ML20055C730
| ML20055C730 | |
| Person / Time | |
|---|---|
| Issue date: | 06/15/1990 |
| From: | Novak T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Liantonio V TARGET ROCK CORP. |
| References | |
| NUDOCS 9006220250 | |
| Download: ML20055C730 (2) | |
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JUN 15 1990 Mr. Vito Liantonio, Engineering Manager Target Rock Corporation 1966 E. Brcadhollow Road East Farmingdale, NY 11735
Dear Mr. Liantonio:
Subject:
Preliminary Case Study Report on Solenoid Valve Problems at U.S. Light Water Reactors A preliminary AEOD case study report, " Solenoid Valve Problems at U.S. Light Water Reactors," is enclosed.
The study analyzes and evaluates operational experience and safety implications associated with failures and degradations of solenoid-operated valves (50Vs) at U.S. LWPs.
It focuses upon the vulnerability of safety-related equipment to comon-mode f ailures or degradations of S0Vs.
The report presents information on more than 25 events in which comon-mode failures or degradations of over 600 SOVs were affected, or had the potential to affect, multiple safety systems or multiple trair,s of individual safety sy stems. Although plant safety analyses do not address such comon-mode failures or degradations of safety systems, operating experience presented in the report indicates that they have occurred and are continuing to occur.
A number of events in which safety systems have been adversely affected by degradations or failures of S0Vs are considered significant precursors. The case study notes that 50V problems permeate almost all U.S. nuclear power plants, and that they encompass many aspects of the 50Vs' design, maintenance, and operation.
The case study also notes that individual SOV manufacturer's practices regarding guidance with respect to testing and maintenance contribute towards the observed problems. The report presents six recomendations which, if implemented, should reduce reactor accident risks by reducing the likelibcod for comon-mode failure or degradation of S0Vs affecting multiple safety systems or multiple trains of individual safety systems.
In accordance with our " peer review" process, prior to the finalization and distribution of our case study reports, we are providing you and other vendors who provided input to the case study with a copy of the preliminary report for review and coment. We request that you focus your review primarily on the accuracy and completeress of the technical details (i.e., coments are being solicited on the technical accuracy of the report). The findings, conclusions, and recommendations are provided for your information in order that you may understand the significance we place on these events end, therefore, obtain a more complete picture of the total report. Changes to the findings, conclusions, and recommendations will be considered only if the underlying information concerning the details of plant design or systems operation is in error. We ask that comments be provided in writing.
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report..If you require additional-time beyond that point, please let us know..
. j to contact me or Dr. Ha1'Ornstein at (301)garding this study, please feel free If you or your. staff.have any questions re 492-4439.
j Sincerely, Original signed byt NESS I.Tovak,. Director
-Division of Safety Programs Office for Analysis and Evaluation of Operational Data
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t PRELIMINARY CASE STUDY REPORT i
SOLEN 0ID VALVE PROBLEMS AT U.S. LIGHT WATER REACTORS June 1990 Prepared by:
i Dr. Harold Ornstein Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data U.S. Nuclear Regulatory Comission L
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G' TABLE OF CONTENTS ~
Eage EXECUTIVE
SUMMARY
vii 1
INTRODUCTION....................................................
1 2
DESCRIPTION OF EQUIPMENT........................................
3 3
USE OF SOLEN 0ID-OPERATED VALVES (SOVs)..........................
B 4
SOLEN 0ID-OPERATED VALVE FAILURE MODES: APPARENT ARID. ROOT CAUSES.
10 5
OPERATING EXPERIENCE:
SIGNIFICANT EVENTS INVOLVING COMON-MODE FAILURES OR DEGRADATIONS OF SOVs................................
11 5.1 Design Application Errors..................................
11 5.1.1 Ambient Temperatures................................
11 5.1.1.1 MSIVs at Perry - Excessive Heat From Steam Leaks...............................
11 H
5.1.1.2 MSIVs at Crystal River 3 - Thermal j
Aging - Incorrect Estimation of Ambient Temperatures...............................
13 5.1.1.3 Millstone 2 - Thermal Aging - Localized
" Hot Spots" in Containment.................
13 5.1.2 Heatup from Energization.............................
14 5.1.2.1 Grand Gulf 1 MSIVs - Thermal Aging (Self-Heating From Energization)...........
14 5.1.2.2 North Anna 1 and 2, and Surry 1 and 2 -
Thermal Aging (Self Heating Due To Energization)..............................
15 I
5.1.3 Maximum Operating Pressure Differential (MOPD) -
Mul ti pl e Pl a nts.....................................
15 t.
5.1.4 Directional SOVs.....
20 t
l 5.1.4.1 Incorrect Valve Orientation at River Bend..
21 l
l
- 5. 2 Maintenance................................................
21 l
5.2.1 Maintenance Frequency...............................
22' 5.2.1.1 Dresden 3 - BWR Scram System - Primary System Leak Outside Containment............
22 5.2.1.2 Perry - Simultaneous Common-Mode Emergency Diesel Generator Failures........
24 5.2.2 -Replacement Versu's Rebuilding.......................
24 i
5.2.2.1 MSIVs at Perry - Inadequate SOV Rebuild.....
24 5.2.2.2 Brunswick 1 - Safety Relief Valves -
S0V Rebuilding Error:
Excess Loctite.......
25 l
iii
-. ~
i TABLE OF CONTENTS (Continued)-
Pag 5.2.2.3 Peach Bottom 3 - Scram System - SOV Rebuilding Error:
Excess Loctite...........
27 5.2.3 Contamination........................................
28 5.2.3.1 Brunswick 2 MSIVs - Excessive Heat and
~
Poor Air Quality (Hydrocarbons and Water)...
28 5.2.3.2 North Anna 1 and 2 - Multiple Systems Oil and Water Intrusion.........................
28 1
5.2.3.3 Susquehanna 1 and 2 - Scram System:
Oil l
and Water Contamination.....................
'31-l 5.2.4 Lubrication'..........................................
32 5.2.4.1 Multiple Plants - Manufacturing Error:
l Residue-Producing Lubricant.................
32 5.2.4.2 Catabwa:
PoorQualit with Vaseline.......y Air and Lubrication 34 5.2.4.3 Common-Mode Failure of 16 MSIVs at a Two Unit Station (BWRs):
Incorrect Lubrication.
35 j
5.2.4.4 Grand Gulf 1, LaSalle 1, and River Bend MSIVs - Sticking SOVs - Foreign Unidentified
~;
Sticky Substance (FUSS) - Lubricant Suspected...................................
36 i
l 5.3 Surveillance Testing........................................
40 5.3.1 Control Rod Timing Tests - Failed Scram Pilot SOVs - Perry.........................................
40 5.4 Use of Non-Qualified SOVs...................................
40 y
l' 5.4.1 Colt /Fairbanks - Morse EDGs:
Repetitive Air l
Start Valve Failures.................~................
40 6
ANALYSIS AND EVALUATION OF OPERATIONAL EXPERIENCE................
42 l
6.1 Common-Mode Failures........................................
42 6.2 'SOV Failure Rates...........................................
43 6.3 Maintenance Problems........................................
44 h
-6.3.1 Maintenance Problems - SOV Manufacturer's i
Contributions........................................
44 6.3.2 Maintenance Problems - Contribution of the i
Unrecognized S0Vs....................................
46 6.3.2.1 Unrecognized SOVs in Emergency Diesel Generators..................................
46 6.3.2.2 Unrecognized SOVs in Auxiliary and Main Feedwater Systems......................
47 iv
y TABLE OF CONTENTS (Continued)
J Pa21-i 6.3.2.3 Unrecognized SOVs in BWR High Pressure CoolantInjectionSystems...................
47 6.3.2.4 - Unrecognized SOVs in Instrument Air Dryers..
47' 6.3.3 Maintenance Problems - Contributions of Utility Programs and Practices...............................
47 6.3.4 Rebuilding vs. Replacement...........................
48 7
FINDINGS.........................................................
50
'7.1 Design Application Errors...................................
50 7.1.1 Ambient Temperatures.................................
50 7.1.2 Heatup-from Energization.............................
50 7.1.3 Maximum Operating Pressure Differential..............
50 7.1.4 Unrecognized SOVs Used as Piece-Parts................
51 7.1.5 Directional SOVs.....................................
51 7.2 Maintenance.................................................
51 7.2.1 Maintenance Frequency................................
51 7.2.2 Replacement Versus Rebuilding........................
52 7.2.3 Contamination........................................
52 7.2.4 Lubrication..........................................
53 7.3 Surveillance Testing........................................
53
- 7. 4 Verification of the Use of Qualified SOVs...................
53 7.5 Redundancy and Diversity....................................
53 7.6 Feedback of Operating Experience............................
54 f
8 CONCLUSIONS......................................................
55
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1 8.1 Safety Significance.........................................
55 8.2.Need For Action.............................................
56 9
RECOMMENDATIONS..................................................
'57 1'
l 9.1 De s i g n. Ve ri fi ca ti on........................................
57 9.1.1 Ambient Temperatures.................................
57 9.1.2 Heatup From Energization.............................
57 9.1.3 Maximum Operating Pressure Differential..............
57 9.1.4 Unrecognized SOVs Used as Piece-Parts................
57 9.1.5 Directional S0Vs.....................................
57 9.2 Maintenance.................................................
57 9.2.1 Frequency............................................
57 9.2.2 Replacement Versus Rebuilding........................
58 v
TABLE OF CONTENTS (Continued)
Ph9e 9.2.3 Contamination........................................
58 9.2.4 Lubrication..........................................
58 9.3 Surveillance Testing........................................
58 9.4 Verification of the Use of Qualified SOVs...................
58 9.5 Redundancy and Diversity....................................
59
- 9. 6 Feedback of Operating Experience............................
59 10 REFERENCES.......................................................
60 APPENDIX A SOV Failures Reported in LERS:
1984-1989................
A-1 B
Disposition of ASCO Dua' s.iil 8323 SOVs Used for.........
B-1 MSIV Control C-Generic Communications ca SOVs...........................
C-1 vi
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EXECUTIVE StM4ARY The study analyzes U.S. light water reactor (LWR) experience with solenoid-U operated valves (SOVs).
It focuses upon the vulnerability of safety-related equipment to common-mode failures or degradations of SOVs.
The report presents information on over twenty events in which common-mode failures or degradations of over 600 SOVs affected, or had the potential to affect, multiple safety systems l
or multiple trains of individual safety systems.
Although plant safety analyses do not address such common-mode f ailures or degradations of safety systems, operating experience presented in the report indicates that they have occurred, and are continuing to occur.
The events in which comon-mode failures of SOVs have affected multiple
/
trains of safety systems or multiple safety systems are important precursors.
They indicate that actions are necessary to assure that important plant systems function as designed in accordance with plant safety analyses, and that plants are not subject to unanalyzed failure modes with the potential for serious consequences.
The report analyzes the operating experience and it outlines the root caus.es of comon-mode failures and degradations that have been observed, and provides recommendations to significantly reduce the occurrence of common-mode 50V failures.
Analysis of operating data indicates that the underlying or root causes of many 50V failures are the users' lack of knowledge or understanding of SOVs' requirements or capabilities, such as:
SOVs' intolerance to process fluid contamination; the necessity for preventive maintenance or changeout; and the propensity for rapid aging and deterioration when subjected to elevated tempera-
- Compounding the problem is the fact that some 50V manufacturers do not tures.
provide the users with adequate guidance regarding proper SOV maintenance and operation.
Further complicating the situation is the fact that many S0Vs are
" unrecognized" i.e., they are provided as piece parts of larger components so that the end users have a restricted knowledge of the 50Vs' operation and main-tenance requirements, or their useful design life.
l ort addresses widespread deficiencies which were found in the areas The rep / application, maintenance, surveillance testing, and feedback of design
- of:
failure data.
It is recomended that for safety-related applications, licensees:
(1)-
verify the compatibility of SOV design and plant operating conditions; (2) ver-ify the adequacy of plant maintenance programs; (3) ensure that SOVs are not subjected to fluid contamination (e.g., instrument air); (4) review SOV surveil-
-lance testing practices; and (5) verify that all SOVs which are used in safety-related applications have been manufactured, procured, installed and maintained commensurate with their safety fun'ction to assure operation consistent with plant safety analyses.
Specific technical information supporting these broad recomendations is contained throughout the report.
Detailed recomendations are provided in Chapter 9.
PRELIMINARY CASE STUDY vii
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l In addition,--it is recommended that' an industry group such as.INP0 take
't
- action to improve.the mechanism for feeding back SOV. failure data to the manu-i facturers for early. detection and resolution of potential generic problems, i
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1 PRELIMINARY CASE STUDY viii
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1-INTRODUCTION All U.S. light water reactors (LWRs) rely upon solenoid-operated valves (SOVs) to perform safety-related and non-safety-related functions.
SOVs are used to operate with hydraulic and pneumatic fluids under a wide variety of con-ditions. They are used to control process fluid either directly, or indirectly as pilot controllers.
It has been estima;.ed that the population of SOVs in safety systems at U.S. LWRs is between 1,000 and 3,000 per plant (Ref. 1).
Boiling water reactors (BWRs) usually have more SOVs than pressurized water reactors (PWRs), because of the extensive use of SOVs in BWR scram systems.
Many SOVs used in nuclear power plants are dedicated / qualified valves, which have undergone vigorous qualification testing to standards such as the Institute of Electrical and Electronics Engineers (IEEE) Standards 323, 344 and 382, and are manufactured in accordance with the Nuclear Regulatory Commission (NRC) requirements of Title 10 of the Code of Federal Regulations, Part 50 (10 CFR Part 50) Appendix B, and 10 CFR Part 21.
However, we have also found manycasesinwhlchplantsusecommercial,nonqualifiedSOVstoperformsafety-related functions.
This-study was initiated after several licensees experienced repetitive failures of SOVs at their plants and after the simultaneous failure of four SOVs at the Brunswick 2 plant on January 2,1988 (Ref. 2).
The Brunswick event resulted in a loss of containment integrity when two sets of redundant SOVs failed to close upon demand.
The NRC Office for Analysis and Evaluation of Operational Data (AEOD) has reviewed and participated in follow up work that the licensees, the NRC regional inspectors, and the valve manufacturers have performed following the S0V failures at Brunswick and several other plants.
A number of other significant operational events have occurred involving malfunctioning SOVs.
Previous studies of SOV failures (Refs. 1, 3, 4, 5) dis-cussed SOV failure rates and provided a characterization of the degradations or failures.
This study addresses root causes and the generic nature of many of the observed failures.
Some of the significant events discussed in this report are:
Emergency diesel generator (EDG) failures at Perry and Catawba HSIV failures at Perry, Brunswick, Grand Gulf, LaSalle and River Bend AFW System degradation at Calvert Cliffs and North Anna Losses of containment in'tegrity at Kewaunee, North Anna, and Brunswick BWR scram system component failures at Susquehanna, Brunswick and Dresden Safety Injection System degradation at Calvert Cliffs PRELIMINARY CASE STUDY 1
i Chapters five and six of this study provide comprehensive reviews and evaluations of. operational experience and potential safety implications asso-ciated with SOV problems at U.S. LWRs.
This study provides several recommenda-tions to address the. major deficiencies which were noted during the review of the operating experience.
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PRELIMINARY CASE STUDY 2
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DESCRIPTION OF EQUIPMENT There are many manufacturers and varieties of SOVs used at nuclear power plants.
SOV operation is based upon changing the electrical status of the i
valve's electro-magnetic coil, which in turn causes a shift of the position of an internal core.
The core acts to open or block the passageways inside the valve, changing the flow path within the valve.
A simplified version of a two-t L
way SOV is illustrated in Figure 1.
Figures 2 through 4 illustrate other more complex SOVs which are made by three different manufacturers.
SOVs are available for use over a wide range of temperature and pressure conditions for liquid and gas service.
They are available with the following formats:
normally open or normally' closed fail open, fail closed, fail as is normally energized or normally de-energized ac or de power, or both ac and de power two-way valves, three way valves, four-way valves direct lift, pilot assist, balanced disc, gate, modulating control.
There is a wide range of sophistication and quality of SOVs.
For example, mass produced SOVs are available for horne consumption for a few dollars each, whereas a limited production of high quality SOVs are available at a much higher price.
SOVs that are qualified for Class 1E nuclear service (meeting IEEE Stan-dards 323, 344, 382, American National Standards Institute (ANSI) N45.2 and 10 CFR Part 50, Appendix B, and 10 CFR Part 21 requirements and having American Society of Mechanical Engineers (ASME)Section III "N" or "NPT" stamps) may cost several thousands of dollars.
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PRELIMINARY CASE STUDY 3
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4 Assem ly Solenoid Coil Terminal Solenoid Board Assembly Bonnet Assembly Fixed Core Return Spring Moveable Core Main Disc Pilot Disc j
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PRELIMINARY CASE STUDY 7
3 USE OF SOLEN 0ID-OPERATED VALVES In many applications SOVs are used as alternates to motor-operated valves (MOVs).
SOVs are frequently used as pilot operators to control air-operated valves (A0Vs).
The advantages of using SOVs instead of MOVs are that they generally have fewer moving parts, are compact and may be easier to mount.
They also have low power requirements and have fast response times.
Some 50V manufacturers' literature claim that SOVs have long qualified lives, have low initial and installed costs, and require low maintenance.
The use of ADVs, MOVs and SOVs is a matter of preference of applicction that is determined by the utility, nuclear steam system supplier, and-architect engineer; their specific utilization is not a licensing requirement.
Table 1 lists many of the systems that use SOVs at U.S. LWRs.
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PRELIMINARY CASE STUDY 8
o Table 1 Systems Which Use SOVs at U.S. LWRs 1.
PWR Rod Control 3.
Reactor Coolant (RCP seal) 4.
SafetyInjection 5.
Primary Containment Isolation 7.
High Pressure Coolant Injection / Reactor Core Isolation Cooling 8.
HighPressureInjection 9.
Automatic Depressurization 10.
Emergency Diesel Generator 11.
Instrument Air 12.
Chemical Volume Control / Charging and Letdown /Boration 13.
Pressurizer Control 14.
Steam Generator Relief (PDRVs, ADVs) 15.
Low-Temperature Overpressurization Protection
- 16. Decay Heat Removal / Residual-Heat Removal
- 17. Component Cooling Water 18.
Service Water 19.
Reactor Head Vent 20.
Steam Dump 21.
Reactor Cavity / Spent Fuel / Fuel Handling
- 22. Torus and Dryweil/ Vent and Vacuum 23.
Emergency DC Power
- 24. Main Steam (Main Steam Isolation Valves / Auxiliary Boiler) 25.
Reactor Building / Auxiliary Building (Ventilation and Isolation)
- 26. Main Feedwater 27.
Condensate
- 28. Moisture Separation / Reheat
- 29. Containment Atmosphere / Containment Spray 30.
Standby Gas Treatment 31.
Floor / Sump Drain 32.
Sampling (normal and post-accident) 33.
Fire Suppression 34.
Turbine / Generator 35.
Reactor Building Purge 36.
Containment Air Lock 37.
Leak Detection 38.
Radwaste-PRELIMINARY CASE STUDY 9
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SOLENOID-OPERATED VALVE FAILURE MODES:
APPARENT AND ROOT CAUSES Previous studies (Refs. 1, 3, 4, 5) have noted that details of the failure mechanisms, the apparent causes, or the root causes of SOV failures were not provided in approximately half of the licensee event reports (LERs) and nuclear plant reliability data system (NPRDS) failure records for years 1978 through 1984.
Appendix A of this report provides a listing of approximately 200 LERs describing SOV failures which occurred at U.S. LWRs between 1984 and 1989.
The apparent and root causes of most (approximately 75 percent) of the SOV failures reported in LERs between 1984 and 1989 are given below:
a.
Coil failure or burnout that was attributed to design or manufacturing deficiencies (early failure /end of life) or an error in application (type of current, voltage level, environmental conditions).
[11%]
b.
Valve body failure or leakage that was attributed to design or manufactur-ing deficiencies, such as excessive tolerances on internal parts; excessive wear / degradation of gaskets, 0-rings, seals, or springs; or foreign particulates preventing proper sealing.
[13%)
c.
Passageway blockage / internal binding that was attributed to contaminants such as dirt, corrosion products, desiccant, water or moisture, incorrect lubricants, excessive lubrication, or hydrocarbons.
[9%)
d.
Electrical malfunctions that were attributed to faulty internal wiring, reed switch shorts or external wiring with inadequate connections, splices, or grounds.
[12%)
e.
Design errors or misapplications that were attributed to incorrect valve configuration (normally open vs. normally closed; normally enerQized vs.
normally de-energized); incorrect designation of " fail-safe" condition; incorrect electrical source (ac vs. de, voltage level); incorrect desig-nation of environmental conditions (temperature, moisture, radiation);
incorrect designation of maximum operating pressure differential; incorrect material selection (incompatibility between elastomeric parts and process fluid contaminants); incorrect valve orientation (horizontal vs. vertical).
[13%]
f.
Installation errors that were attributed to incorrect physical orientation (backwards, upside-down), electrical source (ac vs. de, voltage level),
or inadequate electrical connections (e.g., loose connections, incorrect grounds).
[7%)
g.
Maintenance errors that were attributed to incorrect determination of useful life or time between overhauls; inadequate preventive mainte-nance or incorrect preventive' maintenance.
[7%]
h.
Sticking that was the result of unidentified foreign substances coating valve internals, excessive use of lubricant, or foreign particulates.
[5%]
. PRELIMINARY CASE STUDY 10
4 5
OPERATING EXPERIENCE: SIGNIFICANT EVENTS INVOLVING COMMON-MODE FAILURES OR DEGRADATION OF SOVS The events described below were chosen as a representative set.
They should not be construed as being a complete set of common-mode failures and degradations of SOVs.
Additional events are tabulated in Appendix A.
Many other SOV failures fall below NRC reporting requirements, and as a result are not captured in the LER data base.
Many individual SOV failures not reported in the LER data base are reported in the Nuclear Plant Reliability Data System (NPRDS) data base.
Reference 1 noted that for 1978-1984 data, all SOV failures reported in LERs were also reported in NPRDS.
5.1 Desian Application Errors Representative operating experience illustrating design application errors associated with high ambient temperature, internal heatup from energization, incorrect maximum operating pressure differential and incorrect valve orienta-tion are described below.
Based on this experience, findings and recommenda-tions relevant to design application errors are provided in Sections 7.1 and 9.1 respectively, 5.1.1 Ambient Temperatures l
5.1.1.1 MSIVs at Perry - Excessive Heat From Steam Leaks On October 29, 1987, while performing stroke time testing, three of the plant's eight MSIVs failed to close within the plant Technical Specifications' allowable time of five seconds.
Two of the MSIVs were in the same main steam-line.
During subsequent testing, each of the three valves closed within the Technical Specifications value.
Since the valves all stroked satisfactorily subsequent to their initial Ga failures, the licensee believed that the failures were due to the presence of impurities.in the air pack SOVs controlling the MSIVs, and that the impurities were apparently discharged during subsequent MSIV operation.
As a result, the three MSIVs that had failed were declared operable.
-These MSIV air packs consist of a single-coil 4-way SOV (ASCO NP8320),
a dual-coil 3-way SOV (ASCO NP8323) and three poppet type air pilot-operated valves (2, 3, and 4-way CA Norgren Co.).
A photograph of one of the Perry plant's MSIV air packs appears in Figure 5.
In response to NRC concerns, the licensee performed additional MSIV stroke testing.
As a result on November 3, 1987, the inboard and outboard MSIVs in the "D" line again failed to close within the required 5 seconds (outboard MSIV closed in 2 minutes and 49 seconds;and the inboard MSIV closed in 18 seconds).
Additional MSIV stroke tests were performed, and both MSIV's again closed within the Technical Specification allowable times.
PRELIMINARY CASE STUDY 11
ASCO Dual-Coil NP8323 SOV cy r. -::,_
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Because of continued NRC concerns about MSIV reliability, the licensee shut down the plant and established a plan to find the *oot cause of the MSIV fail-ures (Refs. 6, 7 8).
Intense-investigative efforts were conducted by the util-ity to determine the root cause of the MSIV failures. The failures of the MSIVs on both October 29 and November 3,1987, were attributed to the failure of the ASCO dual-coil Model NP8323 SOVs to shift position upon de-energization.
The SOVs failed to shift position because of degradation of their ethylene propylene dimer (EPDM) seats and discs.
The degradation was caused by high temperatures that had existed in the vicinity of the SOVs as a result of several steam leaks.
Originally, hydrocarbon irtrusion was suspected as having contributed to the degradation of the EPDM seats and discs.
It was not until microscopic and spec-tral analyses were performed at an independent laboratory a month after the event that the possibility of impurities from hydrocarbon intrusion was elimi-nated as a root cause of these failures (Ref. 9).
However, as part of its cor-rective action to prevent future failures, the licensee took steps to improve the maintenance of the. instrument air system.
In addition, the licensee under-took an aggressive program to review the effects of all known steam leaks that could affect other safety-related equipment.
5.1.1.2 MSIVs at Crystal River 3 - Thermal Aging - Incorrect Estimation of Ambient Temperatures In April 1989, NRC inspectors reviewed the environmental qualification of electrical equipment at the Crystal River 3 plant.
Their review found that errors had been made in the licensee's determination of the service life of 16 normally de energized SOVs that are used to pilot the plant's MSIVs (Ref. 10).
The licensee's determination of S0V service life was made assuming an ambient temperature equal to the weighted average of the temperature of the areas where the S0Vs were located.
The licensee's calculations did not consider the localized elevated temperatures that the SOVs were subjected to as a result of hot process piping.
Recalculation of the service life of the SOVs using representative ambient temperatures reduced the estimated service life of the SOVs from 40 years to 8 years.
As a result, the licensee is replacing those SOVs sooner than previously anticipated, 5.1.1.3 Millstone 2 - Thermal Aging - Localized " Hot Spots" in Containment In November 1988, an NRC inspection report (Ref. 11) noted that Millstone 2's environmental qualification program recognized a significant shortening of the qualified lifetime of eight Valcor SOVs that are used for pressurizer and reactor vessel head vents.
Originally the SOVs were calculated to have quali-fied lives of 40 years based upon an ambient temperature of 120*F.
Although the plant's Technical Specifications require that the " primary containment average air temperature" does not exceed 120 F, the licensee found localized " hot spots" of 157'F in the vicinity of the eight S0Vs.
The licensee determined that the increase in ambient temperatures from 120'F to 157'F shortened the lifetime of the'SOVs from 40 years to 12 years.
The problem of equipment degradation due to localized hot spots is not unique to Millstone 2.
Reference 12 lists several other plants that have experienced localized thermal " hot spots" inside contain-ment.
In addition, NRC Information Notice 89-30 (Ref.13) noted that similar heating events have been reported s'ince 1982.
The information notice alerted licensees to the potential for exceeding equipment's qualification specifications when the bulk temperatures are measured by a limited number of sensors that indicate acceptably low average temperatures.
PRELIMINARY CASE STUDY 13
O 5.1.2 Heatup from Energization 5.1.2.1 Grand Gulf 1 MSIVs - Thermal Aging (Self-Heating From Energization)
On August 14, 1989, following a reactor trip,'one MSIV (inboard "B" line) failed to close upon demand (Refs. 14,15,16).
The MSIV did close about 30 minutes later.
The failure of the MSIV to close was attributed to the failure of an ASCO dual-coil NP8323 SOV, a piece part of the MSIV air pack.
The licen-see's investigation found a piece of EPDM from the SOV's disc on the 50V's out-let SOV' port screen.
The licensee concluded that the piece had been lodged in the s internals, thereby keeping the S0V from venting control air and hence keeping the MSIV from closing.
It is believed that after the EPDM piece became dislodged from the internals, the MSIV closed.
Subsequent inspections by the licensee of all eight ASCO dual-coil NP8323 SOVs piloting the MSIVs disclosed that all eight had degraded seats.
Initial visual inspection did not reveal the degradations which became apparent under microscopic examination.
TheEPDMseatsofallelghtSOVshadcracks.
- However, on six of them, the raised portior of the seat, formed by the annular impression made by the seat of the exhaust fort, was missing.
It appeared that six of the eight S0Vs had experienced similar sloughing of material from the seat.
The August 14, 1989 failure is believed to have been caused by a piece of the EPDM disc material which had been extruded into the 50V's exhaust port vent hole.
The extruded material had separated from the disc as a result of the adhesive and frictional force: when the normally energized 50V was de-energized.
The frictional and adhesive forces eventually led to the tearing off of the extruded parts of the EPDM discs.
-The extrusion of EPDM discs is discussed in GE Service Information Letter (SIL) 481 (Ref. 17).
SIL 481-notes that the intrusion of the disc into its ex-haust port may account for previous events involving the sticking of similar EPDM dual-coil'SOVs, but tearing of the discs had not been observed previously.
It is believed that the tearing and overall degradation of the dual-coil SOVs' EPDM discs at Grand Gulf was symptomatic of thermal degradation resulting from the excessive time the EPDM materials were exposed to high service temperatures.
