IR 05000237/1993021
| ML17179B088 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/14/1993 |
| From: | Dunlop A, Jeffrey Jacobson, Samson Lee, Replogle G, James Smith NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17179B087 | List: |
| References | |
| 50-237-93-21, GL-89-10, NUDOCS 9309210158 | |
| Download: ML17179B088 (13) | |
Text
U. S. NUCLEAR REGULATORY COMMISSION
REGION III
Reports No. 50-237/9302l(DRS); No. 50-249/9302l(DRS)
Docket No ; 50-249 Licenses No. DPR-19; No. DPR-25 Licensee:
Commonwealth Edison Company Executive Towers West III 1400 Opus Place, Suite 300 Downers Grove, IL 60515 Facility Name:
Dresden Nuclear Power Station - Units 2 and 3 Inspection At:
Dresden Site, Morris, Illinois Inspection Conducted:
August 2-6 and 16-19, 1993
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Inspection conducted August 2-6 and 16-19, 1993 (Reports N /9302l(DRS); No. 50-249/9302l(DRS))
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Date Areas Inspected:
Announced safety inspection of the implementation of the licensee's response to Generic Letter (GL) 89-10, "Safety-Related Motor-Operated Valve (MOV) Testing and Surveillance" (2515/109).
Results:
The inspection disclosed significant weaknesses in the implementation of the GL 89-10 progra The overall lack of testing progress and weakly supported technical assumptions is an indication of weak management oversight.
9309210158 930916 PDR ADOCK 05000237 G
Inspection Summary
The licensee demonstrated strengths in the following areas:
0 Several research type testing initiatives were sponsored, such as the roller bearing stem nut testing program and the testing program to evaluate the capabilities of AC motor The self-assessment, dated January 25, 1993, was thorough and helped to focus management's attention on deficiencies in the MOV program, although many major weaknesses remaine The licensee demonstrated weaknesses in the following areas:
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Little progress was made in the development of a site specific program documen Differential pressure (dp) testing efforts were minimal and tests were not performed as schedule These efforts were believed to be among the weakest in the countr Technical assumptions were not appropriately justifie The commitment tracking system did not appear to be effective, either at the corporate or site levels.
Little work was performed to address the potential for gate valve pressure locking and thermal bindin Modifications, to remove deficiencies in some "Supplement-3" MOVs, were not performed in a timely manne Limit switches for two CCSW MOVs (3-1501-3A and 3-1501-38, containment cooling heat exchanger discharge valves) were inappropriately set based on an inaccurate dial indicator and contributed to the degraded state of the Unit 3 CCSW syste Additionally, the valve expert, with knowledge of the limit switch configuration, was only asked to consult about the problem recently, as opposed to when problems were first noticed (over one year ago).
DETAILS Persons Contacted Commonwealth Edison Company (CECo)
- H. Massin, Site Engineering and Construction (SEC) Manager
- B. Adams, Regulatory Assurance
- P. Dietz, Mechanical and Structural Engineering Programs Supervisor
- B. Gurley, NRC Coordinator
- W. Kapunus, Maintenance Engineer
- H. Mulderink, Corporate MOV Coordinator
- J. O'Neil, SEC Programs Lead
- E. Rowley, Site Engineering
- J. Shields, Regulatory Assurance Supervisor
- J. Williams, SEC Plant Support Engineering Supervisor U. S. Nuclear Regulatory Commission (NRC)
- G. Wright, Chief, Engineering Branch
- J. Jacobson, Chief, Materials & Processes Section
- A. Stone, Resident Inspector
- Denotes those attending the exit meeting on August 19, 1993. Licensee Action on Previous Inspection Findings (92701)
(Closed) Inspection Followup Item 50-237/91011-0l(DRS); 50-249/91010-01:
This item concerned the use of nominal reactor pressure to determine at what pressure a high energy line break (HELB) can be assumed for determining the worst case design basis conditions for MOVs (Branch Technical Position (BTP)
SPLB 3-1).
