ML20055C950
| ML20055C950 | |
| Person / Time | |
|---|---|
| Issue date: | 06/14/1990 |
| From: | Novak T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Gibson A, Hodges M, Miller H, Rossi C, Shao L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III), Office of Nuclear Reactor Regulation, NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| NUDOCS 9007020211 | |
| Download: ML20055C950 (2) | |
Text
_ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _
.i l
'1 JUN 1! 1M 1 s, MEMORANDUM FOR:
Charles E. Rossi, Director, DOEA, NRR Lawrtace C. Shao, Director, OE, RES M. Wayne Hodges, Director, DORS, Region 1 Albert F. Gibson, Director, DORS, Region 11 Hubert J. Miller, Director, DORS, Region 111 L. Joseph Callan, Director, DORS, Region IV Roy P. Zimmerman, Director, DRSp, Region V FROM:
Thomas M. Nova h Director Division of Sa$ety Programs Office for Ana sysis and Evaluation of Operational Data
SUBJECT:
REQUEST FOR PEER REVIEW COMMENTS - PRELIMINARY CASE STUDY REPORT ON SOLEN 01D VALVE PROBLEMS AT U.S. LIGHT WATER REACTORS A preliminary AE00 case study re) ort, " Solenoid Valve Problems at U.S. Light Water Reactors," is enclosed. Tie study analyzes and evaluates operational experience and safety implications associated with failures and degradations of solenoid-operatedvalves(S0Vs)atU.S.LWRs.
It focuses upon the vulnerability of safety-related equipment to common-mode failures or 3
degradations of SOVs.
The report presents information on more than 25 events in which common-mode failuresordegradationsofover600SOVswereaffected,orhadthepotential,h to cffect, multiple safety systems or multiple trains of individual safety systems. Although plant safety analyses do not address such common-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 recommendations which, if implemented, should reduce reactor accident risks by reducing the likelihood for common-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, INPO, NUMARC, NSAC, and vendors who provided input to the case study, with a copy of the preliminary report for review and comment. We request that you focus your l
}l>, "l NRC FR.E CENTER COPY
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'o Multiple Addressees review primarily on the accuracy and completeness of the technical details (i.e., coments are being solicited on the technical accuracy of the report).
The findings, conclusions, and recomendations are provided for your information in order that you may understand the significance we place on these events and, therefore, obtain a more complete picture of the total report.
Changes to the findings, conclusions, and recomendations will be considered only if the underlying information concerning the details of plant design or systems operacion is in error. We ask that coments be provided by menorandum.
Since we wish to finalize and issue the report shortly, we ask that any coments be received by us within 30 days from receipt of this preliminary report.
Should your office require additional time beyond that point, please let us know; otherwise, it will be assumed that you have no coments.
If you or your staff have any questions regarding this study, please feel free
,to contact me or Dr. Hal Ornstein at (301) 492-4439.
Origin 31 LI nod by:
G Thouns L:, g;oy;3; Thomas M. Novak, Director Division of Safety Programs Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated cc w/ enclosures:
T. E. Murley, NRR E. S. Beckjord, RES T. T. Martin, RI S. D. Ebneter RII A. B. Davis, Rlll R. D. Martin, RIV J. B. Martin, RV Distribution:
PDR SIsrael MW1111ams Central File Plam MTaylor, EDO ROAB R/F JRosenthal RSavio, ACRS DSP R/F EJordan AEOD R/F Dross H0rnstein TNovak fl0rw0 W
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- DSPyEOD OD 6/1)/90(,7h Plam JRosenthal TNovak H0rnstein:as 63/90 6/
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1.
PRELIMINARY CASE STUDY REPORT SOLEN 0ID VALVE PROBLEMS AT U.S. LIGHT WATER REACTORS June 1990 4
Prepared by:
Dr. Harold Ornstein Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data U.S. Nuclear Regulatory Comission
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g, TABLE OF CONTENTS
.P.,ag EXECUTIVE
SUMMARY
vii 1
INTRODUCTION....................................................
