IR 05000423/1987010

Insp Rept 50-423/87-10 on 870504-08.No Violations Noted. Major Areas Inspected:Licensee Activities Re Prior Problem Areas Associated W/Snubbers,Porvs,Main Steam Safety Valves & Control Room Pressurization Sys

ML20215F168
Person / Time
Site:	Millstone
Issue date:	05/28/1987
From:	Gregg H, Strosnider J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20215F145	List: IR 05000423/1987010 ML20215F142
References
50-423-87-10, NUDOCS 8706220268
Download: ML20215F168 (7)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

Report N /87-10 Docket N License N NPF-49 Licensee: Northeast Nuclear Energy Company P. O. Box 270 Hartford, Connecticut 06141-0270 Facility Name: Millstone Nuclear Power Station, Unit 3 Inspection At: Waterford, Connecticut Inspection Conducted: May 4-8, 1987 Inspectors: y 5//B/87 f arold 1. Gregg, Lead Reactor Engineer date

Approved by: f/EE/57 R. St'rosnider, Chief, Materials and

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date Processes Section, EB, DRS Inspection Summary: Inspection on May 4-8, 1987 (Inspection RepotL No. 50-423/87-10).

Areas Inspected: A routine unannounced inspection was conductua to (1) review licensee activities related to prior problem areas associated with Snubbers, Power Operated Relief Valves (PORVs), Main Steam Safety Valves (MSSVs), and Control Room pressurization systems; (2) review the r.' ent snubber visual surveillance data; (3) review the repair work pertaining to the aforementioned equipment and make independent observations of the equipment; and (4) to assess the effectiveness of the licensee's action .Results: No violations were identifie PDR ADOCK 05000423 G PDR

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DETAILS 1.0 Persons Contacted 1.1 Northeast Nuclear Energy Company (NNECO)

Millstone Unit 3 P. Atkinson, Engineer

• K. Burton, Operations Supervisor

• C. Clement, Unit Superintendent

• T. Cleary. Engineer E. Fetterman, Shift Supervisor

• M. Gentry, Assistant Engineering Supervisor

• J. Harris, Engineering Supervisor N. Hulme, Senior Engineer S. Jonasch, Maintenance Engineer

• D. Moore, Operations Assistant

• R. Rothgeb, Maintenance Superintendent J. Short, Maintenance Foreman R. Vanwey, Maintenance Engineer 1.2 Northeast Utilities Service Company (NUSCO)

P. Quinlin, Senior Piping Systems Engineer 1.3 Westinghouse Nuclear Energy Systems Service Division J. Moore, Site Service Manager U.S. Nuclear Regulatory Commission

• J. Shediosky, Senior Resident Inspector

• Denotes those present at exit meetin .0 Snubber Inspection 2.1 First Visual Surveillance The inspector reviewed the licensee's evaluation of the first snubber visual surveillance. This surveillance was performed during the July / August 1986 plant shutdown in accordance with the Technical Specification (TS) requirements for a visual inspection within 4 to 10 months after commencing Power Operatio .

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The findings of the licensee's first inspection revealed boron crystal deposits on the bodies' of numerous snubbers due to leaking valve packing. These snubbers were functionally tested to verify operabilit The surveillance results for the plant's 1148 snubbers-(44 Paul Monroe hydraulic and 1104 Pacific Scientific (PSA) mechanical)

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-0 inoperable hydraulic snubbers-2 inoperable mechanical snubbers of the PSA 1/4-1/2 type-2 inoperable mechanical snubbers of the PSA 1-10 type-0 inoperable mechanical snubbers of the PSA 35-100 type These results mandated the next visual surveillance period to be 6 months 125% for both the PSA 1/4-1/2 and the PSA 1-10 type mechanical snubber .2 Second Visual Surveillance The licensee's second visual surveillance was performed in the mid-March to end-of March 1987 outage in accordance with TS requirement From discussions with cognizant licensee personnel and from review of the inspection records, the inspector determined the licensee visually inspected all type snubbers even though there was only the requirement to inspection the PSA 1/4-1/2 and PSA 1-10 type The inspector reviewed the results of the licensee's second visual surveillance dated April 2,1987, and noted that there were 25 PSA mechanical snubbers that exhibited some signs of impaired operabilit Similar to the prior inspection the predominant problem identified was boron crystal deposits due to leaking valve packing. All 25 snubbers were removed, tested and replaced. Based on the testing, 2 snubbers were locked in' position and were determined inoperable and one snubber was unsatisfactory'due to high drag forc The licensee contracted with Paul Monroe Company to disassemble and evaluate the 3 snubbers. The report was not finalized at the time of this inspectio The licensee's final evaluation will be based, in part, on the vendors forthcoming data. The visual findings thus far were:

