IR 05000237/1994007
| ML17180A666 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 03/30/1994 |
| From: | Hiland P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17180A665 | List: |
| References | |
| 50-237-94-07-EC, 50-237-94-7-EC, 50-249-94-07, 50-249-94-7, NUDOCS 9404070062 | |
| Download: ML17180A666 (26) | |
Text
u.-s. NUCLEAR REGULATORY COMMISSION REGION I II Reports N ~237/249-94007{DRP)
Dockets Nos. 50-237; 50-249 License Nos. DPR-19; DPR-25
- Licensee:
Commonwealth Edison Company Opus West III 1400 Opus Place Downers Grove, IL 60515 Facility Name:
Dresden Nuclear Power Station, Units 2 and 3 Meet~ng Conducted:
March 21, 1994 Meeting Location:
NRC Region III Office 801 Warrenville Road Lisle, I 11 i no is Type of Meeting:
Enforcement Conference Inspection Conducted:
Dresden Site Morris, Illinois Inspectors:
Reviewed By:
Approved By:
M. N. Leach A. M. Stone January 11 to February 22, 1994 e~.1,!.lht Reactor Projects Section lB
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6r1iayton, Chief Reactor Projects Branch 1 Meeting Summary
{!Xi)n Date Enforcement Conference on ~arch 21. 1994 (Report No. 50-237/249-93026(DRP)l Areas Discussed:
An apparent violation identified during the routine residen inspection was discussed, along with the corrective actions taken or planned by the 1 icensee. The enforcement options pertaining tq the apparent violation were also discussed with the licensee. The apparent violation concerned: (1) failures to implement corrective actions to preclude recurring drift and failures and of the reactor water level switches prior to 1994 and (2) failures to determine the root causes of the failures or excessive drifts, contrary to 10 CFR 50, Appendix B, Criterion XVI, "Coirective Actions.*
9404070062 9405003302137
~DR ADOCK 0 PDR
DETAILS Persons Present at Conference Commonwealth Edison Company M. Lyster, Site Vice President, Dresden.
G. Spedl, Plant Manager, Dresden R. Aker, Technical Services Superintendent H. Massif, Manager, Site Engineering and Construction (SEC}
R. Robey, Director, Site Quality Verification P. Garrett, Regulatory Assurance Engineer S. Friant, Control Systems Technician Brewer~ Supervisor, Instrument Maintenance P. Piet, Nuclear Licensing Administrator J. Shields, Regulatory Assurance Supervisor D. Spencer, Lead Electrical, SEC R. Ralph, System Engineering M. Lesniak, Regulatory Service J. Schrage, Licensing Administrator D. Paquette, Engineering Support S. L. Trubatch, Counselor, Winston & Strawn U. S. Nuclear Regulatory Commission J. B.. Martin, Regional.Administrator R. W. Defayette, Director, Enforcement and Investigation Coordination Staff _
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B. A. Berson, Regional Counsel T. 0. Martin, Deputy Director, Division of Reactor Projects H. B. Clayton,. Chief, Reactor Projects Branch 1 -
P. L. Hiland, Chief, Section lB, Division of Reactor Projects W. D. Shafer, Chief, Maintenance and Outage Section M. N. Leach, Senior Resident Inspector,_Dresden A~ M. Stone, Resident Inspector, Dresden P. R; Pelke, Enforcement Specialist C. L. Vanderniet, Reactor Inspector L. Love-Tedjoutomo, Quality Specialist, AECB, Canada D. M. Chyu, Reactor Engineer * Enforcement Conference An Enforcement Conference was held in the R~ion III office on March 21, 1994.*
This conference was conducted as a result of the preliminary findings of the inspection conducted from January 11 to February 22, 1994, in which an apparent violation of NRC regulations was identifie Inspection findings were documented in Inspection Report 50-237/249-94002(DRP), transmitted to the licensee by letter dated March 11, 1994.
