IR 05000259/1991009
| ML18033B677 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 04/05/1991 |
| From: | Girard E, Jape F, Casey Smith NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18033B676 | List: |
| References | |
| 50-259-91-09, 50-259-91-9, 50-260-91-09, 50-260-91-9, 50-296-91-09, 50-296-91-9, GL-89-10, NUDOCS 9104230183 | |
| Download: ML18033B677 (10) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
'I01 MARIETTASTREET, N.W.
ATLANTA,GEORGIA 30323 Report Nos.:
50-259/91-09, 50-260/91-09, and 50-296/91-09 Licensee:
Tennessee Valley Authority 6N 38A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Docket NoseI 50-259, 50-260, and 50-296 License Nose I
'nd DPR-68 Facility Name:
Browns Ferry Units 1, 2, and
Inspection Conducted:
March 18 - 22, 1991 Inspectors:
.
H.
>rard ca'
jQM.
C. Smith Approved by: E-.
X.
Fe Jape, hief Test Programs Sec ion Division of Reactor Safety-c e~
Date igned,
> 8/VI te Signed Date Signed SUMMARY Scope:
This routine announced inspection assessed the actions taken by TVA in responding to Supplement 3 of Generic Letter (GL) 89-10 for Browns Ferry Unit 2.
Results:
TVA's actions in response to Supplement 3 of GL 89-10 were determined to be adequate.
Their overall GL 89-10 program and its implementation will be assessed in subsequent NRC inspections.
A concern was identified during the inspection regarding oily fluid observed leaking from the limit switch gearbox of a Limitorque actuator.
TVA committed to actions to assure this leakage does not adversely affect actuator operability, as described in paragraph 2 below.
No violations or deviations were identified.
9104230i83 9i0405 PDR ADOCK 0500025'
REPORT DETAILS Persons Contacted Licensee Employees:
- J. Davenport, Site Licensing
- J. Elmerick, Design Engineer, Nuclear Engineering
- J. Endsley, Preventive Maintenance, Motor Operated Valve Coordinator
- J. Kurtz, Project Manager
- L. Myers, Plant Manager
- M. Herrell, Operations Manager
- M. Bajestani, Technical Support Manager
- P. Salas, Compliance Supervisor
- J. Schlessel, Preventive Maintenance Supervisor
- R. White, Design Engineer, Nuclear Engineering
- 0. Zeringue, Site Director Licensee Contractor:
N. Schauki, Principal Engineer, Universal Testing Laboratories, Incorporated NRC Personnel:
W. Bearden, Resident Inspector E. Christnot, Resident Inspector G.
Humphrey, Resident Inspector
- K. Ivey, Resident Inspector J.
Jacobson, Office of Nuclear Reactor Regulation
- C. Patterson, Senior Resident Inspector T. Scarbrough, Office of Nuclear Reactor Regulation
- Attended exit interview Licensee Actions in Response to Supplement 3 of Generic Letter (GL) 89-10 for Browns Ferry Unit 2 NRC Office of Nuclear Regulation (NRR) personnel and Region II inspectors assessed the adequacy of the actions taken in response to Supplement 3 of GL 89-10 and determined that they were adequate.
Several matters were noted which are to be examined further in subsequent NRC inspections of TVA's overall response to GL 89-10.
In particular, a
concern was identified regarding oily fluid observed leaking from the limit switch gearbox of a Limitorque actuator.
Details of the inspection and findings are described below.
The NRC staff issued Supplement 3 to Generic Letter (GL). 89-10, "Safety-Related Motor-Operated Valve Testing and Surveillance,"
on October 25, 1990.
It requested each BWR licensee to perform a plant specific safety analysis in 90 days and to evaluate within 120 days the capability of the
motor operated valves (MOVs)
used for isolation in the steam supply lines of the High Pressure Coolant Injection (HPCI)
and Reactor Core Isolation Cooling (RCIC)
systems, in the supply line of the Reactor Water Cleanup (RWCU) system, and in the lines to the Isolation Condenser, as applicable.
