IA-97-177, Discusses Potential 10CFR21 Reportable Concern from Crane Valves on Weak Link Analyses,Per .Considers Action Taken by Crane to Be Reasonable in Alerting Nuclear Utils to Updated Weak Link Calculations for MOVs Used in Plants

Discusses Potential 10CFR21 Reportable Concern from Crane Valves on Weak Link Analyses,Per .Considers Action Taken by Crane to Be Reasonable in Alerting Nuclear Utils to Updated Weak Link Calculations for MOVs Used in Plants

ML20217F557
Person / Time
Site:	San Onofre
Issue date:	04/07/1997
From:	Terao D NRC (Affiliation Not Assigned)
To:	Chaffee A NRC (Affiliation Not Assigned)
Shared Package
ML20213F483	List: IA-97-177, Discusses Potential 10CFR21 Reportable Concern from Crane Valves on Weak Link Analyses,Per .Considers Action Taken by Crane to Be Reasonable in Alerting Nuclear Utils to Updated Weak Link Calculations for MOVs Used in Plants ML20213F480 ML20213F484 ML20214D079 ML20217F549 ML20217F557
References
FOIA-97-177 IEB-85-003, IEB-85-3, NUDOCS 9708060135
Download: ML20217F557 (2)

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' g ,) NUCLEAR RECULATCRY COMM ION e '# WASHINoToN, o.C. 30MWMoot

%***** April 7, 199 MEMORANDUM 10: Alfred E. Chaffee, Chief Events Assessment and eneric Connunications Branch Division of Reactor rogramfanagement David Terao, Section Chief

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FROM: t Com)onents & Testin Fectio ~

Meclanical Engineer ng Branch Division of Engineering

SUBJECT:

POTENTIAL 10 CFR PART 21 REPORTABLE CONCERN FROM CRANE VALVES ON WEAK LINK ANALYSES in a letter dated May 16, 1994, Crane Valves Nuclear Operations (Crane) advised the NRC, in accordance with the reporting requirements of 10 CFR Part 21, that it was undertaking an evaluation to determine if data supplied in the mid-1980s as Crane Aloyco Operating Thrust Calculation (0TC) reports had been misused by nuclear utilities to set torque switches in motor-operated valves (MOVs). In the May 1994 letter, Crane stated that the issue involved use of data beyond the intended scope and not the adequacy of its analytical nethods. The issue was said to have surfaced as a result of the review of revised OTC reports supplied to Florida Power Corporation for MOVs at the Crystal River nuclear power plant.

In a letter dated January 12, 1995, Crane notified the NRC that its evaluation was complete. Crane stated that, in the 1980s, it had used a model to predict thrust required to operate valves in essential safety systems for its nuclear power plant customers in response to NRC Bulletin 85-03. Beginning in 1993, nuclear utilities requested Crane to perform support analyses for specified design conditions which included parameters not analyzed in the original model. Crane stated that the potential Part 21 concern arose because the results generated from the current model differed from those of the original model.

In its January 1995 letter, Crane stated that it had reviewed the original purchase orders to confirm that the supplied analytical information matched the utility's request. The Crane model used in the 1980s was said to have considered design pressure, differential pressure, ambient temperature, operator thrust, and yield stress. Since late 1993, nuclear utilities have requested Crane to perform analyses with specified design-basis conditions including extended structure mass, extended structure center-of-gravity, ASME and AISC allowable stress, and dynamic loads. In performing these more-recent analyses, Crane uses a model that also considers bending moments and torsion loads. The Crane analyses using the current .aodel are said to be able to identify the weak link in the valve-motor operator assembly as a function of design-basis conditions.

CONTACT: T. Scarbrough 415-2794 9708060135 970728 PDR FOIA FOWLER 97-177 PDR

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A. Chaffe'e 2 in the January 1995 letter, Crane stated that the nuclear utilities were supplied with the analyses they requested. Crane stated that it has been in contact with many utilities to provide support for them to better understand, or predict, the performance of safety-related MOVs. Crane also provided its customers with an analysis using the current model addressing the additional factors, when requested. As a result, Crane believed that the data supplied in prior analyses did not constitute a reportable item under 10 CFR Part 21.

The NRC staff has reviewed the question of a potential generic concern regarding the capability of MOVs sized and set based on the original Crane model. To assist the NRC staff in completing its review, we requested in a letter dated August 5, 1996, that Crane indicate whether any MOVs considered acceptable under the original model were subsequently determined to be unacceptable when using the current model. If so, we requested Crane u identify the aaplicable facilities and plant systems, and the follow-up action by Crane and t1e specific utility. The staff also requested an example of the typical concern identified when the current model was used to evaluate the capability of a previously analyzed MOV. Finally, the staff requested that Crane indicate the method by which Crane ensured that its customers had identified previously analyzed MOVs that might be deemed unacceptable in their sizing or setup based on the current model.

In a letter dated March 7, 1997, Crane provided a response to the NRC request for additional information on the updated analytical support for MOV weak link evaluations provided by trane to nuclear utilities. In its letter, Crane indicated that the problem surrounding the OTC calculations did not involve adequacy of its analysis methods, but rather the potential misapplication of the calculation results. Crane stated its belief that the subject reports meluded sufficient information and warnings so that utilities may be expected to make appropriate use of the information. Crane stated that, to the best of its knowledge, no MOVs considered acceptable under the OTC calculations were subsegeontly determined to be unacceptable by the current model when they were analyzed for the same conditions. As an example of the communication between Crane and nuclear utilities, Crane noted that the updated calculations provided more detailed infermation on the thrust limits and weak link location.

Based or. Our review of this issue, we consider that the action taken by Crane to be reasonable in alerting nuclear utilities to the updated weak link calculations for MOVs used in nuclear power plants. Through our interaction with the NRC Region offices, we will provide assistance to NRC inspectors where questions arise regarding the performance of weak link calculations for MOVs manufactured by Crane. Therefore, we believe that NRC staff review of this potential 10 CFR Part-21 reportable concern may be closed, m