1 2
DESCRIPTION OF EQUIPMENT........................................
3 3
USE OF SOLEN 010-OPERATED VALVES (SOVs)..........................
8 4
SOLEN 0ID-0PERATED VALVE FAILURE MODES: APPARENT AND ROOT CAUSES.
10 5
OPERA 11NG EXPERIENCE:
SIGNIFICANT EVENTS INVOLVING Com0N-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 5.1.1.2 MSIVs at Crystal River 3 - Thermal 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 5.1.3 Maximum Operating Pressure Differential (MOPD) -
Multiple Plants.....................................
15 5.1.4 Directional SOVs....................................
20 5.1.4.1 Incorrect Valve Orientation at River '6end..
21 5.2 Maintenance................................................
21 5.2.1 Maintenance Frequency...............................
22 5.2.1.1 Dresden 3 - BWR Scram System - Primary System Leak Outside Containment............
22 l
5.2.1.2 Perry - Simultaneous Common-Mode Emergency Diesel Generator Failures........
24 5.2.2 Replacement Versds Rebuilding.......................
24 5.2.2.1 MSIVs at Perry - Inadequate SOV Rebuild.....
24 5.2.2.2 Brunswick 1 - Safety Relief Valves -
SOV Rebuilding Error:
Excess Loctite.......
25 iii
TABLE OF CONTENTS (Continued)
.P.ajLe 5.2.2.3 Peach Bottom 3 - Scram System - 50V Rebuilding Error:
Excess Lectite...........
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 5.2.3.3 Susquehanna 1 and 2 - Scram System: 011 and Water Contamination.....................
31 5.2.4 Lubrication..........................................
32 5.2.4.1 Multiple Plants - Manufacturing Error:
Residue-Producing Lubricant.................
32 with Vaseline.......y Air and Lubrication Catabwa:
Poor Qualit 5.2.4.2 34 5.2.4.3 Common-Mode Failure of 16 MSIVs at a Two Unit Station (BWRs):
Incorrect Lubrication.
35 5.2.4.4 Grand Gulf 1. LaSalle 1, and River Bend MSIVs - Sticking SOVs - Foreign Unidentified Sticky Substance (FUSS) - Lubricant Suspected...................................
36 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 5.4.1 Colt /Fairbanks - Morse EDGs:
Repetitive Air Start Valve Failures.................................
40 6
ANALYSIS AND EVALUATION OF OPERATIONAL EXPERIENCE................
42 6.1 Common-Mode failures........................................
42 6.2 SOV Failure Rates...........................................
43 6.3 Maintenance Problems........................................
44 6.3.1 Maintenance Problems - SOV Manufacturer's Contributions........................................
44 6.3.2 Maintenance Problems - Contribution of the Unrecognized 50Vs'....................................
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 a
.o.
TABLEOFCONTENTS(Continued) t 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 Energiration.............................
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 Rebuildin 52 7.2.3 Contamination..............D 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 8
CONCLUSIONS......................................................
55 8.1 Safety Significance.........................................
55 8.2 Need for Action.............................................
56 9
RECOMMENDATIONS..................................................
57 l
9.1 Design Verification........................................
57
\\
l 9.1.1 Ambient Temperatures.................................
57 9.1.2 Heatup From Energiration.............................
57 9.1.3 Maximum Operating Pressure Differential..............
57 9.1.4 Unrecognized SOVs Used as Piece-Parts................
57 l
9.1.5 Directional SOVs......................................
57 l
- 9. 2 Maintenance................................................
57 9.2.1 Frequency............................................
57 9.2.2 Replacement Versus Rebuilding........................
58 1
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e T(BLE OF CONTENTS (Continued) f.!E 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:
1964 1989................
A-1 B
Disposition of ASCO Dual-Coil 8323 SOVs Used for.........
B-1 MSIV Control C
Generic Communications on SOVs...........................