The EPDM discs had been operating at elevated temperatures due to the energiza-tion of the dual coils.
The local temperatures inaide the SOVs near the EPDM discs were approximately 325'F inside the inboard SOVs in a 135'F drywell and 305'F inside the outboard SOV in a 125*F steam tunnel.
The SOVs had been in service for approximately 4.5 years. -However, the qualified lives of the degraded EPDM discs are estimated to have been 2.2 years for the inboards and 3.2 years for the outboards based upon environmental temperatures of 135 F'for the inboard SOVs and 125'F for the outboard SOVs.*
The NRC issued an information notice on this event, noting the life shortening effects of self-heating from coil energization (Ref. 18).
Subsequently, ASCO issued a service bulletin providing licensees with heat up data for all their nuclear qualified S0Vs (NP series).
(Ref. 19).
- 0ther EPDM discs in the same S0V which were exposed to slightly higher temperatures were estimated to have had qualified lives of 1.58 and 2.28 years, respectively.
PRELIMINARY CASE STUDY 14
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5.1.2.2 North Anna 1 and 2, and Surry 1 and 2 - Thermal Aging (Self Heating Due to Energ12ation)
In December 1986, Virginia Electric & Power Co. (Vepco) requested ASCO to provide information regarding the effects of "self heating" in continuously energized SOVs.
ASCO's response indicated that a significant increase in temp-erature would occur and that the temperature increase could result in a signi-p ficant reduction in the qualified life of the SOVs.
The licensee recognized that previous estimates of SOV service life did not account for the effects of self heating (Refs. 20, 21).
The licensee evaluated the affected SOVs and determined that, contrary to previous analyses, 125 SOVs would require replace-ment at North Anna 1 and 2 between the 1987 and 1989 refueling outages (Ref. 22).
The SOVs affected piloted air-operated valves, many of which served containment-isolation functions.
The systems affected were:
SafetyInjection, Reactor Coolant, Main Steam, Component Cooling Water, Containment Vacuum, Radiation l
Monitoring, Sampling Systems, Instrument Air, Post Accident Hydrogen Removal, Heating and Ventilation, Steam Generator Blowdown, Gaseous Vent and Aerated Drains.
The licensee recognized that Surry 1 and 2 were similarly affected, and Vepco engineering informed personnel at the Surry station of this problem.
Similarly, Surry 1 and 2 required early replacement of 58 ASCO S0Vs because of self heating.*
i It is interesting to note that the licensee for North Anna station stated in a Deviation Report (Ref. 21) that these findings were non-reportable because:
"NRC and utilities are aware of this issue to some extent." In Reference 20, the licensee noted that it had learned of this problem initiall with " industry representatives" at Equipment Qualification (EQ)y from discussions seminars in late 1986.
5.1.3 Maximum Operating Pressure Differential (M0PD) - Multiple Plants Many plants have experienced conditions in which SOVs failed or could have failed to perform safety-related functions because of excessive operating pres-sure differentials.
Figure 6 is a schematic diagram of an 50V, illustrating how an operating pressure differential in excess of its maximum operating pres-sure differential (MOPD) can cause an SOV to malfunction. When the SOV is in l
L the de-energized position, pressurized fluid enters the valve at port 2 and is blocked by the core assembly.
If the pressure differential between ports 2 and 3 exceeds the M0PD, the overpressure could lift-the core assembly, resulting in leakage of fluid from port 2 to port 1 and port 3.
1 In the energized position the core assembly is raised to block the exhaust port (port 3).
However, the excess pressure would act to retard or prevent the core subassembly from dropping down (shifting) upon de energization.
As a re-sult, de-energizing the valve would not assure the valve achieved its correct
-de-energized position (block off port 2).
L l
- Telecopy communication between W. Murray, Vepco, and H. L. Ornstein, USNRC, December 19, 1989.
PRELIMINARY CASE STUDY 15
Port 3 Exhaust Solenoid Base Sub Assembly Coil Core Assembly
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For many SOVs, the M0PD rating does not appear on the nameplate or in the installation and maintenance instructions.
Vendor catalogs need to be consulted to determine those 50Vs' MOPD ratings.
In May 1988, the NRC issued Information Notice 88-24 " Failures of Air-Operated Valves Affecting Safety-Related Systems" (Ref. 23).
It informed licensees of two SOV failures which were experienced at Kewaunee (Raf. 24) and of the potential for additional failures at Kewaunee and Calvert Cliffs 1 and 2
-(Refs. 25-27).
Subsequently, several licensees informed the NRC of similar dis-coveries in their plants, where the potential for overpressurizing SOVs exists, which could prevent the SOVs from performing their safety-related functions.
At some plants, the task of verifying the potential for overpressurizing SOVs has been complicated by the fact that documentation is not readily available.
For example, Millstone 1 and 2 (Ref. 28), Crystal River 3 (Ref. 29), have re-ported that documentation to identify SOVs in containment is not readily available, and that containment walkdowns are necessary for their identification.
It is not clear that Information Notice 88-24 has been effective in eliminating the potential for 50V overpressurization.
Our concern is predicated upon Ref. 29 and a followup discussion in which the Crystal River 3 licensee stated that its review of the potential for 50V overpressurization assumed the proper operation of in-line pressure regulators, it did not address the conse-quences of pressure regulator failures.
One of the events described in Infor-mation Notice 88-24 involved the discovery at Calvert Cliffs that several safety
-systems were-vulnerable to single failures of pressure regulators in the air supply system.
The earliest SOV overpressurization failures that we found occurred in 1980 at the Pilgrim plant.
On October 7, 1980 and again on October 31, 1980, a safety relief valve (SRV) spuriously opened while the reactor was at power.
On each occasion, the SRV did not reclose until the reactor was shutdown and the reac-tor coolant system was depressurized.
The spurious valve openings were caused by excessive pneumatic (nitrogen) supply pressure to the SOV controlling the SRV.
The high nitrogen pressure exceeded the 50V's MOPD, causing the S0V to shift position which caused the SRV to spuriously open.
The NRC issued an information notice and a bulletin on these events (Refs.
30,31).
Information Notice 80-40 (Ref. 30) indicated that two-stage SRVs with Target Rock S0Vs are susceptible to such MOPD malfunctions, whereas older three-l stage SRVs having ASCO or AVC SOVs are not.
Bulletin 80-25 (Ref. 31) required l
licensees to review and upgrade their SRV pneumatic supply systems and/or SOVs to assure that the SOVs operate within their maximum operating pressure.
The l'
bulletin required licensees to install protective devices (such as relief valves) to protect the SOVs against excessive supply pressures.
The issue of overpressurization failures of SOVs in other systems was not addressed in the information notice or the bulletin.
The discovery of the potential for overpressurizing multiple SOVs at the Vogtle plant was reported in Reference 32.
Reference 32 described a situation 1
- Telephone discussion between L. Kluit, Florida Power Corporation, and H. L.
Ornstein, USNRC, October 10, 1989.
PRELIMINARY CASE STUDY 17
4
-in which SOVs controlling the operation of all eight MSIVs could fail because of overpressurization due to overheating.
The MSIV manufacturer (Rockwell) had noted that a small steam-line break in the vicinity of the plant's MSIVs could cause an increase in the hydraulic fluid pressure in excess of the SOVs' maximum operating pressure differential.
These SOVs were manufactured by the Keane Company.
As a result of SOV overpressurization, both MSIVs on one or more steam-lines could allow uncontrolled blowdown of more than one steam generator following a main steam or feedwater line break.
Essentially, if the MSIVs' hydraulic actuator fluid heated up 12'F, a condition not bounded by the plant's safety analyses could result.
The licensee's corrective action was to replace the SOVs with others having higher M0PD ratings.
In November 1987, the Kewaunee plant actually experienced two SOY failures caused by overpressurization (Ref. 24).
During review of the two SOV failures, the licensee found that 58 additional SOVs could fail to perform their' safety-related functions as a result of overpressurization.
In April 1988, the licensee of Calvert Cliffs 1 and 2 found that 40 SOVs could fail to perform their safety-related function as a result of overpressuri-l zation (Ref. 25)
In the case of TMI-1, (Ref. 32) the SOVs were connected to line pressures in excess of the maximum dictated by the 50Vs' MOPD, In the case of Kewaunee and Calvert Cliffs 1 and 2, it was found that failure of a non qualified pressure t
regulator under accident conditions could result in the SOVs being subjected to supply pressures in excess of the maximum allowed by the 50Vs' M0PD.
Eight reported events in which SOVs failed, or had the potential to fail, to perform their safety-related functions as a result of excessive operating pressure differentials are briefly described below.
(1)
Three Mile Island-1; October 17, 1980; (Ref 32) l The following 11 containment isolation valves could have been prevented from achieving their safeguard positions:
2 makeup to core flood tanks 2 core flood tank sampling 1 reactor building vent 6 fan motor coolers for the reactor building cooling units.
(2) Vogtle-1; January 22, 1987; (Ref. 33) l l
8 main steam isolation valves could have failed to perform their safety i
function.
(3) Kewaunee; November 28, 1987; (Ref. 24) 2 containment isolation valves failed to close 1 pressurizer relief tank makeup 1 RCDT pump discharge (its redundant S0V had the potential for similar failure) 58 other SOVs in safety-related applications were also found to be subject to overpressure failure.
PRELIMINARY CASE STUDY 18
(4) Calvert Cliffs 1,.2; April 14, 1988; (Refs. 25, 26, 27)
The following 40 SOVs, equally distributed between Units 1 and 2, had the potential to fail:
8 auxiliary feedwater system 8 steam generator blowdown isolation system 6 reactor coolant pump bleedoff isolation 18 safety injection system (fill and vent)
(5) Pilgrim 1; July 19,1988; (Refs. 34, 35, 36)
The following six SOVs had the potential to fail due to overpressure:
4 control room high efficiency air filtration system damper controls (2 in each train) l' standby gas treatment system damper control 1 primary containment system RCS sample line isolation valve (6) Millstone 2; October 8 1988; (Ref. 37)
One containment isolation valve failed as a result of an air pressure regulator that failed high.
(' 7) Millstone 1, 2 and 3; November 8, 1988; (Ref. 28)
Unit 1:
The status of 16 SOVs in safety-related functions was' unknown because of a lack of design information, i
Unit 2:
A total of 24 " harsh environment safety valves and their installed EEQ (sic) solenoid valves" could have failed as a result of overpressure (one of the-24 had failed on October 8, 1988).
The licensee also noted that the status of an unspecified number of safety-related SOVs was undetermined because the " data base is incomplete as to solenoid make and model number."
l Unit 3:
Approximately 20 SOVs installed in " safety valve configurations" could have failed because of overpressurization.
The specific applications of these SOVs were not listed.
However, the li-censee indicated that there are many additional inaccessible S0Vs that'may also be susceptible to overpressure failure.
The licensee indicated that determination of such vulnerability would be made subsequent to future walkdowns when SOV nameplate data could be obtained.
(8) Crystal River 3; November 8,1988, January 5,1989 and January 11, 1989:
(Refs. 29, 38, 39, 40)
Five containment isolation valves had the potential to fail due to overpressure:
2 once through steam generator blowdown lines 2 once through steam generator sample lines 1 reactor coolant pump seal controlled bleed off line PRELIMINARY CASE STUDY 19
5.1.4 Directional SOVs We are aware of seven plants that have observed spurious operation of safety-related Target Rock angle-type SOVs due to improper valve orientation.
As shown in Figure 3. upstream fluid pressure at the angle-type 50V's inlet port assists valve disc seating. However, many licensees have also learned from their own operating experiences and from followup discussions with the SOV manufacturer, that several different models of Target Rock angle-type SOVs used for isolation purposes are " uni-directional" i.e., they will experience undesired seat lifting when the backpressure (pressure at the outlet port shown in Figure
- 3) is only 2 to 5 psi higher than the upstream or inlet pressure.
As noted in Target Rock Manual TRP 1571 (Ref. 43), the manufacturer has been aware of this problem at nuclear plants since 1978.
However in the late 1970s time-frama, Target Rock developed an 50V for use as a bi-directional isolation valve (would not open spuriously due to high backpressures). Target Rock considered the spurious seat lif ting to be an Architect Engineer / Licensee " application problem"
--not an SOV problem.* The issue of uni-directional isolation SOVs is clearly addressed in some - but not all Target Rock SOV users manuals.
For example, Reference 42 noted that the uni directional qualities of the Target Rock angle-type SOVs are stated in Target Rock manual TRP 1571 (Ref. 41) i.e.
"Most solenoid valves because of the nature of the operation of the valve, will stop flow in only one (1) direction.
By design, upstream pressure acts on the top of the disc, forcing it onto its seat, thereby creating a tighter seal.
However, if downstream pressure rises above upstream pressure, the disc will tend to lift off of its seat, thereby allowing flow."
Since Target Rock considered the spurious opening of uni-directional SOVs to be an application problem, not an SOV problem, Target Rock did not issue any field service notifications to alert owners of the affected SOVs to this problem.
Plants that have experienced spurious openings of safety-related Target Rock angle-type SOVs are:
H.B. Robinson 2 (1980)
(unspecified number of SOVs)
ANO-1 (1985)
(2 SOVs)
ANO-2 (1985)
(2 SOVS)
River Bend (1986) & (1989)
Harris 1 (1987)
(2 SOVs)
Hatch 2(1988)
(12 SOVs)
The licensees' corrective actions were to re-orient the SOVs to assure 5
that they would operate properly during accident conditions.
Section 5.1.4.1 describes the most recent events which occurred at River Bend.
- Telephone discussion between T. D. Crowley, Target Rock Corporation, and H. L. Ornstein, USNRC, January 24, 1990.
PRELIMINARY CASE STUDY 20
5.1.4.1 Incorrect Valve Orientation at River Bend In April and May 1989, during testing conducted in response to NRC Generic Letters 88-14 (Ref 43), the River Bend station found ten Target Rock SOVs used in safety-related applications which would spuriously open during accident con-ditions upon loss of instrument air.
The opening of those uni-directional SOVs 1
would have resulted in the blowdown of safety-related accumulators and would
)
have prevented safety-related equipment from performing their functions as assumed in plant safety analyses (Refs. 42, 44).
For example:
(1) Spurious actuation of six uni-directional SOVs upon loss of instrument air would result in bleed-down of safety-related accum-ulators in the control building, the auxiliary building and the fuel building.
The licensee postulated that rapid depletion of accumulators in the control building (in 3.7 minutes) would pre-vent proper operation of building dampers and would adversely affect cooling of safety-related equipment, control room cooling, and control room air filtration.
Depletion of accumulators in the auxiliary building would affect building dampers resulting in the loss of cooling of safety-related switchgear.
Depletion of accumulators in the fuel building would affect building dampers and would impact air filtration and prevent the maintaining of a negative building pressure.
(2) Two uni-directional SOVs were found in the standby service water system (ultimate heat sink) which could spuriously open when subjected to accident cunditions to prevent removal of heat through the ultimate heat sink.
(3) Two uni-directional SOVs were found in the instrument air system which could spuriously open upon loss of instrument air.
Such opening would prevent long-term operability of all of the plant's (16) ADS /SRVs.
In Reference 42, the licensee also notW that several years earlier (1986) it had found three other Target Rock SOVs which had to be re-oriented due to i
spurious opening which was discovered when they were subjected to leak rate testing.
Those three SOVs had served as containment isolation valves in the containment hydrogen sampling system. The licensee did not consider that event to be reportable at that time.
5.2 Maintenance Representative operating experience illustrating maintenance problems associated with maintenance frequency, replacement versus rebuilding, contamina-tion, and lubrication are described below.
Based on this experience, findings and recommendations relevant to maintenance problems are provided in Sections 7.2 and 9.2 respectively.
PRELIMINARY CASE STUDY 21
5.2.1 Maintenance Frequency 5.2.1.1 Dresden 3 - BWR Scram System - Primary System Leak Outside Primary Containment During recovery from a reactor scram at 81 percent power on September 19, 1985, Dresden 3 experienced a leak of reactor coolant outside primary contain-ment.
The leakage path was through the scram outlet valves and the SDV vent and drain valves (Refs. 45,46,47).
The NRC issued Information Notice 85-95 to alert itcensees to the potential for reactor coolant leakage into the reactor building which could result from scram solenoid valve problems (Ref. 48).
The information notice indicated that a similar event had occurred at Dresden 2 in 1972; however, the licensee did not determine the root cause of that event.
Af ter the reactor scrammed in September 1985, the control room operators attempted to reset the reactor protection system (RPS).
WPS channel A was successfully reset, but channel B could not be reset.* This channel configura-tion allowed the scram pilot SOVs to vent air, resulting in reduced air header i
pressure.
The reduced air header pressure (38 psig) was sufficient to allow the SDV vent and drain valves to open (opening pressure s8 to 15 psig), but it was not sufficient to enable the scram inlet and outlet valves to reclose (+42 psig required to close).
For approximately 23 minutes, reactor coolant leaked outside primary containment into the reactor building.
The high temperature reactor coolant flashed to steam.
The leak resulted in elevated radiation levels on the first three floors of the reactor building.
In addition to the anomaly associated with the half scram configuration, degraded scram pilot SOVs contributed to the event.
Testing showed that leaking scram pilot SOVs resulted in a combined SDV air header leak of 25 scfm.
The licensee found widespread wear, aging, and hardening of the 50Vs' 0-rings and diaphrages.
Maintenance records showed that some of the worst leaking valves had been rebuilt during the previous refueling outage.
After a reactor scram, the SDV and the scram instrument volume are in direct contact with hot pressurized reactor water.
A common-mode failure of the pilot SOVs controlling the seram discharge system vent or the drain valves could result in an uncontrolled release of reactor water outside primary containment (see Figure 7) until the scram is reset.
Such an event occurred at Hatch 2 in August 1982 (Ref. 49).
Similarly, a sluggish SOV piloting an SDV drain valve caused a water hammer at Brunswick I which resulted in damaged pipe supports in the SDV drain system (Refs. 50, 51).
As noted in Reference 46, a severe water hammer in the SDV system could result in an uncontrolled leak of reactor water outside the primary containment.
Discussion with GE** has indicated that since Information Notice 85-95 was issued BWR owners have made improvements in their SDV systems so that there are redundant SDV vent and drain valves at all U.S. BWRs (vs. only one vent and one drain valve per SDV header in the early 1980's).
However, it is not certain that all U.S. BWRs have manual handwheel overrides for the SDV vent and drain valves to limit reactor water leakape outside primary containment in the event of a common-mode failure of the SOVs piloting the SDV vent and drain systems.
- Channel B remained tripped because of stuck contacts on the reactor mode switch.
l
PRELIMINARY CASE STUDY 22
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5.2.1.2 Perry - Simultaneous Common-Mode Emergency Diesel Generator Failures
)
On February 27, 1987, the Perry Nuclear Plant experienced simultaneous common-mode failures of both emergency diesel generators (EDGs) (Ref Sla).
The failures were attributed to excessive air leakage through SOVs on each EDG's control panel.
The SOVs were Humphrey Products Model No. TOG 2El-3-10-35 which were supplied by Delaval as EDG piece parts.
The SOVs are 3 way air control valves which are continuously energized while the EDGs are in standby.
The licensee had previously identified those SOVs for replacement due to observed air leakage. Work requests had been initiated for replacement of those S0Vs but at the time of their failures, the work requests had not yet been implemented.
Discussions with the licensee
- and the EDG manufacturer ** revealed the following information:
1 The failed SOVs had been in service for over 10 years.
2 The analysis of the SOVs found that the elastomeric parts (Buna-N) were " dried up and cracked" 3 The failure was attributed to long-term operation at elevated temperatures 4 The Humphrey valves were purchased by Delaval as com-mercial valves and were upgraded / dedicated for nuclear service by Delaval.
Delaval did not provide specific maintenance instructions for the SOVs.
5 The changeout frequency of the SOVs is not specified in the Delaval Operator's Manualj however, it could be implied from the manufactsrer s control panel environmental qualification report.
6 Although the SOV manufacturer das stated that SOV i
failures have occurred because of incorrect use of lubricants on the Buna-N parts, the licensee was not provided with any such instructions.
7 The Perry plant upgraded the SOVs to ones with Viton instead of Buna-N; and more recently they replaced the SOVs with electrical relays.
We are uncertain about the vulnerability of other 8
1 nuclear power plants having Delaval EDGs with Humphrey SOVs similar to the ones that failed at the Perry plant in February 1987.
5.2.2 Replacement Versus Rebuilding l
5.2.2.1 MSIVs at Perry - Inadequate SOV Rebuild After determining the cause of the MSIV failures of October 29 and Novem-ber 3, 1987, the licensee replaced or rebuilt the ASCO SOVs on the MSIV air packs.
Due to the limited availability and long lead tin.es for replacement
- Telecon H. L. Ornstein USNRC and R. DiCola, Cleveland Illuminating Co.,
May 29-30, 1990.
- Telecons H. L. Ornstein and D. Pesout and S. Owyoung, Cooper Industries (formerly Delaval) May 29-30, 1990.
PRELIMINARY CASE STUDY 24
--n
,------,n---
- --+<-
= -
i O
parts (air packs and ASCO dual-coil NP8323 SOVs), the licensee had to rebuild some (rather than replace all) of the MSIV air pack SOVs.
One entire air pack was replaced for the inboard D MSIV.
One dual-coil NP8323 SOV was replaced for the outboard D MSIV air pack.
One dual-coil NP8323 SOV was replaced for an inboard MSIV that had not failed previously.
It was replaced upon inspection because it was observed to have sustained heavy damage to the electrical coils due to moisture intrusion.
Five dual-coil NP8323 SOVs were rebuilt, including the inboard B MSIV which had failed on October 29, 1987.
The licensee conducted increased surveillance and testing of the MSIVs after repairing and replacing the air pack SOVs.
The licensee initiated monthly operability testing of the MSIV air pack SOVs, quarterly fast closure timing tests, and inspections of the ASCO NP8323 dual-coil SOV experiencing the high-est temperatures.
On November 29, 1987 while performing operability. testing, the ASCO dual-coilNP832350V,controllIngtheinboardBMSIV,failedtochangestatewhenit
.was de-energized.
Examination of the failed 50V found that the failure was caused by several foreign particles in the SOV.
Laboratory examination con-firmed that the particles were EPDM from the 50V's 0-ring which had been replaced during the 50V's rebuilding process subsequent to the November 3, 1987 failure (Refs. 8, 9).
Apparently, during the original SOV rebuilding process, the licensee did not completely disassemble the ASCO dual-coil NP8323 SOV.
As a result, one or more small particles remained in the valve and remained undetected until it (they) caused the 50V's failure.*
To preclude additional failures due to foreign particles remaining from the rebuilding process, as had happened on November 29, 1987, the licensee re-placed all eight ASCO dual-coil NP8323 SOVs with new ones.
Furthermore, the licensee stated that they were going to modify their preventive maintenance program: in the future, all Class 1E ASCO SOVs will either be replaced with new valves or undergo complete disassembly and cleanout to ensure that no omrticles L
remain or are introduced during the rebuilding process.
5.2.2.2 Brunswick 1 - Safety Relief Valves - SOV Rebuilding Error:
Excess Loctite On July 1,1987, while attempting to control pressure following an unplanned automatic reactor trip, an SRV failed to open on demand.
Following shut down, the licensee tested the SRVs that had not cycled during the trip recovery and found another SRV that did not open on demand (Refs. 52, 53).
The SRV failures were due to SOV failures.
The two SOVs that had failed (Target Rock Model 1/2-SMS-A01) are used to port air to the SRVs' actuators,
- It is believed that one particle remained in the 50V, and that the particle l
broke up during subsequent SOV operation.
L PRELIMINARY CASE STUDY 25 l
L
allowing remote-manual opening of the valves.
The two SRVs that failed were part of the plant's Automatic Depressurization System (ADS).
The failure of both safety relief valves to open on demand was attributed to excess Loctite RC-620, which was found in the internals of the related SOVs.
Although two additional valves were found to have excess Loctite on the 50V's internals, those valves did not exhibit signs of binding.
The licensee determined, with the assistance of the SOV manufacturer, that Loctite RC-620 had been used by the S0V manufacturer's field service representa-tive while rebuilding the SOV during'a previous outage.
In Reference 52, the licensee noted that the manufacturer s (Target Rock) field service representa-tive had rebuilt all of the Brunswick 1 SOVs that actuate all eleven of the plant's SRVs (seven ADS valves and four non-ADS valves).
The licensee stated i
that the Target Rock field service reprasentative had done 50V refurbishment work on the valves at Brunswick 1, but he had not done similar work on any SOVs which pilot SRVs at other plants.
Target Rock field representatives service the SRVs for all U.S. BWRs (except for Browns Ferry 1, 2, and 3) at Wyle Laboratories during the plants' refueling outages.
Most plants send their SRVs and SOVs to Wyle for refurbishment every refueling outage, but some only send half of their SRVs and SOVs to Wyle for such refurbishment each refueling outage.
The problem encountered with Loctite RC-620 was one of excessive applica-tion.
Loctite RC-620 is an anaerobic adhesive.
Curing takes place in the absence of air. The SOV manufacturer's refurbishment procedure specifies that Loctite RC-620 be applied to a locknut assembly beneath the valve plunger.
The l'
procedure cautions against apalication of excessive amounts of the adhesive.
The licensee concluded that t1e SOVs had excess amounts of Loctite RC-620 applied to them, and that curing did not occur until after the valves were placed in the inerted containment.
The licensee believed that, prior to curing, the excess adhesive migrated to the interior of the valves, bonding the 50Vs' plungers to the bodies of the valves.
The licensee concluded that even though only two ADS S0Vs vere found to malfunction, two other ADS SOVs had similar bonding due to excess Loctite RC-620; however, those bonds were broken during the initial removal and handling of the SOVs when they were removed from the drywell and bench tested.
The licensee's assessment of the event (Ref. 52) concluded that a common-mode failure, the inoperability of all 11 SRVs as a result of Loctite RC-620 bonding of all SOVs by one vendor field service representative, is a reasonably credible event.
The occurrence of a design basis event under such conditions is beyond the bounds of the plant's final safety analysis report.
The NRC staff issued Information Notice 87-48 (Ref. 53) to notify licensees of the July 1,1987 event.
A similar SRV failure occurred on July 25, 1980 at Pilgrim (Ref. 31).
A Target Rock SRV failed to open on a manual demand signal.
The failure was caused by excessive Loctite RC-620, which had caused the SRV's solenoid plunger to stick to the valve's bonnet.
In this case, the excessive Loctite was used during the fabrication of the SRV (as opposed to the July 1, 1987 event at Brunswick in which the excess Loctite was applied during refurbishing).
PRELIMINARY CASE STUDY 26 l
l
~
l 5.2.2.3 Peach Bottom 3 - Scram System - SOV Rebuilding Error:
Excess Loctite On November 17, 1983 a control rod was observed to have an excessive j
insertion time during a re, actor scram (Refs. 54, 55).
The sluggish control rod insertion was attributed to the failure of an 50V* to shift position to allow control air to be exhausted from the control rod's hydraulic control unit.
As a result, the licensee replaced the scram pilot SOVs associated with the control rod that did not scram promptly and sent the scram pilot SOVs to GE for failure analyses.
On January 14, 1984, during a reactor scram, another control red did not insert within the technical specification allowable time of 7 seconds.
The second control rod had acted sluggishly during the November 17, 1983 scram.
However, because it was believed to have inserted within the technical specifi-cation allowable time on November 17, 1983, no maintenance was performed on its pilot SOVs at that time.
Subsequent to the second failure (January 14,1984), the licensee undertook an extensive investigation.
That investigation revealed that, contrary to pre-vious findings, the second control rod also had failed to meet its allowable scram insertion time limit on November 17, 1983.
Laboratory analysis of the two pairs of SOVs associated with the slow 4
, inserting control rods revealed that one valve of each pair had a yellow varnish-like foreign substance on its core assembly.
One of the SOVs which was found to have the foreign substance on it exhibited sticking during subsequent bench testing. The foreign substance was originally believed to be a silicone lubri-cant, but it was later identified to be Lottite 242.
Loctite 242 had been intro-duced to the SOVs during the rebuilding process, in accordance with the supplier's (GE) recommendations.
In a 1978 Service Information Letter, (SIL) 128,-(Ref.
56), GE had recommended that when rebuilding CRD scram pilot valves Loctite 242 adhesive / sealant should be used to secure the " acorn nut" on the solenoid housing to prevent it from loosening.
The Peach Bottom 3 failures were attributed to excess Loctite 242 which was used in the rebuilding process.
It had appeared to be fully cured and the excess had not been wiped off.
When the system returned to service, the Loctite 242 migrated and hardened and bonded the S0V's core plunger to its base assembly.
After determining the source of the sticking, the licensee eliminated the use of Loctite 242 from its rebuilding process.
