IR 05000482/1993002
| ML20045A522 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 06/03/1993 |
| From: | Westerman T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20045A520 | List: |
| References | |
| 50-482-93-02, 50-482-93-2, GL-89-10, NUDOCS 9306110026 | |
| Download: ML20045A522 (16) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
Inspection Report:
50-482/93-02 Operating License: NPF-42 l
Licensee: Wolf Creek Nuclear Operating Corporation P.O. Box 411 Burlington, Kansas 66839
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Facility Name: Wolf Creek Generating Station Inspection At:
Burlington, Kansas Inspection Conducted: May 3-7, 1993 Inspectors:
M. Runyan, Reactor Inspector, Engineering Section Division of Reactor Safety R. Vickrey, Reactor Inspector, Engineering Section, Division of Reactor Safety, Region IV
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Accompanying Personnel:
A. Trusty, Consultant, EG&G Idaho-INEL 7-
6-3-93 Approved:
T. Westerman, Chief, Engineering Section Date Division of Reactor Safety, Region IV Inspection Summary Areas Inspected:
Special, announced inspection of the implementation of the licensee's program to meet commitments to Generic Letter (GL).89-10, " Safety-Related Motor-Operated Valve Testing and Surveillance ' and followup on
corrective actions for violations.
Results:
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The licensee's motor-operated valve program was satisfactorily
demonstrating the capability of motor-operated valves subject to Generic Letter 89-10 and fulfilled the licensee's commitments in this area.
Quality control involvement was extensive (Section 1).
i Motor-operated valve design-basis reviews appeared comprehensive and
conservative (Section 1.1).
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The licensee had not established a margin for rate-of-loading effects.
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One valve was identified that appeared marginal based on the lack of a i
9306110026 930604 DR ADDCK 05000482 PDR
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-2-rate-of-loading margin. However, the licensee's test data indicated a rate-of-loading effect that generally provided greater rather than less margin under dynamic conditions. The rate-of-loading test results at Wolf Creek are being reviewed by the staff and licensee (Section 1.2).
The licensee had not established a margin for stem lubrication
degradation.
The licensee plans to utilize the trend analysis program to establish whether a margin is necessary (Section 1.2).
Calculated thrust requirements were more conservative than those based
on tha standard industry thrust equation as a result of use of the thrust equation developed by the Electric Power Research Institute (Section 1.2).
The licensee had satisfactorily demonstrated the short-term operability
of the seven motor-operated valves selected for review.
Some motor-operated valves will require additional evaluation including justification of the two-stage approach in order for future close out under the generic letter (Section 1.3).
Many strengths were identified in the area of design-basis testing,
including a high percentage of motor-operated valves tested at differential pressure' conditions, testing at near the maximum expected differential pressure, testing under degraded voltage conditions, and the establishment of a rigorous testing sequence.
The strengths are considered indicative of the licensee's commitment to establish an
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excellent motor-operated valve program (Section 1.3).
Several instances of incorrect and nonconservative use of the VOTES 2.3
software were identified, though no. safety-related concerns resulted (Section 1.3).
The licensee had not identified and investigated several. anomalies
apparent in the diagnostic traces. They appeared to have established such a high threshold for the identification of trace abnormalities that
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potential motor-operated valve problems could be masked (Section 1.3).
The licensee did not record motor terminal voltage during testing. The
inspectors considered this information useful but not necessary for the evaluation of motor-operated valve performance (Section 1.3).
The licensee's justification for its use of a linear extrapolation of
differential pressure' test data had not been completed (Section 1.3).
The licensee had satisfactorily demonstrated the interim operability
status of motor-operated valves that could not be tested near the maximum expected differential pressure. Additional justification will be needed to satisfy commitments to the generic letter (Section 1.3).
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The licensee had not addressed normally-open valves and had deferred
modifications to valves that may be susceptible to pressure locking and thermal binding (Section 1.4).
The licensee has not providtd justification for the use of static tests
for periodic verification (Section 1.5).
The licensee was in the process of implementing a trending program for
the Generic Letter 89-10 valves (Section 1.6).
Summary of Inspection Findinas:
Inspection Followup Item 482/9302-01 was opened (Section 1.2).