Based on consultation with NRR, it was concluded the worst case differential pressure (dp) used for evaluating MOVs and for MOV sizing calculations should be the maximum reactor pressure (first relief valve setpoint) and not nominal reactor pressur The licensee made appropriate corrections to the calculations based on the guidance from NR The inspectors performed a review of selected dp calculations in the high pressure coolant injection and isolation condenser systems and confirmed that the appropriate actions were take This item is close.0 Inspection of the Implementation of the Program Developed in Response to Generic Letter 89-10 To address concerns about the program guidance, noted in previous NRC reports at other CECo sites and in the licensee's self-assessment, dated January 25, 1993, the licensee decided to reconstitute the program guidance and develop a site specific program documen However, little progress had been made toward accomplishing this goa Considering the length of time that the program documentation has remained an issue, the inspectors judged the lack of progress in this area to be an indicator of poor management oversight of the program.
3.1 Design Basis Reviews 3. Differential Pressure and Flow Requirements The inspectors reviewed the licensee's design basis maximum expected differential pressure calculations and found them to be acceptabl.1. 2 Degraded Voltage Calculations The licensee corrected deficiencies in the degraded voltage calculations, which were noted during a previous NRC electrical distribution system functional inspection (Reports No. 50-237/91038 and No. 50-249/91042).
The previous calculations assumed an inappropriate grid voltage, and were not based on a voltage corresponding to the second level under-voltage relay setpoin The corrected calculations appeared to be acceptabl.2 MOV Switch Settings Sufficient steps were not taken to justify generic programmatic assumptions used to determine torque switch settings such as, valve factors, stem friction coefficients, load sensitive behavior, and degradatio For example, the CECo program assumed valve factors to be 0.3 for untested flex wedge gate valves, although approximately 75% of the gate valves tested, CECo wide, had valve factors greater than Furthermore, the program did not account for load sensitive behavior, although most of the tested MOVs exhibited some load sensitive behavio The inspectors considered the minimal work toward the justification of generic program assumptions to be a weakness.
The limit switches for two Unit-3 component cooling service water (CCSW)
valves (3-1501-3A and 3-1501-38, containment cooling heat exchanger discharge valves) were inappropriately set based on inaccurate position indicator The position indicators, supplied with the actuator, were originally intended to be used as a gross means of determining valve position, not accurate position indicatio As a result of the misuse of the indicators, the MOVs did not fully open and partially restricted flo This condition contributed to the degraded condition of the CCSW syste To cor-rect the condition, the licensee ordered new position indicators, with a more appropriate range, and.agreed to set the limit switches in a manner in which the valves can be verified fully ope The licensee's corrective actions appeared to be appropriate and will be reviewed during a future inspectio Although the licensee believed that at least one of the subject CCSW valves had a partial blockage approximately one year prior to the discovery of the limit switch problem, the valve expert, who was knowledgeable of the limit switch configuration, was only contacted recently (during this inspection).
The poor limit switch setting practices and tne failure to involve the appropriate experts at the initial stages of problem solving was considered to be a weaknes The aspect of the degraded CCSW system is part of a larger CCSW issue and will be handled by the NRC resident inspection staff.