C-1 k
vi
J EXECUTIVE
SUMMARY
The study analyzes U.S. light water reactor (LWR) experience with solenoid-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 or multiple trains of individual safety systems.
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.
The events in which comon-mode failures of SOVs have affected multiple l
trains of safety systems or multiple safety systems are important precursors.
They indicate that actions are necessary to assure that important plant systems 1
function as designed in accordance with plant safety analyses, and that plants arenotsubjecttounanalyzedfailuremodeswiththepotentialforserious consequences.
The report analyzes the operating experience and it outlines the root causes of common 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 SOV failures are the users' lack of knowledge or understanding of SOVs' requirements or capabilities, such as:
50Vs' intolerance to process fluid contamination; the necessity for preventive maintenance or changeout; and the propensityforrapidaginganddeteriorationwhensubjectedtoelevatedtempera-tures.
Compounding the problem is the fact that some 50V manufacturers do not provide the users with adequate guidance regarding proper SOV maintenance and operation.
Further complicating the situation is the fact that many SOVs 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
The report addresses widespread deficiencies which were found in the areas l
l of:
design / application, maintenance, surveillance testing, and feedback 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; i.nd (5) verify that all SOVs which are used in safety-related applications have been manufactured, procured, installed and maintained comensurate with their safety fun ~ction to assure operation consistent with plant safety analyses.
Specific technical information supporting these broad recommendations is contained throughout the report.
Detailed recommendations are provided in Chapter 9.
PRELIMINARY CASE STUDY vii
{
In addition, it is recommended that an industry group such as INPO take action to improve the mechanism for feeding back SOV failure data to the manu-facturers for early detection and resolution of potential generic problems.
1 PRELIMINARY CASE STUDY viii l
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 ditions. perate with hydraulic and pneumatic fluids under a wide variety of con-used to o They are used to control process fluid either directly, or indirectly as pilot controllers.
It has been estimated 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 Federel Reculations, Part 50 (10 CFR Part 50) Appendix B, and 10 CFR Part 21.
However, we have also found manycasesinwhIchplantsusecommercial,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 50V 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 i
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 MSIV failures at Perry, Brunswick, Grand Gulf, LaSalle and River Bend AFW System degradation at Calvert Cliffs and Horth Anna Losses of containment in'tegrity at Kewaunee, North Anna, and Brunswick l
BWR scram system component failures at Susquehanna, Brunswick and Dresden Safety Injection System degradation at Calvert Cliffs PRELIMINARY CASE STUDY 1
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Chapters five and six of this study provide comprehensive reviews and i
I 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.
4 PRELIMINARY CASE STUDY 2
2 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 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-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 home 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, i
PRELIMINARY CASE STUDY 3
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PRELIMINARY CASE STUDY 4
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PRELIMINARY CASE STUDY 5
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PRELIMINARY CASE STUDY 7
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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 (ADVs).
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 SOV 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 application that is determined by the utility, nuclear steam systet supplier, and architect enginet*;-their specific utilization is not a licensing requirement.
Table 1 lise u..ny of the systems that use SOVs at U.S. LWRs.
PRELIMINARY CASE STUDY 8
i
o
. g Table 1 Systems Which Use SOVs at U.S. LWRs 1.
PWR Rod Control 3.
Reactor Coolant (RCP seal) l 4.
SafetyInjection 5.
Primary Containment Isolation 7.
High Pressure Coolant Injection / Reactor Core Isolation Cooling 8.
High Pressure Injection P.
Automatic Depressurization 10.
Emergency Diesel Generator 11.
Instrument Air 12.
Chemical Volume Control / Charging and Letdown /Boration 13.
Pressurizer Control 14.
Steam Generator Relief (PORVs, ADVs) 15.
Low-Temperature Overpressurization Protection I
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 Drywell/ 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.
Containmec
~.re/ Containment Spray 30.
Standby G6s :"et.6 ment 31.
Floor /Sume Di :. i r.
32.
Sampling aormal and cost-accident) 33.