-0 inoperable hydraulic snubbers-2 inoperable (frozen) mechanical snubbers of the PSA 1/4-1/2 type-1 inoperable (high drag) mechanical snubber of the PSA 1/4-1/2 type-0 inoperable mechanical snubbers of the PSA 1-10 type-0 inoperable mechanical snubbers of the PSA 35-100 type

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Based on.the test results the next' inspection interval for the PSA 1/4-1/2 type will be a maximum of six months i25%, and possibly 4 months 125% if the high drag snubber is evaluated as inoperabl For the other types, the inspection interval could be 18 months 125%.

The licensee is planning to perform snubber work during the coming November 1987, refueling outage. They intend to remove 150 mechanical snubbers as part of a snubber reduction program and to remove 10 mechanical snubbers due to the planned RTD bypass removal. The  ;

licensee also is planning to install protective covers on the i mechanical snubbers and indicated this would be done during the l

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coming refueling outag The boric acid leakage problems identified by the licensee could '

potentially have adverse affects on other equipment, e.g. hangers, bolting and piping. This concern was related to the licensee in a telephone conversation subsequent to the conclusion of this inspectio This item is unresolved pending NRC review of: 1) the licensee's final evaluation of the second visual snubber surveillance, 2) the licensee's resolution of the boric acid problems. (50-423/87-10-01)

3.0 Licensees Activities Related to Previously Identified Items l 3.1 (Closed) Unresolved Item 86-29-03, Main Steam Safety Valves (MSSVs).

This item was unresolved pending verification that the resetting of the MSSV rings to -8 notches on the lower ring and +160 notches on the upper ring are correct and that the Plant Incident Report (PIR)

and Licensee Event Report (LER) were complete The inspector reviewed the completed PIR 240-86, the completed LER 86-043, and the Dresser Valve Division letter dated November 12, 1986, relating to the MSSV ring setting The Dresser letter recommended the -8 (lower ring) and +160 (upper ring) ring positions

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based on testing. The inspector verified from automated work orders l

M3-86-08578, 08579, 08580 and 08581 that the plant's 25 MSSVs (20 installed - 5 for each steam generator and 5 spares) had their rings reset to the -8, +160 settings. The inspector also observed the 20 installed MSSVs located in the main steam valve building at the 81' ,

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elevation. These MSSVs are 6" x R x 8"/8" (double outlet valves) and each outlet path has a metal bellows attached to a stack ven This item is close .2 (0 pen) Unresolved Item 86-29-02, PORV Leakage Problems. Inspection Report 86-29 described the problems encountered with the Crosby /

Garrett pilot operated relief valves (PORVs). That report also discussed the design rework performed prior to startup, leakage

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. 5 encountered after startup, inspection findings and interim repairs made during the August 1986 outage. This i_ tem was unresolved pending successful completion of more repairs to be done during the March 1987 outag The inspector verified that high leakage ~through valves 455A and 456 (the plant's 2 PORVs) continued after the August 1986 startup. The outlet temperatures of these PORVs valves reached 240 F and they were isolated using the upstream bicek valves in November 1986 due to the high temperatures. During the March 1987 outage, the PORVs were disassembled, inspected and repaire The inspection of the removed PORVs revealed steam cutting on the plug at the seating surface (the plug in valve 456 was the worst) and evidence of leakage of the solenoid to body; gasket joints of both valves. Testing of the removed solenoids was attempted but they leaked internally to the extent that test pressure buildup could not be achieve The PORV repairs during this outage consisted of replacement of the Stellite 6B seats with Inconel 718 seats, re-machining of the plug, lapping of the plug to the seat, installation of new solenoid assemblies and installation of new gaskets at each gasket joint. The new solenoid assemblies were bench leak tested in energized and de-energized positions with 2600 psig water prior to assembly on the POR Both solenoid assemblies were leak tight. Each assembled PORV (with solenoid) was bench tested with water at 2250 psig and was leak tigh Since plant startup on April 4, 1987 to the time of this inspection exit on May 8, 1987 the valves have been tight and have not been isolated. The PORV outlet temperatures have been relatively stable (around 130 F - 140 F). The inspector verified the temperatures several times during the inspection. The control room readout from sensors in a downstream header was 115 F and the analog readout from special sensors placed close to the outlets were 137 F maximum. This is far less than the 240 F readings taken when the PORVs were known to be leakin Based on discussion with cognizant licensee personnel the inspector learned that the vendor has completed calculations for a flexitallic