- Inspection Followup Item 482/9302-02 was opened (Section 1.2).
- Inspection Followup Item 482/9302-03 was opened (Section 1.3).
- Inspection followup Item 482/9302-04 was opened (Section 1.3).
- Inspection Followup Item 482/9302-05 was opened (Section 1.3).
- Inspection Followup Item 482/9302-06 was opened (Section 1.4).
- Inspection Followup Item 482/9302-07 was opened (Section 1.5).
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Violation Item-I.A of EA 91-161; Example (1) of Apparent Violation
482/9134-02 was closed (Section 2.1).
Violation Item I.B of EA 91-161; Example (2) of Apparent Violation
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482/9134-02 was closed (Section 2.2).
- Violation Item II.A. of EA 91-161; Example (4) of Apparent Violation
482/9134-02 was closed (Section 2.3).
Attachments Attachment 1 - Persons Contacted and Exit Meeting
Attachment 2 - Wolf Creek Gate Valve Data
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S-4-DETAILS 1 GENERIC LETTER (GL) 89-10 " SAFETY-RELATED MOTOR-OPERATED VALVE [MOV)
TESTING AND SURVEILLANCE" (2515/109)
On June 28, 1989, the NRC issued GL 89-10, which requested licensees and construction permit holders to establish a program to ensure that switch-settings for safety-related M0Vs were selected, set, and maintained properly.
Subsequently, four supplements to the GL have been issued and one issued for comment. NRC inspections of licensee actions implementing commitments to GL 89-10 and its supplements have been conducted based on guidance provided in Temporary Instruction (TI) 2515/109, " Inspection Requirements for Generic Letter 89-10, Safety-Related Motor-0perated Valve Testing and Surveillance."
Instruction TI 2515/109 is divided into Part 1, " Program Review," and Part 2,
" Verification of Program Implementation." The TI 2515/109 Part 1 program review was conducted at Wolf Creek November 4-8, 1991, and is documented in NRC Inspection Report 50-482/91-34. A followup Part 1 inspection was conducted August 24-28, 1992, and is documented in NRC Inspection
Report 50-482/92-15. The inspection documented by this report was the initial inspection at Wolf Creek under Part 2 of TI 2515/109 and, thus, was focused on verification of program implementation.
Nevertheless, programmatic issues were addressed during this inspection in response to followup of findings in the Part 1 inspection and in the context of issues that developed in the course of this inspection.
As an overall assessment, the inspectors concluded that the licensee's MOV program was capable of successfully demonstrating the capability of the MOVs subject to GL 89-10. The program appeared to acceptably implement the licensee's commitments to the GL. As a general observation, the inspectors noted an extensive quality control involvement in the entire MOV program.
The principal focus of the inspection was to select and review in depth several MOVs from the GL 89-10 program. The selection was based on an information matrix provided by the licensee in response to a request by the inspectors.
The selection was biased toward MOVs that appeared to have less than average margin; otherwise, an attempt was made to select various sizes and differential pressure conditions.
For each MOV selected, the inspectors reviewed the design basis calculation of the maximum expected differential pressure (MEDP), the sizing and switch setting calculation, the diagnostic test data package, and the diagnostic traces using V0TES 2.3 software. The following MOVs were selected for review:
BBHV0013 Reactor Coolant Pump A Thermal Barrier CCW Return Isolation BGHV8105 Charging Pumps to Regenerative Heat Exchanger / Containment Isolation EJFCV0610 Residual Heat Removal Pump A Miniflow Control
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EJHV8716A Residual Heat Removal Pump A to Safety Injection Hot Leg Recirculation Loops 2 and 3 Isolation EMHV8803B Charging Pump Discharge Header to Boron Injection Tank Isolation EMHV8807A Residual Heat Removal Heat Exchanger A/ Chemical and Control Volume System to Safety Injection Pumps A and B Suction BBHV8000B Pressurizer Power-0perated Relief Valve Block Valve The selected MOVs were gate valves and were configured as shown below:
Actuator Closure Control Valve Size (inches)
BBHV0013 SMB-00 TORQUE
BGHV8105 SB-00 LIMIT
EJFCV0610 SMB-000 TORQUE
EJHV8716A SB-1 TORQUE
EMHV8803B SBD-00 LIMIT
EMHV8807A SB-00 TORQUE
BBHV80008 SB-00 LIMIT
1.1 Desian-Basis Reviews The inspectors reviewed the calculations determining the MEDP, design-flow
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conditions, design temperature, and other design parameters for each of the MOVs selected for review.