. The purpose of this conference was~o: (1) discuss the apparent violation, causes, and the licensee's corrective actions; (2) determine if there were any escalating or mitigating circumstanc~s; and (3) obtain any additional information which would help determine the appropriate enforcement actio Following an introduction by the Regional Administrator, the apparent violation was presente The licensee's representatives provided additional information concerning the apparent violation. The licensee's representatives described.the events which led to the apparent violation, including root causes and corrective actions take At the conclusion of the meeting, the 1 icensee *was informed that they would be notified in the near future of the final enforcement actio Attachments:
1; NRC Presentation CECo Presentation
- ....
- U.S. NRC REGION Ill DRESDEN STATION ENFORCEMENT CONFERENCE MARCH 21, 1994 2:00 P.M. (CST)
EA 94-048 REPORT NUMBERS 50-237 /94002 AND 50-249/94002 REGION Ill OFFICE 801 WARRENVILLE ROAD LISLE~ ILLINOIS
MAJOR NRC CONCERNS INADEQUATE AND UNTIMELY CORRECTIVE ACTION PROBLEM HEPORTING ROOT CAUSE EVALUATION MANAGEMENT AGGRESSIVENESS TO RESOLVE TECHNICAL ISSUES COMMERCIAL GRADE DEDICATION PROCESS*
DRESDEN STATION ENFORCEMENT CONFERENCE Agenda INTRODUCTION AND OPENING REMARKS:
- Tom Martin, Deputy Director, Division of Reactor Projects (DRP) *
NRC ENFORCEMENT POLICY:
Bob Defayette, Di rector, Enforcement and Investigation Coordination Staff SUMMARY OF APPARENT VIOLATIONS:
Ann Marie Stone, Resident Inspector - Dresden LICENSEE PRESENTATION AND DISCUSSION:
NRC CLOSING REMARKS:
Jack Martin, Administrator, Region III
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APPARENT VIOLATIO CFR 50, Appendix B, Criterion XVI, "Corrective Action," requires, in part, that measures be established to assure that conditions
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adverse to quality are promptly identified and corrected. In the case of significant conditions adverse to quality, the measures shall assure that the cause of the conditjon is determined and corrective action taken to preclude. repetition; The "identification of the significant condition adverse to quality, the cause of the condition, and the corrective action shall be documented and reported to the
- appropriate lev~ls of managemen.
CONTRARY TO THE ABOVE Prior to 1994, the licensee did not implement corrective actions to
- preclude recurring drift and failures. of the reactor water level switches commensurate to safety significance. The root causes of the failures or excessive drifts were not determined and resulted in repeated failure The apparent violation discussed in this* enforcement conference is subject to further review and may-be subject to change prior to any resulting enforcement actio Logic:
BACKGROUND DRESDEN REACTOR WATER LEVEL SWITCHES Four Yarway level instruments, each with two mercury switches, initiate ECCS systems on low-lo_w level in a one-out-of-two twice logi * _-
Two instruments have one additional mercury switch used to isolate HPCI on high water leve The logic is two-of-tw *
. TS requires initiation at +84 (+4,-0) inches above the top of.
active fuel (-59 on instrument range). A TS change was initiated in 1989; however was not submitted until March 199 The TS change should be approved by April 199 History of Out-of-tolerances and Failures:-
In 1992 Vulnerability Assessment Team (VAT) reviewed 1989 through 1991 data and concluded twenty-five percent of the thirty out-of-tolerance events were complete failures to trip. The VAT report stated licensee should finalize the planned ~orrective action *
Since January 1991, the switches have been out-of-tolerance or
_completely faile,9 to actuate at least 50 time In 1993 alone, 29 switches as~found settings were unacceptabl *
Unit 2 level instruments were replaced like-for-like in March 199 Seventeen s~itches have not actuated properly since this replacemen *
Y~rway problem placed on Top 50 Issues list in March 199 However, no appreciable work was complete Safety significance:* '
Automatic initiation and isolation from the level switches are assumed in the following accident scenariris: Section 15.6.5. Loss of coolant accidents resulting from piping breaks inside containment: ECCS is assumed to automatically actuate on either low-low water level or high drywell pressur. *
Section 15.2.7. Loss of normal feedwater flow: HPCI initiates at low-low level setpoint. (Analysis determined that without HPCI makeup level would remain five feet above core.)
