IR 05000410/1986067

Insp Rept 50-410/86-67 on 861201-05.No Violations Noted. Major Areas Inspected:Followup of MSIV Problems.Problem Re Seat Spool Packing Identified.No Judgement Could Be Made Re Actions Taken to Correct Ball Scoring Problem

ML20212H747
Person / Time
Site:	Nine Mile Point
Issue date:	01/09/1987
From:	Gregg H, Strosnider J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20212H743	List: IR 05000410/1986067 ML20212H739
References
50-410-86-67, NUDOCS 8701280005
Download: ML20212H747 (7)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

Report N /86-67 Docket No. 50-410 License No. NPF-54 Priority -

Category B Licensee: Niagara Mohawk Power Corporation 300 Erie Boulevard West Syracuse, New York 13202 Facility Name: Nine Mile Point Nuclear Power Station, Unit 2 Inspection At: Scriba, New York Inspection Conducted: December 1-5, 1986 Inspectors: O H. I. Gregg, L(ad Reactor Engineer '

'date Approved by: / 87 g/ R. Strosnider, Chief, Material & Processes date (/ Section, Engineering Branch, DRS Inspection Summary: Inspection on December 1-5, 1986 (Inspection Report No. 50-410/86-67)

Areas Inspected: This inspection was a routine unannounced follow up inspec-tion of licensee's activities related to Main Steam Isolation Valve (MSIV)

problems. The inspection reviewed the licensee's installation of MSIV in-ternals and the preliminary leak test results obtained since license issuance, obtained information on new problem areas, obtained results of actuator tests, made observations of valve coraponents and assessed the licensee's corrective action Results: No violations were identified. A potential problem concerning the seat spool packing has been identified and will require continued attentio Also, there has been limited cycling of any of the valves since reinstallation of internals and no additional judgement could be made concerning the accept-ability of the actions taken to correct the prior ball scoring proble *

8701280005 870116 PDR ADOCK 05000410 G pop

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DETAILS 1.0 Parsons Contacted 1.1 Niagara Mohawk Power Corporation (NMPC)

• P. Abbott, Station Superintendent C. Beckham, Operations QA Manager

• Hansen, Manager Nuclear QA Operations

• Klein, Manager Project Engineering

• Pinter, Site Licensing Engineer

• D. Terry, Manager, Nuclear Engineering & Licensing

• Wilde, QA Audit Group Lead 1.2 Stone & Webster Engineering Corporation (SWEC)

T. Arrington, Resident Manager FQC

• C. Crocker, Project Engineer M. Fachada, Lead Power Engineer

• D. Koehl, Lead Advisory Engineer SU & Test S. Leor,ard, Project Engineer J. Panchison, Principal Mech. Eng G. Rodgers, Principal Materials Engineer 1.3 New York State Electric and Gas

• P. MacEwan, Site Representative 1.4 Public Service Commission

• P. Eddy, Site Representative U.S. Nuclear Regulatory Commission

• Cook, Senior Resident Inspector

• Schmidt, Resident Inspector

• Denotes those present at exit meetin .0 Main Steam Isolation Valves (MSIVs) Inspection 2.1 Inspection Objectives The objective of this inspection was to obtain an update on the MSIV repairs, review the latest leak test results, review both old and new problem areas, and assess the licensee's activities regarding the MSIV r;

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2.2 Background A prior Region I inspection (50-410/86-53), reviewed the background history of this new Ball Type 24" MSIV and the problems identified by Nine Mile Point Unit 2 (NMP-2) relating to the valve internals (seat leakage / ball galling and scoring) and the actuator (mechanical latch /long closure time). Repairs to the valve included changing the seat springs, refurbishing of the balls and seats, and utilizing a hydraulic ac.uating system (mechanical latch eliminated). Test re-sults of one valve cycled 75 times gave good results. However, the report concluded that a test of one valve did not provide adequate confidence to conclude that the problems were fully corrected. It was anticipated that more design modifications and verification testing could be necessar Subsequent to inspection 50-410/86-53 an operating license was granted that contained several conditions including additional leak testing'and separate full scale protoype valve test There were also requirements to provide satisfactory solutions and testing verifications of the outstanding Construction Deficiency Reports (CDRs) concerning these valves (i.e., 86-00-18, 86-00-19, and 86-00-20).

