ML20205J069

Forwards Response to NRC 990129 RAI Re GL 96-05, Periodic Verification of Design-Basis Capability of Safety-Related Movs

ML20205J069
Person / Time
Site:	Calvert Cliffs
Issue date:	04/02/1999
From:	Cruse C BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-05, GL-96-5, TAC-M97028, TAC-M97029, NUDOCS 9904090158
Download: ML20205J069 (7)

Text

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CHAOLES II. CRUSE Baltimore Gas and Electric Company V ce President Calvert Cliffs Nuclear Power Plant

. . Nuclear Energy 1650 Calvert Cliffs Parkway

! usby, Maryland 2%57 410 495-4455 April 2,1999 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Response to Request for AdditionalInformation Regarding Generic Letter 96-05 Program at Calvert Cliffs Nuclear Power Plant, Unit Nos.1 & 2 (TAC Nos.

M97028 & M97029) _,,

REFERENCE:

(a) Letter from Mr. A. W. Dromerick (NRC) to Mr. C.11. Cruse (BGE),

January 29, 1999, " Request for Additional Information Regarding Generic Letter 96-05 Program at Calvert Cliffs Nuclear Power Plant, Unit Nos.1.and 2 (TAC Nos. M97028 and M97029)"

Reference (a) forwarded an information request regarding Generic Letter 96-05 " Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves." Responses to the request are provided in Attachment (1).

Should you have questions regarding this matter, we will be pleased to discuss them with you.

Very truly yours, 9904090158 990402 ~ \

PDR ADOCK 05000317 /

P PDR_ ,,

CliC/JMO/ dim O .

Attachment:

(1) Rcr.-use to Request for Additional Information Regarding Generic letter 96-05,

" Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves" cc: R. S. Fleishmau, Esquire 11. J. Miller, NRC J. E. Silberg, Esquire Resident inspector, NRC S. S. Bajwa, NRC R.1. McLean, DNR A. W. Dromerick, NRC J. II. Walter, PSC

l ATTACHMENT (1) 1

}

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 96-05, i

" PERIODIC VERIFICATION OF DESIGN-BASIS CAPABILITY {

]

OF SAFETY RELATED MOTOR-OPERATED VALVES" 4

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2 Baltimore Gas and Electric Company t Calvert Cliffs Nuclear Power Plant April 2,1999

l ATTACHMENT (1)

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC t ETTER 96-05, k '

CPERiODIC VERIFICATION OF DESIGN-BASIS CAPABILITY OF SAFETY-RELATED MOTOR-OPERATED VALVES" NILCJteauest Nod in I<t C Inspection Report No. 50-317 & 318/98 09, the NRC staf closed its review of the motor-operated valve (Af0V) program implemented as Calvert Cliffs Nuclear Power Plant (Calvert Chffs) in response to Generic Letter (GL) 89-10, " Safety-Related Afotor-Operated Valve Testing and Surveillance." In the inspection report, the NRC staff discussed certain aspects of the licensee's Af0V program to be addressed over the long term. For example the inspectors noted that (1) the licensee needed to revise procedures to correct globe valve thrust eqtntion inconsistencies; (2) the licensee was monitoring industry e.[ orts to validate the Electric Power Research Institute (EPRI) Performance Prediction Afodel (PPAf)for gate valves that exceed 18 inches; (3) additional modifications ;o improve the design-basis capability of the Pressuri er Power Operated Itel:-f Valve (PORV) block valves were planned as part of Calvert Chffs long term Af0V program; and (4) internal dimensions for Steam Generator Feedwater isolation valve 2-Af0V-4516 will be obtained and used in a new PPAf thrust calculation by early 1999. The licensee should briefly describe the current status of the aciions to address the specific long-term aspects of the Af0Vprogram at Calvert Chffs noted in the NRC inspection report.

BGEBesponse

1. The controlling procedure for MOVs, EN-1-ll4, Afotor Operated Valve Program, hes been revised to correct the globe valve thrust equation discrepancies.