- Section 15.6.1. Inadvertent Opening of a safety/relief valve: During a concurrent loss of offsite power, HPCI automatically actuates on low-low leve *
- Section 15.5.1. Inadvertent initiation of HPCI: vessel level increases until HPCI pump turbine is tripped by hi level signal The licensee performed a detailed engineering evaluation and determined the Yarway instruments were operabl The licensee determined the failure rate for 1992 and 1993 to be 10-4 per hour whereas the failure rate ~ssumed in the IPE was Sx10:
6 per hou *
Level switch failures affected the assumed failure rate of the common actuation system (CAS)) in the IP The baseline IPE has a core damage frequen~y (CDF) of l.85xl0-5/yea The bounding case for level switch failures (failure of CAS) resulted in a CDF of 4.35xl0-5/year, an increase of 135%.
In January* 1993, the as-found settings of two switches affected the actuation logi Assuming this condition existed for 10 days, the licensee determined that this event incr~ased the CDF by 1%.
This issue was identified in the VAT, was placed on the Top 50 list but little action was taken to resolve i Examples of inadequate corrective action include the following: Prior to 1994, the licensee failed to initiate actions commensurate to safety significance to resolve Yarway instrument failure Several feasibility studies to review possible design change were initiated; however, were not completed or no actions taken to resolve long term proble Also, the proposed TS change
- was not submitted timely and was not appropriately prioritize.
following identification of problems during bench testing and installation in March 1993, the licensee did not determine root causes of the Unit 2 switch failures prior to declaring the instruments operabl.
Prior to 1994, the licensee did not determine root causes to prevent recurrence of reactor water level switche Mercury switches were disposed of without failure determination.
In 1993 the licensee failed to recognize precursors to individual instrument failures and significance of Unit 2 adverse tren Previous Inadequate Corrective Actions Violations Inspection ~eport 93034 93030 93024 93020 93003 Details of violation Corrective actions f6r a previous violation were inadequate with regards t~ control of portable carts Measures were not established to assure that deficiencies and deviations identified by contractors were corrected Corrective actions taken to re-establish CCSW train separation in October 1992 were inadequate to prevent the loss of train separation in June 199.
. Contaminated water leak not properly contained HPCI piping deformation caused by a 1970 water hammer was !lot analyzed until 1993 Additional Previous Violations Related to Engineering Support Inspection report 93034 93017 (UNR)
93009 Details of violation Violation of Order - engineering evaluation permitted isolation of HPCI room coolers System engineer response to ECCS strainer.
. bulletin poor - containment closeout support poor Two SL Ill violations for inadequate 50.59 -
unreviewed safety questions existed in CCSW system
Preliminary Conclusions:
Overall:
Poor identification and resolution of technical issue NRC identified the adverse trend in instrument performanc Engineering and Technical Support did not recognize the significance of the 1993 Unit 2 trend PIFs were h~ndled by individual system engineers and all referenced TS change and feasibility studie No root cause determinations were performe Engineering personnel were unaware of the magnitude of problems since the PIFs were not handled by the same individua +
- Site engineering performance after bringing issue to their attention was aggressiv Maintenance Recognized poor manufacturing; however, installed same instrument N6 root cause determinations since licensee di~carded switche Failed to recognize significance of Unit 2 failure trend Receipt inspection was not comprehensiv Did not identify repeatability problems nor manufacturing defect Additional concerns:
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NRC identified failure to report events. (separate Level IV violation)
/\\ttachmont 1:
UNIT 2 Emorqoncy Coro CooJ '111<1 Sy~;l.n111 Bn11c\\.or Wat.or lc!yo] Swl lchos REQUIRED PROBLEM AS FOUND.
