspectors also asked ifthe licensee had considered this configuration as a system v'uln'erability in its event investigation. The licensee reviewed its.

maintenance rule database and provided the inspectors a list dating back to 1994, that identified several occasions when online HPSI maintenance was performed that matched this system configuration. The inspectors were concerned that'during these online maintenance periods, a single failure was not necessary for degraded HPSI performance during a postulated accident. The inspectors concluded that during these periods of maintenance on the Unit 1 Train "A"HPSI system and Unit 2 Train "B"HPSI system (the trains with the reverse leakage check valves) the licensee was in a condition prohibited by the TSs and that TS 3.0.3 required a unit shutdown. The licensee informed the inspectors that it had not evaluated this system configuration as a vulnerability in its event investigation.

The inspectors reviewed the out-of-service data provided by the licensee and noted that the maintenance activities generally consisted of minor preventive maintenance including oil changes, and valve and breaker maintenance. With respect to maintenance on the Unit 1 Train "A"HPSI system (associated with Valve 1PSIA-V404) and Unit 2 Train "B" HPSI system (associated with Valve 2PSIB-V405) the length of time for each occurrence ranged from as short as 0.92 hours0.00106 days <br />0.0256 hours <br />1.521164e-4 weeks <br />3.5006e-5 months <br /> to as long as 19.58 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br />.

The out-of-service data indicated that the Unit 1 Train "A"HPSI pump 'was unavailable when the unit was operating in Mode I on September 4, 1996, for 19.58 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br /> and that no documentation was available to demonstrate that Train "A"was isolated from Train "B."Therefore, the inspectors determined that Unit 1 did not have any independent ECCS subsystem operable when Train "A"of the HPSI system was out of service without isolation from Train "B"of the HPSI system, and Valve 1

'SIA-V404 was inoperable. Action was not initiated to place the Unit in hot standby within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> as required by TS 3.0.3. This was considered to be the second example of an apparent violation of TS 3.0.3 (50-528/-529/-530/9814-01).

The out-of-service data also indicated that the Unit 2 Train "B" HPSI pump was unavailable when the unit was operating in Mode 1 on October 21, 1994, for 19.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. In this case, a clearance order for WQ 6773826 identified that a clearance had been in effect during this period of time that closed the Train "B" HPSI pump discharge isolation valve. The exact length of time that the isolation valve was closed was indeterminate. The inspectors were able to conclude that the isolation valve was closed from between 2.5 to 6.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />. When the clearance order was cleared, the Train "B" HPSI pump discharge isolation valve was opened and the Train "B" HPSI pump was still unavailable due to other maintenance. The inspectors determined that Train "B"of the HPSI system

-25-was unavailable during the maintenance activity and was not isolated from Train "A"for a period of 13.5 to 17.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. Therefore, Unit 2 did not have any independent ECCS subsystem operable for a period in excess of 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> when Train "B"of the HPSI system was out of service without isolation from Train "A"of the HPSl,.system, and Valve 2PSIB-V405 was inoperable. Action was'not initiated to place the Unit in Hot Standby within 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> as required by TS 3.0.3. This was considered to be the third example of an apparent violation of TS 3.0.3 (50-528/-529/-530/9814-01).

Allother examples'of online maintenance of the Unit 1 Train "A"HPSI system and the Unit 2 Train "B" HPSI system were less than 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> in duration. Therefore, while the completion of a unit mode change was riot required, the licensee failed to recognize the applicability of TS 3.0.3.

The misalignment of the Unit 1 and Unit 2 HPSI pump discharge check valves placed the units in a significantly degraded and vulnerable condition with respect to the capability to mitigate the consequences of a LOCA. Two examples of an apparent violation ofTS 3.0.3 were identified.

Assessment of Generic Im lications Ins ection co e The inspectors. reviewed licensee investigation reports, surveillance procedures, and maintenance procedures to determine whether the licensee had adequately addressed the issues of check valve, misalignment and inadequate testing practices with respect to other safety-related valves.

