IR 05000410/1987003

Insp Rept 50-410/87-03 on 870112-28.No Violations Noted. Major Areas Inspected:Licensee Activities Re MSIV Problems

ML20204F398
Person / Time
Site:	Nine Mile Point
Issue date:	03/06/1987
From:	Gregg H, Strosnider J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20204F311	List: IR 05000410/1987003 ML20204F305
References
50-410-87-03, 50-410-87-3, NUDOCS 8703260188
Download: ML20204F398 (9)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

Report N /87-03 Docket N License No. NPF-54 Priority --

Category B Licensee: Niagara Mohawk Power Corporation T06 0 Erie Boulevard West Syracuse, New York 13202 Facility Name: Nine Mile Point Nuclear Power Station, Unit 2 Inspection At: Scriba, New York Inspection Conducted: January 12-28, 1987 Inspector # LW H. I. Gregg, Ledd(~ Neactor Engineer S! / ddte f ~/

Approved by: ,

. Strosnt3er, 4 Chief, Materials J[d[87

. date and Processes Section, Engineering Branch, DRS

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Inspection Summary: Ins conducted both on site aiid in office (Report % pf'ction on Janua y__12-28, 1987

. 50-4T67F61).

Areas Inspected: This inspection was a routine unannounced followup inspection F licensee's activities related to Main Steam Isolation Valve (MSIV) problem The inspector reviewed the details of the licensee's type "C" leak test that one valve failed, the subsequent internal examination of four valves which revealed scoring of the seats and balls, additional special testing that was performed, and the final acceptable type "C" leak test results of the four reassembled valve Observations were made of scored valve components and discussions were held with cognizant licensee personnel regarding the continued scoring of the seats and balls. Additionally, the licensee's submittal of January 14, 1987 which presented the basis for proposed operation with the ball type MSIVs was reviewe Results: No violations were identified, however, based on the latest disassembly

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and examination of the MSIVs by the licensee, the scoring of the seats and balls thought to be solved by the respringing of the seats, has not been fully resolve PDR ADOCK 05000410 0 PDR

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DETAILS 1.0 Persons Contacted t 1.1 Niagara Mohawk Power Corporation (NMpC)  ;

• G. Afflerbach, Work Control Manager

• C. Beckham, Quality Assurance Manager J. Brady, Quality Assurance Engineer

• K. Buckley, NC and V Technician J. Bunyan, Lead Electrical Engineer

• R. Cohen, Manager Site Services W. Hansen, Manager Nuclear QA Operations E. Klein, Site Licensing Engineer A. Lepore, Quality Assurance Engineer

• A. Pinter, Site Licensing Engineer

• C D. Terry, Manager Nuclear Engineer

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1.2 Stone & Webster Engineering Corporation (SWEC)

• T. Arrington, Project Quality Assurance Manager

• C, Crocker, Project Engineer

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J. De Bonis, Prototype Test Coordinator l

• J. Gallagher, Lead Licensing /EA Engineer i

• D Koehl, Work Control Supervisor 1.3 Central Hudson Gas and Electric Corporation

• C, Millspaugh, Site Representative i

1.4 New York State Electric and Gas Corporation

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• P. Mc Ewan, Site Representative 1.5 Rochester Gas and Electric Corporation J. Hutton, Manager MSIV Long Term Program

• Larizza, Site Representative l 1.6 Public Service _ Commission l

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

• Cook, Senior Resident Inspector

• Denotes those present at exit meetin t

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2.0 Purpose and Scope of MSIV Inspection '

The purpose of this inspection was to obtain an update on activities related to the MSIVs (since the last inspection of December 21, 1986 (IR 86-67)) and riview the licensee's recent findings of more scoring of the MSIVs balls. The review covered the special testing and extended cycle testing perforned on one valve, the preoperational test closure times, and the current tyoe "C" leak test results of all 8 MSIV Additionally, the Itcensee's submittal of January 16, 1986, which presented the licensee's bases for continued operation with the ball type MS!Vs was reviewe .0 Testing Chronology and Results ..