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2. We consider the EPRI PPM as "best available information" when it is used on gate valves that are i greater than 18 inches. Our action is consistent with the approach taken by both MPR Associates, Inc. and EPRI (the developers of this product). We will continue to monitor information from other plants and the industry with respect to gate valve size, and to evaluate the information for impact on the MOV calculations as part of our periodic verification program.

3. Paragraph E8.2 of NRC Region 1 Integrated Inspection Report Nos. 50-317/98-09 and 50-318/98-09 states: j i'

The inspectors determind that the PORV block valves had adequate capability with design margins of appraimately 8-12%. Further improvement in the design basie -apability of the j PORV block valves was under consideration and was planned to be addressed as part of I Calvert Cliffs long-term MOV program.

Currently, the PORV block valves have high margin as defined in the Topical Report MPR-1807, Revision 2, which has been reviewed and accepted by the NRC. We have created a project to evaluate the long-term status of the PORV block valves and to explore improvements to margin if determined to be necessary. Ctwrently, no specific modifications are planned for the PORV block valves.

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4. We had planned to perform an internal inspection of one of the feedwater isolation valves, 2MOV4516, during the current 1999 Unit 2 refueling outage. The inspection would have been in conjunction with other valve work planned for the outage. The scope of valve work has changed, and an internal inspection will not be performed during this outage unless leakage on this valve warrants a repair. We are looking at various options to improve the capability of feedwater isolation valve actuators (l(2)MOV4516 and 4517). Currently, we pian to perform an internal I

e ATTACHMENT (1)

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 96-05,

" PERIODIC VERIFICATION OF DESIGN-BASIS CAPABILITY OF SAFETY-RELATED MOTOR-OPERATED VALVES" inspection on the next feedwater isolation valve that requires internal valve work. This plan may change as other methods are identified that will improve the margin on these MOVs. Valve 2MOV4516 is a low risk valve and, currently, has low margin (3.5%). It was last tested in 1997. 3

, We have scheduled a new static test for 2MOV4516 during the 1999 refueling outage. Our test l frequency is conservative, and is consistent with the low margin and low risk ranking of the l' valve. The maximum test frequency for the valve, as identified in Table 4-1 of Topical Report MPR-1807, Revision 2, is six years.

I NRC Request No. 2

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The Joint Owners ' Group (JOG) program specifies that the methodology and discrimination criteriafor I ranking Af0Vs according to their safety sigmficance are the responsibility ofeach participating licensee.

In a letter dated Afarch 13,1997, the licensee stated that Af0Vs will be evaluated based on risk insights and available margins. As Calvert Chffs' units are preuuri:ed-water reactors (PWRs) designed by l Combustion Engineerirg (CE), the licensee shoulddescribe the methodology asedfor risk ranking Af0Vs at Calvert Chffs in detail, including the preparation of sample lists of high-risk Af0Vs from other CE nuclear plants. In responding to this request, the licensee might apply insights from the guidance ,

provided in the Westinghouse Owners Group (WOG) Engineering Report V-EC-1658-A (Revision 2, l dated August 13,1998), " Risk Ranking Approachfor Afotor-Operated Va'ves in Response to Generic Letter 96-05," and the NRC safety evaluation dated April 11, 1998, on the WOG methodologyfor risk l ranking Af0Vs at Westinghouse-designed PWR nuclear plants. The licensee could also obtain insights ,

from an Af0Vrisk-ranking methodology developed by the Boiling Water Reactor Owners Group.

l l BGE Respon_se j We are planning to use the WOG MOV Risk Ranking Methodology (Engineering Report j l V-EC-1658-A, Revision 2, dated August 13, 1998). We are also working with the Cornbustion  !

