IR 05000309/1985019

Insp Rept 50-309/85-19 on 850808-16.Violation Noted:On 850807,9 of 12 Root Valves for Steam Generator Pressure Instruments Not Fully Open

ML20134N995
Person / Time
Site:	Maine Yankee
Issue date:	08/26/1985
From:	Elsasser T, Ferlic K, Holden C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20134N986	List: IR 05000309/1985019 ML20134N983
References
50-309-85-19, NUDOCS 8509060101
Download: ML20134N995 (7)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

Docket / Report: 50-309/85-19 Licensa: DPR-36 l

Licensee: Maine Yankee Atomic Power Company 83 Edison Drive Augusta, Maine 04366 Inspection at: Maine Yankee Nuclear Power Plant, Wiscasset, Maine Dates: August 8-16, 1985 Inspectors: W ftids(nu t/s 4 /er C. Holden, Senior Resident Inspector Date il P Rdk S/r 6//s~

K. Ferlic, Project Engineer Date Approved by: *: _

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T.C.Elsasseghip,ReactorPr ectslection 3C ' Dat'e Summary: Inspection Report 50-309/85-19 (August 8-16, 1985)

Areas Inspected: This special inspection (82 hours9.490741e-4 days <br />0.0228 hours <br />1.35582e-4 weeks <br />3.1201e-5 months <br />) was conducted to determine the circumstances surrounding the discovery of nine of the. twelve root valves for the steam generator pressure instruments that were not fully open and may have been shut. The inspection involved a review of plant systems involved, documentation reviewsc and interviews with plant personne Results: One violation was found.

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DETAILS Description of the Event On August 7, 1985, the control room operators noted that the steam generator ,

(S/G) pressure indication for S/G #1 Channel "D" was reading approximately

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520 psig on tho sigma meter on the main control board. The three other sigma meters for #1 S/G and the eight sigma meters associated with #2 and #3 S/G were all reading approximately 630 psig. The operators. reported the deficiency to the Instrument and Controls (I&C) section via Discrepancy Report (DR)

1. 3777-8 I&C technici'ans conducted a calibration of the pressure detector using Proce-dure 3-6.2.1.2, Protective and Safeguard Channel Calibration, Steam Generator Pressure, Revision 10, dated June 13, 1985. The calibration was satisfactory and the technicians suspected that the instrument line may have been blocke Using the drain line, the technicians blew down the line and found that after an initial volume of water was drained, the steam pressure in the line was minima After discussions with the control room, an operator was sent to the mechani-cal penetration room at 7:30 p.m. on August 7, 1985, to check the position of the instrument root valve. I&C technicians routinely operate instrument isolation valves (near the instrument) and plant operators manipulate the root

~' valves (near the connection to the process).

, The operator, suspecting that the valve for S/G #1 Channel B was open, at-l tempted to verify it as open by turning the valve in the open direction and discovered the valve was, in fact, not open. The exact position of the valve

, is not known but the operator believes the valve (MS-46) was moved through it~s entire range of travel as he opened it. The next valve checked was MS-47 which was also checked in the open direction and was found to be similar to MS-46. As a result, the remaining root valves were initially checked in the

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shut direction in an attempt to verify their positio All root valves (four for each of the three S/G's) were checke Three valves were found open (MS-45, 65, and 85). These three valves are the Channel "A" pressure detector root valves. The other nine root valves were found nearly shut. The operator reported moving a number of valves approximately 1/16 to 1/32 of a turn in the closed direction. Full stem travel is approximat'ely 5 and 1/2 turns. The operator reported that three valves were found open, six valves (MS-44, 64, 66, 84, 86, 87) were found cracked open and three valves (MS-46, 47, 67) were closed. Of the three valves reported as found

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closed, two were checked in the open direction and therefore-the original position is indeterminate. The third valve reported as closed is physically difficult to operate because of nearby pipe insulatio ~