2.3 Current Inspection Areas During this inspection, the latest leak test data was reviewed, observations were made of assembled MSIVs and parts, information was obtained on new problems and implemented or proposed corrective ac-tions and discussions were held with cognizant personnel regarding MSIV issues. The inspection findings are as follows:

Results of the after repair leakage tests of the first 4 as-sembled valves (valve 6A, 68, 6C and 7D) were reviewed. These valves had Chesterton 1000C seat packing. Seat leakage was minimal (less that 3SCFH).

An axial alignment problem was encountered with the Serial No. 4 ball when it was placed in valve 7B and high leak rate was en-countered. The licensee stated the cause of the problem was the use of a new bonnet that was incorrectly machined. The bonnet was subsequently machined to correct the problem. Observations by the inspector were made of this ball which was in the ware-house. The markings observed on the ball and trunions were consistent with those expected as a result of axial misalignment due to the bonnet. (Prior to placement in valve 78 when the bonnet problein was encountered, the serial No. 4 ball had been placed in valve 60 where there was a problem of marking of the ball, termed Stellite smearing by the licensee. The cause of smearing was undetermined and the ball was re-burnished by the vendor.)

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. 3 A problem was encountered with a replacement batch of Chesterton 1000C seat packing that was received wet. After attempts to dry this packing at the site failed and a new batch couldn't be obtained in time to meet the schedule, a new packing material, Latty Tex 117, was obtained from another manufacturer for use in the remaining four valves (6D, 7A, 78, and 7C).

The leak test results of the four valves with the Latty Tex 117 packing material were all in the range of 4.7 to 6.0 SCFH. The leak rate limit is 6 SCFH; however, these leak rates were higher than those for the first 4 valves. The higher leak rates could be attributed to the use of the new packing. The assembly of these valves was different from the first four insofar as the ball was jacked into an intermediate position prior to releasing the seats (in the first 4 valves there was no jacking of the ball prior to releasing the seats). However, it was the packing that was considered the cause of the higher leak rat The Latty Tex 117 and Chesterton 1000C packing materials were reviewe The Latty Tex is a fully graphited asbestos braided packing with an Inconel wire inser It appears to be more densely packed than the previous Chesterton type which also ap-pears to be only surface graphite The packing dies and the press were observed (packing is cut and additionally set at NMP-2).

Additional revisions were made to the hydraulic actuation sys-tems per E&DCR M10030C. The inline jockey pump check valve was changed to a Nupro valve. (The original Circle Seal valve had problems with the 0 ring seat rolling up on the disc.) The relief valve was changed to a Crosby type. (The original relief valve had problems with set point drift.) Finally, an external orifice was placed in the fitting at the rod end of the hy-draulic cylinder to control the closing tim (The original closing time after changing the seals and porting at the rod end was too fast and a 7/8" orifice placed in the external fitting corrected the closing time to the required 3-5 seconds.)

It was determined that the partial stroke testing was changed from the 12 from full open position to approximately 7 . This change was made because the 12 partial stroke test corresponds to the worst case for seat stabilit *

Attempted video probe viewing of valve 6C was observed. The orientation and manipulation of the probe was difficult and the viewing wasn't deemed effective. However, this was the first attemp *

Information on the planned preoperational cycling of the valves, and surveillance requirements during operation was obtaine .