Subsequently, GE issued a supple-mentary service information letter, SIL 128 (Ref. 57) which recommended that all BWR owners discontinue using Loctite 242 or any other chemical adhesive thread lockers on the acorn nut of the pilot SOVs.
the " acorn nut"ginally recommended using Loctite 242 to overcome loosening of GE had ori
, and ASCO had agreed.
Following the sticking problems at Peach Bottom 3, ASCO made a design change and replaced the acorn nut with a nylon-lined locking nut which would not require adhesive thread lockers to remain tight.**
- ASCO Model HVA-90-405, which is built by ASCO but procured from GE, it is similar to the ASCO Model NP8316 valve.
- Telephone discussion between J. Shank, ASCO, and H. L. Ornstein, USNRC, June 19, 1989.
PRELIMINARY CASE STUDY 27
~
The common-mode failure potential for the scram system at some BWRs exists because some plants have used the same SOVs that are used to pilot the individ-ual control rod hydraulic control units to pilot the scram discharge volume vent and drain valves.
In the case of Peach Bottom 3, the potential for multiple simultaneous failure was compounded by the fact that the licensee had rebuilt all 370 control rod scram SOVs during the previous refueling outage.
To reduce this common-mode failure potential, GE's SILs (Refs. 56, 57) recommended (not a binding requirement) that CRD pilot SOVs be rebuilt on a staggered basis from a " distributed checkerboard pattern."
5.2.3 Contamination 5.2.3.1 Brunswick 2 MSIVs - Excessive Heat and Poor Air Quality (Hydrocarbons and Water)
On September 27, 1985, during surveillance testing at Brunswick 2, three of the plant's eight pneumatically operated MSIVs failed to fast close (Refs.
58,59).
There are two MSIVs in series in each of four parallel steam lines.
Two of the valves that failed to fast close were on the same steam line.
An investigation of the failures found that the MSIVs failed to close because of disc-to-seat sticking of the MSIV air pack SOVs (ASCO dual-coil Model NP8323).
The itternal 0-rings on the SOVs also were found to be degraded; they were j
brittie, and several 0-rings were stuck to the valve body.
Several 50V discs came apart after becoming brittle:
pieces of one 50V disc became wedged in the 50V's exhaust port, one disc stuck to the exhaust port, and another SOV lost a piece of its disc.
Laboratory analysis of the three failed SOVs showed the presence of a significant amount of hydrocarbon in them. The combination of hydrocarbons and elevated temperature caused the EPDM discs to swell and fill the 50Vs' exhaust ports, which blocked the discharge of air in the air actuator and increased the frictional force opposing SOV core mov:. ment.
The instrument air system was believed to have been the source of the hydrocarbon contamination.
Because of the susceptibility of the SOVs' EPDM parts to hydrocarbon contamination, the licensee replaced all of the SOVs with the same model SOV having Viton discs and seals.
Compared to EPDM, Viton is less susceptible to hydrocarbon contamination, but it is more susceptible to radiation damage.
This event was reported to Congress as an abnormal occurrence.
The abnormal occurrence report categorized the event as one which resulted in the
" loss of plant capability to perform essential safety functions such that a potential release of radioactivity in excess of 10 CFR Part 100 guidelines could result from a postulated transient or accident" (Ref. 60).
5.2.3.2 North Anna 1 and 2 - Multiple Systems - Oil and Water Intrusion While performing maintenance operations at North Anna in the morning on April 24, 1987, an operator error resulted in a service water intrusion into the Unit I and 2 instrument air systems (Refs 61-64).* The licensee quickly recognized that the service water intrusion affected SOVs and pneumatic con-trollers for auxiliary feedwater systems, primary and secondary pressure
- Telephone discussions between J. Lewis and J. E. Wroniewiez, Vepco, and H. L. Ornstein, USNRC, May 1989.
PRELIMINARY CASE STUDY 28 1
9
o control systems, and the SOVs required for containment isolation (" trip valves") for both Units 1 and 2.
At the time of the event, Unit I was in mid-loop operation and Unit 2 was I
operating at 100 percent power. The licensee's immediate response to the event i
was to continue operating Unit 2 and to blow down the affected instrument air lines.
About 2-1/2 hours after the intrusion occurred the licensee tested the Unit 2 "A" motor-driven AFW pump.
The air-operated discharge valve and the back-pressure regulating valve for the AFW pump both malfunctioned rendering the pump inoperable.
About three hours later the licensee tested pump B satisfactorily.
Throughout the evening of April 24, 1987, the licensee continued to blow down instrument air lines until no moisture was observed. The "A" AFW pump's discharge and pressure regulating valves were repaired on the evening of April 24, 1987 and were satisfactorily tested around midnight.
The cleanup procedure was not totally effective since there were low points in the instrument air system that had not or could not be drained.
The residual l
water that remained in th; low points of the instrument air system and the mois-ture and contaminants in ti.e instrument air system resulted in widespread SOV failures for almost two years after the service water intrusion event.
In addi-tion to failures of " freestanding" SOVs, there were dozens of control valve failures.
The bulk of the control valves that failed were Fisher control valves.
Integral to each Fisher control valve is an ASCO SOV.
The Fisher control valve failures were essentially failures of the ASCO SOVs which are piece-parts of the control valves.
Examination of plant equipment failure records noted that between April 1987 and February 1989, there were approximately fif ty Fisher control valve (ASCO SOV) failures.
It appears that those failures resulted from poor quality air due to the April 24, 1987 water intrusion event and from poor maintenance of the instrument air system.
In addition to these failure records, NRC inspectors noted (Ref. 62) many ASCO SOV failures that had been observed during surveillance testing after April 24, 1987, were not reported and the SOVs were not repaired.
The primary reason was that the SOVs that failed to operate during surveillance testing operated properly after being tapped (" mechanical agitation") by plant personnel.
l As a result of such practices, repetitive malfunctions were observed, the mal-l functioning SOVs were not fixed or replaced expeditiously, and the root causes were not found or corrected on a timely basis.
Characterization of the licen-see's in-service testing practices regarding SOVs was cited in Reference 61 as follows:
"The process of tapping on solenoid valves and repeated cycling of valves prior to running a satisfactory surveillance was considered an acceptable practice by the licensee."
Some of the systems that were affected by malfunctioning ASCO SOVs (freestanding or piece-parts of Fisher control valves) due to contamination of the instrument air system are listed in Table 2.
PRELIMINARY CASE STUDY 29
o Table 2 Systems Imp.cted At North Anna By SOV/ Control Valve Failures Due to Service Water Intrusion / Instrument Air Contamination
{
Unit I and Unit 2 i
Residual Heat Removal / Low Pressure Safety Injection Main Steam Relief (PORVs)
Auxiliary Feedwater Component Cooling Water Unit 2 only Containment Isolation Containment Fan Cooling Main Steam Isolation In a February 10, 1988 memorandum, the Chairman of North Anna Station's Nuclear Safety and Operating Committee stated that successful stroking of the SOVs is an appropriate corrective action to remove contaminants, because " cycling the affected valves blows the contamination from the lines and returns the SOVs to operable status" (Refs. 65, 66).
North Anna Station's approach to maintenance of malfunctioning SOVs contradicts the valve manufacturer's recommendations.
ASCO's installation and maintenance instructions and the licensee's telephone discussions with ASCO on February 4 and 5,1988 advised the licensee that, after SOV contamination, the NP Series SOVs should be inspected for corrosion, sadiment or other contaminants, and cleaned accordingly.*
A meeting was held at NRC Region II offices on February 7, 1989 to discuss repetitive AFW system control valve failures which occurred in January 1989, due to moisture in the instrument air system (Ref. 67).
At the meeting, the licensee acknowledged that widespread failures of SOVs, control valves and air-operated valves had occurred during the 21 months from the time of the service water intrusion into the instrument air system (April 1987 through January 1989).
A large number of repetitive SOV and control valve failures were attributed to i
poor quality instrument air (oil and moisture contamination in addition to the April 1987 service water intrusion).
The licensee noted that attention had been focussed on the quantity of instrument air available without paying attention to its quality and indicated that subsequent to a review of their instrument air system, a program was initiated to clean or replace the affected equipment.
The licensee also provided information on steps that were being taken to improve the j
instrument air system to assure delivery of clean, dry, oil free instrument air.
We view the April 24, 1987 service water intrusion into the instrument air system as a significant precursor event.
It resulted in widespread degra-i l
dation of SOVs, controllers, and air-operated valves that had the potential for disabling many systems needed to achieve safe shutdown.
If a design-basis event
- Telephone discussions between F. Maiden and W. Murray, Vepco, and K. Thomas, ASCO, February 4 and 5, 1988.
PRELIMINARY CASE STUDY 30
~ -- ~
~
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L.
e had occurred at Unit 2 on April 24, 1987 before removing the service water from g
the instrument air system, the operators ability to bring the plant to a safe shutdown could have been seriously impaired.
A large number of SOV and control valve failures occurred at Units 1 and 2 between April 24, 1987 and January 1989 as a result of water, corrosion products, and residue from the service water intrusion, and from impurities introduced by poor quality instrument air.
This event exemplifies the necessity for providing SOVs with clean, dry, oil free air, and the need to thoroughly clean and inspect the equipment if water or other contaminant intrusions occur.
5.2.3.3 Susquehanna 1 and 2 - Scram System:
Oil and Water Contamination J
The Susquehanna plants have experienced common-mode failures of SOVs that resulted in multiple failures of control rods to insert, slow insertion of multi-ple control rods, and repetitive failures of scram discharge volume vent and drain valves.
The SOV failu?es were linked to contaminants in the instrument air system (i.e., hydrocarbonc, water, and particulates) and high temperatures.*
Because both Susquehanna units share a common instrument air supply, the common-mode failure potential that existed for both unit 1 and unit 2 scram pilot SOVs also existed for the SOVs that actote both units' backup scram valves.
The backup scram valves are intended to p cvide diverse scram capability to protect against common-mode failures.
Although Unit 1 experienced the failures, the potential for such failures also existed at Unit 2; both units' scram and diverse scram systems were vulnerable.
The Susquehanna 50V failures illustrate the potential for multi-plant common-mode failures leading to events that are beyond the plant safety analyses (i.e. failure of multiple control rods to insert and unisolated primary leak outside containment via the scram discharge volume).
A summary of the Susquehanna SOV failures are described below:
1 On October 6, 1984, while Susquehanna 1 was operating at 60 percent power, two control rods failed to insert during individual rod scram testing.
Further scram testing revealed that a total of four rods would not insert and nine additional rods hesitated before inserting.
A similar event occurred previ-ously at Susquehanna on June 13, 1984, when several control rods hesitated momentarily before inserting (Ref. 68). -Two of the control rods that failed to insert on October 6 had not met the plant Technical Specifications scram time requirements on June 13.
The licensee did not become aware of the June 13 mal-functions until the October 6 failures were investigated.
The October 6 failures were attributed to common-mode contamination of the instrument air system.
The combination of contaminants (oil and/or moisture) and high temperatures (140'F) caused the SOV internals to degrade and become stuck.
The 50V polyurethane disc holder subassembly seats were found to be stuck to the 50V exhaust port orifice.
This prevented air from the scram inlet and outlet valve operators from bleeding off through the 50V exhaust ports, which prevented the scram inlet and outlet valves from opening.
- At Susquehanna each of the 185 control rods is piloted by one ASCO HV-176-816 SOV.
Many other BWRs' control rods are piloted by other model ASCO SOVs, but two per control rod.
The ASCO SOVs used in U.S. BWR scram systems are typically procured from GE.
PRELIMINARY CASE STUDY 31
Two independent laboratories examined the failed SOVs and concluded that the polyurethane parts degraded because of a combination of contamination in the instrument air and elevated temperature (Ref. 69).
The first laboratory (Franklin Institute) cited the failure mechanism as hydrolytic decomposition of the polyurethane seats due to a combination of moisture and elevated tempera-tures.
The second laboratory (GE) indicated that polyurethane seat failure was caused by contamination of the instrument air with a synthetic diester oil (SDO, which is a plasticizer).
Both Franklin Institute and GE recommended replacing the polyurethane seats with a seat material capable of operating at higher temperatures and having an improved resistance to contaminants.
The recommended material was Viton.
The licensee replaced all of the SOV polyurethane seats on Units 1 ad 2 control rods and all the backup scram valves.
About half of the 50V dites for the Unit 2 control rods had already been replaced in 1983 with Viton discs.
The licensee's investigation found that the SOV for the scram discharge volume vent and drain valves on Unit I had a polyurethane disc that also was susceptible to the same type of failure.
The SOVs for the vent and drain valves also were replaced with different SOVs having Viton discs.*
The October 6, 1984 scram system degradation at Susquehanna was reported to Congress as an abnormal occurrence (Ref. 70).
The NRC staff concluded that the event involved a " major degradation of essential safety-related equipment,"
and demonstrated the plant's susceptibility to common-mode failure.
The failure caused a reduction in "the required ' extremely high probability' of shutting down the reactor in the event of an anticipated operational occurrence" (Ref. 70).
Another scram discharge volume (SDV) system component failure attributed to contaminated air occurred at Susquehanna 1 on December 21, 1984 (Ref. 71).
Dur-ing surveillance testing, an 50V that controls the SDV vent and drain line isolation valves malfunctioned as a result of particulate matter that was lodged between the SOV's disc and seat.
As a result, the SDV vent and drain valves were stuck open.
Since the reactor was at power, if the SOV had failed to completely close after a scram, the potential for an unisolated primary leak outside containment would have significantly increased.
5.2.4 Lubrication 5.2.4.1 Multiple Plants - Manufacturing Error:
Residue-Producing Lubricant
- The Kewaunee nuclear power plant experienced three SOV failures on May 28, 1988 during surveillance testing (Ref. 72).
Two of the SOVs were redundant containment isolation valves piloting the reactor coolant drain tank discharge header isolation valves.
The third SOV that failed served as the pilot for the pressurizer relief tank makeup isolation valve.
All three failed SOVs were nuclear qualified ASCO NP8314 DC valves that piloted air-operated valves.
The were normally open, normally energized, and were designed to close (fail safe)y on loss of instrument air or electrical power.
The failures of the SOVs to
- The SOV chosen was a larger size, made by another manufacturer.
The original Unit 1 valve was undersized and the replacement made was the same as the one on Unit 2.
PRELIMINARY CASE STUDY 32 9
m..
..y___w
shift position upon de-energization were attributed to an amber-colored residue inside the 50Vs.
The residue was found at the location where the SOV core as-sembly (plug) contacts the SOV body (solenoid base sub-assembly) see Figure 4.
The failed SOVs had been in service about 18 months prior to their failure.
The local ambient temperature was about 110'F.
The licensee inspected two other ASCO NP8314 SOVs from the same manufacturing lot which were installed adjacent to the three SOVs that had failed.
They had been installed at the same time as the ones that failed, but were operated in the de-energized mode. The de-energized SOVs had performed satisfactorily.
The licensee assisted by two independent laboratories (Wyle Laboratories and Akron Rubber Development Laboratory) and ASCO conducted an extensive inves-tigation to determine the root cause of the failures.
On the basis of the investigation, the licensee and ASCO concluded that the 50V failures were most likely caused by the degradation of a lubricant (International Products Corporation, "P-80" rubber lubricant) which had been introduced during the manufacturing process.
P-80 is a water-based rubber lubricant used by ASCO personnel to facilitate SOV assembly.
Although P-80 was an approved lubricant for use at ASCO's manufacturing facility, its use for the assembly of the NP8314 SOVs was not an explicitly approved procedure.
P-80 product literature states that it provides " temporary sligperiness" for assembling rubber parts, and that it is absorbed into the rubber leaving no residue or harmful effect on the rub-ber." Subsequent to 50V assembly (using the P-80 lubricant), the SOVs were
. cleaned; however, minute amounts of the P-80 lubricant remained within the inter-nal cavities of the SOV.
From the laboratory results, it was concluded that the small amount of lubricant, remaining in the SOVs, migrated subsequent to ener-gization, and the heating, due to energization, degraded the P-80 to form the amber-colored sticky residue which caused the SOV malfunctions.
The investiga-tion discounted Dow Corning 550 lubricant as the source of the residue that had been found inside the NP8314 SOVs.
ASCO has discontinued using P-80 in the assembly of SOVs as a result of the investigation.
On October 18, 1988, ASCO issued a 10 CFR Part 21 notification regarding
..the potential failures of NP8314 SOVs (Ref. 73).
The notification accounted for 231 suspect SOVs that were sent to 17 U.S. LWRs, 76 suspect SOVs that were sent to sup)11ers who most likely shipped them to unspecified plants as piece-parts of otler equipment between 1981 and 1988, and 9 suspect SOVs that were sent to Franklin Research Center (FRC) in 1986.
The Fort Calhoun plant had received the largest number of suspect SOVs (79) in 1981.
Several of those SOVs failed at Fort Calhoun in 1981 and 1982.
Three of the SOVs that failed at Fort Calhoun were returned to ASCO for investigation.
ASCO's investigation of those valves, incident report IR 3604 - May 1982 (see NRC Vendor Inspection Report 99900369/88-01 (Ref. 74), noted that the failures were due to sticking caused by a varnish-like residue.
At that time, neither ASCO nor the Fort Calhoun licensee were able to identify the source of the " acrylate ester residue found on the plunger and sub-base assembly" of the energized NP8314 SOVs.
Fort Calhoun experienced a similar failure of another energized NP8314 SOV in March 1982.
It was cleaned and returned to service (Ref. 75).
The licensee stated that it would replace the internals of all the NP8314 S0Vs using new spare parts kits.
Subsequently, Fort Calhoun donated 10 ASCO NP8314 S0Vs that had been in continuously energized service for 18 months to FRC for use in an PRELIMINARY CASE STUDY 33
NRC sponsored SOV aging research program (Ref. 71).
FRC also purchased nine new NP8314 SOVs from ASCO, which were shipped in April 1986, to be used in FRC's tion)gingprogram{thoseSOVswerealsolistedinASCO's10CFRPart21notifica-50V a Six of FRC s purchased SOVs, which were under failed prematurely (failure to shift position) going accelerated thermal aging as a result of organic deposits ("stickysubstance").
After the deposits were " cleaned away" with acetone and the SOVs were reassembled, they performed successfully for the dura-tion of FRC's testing program.
FRC's report (Ref. 76) also noted that organic deposits were found in the NP8314 SOVs received from Fort Calhoun.
FRC believed that the sticky deposits that had prevented the SOVs from functioning were due to an organic compound that was introduced during the assembly of the valves; however, a detailed analysis and final determination of the source of the deposits were not aursued by FRC because of budgetary restraints of the program.
In the course of tie FRC's SOV aging research program, ASCO had been apprised of the sticking problem, however ASCO did not find the source of the residue (P-80) until after the Kewaunee failures in 1988.
The failures of the NP8314 SOVs indicate that P-80 was used to assemble the NP8314 SOVs as early as 1981 and as late as 1988.
A similar case, in which another SOV manufacturer used a lubricant to assist with SOV assembly, also resulted in subsequent SOV performance problems.
As noted in Reference 77, Target Rock Corporation used castor oil as a lubricant to facilitate the assembly of its two stage safety relief valves (SRVs).
After investigating several SRV failures, it was found that castor oil, which was used to lubricate silicone rubber 0-rings, caused swelling and accelerated degrada-tion of the 0-rings.
Subsequently, Target Rock discontinued using castor oil as a lubricant. DAG-156 lubricant (carbon particles suspended in an alcohol base) was used to replace castor oil.
We are not aware of any subsequent Target Rock SRV failures that have resulted from the use of DAG-156.
Target Rock informed the author of this case study during a visit to their facility hadused{mineraloils"tofacilitateSOVassembly. November 1988) that, paralleling th This practice was dis-continued in the mid-1980s and DAG-156 was chosen as a replacement for mineral oils.
5.2.4.2 Catawba:
Poor Quality Air and Lubrication with Vaseline The Catawba nuclear power plant experienced commor mode failures of EDG starting air system inlet valves (Refs. 78,79,80).
lne EDGs were manufactured by Delaval.
The air start system inlet valves, model T-3618, were made by California Controls Co. (Calcon).
These two-stage air-operated valves each l
have a solenoid pilot valve that is normally closed and requires de power to l
actuate the solenoid pilot to admit starting air into the EDG.
l The licensee has reported five instances of common-mode failure of these valves.
The valves stuck open when a sticky, slimy substance formed inside the i
poppet portion of the valve.
The licensee determined that the substance was the silicone lubricant Dow Corning 111 that was used on the valves.
On five occa-sions, the licensee cleaned the valves and replaced the Dow Corning 111 with Vaselinepetroleumjelly.
Calcon's recommended lubricant is GE Silicone fluid G-322-L, which is significantly different from DOW Corning 111.
The licensee PRELIMINARY CASE STUDY 34
- -, ~,,,.
_,,,_.m
o didnotcheckforthecompatibilityofVaselinepetroleumjellywiththeBuna-N rubber used in the Calcon Valve.
Low nitrile Buna-N rubber degrades when in contact with petroleum based products.
After reviewing the EDG air start valve failures and other EDG pneumatic equipment failures (Calcon pressure sensors) the licensee concluded that the sticking was caused by moisture interacting with the Dow Corning 111 silicon lubricant.
The source of the moisture was the starting' air system, the root cause was inadequate dryer maintenance (the licensee s failure to changeout the spent desiccant).
Subsequently, the licensee upgraded its maintenance on the air dryers, thereby lowering the starting air moisture content.
In addition, the licensee cleaned the valves and replaced the Vaseline petroleum jelly with Dow Corning 111 lubricant.
Theseactionsinconjunctionwithmorefrcquentchangeoutof the Calcon gas valve's elastomeric parts in accordance with the Delaval owners' i
grou] plant specific recommendations appear to have eliminated the valve sticking problem.
5.2.4.3 Common-ModeFailureof16MSIVsataTwoUnitStation(BWRs):
Incorrect Lubrication In July 1986, the licensee of a two-unit station reported excessive stroke time of the Unit 1 "C" outboard MSIV which resulted from a failure of an Auto-matic Valve Corporation (AVC) SOV (model C4988-8).
The failure was attributed to " poor workmanship from the factory" and " improper lubrication, which would allowthevalvepistontojamatacertainplaceinthevalve." The failed AVC valve was replaced with a new one.
Five months later (December 1986) while performing monthly closing tests, the licensee found that the Unit 2 "B", inboard MSIV did not stroke properly as a result of a failure of another AVC SOV.
The licensee shut down both units from 100 percent power and inspected the SOVs piloting all 16 MSIVs.
The l
licensee found that the AVC SOVs on all 16 MSIVs were damaged.
The three-way and four-way valves and solenoid pilot valves on all 16 MSIVs had a hardened, sticky lubricant in their ports and on their 0-rings.
As a result, motion of all the SOVs was im) aired, resulting in instrument air leakage and the inability to operate all of tie MSIVs satisfactorily.
The licensee also examined unused spares in the warehouse and found that the lubricant had dried out in those valves, leaving a residue.
Several of the warehoused spares were bench tested.
They were found to be degrabed and they also leaked.
The original " approved" or " preferred" S0V lubricant (based upon equipment qualification testing) was Parker Super-0-lube.
However, later equipment quali-fication testing (1985) found that the Parker Super-0-lube could cause SOVs in the MSIV air pack to malfunction.
The Parker Super-0-Lube was found to breck down to an adhesive, powdery substance when exposed to radiation fields greater than 1x10E6 RAD.
Because of the potential for breakdown of Parker Super-0-lube and binding of the SOVs in the air packs, the licensee changed the SOV lubricant to E. F. Houghton SAFE 620.
In separate telephone conversations the SOV manufacturer (AVC) told the AE00 staff that it had informed the utility that E. F. Houghton SAFE 620 PRELIMINARY CASE STUDY 35
t lubricant attacks and degrades the aluminum in the AVC valves.* Nonetheless, in accordance with utility purchase orders, AVC shipped SOVs lubricated with E. F. Houghton SAFE 620 to two different utilities.
After the multiple failures occurred in December 1986, General Electric (GE) informed the licensee that the Parker Super-0-Lube is an acceptable lubricant "if it is applied in a ' thin film'." AVC and GE had concludea that the problem experienced with Parker Super-0-Lube in the 1985 qualification testing was due to " excess lubricant."
On December 19, 1986, AVC issued a 10 CFR Part 21 notification (Ref. 81).
The notification indicated that Commonwealth Edison had also purchased AVC valves lubricated with E.F. Houghton SAFE 620.
Commonwealth Edison told AE00 staff **
that the AVC valves which contained E. F. Houghton 620 lubricant were replace-ments for older model AVC SOVs which had been discontinued.
Before being noti-fied by AVC of the problem with E. F. Houghton SAFE 620 and befoie installing the valves, Commonwealth Edison replaced the SAFE 620 with Dow Corning Molykote 55M.
The licensee had recognized that Parker Super-0-Lube was the lubricant that had been used in earlier equipment qualification testing, and SAFE 620 was probably not an acceptable replacement.
Justification for the use of Molykote 55M instead of Super-0-lube was based upon the licensee's engineering analysis that indicated the similarities between Molykote 55M and Super-0-lube.
In retrospect, a detailed examination of these two lubricants reveals they may have very different high-temperature behavior and, under similar operating conditions, the Holykote 55M would be more suscepti-ble to dryout.*** Because of these differences, it is not clear that Molykote 55M is an acceptable " qualified" replacement for the Super-0-lube.
With regard to problems of excessive lubricant and the application of " thin films" of lubricant, it is interesting to note that a Commonwealth Edison plant had sticking problems with a similar AVC S0V several years earlier.
In that case, the sticking was attributed to not having enough lubricant applied to the AVC valve.
5.2.4.4 Grand Gulf 1, LaSalle 1, and River Bend MSIVs - Sticking SOVs - Foreign Unidentified Sticky Substance (FUSS) - I.ubricant Suspected l
l Between February 1985 and December 1989, the Grand Gulf 1 LaSalle 1 and River Bend nuclear power plants experienced sticking of ASCO dual-coil 8323 SOVs in the MSIV air packs (Refs. 8, 82 to 88).
The SOV malfunctions were attributed to a sticky substance at the contact point of the plug nut / core assembly inter-face (see Figure 1).
The SOV malfunctions impaired or prevented the MSIVs from closing within the times specified in the plant safety analyses.
l
- Telephone discussions between T. Hutchins, Automatic Valve Corporation (AVC) and USNRC (S. Israel - October 14, 1988 and H. L. Ornstein - April 12,1989).
- Telephone discussion between M. Sievert, Commonwealth Edison Company, and H. L. Ornstein, USNRC, April 12, 1989.
- Super-0-Lube consists of high molecular weight silicones whereas Molykote 55M is a lighter weight methyl silicone oil thickened with lithium soap having a lower dropping point than Super-0-Lube (where dropping point is an indication of the temperature limit at which the lubricant dries out).
PRELIMINARY CASE STUDY 36
l In the case of LaSalle, it was demonstrated that the cohesive / adhesive force 4
caused by the foreign sticky substance between the plug nut and the core assembly of an ASCO dual-coil NP8323 SOV was significant and could have been the cause of its failure.
After the core assembly was held vertically, the plug nut was pressed against the core assembly, and then the plug nut let go, the adhesive forces from the foreign substance between the two surfaces were able to support the weight of the plug nut to prevent it from falling."
Because the licensee suspected the Dow Corning 550 lubricant (ap)1ied to the SOVs internals at the factory) to be the cause of the sticking, tie licensee considered removing the factory installed lubricant from the 8 new NP8323 SOVs that were installed after the December 16, 1987 failure.
In consideration of ASCO's concern that, without the internal lubricant, ac powered SOVs could suffer fretting damage, the licensee installed the 8 new NP8323 Viton SOVs as thev were received from the manufacturer (without removing the lubricant).
Those 8 replacement SOVs have operated successfully through 1989.**
Subsequent to the September 30, 1988 failures of two ASCO dual-coil NP8323 SOVs at River Bend, the licensee replaced all 8 dual-coil NP8323 SOVs with new ones.
However, prior to installing the new SOVs the licensee removed the fac-tory coated lubricant (Dow-Corning 550) from thelt internal metallic parts.
On December 1, 1989 two of those replacement SOVs failed due to sticking.
The licensee attributed the sticking to FUSS which was believed (but not confirmed by laboratory analysis) to be Dow Corning 550 lubricant.
In following up the December 1, 1989 failures, the licensee reviewed the procedures which were used in September 1988 to remove the factory applied lub-ricant.
The licensee's review of those procedures indicated that although the Dow Corning 550 lubricant was removed from the internal metallic parts of the SOVs, the cleaning and reassembly procedures included a step in which the elastomeric parts of the SOVs were relubricated with the same Dow Corning 550 lubricant.
Because there was more FUSS on the cleaned SOVs that failed in
-December 1989 than on the factory assembled SOVs that had failed September 1988, the licensee believed that the root cause of the December 1989 failures was the licensee's reapplication of excessive lubricant during the 50V cleaning and reassembly process.
Subsequent to the December 1, 1989 failures the licenseo's corrective action was to replace all eight NP8323 dual-coil SOVs with new ones -- after removing all the factory applied lubricant from them, without relubricating the elastomeric parts.