LEVEL (F)AILURE CONTACT INITIATION LEVEL (TS/FSAR)
(D) RIFT NOTES INSTRUMENT SWITCH LOGIC DATE (INCHES)
(See #1)
(See #2)
06/11/93 (-88.6)
-59 (TS)
F B logic was operable and would wouldn't trip
- have Inf t I ated ECC /12/93 didn't trip F
B logic was* operabl.e end would have Initiated ECC '08/09/93. didn't trip F
- HPCI ISOLATION*
08/10/93 42;9
+48 D
09/03/93 2 (FSAR)
F.
10/01/93 didn't trip F
Operator action necessary to Isolate HPCI.on hi level 5-6 LPCI 07/15/93 didn't trip-59 (TS)
F.
A logic WllS operable end would have Initiated ECC C 5-6 LPCI and HPCI 06/11/93-6 (TS)
D 07/19/93-6 D 09/03/93 (-68.4)
F As found setpofnt was may not have approximately equal to the
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olovatf on of vorlablo leg 11onsfng tripped ta /01/93
. -6 D 10/29/93-5 **
Conservative setting 11/23/93-6 F 12/22/93-5 *
Conservative setting 7-8 CS, ADS and DG 10/01/93-6 (TS)
D
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10/29/93-5 *
Conservative setting
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11/23/93-6 D
Attachment 2:
UNIT 3 Emergency Core Cooling System Reactor Water Level Switches REQUIRED PROBLEM AS FOUND LEVEL (F)AILURE CONTACT INITIATION LEVEL (TS/FSAR)
(D)RIFT INSTRUMENT (SWITCH)
LOGIC DATE
{INCHES)
(See #1)
(See #2)
NOTES 263-72A 3-4
- HPCI ISOLATION 01/28/93 4 +48 (FSAR)
D 5-6 LPCI and HPCI 01/13/93-5 (TS)
D ECCS initiation delayed (both A & B logic OOT.)
7-8 CS, ADS and DG 01/13/93-5 (TS)
D 263-728 3-4
- HPCI ISOLATION 01/28/93 4 +48 (FSAR)
D 02/25/93 50,. 5 D
04/21/93 44. *D 5:.6 LPCI 01/13/93-5 :..59 (TS)
D ECCS initiation delayed (A & B logic OOT)
02/25/93-5 D 7-8 cs, Aos*and DG 06/1~/93
-.61. 3-59 (TS)
D 07 /14/93-6 F 08/16/93-6 F 01/19/94 didn't trip F
A logic was operable and would have initiated ECCS NOTES
- The technical specification limit is +84 inches above the top of active fuel which corresponds to -59 inches on the Instrument rang *
- DRIFT is defined as+/- 6.6 inches from ideal setpoint (-57 or +46 inches). A FAILURE is conside~ed any setpoint *..
outside this drift band or a failure to* actuat A:\\enfconO.wpf COMMONWEALTH EDISON ENFORCE~1ENT CONFERENCE CORRECTIVE ACTIONS TAKEN IN ASSOCIATION WITH RESOLUTION OF THE Y ARWA Y TECHNICAL ISSUE MARCH 21, 1994
AGENDA M. LYSTER INTRODUCTION H. MASSIN SUMMARY OF RESPONSES TO ~AJOR CONCERNS CHRONOLOGY.
. SAFETY SIGNIFICANCE R. AKER CORRECTIVE ACTION CONCERNS DEDICATION PROCESS CONCERNS M. LYSTER CONCLUSION A:\\enfccnf3.wpf
INTRODUCTION We are here to discuss an apparent violation of the Dresden response to Yarway level switch concerns and the resolution of technical issues related to the Yarways~
Yarways have a long history of problems.