Engineering Owners Group (CEOG) to obtain a sample matrix of hi$ risk MOVs from other CE plants. The current risk ranking of MOVs at CCNPP was performed in 1995, as part of our response l to GL 89-10. A!mough this ranking does not have the Icvel of detail recommended in the WOG l Methodology, performing a more comprehensive Probabilistic Risk Assessment (PRA) risk ranking at

, this time is not practical due to ongoing PRA model construction. When the PRA update is complete, l we intend to perform a new risk ranking following the guidance provided in the WOG Methodology. ,

The resulting new risk ranking is expected to be completed in the year 2000. In the interim, we plan I

, to use the current risk ranking in conjunction with an expert panel as discussed in the WOG

! guidelines to achieve a near-term update. After updating the PRA model, we will compare the results of the original risk ranking with the results obtained from the new model. Differences will be evaluated and documented. Although we intend to generally follow tM WOG guidelines, we smticipate that there may be areas where it is prudent to deviate from the WOG guidance as a result of differing Nuclear Steam Supply System designs and/or to reflect issues unique to our PRA and plant .

Any deviations will be justified by our PRA group. Until the PRA update is complete, and the new risk ranking performed using this rpdate, we will test all of the GL 89-10 MOVs in accordance with the JOG FL < versus Margin matrix, except that the maximum test frequency will remain at three refueling cycles.

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ATTACIIMENT (1)

RFSPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 96-05,

" PERIOD!C VERIFICATION OF DESIGN-BASIS CAPABILITY OF

. . SAFETY-RELATED MOT 4 OPERATED VALVES" The currently applied risk ranking is discussed below:

• The MOVs were binned into high, medium, low and low-low risk categories. The categories rencet the MOV's impact on core damage frequency and/or containment performance. The list of MOVs included in the risk radkg is the population of MOVs from our GL-89-10 MOV program.

• The assessment invo!ved both a quantitative ard qualitative evaluation. The quantitative evaluation was performed using the plant model as it existed in 1995 (Update i). About 80%

of the MOVs were contained in the Update-1 Plant Model. The importance of each MOV was estimated by failing the function most closely associated with the MOV. Since failitig the function can be quite conservative, a qualitative assessment in conjunction with the I

quantitative assessment was used to rank the MOVs. The ranking was performed by BGE Reliability Engineering staff. An expert panel was not used.

• The MOVs that were not contained in the plant model were evaluated qualitatively and placed in the appropriate risk category.

• Tne MOVs were ranked relative to one another. Four MOVs clearly had a significant impact.

These were placed in the high-risk category. About 60% of the MOVs had e minimal impact on core damage frequency. These were placed m the low-risk category. Within the low-risk l category was a sub-set of MOVs that had an even smallt-r impact on risk. These were placed in the lo.v-low-risk category. All remaining MOVs (about 33%), which had some impact on risk but not enough to make a significant impact, were placed in tbc medium-risk category.

• Consistent with current MOV risk-ranking guidelines, the risk assessment is based on demand l type failure modes and does not consider transfer failure modes. Common cause failure was not explicitly evaluated.

• The MOV's impact on Level-2 was performed by a qualitative assessment. For example, if an MOV's failure to operate would seriously impact containment cooling, containment spray or containment isolation, then the MOV would have a significant Level-2 impact and would be placed in the cppropriate risk category. Although some MOVs had a significant Level-2 impact, most did not.

NRC Request No. 3 In a letter dated June 30,1998, the fict mee updated its commitment to implement the JOG Program on Af0V Periodic Verification in response to GL 96-05. The JOG Program specifies that each valve included in the dynamic test program is to be tested a minimum of three times within a 5-year period, with each consecutive test separated by at least 1 year. This means that dynamic testing should be completed by Afarch 2002. The licensee's letter noted that CEOGjoined the JOG Af0Vprogram too late for Calvert Chffs to dynamically test any Af0Vs during the 1997 refueling outage, and that the third and finai dynamic tests on two Af0Vs will not be completed until the 2003 refueling outage. The licensee should briefly describe its plans for implementing the JOG periodic ver.fication final test criteria, including any effect caused by the extended dynamic test program at Culvert Chfp.