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type underseat gasket to replace the existing grafoil/ metal gaske The seat is held in place with ten 1/4"-16 UNC socket head cap screws which also apply a seating force to the underseat gasket. All the other PORV gaskets of this type have already been replace However, the vendor will not release the new gasket design until testing verification is performe (The underseat gasket is a thin metal gasket with thin 1/16" - 1/8" wide circular strips of grafoil - 2 on one side and one on the other side. (A new storeroom gasket examined by the inspector was warped by at least 1/2"). The licensee previously has experienced problems with this gaske l

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During the March 1987 outage and PORV inspection,'the licensee l identified leakage at the solenoid to valve body joint. The solenoid assembly is attached to the valve body by (2) 1"-8UNC studs and nut The 2 studs are in the horizontal position and straddle 3 flexitallic

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type gasketed passages which are in a vertical alignment. The licensee attributes the problem to not having the current valve holding fixtures to enable centering of these gaskets when the solenoids were attached to the valve .

This item remains open pending: 1) resolution of the present underseat gasket issue, and 2) resolution of the solenoid / body gasket joint leakag .3 (Closed) Unresolved item 86-29-01, Evaluation of First Snubber Visual Surveillance. This item was unresolved pending evaluation ,

and disposition of the surveillance findings.- )

The licensee provided the inspector the Evaluation of Snubber Test Results dated, November 5, 1986 as described in paragraph 2.0. The-inspector reviewed the evaluation, including the test data and disassembly inspection record for each snubber that had visual signs of impaired operabilit The inspector determined that the testing performed and the evaluations made to assess both system operability and snubber operability were in accordance with TS requirement Additionally, the inspector determined the licensee's evaluation of two (2) failures of the PSA 1/4-1/2 type, and two (2) failures of the PSA 1-10 type were correc Based on these results the next visual surveillance was set.at six months 125% for these two types of snubber The inspector concluded the evaluation was acceptable and in accordance with the T The inspector observed several snubbers in the main steam valve building. Snubbers observed were PSA-100 (Serial Nos. 1516, 1514, 1518 and 1521 on the feedwater bypass line at elevation 52'; and PSA 10 (Serial Nos. 15165 and 23853) on the main steam pressure relief control valve line at elevation 76'. The inspector verified that these snubbers had no visual signs of impaired operabilit This item is close _ _ _ _ _ _ - _ - _ _ _ _ _

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I 3.4 (Closed) Unresolved Item 85-54-02, Control Room Emergency Ventilation System and Control Room Envelope Pressurization System. This item was unresolved pending clarification of leak rate requirements, completion of the leak rate tests and analysis of the leak rates to verify system operabilit The inspector reviewed the TS 3/4.7.7 and TS 3/4.7.8 surveillance l'

requirements for the control room ventilation and pressurization system. The inspector determined: 1) that TS 3/4.7.7e.2 requires verification that each of the two emergency ventilation systems can maintain the control room at a positive pressure of 1 1/8 inch water gauge (W.G.) at a pressurization flow of < 230 cfm, and 2) that TS 3/4.7.8.c.2 and 3 require verification that the 1/8 inch W.G. can be maintained for 3 60 minutes for each of the air bottle system The inspector verified that the February 1987 test results of these systems were within the acceptability requirements. Additionally, the inspector made observations of the control room east and west doors (351E and 352W), and the mechanical equipment door (353E) and verified that revised administrative controls were in place to assure these doors are dogged during a Control Building Isolatio This item is close .0 QA/QC Interface The inspector reviewed the extent of QC oversight in each of the areas inspected. The snubber surveillance was contracted to Westinghouse and the procedures require records of visual inspection (Nuclear VT-1) dat The inspector verified that the surveillance personnel were qualified to

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VT-1 to VT-4 levels and that the snubber removal, test and installation l procedure contained QC hold and witness point The inspector also verified that the AW0s #or all safety QA Category 1 items required QC inspections and that QC was involved in each of the items reviewed during this inspectio .0 Exit Meeting The inspector met with the licensee's representative (identified in paragraph 1.0) at the conclusion of the inspection on May 8, 1987, to summarize the findings of this inspectio The NRC Senior Resident Inspector, J. Shediosky, was also in attendance.

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