Table 3 summarizes events where MSIV air pack SOVs have stuck at Grand Gulf, LaSalle, and River Bend.
- According to ASCO, the plug nut weighs about one ounce while the spring force is about two pounds.
ASCO indicated that after a similar NP8323 SOV failure at WNP 2, thi. licensee had performed a similar demonstration.
The sticky sub-stance at WNF2 was believed to be from excess lubricant (Dow Corning 550) that had been applied by the licensee when the SOVs were rebuilt.
PRELIMINARY CASE STUDY 37
- g Table 3 MSIV Air Pack 50V F9
- s (ASCO Dual-Coil 8323)
~
5 utner SOVs Having g
Description Number of Foreign Unidenti-4 Plant / Event of 50V and Stuck SOVs fied Sticky Date Corrective Action and Location Substance (FUSS)
Comments n?
Grand Gulf 1 ASCO HTX8323* (Viton).
2 outboard All others (5)
In subsequent testing at ASCO m
2/10/85 Replaced all 8 SOVs with lines (A and only 1 of 4 additional valves 8
ASCO NP8323 (having EPDM C) 1 inboard malfunctioned (leakage).
parts). See Section (D line)
However the failure of the 5.2.1.1 for a discussion outboard C-line 50V was of the subsequent fail-attributed to FUSS at the ures of the replacement plug nut / core assembly valves caused by themal interface.
aging from self-heating (August 1989)
LaSalle 1 ASCO NP8323 (Viton).
1 outboard All others (7) 3 of the valves that did not 12/16/87 Replaced all 8 SOVs (C-line) fail in the plant, failed
.m with like.
during subsequent testing at ASCO, due to presence of FUSS at the plug nut / core assembly interface.
River Bend ASCO NP8323 (EPDM).
Re-2 inboard One unfailed Not all SOVs have been 9/30/88 placed all 8 SOVs with lines (B and inboard 50V inspected. Some are being like - attempted to re-C) (1 in-inspected was held for archival purposes.
move the factory coated spected, FUSS found to have lubricant (Daw Corning.
found)
FUSS.
i 550) from SOVs, but ap-Two outboard Two outboard SOVS were in-plied excessive amount SOVs inspected spected at ASCO. The coil of lubricant to 0-rings found to have enclosures of both SOVs had while reassembling FUSS.**
had evidence of moisture caused 2 subsequent intrusion, indicative of failures (December 1989) localized steam heating.**
- ASCO HTX 8323 is not a nuclear qualified 50V, it is a non qualified commercial valve similar to the NP8323.
- Telephone discussion between J. Shank, ASCO, and H. L. Ornstein, USNRC, May 8, 1989.
s.
- g Table 3 MSIV Air Pack SOY Failures (ASCO Dual-Coil 8323) (continued)
P EE Other SOVs Having y
Description Number of Foreign Unidenti-Q Plant / Event of 50V and Stuck SOVs fied Sticky Date Corrective Action and Location Substance (FUSS)
Comments nR m
River Bend ASCO NP8323 (EPDM) 2 outboard 1 other 50V was Licensee believes FUSS from 12/1/89 Replaced all NP8323's lines (A and inspected (in-was from excessive application 8
with new ones--but D), FUSS found board), It also of Dow Corning 550 which was removed factory or both had FUSS, but used by the licensee when installed lubricant less than what lubricating the 0-rings sub,
from all internal was found on the sequent to removing the Dow parts of the SOVs.
failed outboards Corning 550 from the 50Vs' internal metallic parts subsequent to the 9/30/88 failures.*
- Telephone discussion between V. Bacanskas, River Bend, and H. L. Ornstein, USNRC, December 12, 1989.
t 1
t
The inspection of the SOVs on the inboard and outboard MSIV air packs at all three plants indicated that in almost every case the SOVs, which had not failed, were degraded in a manner similar to the failed SOVs, but to a lesser degree.
In each case, the licensee recognized the common-mode failure potential for compromising fast closure of inboard and outboard MSIVs on one or more steamlines and replaced all the 8323 SOVs on the inboard and outboard MSIV air packs.
The valve manufacturer and several laboratories conducted extensive inspec-tions and tests on the 8323 SOVs which had been replaced. There are no simple explanations for these failures individually or as a group. The source (s) of the sticky substance (s) which resulted in multiple 50V failures is uncertain.
There is major disagreement between the utilities, the SOV manufacturer, the reactor manufacturer and the laboratories regarding the root causes of the i
failures.
Internal 50V lubrication (by the manufacturer and in one case by the licensee), and poor air quality are primary suspects.*
5.3 Surveillance Testing 5.3.1 Control Rod Timing Tests - Failed Scram Pilot SOVs - Perry l
On July 22, 1989, during scram time testing, plant personnel observed two control rods failed to meet their scram time testing requirements on initial attempts -- however, when retested the rods operated satisfactorily.
As a result, both control rods and their SOVs were declared to be operable.
Subse-quently, on November 25, 1989, one of those rods failed its timing test twice but was retested satisfactorily twice.
As a result, it was declared operable.
When the second control rod that had also failed twice on July 22, 1989, was retested on November 25, 1989, and failed, it was declared inoperable.
At that time, the licensee conducted an investigation to determine the root cause of the test failures (Refs. 89,90,91).
The licensee's root cause analysis found that a manufacturing error had been made at ASCO (failure to upgrade polyurethane seats of the scram pilot SOVs with viton), and that the Perry (Plant had not responded to a product recall notice that ASCO had sent them Ref 91).
It is significant that the licensee's surveillance testing program did not provide guidance to the plant staff regarding actions to be taken when unsatisfactory test results are encountered.
5.4 Use of Non-Qualified SOVs 5.4.1 Colt /Fairbanks-Morse EDGs: Repetitive Air Start Valve Failures One plant, having Colt /Fairbanks-Morse EDGs, experienced six air start SOV failures during an 8 year period.
There were five failures of one valve and one failure of an identical, redundant SOV.
The SOVs were commercial grade valves, model X833-134, made by ASCO.
The failures occurred from February 1, 1980, i
- Failures of ASCO NP8314 SOVs which are geometrically similar to the 8323 SOVs have been traced to an assembly error during manufacture.
Conceivably, a t
l similar error may have been introduced during the assembly of the 8323 SOVs (see Section 5.2.4.1).
PRELIMINARY CASE STUDY 40 l
l
through March 28, 1988, and in each case the failures involved excessive air leakage.
Four of the five failures of the same valve (DA-198) were attributed to the 50V core and spring assembly.
The first failure was attributed to wear of the core and spring assembly caused by excessive heat from the solenoid being constantly energized.
The 50V was rebuilt (core and spring were replaced).
The SOV's second failure was attributed to " wear of the core and spring assem-bly." The 50V was rebuilt again (core and spring assembly were replaced). The third malfunction of the same 50V occurred while attempting to start the diesel.
The failure was attributed to " misalignment of solenoid header due to previous repairs." The licensee's corrective action was to realign the solenoid header.
Three months later the same 50V was again found to be leaking air.
This fourth failure was attributed to " wear of the core and spring assembly." The 50V was rebuilt again (core and spring assembly were replaced).
Five months later a redundant air start SOV (DA-23B) on the same diesel was found to be leaking air.
It was rebuilt (spring and core were replaced).
On March 28, 1988 the same SOV that had failed four times before (DA-198) failed again.
The fifth failure was attributed to a worn seat that resulted in air leakage.
The valve was replaced rather that being rebuilt.
We are unaware of any subsequent failure of this replaced SOV.
Discussions with the licensee who's EDGs experienced these six failures, and other licensees with Colt /Fairbanks-Morse EDGs indicated that they have received little, if any guidance from the EDG supplier about preventive mainte-nance or replacement of the air start system SOVs.
The SOVs that are used for the Colt /Fairbanks-Morse EDGs are commercial grade ASCOs which are supplied with limited maintenance or service life information.
l
^
l i
i PRELIMINARY CASE STUDY 41 r
l 6
ANALYSIS AND EVALUATION OF OPERATIONAL EXPERIENCE 6.1 Common-Mode Failures Examination of the events discussed in Chapter 5 and many of the SOV failures included in Appendix A clearly indicate a potential exists for common-mode 50V failures that could compromise multiple trains of diverse safety systems.
Such common-mode failures are not considered in plant safety analyses.
It is not practical to perform safety analyses for all combinations of common-mode SOV f ailures.
However, it.is feasible to take actions to minimize the likelihood for encountering common-mode SOV failures that could affect safety systems.
Chapter 9 presents recommendations that can be effectively used to minimize the potential for common-mode SOV failures affecting safety systems.
The root causes of many common-mode SOV failures that have been observed thus far are given below.
(1) Design / Application Deficiencies Incorrect specification of operating parameters such as M0PD (e.g.,
Section 5.1.3.1) and valve orientation (e.g., Section 5.1.4.1);
incorrect material selection such as incompatibility between SOV internal parts and fluids in contact with the SOV (e.g., Section 5.2.3.3);
incorrect specification of ambient (non-accident) conditions (i.e.,
temperatures, radiation, and moisture) (e.g., Sections 5.1.1.2, 5.1.1.3);
incorrect assessment of the life shortening effects of coil heating (e.g., Sections 5.1.2.1,5.1.2.2).
(2) Inadequate Maintenance Failure to replace or rebuild limited life piece parts of the SOVs (e.g., gaskets, seals, diaphragms, springs, and coils) on a timely basis (e.g., Sections 5.2.1.1,5.2.1.2);
failure to rebuild SOVs correctly (e.g., Section 5.2.2.1);
failure to maintain clean, dry instrument air.
Contaminants have caused long-term common-mode 50V degradation and failure (e.g.,
Sections 5.2.3.1,5.2.3.2);
excessive lubrication of SOV internals have contributed to 50V failures (e.g., Section 5.2.4.3).
(3) Installation Errors j
Incorrect orientation (backwards, upside-down) installation at an angle not in accordance with SOV qualification testing (e.g.,
Section 5.1.4.1, Appendix A);
l PRELIMINARY CASE STUDY 42
i incorrect electric current (de vs. ac) (e.g., Appendix A);
inadequate terminal or 1 unction box connections as a result of inade-quate manufacturer's guldance or architect engineer's interpretation of manufacturer's guidance (e.g., Appendix A).
(4) Manufacturing Defects Lubrication errors (e.g., Section 5.2.4.1);
defective materials - body, plug, springs, elastomers (e.g., Ref. 74);
tolerance / assembly errors such as incorrect spring size or stiffness (e.g., Ref. 74, Appendix A);
faulty wiring / coil defects (e.g., Appendix A).
6.2 SOV Failure Rates It is difficult to accurately quantify SOV failure rates due to the following reasons:
(1) Not all 50V failures are documented.
In many cases SOVs are viewed as expendable items, installed without any failure reports.and their failures ar replacements are l
(2) Many SOV failures not associated with reactor trips or complete train fail-ures of safety systems are not reported in the LER data base, j
(3) Many SOVs that are subcomponents or piece parts of other larger components or systems are not always re)orted as SOV failures in the nuclear plant reliability data syste.n (NPR)S) for example, MSIVs, flow regulators, gov-ernors that fail to function properly because the related S0Vs have failed are unlikely to be reported as SOV failures.
Hence, an accurate estimate I
of 50V failure rates from NPRDS is not achievable.
Coupling the difficulties of obtaining accurate SOV failure counts with the difficulty of accurately assessing the number of successful SOV challenges or surveillance tests can, at best, lead to a crude estimate of SOV failure rates.
Nonetheless, Table 4 lints S0V failure rates from several sources, including the results of this study's query of the NPRDS data for failures which occurred from January 1,1985 through December 31, 1988.
l It is significant that assuming quarterly testing of SOVs, NPRDS data, for the years 1985 through 1988, indicate failure rates of 7 to 9.5 times higher than the estimates used in WASH 1400 and in the NUREG 1150 methodology.
Exem-plary of item (3) above, the NPROS failure records used for estimating SOV failure rates generally do not include the unrecognized S0Vs.
l l
It should be noted that publicly available SOV failure rate data does not distinguish between SOV size, energization mode, valve opening status, manufac-turer, model, or type.
in view of the wide range of SOV variations, the avail-able failure data does not allow for accurately predicting individual SOV performance or failure rates.
PRELIMINARY CASE STUDY 43 e
5 Table 4 Estimates of SOV Failures to Operate j
i Estimated Source failure rate WASH 1400 1x10 8/ demand This study 7 to 9.5x10 8/ demand (NPRDS data Jan 85-Dec. 88) i Assuming quarterly testing NUREG 1150 methodology NUREG/CR 4550 Vol. 1 1.0x10 8/ demand (SeabrookPRA) 2.4x10 8/ demand NUREG/CR 4550 Vol. 6 1.6x10.s/ demand (Grand Gulf PRA)
NUREG/CR 4819, Vol. 1 7x10.s/hr (NPRDS data Sept 78-July 84)
This study 6.4 to 8.7x10 8/hr (NPRDS data Jan 85-Dec. 88) i In view of the aforementioned problems of estimating single 50V failure rates, we find the task of estimating the risk resulting from common-mode 50V failure to be a difficult task the results of which may have significant uncertainty.
SuchanundertakIngisbeyondthescopeofthepresentstudy.
We know of no PRA which accounts for the contribution of common-mode fail-ures of SOVs.
Omission of such cross system / cross train failures lead towards nonconservative results.
6.3 Maintenance Problems 6.3.1 Maintenance Problems - SOV Manufacturers' Contributions Review of operating experience indicates that a substantive number of SOV failures are attributed to inadequate maintenance or refurbishment.
As evidenced by several of the events discussed in Chapter 5, it is clear that utilities are not fully informed of SOV maintenance requirements.
Theneglectoroversightof SOV maintenance oftentimes comes from the SOV manufacturers failure to provide 50V maintenance requirements to the 50V users or second-level manufacturers--
such as EDG manufacturers (ALCO, Colt /Fairbanks-Morse, General Motors Delaval, Cooper-Bessemer), valve manufacturers (Xomox), controller manufacturers (Fisher, Masoneilan),etc.
Some SOV manufacturers are more prescriptive than others.
Some manufacturers provide no guidance on preventive maintenance.
One manufac-turer (Valcor) varies its recommendations depending on whether the purchaser bought the " full documentation package."
J PRELIMINARY CASE STUDY 44
n
Examples of the variation among SOV manufacturers' maintenance recommenda-i tions are discussed below.
ASCO does not provide any specific recommendations for 50V maintenance or refur-Eishment.
This is even true for their nuclear qualified IE valves. Quoting ASCO's installation and maintenance bulletin for NP8323 SOVs (Ref. 92).
i
" Preventive Maintenance 1.
Keep the medium flowing through the valve as free from dirt and foreign material as possible.
Use instrument quality air, oil-free for Suffix "E."
2.
Whi". in service, operate valve periodically to irsure l
proper opening and closing.
3.
Periodic inspection (depending upon medium and service conditions) of internal valve parts for damage or exces-l sive wear is recommended. Thoroughly clean all parts.
Replace any parts that are worn or damaged, i
4.
The valves may require periodic replacement of the coils e d all resilient parts during their installed life to maintain qualification.
The exact replacement will depend on ambient and service conditions. period Spare parts kits and coils are ordered separately (see Ordering Information).
Consult ASCO for specific recommendations in connection with the replacement of parts."
Valcor provides specific recommendations for maintenance or refurbishment of its N-stamped SOVs.
However, it is possible to purchase the same valve without an N stamp.
If it is purchased without an N stamp, it can also be purchased l
without any documentation.
Such a "no-doc" valve would not be provided with any preventive maintenance or refurbishment recommendations.
Target Rock - All of Target Rock Corporation's SOVs appear to be supplied with specific preventive maintenance and refurbishment recommendations.
1 I
Circle Seal, Ross and an Unspecified Foreign Manufacturer - Circle Seal and Ross make SOVs which are used in several different EDG air start systems.
Those valves are not supplied with any preventive maintenance or refurbishment l
recommendations.
Lack of specific maintenance recommendations has contributed I
to multiple failures of a foreign manufacturer's SOVs used in the EDG air start system of a foreign plant (see Section 6.3.2.1).
Skinner Electric - SOVs manufactured by Skinner Electric Company which are used I
in Woodward Governors on BWR HPCI turbines are not provided with any preventive maintenance or refurbishment recommendations.
Sperry-Vickers - SOV's manufactured by Sperry-Vickers which are used in the hydraulic controllers used for BWR recirculation pumps and main turbine-trip systems are not provided with preventive maintenance or refurbishment L
recommendations.
1 PRELIMINARY CASE STUDY 45
+
6.3.2 Maintenance Problems - Contribution of the Unrecognized SOVs In many cases plant maintenance and operations personnel are unaware of the presence of, or maintenance requirements of SOVs.
This situation is common be-cause there are many cases in which SOVs represent only a small portion of a larger system or component, and the information available to plant staff does not identify the care required by the SOV which is " unrecognized" within the "overall system".
Examples that we have observed are:
air start systems, governors, and cooling water control systems.
Auxiliary feedwater and main feedwater systems:
flow control regulators.
BWR high pressure cooling injection systems:
remote shutoff controls, governors.
Instrument air dryers:
desiccant column regeneration and cycling control systems.
6.3.2.1 Unrecognized SOVs in Emergency Diesel Generators The operation and maintenance manuals for the plants diesel engines, and operator and maintenance personnel training are heavily weighted by the engine manufacturer's literature which, at best, includes minimal information regarding the SOVs used in the EDG's auxiliary systems.
Specific examples observed included:
A foreign reactor site where the air start SOVs were not on any preventive maintenance program.
Failure of one SOV due to aging of a Buna-N diaphram was undetected until its redundant backup failed from the same cause.
As a result, the station added refurbishment or changeout of such resilient parts to all its EDG air start systems.
Similar failures have been observed at numerous U.S.
plants, e.g., Three Mile Island 1* (Refs 93, 94), Ginna (Refs. 95,96,97),
Duane Arnold (Ref 98).
i During a trip to the Duane Arnold plant in reviewing SOV experience, l
l AE00 staff learned that subsequent to the July 1982 failure (Ref. 98), the Duane Arnold staff recognized the 50V's limited lifetime and tae need for SOV refurbishment or replacement.
As a result the Duane Arnold scaff added SOV i
changeout to-their preventive maintenance program.
However. several years later, plant maintenance personnel made a decision to eliminate changeout of that SOV from their preventive maintenance program.
The rationale for dropping such pre-ventive maintenance was that the 50V was cycled only 7 seconds a month, and such limited use did not seem to require maintenance.
The basis for implementing the SOV's preventive maintenance and the previous failure, which resulted from age related degradation, appeared to have been forgotten.
Subsequently, the licensee stated that preventive maintenance on the aforementioned SOVs would be reinstated.
As a student in a recent TVA EDG training course applicable to seven plants, (Browns Ferry 1, 2, 3, Sequoyah 1, 2, Watts Bar 1, 2) the case study author learned that maintenance literature for the General Motors Electro-Motive Division (GM-EMD) diesel engine supplied by Morris-Knudsen, does not provide the licensee with any instructions for refurbishment or changeout of the SOVs in the EDGs' air start and governor control systems.
- Telephone discussion, M. Schaefer, General Public Utilities, and H. L. Ornstein, USNRC, February 16, 1989.
PRELIMINARY CASE STUDY 46 l
4 6.3.2.2 Unrecognized SOVs in Auxiliary and Main Feedwater Systems As noted in Section 5.2.3.2, a review of failure data at North Anna Units 1 and 2 showed that poor quality air was the root of the SOV/ control valve fail-ures. As a result, the licensee initiated a program for repairing and replacing the SOVs and control valves, as well as upgreding the air system quality and enhancing plant personnel training and maintenance practices.
6.3.2.3 Unrecognized SOVs in BWR High Pressure Coolant injection Systems In Reference 99 the Duane Arnold alant's licensee reported the failure of the remote shutoff control system whic1 is part of the HPCI turbine's governor system.
Discussion with plant personnel and the turbine manufacturer indicated a lack of communication between them regarding the potential for undetected fail-ures of the SOVs.
The licensee's report noted that the failure was caused by aging of the elastomeric parts of the 50V.
Such an undetected failure could result in failure to start the HPCI system.
Apparently information provided by the turbine manufacturer (Dresser-Rand, formerly Terry Turbine) did not pro-vide adequate maintenance information about the SOV that is supplied as an internal part to the Woodward Governor (the SOV was manufactured by Skinner Electric Co.).
The Skinner Electric maintenance instructions do not address preventive maintenance or service life requirements for the SOV.
The Woodward Governor service manual does not address SOV preventive maintenance, or service life.
The service informatior. letters (SILs) provided by the NSSS vendor (GE) did address other aspects of HPCI turbine service, performance and maintenance, but discussion with plant personnel and GE personnel indicated that maintenance, refurbishment or replacement of the S0Vs are not addressed in any of GE's SILS.
6.3.2.4 Unrecognized SOVs in Instrument Air Oriers Review of a leading instrument air drier manufacturer's operation and l
maintenance manual indicated minimal guidance with regard to SOV maintenance.
The SOVs are required to cycle every five minutes to ensure that the air flows through the correct desiccant stack to assure proper air drying and acceptable outlet dew points.
Failure of the S0Vs could result in undetected high instru-ment air moisture content which could lead to degradation and malfunction of equipment utilizing instrument air, including other SOVs that perform safety-related functions.
6.3.3 Maintenance Problems - Contributions of Utility Programs and Practices Review of SOV failure reports and follow up discussions with plant personnel, NRC inspectors, and SOV manufacturers showed that shortcomings in many utilities' SOV maintenance programs and practices were a major source of SOV failures.
For example:
(1) Reference 100 indicated that Brunswick plant staff stated that ASCO Class 1E SOVs with 30 year qualified lives did not require any preventive mainte-nance for 30 years.
The licensee did not recognize the fact that the resilient, or elastomeric parts of the SOVs require more frequent replacement.
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l PRELIMINARY CASE STUDY 47 I
(2) After finding that SOVs would not shift their position-on demand during surveillance testing, it was common practice for Brunswick and North Anna Stations' plant personnel to tap the SOVs (" mechanical agitation").
If a i
SOV would change position when tested after the mechanical agitation, no further maintenance would be performed, and the SOV would be declared operable (Refs. 100,101).
(3) ASCO's valve engineering department product engineering manager visited the Susquehanna plant to assist the utility in finding the root cause of the failure of a rebuilt ASCO SOV which failed after being returned to service.
The ASCO manager's discussions with ple.at personnel revealed that subsequent to rebuilding the SOV, plant personnel bench tested the SOV with poor qual-
% service air instead of clean, dry instrument air.
Inspection of the
"'A revealed that oil from the service air system had caused the 50V's second failure.*
(4) The Calvert Cliffs 1 and 2 plants' SOV maintenance is tracked by the sta-tion's reliability centered maintenance (RCM) program.
The RCM program has found that instrument air dryer SOVs have a mean time between failure of 10 months,*but the plants' maintenance program replaces such SOVs on an annual basis.
- The failure of the instrument air dryer SOVs can cause serious instrument air system degradation leading to common-mode failures of many other SOVs, including those that perform safety-related functions, 6.3.4 Rebuilding vs. Replacement Review of SOV failure data indicates that inadequate rebuilding of S0Vs has been a significant cause of 50V failures. There is a broad range of com-plexity associated with rebuilding SOVs, depending upon individual SOV manufac-turer.and model number.
To further complicate the issue, there are variations among SOV manufacturers with regard to providing test apparatus to check the soundness of rebuilt SOVs; for example, Target Rock Corporation has marketed a test fixture for licensees to test their rebuilt SOVs.
Although -some manufacturers provide values of acceptable coil voltages, leakage rates, etc., to enable users to check the conditions of their SOVs some other manufacturers do not make such information available.
Seriousquestlons arise about the acceptability of new SOVs if acceptance criteria are not available.
In Reference 102, ASCO notified licensees that it has discontinued selling rebuild kits for its nuclear power plant SOVs (NP series).
However, ASCO is continuing to sell rebuild kits for commercial SOVs and SOVs used in BWR scram systems (purchased through GE).
As noted in Chapter 5, there have been several events in which common-mode failures resulted from incorrect rebuilding of SOVs.
The potential for common-mode SOV failure resulting from rebuilding errors may be minimized by staggering
- Telephone discussion, J. Shank, ASCO, and H. L. Ornstein, USNRC, May 11, 1989.
- Telephone discussion, J. Osborne, Baltimore Gas and Electric Co., and H. L.
Ornstein, USNRC, April 21, 1989.
PRELIMINARY CASE STUDY 48
1
- e._
the rebuilding (if possible), or by limiting the amount of SOV rebuilding done by any one individual (see Sections 5.2.2.2,5.2.2.3).
In addition to focussing attention on the useful life of SOVs being governed.
t
-by the elastomeric parts, attention should be focused on the shelf life and on the actual manufacturing date of the elastomeric parts in the rebuild kits.
For example, because of elastomeric (Buna-N) degradation observed in SOVs used in BWR scram systems, GE recommended (Ref. 56) that BWR scram system SOVs having Buna-N aarts be rebuilt periodically.
The frequency of rebuilding should be governed
)y the "useful life" of the elastomer ("useful life" being defined as the sum of shelf life and in-service life).
Controlled by the Buna-N parts, GE recom-mended a "useful life"'of seven years for scram system SOVs.
The seven years I
being from the time of, kit manufacture (not from the time of rebuild),
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1 PRELIMINARY CASE STUDY 49
1 7.0 FINDINGS The root causes of most SOV problems are traceable to the lack of
' understanding of the capabilities and requirements of SOVs.
Oftentimes plant operations = and maintenance programs do not address the short lifetimes of the resilient elastomeric piece parts of the SOVs (gaskets, seals, diaphragms, etc.).
Maintenance programs also fail to address the low tolerance SOVs have for oper-
-ating under adverse conditions that are significantly different than those of the controlled laboratory environment under which they were originally tested.
In many cates, the manufacturers have not provided the end users with a full und q u rding of the sensitive nature of certain parts of the SOVs.
Many users mat learM d after using certain SOVs that they are unforgiving and finicky with mferd to contaminants and local environmental conditions.
Deficiencies in selectfon, cperation, and maintenance of SOVs have resulted in hundreds of SOV failures, many of which were comon-mode failures that cut i
across multiple trains of safety systems.
Our major findings regarding the root causes of common-mode SOV failures are described below.
7.1 Desian Application Errors 7.1.1 Ambient Tem.peratures Many common-mode 50V failures have resulted from subjecting SOVs to ambient-temperatures in excess of their original design envelope.
Such common-mode failures have resulted from localized steam leaks (see Section 5.1.1.1),
incorrect estimates of ambient temperatures (see Sections 5.1.1.2,5.1.1.3),and failure to account for ventilation system malfunctions (Ref. 103).
Because the useful qualified-lives of the short lived parts of SOVs are halved by every 18'F temperature rise (Arrhenius theory - Refs. 104,105), seemingly minor increases in ambient temperatures above those considered in the SOV design cannot be allowedtogrevailforextendedtimeperiodswithoutrunningtheriskof sustaining seemingly" premature failures.
7.1.2 Heatup from Energization Many common-mode SOV failures have occurred because the estimated service lives did not properly include the life-shortening effects of heatup due to continuous coil energization (see Sections 5.1.2.1,5.1.2.2).
Many licensees have been unaware of this situation.
For exam certificates of compliance provided with ASCO'ple, by incorrectly using the s NP-1 nuclear qualified valves, licensees have overpredicted the service life of continuously energized SOVs.
Use of appropriate 50V heatup data in conjunction with Arrhenius theory (Refs.
104,105) has been found to be an acceptable (but not a 100 percent accurate) method for predicting SOV life.
7.1.3 Maximum Operating Pressure Differential Many licensees have found misapplications in which SOVs could be or were subjected to operating pressure differentials that could or did prevent them PRT.LIMINARY CASE STUDY 50
~
^
from operating.
Although NRC issued Information Notice 88-24 (Ref. 23) about this problem,_as noted in Section 5.1.3.1, it is not clear that all the licensees have addressed the issue, of over pressure which could result from pressure regulator f ailures.
7.1.4 Unrecognized SOVs Used as Piece-Parts-Many S0Vs used in safety-related equipment are not given prominent attention because they are used as piece-parts of larger equipment.
Specific preventa--
tive maintenance requirements are not readily available for them.
Many SOV failures have occurred as a result of the lack of maintenance or replacement of such unrecognized SOVs (see Section 6.3.2).
7.1.5 Directional SOVs Six plants have reported experiencing undesirable spurious openings of safety-related SOVs due to high backpressure.
The licensees did not recognize or were not aware of the directional requirements of the valves (see Section 5.1.4.1).
In addition to reports of SOV malfunctions which occurred because they were installed backwards there are also reports of SOVs which were installedupside-down,oratImproperangles(seeAppendixA).