For each M0V determined to be capable.of being mispositioned, the worst case differential pressure in either the open or closed direction was assigned as the MEDP in both directions. The inspectors concluded that the design-basis reviews were comprehensive and conservative.
1.2 M0V Sizina and Switch Settina The inspectors reviewed the MOV Program Description WCN0C-85, Revision 2, April 30, 1993, and the Wolf Creek NRC GL 89-10 Motor-Operated Valve Summary Package Program Plan for the seven selected MOVs.
Each document included the design basis calculation of the MEDP (discussed above), thrust and torque calculations, test requirements, dynamic test results, and the verification of assumptions.
The inspectors reviewed calculations estimating the thrust and torque requirements and requisite switch settings for each of the seven MOVs selected for review.
The inspectors noted that, in general, these calculations were more conservative than the standard industry equation for the same valve friction assumption. This resulted from the use of the Electric Power Research Institute thrust equation in lieu of the standard industry equation.
The Electric Power Research Institute equation contains all of the terms of the standard equation, but includes other factors that tend to-increase the
.l calculated thrust requirements. A disc friction coefficient of 0.50 was assumed and used in 'the gate valve thrust equation.
The licensee also assumed j
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-6-a stem friction coefficient of 0.20.
The thrust requirements were adjusted to account for diagnostic equipment inaccuracies (including torque correction factor) and torque switch repeatability.
The inspectors noted that the licensee had not established a margin in its MOV
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thrust calculations to account for rate-of-loading (load sensitive behavior)
effects.
The licensee stated that the effects of rate-of-loading had been accounted for by assuming a conservative assumption for stem friction coefficient of 0.20.
Based on preliminary results, the licensee had observed an average stem friction coefficient of 0.10, with a range between 0.08 and 0.22.
The inspectors concluded that the licensee's substitution of a conservative stem friction assumption for rate-of-loading was potentially acceptable for limit-closed MOVs as long as this assumption was validated to bound the stem friction experienced at design basis conditions.
Based on the preliminary results, it appeared that the licensee may be able to establish that a 0.20 stem friction coefficient is conservative.
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For torque-closed MOVs, however, the inspectors determined that the lack of a margin for rate-of-loading may be nonconservative for certain MOVs, regardless of the value of the stem friction.
The additional thrust capability afforded by a low stem friction coefficient is not available to a torque-closed M0V.
The stem friction experienced under static conditions may not correspond to the stem friction under differential pressure conditions and the action of the torque switch may be different under the varying rate at which the springpack is compressed. These two effects could combine to result in the effect of having a lower amount of thrust applied to the stem at torque switch trip
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under dynamic conditions than under static conditions. This is typically considered a " positive" rate of loading condition. The inspectors were concerned that a positive rate of loading condition could adversely affect the operability of Valve BBHV0013. This valve had only a 3 percent margin between the thrust at control switch trip and the thrust necessary to close the valve when its test at very low differential pressure conditions (70 psid verses a 2291 psid MEOP) was extrapolated to design conditions.
However, the licensee had observed mostly " negative" rate-of-loading during testing. The calculated rate-of-loading had ranged from -268 percent to +18 percent with an average of-11 percent.
This indicated that on average the thrust at torque switch trip was greater under dynamic conditions than under static conditions.
The inspectors observed that the valves selected for this inspection showed a general tendency for a " negative" rate-of-loading condition (see Attachment 2 under column for load sensitive behavior). The inspectors and the licensee i
agreed that this was unusual in light of test results from other facilities that has generally shown a preponderance of " positive" rate-of-loading. The dynamic testing at Wolf Creek is performed at degraded voltage, as discussed in Section 1.3.
The effect of degraded voltage operation on rate-of-loading has not been established.
