ML20149D787
| ML20149D787 | |
| Person / Time | |
|---|---|
| Site: | Fermi, Grand Gulf  |
| Issue date: | 12/20/1993 |
| From: | Wiggins J Office of Nuclear Reactor Regulation |
| To: | Gibson A, Grant G, Hodges M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| RTR-NUREG-1275 GL-89-10, GL-91-18, NUDOCS 9401050013 | |
| Download: ML20149D787 (4) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION WASHINoToN. D.C. M
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..E. 2 0 15 MEMORANDUM FOR:
M. Wayne Hodges, Director Division of Reactor Safety, RI Albert F. Gibson, Director 4
Division of Reactor Safety, RII Geoffrey E. Grant, Director Division of Reactor Safety, RIII J
Samuel J. Collins, Director Division of Reactor Safety, RIV Kenneth E. Perkins~, Jr., Director Division of Reactor Safety and Pro,jects, RV FROM:
James T. Wiggins, Acting Director Division of Engineering Office of Nuclear Reactor Regulation
SUBJECT:
INTERIM INSPECTION GUIDANCE ON PRESSURE LOCKING
'i AND THERMAL BIWING 0F GATE VALVES i
In March 1993, the NRC staff issued NUREG-1275, Volmse 9, " Pressure Locking D
and Thennal Sir. ding of Gate Valves,' to summarize the-staff's review of -
operating events involving pressure locking and thermal binding of gate valves.
In response to this report, the staff revised Temporary Instruction (TI) 2515/10g, " Inspection. Requirements for Generic Letter (GL) 89-10, Safety >
Related Motor-0perated Valve Testing and Surveillance,"-to request that NRC inspectors verify during their inspections of GL 89-10 programs that licensees are addressing the potential for pressure locking and ttermal binding of gate valves.
Further, the staff provides information.to nuclear >ower plant licen-sees on acceptable methods to address pressure locking and tnormal binding of gate valves in Supplement 6 to GL 89-10 (which should be issued soon).
In February 1993, the Nkt staff conducted an inspection of the GL 89-10 program'at the Ferst-2 Nuclear Power Plant ~and reviewed the licensee's action to address pressure locking and thermal binding of gate valves.
Region _III 1
categorized the pressure locking issue as unresolved in the inspection report because ~of concerns regarding the evaluation of motor-operated valves (MOVs).
determined by the licensee to be susceptible to pressure locking. On September 13, 1993, the. staff met'with the licensee to' discuss its actions to
-address pressure locking and thermal binding-in response'to the inspection-report.
The licensee stated that it had found six'MOVs to'be susceptible 'to E
pressure locking and was planning to determine appropriate modifications-dur k; the'next outage in March 1994. 'In response to staff questions on the current functionality of those six MOVs, the licensee adopted a methodology 1
developed at.the Grand Gulf Nuclear Power Plant to estimate the thrust-required to overcome pressure locking for the six MOVs. The staff has not evaluated the Grand Gulf methodology at this time; however, the licensee's preliminary evaluation found three MOVs to not meet the thrust requirements-2500]O
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Regional Division Directors 2
predicted by the Grand Gulf methodology.
In light of this information, the licensee is reevaluating those MOVs for their susceptibility to pressure locking, thrust requirements, available voltage, and stem friction coefficient. The licensee has committed to complete its review in the next few weeks and to submit its completed evaluation of the current functionality of these HOVs on '.he docket.
The sta'f will review the licensee's evaluation when submitted.
In view of the slowness in the licensees' progress toward resolving this issue, NRR is drafting a generic communication, proposed to request that i
licensees take acthn to address pressure locking and thermal binding of gate valves within a specific time schedule.
The generic communication will most likely be a new generic letter.
In addition, the staff has scheduled a public workshop to discuss pressure locking and thermal binding of gate valves for February 4,1994, in New Orleans, following the winter meeting of the MOV Users Group of nuclear power plant licensees.
1 Until the new generic communication is issued, we are providing the following interim guidance to regions for the review of licensee action to address pressure locking and thermal binding of gate valves: NRC inspectors should verify that licensees are evaluating their safety-related MOVs to identify those susceptible to pressure locking and thermal binding. Upon determining that an MOV is susceptible to pressure locking or thermal binding, a licensee i
should evaluate the current functionality of the MOV. GL 91-18 (November 7, 1991), "Information to Licensees Regarding Two NRC Inspection Manual Sections on Resolution of Degrad6d and Nonconforming Conditions and on Operability,"
provides guidance for licensees in evaluating the functionality of safety-related components.
If a licensee cannot justify the continued functionality of an MOV found to be susceptible to pressure locking or thermal binding, the licensee should consider the MOV to be inoperable and take appropriate action.
In such an instance, the licensee may propose mitigating actions, or may provide further analyses, in support of a request for enforcement discretion to allow continued plant operation untti the next outage when appropriate modifications would be performed. The NRR Mechanical Engineering Branch a
'should participate in the decision to grant enforcement discretion.
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While further inspection guidance is being prepared, the regions should categorize as " unresolved" the licensee's method for identification of susceptible MOVs and its method of estimating the thrust requirements to overcome pressure locking and thermal binding.
If resolution of those unresolved items is needed, prior to our finalizing the generic letter, refer those issues to NRR.
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Regional Division Directors 3
' If you have any questions regarding this interim inspection guidance on pressure locking and thennal. binding of gate valves, please contact James A. Norberg, Chief, Mechanical Engineering Branch, NRR, at 301-504-3288.
ORIGINALSIGNEDBP.
JvnesT.ynggins i
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James T. Wiggins, Acting Director'
. Division of Engineering 4
Office of Nuclear Reactor Regulation-cc:
W. T. Russell i
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S/Jv/99 NOTE TO:
J. McKnight Document Control Desk FROM:
T.Scarbrough7gS' EMEB/NRR
SUBJECT:
MEMORANDUM FROM J. WIGGINS TO REGIONS DATED DECEMBER 20, 1993 i
Please have the attached document made available in the NRC Public Document Room.
cc:
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