7.2 Maintenance r
Operating experience has confirmed that S0V maintenance deficiencies can incapacitate multiple safety systems. The pervasiveness of maintenance defi-ciencies highlight the need for implementing aggressive 50V maintenance pro-grams to prevent widespread common mode failures.
Specific maintenance problem areas are discussed below.
7.2.1 Maintenance Frequency Lack of timely preventive maintenance (complete SOV replacement or rebuilding of short-lived piece-parts of SOVs) has resulted in many SOV f ailures (see Sec-tions 5.1.2.1,.5.2.1.2, 6.3.2.1).
Many-SOV manufacturers have failed to provide the users with definitive information on the useful lifetime of the SOVs inter-nal diaphragms, gaskets, 0-rings, coils, etc.
Some manufacturers indicate that' periodically changing the elastomeric parts is necessary, without specifying the frequency of changes.
Other manufacturers do not even mention that any changing is necessary.
Similarly, there are wide variations among manufacturers with regard to specifying (or not specifying) the allowable shelf lives of their SOVs and SOV rebuild kits (see Sections 6.3.1,6.3.3,6.3.4).
Because of the limited lives of their elastomeric or resilient parts, SOVs should be replaced or refurbished in accordance with the manufacturers' recom-mendations.
In the absence of specific manufacturers' recommendations, and in absence of applicable failure data, changeout of short-lived elastomeric and resilient materials (or complete valve replacement) should be done on the basis of material shelf life, manufacture date and installation date.
However, change-out of elasteric parts or complete 50V replacement should be done more fre-quently if operating conditions exceed the originally envisioned design conditions or if field failure experience dictates.
PRELIMINARY CASE STUDY 51
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1.
L 7.2.2 Replacement Versus Rebuilding L
Rebuilding or refurbishing certain models of several manufacturers' SOVs is L
a difficult task that can be made even more difficult if it is done in place, requiring the workers to wear decontamination or protective clothing.
- However, removal and reinsta11ation of N-stamped valves which are welded into the primary
)
system are not simple, inexpensive tasks either.
Incorrect rebuilding or refurbishing of SOVs have caused many premature failures (e.g., see Sections 5.2.2.1,5.2.2.2).
Contributing to the difficulty of rebuilding or refurbishing SOV; correctly is the fact that many manufacturers do not provide the licensees with adequate 50V documentation or testing apparatus to verify the effectiveness of the rebuilt or refurbished SOV.
As a result, post-rebuild testing at many facilities merely involves cycling verification rather than performing appropriate tests normally performed by the manufacturer during initial S0V manufacture (see Section 6.3.4).
Discussions with plant personnel have revealed that many licensees, (e.g.,
l Perry, River Bend, Salem, Grand Gulf, Duane Arnold) have chosen to discontinue rebuilding certain SOVs because improper rebuilding can result /has resulted in many S0V failures and costly down-times.
In general, licensees have reacted favorably to ASCO's recent decision to discontinue supplying rebuild kits for their NP-1 nuclear qualified S0Vs (Ref. 106, 107).
ASCO's decision to discon-
.tinue supplying SOV rebuild kits was based upon field experience which indicated that many ASCO SOV failures were caused by inadequate rebuilding techniques.
7.2.3 Contamination Many common mode SOV failures have been caused by contaminants in the fluids which flow throu h SOVs; instrument air in particular (see Sections 5.2.3.1, 5.2.3.2, 5.2.3.3.
50V contamination resulting from particulates, moisture, and hydrocarbons in the instrument air system have been a major source of common-mode SOV fail-ures.
In many plants contaminants were introduced during original construction.
Many contamination problems have resulted from poor design or maintenance of the instrument air systems.
Many SOV failures are clearly attributed to subjecting the S0Vs to conditions beyond their design regarding particulates, moisture, hydrocarbons, etc.
Contributing to the problem is the fact that some manufacturers have specified the need for clean air or instrument quality air without quantifica-tion (e.g., maximum allowable particle sizes and dew points).
Although licensees are taking actions to improve the quality of their plants' air systems, there is concern for the residual effects of previous air system contamination (Section 5.2.3.2).
Long-term SOV degradation such as deterioration of EPDM parts as a result of hydrocarbon intrusion, formation of varnish-like deposits from heatup of hydrocarbons, and residue formation from the interaction of moisture, silicone lubricant, and heat, are areas of concern.
t PRELIMINARY CASE STUDY 52
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k
'7.2.4 Lubrication Improper lubrication has resulted in many common-mode SOV failures.
The improper lubrication has been attributed to manufacturing errors (see Section 5.2.4.1), as well as licensee errors.
Errors include the wrong choice of lubricant (see Sections 5.2.4.2,5.2.4.3), unauthorized use of incorrect lubri-cant (see Section 5.2.4.1), and use of excessive amounts of lubricant (see Section 5.2.4.4).
- 7. 3 Surveillance Testing e
Several cases (see Section 6.3.3) have been reported in which S0Vs failed to actuate on demand during surveillance testing, however, subsequent tapping
(" mechanically agitating") the SOVs would enable them to actuate.
As a result, the SOVs were declared operable without addressing the cause of the original failures, thus leaving the SOVs in degraded states vulnerable to future failures upon demand.
Similarly, as noted in Section 5.3.1, incorrect surveillance testing led l
operators to operate a BWR with multiple failed scram pilot S0Vs.
7.4 Verification of the Use of Qualified SOVs The issue of environmental qualification of Class 1E electrical equipment and SOVs has been addressed by utilities in response to Bulletins79-01A and B.
Nonetheless, there are many instances in which SOVs that were assumed (in plant safety analyses) to operate to mitigate design-basis events, have been procured as." commercial grade" SOVs of questionable quality and are not being maintained in a manner commensurate with their intended safety function.
Examples have been found where commercially available, non-qualified SOVs l
are being used in safety-related applications without appropriate verification I
of product quality and design control.
In many instances the SOVs lack verifi-cation that they can withstand the accident conditions postulated in plant safety analyses.
A common problem appears to be categorization of the SOVs for use in EDG air systems.
In many cases the original equipment that contained SOVs as piece parts was certified or qualified to meet 1E requirements, whereas the individual replacement SOVs were not.
(See Section 5.4.1).
7.5 Redundancy and Diversity The root causes of many common-mode failures of safety-related SOVs have eluded many licensees' detailed failure analyses (see Section 5.2.4.4).
In many such instances the search for the origins of foreign unidentified sticky substances (FUSS) have been inconclusive, and corrective actions were limited to cleaning or replacing the failed S0Vs (e.g., Brunswick (Ref. 2), Franklin Institute (Ref. 76)).
In some cases, the licensees discounted instrument air system contamination (oil, water, dirt) as the cause of the FUSS, but plant
. operating history indicated a prior history of air system contamination which could have been a contributor to the problem.
Similarly, the 50V manufacturing process (see Section 5.2.4.1) and the licensee's rebuilding process (see Sections 5.2.2.1, 5.2.2.2, 5.2.2.3, Section 6.3.3) have been found to be the sources of contaminants which caused common-mode S0V malfunctions.
PRELIMINARY CASE STUDY 53
~
Staggering the maintenance, testing and replacement of redundant SOVs may represent a simple way of preventing common-mode failures of redundant SOVs.
In addition, if the root causes of persistent common-mode SOV failures ~cannot be found, or cannot be eliminated, the need for SOV diversity (with regard to model, energization mode, failure mode, or manufacturer) becomes a> parent.
(See-Appendix B for a discussion of an example of such a problem with tie ASCO NP8323 SOVs used for MSIV control at many BWRs.)
7.6 Feedback of Operating Experience Based upon visits to several of the major SOV manufacturers' facilities' (e.g., ASCO (June 1988), Target Rock (November 1988), Valcor (December 1988),
AVC (February 1990)) discussions with other SOV manufacturers (e.g., Circle Seal, Skinner Electric), and extensive discussions with manufacturers who's equipment utilize SOVs as piece parts. (e.g., Fisher Controls, Dresser-Rand / Terry Turbine, Xomox Valves, California Controls (Calcon), Colt /Fairbanks-Morse), it was found that SOV manufacturers have not been fully apprised by the utilities of many SOV failures that have occurred at nuclear power plants.
SOV manufacturers are not aware of many widespread failures of safety-related equipment that may have been_ caused by generic manufacturing or design deficiencies of the S0Vs.
Conversely, when licensees purchase SOVs commercially, without 10 CFR 50 Appendix B, and 10 CFR Part 21 requirements, they are not fully apprised by the manufacturers of generic defects that are discovered subsequent to delivery.
In one case, a major SOV manufacturer did not feed back generic SOV defect-information to the end user due to the manufacturer's failure to understand or properly implement the 10 CFR Part 21 requirements that were applicable to its SOVs (Ref. 74) (also see Sections 5.1.2.2,5.2.4.3).
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PRELIMINARY CASE STUDY 54 L
O
8.0 CONCLUSION
S Operating experience has demonstrated that common-mode failures and degradations of SOVs can compromise multiple trains of multiple safety systems.
The fact that hundreds, and in many cases thousands, of SOVs permeate all impor-tant systems at all U.S. LWRs highlights the necessity for eliminating comon--
mode 50V problems that jeopardize plant safety.
8.1 Safety Significance Considering the application of the " single failure criterion," the application of defense-in-depth," and the large population of SOVs used in safety-related systems at U.S. LWRs, it appears that the number of individual random SOV failures that have been reported do not appear to present a safety concern.
However, examination of the root causes of many SOV failures at'many plants demonstrate error patterns in the design / applications, maintenance and testing of SOVs which have led to a multitude of widespread common-mode failures.
Operating experience shows that SOVs are vulnerable to numerous common-mode failure mechanisms and their failures can adversely impact numerous safety sys-tems.
Some of the safety systems that were observed to be adversely impacted by common-mode failures of SOVs were:
EDG air start system, BWR scram system, BWR main steam isolation system, PWR auxiliary feedwater system, PWR safety injection system, component cooling water system, containment isolation system, residual heat removal system, containment cooling system. These safety systems are required to function in order to prevent and/or mitigate accidents and/or to protect the public from release of radiation from design basis accidents.
Therefore, we conclude that SOV problems represent a significant safety concern.
Chapter 5 presents examples of over twenty recent events having the potential for common-mode failures or degradations of over 600 SOVs in impor--
tant plant systems.* The common-mode failures and degradations cut across mul-tiple trains of safety systems as well as multiple safety systems.
The recur-rence of common-mode S0V failures or degradations highlights the gravity of the situation.
Although plant safety analyses do not address common-mode, multiple train / multiple safety system failures, operating experience indicates that they have occurred and continue to occur.
The common-mode 50V failures and degrada-tions that have occurred which compromised front line safety systems such as emergency ac power, auxiliary feedwater, high pressure coolant injection, and scram systems clearly demonstrate the safety significance of SOV problems.
Chapter 6 presents estimates of S0V failure rates which were extracted from plant operating data (NPRDS).
The estimates indicate failure rates of almost one order of magnitude larger than those assumed in the WASH 1400 study and in the NUREG 1150 methodology for level one PRAs.
Coupling such nonconservative treatment of SOV failures with the fact that level one PRAs do not address SOV failures.that cut across multiple systems leads us to conclude that the risk contribution from SOVs may have been severely underestimated in previous risk assessments.
- There have been many other similar events.
The events chosen here are intended to be illustrative.
Surely they are not a complete set of all such events, i
PRELIMINARY CASE STUDY 55
4' 8.2 Need for Action On the basis of our analysis of operating data, we conclude that the 50V problems outlined in this study need to be addressed to ensure that the margins of safety for all U.S. LWRs remain at the levels perceived during original plant licensing.
We note that to date the NRC has issued 36 generic communications pertain-ing to SOV problems (See Appendix C).
Those generic communications alerted licensees to specific SOV problems. Based on our study we believe that an inte-
. grated _ comprehensive program is neeaed now to address the root causes of SOV problems described in this report. We conclude that integrated implementation of the recommendations provided in Chapter 9 will significantly reduce the likelihood for common-mode SOV failures eroding the margins of safety at all LWRs.
PRELIMINARY CASE STUDY 56
9.0 RECOMENDATIONS In order to minimize the potential for common-mode failures, attention-should be focused upon certain aspects of SOVs. We recommend that the actions discussed below be initiated in order to assure that the plants retain the margins of safety perceived in their original licenses.
If SOVs are found to be inadequate, prompt corrective actions should be taken.
9.1 Design Verification Licensees should review SOV design specifications and actual operating j
conditions to verify that all SOVs assumed to operate in FSAR safety analyses are operating within their design service life.
9.1.1 Ambient Temperatures The reviews should assure that the lifeshortening effects of elevated-ambient temperatures are considered in the determination of SOV service life.
-9.1.2 Heatup From Energization The reviews should assure that the lifeshortening effects of heatup due to coil energization are appropriately accounted for in the determinations of j
SOV service life, 1
9.1.3 Maximum Operating Pressure Differential The reviews should assure that the potential for overpressure due to pressure regulator failure or hydraulic fluid heatup due to postulated accident conditions have been considered in the selection of the SOVs.
9.1.4 Unrecognized SOVs Used as Piece-Parts In addition to verifying the adequacy of the high visibility SOVs as noted above, similar verification should be made for unrecognized SOVs which are used as piece parts of flow regulators, governors, emergency diesel generators, etc.
9.1. 5 Directional SOVs Licensees should verify that directional SOVs are installed in orientations which will assure satisfactory operation of the safety-related equipment which l-depend upon them.
9.2 Maintenance 9.2.1 Frequency Licensees should implement 50V maintenance programs to replace or refurbish l
SOVs on timely bases.
Replacement or refurbishment schedules should focus upon y
thermal aging due to elevated ambient conditions and heatup from continuous coil l
energization.
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PRELIMINARY CASE STUDY 57
9.2.2 Replacement Versus Rebuilding
- Licensees should review their programs for rebuilding S0Vs because certain SOVs are difficult to rebuild and test properly, and improperly rebuilt SOVs degrade plant safety.
Numerous utilities canvassed have found that in most instances it is cost beneficial-to replace SOVs rather than to rebuild them.
If' licensees choose to continue to rebuild their SOVs, we recommend that they obtain or develop test equipment to enable verification that the rebuilt SOVs meet all the performance specifications of the original S0Vs.
i 9.2.3 Contamination J
SOVs, ggressive actions should be taken to assure that fluids which flow through A
instrument air in particular, are maintained free of contaminants.
If operational exp(erience indicates a pattern of S0V malfunctions resulting from contamination such as water or hydrocarbon intrusion), the affected licensees shouldconsiderreplacingSOVsthathavebeensubjectedtopreviousairsystem degradation assuming that the root causes of the air system problems have been corrected (InaccordancewithGenericLetter88-14).
9.2.4 Lubrication SOV manufacturer's lubrication instructions should be adhered to.
Sub-stitution of similar but not identical lubricants should be avoided.
- However, if substitutions are made, their compatibility with all associated hardware should be verified.
9.3 Surveillance Testing Operation and maintenance personnel training should emphasize the importance ofsurveillancetestingioningSOVs. root cause failure analysis, and timely repair or i
replacement of malfunct l
j Licensees should review, and if appropriate, modify their surveillance-
. testing procedures.
Procedures should expressly prohibit " tapping" or mechanical 1
agitation of 50Vs as techniques to assist successful operation during surveil-lance testing.
Procedures should include actions to be taken when unsatisfactory i
test results are encountered, as well as a requirement to analyze and evaluate the causes of the unsatisfactory results prior to declaring the component back in service (even though subsequent retest results may be satisfactory)..
l.
9.4 Verification of the Use of Qualified SOVs l
Licensees should review all S0Vs in safety-related applications, EDGs in l
particular, to ensure that they meet 10CFR 50 Part B and appropriate Class 1E requirements;.and that they have been installed and maintained appropriately l
to assure they will operate in a manner consistent with the assumations of the L
plants' safety analyses.
If there is doubt regarding the accepta)ility of any l
such SOVs, they should be replaced with appropriately qualified ones.
- exclusive of coil replacement - coils are generally replacement items PREl.IMINARY CASE STUDY 58 l
['
'e
- 9. 5 Redundancy and Diversity When operating experience indicates unexplained repetitive common-mode 50V failures affecting redundant components - (such as BWR MSIVs and containment isolation valves), licensees should consider aerforming maintenance, testing and replacement of redundant SOVs on a staggered 3 asis.
Additional consideration should be given to using diverse SOVs (different design or manufacturer).
9.6 Feedback of Operating Experience In order to improve SOV reliability, an industry group such as the Institute of Nuclear Power Operations (INP0) should initiate an SOV failure feedback prog-ram.
The program should alert SOV manufacturers to failures of their equi > ment-by providing them with complete failure records of their specific SOVs suc1 as those found in NPRDS.
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PRELIMINARY CASE STUDY 59
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I
10.0 REFERENCES
1.
V. P. Bacanskas, G. C. Roberts, G. J. Toman, " Aging and Service Wear of' Solenoid-Operated Valves Used in Safety Systems of Nuclear Power Plants, S
Yolume 1.
Operating Experience and Failure Identification," Oak Ridge National Laboratory, NUREG/CR-4819, ORNL/Sub83-28915/4/V1, March '1987.
2.
Carolina Power &' Light Company, Licensee Event Report (LER) 50-324/88-001 Rev. 5, Brunswick Steam Electric Plant Unit 2, February 19, 1990.
3.
Burns and Roe, " Investigation of Valve Failure Problems in LWR ~ Power 1
Plants," ALO-73, April 1980.
4.
W. H. Hubble, C. F. Miller, " Data Summaries of Licensing Event Reports of Valves at U.S. Commercial Nuclear Power Plants," January 1, 1976 to December 31, 1978, EG&G Idaho, Inc. NUREG/CR-1363 EGG-EA-5125, June 1980.
5.
"IEEE Maintenance Good Practices for Nuclear Power Plant Electrical Equip-ment; Work-In-Progress Report, Evaluation of Maintenance and Related Prac-tices for Solenoid Operated Valves In Nuclear Power Generating Stations,"
IEEE Power Engineering Society, Nuclear Power Engineering Committee, Subcommittee 3, Working Group 3.3, 1988.
6.
U.S. Nuclear Regulatory Commission, Inspection Report 50-440/87-024, Perry Nuclear Power Plant Unit 1, January 22, 1988.
7.
Cleveland Electric Illuminating Company, Licensee Event Report (LER) 50-440/87-073 Rev.1, Perry Nuclear Power Plant, Unit 1, June 3,1988.
8.
U.S. Nuclear Regulatory Commission, Information Notice No. 88-43,
" Solenoid Valve Problems," June 23, 1988.
9.
U.S. Nuclear Regulatory Commission, Inspection Report 50-440/87-027, Perry Nuclear Power Plant Unit 1, February 10, 1988.
10.
U.S. Nuclear Regulatory Commission, Inspection Report 50-302/89-09, Crystal River 3, June 7, 1989.
11.
U.S. Nuclear Regulatory Commission, Inspection Report Number 50-336/88-22, Millstone Nuclear Station, Unit 2, November 8,1988.
12.
Memorandum from J. W. Craig, U.S. Nuclear Regulatory Commission, to A. C. Thadani,
Subject:
" Status of TI 2515/98 "High Temperature Inside Containment /Drywell In BWR and PWR Plants," dated March 13, 1989.
13.
U.S. Nuclear Regulatory Commission, Information Notice No. 89-30, "High Temperature Environments At Nuclear Power Plants," March 15, 1989.
14.
U.S. Nuclear Regulatory Commission 10 CFR 50.72 Report Number 16313, Grand Gulf Unit 1, August 14, 1989.
15.
U.S. Nuclear Regulatory Commission Region II Daily Report, August 15, 1989.
PRELIMINARY CASE STUDY 60 l
l
.I 16.
System Energy Resources, Inc., Licensee Event Report (LER) 50-416/89-013, Grand Gulf 1, September ~13, 1989, 17.
General Electric Company, Service Information Letter (SIL) No.'481,
" Category 2, Malfunction of ASCO Solenoid Valves for MSIVs," February 14, 1989.
18.
U.S. Nuclear Regulatory Commission, Information Notice 89-66, "Qualifica-tion Life of Solenoid Valves," September 11, 1989, 19.
Automatic Switch Company (ASCO), dField Hotification Concerning the Qualified Life of ASCO Catalog NP-1 Valves," October 27, 1989.
20.
Memo'andum, P. T. Knutsen, Virginia Electric and Power Company, "Self Heating Effects in ASCO Solenoid _ Valves," dated February 3, 1987.
21.
Sorth Anna Power Station Deviation Report Number 87-105, dated February 4, 1987.
22.
Memorandum, P. T. Knutsen, Virginia Electric and Power Company", "ASCO SOVs To Be Replaced at North Anna Power Station Units 1 and 2, dated March 16, 1987, "23.
U.S. Nuclear Regulatory Commission, Information Notice 88-24, " Failures of Air-Operated Valves Affecting Safety-Related Systems," May 13, 1988, 24.
Wisconsin Public Service Corporation, Licensee Event Report (LER),
50-305/87-012 Rev. 1, Kewaunee Nuclear Power Plant, March 4, 1988.
25.
U.S. Nuclear Regulatory Comission 10 CFR 50.72 Report Number 12013, Calvert Cliffs 1 and 2, April 14, 1988.
26.
U.S. Nuclear Regulatory Comission 10 CFR 50.72 Report Number 12015, Calvert Cliffs 1 and 2, April 14, 1988.
27.
U.S. Nuclear Regulatory Commission, Inspection Report 50-317/88-07 and 50-318/88-08, Calvert Cliffs Nuclear Power Plant Units 1 and 2, June 3, 1988.
28.
Memorandum from S. E. Scrace, Northeast Utilities, to E. Abolafia, " Failure of Air Operated Valves'Affecting" Safety Related Systems, NRC IN 88-24, NOA 9673, CR 0488-24 Revision 0, November 8, 1988.
29.
Florida Power Corporation, Licensee Event Report (LER) 50-302/89-01 Rev.
2, Crystal River Unit 3, June 7,1989.
30.
U.S. Nuclear Regulatory Comission, Information Notice 80-40, " Excessive Nitrogen Supply Actuates Safety-Relief Valve Operation to Cause Reactor Depressurization," November 7,1980.
31.
U.S. Nuclear Regulatory Comission, Office of Inspection and Enforcement, Bulletin No. 80-25, " Operating Problems with Target Rock Safety Relief Valves at BWRs," December 19, 1980.
PRELIMINARY CASE STUDY 61
L i
~32.
Metropolitan Edison Co., Licensee Event Report (LER) 50-289/80-018. Three Mile Island Unit 1, November 4,1980..
- 33. Georgia Power Company, Licensee Event Report (LER) 50-424/87-002, Vogtle Electric Generating Plant Unit 1, February 23, 1987.
34.
U.S. Nuclear Regulatory Commission 10 CFR 50.72 Report Number 12890, Pilgrim Unit 1, July 19,1988.
35.
U.S. Nuclear Regulatory Commission Region I Daily Report, July 20, 1988.
36.
Boston Edison Company, Licensee Event Report (LER) 50-293/88-021, Pilgrim Nuclear Power Station, August 18, 1988.
37.
U.S. Nuclear Regulatory Commission, Inspection Report 50-336/88-22, Millstone Nuclear Power Station, Unit 2, November 8, 1988.
38.
U.S. Nuclear Regulatory Commission, Inspection Report 50-302/89-01, Crystal River Unit 3, April 13,1989.
39.
U.S. Nuclear Regulatory Commission 10 CFR 50.72 Report Number 14442, Crystal River Unit 3, January 7,1989.
40.
U.S. Nuclear Regulatory Commission 10 CFR 50.72 Report Number 14467, Crystal River Unit 3, January 11, 1989.
41.
Target Rock Corporation Operation Manual TRP 1571J, May 23, 1978.
42.
Gulf States Utilities Company, Licensee Event Report (LER) 50-458/89-022, River Bend 1, June 1,1989.
43.
U.S. Nuclear Regulatory Commission, Generic letter 88-14, " Instrument Air Supply System Problems Affecting Safety-Related Equipment," August 8, 1988.
44.
Gulf States Utilities Company, Licensee Event Report (LER) 50-458/89-024, River Bend 1, June 19, 1989.
45.
U.S. Nuclear Regulatory Commission, Preliminary Notification, PN0-III-85-84, L
September 20, 1985.
46.
U.S. Nuclear Regulatory Commission, Region III Daily Report, September 24,
'1985.
47.
Commonwealth Edison Company, Licensee Event Report (LER) 50-249/85-018, 1
Dresden Nuclear Power Station, Unit 3, October 1,1985.
l L
48.
U.S. Nuclear Regulatory Commission, Office of Inspection and Enforcement, Information Notice No. 85-95, " Leak of Reactor Water to Reactor Building l
Caused by Scram Solenoid Valve Problem," December 23, 1985.
49.
U.S. Nuclear Regulatory Commission, Office for Analysis and Evaluation of Operational Data, Case Study No. AEOD/C403, "Edwin I. Hatch Unit No. 2 Plant Systems Interaction Event on August 25, 1982," May 1984.
1 PRELIMINARY CASE STUDY 62 1'
1
1
,,i.
I
- 50.
Carolina Power & Light Company, Licensee Event Report (LER) 50-325/79-074, Brunswick Steam Electric Plant, Unit 1, November 16, 1979.
51.
U.S. Nuclear Regulatory Commission, Office of Inspection and Enforcement Bulletin No. 80-14, " Degradation of BWR Scram Discharge Volume Capability,"
June 12, 1980.
Sla. Cleveland Illuminating Company, Licensee Event Report (LER) 50-440/87-009, Perry Nuclear Power Plant, March 27, 1987, 52.
Carolina Power & Light Company, Licensee Event Report (LER) 50-325/87-020, Rev.1, Brunswick Steam Electric Plant Unit 1, March 31,1988.
53.
U.S. Nuclear Regulatory Commission, Information Notice 87-48, "Information-Concerning-the Use of Anaerobic Adhesive / Sealants," October 9, 1987.
54.
Philadelphia Electric Company, Licensee Event Report (LER) 50-278/83-018, Peach Bottom 3, February 10, 1984.
55.
U.S. Nuclear Regulatory Commission, Office of Inspection and Enforcement, Information Notice No. 84-53, "Information Concerning the Use of Loctite 242 and Other Anaerobic Adhesive / Sealants," July 5,1984.
56.
General Electric Service Information Letter (SIL) No. 128, Revision 1, Supplement 1, Category 1,." Preventive Maintenance for CRD Scram Pilot Valves," August 1978.
57.
General Electric Service Information Letter (SIL) No. 128, Revision 1, Supplement 1, Revision 2, Category 1, " Preventive Maintenance for CRD Scram. Pilot-Valves," dated March 2, 1984.
58.
Letter from P. W. Howe, Carolina Power & Light Co., to J. N. Grace, U.S.
Nuclear Regulatory Commission,
Subject:
Docket Nos. 50-325 and 50-324 Brunswick Steam Electric Plant, Units 1 and 2, " Failure of ASCO 8323 A36E Double Solenoid Valves," October 15, 1985.
59.
Carolina Power & Light Company, Licensee Event Report (LER) 50-324/85-008, Brunswick Unit 2, October 25, 1985.
- 60. ' U.S. Nuclear Regulatory Commission, " Report to Congress on Abnormal Occurrences, October-December 1985," NUREG-0090, Vol. 8, No. 4, May 1986.
61.
North Anna Station Deviation Report,87-379, April 24, 1987.
62.
U.S. Nuclear Regulatory Commission, Inspection Report 50-338/88-02,
~50-339/88-02, North Anna Power Station Units 1 and 2, March 14, 1988.
63.
Virginia Electric Power Company, Licensee Event Report (LER) 50-338/89-002, North Anna Unit 1, February 7, 1989.
64.
North Anna Power Station, memorandum, " Water Intrusion Into Instrument Air System Event - April 1987," by T. L. Porter, August 8,1988.
PRELIMINARY CASE STUDY 63
g-65.. North Anna Power Station, memorandum, " Justification for Continued Opera-tion, Unit 2 for ASCO CCW Trip Valves," by M. L. Bowling, February 10, 1988.
- 66. - North Anna Power Station, memorandum, " Justification for Continued Opera-tion, Rev.1," by D. A. Heacock, February 9,1988.
67.
U.S. Nuclear Regulatory Comission, Region II, " Notice of Significant Meeting," February 2,1989.
68.
U.S. Nuclear Regulatory Comission, Inspection Report No. 50-387/84-35; i
50-388/84-44, Susquehanna Steam Electric Station, November 15, 1984.
3 69.
U.S. Nuclear Regulatory Commission, Inspection Report No. 50-387/85-09, 50-388/85-09, Susquehanna Steam Electric Station, April 15, 1985.
70.
U.S. Nuclear Regulatory Commission, " Report to Congress on Abnormal Occurrences, October-December 1984," NUREG-0090, Vol. 7 No. 4, May 1985.
71.
U.S. Nuclear Regulatory Commission, Inspection Report No. 50-387/84-38, 50-388/84-37, Susquehanna Steam Electric Station, February 27, 1985.