Observations and Findin s The inspectors questioned whether the licensee had evaluated the generic aspects of the misaligned HPSI pump discharge check valves relative to other safety-related valves. The licensee had performed a study of other check valves.,There were 27 Borg-Warner pressure-seal, bonnet-hung check valves installed in each of the three units. None of the valves in this population except for the two HPSI pump discharge check valves per unit had the welded-neck design that appeared most susceptible to the disc-cocking phenomenon. Valves with a forged-neck design did not have vertical alignment variability similar to welded-neck models.

The licensee performed a review of the closed-direction exercise tests for the remaining 25 valves per unit and concluded that the testing performed on each valve adequately demonstrated operability. The licensee also examined a 3-inch valve in the maintenance shop and was unable to reproduce the disc-cocking phenomenon, even with the bonnet retaining ring threaded fully into the valve body. During the inspection, the licensee also initiated a generic review of check valve testing practices to evaluate the adequacy of testing.

The inspectors selected a sample of valves to verify that the surveillance tests were adequate to demonstrate valve closure. The valves chosen for this review were the

If I<

f

-26-LPSI cold-Ieg injection valves (xSIE-V114, xSIE-V124, xSIE-V134, and'xSIE-V144, where 'x's the unit designator) and their associated test, Procedure 73ST-9SI05, "Leak Test of HPSI/LPSI Containment Isolation Check Valves," Revision 4. The test methodology involved pressurizing the downstream side of the valves with a HPSI pump or a hydro test pump and measuring the leak rate on the upstream side. The inspectors determined that the surveillance test was adequate to verify check valve closure.

onclusions The licensee adequately addressed the generic implications of the misalignment issue to other pressure-seal, bonnet-hung check valves to conclude that no additional operability concerns existed.

In-house and lndust EAs Ins ection co e The inspectors reviewed licensee in-house and industry OEAs pertinent to the HPSI pump discharge check valves.

bservations and Findin s NR IN 88-70 " heck Valve Inservice Testin Pro ram Deficiencies" In its January 12, 1989, evaluation of NRC IN 88-70, the licensee identified that reverse flow testing of several check valves, including HPSI pump discharge check Valves 1PSIA-V404 and 2PSIB-V405, was not performed. However, the licensee concluded that because they had an NRC-approved, IST program, any changes the program were considered enhancements.

The licensee did not give this item a high priority and a due date to add these tests to the program was established for 1996. The licensee's quality assurance organization conducted an audit of the check valve programs in 1992, concluded that this schedule for action was untimely, and ideritifled this as'a finding. As corrective action, the licensee initiated action to revise the IST program to include reverse flowtesting of the subject valves. Surveillance Procedure 73ST-xXI29, "Section XI Check Valve Operability Verification - Mode 6-Full Stroke Testing of Safety Injection Check Valves," was approved on July 26, 1992, to conduct the test. The test methodology consisted of measuring forward HPSI flowto the RCS via the hot-leg injection flow path. The HPSI pump discharge check valves were considered operable ifan acceptable forward flowwas measured to the RCS with one HPSI pump operating while cross connected to the opposite train, but no explicit acceptance criterion was included to determine check valve reverse flow.

10 CFR Part 50, Appendix B, Criterion XVI,"Corrective Action," required that measures shall be established to assure that conditions adverse to quality are promptly identified and corrected and in the case of significant conditions adverse to quality that the measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition. The test procedures developed in 1992, as a result of the January 12, 1989, evaluation were not adequate to identify excessive reverse

-27-ow, a significant condition adverse to quality (excessive reverse flowthrough HPSI pump discharge check valves). This was considered to be the fourth example of an apparent violation of 10 CFR Part 50, Appendix B, Criterion XVI(50-528/-529/%30/981443).

R I

"Malfunction of Bor -Wame P essure eal net heck Val s

aused B Vertical Misali nment of Disc" The licensee performed a review of IN 89%2 and concluded that no action was required.