The inspectors concluded that an immediate operability concern did not exist for Valve BBHV0013 because of the prevailing observation of " negative" rate-of-loading and other conservatism that were inherent in the calculation of required thrus '
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However, several long-term issues were identified that will need to be addressed.
First, the licensee will need to provide additional justification for the exclusion of a rate-of-loading margin for torque-closed MOVs.
Second, if a " positive" bounding rate-of-loading assumption is determined to be statistically indicated, then the licensee would need to revisit the test results of Valve BBHV00013 and other marginal torque-closed MOVs to determine if conservatism in the calculations are sufficient to still consider the valves operable.
Third, following the reduction of the test data for the current outage, the staff plans to have discussions with the licensee to review the rate-of-loading test results. These issues were identified as an inspection followup item (482/9302-01).
The inspectors noted that the licensee had not established a margin to account for stem lubrication degradation. Over a typical 18-month operating cycle, the grease applied to the valve stem may tend to harden or become impregnated with dust or other debris. The overall effect is to increase the stem factor (and stem friction coefficient) resulting in less thrust delivered to the stem for any given amount of applied torque. At this time, there is very little test data in the industry to quantify the effects of stem lubrication degradation.
Some licensees have made interim assumptions in the range of 5 to 10 percent to account for this phenomenon, though'it is possible that for
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certain configurations and lubricants, the degradation may be negligible. The licensee stated that the-trend analysis program now in place will evaluate for-the effects of stem lubrication degradation and that. appropriate margins will be established if they were indicated by the trending results. This issue was identified as an inspection followup item (482/0302-02).
1.3 Desian-Basis Ca.p_a.bility The inspectors reviewed the diagnostic test data packages, dynamic test requirements, test results, the verification of assumptions documented in the Wolf Creek NRC GL 89-10 Motor-0perated Summary Package Program Plan, and the V0TES 2.3 diagnostic traces for each of the seven MOVs selected for review.
On the basis of this review, the inspectors concluded that the licensee had
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satisfactorily demonstrated the short-term capability of these MOVs, recognizing that in some cases the licensee will need to perform additional
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evaluation of their two stage approach in order to fully address the GL.
The dynamic tests reviewed were conducted under the following conditions:
BBHV0013, 3%/3% of Opening / Closing Design-Basis Differential Pressure BGHV8105, 89%/89% of Opening / Closing Design-Basis Differential Pressure EJFCV0610, 97%/97% of Opening / Closing Design-Basis Differential Pressure EJHV8716A, 52/93% of Opening / Closing Design-Basis Differential Pressure-EMHV8803B, 85/99% of Opening / Closing Design-Basis Differential Pressure EMHV8807A, 78/80% of Opening / Closing Design-Basis Differential Pressure Valve BBHV8000B was tested under static conditions only.
The inspectors identified several strengths in the area of design-basis testing. Of the 52 MOVs addressed during Refueling Outage VI, the licensee I
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t-8-had tested or had planned to test 42 at differential pressure conditions. The inspectors considered this to represent a commendably high percentage of differential pressure tests. Additionally, most of the tests were performed at differential pressures near or above 80 percent of the MEDP.
Of the.37 differential pressure tests that had been completed at the time of the inspection, only 5 had been conducted at a differential pressure of less than 72 percent of the MEDP in the closed direction. This fact indicated that the licensee was aggressively pursuing an optimal simulation of design-basis conditions. This strength was reinforced by the fact that every differential
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pressure test was conducted under degraded voltage conditions, a testing configuration that is very unusual in the nuclear industry. The degraded voltage was established by applying 92 percent of 460 volts (equalling the
design degraded voltage condition with the potential exception of temperature-related cabling voltage losses) to the motor control center of each MOV tested under differential pressure conditions.
An additional strength, in the area of MOV testing, was the establishment of a rigorous testing sequence for each M0V, including an as-found static test, a refurbishment of the actuator, a set-up test (to set the switches), a dynamic test at reduced voltage (for 42 of 52 valves), a baseline static test, and an as-left static test. Torque was monitored on both the dynamic and baseline i
static test using the V0TES torque cartridge (VTC).
The as-left test was performed after removal of the VIC to ensure that the actuator operation was
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not affected, since the VTC is an intrusive device.