- 72. Wisconsin Public Service Corporation, Licensee Event Report (LER) 50-305/
88-07, Rev. 1, Kewaunee Nuclear Power Plant, May 19, 1989.
73.
Letter from J. P. Weaver, Automatic Switch Co. (ASCO) to T. E. Murley, U.S. Nuclear Regulatory Commission, " Potential Failures of NP8314 Series Valves," October 18, 1988.
74.
U.S. Nuclear Regulatory Comission, Inspection Report 99900369/88-01, Automatic Switch Company, August 30, 1988.
L 75.
Omaha Public Power District, Licensee Event Report (LER) 50-285/82-006, Fort Calhoun Station Unit 1, April 7, 1982.
76.
V. P. Bacanskas, G. J. Toman, S. P. Carfagno, " Aging and Qualification Research on Solenoid Operated Valves," Franklin Research Center, NUREG/CR-5141, August 1988.
77.
General Electric Service Information Letter (SIL) No. 196, Supplement 10, Category 1, "SRV Failures To Open On Manual Demand and Air Operator Seal Failures," dated April 1981.
78.
Duke Power Company, Licensee Event Report (LER) 50-414/87-031, Catawba Nuclear Station, Unit 2, January 20, 1988.
79..
U.S. Nuclear Regulatory Commission, Inspection Report 50-413/88-20 and 50-414/88-20, Catawba Nuclear Station Units 1 and 2, June 7, 1988.
L 80.
U.S. Nuclear Regulatory Commission, Inspection Report 50-413/89-07 and F
50-414/89-07, Catawba Nuclear Station Units 1 and 2, April 20, 1989.
81.
Letter from T. Hutchins Automatic Valve Corporation (AVC) to J. Keppler, l
U.S. Nuclear Regulatory Comission Region III, December 19, 1986.
l.
PRELIMINARY CASE STUDY 64 i
82.
Mississippi Power & Light Company, Licensee Event Report (LER) 50-416/85-007 Rev. 2, Grand Gulf Nuclear Station, Unit 1, October 2,1985.
1 83.
U.S. Nuclear Regulatory Commission, Information Notice No. 85-17, Supplement 1, "Possible Sticking of ASCO Solenoid Valves," October 1, 1985.
84.
Commonwealth Edison Company, LaSalle County Station, "30 Day Report on the Failure of Main Steam Isolation Valve (MSIV) Pilot Solenoid Valve 1B21-F028C " prepared by Sargent & Lundy, January 14, 1988.
85.
U.S. Nuclear Regulatory Comission, Inspection Report 50-373/87-035, LaSalle County Station, Unit 1, January 1988.
- 86. Gulf States Utilities Company, Licensee Event Report (LER) 50-458/88-023, River Bend Station, Unit 1, October 31, 1988.
87.
U.S. Nuclear Regulatory Commission 10 CFR 50.72 Report Number 13591, September 30, 1988.
l 88.
Gulf States Utilities Co., River Bend Station, " Analysis of Components in an ASCO Solenoid Valve," Franklin Research Center Report, P-741-1, February 9, 1989.
89.
U.S. Nuclear Regulatory Commission 10 CFR 50.72 Report Number 17201, November 27, 1989.
90.
U.S. Nuclear Regulatory Commission Region III Daily Report, December 4, 1989.
91.
Cleveland Illuminating Company, Licensee Event Report (LER) 50-440/89-030, Perry Nuclear Power Plant, December 26, 1989.
92.
Automatic = Switch Co. (ASCO), Installation and Maintenance Instructions, Bulletin 8323, Form No. V5972R1, 1981.
93.
U.S. Nuclear Regulatory Commission, Inspection Report 50-289/88-28 Three Mile Island Nuclear Station Unit 1, February 2, 1989.
94.
Facsimile Transmission, J. Shank, ASCO, to H. L. Ornstein, USNRC, February 17, 1989.
95.
U.S. Nuclear Regulatory Commission, Region I Daily Report, December 9, 1988.
96.
Rochester Gas & Electric Company - Ginna Station Memorandum, " Failure of Solenoid Operated Valve 5933B "A" Diesel Generator Air Start Valve ASV-1" by B. Popp, December 14, 1988.
97.
U.S. Nuclear Regulatory Commission, Inspection Report 50-244/88-25, Ginna Nuclear Plant, February 2, 1989.
98.
Iowa Electric Light and Power Company, Licensee Event Report (LER) 50-331/
82-G39, Duane Arnold Energy Center, July 6, 1982.
PRELIMINARY CASE STUDY 65
)
- 99. Iowa Electric Light-and Power Company, Licensee Event Report (LER) 50-331/
85-002, Duane Arnold Energy Center, February 27, 1985.
100. U.S. Nuclear Regulatory Commission, Inspection Report, 50-325/88-25 and 50-324/88-25, Brunswick 1 and 2, September 26, 1988.
101. U.S. Nuclear Regulatory Commission, Inspection Report, 50-338/88-02 and 50-339/88-02, North Anna 1 and 2, March 14, 1988.
102. Automatic Switch Co. (ASCO) Service Bulletin, " Discontinuation of Rebuild Kits for ASCO "NP" Series Valves," May 23, 1989.
103. Commonwealth Edison Company, Licensee Event Report (LER) 50-237/88-022, Dresden Nuclear Power Station, Unit 2, December 13, 1988.
104. D. V. Paulson, T. A. Shock V. P. Bacanskas, S. Carfagno, " Equipment Qual-ification Research Test Program and Failure Analysis of Class 1E Solenoid Valves," Franklin Research Center, NUREG/CR-3424, F-C 5569-309/315, November 1983.
105. S. P. Carfagno, R. J. Gibson, "A Review of Equipment Aging Theory and Technology," Franklin Research Center, EPRI NP-1558, September 1980.
106. Automatic Switch Company (ASCO), " Field Notification of Discontinuation of NP8323 Valve Line," August 3,1989.
107. Automatic Switch Company (ASCO), " Revised Field Notification of the Discontinuation of NP8323 Valve Line," October 27, 1989.
l l
I l
PRELIMINARY CASE STUDY 66
u
- 9 4
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APPENDIX A SOV FAILURES REPORTED IN LERs:
1984-1989 L
i
+
4 4
. ~.
l legend for. Appendix A 000 NO. = Docket Number REP FL = Repetitive Failure TP/0VT = Cause Reactor Trip or Plant Outage FC.
= Failure Category
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APPENDIX C GENERIC COMUNICATIONS ON SOVs i
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- - - - - ~
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l APPENDIX B Disposition of ASCO Dual-Coil 8323 SOVs Used for MSIV Control Many plants have experienced problems with ASCO dual-coil 8323 SOVs which have been used for MSIV control.
Several examples are provided in Chapter 5.
ASCO issued two field notifications (Refs. 106,107) addressing NP8323 SOVs.
The notifications. stated that the NP8323 S0Vs have no defects, and that their mal-functions were primarily caused by foreign materials, aggrevated by adverse service conditions.
Furthermore, because ASCO does not envision significant changes in the service conditions that the NP8323 SOVs are subjected to, ASCO is phasing out the sale of those valves.
As an alternative, ASCO recommends 1
the use of.a pair of single-coil NP8320 SOVs.
Two NP8320 SOVs can be configured to perform the function of one NP8323.
Because of the NP8320 SOV's single-coil construction, ASCO anticipates that they will perform more satisfactorily than i
the NP8323 SOVs under adverse service conditions.
In anticipation of ASCO's discontinuance of the NP8323 SOVs, the MSIV air pack manufacturer (R. A. Hiller Company) has initiated a program to select a suitable replacement of the ASCO NP8323 SOVs.* The Hiller company has assembled five MSIV j
air packs for baseline testing.
The SOVs to be tested in the MSIV air packs are:
i ASCO:
HP8320 V (2 valves configured as recommended by ASCO in Refs.
l 102,103).
AVC:04964 i
Target Rock:
f SMS - S02 (modified)
Valcor: V70900-87V Zeiss: 629-60007 (assembly)
GE and Hiller Company have noted that all of the American SOVs are 1E qualified; and that although the Zeiss assembly is not 1E qualified, it has been used successfully in Europe.
It should be noted that the choice of a replacement for the NP8323 SOVs can affect L
'the qualification of the_overall MSIV air packs (e.g. seismic / dynamic loading).
Final selection of replacements for the NP8323'S0V should address this issue.
In the past, GE was actively involved in the qualification testing of MSIV air packs which were used at many plants.
GE has indicated that as a result of ASCO's discontinuance of NP8323 S0Vs they are trying to interest BWR owners to support a consolidated effort with the Hiller Company to qualify MSIV air packs having suitable replacements for the ASCO NP8323.**
1 l
- Telephone discussion between J. Nanci, R. A. Hiller Company, and H. L.
Ornstein, USNRC, December 8, 1989.
- Telephone discussion between C. Nieh, GE, and H. L.
Ornstein, USNRC, December 1989.
l PRELIMINARY CASE STUDY B-1
-eg;;
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a 1
APPENDIX B DISPOSITION OF ASCO DUAL-COIL 8323 SOVs USED FOR MSIV CONTROL L
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35 06/07/90 SOLEN 0ID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED STSTEM MANUFACT MODEL ROOT REP CORRECTIVE ColeENTS REFERENCE' TP/ FC '
NO.
NAME-DATE NUMBER FAILURES FART NO.
CAUSE FL. ACTION DOCUMENTS OUT '
453 River Bend 05/02/89 89-022 Affected Target 77kk-01 Sackwards Yes SOVs See section" LER 89-024 No. 14 ~
many Rock 3
instattation reinstetted in 5.1.4.1 for
. systems.
due to reverse:
'additionet See consnent inadequate orientation details instattation instructions 458 River Bend 04/06/89 89-024 0
Affected Target 77KK-01 sackwards Yes Reversed Potentist LER 89-022 No 08 many Rock 3
instattation -
orientation of conanon-mode systems.
design error.
SOVs failures. 6 See consnent inadequate SOVs had the instattation same instructions.
Instaltation defIclency.
See section 5.1.4.1 of this report for info 461 Clinton 03/06/87 87-009
~ One SOV Fuet Not Not' Not Specified No Replaced SOV None None No 03' f ailed in Building Specified Speclif mid Ventilation ed position 461 Clinton 04/14/89 89-019 Electrica Main steam.Seitz Design error Instatt heet Failed to meet No 08 L
(MSIV)-
(EQ).
shrink ttbing E0 instattation connectio Inedequate per EO requirements ns electrical requirenents connector seating i
461 Clinton 11/29/89 89-037 one 0-rings Vacuut GPE LD240-4 Inedequate No Refurbished No scheduled No 03 relief Controts 20 preventive SOV, replaced preventive (SOV (GPE) maintenance 0-rings maintenance unspecift program.
i ed)
Failure discovered during stroke l
testing
(.
483 Cattaway 01/02/85 85-001 One Not Feedwater Not Not Licensee Yes Replaced SOV SOV is a None Yes 00 l
Specified Specified Specifi considered piece-part of' ed this to be a FWIV hydraulic random failure operator l
ih Page No.. ' 36 06/07/90
- 50LEN0!D-OPERATED VALVE FAILURE DATA DOC PLANT EVENT
'LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE :
Cosg4ENTS REFERENCE /TP/FC.
-NO.
NAME DATE NUMBER FAILURES-PART NO.
. CAUSE FL ACTION DOCUNENTS OUT.
483 Catlaway 02/20/86 86-002-01 None.
Electrica Reactor head Not Not Construction Yes Not Specified 'on 2 occasions None No 28 '.
I vent and specified speciff and startup Licensee found it had not ~
connector chemical ed program
' instatted s
voltsne deficiencies control environmentatty qualified.
connectors on 50Vs as required (3..
Sovs) 528 Palo Verde 1 08/08/85 85-052 Two or more potential Post Airantic Not Design error No Affected SOWS Sovs control None -
No 14 incipients insulatio accident Specifi were shielded air-operated '
n sampling ed to reduce post sample flow breakdown accident controt valves-
/ shorts radiation to ground i
i
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Page No.
33 06/07/90 SOLENotD-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER-NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTtvE CopWENTS REFERENCE TP/ FC WO.
NAME DATE NUMBER FAILURES PART NO.
' CAUSE FL ACTION DOCUMENTS OUT 423 Mittstore 3 03/07/87 87-008 One Colt Feedwater Skinner V5H6620 Cause for open Yes Replaced SOV SOV was ~
LER 86-051 Yes 00 0
eircuit not operating (open within its specified icircuit)-
" design life" 423 Mittstone 3 05/06/87 87-024 One SOV would Emergency Circle N2990-9 Not specified No Failed air Failed SOV None-No 20 not shift dieset Seat 617 start SOV and resulted in the dieset's slow (out of within generator redundant SOV spec) EDG spec air start were replaced starting time with new ones 423 Mittstone 3 09/23/87 87-034 One Colt Feedwater Skinner V5H6620 Root cause of Yes Replaced SOV.SOV controts. LER Yes 01.
Electric 0 colt failure hydraulic oit-87-08/86-0 flow to FW1V 51 (open circuit) not determined.
Coit was within its
" qualified life" 424 Vogtte 1 01/22/87 87-002 Eight incipients Potentist Main Steam Keane Not Design error No instatted a Potentist for None.
No 13 for MOPD specift relief valve cessen-mode ed on each MOPD failures hydraulic due to bestup system to of hydraulic timit pressure fluid. See to betou MOPD Ser. tion 5.1.3 timits of this report.
424 Vogtte 1 04/24/88 88-013 One Colt Feedwater Skinner v5H6559 Colt burmut No Replaced SOV SOV is a None No of and similar piece-part of Electric 0 SOV on other A0V controltIng train of FW1V FWiv control system 440 Perry 06/30/86 86-030 One Seat Containment ASCO 8320 Dust from No Replaced SOV None None No.12 teskoge vesset and instrtsment air DrywetI prevented Purge proper valve seating
Pag 6 No.
34 06/07/90 SOLEN 0ID-OPERATED VALVE FAILIJRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE CopWIENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER FAILtJRES PART NO.
CAUSE FL ACTION DOCt94ENTS OUT 440 Perry 02/27/87 87-009 Two Air Emergency Nemphrey TOG 2E1-Failure due to Yes Reptoced Seth Simultaneous None No 17 teskoge Diesel Products 3-10-35 entended SOWS.
casamon-mode (through Generator service with Returned failure of both etastomer control Air high tocet f ailed SOVs to diesets. Delay ic parts) tegeratures EDG in repairing and continuous s'enufacturer tesking SOYS energiration.
for anstysis. contributed.
SOVs in sve 10 Will w orade See Section years and preventive this report never had PM maintenance and elastomers 440 Perry 10/29/87 87-073-01 five SOVs on two Elastomer Main steam ASCO NP8323 Nest and '
Yes Replaced or Cosmon-mode -
Insp Rpt Yes 10 occasions ic seats, (MSIV) seisture from refurbished failures. See 87-024
- discs, steam teaks SOVs Section 5.1.1.1' etc of this report for additional information 440 Perry 03/10/88 88-010 One Core Auxitlary ASCO 8320 Inadequate No Replaced SOV. Failure of SOV None
- No 17 shaft Building (no)'
Instituted a results in loss wear ventitation preventive preventive of RWCU room maintenance maintenance cooling for this SOV program (replace when upgrade to fait). Vstve replace those had been in SOVs every 2 service for years l
over 5 years 440 Perry 02/03/89 89-004 One Auxiliary ASCO 8320 Yes Reptoced SOV Licensee LER 88-010 No 19 bul(ding investigating ventitation root :ause 456 Braidwood 1 09/15/89 89-010 One Colt containment Valcor v526-53 Colt leads No Replaced with Also replaced 5 No 09 Isolation 95-1 tabeled different other simitar (hydrogen backwards modet SOV SOWS. Licensee anatyrer) investigating i
source of i,
mistabeling l
(manufacturer vs. plant) e 8
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Page so.
31 06/07/90 SOLEWO!D-OPERATED WALVE FAILUDE DATA DOC PLANT EVENT LER
- 0. OF FAILED SYSTEM 8NINUFACT MMPEL N007 REP CORWECTIVE Cop 51EWTS WEFEaEWCE TP/ FC 800 PESTS Wyt WO.
NAME DATE NUMBER FAltuRES PART so.
CAUSE FL ACTitBI 409 Le Crosse 07/C8/86 86-020 One Colt Control Rod soyet not Urtertain, tes Septoced SOW There have been LER 85-88 Yes #1 7 previous Orive Indtstrie Specif f unter s
ed intrusion or eersus due to rendse coil the scram solenoid faiture suspected shorting out.
409 ta Crosse 07/19/86 86-024 One Electrica peector ASCO 8300 Persomet no Repisced Sot ESTAS Wone so ff actuotion, I short cavity error-cascading event j
ventitetion spieshed meter l
en Scv 409 to Crosse 12/09/S6 86-036-01 One Colt Controt mod toyet mot tireertain, ves e ntecad There Iw tm LER ves 18 Driva Industrie Specifi egeing er sewerst Sors. 8 previous 85-06,86-0 s
ed weisture Reptocement of screms de to 20 l
intrusion SOWS will be these StW suspacted included in failures. 50y CRDM that failed wes pre _ 4.we about 20 years
.eintenance old.
progreur 410 Nine Mile Pt 2 06/22/88 88-025 Nunerous Mydraulic Feedwater tearwr 33896 Foreign objer,t so Replaced 30W, S0W is None Yes 93 in Sov, due to etso reptoced place-port of internet ports Controt annufacturing simiter 50Vs levet control Unit deficiency or in other vetwe felture to trains because instatt fitter of serious degradstion of screen their internets 50V Reconnected SOU felture 50 98 414 Cateube 2 10/11/86 86-045 One Failed to AFU (steen shift erAsission to incorrectly SOV property defeeted amnet instetted per stort turbine) capability of on inencrect AFU turbine desie drawing" 416 Cranri Cutf 1 02/10/85 85-097-02 Three core-plus Main Steaur ASco 8323 tus$
so acptoced ett 8 See section sene Yes 65 MSIV S0Ws 5.2.4.4 nut (Mstv) sticking y.
~,
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~
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[. "
- ' ' ~' ' ' ' '
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7
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Page No.
32 06/07/90 SOLEuotD-OPERATED VALVE FAILtJRE DATA DOC PLANT EVENT LER N0. OF FAILED SYSTEM RWIUFACT MODEL ROOT REP CORRECTIVE CGUIENTS REFERESCE TP/ FC No. #AME DATE WUMBER FAILURES PART a0.
CAUSE FL ACTION 00 M WTS tRfT 416 Grand Gulf 1 09/25/85 85-038-01 One Colt Drywell ASCO A320 Enessive no Folied Set ticenese steted serie me 11 equipemt corresten reptoced with thet the SUV drain witivin the e delicate did not need to coit housing be tetleve J te be enviro w etty caused ty seated weter W eh enteted dtfring plant construction 416 Grand Gulf 1 07/30/86 86-026-01 cne Celt control Red ASC3 1050632 Particutete no Reptoced SOV, Porticutete sone so 12 Drive SP1 occtsest atien system filters occteestetten on the volve to be checked resulted in en seating and sampted inovertent surface for control red perticutetes withdrouet 416 Grand Gulf 1 01/08/87 87-001 One Sov offges ASCO 8320 mot spwified no not specified feedified system mone me 00 feited in sempting
- specific mid-posit actions taken ion regarding SOV not stated 416 Grand Cutf 1 03/15/88 88-010 One Loose Contret Rod ASCO Wot Cause of loose No The too9e LiceMee to None Yes 07 terminal specifi comection not terwinst evetuste desiyt tmx ed foted comectim was change to connectio eteened &
leprove n to Sovs tightened.
retlebility of Other 30t power teeds terminet connections checked, ett were okey 423 Mittstone 3 09/06/86 86-051 mot specified
- Feited Feedweter Not Not Intermittent so Att locet Wone hone Yes 01 electrice Spacified speciff open circuit, terminotions Ity" ed ecet cause en the 30t
- cnkneen, wiring to be suspect checked for viteetion and tightness steem during the ineirupment next shutdown.
from a pecking teek O
e S
e
,w,-
e Page No.
29 06/07/90 SOLEWotD-OPERATED VALVE FAILtmE DATA DOC PLAaT EVENT LER No. OF FAILED SYSTEM K NUFACT MODEL ROOT REP CORRECTIVE (DWIENTS BEFEaEeE TP/ FC NO.
NAME DATE NUnisER F AILt*ES PART NO.
CAUSE FL ACTION DOCUMEWTS SH-338 Suscpabame 2 02/27/89 89-003 One conteirament ASCO Yes seplaced 904 Licenece shut LER M-036 to 21 isoleiion doun plant (recirculati instead of on pump contirasing chitled operation et water reduced pouer per tech specs 389 St. Lucie 2 08/16/89 89-006 One not nydrogm Vatcor 52600-5 wet spacified no aeptoced Sov mo 21 specified se, ting 15 395 Simoner 06/29/86 86-011 One Electric Feedwster Not not Oxidstion of No Electricet mone mene Yes 07 connector (FWIW)
Specified Specifi connactor pins connector and ed 50W were reptoced.
395 Sime=*r 12/02/88 88-012-01 wone many Ground Main Steam ASCO mot Design wo Isoteted S0W Found that None No 14 incipients feutts and Specifi deficiency contacts to gromd faults feedwater ed prevent could cause spurious sgmirious 50W octuations actuations 395 Sunner 02/17/89 89-003-01 None, 3 Electrice Main steam Incerrectly no modified comonon-mode LER 88-012 No 07 incipients 1
(MSIV) desigred wiring feiture grounding isolation potentist for retey ett 3 MSIVs 397 v4P 2 03/22/84 84-027-02 Fifteen Cromd Main steam not mot Set Yes Raptoced Events et WP LER to 14 feutts (M5ev)
Specified Specifi susceptibility defective occurred during 84-027-01 ed to spurious Sows. Tested startup ectuation dJe potentietty testing.
to ground effected 30Ws. Common-mode foutts Vettsee spike feiture suppression potentiet.
diodes were Previous instetted on simiter events ett MSev+ ADS et Le Setle +
S0Ws Susquehenne 397 WP2 07/23/85 85-050 Two feitures (1 O!aphre9e Fire not not aoot cruse of so 1-R*ptseed mone mane we 08 SOV)
/seet protection Spacified Specifi diaphrsgo diaphreestrwety teskoge ed teekoge not e seet.
2-specified.
backwords Bockwerds bonnet bonnet due to
- repaired" inadequate meintenance m
.m
Page No.
30 -
06/C7/90 SOLEWOID-CPERATED VALVE FAILtRE DATA DOC PLAWT EVENT LER NO. OF FAILED SYSTEM MANUFACT NODEL NOOT WEP CURRECTIVE CtpelENTS WEFEeEWCE TP/ FC NO.
NAME DATC uuMBER FAllt*ES PART NO.
CAUSE FL ACTION DOCUMEWTS Mff 400 Shearen Merris 1 02/08/88 88-006 Two Failed to Emergency Target 790-024 Source of Yes Time feited ComaarHusde mene se 12 close service Rock debris Sovs were feiture water ptsup occtsmist ation repelred. #o effecting both seat water not specified statement made trains of st w ty about actiers Energency taken for service teater removel of detris or prevention of additionet debris 400 Shearon narris 1 05/13/88 88-012 Two Failed to Emergency Terget 790-024 Debris in Yes sepelred S0Ws 14 shift service Rock water and blocked water seat off source of water supply debris 400 Shearon Harris 1 09/09/88 88-026 Eleven or more Internet Contairment Target Eleven Manufacturing so UntpJetified C-. A mene no 06
/ reed isolation Rock models deficiency ports of TE failure switch (ms vr harsh erw.
potentist for wiring systems)
Sovs reptoced 1E Sovs for with quotified hersh ones.
envirorummts.
Corrective S0Ws for action for ex-conteirummt non-borah env. etso deficient.
Sovs not specified.
409 La Crosse 12/03/84 84-022 One Seet Isoletion ASCO 8210 mot Specified Yes septaced 50t Kone mene no 03 leekage Condmser 409 La Crosse 04/20/85 85-006 One Colt Controt Rod Royet not mot Specified Yes Reptoced S0W None LER 81-13 YES 01 Drive trdJstric Speciff s
ed 409 Le Crosse 05/17/85 85-012 One seet contret med moyet mot acot cause of Yes septaced Soy wene mene Yes 12 Drive IrvAJstrie specif f metet chip in s
ed SOW seet not specified O
y
., -. ~ -
.m e
Page No.
27 06/07/90 SOLENOID-OPERATED WALVE FAILURE DATA DOC PLANT EVENT LER WO. OF FAILED SYSTEM 8tuRT4CT HODEL WOOT REF CORRECTIVE Ctp51ENTS WEFEWERE TP/ FC NO.
WAME DATE NUMBER FAILURES PART a
No.
CAUSE FL ACTICN DottpENTS aff 3 73 Lesette 1 02/02/85 85-005 Four Diephrege Weector ASCO 8316 Diaphropio Yes metstritt 90ws, will change ao 93 s
building lost their cycling S0Ws to nutteer wentitetion resitlence fregsency to quetifled be inereesed uP8316 modet 3 73 LaSette 1 03/12/87 87-013 Six incipients not mein Stema not not nigh dryvett no Anotyre Three Sovs mene so 10 Specified (MSRV)
Specified Specifi tesiperature effects of dectored ed high dryvett inoperable.
temperature three S0Ws suspact due to high local temperatures 374 LaSatte 2 06/05/84 84-033 One plus sunny Passegaws Conteirwient ASCO 206-832 50v wes peposittened other simitecty no 05 incipients y blocked isolation improperty SOY affected Sovs were positioned reposittened or reptoced 3 74 LaSatte 2 11/20/84 84-076 One Coit Turbine not mot Anction box no Replaced Sov mone none so 11 Stess 8ypass Specified Spaciff was futt of ed water of as*nown origin 3 74 LaSette 2 07/31/86 86-013
- ene - Many-Electrice (20, RCS ASCO See Design error Yes Repelred att 1E egaipment LER 86-012 so 28 incipients t
- recire, cepenant affected used electriest angsstified connectio RefC, s
terminations electrical ns service to meet cerviectlens, wetw, fteor quotification Sov modet nos.
drain, air regst rements uva-206, NP206, WP-8320, NP-8323
(
3 74 LaSatte 2 01/17/87 37-002 One Leekage Feeduster vetcor V52660- Root cause of Yes nefurbished 50v body and eksne no 12 3292-16 cerrosion, Sov stem corroded,
[
dirt and 50v fitted with e-ring dirt, and def onnet ton e-ring was ret stated deforined I
b
a Page No.
28 06/07/90 SOLEWOID*0PERATED VALVE FAILURE DATA DOC PLANT EVENT LER WO. OF FAILED SYSTEst MauuFACT MODEL ROOT REP CtRRECTIVE CseENTS REFERENCE TP/ FC i
NO.
NAME DAIE NUMBER FAILURES PART NO.
CAUSE FL ACTION 000NEEWTS SUT 382 Waterford 12/11/87 87-028 One 50v Mein Steen Fluid 7WMP477 Not specified so Reptoced Sov Sov felled mene Yes 05
- stuck (MSIV)
Controt 4-600K8 during testtrg.
epen*
Inc.
65 LER noted previous terelated S0v felture due to open colI.
387 Susquehanne 1 02/25/84 84-010 One 50v Main steem not mot not Specified so Reptoced Sov SOV stuck epen mene Yes 05
- stuck (MSRW)
Specified Specifi causing SRV to open" ed remain open 387 Sesquehanno 1 06/13/84 84-044 Severet
- Discs, Control Rod ASCO RV-176-Contamination Yes Refurbished See Section pone no 12 repetetive seats ortve 816 of the air Sevs, upgraded 5.2.3.3 of this fattures system and disc meteriet report elevated from tenverstures polyurethene to Viton 387 Susquehanno 1 07/06/87 87-023 One Coit Conteiruent Cirete mot asurned epen* Yes Reptoced colt opm coit found mone so 01 Vacuum Seet Sp nifI coit on some vacutse Relief Controts ed breaker in 10/82. A unit 2 vacutse breaker etso had a simiter Circle Seet 50v colt failure in 4/87 387 Susquehanne 1 02/04/89 89-006 Three
- mechanic m pression circle Root cause Yes Reptoced one 50v felled, LER 87-023 Yes 19 a
etty chamber Seet onetysis feited Sov and homever two bound" dryvett ptemed but eight simiter simiter Sovs vacutse not complete enes had "probtems" breaker yet
(* problems
- not speciffed) 388 Susquehanne 2 01/10/87 87-001 Two Not Reactor Asco not mot Specified no Reptoced 50v sone some Yes 02 Spectfled 3uiIding specifI Chitted ed Water 4
4 e
9
Page no.