On December 10, 1990, TVA reported that the Browns Ferry plant-specific safety assessment was available on site for NRC staff review.
On March 13, 1991, TVA provided its evaluation of the capability of the MOVs used for containment isolation in the HPCI, RCIC, and RWCU systems (2 MOVs in each system) at Browns Ferry Unit 2.
Browns Ferry has no Isolation Condenser.
The six valves identified were as follows:
RWCU System Valves 2-FCV-69-01 ( Inboard Isolation)
2-FCV-69-02 (Outboard Isolation)
RCIC System Valves 2-FCV-71-02 ( Inboard Isolation)
2-FCV-71-03 (Outboard Isolation)
HPCI System Valves 2-FCV-73-02 ( Inboard Isolation)
2-FCV-73-03 (Outboard Isolation).
TVA indicated that their evaluation in response to Supplement 3 of GL 89-10 confirmed that the valve operators and torque switch settings for these valves were adequate and that no deficiencies had been identified which would require corrective action.
In their discussions with NRR'nd Region II personnel, TVA noted that improvements had been made in the performance capabilities of several of the valves since the April 1990 public meeting on the results of NRC-sponsored MOV tests.
They had increased the torque switch setting of one of the HPCI MOVs and replaced the motor, gearing and cable of the other.
They also replaced the gearing in a RCIC MOV and a spring pack in a RWCU MOV.
Measurements of the thrust delivered at torque switch trip were determined for each of these valves following the changes.
The NRC assessment of TVA's response was conducted through review of related documentation (the response letters to the NRC, design calculations and supporting data, etc.),
inspection of the involved valves,,and discussions with responsible TVA personnel.
The discussions included conference calls NRR and Regional personnel held with TVA on March 19, 20, and 22.
Documentation reviewed and inspections conducted were as follows:
DOCUMENTATION Supplement '3 response letters dated December 10, 1990 and March 13, 1991 TVA Calculation MD-Q2999-910023, HPCI, RCIC, RWCU Isolation MOV Operator Thrust Capability TVA Nuclear Power Mechanical Design Standard DS-M18;2.21, Issued 2/21/91=
Engineer'ing Assessment, Isolation Function of MOVs for HPCI and RCIC Steam Supply Lines and RWCU Water Supply Line, November 30, 1990 Maintenance history (computer printout) for six GL 89-10, Supplement
MOVs since about November 1984 Stroke time surveillance test results for six GL 89-10, Supplement 3 MOVs in 1991 Valve Vendor Required Thrust Calculations RWCU Valves - 'Velan Report DC-004 RCIC Valves - Crane Calculation OTC-244 MPCI Valves
-
Crane/Chapman Calculation OTC-259 (with additional TVA Calculation DCN-F4279A)
Letter From Limitorque Corporation to Duane Arnold Energy Center dated April 30, 1987, Subject:
Limitorque Type SMB Thrust Ratings (states SMB actuator designs have been tested for a
one time thrust overload condition of 250 percent of rating)
Written and Signed Record of Telecon Between Limitorque and TVA dated March 20, 1991, Subject:
Operator Capability Penalty for Voltages Within 10 Percent of Rated Motor Voltage (states motor can handle voltage fluctuations of
percent with no degradation of output torque)
Letter From Limitorque Corporation to TVA dated February 21, 1991, Subject:
Engineering Data for Limitorque Actuators (states that run efficiency could be used for actuator closing motor torque determinations)
INSPECTIONS External visual examination of all six valves for indication of correctly installed fasteners and gaskets and for proper stem lubrication
~
~
Verification that motor, actuator, and valve data are consistent with that used in design calculations for all six valves Observation of the general condition of limit and torque switches after the removal of the switch covers from valves 2-FCV-69-01 and 2-FCV-69-02 TVA indicated that, in evaluating the capability of the MOVs, data from the NRC-sponsored MOV tests were used to provide confidence that calculated thrust requirements were sufficient to close the valves under design-basis differential pressure and. flow. conditions.