Engineering Action Request (EAR) 89-1 931, completed January 26, 1990concluded that the vendor manuals were adequate and had the necessary steps to ensure original factory-established seat/disc alignment. The licensee's initial screening, documented in an October 9, 1989, memorandum correctly identified that vertical disc/seat misalignment due to incorrect retainer ring position resulted in the problem identified in the IN and that the vendor manual did not include procedure steps for adjusting retainer ring position to achieve the correct alignment. The licensee identified that a review would be performed of check valve maintenance procedures to determine whether a similar problem existed. The licensee documented its evaluation conclusions in the EAR and in a memorandum dated February 15, 1990. The licensee identified that their procedures included instructions for match-marking the valve body and bonnet to ensure alignment of the disc and seat. Therefore, the licensee concluded that procedures contained adequate instructions. This conclusion addressed horizontal alignment concerns but did not consider the vertical misalignment issue and the need to ensure correct retainer ring position.

In 1992, the licensee reevaluated applicability of IN 89-62 and documented in CRDR 9-2~12 that

~

~

~

~

~

~

its original conclusions were incorrect. The vendor had revised its technical manual in October 1990, which included instructions for measurement of the vertical "A"dimension (top of retainer ring to top of valve body) before and after maintenance.

Borg-Warner issued a clarification to its Technical Alert 8909-77-001 (which addressed the vertical seat alignment issue) in a letter to the licensee dated July 8, 1992. The letter stated that the vertical alignment problem was limited to welded-neck check valves (such as Valve 1PSIA-V404) and that the welding of the neck to the body had caused the neck to shrink down, thus causing the bonnet disc assembly to sit lower in the valve body and possibly not seat properly on the valve seat. The licensee issued Procedure 31MT-9ZZ17 on November 30, 1992, which included the Borg-Warner technical alert instructions regarding permanent match marks for horizontal orientation and measurement of the "A"dimension. The licensee's February 15, 1990, evaluation failed to correct an inadequate maintenance procedure for establishing the correct vertical alignment of the valve disc within the valve body of Borg-Warner check valves. The resultant excessive reverse flowthrough HPSI pump discharge check valves was considered to be a significant condition adverse to quality. This was considered to be the fifth example of an apparent violation of 10 CFR Part 50, Appendix B, Criterion XVI(50-528/-529/-

530/9814-03).

l (v

-28-Conclusion The inspectors considered the licensee's OEAs and corrective actions regarding Borg-Warner check valves to have been inadequate in preventing or detecting, in a timely manner, significant conditions adverse to quality relative to the HPSI system. Two examples of an apparent violation of 10 CFR Part 50, Appendix B, Criterion XVI,were identified.

ES E8.1 Miscellaneous Engineering Issues I

Review of Licensee's Followu and i niflicant Investi ation Re ort Ins ection co e The inspectors reviewed the licensee's activities to assess, evaluate, and correct the degraded HPSI system and any potential impact on other safety-related systems. Included in the review was Significant Investigation Report CRDR 1-8-0238, "Excessive Leakage Through HPSI Pump Discharge Check Valve 1PSIA-V404," Revision 0, June 10, 1998. The licensee completed Revision 1 of the report on July 10, 1998, but the inspectors did not perform a detailed review of the report because it was completed following the onsite portion of the inspection.

I bservations and Findin s CRDR 1-8-0238 was initiated to evaluate the April9, 1998, failure ofValve 1PSIA-V404 to satisfy its reverse-flow acceptance criteria. On April 10, 1998, the CRDR review committee classified the subject CRDR as significant. An investigation team was assembled to evaluate the event. The inspectors reviewed the licensee's significant investigatiori report dated June 10, 1998. The licensee performed a thorough historical review of past testing and maintenance practices. The report identified the root cause of the failure of the check valve to be attributed to a common-cause error in assembling the valves stemming from inadequate maintenance instructions. Periodic surveillance testing was ineffective in identifying excessive reverse flow. The root cause of the inadequate surveillance test was an ineffective testing configuration developed by engineering. Missed opportunities to identify and correct problems with the check valves also existed in the form of in-house and industry operating experience reviews.

