IR 05000412/1993025

Insp Rept 50-412/93-25 on 931018-22.Violations Noted. Major Areas Inspected:Adequacy of Repair & Maintenance of Safety Class 1 Valves,Including follow-up of Auxiliary Feedwater (AFW) Water Hammer Issue

ML20058H308
Person / Time
Site:	Beaver Valley
Issue date:	11/29/1993
From:	Carrasco J, Modes M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20058H286	List: IR 05000412/1993025 ML20058H277 ML20058H297
References
50-412-93-25, NUDOCS 9312130045
Download: ML20058H308 (9)

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U.S. NUCLEAR REGULATORY COMMISSION REGION 1

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REPORT / DOCKET NOS. 50-412/93-25 LICENSE N NPF-73

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LICENSEE: Duquesne Light Company Post Office Box 4 Shippingport, Pennsylvania 15077 FACILITY NAME: Beaver Valley Unit 2 i

INSPECTION AT: Shippingport, PA INSPECTION DATES: October 18-22, 1993

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A INSPECTOR: 8 f/ //~28'/3 '

Josdph-Carrasco, Reactor Engineer Date Materials Section, EB, DRS i

APPROVED BY: ~

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Michael C. Modes, Chief bate ~

Materials Section, EB, DRS

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9312130045 931206 PDR ADOCK 05000412 G PDR

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Areas Inspected: A safety inspection was conducted to determine the adequacy of the repair and maintenance of safety Class i valves, including a follow-up of the auxiliary feedwater 1

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(AFW) water hammer issu Results Based on the review and discussions with engineering, the inspector concluded that approvals for the repair of valve body-to-bonnet leaks using clamps and cap nuts, supplemented by injections of scalant material were in-place. However, it was noted that the licensee engineering heavily relied on valve vendor recommendations presented by the valve vendor and leak repair contractor. These recommendations, such as number of injections ,

applied during repairs were accepted with limited reviews of the material, material properties and material strength limitation One violation was identified regarding (1) a failure to implement the torque value established

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in the repair procedure and (2) the failure to establish quantitative or qualitative acceptance criteria for the applied torque related to the nuts of the body-to-bonnet studs of the air i

operated valv ,

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DETAILS PURPOSE AND SCOPE The purpose of this inspection was to review and assess the licensee's leak repair process for j

safety Class 1 valves. This inspection also reviewed licensee actions to address the water '

hammer event documented in Inspection Report No. 50-412/93-0 .0 BACKGROUND The process of injection scaling of leaks in pressurized pipe and components, such as valves, flanges, and 6ttings is used in nuclear power plants to temporarily repair leaks during operation. This inspection was performed to insure that adequate controls and engineering oversight are provided for safety-related application l REVIEW OF TIIE GENERAL LEAK REPAIR PROCEDURE ,

The inspector reviewed the licensee's Repair Procedure No.1/2 CMP-75-LEAK REPAIR-lM J

which provides instructions for utilizing an approved vendor leak repair procedure. The inspector verified that critical attributes were delineated in this general leak repair procedur Some of these attributes are the quality control (QC) review of the vendor procedure including the insertion of holdpoints, the review and approval of the vendor's procedure by ,

the On-site Committee (OSC), and the notification of the Authorized Nuclear Inspector (ANI)

if repair involves drilling into the valve pressure boundar The inspector concluded that this general repair procedure provides adequate and suf6cient guidelines to the licensee for reviewing, controlling and approving the vendor prepared detailed repair procedure unique to a specific repai .0 REVIEW OF REPAIR PACKAGES The inspector reviewed and discussed engineering approvals for repairs. The review was focussed on valve body-to-bonnet leaks using clamps and cap nuts, supplemented by injections of scalant materia McNenance Work Request (MWR No. 896238)

The inspector reviewed MWR No. 896238 for completeness and compliance with established requirements. In addition to the package review, the inspector interviewed maintenance personnel and the responsible engineer for the maintenance work request MWR No. 896238 which is a leak repair for a 16" swing check valve 2FWS-30 in the auxiliary feedwater system inside containment. A synopsis (see attachment 1) is attached to indicate the length of time it took the licensee to repair this valve. Based on this synopsis, the inspector noted that a clamp was used and that the actual repair started on August 14, 1989, and ended October 11, 199 .