The inspectors considered'
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this testing sequence to represent an improved methodology for conducting V0TES testing.
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s The preliminary results of the existing test data revealed disc friction coefficients in the range of 0.02 to 0.78 in the opening direction and 0.05 to
0.77 in the closing direction.
Stem friction coefficients were between 0.08 i
to 0.22.
The valves reviewed during this inspection had closing disc frictico coefficients in the range of 0.17 to 0.55 and stem friction coefficients between 0.08 and 0.20 (see Attachment 2). M0V EJFCV0160 had a disc friction
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coefficient of 0.55, which was greater than the assumed disc friction coefficient of 0.50, however, the valve had adequate margin.
The licensee was in the process of revising the design basis calculations to reflect the dynamic test results.
During the review of the dynamic test packages, the inspectors noted that.the
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licensee had calculated thc stem factor and stem friction coefficient at various points of the valve stroke.
In addition, disc friction coefficients were calculated in both the opening and closing direction (see Attachment 2).
These test results will be incorporated into the licensee trending program.
The inspectors performed a detailed review of diagnostic traces using the
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VOTES 2.3 software for each of the seven M0Vs selected for review. Several discrepancies were noted. On the differential pressure trace of
Valve EJHV8716A, the marking of point C5, running load near the end of the
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stroke, was incorrect. The C5 mark had been placed concurrent with the mark for point Cll, seat contact. At this point, considerable flow effects are
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present which tend to overshadow the running load.
By marking point C5 at seat contact, the V0TES software computed a higher average running load than was actually present.
Since the average running load is subtracted from the maximum thrust prior to disc wedging in the process of extrapolating test results to the design basis condition, the erroneous mark for point C5 was nonconservative.
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In this case, the extrapolation was of a small magnitude and the difference in extrapolated thrust to close the valve was minor.
Valve EJHV8716A had sufficient margin to account for this slight change in thrust requirements.
The licensee stated that all necessary corrections would be made to the test evaluation for this valve. An identical problem was identified on the -
differential pressure trace of Valve BGHV8105. Once again, sufficient margin existed and the licensee stated that corrections would be made. The inspectors determined that the marking of point C10, flow cutoff, on the differential pressure trace of Valve EMHV8807A was nonconservative. The mark for C10 had been placed concurrent with the mark for point Cll, seat contact.
However, in the last 1/2 second prior to seat contact, the stem force was
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t approximately 100 to 200 pounds higher than at seat contact. The test results implied that this additional force would be necessary to close the valve and that, therefore, the selected point for C10, which did not account for this force, was nonconservative. The licensee concurred that the C10 mark in this case was not in the proper position and stated that the trace would be corrected. Sufficient margin existed to account for the additional required force. The licensee indicated that additional training in the use of the
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VOTES 2.3 software would be conducted. The licensee also stated that other traces would be reviewed to identify other similar problems. This issue was identified as an inspection followup item (482/9302-03).
During review of the same differential pressure diagnostic traces, the inspectors identified several apparent anomalies that had not been identified and documented in the post-test analysis process.
Examples included an
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unusual spike in the closing torque trace of Valve EJHV8716A, unexplained
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noise in the opening thrust trace of Valve EJFCV0610 that did not start until the valve was 70 percent open, lack of correlation between the closing trace of torque and worm displacement for Valve BBHV8000B, an apparent (though not actual as confirmed by other sensors) bottoming of the springpack during the closing trace of Valve EMHV8803B, and cyclic loading with a peak-to-peak magnitude of 20 percent of the measured thrust on Valve BGHV8105. None of the anomalies mentioned above suggested an immediate operability concern.
However, the failure to identify and determine the cause of these unusual
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features may represent a missed opportunity to identify and correct an early indication of a potential problem. The inspectors considered the licensee's threshold for identifying unusual conditions or anomalies on diagnostic traces to be high. The licensee indicated an intention to review the anomalies
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discussed by the inspectors and to pay additional attention to this area in the future. Additionally, the licensee stated that within the framework of
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the trend analysis program, traces resulting from periodic verification of valve performance (nominally every 5 years for every valve) would be compared
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to the previous trace to detect any differences. This comparison may'be
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-10-restricted to static traces since the current plan was to conduct only static testing for the purposes of periodic verification. This issue was identified as an inspection followup item (482/9302-04).