Revision 0 of the report identified the need for 20 corrective actions associated with this event. As of June 12, 1998, three of the corrective actions had been completed. "schedule for the remaining corrective actions had been developed with planned completion dates ranging from June 21, 1998, through the Unit 3 1998, and Unit 2 1999, refueling outages.

The inspectors noted that the investigation did not identify any problems regarding operator performance with respect to the October 1997, Unit 2 outages or the May 1998, entries into TS 3.0.3. Also, the report did not evaluate the safety consequences

i I

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-29-of performing routine online maintenance of the Unit 1 and Unit 2 HPSI systems when the HPSI trains were not isolated from each other.

The licensee informed the inspectors that additional assessment of the safety significance of the degraded HPSI condition would be performed and the results of the assessment would be documented in the LER supplement.

c.

Conclusions The licensee's investigation report was objective and provided a candid self-assessment of its performance; however, it'did not evaluate inspector-identified issues in the areas of operations or online maintenance.~

I XI Exit Meeting Summary V Mana ement Meetin s The inspectors met with licensee representatives on June 11, 1998, to conduct a technical debrief prior to leaving the site. Following additional in-office inspection, and telephonic discussions of findings, the inspectors conducted an exit meeting with licensee representatives on July 21, 1998. These representatives acknowledged the findings presented, but disagreed with the NIay 13, 1998, apparent violation of TS 3.0.3. The licensee stated that operations recognized that Valve 1PSIA-V404 was in a degraded condition but information existed to conclude that the valve was operable until testing could determine otherwise. With respect to Unit 2, the licensee stated that operations also recognized that Valve 2PSIB-V405 was in a degraded condition but information existed to conclude that the valve was operable until testing could determine otherwise.

The inspectors asked the licensee representatives whether any materials examined during the inspection should be considered proprietary. No proprietary information was identified.

I

)g l

'

rations had reasonable assurance based on valid ST results to consider valve IPSIA-V404 o rable however the c<)nscrvativcl choose to test the valve due to concerns about the valve's rformance The delctinn ofthc first TS 3.0.3 chan cs this statement.

3 fnvesti ation re rt l80238rev.

I states "With thediscmisali ned in thisconfi uration as the valvediscmoved toward thesea u

n cessation of flow the u red eof the valve disccould catch on the inside u red eof the bod seat causin the disc to han u

in the artiall o

n sition."

Pa c 2I ERCFA

'o event has occurred at PVNGS where a HPSI check valve has resulted in reduced HPSI in'ection flow. However reduced HPSI flow would have existed ifa safet in ection had been r uired and the HPSI check vale was cocked o n with theassociated HPSI um not runnin and in ection valves o'.

Thc t<.'rm -ino rable" includes man

>tcntial roblems.

However. Ihe cocked o n check valve nnl resents a roblem ifthe associated HPSI um is not runnin and Uic in'ection valves are o n. This combination ofconditions reduces the likelihood ofa grohlem, Thc term "'ammed" im lies thc valve would not be able to o rate in the o n or closed direction. The investi ation re rt 180238 uses the term "cocked" to describe the check valve condition where the valve would not full close but has no effect on nin the valve.

'The Unit 2 lo cntr states

"Declared the 'B'PSI um ino rablc based nn information received from en ineerin letter ¹46-900I-BJR from Bruce Rash to Pete Borchert that thc dischar e check valve 2PSIBV405 ma be in a condition that wnuld allow cxcessivcback-leaka c."Theins

'ctionre rtstatcmcntismoredefinitivethan whatactuall wasthou htb theo ratorsat the ume

~

~

s The term "rc aired" is used to indicate a corn nent ma not have been returned to the ori inal confi uration but will rform its.

tunction. The term "rework" is used to indicate a com ncnt was returned to its ori inal confi uration. The chan e is made for clarilication since the Unit 2 valve was returne<1 to its nri inal confi uration.