From static tests of the MOVs using MOVATS diagnostic equipment, TVA has measurements of the thrust delivered by the actuator at closing torque switch trip.
TVA also calcu'lated the overall operator capability for closing each valve, The NRC reviewed TVA's cal,culations for. closing actuator capability and discussed those calculations with the responsible personnel.
The calculations and actions to demonstrate the closing capability of the six MOVs in response to Supplement 3 to GL 89-10 are considered acceptable.
TVA will further confirm the capability of these MOVs during the imp'lementation of their GL 89-10 program.
For example, it is understood that TVA will discuss with Limitorque the fact that the close torque switches for the RWCU MOVs trip at thrust values that are near the published rating for the actuator and whether limitations in allowable cycles arise as a result of thrust overshoot.
TVA will continue to monitor actuator performance and lubrication frequencies to ensure that the 0. 15 stem friction coefficient used
.in their
- calculations was appropriate.
They will also address opening capability for these MOVs in their GL 89-10 program.
Nevertheless, the opening capability of the MOVs under high differential pressure conditions was discussed with TVA and no
.current concerns were identified in this area.
NRR and Region I1 will again review TVA's demonstration of the capability of these MOYs in inspections of their GL 89-10 program and its implementation.
External inspections of the valves and verifications of motor, actuator and valve nameplate data revealed no deficiencies, though two valves could not be fu'lly examined because'f potential contamination of the inspector by possibly radioactive water (2-FCV-73-02)
and accessibility (2-FCV-71-02).
The switch compartment inspections performed on two valves revealed generally good conditions, except that a small amount of oily fluid was observed to have leaked from the limit switch gearbox to the inner surface of the switch compartment in valve 2-FCV-69-01.
The presence of this f'luid within the limit switch compartment can lead to electrical problems because of the close proximity of contacts, wiring and terminals.
Also, it suggests possible degradation of the grease.
The NRC personnel indicated to TVA the importance of determining the cause of the leak and demonstrating that this is not a generic problem for other
e MOVs at Browns Ferry.
TVA personnel stated that the grease used in the gearbox was in accordance with the actuator manufacturer's (Limitorque)
current recommendations.
They reported they had initiated the following actions:
Limitorque was contacted and preliminary discussions indicated that some separation of the gearbox grease was to be expected, accounting for the oily fluid.
Further discussions were planned to ascertain what amount of separation should be considered significant and what degradation could result from contamination of internal wiring and components with the oily fluid.
The preventive maintenance task data base will be reviewed for other reported instances of the leakage to. aid in determining the size of the problem.
A standard preventive maintenance task will be performed on valve 2-FCV-69-01 to further investigate the cause of the leakage.
Safety-related Unit 2 Limitorque operators will be identified whose orientations
'are most likely to increase the consequences of contamination by the oily fluid.
A minimum of five of these will be visually inspected for the problem prior to Unit'
restart.
The NRC inspectors on site specifically asked site management if the latter of the above actions could be considered a
commitment and were informed that it was.
3.
Exit Interview The inspection scope and findings were summarized on March 22, 1991, with those persons indicated in paragraph 1.
The inspectors described the areas inspected and discussed in deta'il the inspection results..
TVA was informed that their response to Supplement 3 of GL 89-10 was considered
'cceptable and that their overall response to GL 89-10 would be examined in subsequent NRC inspections.
A specific concern was described with regard to th'e possibly degrading effects of oily fluid observed leaking in the switch compartment of a
safety-related valve actuator'xamined during the NRC inspection.
The NRC expects TVA to evaluate the cause and consequences of this leakage.
Plant management committed to identify safety-related valve actuators whose orientation would increase the potentially adverse consequences of such leakage and to examine at least five for evidence of the problem prior to Unit 2 startup.
Oissenting comments were not received.
Proprietary information is not contained in this report.