- Schedule The expected completion date for the licensee's program was well beyond the original recommendations contained in Generic Letter (GL) 89-1 The GL stated that each licensee should complete applicable recommendations within 5 years or 3 refueling outages of the date of the GL, whichever was late In a letter to the NRC dated September 28, 1990, the licensee committed to perform the recommendations for all "Priority l valves by the end of the third refueling outages beginning with the spring 1991 outage CECo had previously determined that all GL 89-10 valves at Dresden would be treated as Priority I valve The NRC accepted the schedule in a letter dated January 23, 199 However, according to a NRR/MEB representative, part of the basis for the acceptance was that the first refueling outages were expected in the spring of 1991 and the third refueling outages were expected to occur during the spring of 1994 - somewhat consistent with the GL recommendation The final (third) refueling outages for Unit 2 and Unit 3 are now expected to be in the fall of 1996 and the fall of 1995, respectivel The reasons for the late completion dates included: The first applicable outage for Unit 2 did not begin until January 1993 (not spring 1991). The first applicable outage for Unit 3 was actually September 1991 to April 199 Several forced outages caused the delay of the scheduled refueling outage The NRC inspectors consulted with NRR concerning the progress of the program and the lengthy schedul The NRC staff consensus was that the licensee had not taken proactive steps to complete the program in a timely manner and had failed to perform a significant amount of work during the several forced outages and lengthy refueling outage NRR indicated that the licensee's schedule would be reconsidere MOVs were scheduled for dp testing, but the licensee has not demonstrated an ability to perform scheduled testin For example, approximately 15 MOVs were scheduled to be dp tested during the most recent refueling outage on Unit 2; however, only two dp tests were actually performe The inspectors considered the failure to perform scheduled testing to be an indicator of weak management oversigh This issue will be reviewed during a future inspectio.4 Design Basis Capability 3. Differential Pressure Testing The licensee had only performed a minimal number of dp tests (two) at the time of the inspectio The minimal effort did not seem justified considering that several forced outages and lengthy refueling outages (one on Unit 3 lasting eight months) provided additional opportunity for the testin The inspectors performed an informal survey of the progress of other utilities and found that
the licensee's efforts were among the weakes Furthermore, additional dp testing would not be accomplished until the spring of 1995 for Unit 2 and spring of 1994 for Unit 3, approximately the same time that most other licensees will be expected to be finished with their testing program The failure to perform a significant amount of testing, almost four years after the issuance of GL 89-10, is an indicator of weak management oversight of the progra The inspectors reviewed the evaluations for the two dp tests and found the work to be technically sound and timel However, due to structural limitations, only torque was measured (not thrust).
Although an appropriate operability assessment was performed, the valve factors, stem friction coefficients, and effects from load sensitive behavior could not be quantifie Procedures for dp testing did not require fluid temperature measuremen The licensee agreed that taking these measurements could be beneficial and agreed to begin recording temperatures during future tests, when possibl This issue will be reviewed during a future inspectio. Valves That Will Not Be DP Tested To justify design basis capability for valves that will not be dp tested, the licensee planned to group valves and test at least 30% of the valves in each grou Data from other sources, valves outside of the Dresden facility, may also be used to supplement the ~lant specific data and to reach the 30% goa However, the grouping program was only in the initial stages - specific valves that would be tested to meet the program requirements were not selected and other implementation plans were not develope This issue will be reviewed during a future inspectio.5 Evaluation of Test Data and VOTES Traces Potential uncertainties, such as spring-pack curve accuracy and instrument uncertainty, were not considered when the test data was used to calculate the stem friction coefficient for specific MOV The failure to account for the uncertainties could result in under-predicting stem friction coefficients, effectively over predicting MOV capabilit The licensee had determined that the procedure used for the task was in need of revision and agreed to consider the inspector's comments when revising the documen This issue will be reviewed during a future inspectio The inspectors reviewed a sample of traces from the Valve Operational Test Equipment System (VOTES) and found the traces to be appropriately marked and anomalies appeared to be properly evaluate The diagnostic equipment program appeared to be acceptable.
- Periodic Verification of MOV Capability The licensee planned to use static diagnostic testing to periodically verify MOV capability and will rely on information to be provided by the BWR Owner's Group to justify the periodic verification metho A draft form of the justification document is expected in November 199 This issue will be reviewed during a future inspectio.7 MOV Failures, Corrective Actions and Trending The NRC inspectors reviewed problem reports associated with recent MOV failure The failures appeared to be properly diagnosed and corrective actions appeared to be effectiv The inspectors reviewed the actions taken to address Limitorque's May 13, 1993, Part 21 report addressing high temperature effects on AC motor The licensee presented a detailed plan to address this issue and had completed a preliminary operability assessment for the affected valve No valves were found to be inoperabl This issue will be reviewed during a future inspection when a final evaluation is availabl The licensee's program for trending failures and test data appeared to be acceptable, but did not consider all the trendable parameter The trending of test data captured the ten categories of data recommended by corporate guidance NOD-MA-I and agreed to consider trending nine additional parameters, noted in GL 89-1 This issue will be reviewed during a future inspection. Supplement 3 to Generic Letter 89-10 Supplement 3 identified potential deficiencies in certain MOVs and requested licensees to complete any necessary modifications, to correct the deficiencies, within 18 months or one refueling outage of the issue date (October 25, 1990).