Thc wordin used in the rcfcrcnced document states "... it was determined b 0 rations that there was suflicient evidence to su cst the Ul 404 valve mi ht no

'rform it's function and thc valve was declared ino ndin testin." The use of the term

"would" in thc ins c(ion re rt is misstated and conve s a morc dcfinitc conclusion than what was stated in the document.

It should bc no(ed that this document was not intended to be the oflicial rc )rtabilit determination.

This document was written as a rsonncl statement b

the Re ulatorv Consultant who made thc ENS notification. at the rc uest of the investi ation team to establish when and wh actioiis were (Akcn related to the HPSI check valve rc rtabilitv..

"The condition ol reduced tl<)w <vould only exist ifthe -A" HPSI um wis not runnin~ with the in ection valves n n.

" () 'rations had rcas<uiablc assurance.

b;ised <in valid ST results to consider valve IPSIA-Y404 o

'rable. however thc collsefvrlt)vclv <.'h<x')s<'. (o test th<.'t)lv<) duc to col)cefl)s Alx)ut thc valve's

'rfofmance.

'he LER makes no mcnti<)n ot whv a h)

entry was not made. The chan c is made I'or clarif<c;<(ion.

As lip(ed in nun)ber 8;ilx)vc. thc statement in thc re

)rtahilitvd<)cun)cn( is not <<s dc(i<)itive as itldicated in the ins

'c(ion re

)rt

u)d thcrel'orc no contradiction exists. We believe the correction ot'the I';icts;is noted sllould eh<ulcc this coi)elusion () 'fit(lollsllildfellsonable assur:incc.

based oi) valid ST results to consider valve I PSIA-V404 o

'r;<ble. however thev col)s<.'fviltlv<.'lvch<x)se to test the villvcUUL'o coll<sufi)s <llx)U( th<'. v;llv<.'

'florn)<)lie<.'.

')

'r;i(i<u)s crs<x)<lel h;ive s(;<lcd Ih;il U)c Lnil I hite clltfvi<)to TS 3.()..

\\v:<i;< c<U)scrv;itive;iclion lakeil until An evaluation wAs

)erforn)e<l to <lc(ermine it'U)c en(rv <v;<s rc< uircd. CRDR l803I 7 <vas initi;<tcd;it thc time ot'thc hite entry to have thc condition ev(IIU<I(i.'d.

'" The disch ir ~e chick v ilve would univ<<(I'ect thc o cr<hilitvo('one (r iin ot'PSI not bo(h.

Since thc v ilve <vould:<Il<m I'orw ird tlo<v throuuh (he v;<Ive the;iss<)ci:<ted train o ir;ihili(v<vould not b';i(tie(cd:<nd:i TS 3.0.3 entry would not be rc< uircd at that time,

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Thc ddanc Irom th v ndorcouldonl hc rformcdon a valve which hadnot en install din the.

m ut wa. n tn edas Ucft ln the IN.

'" At thi.

)in i time the v'n or manual was

'in u.e h

the licensee a the valve instru ions

'hi m

.

r m n, in r t in th r

ur a

r suit ofvend rman I

hen fr m IN 9-2

"Th r vi.i w

an nh n

ment ndn im n v lv r

an th r f ren v Iv li nmen revi w r

ir g~rf ~rm g ni 3V n

ni2V4 wr th i

r r ch n in 1994 ni V4 w

m led n

r li neda r

ul f ur h

kValv Pr rm rirt th tedofl kin -95 mdurin rf rmsn of the f rw r'l w Tin UR A

work r c.

w

. Initio in,

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v Iv rin 3R4 Vi l evidence fmisali nm n wa. f un rin hi in i n In rnldimn.ion,wr tkn vl h mth fr B imen,inwihinth wrk rdr t vlv wa.r lin nd r sultedin mrcvera I aka c A th im,ncval ion wa.

rformedofthe rforman candina ionhi, or of

>

her S HP. I v Iv

.