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t According to the licensee's maintenance engineers, the sealant.was injected eight (8) time During the fourth injection, pressure was reduced to 2200 psi plus static gun pressure, as a precaution against overstressing the studs. This was confirmed by the responsible engineer who stated that the vendor authorized up to 4000 psi without any analysis to support the recommendation. In this case, the vendor disregarded the material limitations. According to the responsible engineer, the vendor stated that they never had a failure and they can inject up to the material yield of the stu On March 1,196, leaks were detected on the capnuts. This time the capnuts were reinstalled, after cleaning, to a torque equal to 560 ft-lbs. On April 19, 1990, all stud nuts were replaced with capnuts (total of 16). At this point the capnuts were injected for a third time. The inspector verified that a safety analysis, per 10 CFR 50.59, was performed to ass"s the use of the capnuts. The inspector noted that the temporary modification and safety analysis were approved on January 22,199 On August 8,1990, ultrasonic testing (UT) was performed on the 16 bonr.et studs and it was determined that no stud degradation existed. The responsible engineer stated that he was prompted to UT the studs to assure the integrity of the stud Conclusion Based on the review, and discussions with engineering, the inspector concluded that approvals for the repair of valve body-to-bonnet leaks using clamps and cap nuts, supplemented by injections of sealant material were in place. However, it was noted that the licensee engineering relied heavily on recommendations presented by the valve vendor and leak repair contractor. These recommendations, such as the number ofinjections applied during repairs, were accepted with limited reviews of the material, material properties and strength limitations of the materia .2 Maintenance Work Request (MWR No. 004452)

A review of MWR No. 004452 was also performed to verify adherence to established requirements and engineering practices. In addition to the MWR package review, the inspector interviewed maintenance personnel and the responsible engineer for the

- maintenance work request (MWR No. 004452). This was a leak repair for the feed header check valve 2FWS-2816" swing check valve in the auxiliary feedwater syste Sealant was injected into two capnuts at a pressure of 2400 psi and torqued to 83 ft-Ibs. The licensee stated that this value was obtained as a result of a telephone conversation. At this point the inspector expressed a concern regarding the safety Class 1 data and its documentation. The licensee further researched their documentation and at the exit meeting they presented a more formal transmittal documenting the recommended torque valu .

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According to EM No. 102124, a gap between the bearing cover and valve body was not wide enough to wrap with wire. Therefore, peening was proposed to cover the gaps. "agineering !

approved the use of limited peening. Later during the inspection, the licensee stated that no peening was neede Conclusion

Although the licensee provided the supporting documentation to substantiate the torque values ;

for the capnuts, and additional information was also provided to clarify that peening was not used for the leak repai .3 Maintenance Work Request (MWR No. 003370)

l In addition to the package review, the inspector interviewed maintenance personnel and the ;

responsible engineer for the maintenance work request MWR No. 003370. This is a ]

maintenance repair for air operated valve (No. 2CHS-LCV460B) in the reactor containment building. The function of this valve was described as a regenerative heat exchanger letdown inlet valv On April 5,1992, the torque value (340 ft-lbs) prescribed in the repair procedure was not used. Instead, body nuts were tightened until the body-to-bonnet cap was metal to metal within 0.002 inch. Measures were not established, such as quantitative or qualitative acceptance criteria for determining the applied torque to the nuts of the studs that connects the body ar.d bonnet of the air operated valve 2CHS-LCV460 The description of the failure in the package indicated that a body to bonnet leak was discovered during a containment entry which was attributed to relaxation of torque or insufficient torque applied to bonnet bolting. Since the design configuration of the valve and surrounding obstructions prevent the proper use of a torque wrench; this situation was !

resolved by replacing the bonnet gasket. In addition, Procedure No. 2 CMP-75-FISHER l VLV-14, Issue 4, Revision 0, was changed to tighten bonnet bolting until the gasket crushe ;

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Conclusion j One violation was identified regarding (1) a failure to implement the torque value established in the repair procedure and (2) the failure to establish quantitative or qualitative acceptance criteria for the applied torque related to the nuts of the body-to-bonnet studs of the air-operated valve (VIO 412/93-25-01). l

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6 FOLLOW-UP ON AUXILIARY FEED WATER (AFW) WATER HAMMER

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(INSPECTION REPORT NO. 50-412/93-06) 1 Beaver Valley, Unit 2, auxiliary feed water k>op 'C' has experienced steam pocket formation due to check valve leakage. Subsequent water hammer occurred due to veid collapse under unthrottled auxiliary feed flow following pump startu The licensee's corrective action included replacement of the existing 4" swing disc type auxiliary feed water check valves with nozzle check valves. Through the use of the positive

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closure nozzle check valves which are bubble tight valves, void formation and hence water hammer has been mitigate ,

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The specific valves replaced include the inside containment check valves adjacent to the main feed water piping,2FWE-99,100 and 101. In addition, check valves outside containment in the Safeguards building were also replaced. These valves are 2FWE-42A & B,43A & B,

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and 44A & ?

i Valve characteristics claimed by the manufacturer include tight shut off with leakage requirements that are much more restrictive than conventional swing disc check valve .0 MANAGEMENT MEETINGS Licensee management was informed of the scope and purpose of the inspection at the

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i beginning of the inspection. The findings of the inspection were discussed with the licensee management at the October 22,1993, exit meeting. See Attachment 2 for attendanc i