25 06/07/90 SOLEm0!D-CPERATED VALVE FAILtJRE DATA DOC PLAmi EVENT LER m0. OF FAILED STSTEM MmmuFACT 8800EL 2007 REP CORRECT!wE COMMEmTS REFEREmCE TP/ FC m0. NAME DATE mUMBER TAILURES PART m0.
CAUSE FL ACTION 900JMEmTS SWT 366 Match 2 09/21/84 84-021 One Gasket Mein Steen ASCD mot mot Specified no acptoced mene mene Yes 93 (Msiv)
Speciff gesket ed 366 Match 2 01/20/88 88-006 mumerous Leskege conteirament Target 75F-009 Inedegaste no Reverse See section LER me 08 isolation Rock
/7567F instructions /
orientation of 5.1.4 of this 366/96-020 normet use and sueny S0Ws/
report (sunny systems) weer reptoce failed e-rings 366 notch 2 02/12/88 88-007 Twelve not Conteirwent Target 73C-001 Inse g;ete no Reversed See section mone no 08 Specified Isoletion - Rock
/75F-00 instructions /
orientetion/fo 5.1.4 of this Torus 9
design r unit ene report Drywett deficiency instet ted stronger vacuus springs Breaker 368 Ano 2 04/26/87 87-003 Two Seat Reactor mot mot Seet teekege no Reptoced Sov Concern for mone no 03 leakage Cootent Specified Sp miff and instetted teek causing (pressurizer ed a cettector corrosion for any future demoge to other high point Ieekege components verat) 368 Ano 2 04/29/85 88-001 2
Leekage Conteirwent forget 80E-001 sockwards Reinstetted See section so 08 isolation Rock instattation 50Vs in 5.1.4 of this de to reversed report for (poss) inadequete orientation additConet info instettetion instructions 368 ano 2 02/16/89 89-003 0
Conteirwent Target 74F Desiy, error-Refurbished vetwe bed to 14 isolation Rock incorrect Sov. Checked enceeded ES (hydrogen essessment of others for life 6 years onetyzer SOF stariter & sign prior to sesuding) life-feiture error discovery of to account probteur for heetue d e to energization 369 McGuire 1 07/23/84 84-023 One Seat seein Bors not nydraulic me Adjusted Soy mene mene Yes 03 deformati Feedweter Werner Specifi fluid wes eruf snodified ed teeking systess en
e l
Page No.
26 l
06/07/90 l
SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORWECTIVE ComENTS REFEWEWCE TP/ FC No. NAME DATE NUMeER FAILURES PART NO.
CAUSE FL ACTION DOOMENTS tRN l
369 McGuire 1 09/19/85 85-028 one plus three Cable Post voteor 526-529 Persarmet no Att four Sielter volves sone no 11 incipients terminati occident 5-45 error vetves were checked et tmit on sempting (instettation
- repaired, 2, and foe.md to sceting not performed resented.
be okay per Wiring on ett instettation other Voicer specification) 526 series Sovs et station to be e, graded and seats restaced 369 McGuire 1 04/15/87 87-009 one Systen Mein turbine mot mot Modification we Change System mone Yes 00 perturbet Specified Spacift of design and maintenance operation logic ion ed pointenance-schedute to end time of avoid testing prevestive white et meintenance hed power.
6 d W.
Both factors contributed to e reector trip.
370 McGuire 2 06/24/85 85-018-01 Two (of the some Colt and Main sors-Wern mot 1-colt me 1-reptoced Second felture wcne Yes 01 SOV) stort feedwater er speciff feiture - not 50V.
2-dried occurred prior circuit ed soecified.
2-water from to complete short circuit
- SOV, instettotion of
- water spray electricot bon reptocement SUV ento open electricot box 370 McGuire 2 08/27/86 86-017 one Coll Main Borg mot mot Specified Yes Sov colt was mene LER ves 01 feedwater
'Werner Specift reptoced and 85-018-01 ed originot coit was sent to the manufacturer for anstysis.
3 73 Lesette 1 08/20***
- M1 One Sov (3 Electrice Mein steen Crosby IMF-2 Cause of short no Reptoced Sov Caused SRv to pone No 11 malfunctions)
I greurw! (MSRV)
Velve to ground not lift three specified tines e
4
+-
...w -
a
- Page No.
23 06/07/90 SOLEWO!D-OPERATED VALVE TAittsRE DATA DOC PLANT EVEmT LER me. OF FAILED SYSTEM MtWUFACT NODEL ROOF REP CON #ECTIVE COEEEEWYS REFERENCE TP/ FC No. NAME DATE NtpEBER FAlltsRES PART NO.
CAUSE FL ACTION 000DEEWYS OUT 346 Davis-sesse 12/07/87 87-015 One Sov instrisment ASCO 1179237 set specified no peptoced sov, Felture of 30v mene fev 21 instrumeret air caused toes of vented air dryer dryers instrueent air reptoced with eir/rmtor tygraded ones trip. 0-rings on severet 50Vs in turbine tyypass system else found degraded 348 Farley 1 01/18/87 87-005 Two not conteirs=mt AsCO 8316 Unknown so 1 sov closed Redundant sovs mene so 20 on additionet in one specified isolation attempts.
penetration (contairvient teboord SOW to falted to close simp be inspected discharge) stbsequent to shutdown.
mot mot Root cause of wo Att accessible 84 sovs et eech mone so 28 348 Farley 1 07/21/87 87-012 84 incipients at inedequot mot
$0vs'instettet smit were found each unit e
specified Specified Spuifi inedrepsete electrics ed sptices and ions modified not to be terminations to en approved instetted in t
not stated EO splice ord miv h e with instatt.
termination EO reepsirements (sptices/
configuration (splices and terminets on a priority jtmetion bon
)
besis.
cormections) 352 Limerick 1 05/09/88 88-017 one teeksge acector 8tdg Asco 8316 mot Specified #o Replaced S0W Licensee could mone me 20 not determine
-stog Wentitetion cause of 50v stuck in feiture.
mid-posit Cetted e ion
- ~,..;
felture of is* noun cause" 352 Linerick 1 03/14/89 89-019 0
Electrice RE building Design error Seeted Potentiet for No 07 t
wentIIetien (ES).
electricot consorMmede Inedequete conduits feltures failure /m conduit oisture seating for intrusion IIELS potentist erwironomt N
Page No.
24 06/07/90 SOLEW0!D-OPERATED WALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MueEL 9007
- EP CX3RWECTIVE CcusIENTS REFEREstE TP/ FC No. NAME DATE NUMBER FAILURES PART mo.
CAUSE FL ACTION DO m eTS inff 3% Mope Creek 08/28/86 86-063 12 incipients not Contelrunent ASCO NP8316 Desi p error so Septoced ett Felture of mone no 13 Specified Atmosphere tuetwe S0Ws fian-e Controt with ones regulators having a could heve higher MOPD caused feitures reting.
of the S0Ws.
3% Mope Creek 02/24/87 87-018-01 One Failed to Mein Steam Automatic Not Forei r No Reptoced Foreir LER No 03 shift (MSiv)
Velve Speciff meteriet feited SUV end senteriet in 87-037,038 Corp.
ed inside S0W its manifold 50W,Pimper in (AVC)
- body, essep6ty.
S0W not per manufacturing peptoced 7 design defect, and S0Ws for other (incorrect ino# quete MSIVs. Sent length),
instettation failed S0W to moteting screws stoptier (GE) on jtmetion box for onetysis were loose.
3% Mope Creek 10/10/87 87-047 One Failed to Mein Steam Target Not Inndequete No The Foiture c M Wone No 12 shift (MSRV)
Rock SpectfI protection of metfunctioning by intrusion of ed MStVs during SRV and its sentidssting plant SOW piece-port grit which was construction were re;teced used during in kind.
plant construction 361 San onofre 2 01/09/86 86-004 Two Coit Feedwater Not mot Moisture no The vetves mone mene Yes 11 specified Specifi intrusion -
were reptoced ed feutty conduit and visunt connection inspections made of the corw3uit connections of simiter S0Ws 361 San Onofre 2 12/17/87 87-031-01 One Corrosion Main Merotte MW233C Inedspete Yes Reptoced S0W, Water and LER Tes 12 of power Feeduster Scientiff /
meintence terminst foreim 206/96-004 teeds and MFIV) e MWZ38C instructions block,and meteriet terminst Controts power teeds.
Intrusion block Inc.
Seeted condtrit (inodspetely connections seeted conduit property.
conrwetion) 4 O
e Page No.
21 06/07/90 SOLE 4010-OPERATED WALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM 9WWIUFACT se00EL WOOT REP CORGECTIVE C55eEWYS WEFEWEwCE TP/ PC l
No. NAME DATE NUMBER TAILURES PART Wo.
CAUSE FL ACitou 00 Cur.sts tart 336 mittstone 2 01/02/87 87-002 One Diaphreese semin ASCO 8262 not specified Yes inspected and fee 02 teskoge feeduster replaced (TWRV) 338 North Anna 1 02/02/84 84-005 6 failed and 54 Electrica Contairment volcor vatcor Insequete Replaced 6 S0WS failed 99 incipients t
isotatim and ASCO 526seri cordsit failed Sovs and 54 Sovs taoistere ) hydrogen es seating and seated att were instatted intrusion controt/ pass methods did deficient incorrectly in
)
)
not meet afrs cordsit seats both units specs to meet IEEE-324 qualifications 338 worth Anna 1 11/23/87 87-020 Two not main Steam Copes-vut mot No*_ Specified no unter To prevent mene wo 02 Specified (AtmosgAeric can Spacifi induction recurrence of Dump vatwes) ed circuits were this type de-energired event, an in order to evatustion to start the instati condensate additIoneI ptmps and levet switches begin will be secondary performed.
systese recovery actions.
338 North Anna 1 01/08/88 88-002 One not Cordenser not mot mot Specified Yes acptaced Sov mone mone Yes 21 Specified waterben Specified Speciff vacutse ed 338 North Anna 1 03/11/88 88-011 Nine Stuggish Contairwent ASCO WP-1 Design error ses Reworked S0Ws Failure to LER Wo 14 operation isotation series to meet fotlow 339/87 manufacturer's manufacturer's 01 instructions instattation instructiens modified the Sors' performance and gsst ification.
Page No.
22 06/07/90 SOLEWOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT RIEP CORWECTIVE CGeENTS
- EFEREN M TP/ FC No. NME DATE NLMBER FAILURES PAET No.
CAUSE FL ACTION DoctMENTS OUT 338 North Anno 1 03/15/88 88-012 One Not Cogenent ASCO Wot Not Specified Yes SOV from None LEt 88-011 No 82 specified Cooting Specifi 1-CC-TV-1034 Water ed isos instetted on 1-CC-TV-1038, and the S0W from 1-CC-TV-103s ases refurbished eM instetted on 1-CC-TV-103A 338 North Anno 1 07/19/89 89-014 1
0-ring Turbog-narat Parker-No MRFN16M 0-ring pinched No Reptace 0-rtmp setementet LER 88-013 Yes 03 or (ENC) nnefin x0834 during SOV info obtelned refurbishment frem ticensee by turbine 5/16/90, N.L.
manufacturer's Ornstein/
meintenev e C.U. AtIen tese 344 Trojan 04/16/87 87-009 Not Reactor Net Not Design /instatt No Reptoced None None No 28 Specifled cootont specified specifI ation error satices iAich (PTV) ed did not meet EQ instettetion requirements 346 Davis-Besse 09/11/84 84-013-01 One Not Mein steam Contret Not Not specified Yes septoce or SOV is a Wone No 21 specified (Atmospheric Component specifi refurbish SOV piece-port of Vent)
Internati ed the atmospheric onet vent vetve's air-epereted controtter 346 Davis-sesse 01/03/86 86-006-01 Thirty tiso Coit mot ASCO Not Feiture to Reptoced 50W Colts on EQ Wone No TT incipients specifi M specifI perfora coiis S0Ws had been ed preventive in service maintenance beyond their wher. required quetifled lifetime O
6
~
e.
Page No.
19 06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER No. OF FAILED SYSTEM MANUFACT MODEL ROOF REP CORRECTIVE COMENTS REFERENCE TP/ FC No. NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DOCUMENTS SUT 327 Sequoyah 1 05/18/84 87-020 Not specified Not Not Not Not Design error No Plant 1E S0Ws were None No 14 Specified Specified Specified Specift modifcetions not protected ed to protect from water winerable 1E spray which equipment could emenete from pipes which were vulnerable to en SSE 328 Sequoyah 2 08/30/84 84-014-02 One Seat feedwater ASCO 8320 Design Error No Replaced Sov An incorrectly None No 13 seIected 507 ieekage fsited when PJt in service where its MOPD timits were esceeded 328 Sequoyah 2 06/11/88 88-026-01 Two incorrect Auxiliary not Not Ina& quete Yes Recomected incorrect Nene No 07 externet feedwater Specified Sp nift maintenance 50Vs correctly externat wiring wiring levet ed configuration to 2 SUVs controt contret 328 Sequoyah 2 06/06/88 88-027-01 Not Auxiliary Not Not inadequete Yes Reptoced None None No 07 Specified feedwater Specified specifi electricet diodes missing ed maintenance from externet circuitry comectIng 2 S0Ws No 12 331 Duane Arnold 01/10/86 84-006 Two Stocke1e Stantby ASCO 8316 Foreign Air path of filtration meterlat in eteened internet instrument air possegewe 331 Duane Arnotd 01/28/85 85-002-00 One Diophrsgo High Skimer L2D8515 End of No Reptoced S0W None None No 1T Y
pressure Electric 0 tife/ excessive cootent time bet:seen injection saintenance
Page No.
20 06/07/90 SOLEN 0!D-OPERATED VALVE FAILtJRE DATA DOC PLAuf EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORGECTIVE CD4EEwfS REFE9ENCE TP/ FC No. NAME DATE NUMsEt FAILURES PART NO.
CAUSE FL ACTION 000 AMENTS OUT 331 Duane Arnold 05/27/88 88-005 One mot Fire Electro-M 2010008 Design error No Reptoced SOV Licensee had None to M Specified Sw pression anuet 3
and inadequate tegraded SOV (Chemetro post with an n Corp.)
maintenance incorrect one.
testing Deficiency was not found during post maintenance testing.
331 Duane Arnold 03/05/89 89-008 one Colt Main steam ASCO we8323 Moisture no Reptoced SOV. 7 other similar Yes 11 (MSiv) intrusion free fifttened 50Vs wwe steem teak /
enclosure subject to inadequate covers of moisture torqueing of other similar intrusion enclosure SOVs.
felture due to fasteners c-.M torqueing deficiency 333 Fitzpatrick 08/20/85 85-022 One Electrica Main steam ASCO mot Maintenance no 50Vs replaced AC colt had None Yes 09 1 fault (MSIV)
Specifi personnet and rewired been connected ed error in correctly to DC source externet end DC colt had wiring been connected to AC source 333 Fitzpatrick 11/22/85 85-027-01 One 50V Main steam ASCO NP8323 aress stiver no Cteened/refurb MSiv unable to mone so 12 unable to (MSIV) die to cross Ished SOV close seat threeding air check other property line fitting for similar problem 333 Fitzpatrick 08/03/89 89-013 None Contairusent Design error Correct wiring to 07 isolation error 334 Beaver Valtey 1 06/07/88 88-007 One Not Diesel Johnson mot Not specified No Reptoced SOV EDC eir stort mene no 22 Specified generator Specifi 50V failed air start ed 336 Mittstone 2 12/31/86 86-021 Two Broken Reactor Veteor VS26-60 Suspect no Reptoced 17-7 Prior to event more so 03 springs Coolant Mead Engg 42-3A hydrogen PW springs of these 50Vs had i
in SOVs vent Corp.
embrittiement a1i simiter been Ieeking Valcor SOVs and had been isolated d
n
f Page No.
17 06/07/90 SOLENDID-OPERATED VALVE FAILtRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT PIPET.
ROOT REP CORRECTIVE CO MENTS REFEWEWCE TP/ FC NO.
NAME DATE NLMOER FAILURES PART Wo.
CAUSE FL ACTION 000 MEWTS OL,T 321 Match 1 03/18/87 87-005 Two
- 1. Missing Conteirment ASCO NP8321 t e ffled Tes 1. Instetted a 2 dumper LER mo 60 lock nut ventitation missing lock feltures. (1 85-015-01
- 2. stuck nut./ 2. No caused by planger corrective missing lock action taken cut on Sov,1 on stuck S0W caused by stuck because it SOV plunger) tested okay sthse p t to failure.
322 shorchem 11/15/89 89-009 0
Cont airment ASCO 206-832 Design error, Reorient Sovs Comuww mode No 05 isolation Sovs were to correct failures having (RX building 206-380 oriented positions potentist to i
stancR>y incorrectly (vertical vs. prevent ventitstion) horizontat) fulfittment of safety function 323 Diablo Canyon 2 C8/14/85 85-019-01 Three incorrect Main Steam Not None Personnet Yes Reptoced SOW Undetected 50V LER 85-014 #o 07 wiring to (MSIV)
Specified error (incorrec feiture caused SOV t urdocumented 5 montS toss of wiring change)
I trein of ESFAS octuotton of MSIVs 323 Diablo Canyon 2 12/21/85 85-022 One Open Feedwater mot Not Ingreper so the wiring SOV is a LER Yes 09 circuit specified Specifi wiring connection was pieceport of 275/85-030 ed instattotion property the FWRV and tuped reteriminated junction box other simiter SOVs*
terminettons were inspected.
324 Brunswick 2 09/27/85 85-006 Three Disc-to-r. Main steam ASCO 6323 Mydrocarbon, so Reptoced Sovs t w oode mone no 12 est (MSIV) water and high failures. See sticking temperatures Section 5.2.3.1 caused of this report.
degradetion of seat meteriet.
Page No.
18 06/07/90 SOLE 4010-OPERATED WALVE FAILIJRE DATA 00C PLANT EVENT LER NO. OF _
FAILED SYSTEM MANUFACT MtBEL ROOT K P CORWECT!vE Cop 54ENTS KFEREWCE TP/ FC no. #AME DATE tRJMBER FAILURES PAdi NO.
CAUSE FL ACTION DOCUMaTS OUT 324 Brunswick 2 10/15/85 85-011-01 Two DC colt mein Steam ASCO mP8323 Licensee me septoced 90vs. mone mene Yes et (MSIV) suspected Entensive chloride feiture corrosion anstysis initiated.
324 Brunswick 2 01/02/88 88-001-05 Four Failed to Contairment ASCO Still under Yes Replace 50Ws. Four previous Yes 19 shift isot./drywet investigation.
Perfornring simiter i floor and Fotruf debris entensive feitures had eget drain and oil film failure tm on one 50v.
enotysis esperienced sumps suspact high temperatures f rom set f heating of energized SUVs 324 Brunswick 2 06/17/89 89-009-01 One Tailed to crywatt ASCO mot Sespected that so Reptaced SUV Extensive me 12 shift purge and specifi foreign snetysis of went ed porticulates root cause was foted in the not totetty SOV had conclusive attacked etestomeric ports of the 50W 325 Brunswick 1 02/28/87 87-005-02 Two Discs Containment vetcor v52645-not Specified no neptoced 50vs 50v teoksee mone so 03 isotstion 5683-14 foted during LLRT 325 Brunswick 1 07/01/87 87-019 one Stuck Mein Steam Terget 1/2-SMS Escess Lectite Yes nefurbished See Section LER mo TT plunger (MSRV)
Rock
-A-01 used by 50t 5.2.2.2 of this 87-020-01 manufacturer's repo-t field rep 325 Brunswick 1 07/03/87 87-020-01 Four Stuck Main steem Terget 1/2-SMS Excess Lectite No Reptoced S0Ws See section LER 87-019 wo 1T plunger (MSev)
Rock
-A-01 used by 5.2.2.2 of this merusf acturer's report field rep ll
? o Page No.
15 06/07/90 SOLE 40!D-OPERATED VALVE FAILtME DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MWpEL ROOT REP CORRECTfwE CtpelEWYS REFEaEmCE 7P/ PC NO.
- AME DATE NUMBER FAlltMES PART NO.
CAUSE FL ACTION 90ClpEWIS tRff 305 Kewounee 05/28/88 88-007-01 Three plus 7 Failed to Contefrument ASCO NP8314 Montefacturirq po Cleaned and Initieted on LER se 65 refurbished entensive root 87-012-01 incipients shift isolation error (prr relief, (unouthorized the effected cause anetysis, ookety use of SCVs See Section isoletion) incorrect 5.2.4.1 ef this tiericent) report.
309 Maine Yankee 08/10/86 86-005-01 One crotnd Cardon Fire Cheaetron 5-020-0 mot Specified wo Reptoced 50V Sov fatture me 21 trimed Certbn fault Protection 074-8 system power systee stsyty breeker, thereby disabling the Cerden syste=e.
309 Maine YarAce 05/23/88 88-005-02 Four incipients not MPS!/chargin R.C.
620us24 Design error no Mafified Sovs in high mone no 16 Specified g ptsup Laure re DCSW system red. fields ret environ. quet.
suction vent Feiture could cause tswontrolIed reteese of radioactivity to non quet.
systems.
Main steen Ins +quete no Modified Testing Yes 16 311 Salem 2 05/22/89 89-011-01 mone surveittance testing deficiencies (isolation welve) testing circuitry would prevent detection of SOY feiture Deficiency existed et unit 2 etso 313 Amo 1 05/06/35 88-001 Two Lifting Post Target 80E-001 Design error No 50vs were Incorrectly LER Wo 06 of accidmt Sock
/81P-00 reoriented oriented SCvs 368/88-001 ptunger sampting Corp.
6m correctty coutd open upon seett increeees (spurious in ectuation beckpressure.
)
See Section 5.1.4 of this report
k Page No.
16 06/07/90 SOLE 40fD-OPERATED VAL'E FAILURE DATA -
00C PLANT EVENT LER WO. OF FAILED SYSTEM 84W8JFACT N0 DEL ROOT REP CORWECT!vE CopuqENTS REFEREWCE' TP/ FC NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACT!on DoctSEEWTS OtN 317 Calvert Cliffs 1 06/01/87 87-007-03 Four incipients Unquetiff Ataritiary Not Not Desi p error No Deficient Two 30Ws on None Yes 26 ed Feedwater Specified Specifi electrical eecit trtit fotaid electrica ed ceree-tions to have were upgro*d inadequete (EC)
I with E0 electrical connector quotifled ones connections 317 Calvert Cliffs 1 08/22/89 89-015 0
Iodine cesign error Replace with SOf failure no 15 s
fitter (o tist seiserical ty could prevent dousing classification quotified s0Vs iodine fitters system
)
from performing tf*eir fisiction 317 Calvert Cliffs 1 11/13/89 89-020 0
satt water Design error Reptoce with 4 Sovs in so 15 cooting (0 list seismicatty safety system classification quotified S0Ws not able to
)
and pw withstand sources seismic event pouar sources for 5 safety-related SOVs not seismicatty quotified 318 Calvert Cliffs 2 09/05/86 86-006-01 One seat Main steam Asco 8300 mot specified we 50v internets mone mone no 03 teskoge (atmospheric were replaced dtsy) 321 Match 1 12/07/85 85-043 01 zumber of falted seat containment mot mot normet Yes Lesking mone LER 86-017 to 18 50Vs not spec tenkege isolation specified specifi equipment use vetves in 42
-muttiple ed or weer penetrations repelred, rebut systems it, or replaced.
321 Hatch 1 04/15/87 87-004 One incipient Main controt Not Not AE design No Redeslyt sein single 50W sone so 14 room specified speciti deficiency contret room falture could envircemente ed emiterummtal compromise contret system contret room i control hability O
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13 06/07/90 SOLEWO!D-OPERATED VALVE FAILtRE DATA DOC PLANT EVENT LER WO. OF FAILED SYSTEM MmedFACT MODEL ROOT REP CORRECTIVE CUNEmis DEFEmEm m TP/ FC NO.
NAME DATE NUM8ER FAILtRES PART NO.
CAUSE FL ACTION DOCUMENTS intf 298 Cooper 08/18/86 86-018 One mot Weector mot not not Specified so not Specified mene mone so 21 Specified Recirculatio Specified Speciff n Systen ed 302. Crystet River 3 01/05/89 89-001-02 None Muttiple ASCO 8320/mP Design Yes Reptoced Sovs Se-section See to 13 systems 8316/83 error-m0PD with others 5.1.3 of this (Ws 20 having higher rgert for MOPD reting additionet info.
Reference doctsamts: LER 78-054,83-023, 88-013 302 Crystet River 3 04/07/89 89-012 conteirvamt ASCO 8320 Design erroc Reptoce Sov 8 Sovs were See no 14 isolation coils with effected.
comemts (RX cavity coils having Reference t ooling correct doctsamts: LER system) teaperature 78-054,83-023, retings88-013, 89-001 302 Crystet River 3 04/18/89 89-015 Reactor Inodaquete Modified Sov 15 cootont ptrp seiseie sigports seet bteed instatietion off 302 Crystet River 3 09/26/89 89-034 Electrica NWAC, Design error Modified penser Intermingling me 09 t power conteirvamt simplies of TE ervi supplies isolation, non-1E powar Mein stese sources to SOVs (MStv) 304 Zion 2 07/11/84 84-015 mot Spacified Internet Mein stese reene 51-170 Licensee could no Three Sovs to mone mene so - 26 teskoga (MSIV) not find cause be reptoced of failure with envirorumenteIt y quetifled S0Ws 304 Zion 2 08/09/85 85-015 Two
" Stuck"pi EDG building mot mot not specified Yes The vetwas Common-mode LER Wa 95 4et wetwe vent specified SpecifI were reptseed. feitures fo m d 295/85-029 ed during testing.
AIso eccurred on unit 1 the previous dey.
40 such volves on mits 1 and 2.
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14 06/07/90 SOLEmotD-OPERATED WALVE TAittNIE DATA DOC PLANT EVENT LEP.
NO. OF FAILED SYSTEM PlasUFACT 91000t.
WOOT REF COR#ECTIVE COIWEEWTS REFEWEW E TP/ FC 10 0. NME DATE IstsesER TAILURES PART 81 0.
CAUSE FL ACTION 00CUMEWTS WT-304 Zion 2 02/03/87 87-001 One 0-Ring
.sesta steen Chicago nSV1-16 stenufseturing to septoced sov Isone soone Yes SS (ses!Y)
Fluid
-C-NP defect or Power damage daring instettetion 305 Keweunee 07/02/84 84-013 One Colt Aunitiery Johnson V-24 mot Specified Yes The Johnson Sov feitures 82-03,28, so 01 vetves were to resulted in 81-34 buildirg specist be reptoced initiating with ASCO safeguerds wentilation IIP 8320 Sovs es egsipe 59 they f ailed.
such S0Ws rmining would be reptoced tith ASCOs.ed at next outage 305 Keweiswe 12/16/84 84-020 One Coit Aunitiery Johnson V-24 asurnt out" Yes The lehnson Due to LER 84-13 no 01 building coil, root SOY was repetitive special cause not reptoced with feitures of wee l8stion specified en ASCO these Johnson HP8320.
SOWS, they were ett being reptoced with ASCO IIP 8320 Sovs on en es-feit basis 305 Kewsunce 02/11/85 85-005 One Coit Auxiliary Johnson v-24 Colt aburnt Yes septoced SOY cue to LER mo 01 building out,* root with en Asco repetetive 84-013,020 special cause ret fattures of wentilation stated these Johnson Sovs, they were et1 beirg reptoced with ASCO NP8320 S0Ws on en es-feit bosis.
I 305 Kewsunee 11/28/87 87-012-01 Two failed plus Feited to Conteirusent ASCO ser8314 Design error. Yes Reptoce S0Ws See Section hone no 13 l
58 incipients shift Isoletion-Pr Conditions and correct 5.1.3 of this exceeded SOVs*
regulater report r
relief,moke-se0PD timits settings so thet MOPD up,tCDT retings wilt discherge ret be encecoed A
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11 06/07/90 SOLEa010-OPERATED VALW FAILtJRE DATA DOC PLANT EVENT LER
- 0. OF FAILED SYSTEM MAsuFACT RODEL ROOT REP CORWECTlwE CtpWEWTS WEFERESCE TP/ FC NO.
NAME DATE muMBER
?Altt*ES PART NO.
CAUSE FL ACTION DOCIJMENTS tRff 280 Surry 1 11/12/87 87-031 One Sov Containment sesseneite 3500 leproper so Secured sov viring to no 89 wiring isoletion n (Sov series instettstion unspecified SOY caused blocked unspecifi sechanicet isolation ed) binding of volve conteirament operator isolettets volve's operator 281 Surry 2 01/27/88 88 4 01-01 %
$0V Conteirament Target 86V-0C1 Cause of SOY no Repelr or Electricians mone no 26 teskoge isolatien(pr Rock /ASCO /206-38 teskoge not reptoce Sovs trying to essurizer 0
specified.