RD 9A-229 an f un at nit 2V404STr ult. hadan indim i n of-4 m I q Thi v Ivewa sched I

f rin.

ion n

r w rkat th n x v ilable win w

I wa. reali n ndr,ul e in mr vcr efl w The oth r4v Iv llh, Tre. I. whi hindi te I

ka e fl mori

. Ad itionall f h v Iv h

nins ted rcvi u.l and er wx no vis> I vid ncc fmi. Ii nment The rocedure w

. sub.e uen I

chan cd, r I

fth e

ins c ion. andeval ati n..

'f r fur er review h licen.

a rcc th, th SITeven.

in Octo r I99 in Unit2wer n rm Iev n.

'3(

r ion. had rca.

na I

.. nn 4sed n valid. Tr.ultsand iffcrence, hc ween the ni I v Ive thad fail it'.

T and the ni 2 valve oconaidcr v. Ivc2PS'IB-V40S rahle, Howev r the conserv ivel chops to

. t he valv ue n

ms aho tthcvalv 'a rf rmqn e in luded in the LER su Icmcn ~

I J

ENCLOSURE 2 NRC REVIEW OF ARIZONAPUBLIC SERVICE COMPANY NRC INSPECTION REPORT MARKUPAND COMMENTS

ji J

,l I ~

The following is a summary of the NRC review of the comments provided by Arizona Public Service Company regarding NRC Inspection Report 50-528/98-14; 50-529/98-14; 50-530/98-14.

No revision. As discussed in the NRC's December 21, 1998, letter to Arizona Public Service Company forwarding a Notice of Violation and Proposed Imposition of Civil Penalty, the apparent violation involving failure to meet the 1-hour requirement of Technical Specification 3.0.3 to make preparations to perform an orderly shutdown was withdrawn. However, the NRC concluded that the circumstances surrounding the issue revealed communication weaknesses between the operations and engineering organizations and could have, under different circumstances, resulted in a situation in which the requirements of the technical specifications would not have been satisfied.

It is not the NRC's practice to revise the inspection report in these situations because the issue was characterized as an "apparent violation."

2.

No revision. See response to Item 1.

3.

Report revised.

Valve disc misalignment resulted in improper valve seating as identified during testing.

Misalignment could have resulted in reverse flowand reduced high-pressure safety injection flow to the reactor coolant system during an accident.

4.

Report revised.

See response to Item 3.

5.

Report revised.

6.

Report revised.

7.

Report revised.

8.

Report revised.

9.

Report revised.

10.

No revision. Assuming a single failure of a failed high-pressure safety injection pump, the reverse flow leakage through the check valve would have resulted in reduced injection flow.

11.

Report revised.

12.

Report revised.

13.

Report revised.

14.

No revision. See response to Item 1.

15.

Report revised.

However, the control room log entry stated, "LCO 3.0.3 should have been entered when both HPSI pumps became inoperable."

This documented that operators had reached a conclusion regarding high-pressure safety injection system operability and applicability of Technical Specification 3. 'I Ii

-2-16..

Report revised.

However, the check valve has a safety function to close and a safety function to open.

In their memorandum to Operations, the engineering staff did not differentiate between these two safety functions.

Rather, the recommendation was simply that the valve be declared inoperable, which could imply that both safety functions were affected.

The memorandum did not include a discussion of the capability of the valve to allow forward flow.

17.

Report revised.

18.

Report revised.

19.

Report revised.

20.

Report revised.

21.

Report revised.

22.

No revision required.

23.

Report revised.

The memorandum from Engineering clearly provided a recommendation to Operations that the valve be declared inoperable.

24.

No revision require t

) ~

t

il

'N

ENCLOSURE 3 REVISED NRC INSPECTION REPORT 50-528/98-14; 50-529/98-14; 50-530/98-44

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