During testing of M0Vs at dynamic conditions, the licensee had reduced the voltage of the motor control center to simulate worst-case voltage conditions, but did not record the voltage at the MOV terminals. The licensee justified this based on the inability to simulate the worst-case conductor temperature of 180 C, used in the calculations, and the fact that voltage at the motor control center was reduced to a value that would bound the worst-case design-basis motor control center voltage. The inspectors considered the measurement of motor-terminal volttge to be potentially useful, but not necessary to demonstrate M0V capability. The licensee stated that a deliberate decision had been made to delete this measurement on the basis of a cost-benefit consideration.
Where testing could not be practically conducted at design-basis conditions, the licensee utilized a straight-line extrapolation of the thrust to overcome differential pressure using the ratio of design-basis differential pressure to the test differential pressure. According to WCNOC-85, when differential pressure testing is conducted at less than 80 percent of the MEDP, multi-point testing would be conducted to verify the extrapolation method. However, the licensee had subsequently determined that multi-point testing was not practical at Wolf Creek. Therefore, the inspectors considered the licensee's extrapolations to design-basis conditions to be the first stage of a two stage approach where the valves have been set up using the best available data, as discussed in GL 89-10.
The licensee will be expected to justify its method of extrapolation by the schedule commitment date for the completion of their GL 89-10 program.
The inspectors reviewed the licensee's' documented margin analysis of those valves that were not scheduled for differential pressure testing. This analysis included consideration of limit closure, stem friction coefficient and disc friction coefficient assumptions, observed rate-of-loading on similar valves, conservatism in the thrust calculations, observed inertial effects, and other considerations.
The inspectors concluded that the licensee had sufficiently demonstrated the interim capability of this subset of MOVs, though additional justification will be necessary to close out these MOVs and others that will not be tested at or near MEDP conditions under the two-stage approach discussed in GL 89-10. An inspection to close out TI 2515/109 Part 2 will be conducted to review the disposition of valves that can be tested only under static conditions or at low differential pressures. This is identified as an inspection followup item (50-482/9302-05).
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1.4 Pressure lockina and Thermal Bindina The Office for Analysis and Evaluation of Operational Data (AE00) has completed a study of pressure locking and thermal binding of gate valves.
AE0D concluded in its report that licensees have not taken sufficient action to provide assurance that pressure locking or thermal binding will not prevent a gate valve from performing its safety function. The NRC regulations require that licensees design safety-related systems to provide assurance that those-systems can perform their safety functions.
In GL 89-10, the staff requested licensees to review the design bases of their safety-related MOVs.
The inspectors reviewed the licensee's evaluations of the potential for pressure locking and thermal binding of gate valves as part of their design basis review. The licensee had completed a review of their valves which are subject to pressure locking and thermal binding and could be expected to open in the event of an emergency. Their initial search identified two valves which were potentially susceptible to pressure locking or thermal binding.
The licensee had prepared modification packages for the two valves, but since they had shown no previous signs of pressure locking, the licensee had postponed the modifications pending further consideration.
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f Although the licensee had addressed normally closed valves, the inspectors questioned whether pressure locking had been analyzed for any normally open
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valves.
The licensee was unable to provide documentation that normally open
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valves had been sufficiently evaluated in the event of maintenance,
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surveillance, or testing activities which might preclude the restoration of
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these valves for a long period of time. The evaluation of normally open valves and the deferral of valve modifications will be reviewed during a
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future inspection and has been identified as inspection followup item (50-482/9302-06).
1.5 Periodic Verification of MOV Capability During the GL 89-10 Part 1 inspection, the licensee had not yet established a methodology for periodically verifying MOV performance. The licensee had since established that periodic testing will consist of an as-found static test performed at intervals for the purpose of tracking, t ending, and analyzing MOV performance under the preventive maintenance program. The licensee will need to provide additional justification for the use of static periodic tests. This is a generic issue that will La reviewed by the NRC when
additional informatioi, becomes available. This is considered to be an inspection followup item (50-482/9302-07).