Isolete teeking Cause of wrong SOWS tifted vapor space senpting) tend tifting; wrong Iesds electricet maintenance W 5w.ml error
- so 12 281 Surry 2 02/02/88 88-002-01 Two seat Reactor vetcor v526-56 tapurities in 50Vs reptoced teekege coo:ent 83-19 reactor senpting cootent systee isoletion water prevented complete se.t closure 285 Fort Calhoun 05/01/86 86-003-01 Two Failure Waste ges Not Not Ferserviet Non Return S0Ws to Fait closed None No 22 positions Specified Sreeifi error e correct S0Ws had been of SOVs ed feiture changed to fait positions open, resulting reversed in voltese contret tank teskoge to munitiery building.
236 lewhen Point 3 02/11/87 87-002 One Colt Contaitument ASCO 8308 Not Specified Yes The feited The design of LER Yes if solenoid vetve no. 34 stetic 85-001-00 testege reptoced with irwerter was contret one of a improved to higher ettow isolation temperature of single design. 3 branch circuits simiter Sov if a short colts were circuit etso reptoced. develops.
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12 06/07/90
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SOLE 4010-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF -
FAILED SYSTE98 8thMUFACT IEODEL ROOT REP CORRECTIVE COMENTS PEFE8ENCE TP/ FC NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DOOMNTS OUT 293 Pilgrim 07/19/88 88-021 Four incipients Potentist Primary ASCO 8320 Design error to Reptoce Sovs Felture of mone me 13 for conteirment, and with ones-pm enceeding controt rm,+
NP8320 rated for regulator escutd MOPD turb btdg higher MOPD result in timits MVAC/SGTS inoperability of 4 S0Ws dJe to exceeding MOPD timits 293 Pilgrim 01/27/89 89-004 conteirnent ASCO WP8320 Repolted teoks Failure of 2 LER 89-002 Yes 21 isolation and reptoced 2 A0vs due to air SOVs system teoks.
2 S0Ws esere reptoced es a precautlen against exceeding MOPD limits of the SOVs 293 Pilgrim 05/03/89 89-015 One Colt Main steam Automatic 6910-02 " Random no Reptoced 50V Yes 01 (MSIV)
Wetwe 0
fetIure" essembty Corp.
(AVC) 295 Zion 1 08/08/85 85-029 Two
" Stuck" EDG building Not Not Not specified Yes Repteced S0vs 40 such vetves LEt no 05 pilot ventitetion specified specifi used in both 304/85-015 vetve ed tmits.
Commum-mode feitures fo m d during testing.
Additionet CMFs ocurred next doy et unit 2.
295 zien 1 01/12/89 89-001 One Failed to Ventitetion ASCO 8320 Weekened colt Yes Reptoced SOY LER 89-001 no 01 shift (service water buildirg)
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9 06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM mWUFACT MODEL ROOT WEP CORRECTIVE COMENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER FAILtJRES PART NO.
CAUSE FL ACTION 000fMENTS Otti 272 Salem 1 02/20/86 86-006 One greken Feeduster Not Not Installation No ecptoced wire None None Yes 09 wire (FURV) specifiad Specif error and and checked ed vibration simiter SOVs 2 72 Setem 1 04/08/86 86-007 Eighteen Electrice Post Not Not Desigrt/instalt No instati 18 SOVs on idone No 14 incipients t
accident Specified Speciff ation required units 1 and 2 comector samling ed error,inadeque cumectors had ins &quete te connectors s
instattation procedures 275 Diablo Canyon 1 01/02/85 85-001 Two SUV Main turbine Not Not Not Specified No replaced Sov mone Yes 21
- stuck (overspeed Specified Specifi open" protection) ed Cont oiment Not Not Procedurst No Perform Failure to None No 22 275 Diablo Canyon T 07/24/87 87-011 None isolation Spacified Specif f ina&quecies necessary verify ed verification. penetration upgrade isolation procedures subsequent to 50V replacement.
277 Peach Bottom 2 04/27/84 84-008 One Not Contsimant Asco 8320 Not specified No Reptaced SOY Potentist mone No 19 existed for a Specified Isotation single failure (SBGT) to have prevented the futfitaent of the safety function of the S8GT system 277 Peach Bottom 2 01/24/86 86-003 Two DC coils Main Steam Automatic Not Under No The falted DC Failure of 2 DC None Yes 19 (MSIV)
Valve specifi investigation solenoids were SOVs in 2 Co msny ed reptoced.
seperate lines caused closure (AVC) of MSIVs 277 Peach Bottom 2 05/29/87 87-006 Three Control room Piping No Reconnected Sample tinas to No 20 ventilation /
configuration tthing to SOVs three SOVs had radiation error property been connected incorrectly.
monitoring Affected control rooms at both inits 2 and 3
Page No.
10 06/07/90 SOLEWO!D-OPERATED V8LVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT Mt2EL ROOT REP CORRECTIVE CGNENTS REFEWENCE TP/ FC NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DoctMENTS OUT 277 Peach Bottom 2 10/05/89 89-023 One s trufing Mein steem Automatic 6910-20 Inadeepsete no Reptoced 30v Reference LERs See Yes 27 of SOV (MSIV) valve manufacturer's and revised 277/86-003, comments stug conveny insta1Ietion instei1etion 278/85-018, (AVC) instructions and 278/86-016 maintenance procedures 278 Peach Bottom 3 09/30/85 85-015-01 One Leeked ADS beckup Target Not Not Specified Yes septoced SOV Previous See No 03 nitrogan Rock Specifi with an simiter Ceauments ed upgraded one occurrences reported in LERs 277/85-01 and 278/85-C5 275 P*ech Bottom 3 07/11/84 85-018 One DC colt Main steem Automatic Not Reesen for Yes Task force DC Sov felture None Yes 01 (MSIV)
Velve Co. speciff colt feiture recesended consted with ed not specified testing of DC momentary loss solenoids more of AC power often and resulted in enetyre cause MSIY closure of future fattures.
27E Peach Bottom 3 07/19/86 86-016 One coil Main Steam Automatic Not Reason for Yes The de coit en simiter reactor See Yes 01 (MSIV)
Velve Specifi ccit failure each MSIV's serens in 1985 comments Corp.
ed not specified SOV was eruf (AVC) reptsced.
1986(defective de coit coupled with oc power interrtetion):
LERs 278/85-018, 277/86-03 280 Surry 1 03/28/84 84-007 None Unspecifi Feedwater Maintenance No Recorruected I A instrument air No 08 ed (FWRV) had been done lines to lines were withmst proper SOV connected to approved ports the wrong ports proce&sres of 5 SOVs et inadequate surry units 1 post and 2
, L meintenance testing e
e
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7 06/07/90 SOLENDID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MusufACT 8RBEL ROOT REP CORRECTIVE CtpWENTS REFERENCE TP/ FC NO.
NAME DATE NUMeER TAILURES PART NO.
CAUSE FL ACTION DOCUNENTS.0UT 260 Browns Ferry 2 06/06/89 89-018 one Valve Emergancy Setem 812-6 Corrosion Yes Reptaced SOV Licensee No 12 seats dieset debris from upgraded EDG ganerator starting air air system and air stert system performed maintenance on it prior to event but dabris uos believed to be there from before 261 H.B. Robinson 2 05/13/87 87-007 Two not Not ASCO Not Inedaquate Yes Instatt incorrectly None No 14 Spacified Specified Speciff installations correct seats installed ed of conduit concisit seats seeIs at entrance to several harsh envirorummt 1E quet8ffed SOVs.
Potentist for moisture intrusion 261 H.B. Robinson 2 07/15/87 87-020 One Electrica Feedwater Not Not Water trapped No Wire ues SOV is None Yes 11 i short (FWRV) specified Specifi in 50V repaired and piece-pert of ed condotet water removed FWRV from the condutet.
Other SOVs examined for simiter problems.
261 H.B. Robinson 2 11/05/87 87-028-01 Two SOV Dieset Not Not Internet waar No Reptoced SOVs $0V faltures None No 18 internets Generator Specified specifi caused wenting Starting Air ed of starti g air 263 Monticetto 10/25/89 89-032 One Loose Main steam Tighten No 09 terminst (Mstv) ternainst screw screw and inspect simiter SOVs
Page No.
8 06/07/90 SOLEW0tD-OPERATED VALVE FhittstE DATA DOC PLANT EVENT LER No. OF FAILED SYSTEM 9muufACT MODEL ROOT REP CORWECTIVE CXpWIENTS REFERENCE TP/ FC WO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION 90CISIENTS iRff 265 ound Cities 2 06/28/85 85-015 One not Reector verse See not Specified me 50V reptoced VGS-4422-U-10-3 mene no 20 Specified 8tdg. Vent.
comun=nt 1-3ec Systee 265 ound Cities 2 02/18/87 87-006 One mot Contaifunent ASCO 8317
" Solenoid Reptaced 50v S0W is no 21 specified vacutse rusted and piece-port of corroded" vacusse breeker (reeson/ source air test not stated) cylinder 265 ound Cities 2 09/18/87 87-012 One plus two Not Contairunent ASCO 831T Unkneesn Yes Not Specified $0V is LER 87-004 no 20 incipients specified vacutse piece-port of Relief vacutse breaker air test cytinder 265 ound Cities 2 12/10/87 87-020 One not Main Turbine Sperry F3-SDG4 Not Specified No Rplaced SUV mone mene -
Yes 02 Specified Control Vickers 54-0124 Fluid 265 ound Cities 2 04/06/89 89-001 One Turixmenerat No Rebuilt 50v Failed SOV LER 87-020 Yes 21 or controls turbine mester trip solenoid 266 Point Beech 1 06/01/89 89-003 One conteirunent ASCO 8302 Reptoce 50v wo 21 isototion (SC blowdown sancting) 271 verwont Yankee 08/18/87 87-009-01 wot Specified Seat Automatic ASCO 206-381 Dirt / corrosion Yes 50v cycied mone mene no 12 teskage Depressurire products from tion the air supply 272 Setem 1 12/31/84 84-029 One Faulty Feeduster ASCO Wot Not Specified Yes Reptoced SUV SOV is a mone Yes C9 electrica (FWRV)
Speciff piece-port of t
ed FWRV connectio n end seat teekage 272 Salem 1 01/31/86 86-003 One Seat Feeduster ASCO mot Probebty Yes Two Sovs uere SOV is a mene Yes 12 i'
teekage (FWRV)
Specifi contaminated replaced piece-port of ed air the FWRV. Dirt and moisture were detectad in air tines causing other associated failures O
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06/07/90 i
SOLEmotD-OPERATED VALWii FAILURE DATA j
DOC PtAuf EVENT LER WO. OF FAILED STSTEM MANUFACT MODEL ROOT REP (DRWECTIVE C!peqEmis REFEWESCE TP/ FC l
No. NAME DATE Ntpl8ER FAILURES PART me.
CAUSE FL ACTION 00C1pIENTS Otff l
l l
250 Turkey Point 3 01/13/85 85-002 One Cloggad not not not mot Specified no Cteened air Sletter mone so 17 l
SOV sir specified Spacified Specifi filters on occurrences:
l fitters ed this and other LER 250-84-034, t
simiter Sovs LER 250-84-031, in both units LEt 251-84-020, 3 and 4 LER 251-84-009, and LER 250-83-016 250 Turkey Point 3 01/27/86 86-005 Two not Main steam ASCO 8316 1 internet no Reptaced 1 2 ind= pendant mene Tes 09 Specified (MSIV) interference, SOV, fuse 50V faitures 1 bent contact block pins discovered pins at fuse were dJring testing.
block.
straightened MSI" cut & t on other SOV. be closed 250 Turkey Point 3 08/03/86 86-031 One not Auxiliary /ee ASCO 206-381 Water entering no SOV replaced Simiter See Tes 03 specified ergancy the 50V occurrences:
comment feedwater LER 251-84-020, and LER 251-84-009 250 Turkey Point 3 01/03/87 87-002 One Coit Component ASCO 8316 mot Specified so Replaced SOY mone no 01 Cooting Water 250 Turkey Point 3 09/13/87 87-023 One Internet Steam Target 300525-Feutty wires no not specified mone mone Tes 06 wiring Generator Rock 1
poing to Reed Blowdown switch 251 Turkey Point 4 07/15/87 87-015-01 One Cromd Contaifwient Not mot Deterioration no cleaned and 50V is e sene so 18 fault isolation Specified specifi of insutsting reteped wiring piece-port of i
(pressurizer ed tape fran comections A0V sanpt ing) anormel ageinga 254 ound Cities 1 02/05/85 85-001 Two Comactio NPCI sarksdete 178250M Faulty Repeir Failure of NPCI No 07 o to SOV C2D4 terminst terminet turbine tripend power comection and comections reset SOVs lead vibration a :d secure wJrestoSOV housing
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6 06/07/90 SOLEN 0!D-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER No. OF FAILED SYSTEM MANUFACT MWpEL ROOT REP CURRECT!WE CopWIENTS REFERENCE TP/ FC D0. #AME DATE NungER FAILURES PART NO.
CAUSE FL ACTION DOCUNENTS OUT 254 ound Cities 1 04/03/87 87-006-01 One viring Nigh serksdete 1019433 vibration /ined Yes Reptaced colts MPCI LER 85-001 no 07 connectio Pressure ACP1 ecpJete on foited SOV inoperable.
n to coit Cootent cormeetion/ine and three Reptoced 50V Injection dequate others colts with steport replaced et w eer sedel, imits 1 and 2 etso added wiring restraint to ett four Sovs.
255 Palisades 04/10/86 86-017-01 Three fait +
valve Reactor Terget 808-001 Metet shavings Yes Repelred SOVs Yes 12 three incipients seat Coolant -
Rock in valve seet and systess teakage (head went) area.
fIushed to remove remaining suetet showings 255 Palisades 01/14/87 87-001-01 Eight Inadequot Contairveent Not Not AE design No Isoletion None None No 14 e
isolation (hy Specified Specift error logic sedified isotation drogen ed togic monitoring) 259 Browns Ferry 1 07/03/86 86-022 Six incipients ECCS RocEwell/
Design error Remove air Potentist for No 14 Atwood supply to overpressurizin Morritt offected g low pressure octuator systeess dJe to tJse of non quetifled SUVs (sla in coch of three growns Ferry tmits) 260 Browns Ferry 2 08/31/87 87-007-01 Potentist Loss of Contairveent Not Not Design error Yes Reptoce SOVs Use of None No 14 falIures att 3 SOV Drywett Spectfied ScecifI with tpJetifled non-cpJetified units function Cor. trol Air ed ones SOVs could prevent prisery contairment isolation. Att 3 srowns Ferry tmits affected.
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--SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER Wo. OF TAILED SYSTEM MANUFACT MODE!
ROOT REP CORRECTIVE COMENTS REFERENCE TP/ FC -
90CtpENTS CUT No.
CAUSE FL ACTION-NO.
NAME DATE NUMBER FAILURES PART 219 Oyster Creek 10/14/84 84-022 Three Diaphrage Scram Not Not Instetted No Instatt caused stow None-No 2T Discharge specified specifi diaphreys diaphram closure of 3 vottsne ed backwards.
correctly and air-operated inadegJete SOV develop SDV vent and rebuilding and improved drain valves inadequate post-mointenen post-maintenan ce testing ce test 220 Nine Mile Pt 1 06/14/84 84-013 Three Seat Main steam Dresser /C 1525Vx Wear and Yes 1 refurbished, Retest of att 6 LER 84-014 No 03 ieakage(2 Line onset.
centaminents 2 reptaced wetves found att to be
),misposi Electroma suspected tesking due to tioned tic meteriet todged wires in the seat area (see LER 84-014) 220 Nine Mile Pt 1 06/17/84 84-014 Six 5 seat Main steam Dresser / 1525 Vx Foreign Yes Cleaned and Retest of att 6 84-013 No 12 teakage /
Consot.
material refurbished SOVs (LER 1 stuck Electroma intrusion SOV2 84-013) found att to be open due tic (source not teeking due to stated) to forelyi foreign meteriet todged mati in the seat aree None No 03 220 Nine Mile Pt 1 11/01/85 85-021 One plus two Jammed Main steam Dresser /C 1525VM West Yes Reptaced att three vetves incipients springs onsot.
Electroma tic 237 Dresden 2 07/17/87 87-023 One Internet Feedwater ASCO 8300 Wear Yes Replaced SOV $0V is a None Yes 18 piecepert of passagewa (FWRV) the fWRV.
Y restricti 245 Mittstone 1~
12/24/85 85-034-01 Between three 1 core Contrci rod Asco Not Deterioration Yes SOWS rebuilt, Failure of Wone No 17 on and six
- spring, drive specifi of the 8tsie-N upgraded SPSV three controt ed discs and a maintenance rods to scram detached program per CE was attributed many spring.
SIL 128 to fatture of-discs three to six associated seram pitet solenoid valves.
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4 06/07/90 SOLEN 0ID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM 9NHRJFACT MODEL ROOT REP CORRECTIVE COMENTS REFERENCE TP/ FC ~
No. NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTICW DOCUMENTS OUT 245 Mittstone 06/06/87 87-015-02 One Excessive Contaffment Target Not Pitnger tthe No Reptoced None.
None No 03 teakage isolation. Rock Specift scored plunger tthe post ed accident sanpting 247 Indian Point 2 01/04/84 84-001 One Failed Containment ASCO Not Not Specified No Replaced SOY None None No. 21 closed purge Specifi ed 247 Indian Point 2 11/27/84 84-022 Two Not AFW Steam Not Not Not Spectiled No Reconnected SOVs control None No 09 Specified Specified Specifi power tends to ATW turbine ed SOVs inlet steam iso!ation valves 247 Indian Point 2 02/02/87 87-003-01 One Stuggish Condensate Not Not Design No Entargad S05' SOY controts None No 24 performan (storage Specified Specifi deficiency crifice aid A0V. Slow ce tank ed (stzing) eteened ctosure isolation) regulator attributed to orifice size.
Debris could have also contributed.
FStG454 crease No Reptaced SOV SOV controts None Yes 04 249 Dresden 3 01/12/85 85-001 One Manual Main turbine Sperry ~ 012A contsimination overspeed trip operator Vickers 249 Dresden 3 08/07/87 87-013 One Coit Feedwater ASCO 8300 Shorted coit No Replaced SOV SOV controts None Yes 01 FWRV air operator 250 Turkey Point 3 12/02/84 84-031 One
- Not Containment Asco Not Not Specified No Replaced SOV LER250/84-No 03 Specified isolation specifi vetve 09,020 (nitrogen ed supply) 250 turkey Point 3 12/13/84 84-034 One Not CVCS ASCO Not Yes Replaced SOV SOV contrets See No 02 specified (isolation Specifi A0V. Ref.
Comunents valve) ed Doctaments: LER 250/84-032, 251/84-009,84-0 20 O
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1 06/07/90 SOLEN 0!D-OPERATED VALVE FAILURE DATA 4
DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE ComENTS
. R8_FERENCE TP/.rc NO.
CAUSE FL ACTION DOCUMENTS OUT NO.
NAME DATE NUMBER FAILURES PART 206 San onofre 1 12/30/86 86-014-01 One Ground Feedwater & Not Not Moisture in No New Junction Corrective LER 87-001 No 11 box instatted action taken on
- fault, Safety Specified specifi junction box failed Junction.
moisture injection ed box a d seven in System other junction vulnerable box ones.
206 San Onofre 1 01/17/87 87-001 One Ground Feedwater inadequate Yes Eliminated Vibration No 07 instattation/v ground, tighten caused fautt ed connections loosening of ibration terminal box conduit tocking ring 206 San Onofre 1 11/10/87 87-016 Five faltures of Stug Containment ASCO 206-380 Lubricant Yes Secured SOVs Cause of Insp Ppt No 05 four vatves sticking Isotation, suspected in safety sticking under 89-24 position and investigation Containment initiated Spray weekly testing 206 San Onofre 1 12/01/87 87-017 Two Not safety Not Not Unknown No Repaired or SUV required
~None No 19 Specified injection Specified Specifi replaced SOV for venting SIS to avoid water vent ed hanumer Yes The ground was The toose See No 11 206 San onofre 1 12/16/87 87-018 One Ground Plant Not Not Loose screws fautt cooling Specified Speciff and inadequate eliminated by screws were comunents moisture water ed seat. Root removing the probably cause not
. water inside stripped from in Soy housing specified the solenoid excessive housing and tightening.
resenting the Ref. Docs. LERs housing.
206/86-014/01, and 361/87-001,031 206 San onofre 1 02/15/88 88-004-02 One SOV Safety Terget 80EE-00 Stitt under Yes SCV was SOV falture LER No 19 sleeve Injection Rock 1
investigation replaced.
prevented bleed 206/81-020 Modifled off from double and maintenance disc gate valve position procedures (inc bonnet.
indicatio tuding n switch implementation of mfr's reconsmend for new reed switch calibration ab k
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2 06/07/90 SOLEWID-OPERATED VALVE FAlltRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE CIMENTS
- REFERENCE TP/ FC.
NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DOCUENTS OUT Containaent Design error Design Discovered thet-1 14 206 San Onofre 1 03/03/89 89-006 modification a singte Sov fire made
.could, degrade suppression contairment spray system,resultin g in contairveent overpressure during a LOCA 206 San onofre 1 08/23/89 89-026 One Failed to Recire ASCO 206-380 Suspect Yes Replaced SOV LER 87-016 No 05-tubricant
- shift, system
" sticking (safety stug" injection /co ntainment spray) 213 Haddam Neck 11/02/84 85-005 Two Failed to Auxilia.y ASCO WP8320 Unknown No SOV retested SOVs failed None to 05 acceptably, during testing.
shift Feedwater declared SOVs required
" stuck". System operational, for more frequent auto-initiation cycling tests of AFW i
planned 213 Haddam Neck 09/10/85 85-024 One Failed to Auxiliary ASCO NP-8320 Unknown Yes Replaced SOVs. Cause of LER 85-005 No 05 Initiated more sticking has l
shift,"st Feedwater frequent not been uck" System periodic determined.
cycling Same SOVs as in LER 85-005 213 Haddam Neck 01/14/88 88-001 Four incipients SOY Contaironent Not Not Design No Corrected Installed SUVs None No 06 operating Isolation - Specified Specifi Deficiency circuit close teen mode Steam ed design, rather deenergizing than changing instead of Generator the 50Vs opening teon Stowdown deenergizing per design.
Condition existed for
. seven years O
e u
I APPENDIX A t
FAILURE CATEGORIES OTHER 00 i
COIL FAILURE 01 VALVE BODY FAILURE / LEAKAGE 02 0-RING / GASKET / PLUG / SEAT / DIAPHRAGM / SPRING FAILURES / LEAKAGE 03 LUBRICANT / LUBRICATION 04
'" STICKING" 05 INTERNAL WIRING / REED SWITCH / CONTACTS 06 EXTERNAL WIRING 07 INSTALLATION / MAINTENANCE ERROR-PHYSICAL (BACKWARDS, UPSIDE-DOWN, etc.)
08 INSTALLATION / MAINTENANCE ERROR-ELECTRICAL (LOOSE CONTACTS, AC vs DC, etc.)
09 EXCESSIVE ENVIRONMENT TEMPERATURE' 10 MOISTURE INTRUSION (ELECTRICAL SHORTS / GROUNDING /0 PEN CIRCUITS) 11 CONTAMINANTS (DIRT, WATER, RUST, HYDROCARBONS, DESICCANTS, etc.)
12 M0PD (MAXIMUM OPERATING PRESSURE DIFFERENCE) 13 DESIGN ERROR (OTHER THAN M0PD) 14 EQUIPMENT QUALIFICATION-SEISMIC 15 EQUIPMENT QUALIFICATION-RADIATION 16 INADEQUATE MAINTENANCE / EXCESSIVE TIME BETWEEN REPLACEMENT OR OVERHAUL 17
[
"END OF LIFE"/ NORMAL WEAR 18 "STILL UNDER INVESTIGATION" 19
" UNKNOWN" 20
" UNSPECIFIED" 21
" PERSONNEL ERROR" 22 REQUIRED CLOSING /0PENING TIME SPECIFICATIONS NOT MET 24 i
LEAKAGE UNSPECIFIED 26 ASSEMBLY ERROR (PLUG / DIAPHRAGM / SPRING etc.)
27 EQUIPMENT QUALIFICATION (ELECTRICAL) 28 I
_(
w Information Notice Number Date Title Information Notice 80-11 March 14, 1980 Generic Problems with ASCO Valves in Nuclear Applica-tions Including Fire Protection Systems Information Notice 80-39 October 31, 1980 Malfunction of Solenoid Valves Manufactured by Valcor Engineering Corporation Information Notice 80-40 November 7, 1980 Excessive Nitrogen Supply Pressure Actuates Safety-Relief Valve Operation to Cause Reactor Depressurization i
Information Notice 81-29 September 24, 1981 Equipment Quantification L
Testing Experience, Equip-ment Qualification Notice No. 1 l'
Information Notice 81-38 December 17, 1981 Potentially Significant Equipment Failures Resulting from Contamination of Air-Operated Systems Information Notice 82-52 December 21, 1982 Equipment Environmental i-L Qualification. Testing Expe-rience - Updating of Test Summaries Previously Published in IN 81-29 Information Notice 83-57 August 31, 1983 Potential Misassembly Problem with Automatic Switch Company (ASCO) Solenoid Valve Model NP 8316 Information Notice 84-23 April 15, 1984 Results of NRC Sponsored
- Qualification Methodology Research Test on ASCO Solenoid Valves Information Notice 84-53 July 5, 1984 Information Concerning the l'
Use of Loctite 242 and Other Anaerobic Adhesive Sealants Information Notice 84-68 August 21, 1984 Potential Deficiency in Improp-erly Rated Field Wiring to Solenoid Valves PRELIMINARY CASE STUDY C-2 4
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e APPENDIX C Generic Communications on SOVs Bulletin Number Date Title Bulletin 75-03 March 14, 1975 Incorrect Lower Disc Spring and Clearance Dimension in 8300 and 8302 ASCO Solenoid ValvesBulletin 78-14 December 19, 1978 Deterioration of Buna-N Components in ASCO Solenoids Bulletin 79-01A June 6, 1979 Environmental Qualification of Class 1E Equipment (Deficiencies in the Environmental Qualification of ASCO Solenoid Valves)
Bulletin 80-14 June-12, 1980 Degradation of BWR Scram Discharge-Volume Capability Bulletin 80-17 July 3, 1980 Failure of 76 of 185 Control Rods to Fully Insert During a Scram at a BWR Bulletin 80-17 July 18, 1980 Failure of 76 of 185 Control Rods Supplement 1 to Fully Insert During a Scram at a BWR Bulletin 80-17 July 22, 1980 Failures Revealed by Testing Subse-Supplement 2 quent to Failure of Control Rods to Insert During a Scram at a BWR Bulletin 80-23 November 14, 1980 Failures of Solenoid Valves Manu-
.factured by Valcor Engineering Corporation Bulletin 80-25 December 19, 1980 Operating Problems with Target Rock Safety Relief Valves at BWRs PRELIMINARY CASE STUDY C-1 4
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-l Information Notice Number Date Title Information Notice 85-08 January 30, 1985 Industry Experience on Certain Materials Used in Safety-1 Related Equipment-Information Notice 85-17 March 1,'1985 Possible Sticking of ASCO Solenoid Valves Information Notice 85-17 October 1, 1985 Possible Sticking of ASCO Supplement 1-Solenoid Valves Information Notice 85-47 June 18, 1985 Potential Effect of Line-Induced Vibration on Certain farget Rock Solenoid-Operated Valves Information Notice 85-95 December 23, 1985 Leak of Reactor Building Caused by Scram Solenoid Valve Problem Information Notice 86-57 July 11, 1986 Operating Problems with Solenoid Operated Valves at-Nuclear Power Plants Information Notice 86-72 August 19, 1986 Failure of 17-7.PH Stain-L less Steel Springs in Valcor Valves Due to Hydrogen Embrittlement Information Notice 86-78 September 2, 1986 Scram Solenoid Pilot Valve (SSPV) Rebuild Kit Problems L
'Information Notice 87-48 October 9, 1987 Information Concerning the Use of Anaerobic Adhesive /-
Sealants t
Information Notice 88-24 May 13, 1988 Failures of Air-Operated Valves Affecting Safety-Related Systems L
Information Notice 88-43 June 23, 1988-Solenoid Valve Problems l
Information Notice 88-51 July 21, 1988 Failure of Main Steam Isolation Valves
'Information Notice 88-86 March 31, 1989 Operating with Multiple l-Supplement 1 Grounds in Direct Current Distribution Systems L
I PRELIMINARY CASE STUDY C-3
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Information Notice Number Date Title i
l Information Notice 89 March 15, 1989 High Temperature Environ-ments at Nuclear Power i l,.
Plants L
Information Notice 89-66 September 11, 1989 Qualification Life of~
Solenoid Valves-Information Notice 90-11--
February 28, 1990 Maintenance Deficiency Associated with Solenoid Operated Valves Circular Number Date Title i
Circular 81-14 November 5, 1981 Main Steam Isolation Valve Failures to Close i
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' PRELIMINARY CASE STUDY C-4 l
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