B14180, Forwards Rev to 911017 Requests for Relief from Second 10-yr Inservice Insp Testing Program.Encl Describes Alternate Testing for Centrifugal Charging Pump Measurements & Vibration Monitoring

Forwards Rev to 911017 Requests for Relief from Second 10-yr Inservice Insp Testing Program.Encl Describes Alternate Testing for Centrifugal Charging Pump Measurements & Vibration Monitoring

ML20102A249
Person / Time
Site:	Millstone
Issue date:	07/15/1992
From:	Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B14180, NUDOCS 9207240150
Download: ML20102A249 (6)

Text

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, _ . . . ~ . , .s wmono. coma mrumm-ono acamsaan July 15, 1992 Docket No. S Elh IlL41A2 Re: Inservice Inspection Program 10CfR50.55a(g)

U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Millstone Nuclear Power Station, Unit No. 2 Second Ten-Year Inservice Inspection Testing Program Revision to Previous Relie.f_Re_q m t The purpose of this lett dated October 17,1991,(g is to revise in which certain Northeast portions Nuclear EnergyofCompany a previous letter (NNECO) responded to the NRC Staff's request for additional information regarding the second ten-year inservice test (IST) program at Millstone Unit No. 2.

DEIGmLO.d In a letter dated October 30, 1987,'2) supplemented by letter dated August 26, 1988,* NNECO submitted the second ten-year interval IST Program for Millstone Unit No. 2. These letters also requested relief from testing requirements that were determined to be impractical or would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety, and proposed alternatives to provide an acceptable level of quality and safety.

The NRC Staff reviewed and subsequently provided NNECO with the Safety Evaluation

! (SE), Technical Evaluation Report (TER), and associated findings in a letter l

(1) E. J. Hroczka letter to U.S. Nuclear Regulatory Commission, " Millstone Nuclear Power Station, Unit No. 2 Response to Request fer f.dditional Information Second 10-Year In Service Inspection Testing Program," dated October 17, 1991.

(2) E. J. Hroczka letter to U.S. Nuclear Regulatory Commission, " Millstone Nuclear Power Station, Unit No. 2 Inservice Inspection Testing Program,"

dated October 30, 1987.

(3) E. J. Mroczka letter to U.S. Nuclear Regulatory Commission, " Millstone Nuclear Power Station, Unit No. 2 Inservice inspection Testing Program (TAC #59265)," dated August 26, 1988.

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U..S. Nuclear Regulatory Commission

• B14180/Page 2 July 15, 1992 dated July 19, 1990.") Relief from certain testing requirements was granted with specified conditiona as provided in Table 1 of the SE. The IST Program was also found to be acceptable for implementation, provided the omissions and inconsistencies identified in the SE and in Appendix C of the 1ER were addressed within six months of the receipt of the SE.

In a letter dated January 28, 1991,0) NNEC0 provided the additional information to the NRC Staff, as requested. 1his letter supplemented and clarified infonnation that had been identified in the Staff's SE and contractor's TER.

Later, in a letter dated June 18, 1991,") the NRC Staff requested additional '

information. Thi provided as requested in NNECO's letter dated August 9, 1991.'3)information Changes to ;he was IST Program, which superseded certain information previously provided, were specifically identified.

During a telephone conference between NRC Staff and NNECO personnel on August 19, 1991, the Staff requested additional information to clarify certain relief requegt,s which had been submitted previously. In a letter dated October 17, 1991, NNECO provided the clarifying information as requested.

Attachment 1 to this letter contains a revision to-our relief request IWP 1, previously submitted in the October 17, 1991, letter. This revision to relief request IWP-1 deletes all reference to special consideration or expanded vibration limits for IST of the service water pumps and supersedes the IWP 1 (4) J. F. Stolz letter to E. J. Mroczka, "Second Ten Year Inservice Testing Program and the Granting of Relief From Testing Requirements Determincd to be Impractical for Millstone, Unit 2 (TAC 75977)," dated July 19, 1990.

(5) E. J. Hroczka letter to U.S. Nuclear Regulatory Commission, " Millstone Nuclear Power Station, Unit No. 2, Second Ten-Year Inservice Inspection Testing Program Response to NRC Staff Request _(TAC 75977)," dated J:nuary 28, 1991.

(6) G. S. Vissing letter to E. J. Mroczka, " Millstone Unit 2, Request for Additional Information Regarding Relief Concerning Second Ten-Year Inservice Testing Program (TAC No._79688)," dated June 18, 1991.