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3 Immediate Corrective Action The control room directed the operator to open/ verify open all of the steam ,

generator pressure root valves (this was done in conjunction with checking the valve position as described above). The root valves for S/G pressure were

, then tagged in the open position within one hou Using the instruments described in Tables 4.1-1, 2, and 3 of the Technical Specifications (TS) the operators established a list of safety related in-strument Those instrument root valves which were accessible were checked for proper positio The instrument root valves that were not accessible were verified open by establishing the operability of the associated instrumenta-tion. Some of the instrument root valves were controlled by plant procedure These procedures were checked to ensure these valves were in fact verified open by that procedure the last time it was performe The three plant procedures which controlled root valve position are Procedure 1-12-2, Containment Leak Monitoring; Procedure 1-12-5, Establishment of Con-tainment Integrity; and' Procedure 3-1-2, Emergency Core Cooling Routine Test-ing. The combination of these three procedures either provides for routine checking of the instrument root valves or verifies the position of those valves at the conclusion of the outage and prior to plant startup. The total number of root valves checked by these procedures is 10 The total number of saf?ty related root valves is 20 Out of the sixteen systems identified by the licensee as safety related systems", these procedures cover only three of those system The event was presented at the morning managers meeting on August 8, 1985, and a special review of the event was begun. The operability of the other-instruments was the first issue aadressed. A critical review of the list of root valves was undertaken and available evidence of the operability of the instruments associated with the inaccessible root valves was presented to a PORC meeting held on August 9, 198 The instrument root valv53 that were inaccessible and did not allow actual visual inspection of valve position were Pressurizer Level and Pressure, Safety Injection Tank (SIT) Level and Pressure, and S/G Level and Reactor Coolant System (RCS) Flow. The root valves for these instruments are located in high radiation areas in containment when the plant is at powe Pressurizer Level and Pressure Instrumentation were checked using log readings of system response during plant heatup, chart recorder traces, post trip re-view and sequence of events data from the plant computer which recorded the fluctuation of pressurizer level during a plant trip on November 3, 1984. SIT Level and Pressure are trended using a manual plot of levels and pressures over the operating cycle. These plots were reviewed and determined to be characteristic of SIT fluctuations over the cycle. RCS Flow was similarly determined to be characteristic *of expected performance based on previous startup data anu current instrument readings. S/G Level instrumentation was checked using plant trip data from November 3 and November 11, 1984 which

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showed all low level S/G trips actuated.

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. Steam Generator Pressure Instruments and Plant Protection Steam generator pressure provides several protection signals in the event of a main steam line break. The three main steam lines exit containment into the Mechanical Penetrations Room where each line is provided with an isolation i

Non-Return valve and an Excess Flow Check valve. Each of these steam lines has four instrument taps between the Non-Return Valve and the containment wal Each instrument tap contains a root valve, instrument isolation valve, a pressure transmitter, and a drain valve. These four instrument taps provide the pressure signal for the four independent measurement channels A, B, C, and Each independent measurement channel provides the following:

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Pressure indication on the main control board (MCB) sigma meter for each

! steam generator. (Sigma meters are a brand name of a small horizontally mounted meter. All twelve sigma meters are located in the same area of the MCB so that all channels can be easily compared.)

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An input to the Reactor Protection System (RPS). The low S/G pressure trip setpoint is 485 psig. RPS logic is any 2 of 4 low S/G pressure 1 signals on any two independent protection channels from one or more steam generator ,

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Independent'of RCS:

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An input to close all Excess Flow Check Valves on low pressure (400 psig) from a single steam generator and provide a pre-trip alarm

(535 psig). Signal is any 2/4 from a single steam generator.

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A low S/G pressure signal to provide a feedwater isolation signa , Signal is 2/4 from a single steam generator.

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A low S/G pressure signal coincident with a safety injection actu-ation signal to provide a main feedwater pump train trip. Signal is 2/4 from a single steam generato In addition to the above, Channel A provides an input to the plant computer,

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indication on the Appendix.R Safe Shutdown Panel and a second meter on the MC .