Fire Supur sion 34.
Turbine /r e otor 35.
Reactor V alm: Fan 36.
Containr:
Ah Lcat 37.
Leak Det e:io 38.
Radwaste PRELIMINARY CASE STUDY 9
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SOLEN 0ID-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 niA causes of most (approximately 75 percent) of the 30V failures reportM w Mh Mtween 1984 and 1989 are given below:
a.
Coil fallon or burnout that ns attributed to design or manufacturing deficiencies (early failure /erJ d life) or an error in application (type of current, voltage level, environmeM41 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 /intemal 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 energized 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%]
L 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%)
1 PRELIMINARY CASE STUDY 10
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 s
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 L
LER data base.
l Many individual SOV failures not reported in the LER data base are reported-in the Nuclear Plant Reliability Data System (NPROS) data base.
Reference 1 L
noted that for 1978-1984 data, all SOV failures reported in LERs were also reported in NPRDS.
5.1 Design 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-g l
tions relevant to design application errors are provided in Sections 7.1 and 9.1 respectively.
5.1.1 Ambient Temperatures 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 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 "0" 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 tiie Technical Specification allowable times.
i l
PRELIMINARY CASE STUDY 11 1
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m Becaute of continued NRC concerns about MSIV reliability, the licensee shut down the plant and established a plan to find the root cause of the MSIV fail-ures (Refs. 6, 7, 8).
Intense investigative efforts were conducted by the util-1 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 S0Vs 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 S0Vs as a result of several steam leaks.
Originally, hydrocarbon intrusion was suspected as having contributed to the degradation of the EPDM seats and discs.
It was not until microscopic and spec-i 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).
l 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 SOVs 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 l
2's environmental qualification program recognized a significant shortening of l
the qualified lifetime of eight Valcor S0Vs 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 SOVs.
The licensee determined that the increase in ambient temperatures from 120 F to 157*F shortened the lifetime of the S0Vs 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 since 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
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 S0V, 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 50V' port screen.
The licensee concluded that the piece had been lodged in the s internals, thereby keeping the SOV 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 S0Vs piloting the MSIVs disclosed that all eight had degraded seats.
Initial visual inspection did not reveal the degradations, which became apparent under microscopic examination.
The EPDM seats of all eight SOVs had cracks.
- However, on six of them, the raised portion of the seat, formed by the annular impression made by the seat of the exhaust port, was missing.
It appeared that six of the eight 50Vs 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 forces when the normally energized SOV 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 S0Vs, but tearing of the discs had not been observed previously.
It is believed that the tearing and overall degradation of the dual-coil S0Vs' 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 inside 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 S0Vs.*
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 providin nuclear qualified SOVs (NP series)g licensees with heat up data for all their (Ref. 19).
- 0ther EPDM discs in the same 50V 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
.o 5.1.2.2 North Anna 1 and 2, and Surry 1 and 2 - Thermal Aging (Self Heating l
h Due to Energization)
L 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-l ficant reduction in the qualified life of the S0Vs.
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 pn.vious analyses,125 SOVs would require replace-
'3 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 i.
isolation functions.
The systems affected were:
SafetyInjection, Reactor l
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, i
Similarly, Surry 1 and 2 required early replacement of 58 ASCO SOVs because of self heating.*
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:
-l "NRC and utilities are aware of this issue to some extent."
In Reference 20, the licensee noted that it had learned of this problem initially from discussions with " industry representatives" at Equipment Qualification (EQ) seminars in j
l' 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 (M0PD) can cause an 50V to malfunction.
When the S0V is in the de-energized position, pressurized fluid enters the valve at port 2 and is l1 blocked by the core assembly.
If the pressure differential between ports 2 and 3 exceeds the MOPD, the overpressure could lift the core assembly, resulting in leakage of fluid from port 2 to port 1 and port 3.
l 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 L
.de-energized position (block off po'rt 2).
]
- Telecopy communication between W. Murray, Vepco, and H. L. Ornstein, USNRC, December 19, 1989.