The licensee did not take prompt actions to correct deficiencies in at least one valve (3-1301-3, isolation condenser return line isolation) within the scope of GL 89-10, Supplement-Although a minor gear change, performed during the September 1991-April 1992 outage, enhanced the valve's performance, the inspectors considered the MOV to be deficient and in need of further modifications to ensure operabilit The licensee now expects the necessary modifications to be performed during the spring 1994 outag In letters to the NRC dated March 11 and 21, 1991, the licensee stated that the subject valve was deficient and that appropriate modifications could not be completed within the specified time frame because of the long lead time (52 weeks) required for the delivery of the actuato Modifications were expected to be complete in October 1992 (which was later changed to March 1993).
However, the licensee did not take prompt steps to order the actuator, as evidenced by the purchase orders that were dated April 1992 (approximately the same time frame that other licensees were expected to have the deficiencies corrected).
The inspectors were concerned with the licensee's late actions because the desired modifications could have been performed during the 9/91 to 4/92 refueling outage if the parts were ordered in a timely manne Furthermore, an additional gear change, using the existing actuator, would
have further enhanced the valve capabilities and could have been performed during the 91-92 outage (although a change to the technical specification stroke time for the valve would have been required).
The failure to consider all possible alternatives for enhancement and the failure to take prompt corrective actions to address this issue demonstrates weak management oversight and a failure to appropriately address a safety issu The licensee failed to appropriately update the NRC regarding the slipping of the expected work completion date for the above noted modification Although the commitments were tracked on both the corporate and site levels, responsible individuals were not aware of the failure to meet the commitmen Additionally, since the commitments for all CECo facilities are tracked at a common point at the corporate level, this issue and the failure to meet commitments at other sites may be an indicator of a programmatic proble For example, on three previous occasions, CECo failed to appropriately update, meet or change other commitments related to GL 89-1 At Quad Cities (Reports No. 50-254/93013(DRS) and No. 50-265/93013(DRS)), the licensee removed groups of valves from the testing program and failed to update the appropriate commitments to reflect the chang At LaSalle (Reports No. 50-373/92023(DRS)
and No. 50-374/92023(DRS)), the licensee did not appropriately update a commitment regarding the evaluation of test dat Previously at Dresden (Reports No. 50-237/92026 and No. 50-249/92026), the licensee failed to perform operator training as committed to in correspondence to the NRC regarding Supplement 3 MOV The failure to appropriately monitor and track commitments is an indicator of weak management oversight of the progra In response to the inspectors' concerns, the licensee initiated steps to identify the root cause of the problem and to take corrective action This issue will be reviewed during a future inspectio.9 3. Associated Reviews Maintenance Minimum post maintenance testing (PMT) requirements were not specified in the maintenance procedures but were designated by the lead planner based on engineering judgmen This approach was not desirable because consistent performance of appropriate PMTs could not be guarantee However, the inspectors did not identify any instances where inappropriate tests were performe The licensee recognized the weakness in the approach and planned to revise the subject documents to incorporate minimum PMT requirement The revised documents will be reviewed during a future inspectio. Walkdown The inspectors performed a general inspection of several MOV Valve the exterior condition of the MOVs was also founct to be reasonable.