4. -Event Analysis

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' During the last refueling outage, completed in June of 1984, several modifi-cations were made to the systems involved in this event. The first was the installation of additional valves in the auxiliary feedwater system for the feedwater trip system. -The addition of these valves necessitated a S/G hydrostatic tes The second modification was the installation of the Safe

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Shutdown Panel for Appendix R. This modification installed an additional pressure transmitter in each of the Channel "A" S/G pressure sensing line These transmitters provided S/G pressure indication on.the Safe Shutdown Panel.

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i The plant controls S/G hydrostatic tests using two procedures. The first procedure, Procedure 4-1-4, Hydrostatic Fill and Te't, s Revision 0, dated May 24, 1984 provides guidance on the filling, venting, and aligning of the S/ It is intended to cover the realignment of the feedwater, main steam, and S/G blowdown systems. This procedure requires the root valves for the S/G pres-sure instruments to be closed by operations personnel and the instrumentation valves for the S/G pressure and level instruments to be closed by I&C per-sonnel. The procedure does not address the closure of the S/G 1evel trans-mitter root valves and therefore these valves were not manipulated during the test. At the conclusion of the test, Step 8.3.6 directs I&C to place the individual level and pressure transmitters back in service. Each transmitter was initialed as returned to service in Step 8.3.6. Step 8.3.7 directs the Aperations Department to realign the affected systems but does not identify the individual valves to be manipulated. Specifically, this step states

" Realign steam, feedwater, and blowdown systems for normal operation."

The second procedure used during a S/G hydrostat_ic test is Procedure 17.25, System and Component Pressure / Leak Test, Revision 1, dated May 1, 1984. This procedure dictates the acceptance limits, the sequence of activities required to perform the test and the verification that the systems satisfy the design requirements of the hydrostatic test. In Section 10 of this procedure I&C is required to return the pressure and level transmitters to service. In-strument root valves are not addressed by this procedur The insoector concluded, based on the above information, that all root valves for S/G pressure had been shut for the hydrostatic tests of the S/G's which were conducted on or about May 31, 198 Since both procedures associated with the hydrostatic te'st do not require the root valves to be opened at the completion of the test, they remained shut. Channel "A" S/G pressure root valves were opened on June 7, 1984.when tagout 742-84 was cleare Low S/G pressure instrumentation was required to be operable for the Reactor Protec-tive System on June 22, 1984 at approximately 11:00 p.m. when the plant in-creased power above 2 percent. Low S/G pressure instrumentation was required to be operable on June 20, 1984 for the Feedwater Trip system wnen the boron concentration of the plant was reduced below the hot shutdown boron concen-tration. Since the root valves for the low S/G pressure channels B, C, and D were left in the closed position, these channels were not available to perform their intended safety function. This is a violation of Technical Specifications 3.9 and 3.2.2 (VIO 309/85-19-01).

Interviews conducted by the inspector determined that the operational philo-sophy at Maine Yankee concerning instrument root valves has been that these valves are intentionally open, remain open, and instrument operability checked during startup by the operator's assessment of control board indication Consequently, the licensee determined that there was no need to add root valves to system lineups or administrative 1y controlled valve lists. Instru-ment isolation would be accomplished by I&C personnel utilizing the instrument isolation valvs in accordance with approved procedures or by operations per-sonnel closing, and subsequently opening, the root valve in accordance with !

the plant tagging procedures. Some instrument root valves (containment )

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hydrogen monitor, RWST level indicator, and containment pressure) were added to the valve list in specific procedures to address a specific requiremen Consequ'ntly, e when Step 8.3.7 of the hydrostatic procedure that required the operator to: " Realign steam, feedwater, and blowdown systems for normal oper-ations," it was not clear with regards to requiring manipulation of the root valves after completion of the procedur These valves are not manipulated in alignment for normal operation . Exit Interview Meetings were periodically held with senior facility management to discuss the inspection scope and findings. A summary of the findings was presented to the licensee at the end of the inspectio .