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A test hydraulic system at Crosby was tripped after a planned 38 day inactive period. The purpose of this test was to evaluate any effect of the time periods between valve closures on closing time. The closing time was.3.6 seconds which included seconds for Solenoid valve action. The results were fully satisfactory and showed no sticking of any parts after the 38 day standing tim *

It was determined that the hydraulic system jockey pump actua-tion is now within a 7 to 12 day period. This is a large improvement over the original system's 2 to 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> actuation perio The inspector was informed that the separate prototype valve to be used in testing required by the license condition is not as yet assemble .4 Present Concerns

The observed increased leak rate in those valves with the new Latty Tex seat spool packing material suggests a potential problem area. This packing has to seal to enable effective seatin The effects of flow and temperature on valve performance are presently unknown. The planned prototype testing will be

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relied upon to provide an assessment of flow and temperature effect The concern expressed in the prior inspection, that the ef-fectiveness of the current fixes has not been fully verified, still exist The ball scoring problem is still an issu The serviceability of the hydraulic actuator is still an issu The Office of Nuclear Reactor Regulation has overall responsibility for the licensing of the facility and determination of the technical acceptability of the MSIV's with appropriate input from the Regional staf .5 Resolution of Prior Inspection Concerns 2. Bronze Thrust Washer - The SWEC Materials Engineer provided details of the N&D C94743 which authorized the MSIV thrust washer material change from the 300 series stainless steel to bronze to eliminate the previously ob-served galling problem. The inspector determined that the new thrust washer final material selection was UNS C22000 Bronze Allo .

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-* 5 The inspector verified that the downstream piping contains considerable copper bearing material. Dwg 20,800-002-026 Sheet I and GE weld material instructions define the pipe material as copper bearing. Also, procurement specifica-tion P111P shows the condenser peripheral tubes to be 70-30 copper nickel and the remainder of tubes to be admiralty meta The verification of the downstream copper bearing material resolved the prior inspection concern of the new bronze MSIV thrust washe . SOV Safety Category - Inspection Report No. 50-410/86-53 raised a question regarding the classification of the solenoid operated valves and hydraulic cylinder associated with the redesigned MSIV actuator and the licensee had indicated that details of the classification would be pro-vided for the inspectors revie To resolve the safety category concern, the inspector was provided: the SWEC Qualification Summary Report for the s NMP-2 Modified MSIV Actuator (Target Rock 2" SOV) dated 10-25-86, the SWEC evaluation of the Target Rock SOVs for suitability in the continuously energized position, the Target Rock Design Report 2252C for Category 1 SOVs, and information on the addition of a spacer in the SOV to increase the spring preload to shorten the valve response time. The environmental qualification analytical calcula-tion for the graphite filled teflon was also provided to the inspecto Finally, information concerning the testing of SOVs in which the "0"-ring sticking problem was identi-fied was provided to the inspector. This problem neces-sitated the change to a graphite filled teflon ring with the EP ring behind i From the review of the above information the 2" SOVs while not ASME stamped were shown to be qualified Category 1, Class IE safety equipment which resolved the prior inspection concer .6 Conclusions The licensee is continuing to work toward resolving the problems with the new ball type MSIVs and toward satisfying existing license conditions. Modifications to the hydraulic system have been quickly addressed by the licensee. The licensee also recognizes the importance of the seat spool packin Post preoperational leak rate tests, confirmatory leak tests, and Technical Specification required surveillances will provide conti-

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nuous monitoring for potential valve degradation related to the con-cerns expressed in Paragraph In addition, the planned prototype testing program will provide data on the affects of temperature and flow on the valves. Failure of any of these tests will require valve disassembly and repair and an assessment of the failure mechanis The MSIVs are critical safety equipment and the current open items:

(0 pen) 86-00-20 MSIV leakage problems, (0 pen) 86-00-19 MSIV closure time problems, and (0 pen) 86-00-18 MSIV roller bearing problems will remain open until preoperational and confirmatory leak tests and valve performance testing during the early operational phase shows the valves are performing satisfactoril The details of this report update the three open items listed abov .0 Exit Meeting The inspector met with the licensee's representative (identified in paragraph 1.0) at the conclusion of the inspection on December 5, 1986, to summarize the findings of this inspection. The NRC Resident Inspectors, W. Cook and W. Schmidt, were also in attendanc During this inspection, the inspector did not provide any written material to the license I

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