plant inspection as well as a detailed stems appeared to be well lubricated and appeared to be acceptabl Housekeeping
3. Pressure Locking and Thermal Binding The actioni taken to address pressure locking and thermal binding were considered minima Replacement valves in the reactor water cleanup system were modified to preclude pressure lockin No other work was performed to modify existing MOVs to preclude pressure locking and thermal binding, although the licensee identified a substantial number of susceptible MOV In response to the inspector's concerns, the licensee agreed to consider taking additional action The failure to take steps to address this issue is considered to be a weaknes This issue will be reviewed during a future inspectio. Training The NRC inspectors reviewed the training program and training records for engineers and technicians working on MOV The training program appeared to be acceptabl. Other Initiatives The licensee has expended considerable resources sponsoring MOV research initiative For example, testing programs, sponsored by CECo, have provided the industry with valuable information on DC motors, actuator structural limits, and packing adjustments, to name a fe Additionally, the licensee was testing roller-bearing stem nuts at the time of the inspection and planned to perform testing on AC motor The licensee is considered to be an industry leader in this area. Licensee Self-Assessment The licensee's self-assessment dated January 25, 1993, contained many of the same observations disclosed by this inspectio When compared to self-assessments observed at other sites, this assessment was considered to be superior in the detail of the inspection and the depth of the finding The findings were clearly stated and action items were assigned to various members of the licensee's staff for resolutio However, due dates were not assigned for most items and the progress was thought to be slow addressing some issues (such as development of a site specific program document).
The inspectors considered the attention dedicated to the self-assessment to be a strengt.0 Exit Meeting The inspectors met with licensee representatives (denoted in Section 1) at the conclusion of the inspection on August 19, 199 The inspectors summarized the purpose and scope of the inspection and the finding The inspectors also discussed the likely informational content of the inspection report with regard to documents or processes reviewed by the inspectors during the inspectio The licensee did not identify any such documents or processes as proprietary.
APPENDIX A Date June 23, 1993 ADVANCE INFORMATION REQUEST TO SUPPORT A GL 89-10 INSPECTION On August 2 through August 20, 1993, the NRC staff will conduct an inspection of your program developed in response to Generic Letter (GL) 89-10, "Safety-Related Motor-Operated Valve Testing and Surveillance," at your Dresden Nuclear Power Plan In preparation for the inspection, the NRC staff requests that you provide the following information prior to July 19, 1993:
(1) The status of your MDV testing in response to GL 89-10, including a list of valves that have been tested and the type of test performed (static or dynamic design basis test).
Please include the following information for each tested MOV - the valve factor observed for each valve which was differential pressure (dp) tested, the test dp, the stem friction coefficients observed during static and design basis testing, the percentage of load sensitive behavior observed during the dp test, and thrust observed at torque switch trip under static and dp condition (2) A complete set of r1s1ng stem data sheets for each MOV in your program (including valve factor assumptions), or other documents that contain the equivalent informatio The information needed for an appropriate evaluation would include:
- Motor:
ac or de, nominal voltage rating, nominal torque, spee Actuator: manufacturer, type, size overall gear ratio, application factor, assumed efficiencie Valve: Manufacturer, type, pressure rating, disc area used in calculations, stem diameter, assumed valve factor, assumed stem friction coefficient, pitch and lea Design Basis Conditions: differential pressure, system pressure, worst case motor voltage, fluid temperature and flow conditions, and ambient accident temperature condition (3) Correspondence to, and from, the NRC related to your GL 89-10 progra This would include all documents that constitute the basis for your current commitment You may omit any correspondence that was submitted previously to support the Quad Cities GL 89-10 inspectio (4) A current copy of your program descriptio Please include any position papers, or other documents, that are used for justification of your position Please identify the specific recommendations, contained in the applicable position papers and other guidance documents, that are not adhered to by the sit Please provide the appropriate justification for not following any such guidanc You may omit any un-revised documents that were submitted previously to support the Quad Cities GL 89-10 inspectio *
Please mail the above information to:
USN RC Attention: George Replogle 799 Roosevelt R Glen Ellyn, IL 60137 If you have any questions please feel free to call George Replogle at (708) 790-560 Following the entrance meeting, you should feel free to make a summary presentation of the status of your motor-operated valve (MOV) program developed in response to GL 89-1 However, we request that the presentation be no longer than two hours in duratio We also request that the following information be provided to the NRC staff at the entrance meeting:
(1) the status of your actions in response to each finding, weakness, open item, or unresolved item previously identified in GL 89-10 inspection reports including:
a) Steps taken to justify generic assumptions for valve factors, stem friction coefficients under degraded and non-degraded lubricant conditions, and load sensitive behavior.