Lack of Management awareness of increased failure rates precluded increasing the priorit *
Broad comprehensive progrc;i.m enhancements have increased Management involvement in the resolution of technical issues and will avoid recurrenc *
Program enhancements regarding root cause determination of performance failures and out-of technical specification limit issues will be illustrate *
Modifications will be implemented in the next two outages which will eliminate the need for Yarways. In the interim, actions will be taken to reduce the-Yarway failure rate to 10-5/hour by the end of June 199 A:\\enfconO. wpf
SUMMARY OF RESPONSES TO MAJOR CONCERNS
Corrective actions for recurring Yarway drifts/failures Prior to U-2 failure rate increase, the station actions leading to replacement of the Yarway instruments in U-2 were commensurate with our understanding of the safety significance
- _ack of station response to increase in failure rate at U-2 in 1993 Agree that processes were insufficient to involve right level of management attention and review.of engineering judgement - recurrence should be prevented by comprehensive program enhancement *
Failure of dedication process to identify manufacturing flaws in U-2 instrument A:\\..'"lliccmf3.wri Some flaws, which were among the characteristics listed. in the. EPRl-NCIG-based program, were found and fixed - others were beyond program purpose but were later added to accommodate statio :.
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- MAJOR CONCERNS (Continued)
Actions to ensure that previously known or currently emerging safety significant
- issues are identified, prioritized, and correcte *
- Comprehensive Programmatic enhancements to identify, prioritize, and correct problems along with evaluating the corrective actions to these problem To Identity:
To Prioritize:
To Correct:
To Evaluate: *
Integrated Reporting Program.
- Trending and Analysis of IRP data Maintenance Strategy Implementation Technical Issues Resolution Program Issues Management Program Technical Issues Resolution Program Modification Approval Process (TR8/BRC)
Modification Process Maintenance Strategy Implementation Integrated Reporting Program
Effectiveness Reviews
Trending and Analysis of IRP data Corrective Action Audits
We recognize that we have much to do..
Dresden has many long standing equipment problem *
Our record to date indicates significant progress on upgrading material condition. These actions illustrate our commitment and ability to plan and follow throug A:\\cnfconO.wpf
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CHRONOLOGY Measures reactor water lev S~nses decreasing reactor water level'
Initiates LPCl/Core Spray/ADS/HPCI Initiate~; at level of -59* which is s4* above the top of active fuel Repeated history of setpoint drift/failure
Tech Specs restrict setpoint to a limit which is difficult to
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maintain.. {other licensees have iess restrictive tech spec limits)
Failure rate perc:eived as not high enough to result in significant probability of multiple, simultaneous failu.res needed to interfere with safety function initiation. {Redundancy lost only once over the past two years)
Solutions pursued since 1986
Low priority based on safety significance
- Three recommended actions were identified
A:\\enfconO.wpf *
Tech Spec Change New Yarways Different Instruments Tech Spec applied for in 1990 as part of multi-spec amendment request (withdrawn in 1992 for non-Yarway reasons)
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- d if
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I l
i I l
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1991 -
1992 -
Early 1993-Mid 1993 -
Late 1993 -
Early 1994 -
A:\\enfconf3.wpf CHRONOLOGY (Continued)
Two studies on feasibility of alternative instruments - low priority for recommendations because low safety significance of Yarway failure rate and safety concerns associated with aiternatives did not warrant high cost VAT report recommended implementation of like-for-like replacement despite inability to find root cause of failure Tech Spec amendment request submitted separately to focus alteration on setpoint issue Vat recommendation implemented to replace like-for-like Difficulties with calibrating new switches Vendor assistance obtained Part 21 reportability assessed Top technical issues list compiled - Yarway in top 1 O of 50 issues Encouraged continuation of efforts to determine *final solution*
Failure rate of new Yarways exceeds rate of old Yarways. Not brought to Management's attention. Unit 3 replacement.rull
- scheduled based on Unit 2 result Feasibility study to use analog trip system instead of Yarway Reasonable alternative solution finally found and agreed to Solution approved and scheduled for both Units
- FAILURE RATE SOURCE IPE 1993 Bounding Case SAFETY SIGNIFICANCE OF YARWAY DRIFT/FAILURE FAILURE RATE 5 x 10-6/h /h % *
CORE DAMAGE
- FREQUENCY 1.85 x 10"5/y.85 x 10"5/y.35 X 10*5/y The bounding case is based on a failure probability of 100%.