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ATTACIIMENT 1 t e

Synopsis of Engineering Memorandunts for 2FWS-30 I involving Irak Repair i EM 64662 Request for NED concurrence to install Leak August 14, 1989 Repair clamp and inject with sealing compoun Re inject with 2XX (High Viscosity) and 2W (Low October 10, 1989 EM 64708 viscosity) per Procedure NP-2129 EM 64714 Rework Leak Repair Clam October 25,1989 (Remove clamp and sealant. Check torque of bonnet bolting. Reinstall clamp and inject with scalant 2X and 2W. Scalant pressure to be 2200 PSI plus station pressure. Clamp to be rotated on reinstallatio j EM 64723 Replace clamp tubing and tack weld tubing to clamp at October 27,1989 2" intervals. Re inject per Procedure NP- ,

2129 with 18X sealant. Sealant pressure to be limited to 2200 PSI plus static gun pressur EM 65075 Install capnuts on every other stud. (eight of December 21,1989 sixteen). Use Procedure SNP-203. Capnut torque to be limited to 500 ft-lb EM 64748 Removed clamp and after measuring clamp, November 11,1989 decided to fabricate a new clamp. Install new clamp with Procedure NP-2114. Approved i

scalants are 2X, 2W,18X, and G-Fiber. Sealant pressure to be limited to 2000 PSI plus static gun pressur EM 65119 Remove leaking capnut. Clean capnut by drilling March 1,1990 out the old sealant material. Install capnut and {

torque to 560 ft-lbs. (+/-10 ft-lbs.) Sealant  ;

injection is 3596 PSI plus static gun pressur EM 65143 Remove clamp. Grind out existing scalant from March 20,1990 ;

between valve body, bonnet and studs. Install ,

stainless steel wire wrap. Install eight new ASME 111 capnuts and inject capnuts with mixture of "X-  !

36" and fine grain "G-Fiber". Use Procedure NP- -

2112. Capnut torque shall be 560 ft-lbs (+10-10 ft-lbs). Sealant injection pressure shall not exceed 3590 PSI plus static gun pressure. Scalant usage should be 1 gallon for capnuts and 23 cubic inches for clam EM 65153 Remove capnuts and install in the locations with April 12,1990 studs. Sealant injection pressure shall be 3596 _;

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plus static gun pressur :

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Attachment 1 2 ,

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EM 65161 Replace all studs with capnuts (total of 16). April 19,1990 r

Capnuts are all ASME III. Capnut torque and *

sealant injection pressure remain the sam EM 65241 Remove capnuts one at a time to vent clam August 7,1990

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Reinstall capnuts and torque to 560 ft-lbs. Inject capnuts at 3000 PSI plus static gun pressure. Use ,

sealant 2X and 2W along with G-Fiber EM 65242 Revised EM 65241 to use scalant X36A and B August 7,1990 EM 65604 Performed a UT on bonnet studs and determined August 8,1990 that no stud degradation existed. Removed installed clamp and wire wrap from between the l

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body to bonnet joint. Clean the joint are Replace wire wrap and re-clamp using either clamped cable or metal banding and clamp or original clamp. Re inject sealant through existing cap nuts. Sealant injection pressure and capnut torque to remain consistent with past  ;

performanc ,

EM 76295 Engineering concurrence to remove and clean August 16,1990  ;

capnuts one at a time, Re torque to be 560 FT-lbs

(+/- 10 ft-lbs)  :

EM 65260 Install a tenth capnut (ASME Section VII) now August 22,1990 ,

installed are seven Section Ill and three Section  ;

VIII capnut EM 65261 Re inject capnuts using 18X sealant with 2W August 27,1990 liquid. Seal injection pressure limited to 3000 PSI plus static gun pressur EM 65684 Request to repair steam cut across bonnet gasket October 1,1990 seating surface. Cut is approximately 1-1/2" wide by app. 0.030" deep

EM 65715 Request to review machining of top (or cover) cnd October 11, 1990 i

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of valve to clean up gasket seating area. Area was I

damaged when gasket seating area was welded upon during removal of a liner indication on the valve bod I

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ATTAClIMENT 2 PERSONS CONTACTED Duauesne Licht Company r

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• J. D. Sieber, Senior Vice-President - Nuclear Power Division '

• D. Spoerry, Division Vice-President of Nuclear Operations

• G. Thomas, Division Vice-President of Nuclear Services

• M. Siegel, Manager Nuclear Engineering Division (NED)

• N. R. Tonet, Manager Nuclear Safety

• R. L. Hansen, Director NED B. Zini, Supervisor NED M. Testa, Senior Engineer  :

• T. Noonan, General Manager, Operations

• B. F. Sepelak, Licensing Engineer

• F. J. Lipchick, Senior Licensing Engineer

• K. Grada, Manager QSU

• J. Baumler, Director of Audit and Sur U.S. Nuclear Regulatory Commission

• L. Rossbach, Senior Resident Inspector

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Asterisk (*) denotes those present at the exit meetin ,

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