b) Steps taken to feedback test information into your GL 89-10 progra Specifically, steps taken to make programmatic adjustments for valve factors, stem friction coefficients, and load sensitive behavior based on the results of your testing progra c) Steps taken to address ambient temperature effects on MOV motors, including actions taken (and planned) in response to the recent Limitorque Part 21 Notice, "Torque at Elevated Temperatures," dated May 13, 199 d) Actions planned to justify design basis capability for MOVs which will not be subjected to dp testing, including MOVs that will not be dp tested because the maximum achievable test dp is less than 80% of the design basis d e) Justification that demonstrates that static testing (performed to comply with the periodic verification recommendation~) is sufficient to demonstrate that MOVs can perform their design basis function f) Steps taken to ensure that load sensitive behavior is accounted for when extrapolation data to design basis condition This issue was originally identified during the LaSalle GL 89-10 inspectio The CECo TIO did not appear to include margin to account for load sensitive behavior, that was observed during dp testing, when extrapolating test data to design basis condition *
g) Steps taken to ensure that the value used for a starting grid voltage corresponds to that just above, or equal to, the degraded grid under-voltage relay setpoint (including inaccuracies).
h) Justification to support the use of stall torque current, in lieu of locked rotor current, in the degraded voltage calculations, if use i) Steps taken to ensure that all the design basis analysis envelop worst case EOP scenario j) Steps taken to justify your post-maintenance testing after packing adjustment k) The status of modifications needed to improve the capabilities of MOVs subject to the recommendations contained in GL 89-10, Supplement l) Steps taken to evaluate and trend anomalies, such-as worn stem nuts, observed during maintenance activitie m) Steps taken which will enable closure of Inspection Follow-up Item (50-237/91011-01; 50-249/91010-01) - Nominal reactor pressure used in design basis analysis when the maximum reactor pressure may have been appropriate.
n) Steps taken to ensure that the data taken from the HPCI pump curves was accurat o) Steps taken to ensure that all assumptions pertaining to check valve leakage were conservativ (2) The schedule for testing and ~aintenance of MOVs during the period of the inspectio (3) A list of MOVs included in the GL 89-10 progra (4) A list of MOVs in safety-related systems which were not included in the GL 89-10 program and the reason for not including the (5) Specific justification for not performing design basis testing on MOVs included in the progra (6) An organization chart for the MOV staff and the appropriate phone number (7) P&IDs for systems which include GL 89-10 MOV (8) A schedule showing completion projections for GL 89-10 commitment (9) Procedures and results of Degraded Voltage Studies.
(10) Procedures and results of MOV sizing and switch setting calculation..
(11) Procedures and results of Design Basis Reviews.
(12) A list of MDV failures, with brief descriptions of the failures, since l/l/9 Inspectors will request additional information pertaining to specific failures during the inspectio (13) Procedures for testing, including appropriate acceptance criteri (14) Maintenance Procedures for MDV (15) Post-maintenance testing procedures for MDV (16) Specific steps taken to address various information notices pertaining to hydraulic lock and thermal binding of MDV (17) Specific steps taken to address the Limitorque Part 21 Notice,
"Torque at Elevated Temperatures," dated May 13, 199 (18) Diagnostic equipment manufacturer, devices used, assumed accuracie (19) Procedures and supporting documents related to your MDV trending program.