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ATTACHMENT (1)

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 96-05,

" PERIODIC VERIFICATION OF DESIGN-BASIS CAPABILITY OF SAFETY-RELATED MOTOR-OPERATED VALVES" BGE Respon We have committed to the JOG Program on MOV Periodic Verification, ac described in Topical Report MPR-1807, Revision 2. The commitment includes implementation of all three phases of the program: 1) Interim Static Tev Program; 2) Dynamic Test Program; and 3) Final Program. Our late entry into the 300 Program, aue to the late entry of CEOG in to the program, will cause us to complete the third, and final, JOG dynamic tests no sooner than 2003. However, since we are still a full JGG panicipar,t, we expect no effect on our long-term periodic verification program. We will continue to share in the JOG results. We will be advised of any degradation mechanisms associated with the type of valves instalid ie. our plant, as they are noted during the JOG Program. We will take action to adequately. address any identified degradation mechanisms that are reasonably expected to be applicable to our valves.

NRC Request No. 4 In a letter dated Afarch 13,1997, the licensee stated that new diagnostic technologies that monitor Af0V performance at the motor control center (MCC) may be used, as appropriate. The licensee should briefly describe its plansfor the use oftest datafrom the MCC including (1) correlation ofnew MCC test ,

, data to existing d:-ectforce measurements; (2) interpretation ofchanges in MCC test data to changes in j MOV thrust and torque performance; (3) consideration of system accuracies and sensitivities to MOV degradation for both output and operating performance requirements; and (4) validation of MOV j opembility using MCC testing.

BGE Response We currently un the Liberty Technologies Valve Operation, Test ar.d Evaluation System (VOTES)

"at-the-valve" diagnostic technology to periodically monitor MOV performance. We are evaluating the use of MCC-based diagnostics as replacement for at-the-valve testing on selected valves, but currently use this new technology only as supplemental diagnostics. The~MOV Users Group is in the process of developing a document that will provide guidance on the requirements of an MCC-based

periodic test program. We plan to consider program modificatbns as appropriate when this guidance docu'nent is completed. Currently, we expect the document to be completed later thic year. If we make a decision to use MCC technology in place of the existing VOTES equipment, we will address the following issues

1. The new MCC test data will be directly correlated to existing direct force measurements, or to changes in these measurements.

2. A methodology will be in place to interpret the changes in MCC test data to changes in MOV ,

thrust and/or torque performance. l

3. The effect of system accuracies and sensitivities to MOV degradation will be addressed fer .l both actuator output and operating performance requirements. l

4. An appropriate validation of the MCC technology will be in place. i l

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ATTACHMENT (1)

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 96-05,

" PERIODIC VERIFICATION OF DESIGN-BASIS CAPABILITY OF l

SAFETY-RELATED MOTOR-OPERATED VALVES" j NRC Reauest No. 5 The JOG Program focuses on the potential age-related increase in the thrust or torque required to i operate valves under their design-basis conditions. In the NRC safety evaluation dated October 30,1997, on the JOG Program, the NRC staff specified that licensees a e responsible for addressing the thrust or torque delivered by the MOV motor actuator and its potential degradation. In addition, N1'C Inspection Report No. 50-317 & 318/98-09 noted that the licensee was addressing l Limitorque's Technical Update 98-01 by revising actuator output calculations to include more conservative pullout efficiencies and applicationfactors of 0.90. Therefore, the licensee should briefly l provide the current status of actions at Calvert Chffs for ensuring adequate ac and de MOV motor l actuator output capability, including consideration of recent guidance in Limitorque Technical l Update 98-01 and its Supplement 1.

BGE Responic l

We had already adopted and implemented the guidance provided in Limitorque Technical Update 98-01. Paragraph E8.1.b of NRC Region i Integrated Inspection Report Nos. 50-317/98-09 and 50-318/98-09 states:

BGE addressed new industry guidance on Limitorque motor actuator output capability, using gear pullout efficiency in its MOV sizing and switch setting calculations and a 0.9 application ,

, factor in design calculations. BGE documented its evaluation of Limitorque Technical Update 98-01 and its Supplement 1 in [ Engineering Service Package]

l ESP No. ES 199801215-000.

l We continue to obtain and trend static test data from the GL 96-05 MOVs. The data includes the

acquisition of'As Found' test data, when practical. In addition, we will trend the dynamic test results obtained from the four MOVs that we are testing in the JOG Program. Any indication of degradation from this testing will be evaluated as part of our MOV trending program to address actuator and motor-related degradation. The JOG Program itself will identify and address potential valve aging related degradation.

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