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1.6 MOV Failures. Corrective Actions. and Trendina During the GL 89-10 Part 1 inspection, the licensee was using existing plant programs to identify and correct MOV failures. During this inspection, the inspectors reviewed the licensee's progress in developing a trending system specifically for the GL 89-10 MOVs.
The licensee had issued Procedure WCNOC-86, "MOV Tracking and Trending," Revision 1.
This procedure
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-12-contained guidelines to collect and maintain data of MOVs in order to track and trend their performance, enhance their reliability, and schedule optimum preventive maintenance frequencies by analyzing and anticipating potential degradation. The licensee was in the process of entering applicable test data and parameters to be trended into the software developed for this purpose. The full implementation of this procedure will be reviewed during a future inspection.
2 FOLLOWUP ON CORRECTIVE ACTIONS FOR VIOLATIONS (92702)
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2.1 (Closed) Violation Item I.A of EA 91-161; Example (1) of Apparent Violation 482/9134-02: Corrective Actions for M0Vs NRC Inspection Report 50-482/91-34 documented that the licensee did not take prompt corrective action regarding significant conditions adverse to quality.
This issue involved the failure to properly disposition five M0Vs that appeared potentially incapable of performing their safety functions.
In February 1991, records indicated that licensee personnel had identified that these five MOVs might not be capable of performing their safety functions based on minimum voltage assumptions and other concerns. However, the licensee did not appropriately address the identified potential deficiencies.
In November 1991 and January 1992, upon further review of the same deficiencies, the licensee determined that the motor operators for four of these five valves were incapable of operating their associated valves under design basis conditions.
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The licensee subsequently replaced each of the four Limitorque actuators with a larger actuator. After replacement of the actuators, testing was performed
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to confirm that torque / thrust requirements were satisfactory. Additionally, the licensee evaluated the cause for the original installation of the
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undersized actuators and in the process identified other MOVs that could be similarly affected. Calculations to determine torque / thrust requirements versus capabilities were performed for the MOVs with any deficiencies resolved prior to startup following the fifth refueling outage.
2.2 (Closed) Violation Item I.B of EA 91-161; Example (2) of Apparent Violation 482/9134-02: Corrective Actions for MOVs
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NRC Inspection Report 50-482/91-34 documented that the licensee did'not take prompt corrective action regarding significant conditions adverse to quality regarding audit findings that indicated significant weaknesses in the
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licensee's MOV program.
Following a May 1991 independent audit of its M0V program by a contractor, which indicated significant weaknesses in the licensee's MOV program, the licensee took no tangible action to evaluate and disposition the weaknesses identified in the audit.
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The licensee conducted interviews with individuals responsible for the M0V _
program to determine if they held a correct perception of their responsibility to report problems. Management found that accurate and favorable responses were in the majority. Additionally, other GLs, bulletins and related industry
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items were reviewed for similar programmatic concerns.
Purchase orders were reviewed to determine if other contractor-performed reports were in existence where concerns were raised which had not been addressed.
No outstanding safety concerns were identified.
Procedure KGP-1201, " Corrective Action," was developed and implemented for controlling line organization self-assessment,
whether performed internally or by contract. This procedure was developed to ensure that line management effectively uses the self-assessment process to
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monitor performance.
The licensee conducted training on the new procedure in conjunction with revised Procedure KGP-1210, " Performance Improvement
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Requests."
Improvements in the MOV program accomplished over the past year were verified during this inspection to have addressed the weaknesses that had been identified in the May 1991 contractor audit.
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2.3 (Closed) Violation Item II.A. of EA 91-161: Example (4) of Apparent Violation 482/9134-02: Corrective Actions for MOVs NRC Inspection Report 50-482/91-34 documented that the licensee did not take adequate corrective action to ensure that a significant condition adverse to
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quality did not exist with respect to a safety-related MOV that had been subjected to a thrust load in excess of its maximum qualified thrust.
Following a significant overthrust of Valve BBHV8000B, power-operated relief valve block valve in October 1991, the licensee did not follow the manufacturer's guidelines for evaluating the condition of the valve and actuator internal parts to determine any effects on MOV operability.