The following information was obtained from the licensee. The type "C" leak test conducted on 12/21/86 following preoperational valve testing resulted in valve 6B exceeding the 6 SCFH acceptance criterion. The valve was disassembled and some scoring of the ball was found. The bonnets were removed from valves 6C, 60 and 70 and some score marks were observed on the balls. (Valve 70 was subsequently disassembled). This current scoring of the balls and slight scratches on the seat were less severe than previously experienced (see Inspection Report 86-67). Due to findings of additional scoring, the licensee instituted further testin During the inspection a tabulation of the testing chronology and results (Table 3.1) was prepared by the inspector and is included as the last two pages of this report. The details of these tests are described in the following paragraph .0 Special Ball Testing Two tests were performed with special balls and reduced seat packing spring loads. The first test was performed with a ball that had a Haynes 25 overlay, no tungsten carbide coating, and seat load reduced from 6900 lbs, to approximately 2000 lbs. This test resulted in leak test failure af ter 5 cycles. Extremely heavy scoring of the ball and seats occurre The second test was conducted with a tungsten carbide coated ball, no Haynes 25 overlay, and seat load reduced to approximately 4140 lbs. This test also resulted in leak test failure af ter several cycles. Heavy scoring of the ball and seats occurred - but not to the extent of the first tes .0 Special Extendedj ycle Testing The slightly scored ball and seats from valve 68, considered by the Itcensee to be the worst of the 4 newly found scored valves, was placed in valve 70. Special extended cycle testing with the ball wetted and dry were run and leak tests were monitored throughout the testing. . .

After 72 cycles (36 Full and 36 Partial) with the wetted ball, the through the valve testing (TTV) leak rate was 9.3 SCFH. This was an increase from 5.5 SCFH measured at the beginning of the extended cycle testing. The testing was continued with a dry ball and the TTV leak rate after 32 more cycles (16 Full and 16 Partial) was 16.9 SCFH. Between the seat (BTS)

leak testing was also performed. The BTS leakage was 2-1/2 to 4 times higher than TT The inspector observed the ball and seats of this valv The ball was scored in the top and bottom areas and in several locations through the tungsten carbide coating into the Haynes 25 underlay. On one side the scoring was approximately 3/8" wide and traversed from the open position into the seating closed position (with very light scratch marks in the closed position location). On the other side the scoring was less sever The seats had scrape marks on the top and bottom of the seat face and sharp edges in several location There was some Stellite removal (galling type depressions) at the top and bottom seat locations (at a midpoint of the seat).

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The inspector's evaluation of this ball was that while the scoring was unsatisfactory, it was not as severe as the original scoring with the original uniform seat springing. The seats, while not badly scored, had Stellite removal (1/8" wide x 1/4" long areas) in several locations. It was the first time this was observe .0 Final Type "C" Leak _Testine

The final leak testing of valve 70 assembled with its old ball and seats l (which had Itght scratches) was observed. The measured leak rate was 5.729 SCFH. The final leak test results for all 8 MSIVs was reviewed and all valves were within the 6 SCFH leakage criterion for BTS testin .0 Closure Time Tests The inspector reviewed the preoperational test MSIV closure time data and determined they were between 4.12 and 4.66 sec. which is within the 3 to 5 seconds required by the technical specification .0 Status of MSIV_ Construction _ Deficiency Reports LCORs)

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Three separate construction deficiency reports (CORs) exist regarding the MSIVs and a condition to the Nine Mile Point 2 Itcense requires that these CORs be resolved prior to the reactor being made critical. The three CORs are:

• 86-00-20 MSIV leakage problem * 86-00-19 MSIV closure time problems, and  ;

• 86-00-18 MSIV cracked roller bearing problem l Prior Region ! inspection reports 50-410/86-67 and 86-53 provided update information involving these CORs. Based on the inspections to date,

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-5 closecut of one of the CDR issues can be made and specific update information can be provided for the other two as follows:

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, (Closed) CDR 86-00-18 MSIV Roller Bearing Problem

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Previous inspections (IR 86-67, and IR 86-53) of MSIV related activities included review of the original mechanical latch actuator problems and the l

subsequent changeover to an all hydraulic actuator. With the change to an all hydraulic actuator, the entire mechanical latching mechanism and

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the roller mechanism involved with.this CDR have been removed from all 8 MSIVs. The inspector verified removal of the latch assembl This item is close '