We acknowledge that these numbers have only become available recently
This PRA evaluation validates that qur engineering judgment regarding the impact of the measured failure rate was correc *
Compensatory actions initiated pending completion of planned fixe '
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No realistic concern that failure probability could reach 100%.
Despite the low quantitative safety significance, the failure rate is inconsistent with the appropriate safety focus. *
We recognize the need for a process which alerts management to applications of engineering judgement which involves a substantial level of uncertainty and, thus, should be subjected to management revie A:\\enfconf3.wpf
CORRECTIVE ACTIONS Chronology shows continual attention to proble*m culminating in replacement of U-2 Yarway Acceptance of problem consistent with low safety significance and other, higher safety significant issue *
Too much emphasis was placed on amelioration expected from TS amendment request to a*dopt broader tolerance already authorized for other station *
VAT recognized issue and elevated management attentio *
U.-2 Yarway replacement recognized to be an effort to address the symptoms..
The decision to replace the Yarways on Unit 2 was based on the increased trend of failures over the years (1989 through 1991) compared to a significantly lower failure rate on Unit The Yarway experience is an example of long standing equipment problems that we expect to deal with by using the enhanced processe *
Acknowledge failure to appreciate possible generic impact of increased failure rate -
Resulted from lack of process for bringing technical issues to appropriate level of managemen *
Station recognized process weaknesses prior to this even *
- Compre~ensive processes and enhancements initiated and planned are expected to substantially reduce potential for recurrenc A:\\enfconO.wpf
CORRECTIVE ACTIONS (Continued)
Agree that station processes needed to be enhanced.
Enhancements are underwa First will describe enhancements in genera Then will show how they *apply to concerns about:
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root cause determination of reasons for failure of new switches and out~of-tolerances during surveillance testing -
General Description of Program Changes A:\\enfconlJ.wpf Integrated Reporting Program Lower threshold for reporting events lssu.es Management Program Modification Approval Process Efficiency results in increased approval of lower safety significance modifications Technical Issues Resolution Program Periodic self-assessment of Top Technical Issues Established more systematic process for priortization Maintenance Strategy *
Trending and Analysis
. Effectiveness Reviews Perform reviews of corrective actions to determine effectiveness of the actions
- CORRECTIVE ACTIONS (Continued)
Application to Determination of Root Causes of Switch Failures Impaired spiral wells were addressed promptly through discrepancy record Identification would now be addressed through PIF process which includes root cause analyses under specified guidelin.es..
Similarly, other deficiencies in components would be documented through PIFs and result in root cause analyses in accordance with IRP progra *
Trending and analysis of PIF data points will help to more quickly identify recurring problem *
The IQE position has been filled to provide dedicated focus to the improvement of the trending and analysis proces *
Application to Determinations of Root Causes of Out-of-Tolerance Surveillances A:\\enfconf3.wpf.
Historically, DVRs/LERs had been written and root cause had been deter.mined to be intrinsic inability of Yarway to meet narrow TS limit More recently, PIFs were written but no new root cause evaluations were performed because station believed the cause was unchange IRP trending will be improved to enhance the ability to recognize adverse trends and trigger an independent analysis of the root cause when appropriat *
DEDICATION PROCESS Dedication process based on EPRl-NCIG-07.
Dedication process discovered and. corrected some unacceptable conditions.
Other problems were det~rmined either not to affect switch performance. (cold solder joint) or appear to have arisen after receipt inspection (spiral well and switch performance).
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Dedication Was deficient iri riot requiring demonstration of repeatable actuatio This was correcte Workmanship criteria also were added to accommodate station expectation *
. Dedication process appeared to be fundamentally soun A:\\enfconf3.wpf.
Enhancements like repeatability testing are expected to be identified as process is used and refine r I '
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y '.
CONCLUSION LESSONS LEARNED
- * CORRECTIVE ACTIONS RESULTS TO DAT *--
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