In response to the violation, the licensee re-evaluated the overthrust i
condition, which included identifying the stress level, the number of overthrust cycles, and the weak link node of failure. The MOV actuator was disassembled and an inspection was conducted to determine if any damage had occurred due to the overthrust condition. The licensee concluded that the
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overthrust condition did not damage the M0V. The licensee also determined that the cause of the overthrust condition was a misunderstanding of the function of the actuator, resulting in an improper method of establishing the
correct compensator spring settings. The licensee identified 16 MOVs impacted by this misunderstanding and resolved these deficiencies prior to startup following the fifth refueling outage. The licensee also re-evaluated previous dispositions involving the overthrust of MOVs and resolved all discrepancies
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prior to startup.
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ATTACHMENT 1 1 PERSONS CONTACTED 1.1 Licensee Personnel
- R. Benedict, Manager, Quality Control
- J. Black, Motor-Operated Valve Team, Operations
- M. Dingler, Manager, Nuclear Plant Engineering - Support
- R. Flannigan, Manager, Nuclear Plant Engineering - Support
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- C. Fowler, Manager, Maintenance and Modifications
- K. Fullen, Motor-0perated Valve Engineer
- R. Hagan, Vice President, Nuclear Assurance
- C. Hernandez, Motor-0perated Valve Engineer
- D. Hooper, Engineering Specialist, Licensing
- W. Lindsay, Manager, Quality Assurance
- G. Maphiir, Motor-0perated Valve Team, Electrical Engineer
- 0. Maynard, Vice President, Plant Operations
- K. Moles, Manager, Regulatory Services
- K. Powell, Scheduler, Motor-0perated Valve Team
- L. Ratzlaff, Supervising Engineer
- R. Reitman, Motor-0perated Valve Team
- F. Rhodes, Vice President, Engineering
- C. Rich, Supervisor, Electrical Maintenance
- T. Riley, Supervisor, Regulatory Compliance
- C. Sprout, Manager, System Engineering
- H. Stubby, Supervisor, Technical Training
- D. Swarigan, Motor-0perated Valve Engineer
- J. Tarr, Regulatory Compliance Engineer
- D. Weninger, Motor-0perated Valve Engineer 1.2 NRC Personnel
- G. Pick, Senior Resident Inspector In addition to the personnel listed above, the inspectors contacted other personnel during the inspection.
- Denotes personnel that attended the exit meeting.
2 EXIT MEETING
'I An exit meeting was conducted on May 7, 1993. During this meeting, the inspectors reviewed the scope and findings of the report. During this meeting, the licensee. identified as proprietary the design basis calculations provided to the inspectors for review during the inspection and copies of this material provided for further reference. No proprietary information was discussed in this inspection report.
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ATTACHMENT 2 WOLF CREEK GATE VALVE DATA Diagnostics: VOTES System with VTC for Torque Measurements VALVE VALVE SIZE TEST DISC STEM IDAD" NUMBER
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CONDITIONS FRICTION FRICTION SEN9TIVE MANUFACTURER COm1CIFNT CO m 1CIENT BEIIAVIOR BBHV0013 3*
68 psid (Close)
0.17 (Close)
0.16-8.0 %
VELAN 68 psid (Open)
(No Data)
BGHV8105 3"
2670 psid (Close)
0.47 (Close)
0.18 Limit Closed Westinghouse 2670 psid (Open)
0.02 (Open)
EJFCV0610 3"
197 psid (Close)
0.55 (Close)
0.09-12.1%
Westinghouse 197 psid (Open)
0.44 Close)
EMHV8807A 6'
196 psid (Close)
0.29 (Close)
0.20-1.0 %
Westinghouse 191 psid (Open)
0.33 (Open)
EJIIV8716A 10" 226 psid (Close)
0.51 (Close)
0.14 6.4 %
Westinghouse 224 psid (Open)
0.33 (Open)
J EMilV8803B 4*
2682 psid (Close)
0.24 (Close)
0.10 1.2 %
Westinghouse 2682 psid (Open)
0.11 (Open)
- The dynamic disc friction coefficients listed were calculated by the licensee using a mean seat diameter.
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A negative number indicates that the thrust observed at CST during the dynamic test was greater than the thnist observed at CST during the static test.
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