(7) E. J. Hroczka letter to U.S. Nuclear Regulatory Commission, " Millstone Nuclear Power Station, Unit No. 2, Response to Request for Additional Information, Second 10-Year Inservice Inspection Testing Program," dated August-9, 1991.

(8) E. J. Mroczka letter to U.S. Nuclear Regulatory Commission, Millstone Nuclear Power Station, Unit No. 2 Response to Request for Additional Information Second 10-Year Inservice Testi,g Program," dated October 17, l

1991.

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l U.S.' Nuclear Regulatory Commission

• B14180/Page 3 July 15, 1992 information previously provided in footnotes 1, 2, 3, and 6. NNECO's review of service water pump operating history over the past two years indicates that the vibration limits, applicable to other similar rotating equipmert, can now be effectively implemented for the service water pumps, further, the service water pump casing and motor stand assemblies are being considered for replacement over the next several years. If this replacement occurs, improved designed casing and motor stand assemblies will likely be installed which are designed to reduce the motor response to small changes in balance. Thus, the potential for reduction in availability, caused by insignificant changes in pump motor balance, is reduced. This relief request revision is conristent with the guidelines of ASME Operating and Maintenance Standard OH 6.

We trust the submittal of this information will provide the NRC Staff with the ,

information to complete their review of NNECO's request for relief from certain ASME Code testing requirements. NNEC0 respectfully requests consideration toward issuance of the SE at your earliest convenience, but no later than August 14, 1992.

Should you have any further questions relating to this issue, please contact my staff.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY

% < f { $L. U J. F. Opekh Executive Vice President cc: T. T. Martin, Region 1 Administrator G. S. Vissing, NRC Project Manager, Millstone Unit No. 2 P. D. Swetland, Senior Resident inspector, Millstone Unit Nos. 1, 2, & 3 I

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Docket No, '- d 9

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Attachment 1 Millstone Nuclear Power Station, Unit No. 2 Second Ten Year Inservice Inspection Testing Program Revision to Previous Relief Request IWP-1 I

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July 1992

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Relief Request No. RR-lWP-1 (llevised 2-21-92)

Ceniponents Affected All safety-related pumps Code Reference Article IWP-4510 Article IWP-3210, Table IWP 3100-2 (Vibration)

Cude Test Requirement Measure during each in-service test, displacement vibration amplitude (mils) 11 asis for Ilditi Experience has shown that measurement of overall vibration amplitude in mils ducs not provide the desired early warning of pump degradation. Vibration amplitude is adequate for measuring unbalance, misalignment, and other low frequency failure modes, it does not give early warning of bearing degradation since the magnitude of higher frequency vibrations created by such degradation is 10 to 1,000 times lower than the normal pump movements. Experience at Northeast Utilities has shown that monitoring pump vibration velocity (in/sec) provides earlier warning of pump degradation. Collection and review of vibration " signatures" (plots of vibration velocity vs. frequency) over a range from slightly below running frequency to several times running frequency provides optimal early warning of pump degradation.

Absolute maximum limits are set for each pump.

Altern;ite Testing For centrifugal pumps, measurements will be taken in a plane approximately perpendicular to the rotating shaft in two orthogonal directions on each accessible bearing housing and one measurement will be taken in the axial direction on each thrust bearing housing.

For reciprocating pumps, the location will be on a bearing housing of the crankshaft, approximately perpendicular to both the crankshaft and the line of plunger travel.

On vertical line i, haft pumps, measurements will be taken on the upper motor bearing housing in three orthogonal directions including one axial direction Vibration will be monitored during each in-service test using equipment which collects vibration velocity signatures over a range from less than one-third running speed to at least eight l times running speed.

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Overall vibration velocity (in/sec Peak) will be compared to the

. following acceptance criteria:

1. Acceptable Range - less than 2.5 times Reference Velocity and less than 0.325 inches per second (Peak) l

2. Alert Range - 2.5 to 5 times Reference Velocity or greater than 0.325 inches per second (Peak)

3. Required Action Range - Greater than 5 times Reference Velocity or greater than 0.70 inches per second (Peak).

Reference Velocity shall be the average overall velocity determined during an in-service test at reference conditions when the pump is known to be operating acceptably, in additien to the above quantitative analysis of overall vibration levels vibration signatures will be reviewed at least quarterly to identify potential bearing degradation or other developing faults.

When potential faults are identified, action, as required for a pump in the Alert Range of vibration will be initiated.

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