ML20234D592
| ML20234D592 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/30/1987 |
| From: | Ireland R, Norman D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20234D544 | List: |
| References | |
| 50-285-87-17, IEB-85-003, IEB-85-3, IEIN-86-029, IEIN-86-29, NUDOCS 8707070269 | |
| Download: ML20234D592 (6) | |
See also: IR 05000285/1987017
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APPENDIX B
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U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
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NRC Inspection Report:
50-285/87-17
License:
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Docket:
50-285
Licensee: Omaha Public Power District (0 PPD)
1623 Harney Street
Omaha, Nebraska
68102
Facility Name:
Fort Calhoun Station, Unit 1 (FCS)
Inspection At:
Fort Calhoun, Nebraska
Inspection Conducted:
June 8-12, 1987
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Inspector:
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D. E. Norman, Reactor Inspector, Engineering
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Section, Reactor Safety Branch
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Approved:
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R. E. Ireland, Chief Engineering Section
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Reactor Safety Branch
Inspection Summary
Inspection Conducted June 8-12, 1987 (Report 50-285/87-17)
Areas Inspected:
Routine, unannounced inspection of actions relative to
IEB 85-03, IEN 86-29, and previously identified inspection finding 285/8616-01.
Results: Within the areas inspected, one violation was identified.
(285/8717-02, paragraph 2.a.(3).)
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8707070269 870701
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ADOCK 05000285
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DETAILS
1.
Persons Contacted
Omaha Public Power District (OPPD)
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- D. Munderloh, Senior Engineer, Nuclear Regulatory & Industry Affairs
- K. Morris, Division Manager, QA/RA
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- G. Gates, Manager, Fort Calhoun Station
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- A. Richard, Manager, Quality Assurance
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- J. Gasper, Manager, Administrative & Training Services
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- M. Core, Supervisor, Fort Calhoun Station Maintenance
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- R. Andrews, Division Manager, Nuclear Production
J. Drahota, Senior Engineer, Nuclear Production
D. Hendry, Maintenance Engineer, Fort Calhoun Station
J. Fisicaro, Supervisor, Nuclear Regulatory & Industry Affairs
NRC
- P. Harrell, Senior Resident Inspector, Fort Calhoun Station
- Denotes those present at the exit interview.
2.
Inspection Summary
a.
IEB 85-03 (Closed)
IEB 85-03, " Motor Operated Valve Common Mode Failure During Plant
Transients Due to Improper Switch Settings," was issued as a result
of several events during which motor operated valves (MOVs) failed on
demand due to improper switch settings.
The Bulletin requested that
MOVs in certain systems be tested for operational readiness, and that
licensees develop and implement a program to ensure that valve
operator switches are selected, set, and maintained properly to
accommodate maximum differential pressure expected during both
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opening and closing of the valve for both normal and abnormal events
within the design basis.
The licensee submitted a response to the
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Bulletin on May 15, 1986, and submitted additional information
requested by the NRC on September 15, 1986.
The inspection was performed to followup on the licensee's activities
taken in response to IEB 85-03 and commitments made by the licensee
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in submittals regarding the Bulletin.
The inspection scope included
the following:
(1) Program Review - The commitments made by the licensee in the
submittals to NRC are implemented by several procedures which
are now in place, and which were used for resetting motor
operated valve switches during the 1987 refueling outage.
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switches were originally set, in response to the Bulletin,
during the 1985 outage.
The following procedures, which
implemented the program were reviewed by the NRC inspector:
MP-MOV-3A, Revision 0, dated March 31, 1987, " Calibration
and Adjustments of Motor Operated Gate and Globe Valves"
MP-MOV-1, Revision 7, dated April 3,1987, " Motor Operated
"Limitorque" Valves Type SMB/HMB Limit Switch and Torque
Switch Replacement and Adjustment Procedure"
MP-MOV-3C, Revision 0, dated March 31, 1987, " Calibration
of the M0 VATS Motor Load Unit"
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SP-SI-HPSI, Revision 0, dated March 26, 1987, "HPSI Stop
Valves Special Test"
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Practices for accurately setting the switches to prevent
occurrences as described in the Bulletin were addressed in the
procedures and included:
Specific procedure for determining switch setting values.
Requirement that torque switch settings consider backlash
by setting bypass margin at the time the valve begins to
lift.
Requirement that torque switches-be set with spring pack in
a relaxed condition.
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Checking for backseating by turning handwheel after limit
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switch trip.
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The licensee's program provides reliable operation of MOVs by
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utilizing the Motor Operated Valve Analysis and Test
System (M0 VATS), a system which permits testing, adjusting, and
setting of limit switches, torque switches, and torque switch
bypass which are part of the controls for a M0V. M0 VATS is a
portable signature analysis system designed for field use and
displays and stores the following data:
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axial motion of the worm
motor current
stem load (thrust)
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actuations of torque and limit switches and the torque
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switch bypass
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The valves within the scope of IEB 85-03, each in the HPSI
system are as follows:
HCV-311, HCV-312, HCV-314, HCV-315,
HCV-317, HCV-318, HCV-320, and HCV-321.