(0 pen) CDR 86-00-19 MSIVClosureTimeproblems The recent MSIV inspections have reviewed the evolution of the mechanical and piping aspects of the hydraulic actuator. This included the following revisions to > a actuation system. The licensee indicated that the Target Rock solenoid operated valves were modified with a spacer to increase the spring preload thereby shortening the valve response time. Also, a

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graphited teflon seal ring with an EP ring behind it was added to eliminate the disc sticking problem. The piping system was modified to include a jockey pump, a new hydraulic cylinder, a different check valve and a different relief valve. A 7/8" external orifice was placed in the piping at the rod end of the cylinder to control the closure time within the required 3 to 5 second The preoserational test data closing times were reviewed and all 8 valves closed within 4.12 and 4.66 seconds (see tabulation). Currently, there is an electrical system change involving valve closure logic. Closing time testing will be performed after the changes are made to verify that the 3-5 sece,d closing time is maintaine While tie i.echanical and piping modifications appear to acceptably address the clo iq tine, there could be some electrical aspect or interaction with the mechanical components that wt11 relate to closing time due to the intended logic changes. Further testing and verification of acceptable l closing time will be reviewed on a forthcoming electrical inspectio This CDR wt11 remain open until the logic aspects and final closing time results are fully evaluated, and it is concluded closure time problems are eliminate {0 pen)CDR 86-00-20 MSIV Leakage Problems This inspection and the two previous inspections referenced above address the MSIV lealage problems. This CDR is being held open pending verifi-cation of the adequacy of the current fixes, more test data and NRC review and verification of the operational adequacy of these new ball type  ;

valve l

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The licensee submitted a report dated October 20, 1986 after they successfully tested one valve. The report concluded that the ball and seat scoring problem was resolved and would not occur within the first operating cycl Recent events as described in this report have shown that the ball and seat scoring problem has not been fully resolved, therefore, the details of the licensee's October 20, 1986 submittal are not applicable. The licensee has reviewed the current status and by letter dated January 14, 1987 has submitted a safety analysis for operation of the plant with the ball type MSIVs. The submittal states that based on the special extended cycle testing discussed in Section 5.0 of this report, the anticipated leak rate through the valves would be limited to an acceptable level for the number of valve cycles anticipated during the first cycle of reactor operatio While this inspection verified that all 8 MSIVs meet their 6 SCFH leak rate requirement, the effects of flow, temperature, and pressure on valve performance are still not know The licensee is committed to leak test the valves following the warranty run. This confirmatory leak test and the planned prototype testing will provide further dat This CDR is being kept open pending NRC detailed evaluation of the licensee's latest submittal of January 14, 1987, and forthcoming prototype test result .0 Conclusions

• The original problem of scoring of the ball and seat, due to seat instability and resulting high concentrated loads as the large port is eclipsed, has not been fully resolve The spring offsit was beneficial, however, the basic original problem still exist * The extended cycle test of 6B internals in valve 70 provides some basis for first operating cycle use, but the data must have careful review as there are no actual test results with flow, temperature and pressur * Prototype testing will provide additional data to demonstrate operability

• The current fixes aren't the final fixes if the valve is to perform to the vendor's original specificatio Major redesign of the internals may be necessar * Currently all 8 installed MSIVs meet their 6 SCFH leakage requiremen * The warranty run leakage test and prototype tests will provide an intermediate review of the effects of operating condition If leakage is excessive the valves will need repai . .-_ _ __ ___--__ -_-_ _ -_ _-_ __

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Subsequent to the writing of this report, NRC was notified on February 7, 1987, of gross leakage failure after the prototype startup test sequenc The problem was identified as leaking through the seat spool packing due to large clearances after cooldown. This was after the first steam test (temperature, pressure, steam flow) of these valves.

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Maintaining a seat spool packing seal is critical to the effective operation of this valve. If this seal is not maintained an alternate leak path with leakage far in excess of the seat leakage can be create This issue must be resolved before CDR No. 86-00-20 can be close .0 Exit Meeting

, The inspector met with the licensee's repretentative (identified in para-graph 1.0) at the conclusion of the on si .e inspection on January 16, 1986, to summart:e the findings of this inspectio The NRC Senior

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Resident Inspector, W. Cook, was also in attendanc .

t During this inspection, the inspector did not provide any written material to the licensee, i

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