Each valve was tested
and switches were set in accordance with MP-MOV-3A. During a
subsequent test conducted in accordance with SP-SI-HPSI it was
verified that the valves would cycle at or near the maximum
expected delta pressure across the valves.
In addition to the IEB 85-03 valves, the M0 VATS system was used
to test all safety-related MOVs at FCS. These tests were
performed at static conditions (no delta pressure across valve).
During the review of MP-MOV-3A it was identified that the
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procedure would permit setting of the torque switch at a value
which exceeds the design limits of the operator.
For instance,
design limits (torque switch setting) of an.SMB-00 operator is
14,000 lbs. The procedure permits a maximum setting of
14,575 lbs. All of the IEB 85-03 torque switches were set below
the design limits.
Pending licensee review of all other
safety-related operators to ensure that design limits have not
been exceeded, and a change to the procedure to prevent torque
switches from being set too high, this is considered an
unresolved item (285/8717-01).
(3) Data Review - IEB 85-03 reported that valves failed to operate
because the torque switch bypass had not been set to remain
closed long enough to provide the necessary bypass function on
valve opening with differential pressure conditions across the
valve.
Switches were reportedly set for 5 percent of full
stroke.
FCS procedures require,the bypass to be set between 10
and 15 percent of the stroke time after the valve begins to
unseat.
Open limit switches were set to trip at approximately 95 percent
of full stroke.
After the limit switch had tripped, the
handwheel was turned to bring the valve against the backseat to
ensure that backseating had not occurred.
Data reviewed by the
NRC inspector showed no evidence of iackseating; this indicated
that the 95 percent limit switch setting was adequate to prevent
backseating,
Review of as-left data showed that all thrust switch settings
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were within design limits of the operators. As-found data for
the initial M0 VATS tests performed during the 1985 outage showed
that five of the eight HPSI valve operators had been operating
above the allowable thrust limit established by Limitorque.
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This condition had not been identified by the licensee, and
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there was no evaluation showing that the valve operators were
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acceptable for continued operation.
After this discovery, the
licensee reviewed as-found data for all remaining safety-related
valve operators and found that two had been operating above the
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maximum allowable thrust. .In order to determine operability of
the over-thrust operators, the licensee contacted an engineering
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firm to perform a preliminary stress analysis, based on fatigue.
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testing, of the worse-case loading conditions. The' analysis
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show the following:
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The valve operators are acceptable from a structural and
continued operability ',tandpoint for a total of 240 cycles.
-(It was estimated that the operator has 200 cycles to
date).
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Additional testing is required to justify continued
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operation beyond 240 cycles at the as-left thrust switch
settings.
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The failure of the licensee to identify the over thrust
condition and to take corrective action is considered a-
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violation of NRC requirements.
(285/8717-02)
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b.
IEN 86-29 (Closed)
IEN 86-29, " Effects of Changing Valve Motor Operator Switch
Settings," was provided as an alert that setting torque bypass
switches to meet requirements of IEB 85-03 could affect valve
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position indicators and signals such as "permissives" to'other
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equipment.
The problem occurs when the torque bypass switch and
valve position indicator share the same limit switch rotor.
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Therefore, when the position of the-rotor was changed-to extend the
range of the torque bypass switch,!the valve open or close position
indication was also changed and did not reflect.the actual-position
of the valve. The licensee has issuec' a memorandum to operations
personnel. instructing them that it is necessary to hold the control
switch in the open or close position for five additional seconds
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after the indicator lights indicate the. valve position. The licensee
stated that "permissives" and emergency valve operation would not be
effected by the false indicators. This item is considered closed.
c.
Followup on Previous Inspection Items
(Closed) Violation 285/8616-01 - This violation resulted from the
acceptance of safety-related cable by the licensee without adequate
documentation to show that all procurement' specification requirements
had been met.
Specifically, the Certificate of Conformance (C0C) did.
not identify that the item being certified was Rockbestos
Firewall III cable; therefore, it was not possible to trace the cable
to a Qualification Test Report. The following actions were taken by
the licensee and verified by the NRC inspector:
(1) Documentation was added to the purchase order file to correct
the omission of Firewall III on the' C00.
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(2) Purchasing specifications were revised to require certification
to a specific qualification test report.
This item is considered closed.
3.
Exit Interview
The NRC inspector met with the licensee representatives denoted in
paragraph 1 and with Mr. P. H. Harrell, NRC Resident Inspector, on
Jure 12, 1987, and summarized the scope and findings of the inspection,
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