PRELIMINARY CASE STUDY 15
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L PRELIMINARY CASE STUDY 16 l-(
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,e For many SOVs, the MOPD rating does not appear on the nameplate or in the installation and maintenance instructions.
Vendor catalogs need to be consulted to determine those SOVs' 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 (Ref. 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 S0Vs exists, which could prevent the S0Vs from performing their safety-related functions.
At some plants, the task of verifying the potential for overpressurizing S0Vs 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 SOV overpressurization assumed the properoperationofin-linepressureregulators,itdid-notaddresstheconse-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 S0V 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 riepressurized.
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 M0PD, causing the 50V 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).
Informatico Notice 80-40 (Ref. 30) indicated that two-stage SRVs with Target Rock SOVs are susceptible to such M0PD malfunctions, whereas older three-stage SRVs having ASCO or AVC S0Vs are not.
Bulletin 80-25 (Ref. 31) required 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 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
- Telephone discussion between L. Kluit, Florida Power Corporation, and H. L.
Ornstein, USNRC, October 10, 1989.
PRELIMINARY CASE STUDY 17
l L
'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 w*
to replace the S0Vs with others having higher MOPD ratings.
In Nove@ er 1987, the Kewaunee plant actually experienced two SOV 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-zation (Ref. 25)
In the case of TMI-1, (Ref 32) the SOVs were connected to line pressures in-excess of the ;aaximum dictated by the 50Vs' M0PD.
In the case of Kewaunee and Calvert Cliffs 1 and 2, it was found that failure of a non qualified pressure 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 S0Vs 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)
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) 8 main steam isolation valves could have failed to perform their safety 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 50V 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
.. m (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 19,1968; (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)
I 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.
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."
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
a.
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 i
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. 41), the manufacturer has been aware of this problem at nuclear plants since 1978.
However in the late 1970s time-frame, c
Target Rock developed an SOV for use as a bi-directional isolation valve (would not open spuriously due to high backpressures).
Target Rock considered the spurious seat lifting to be an Architect Engineer / Licensee " application problem"
--not an 50V 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 L
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 lif t 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 50V 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)
(3 SOVs) & (10 S0Vs)
Harris 1 (1987)
(2 SOVs)
Hatch 2 (1988)
(12 SOVs)
The licensees' corrective actions were to re-orient the S0Vs to assure 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 l
.4-5.1.4.1 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 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 wou'id 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 de accumulators in the control building (in 3.7 minutes)pletion of 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 conditions to prevent removal of heat through the ultimate heat sink.
(3) Two uni-directional S0Vs were found in the instrument air system which could spuriously open upon loss of instrument air.
plant'pening would prevent long-term operability of all of the Such o s (16) ADS /SRVs.
.In Reference 42, the licensee also noted that several years earlier (1986) it had found three other Target Rock SOVs which had to be re-oriented due to spurious opening which was discovered when they were subjected to leak rate l
testing.
I-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-l tion, and lubricatior are described below.
Based on this experience, findings l
and recommendations relevant to maintenance problems are provided in Sections 7.2 and 9.2 respectively.
PRELIMINARY CASE STUDY 21 m -
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 licensees 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.
After the reactor scrammed in September 1985, the control room operators attempted to reset the reactor protection system (RPS).
RPS 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 pressure.
The reduced air header pressure (38 psig) was sufficient to allow the SDV vent and drain valves to cpen (opening pressure s8 to 15 psig), but it was not sufficient to enable the scram inlet and outlet valves to reclose (s42 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 S0Vs 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 diaphragms.
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 scram 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 1 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 leakage 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.
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.SOVs 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 manufacturer s control panel environmental qualification report.
6 Although the SOV manufacturer has stated that SOV failures have occurred because of incorrect use of lubricants on the Buna-N parts, the licensee was not provided with any such in,structions 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.
8 We are uncertain about the vulnerability of other 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 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 times 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 l
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 8 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-coil NP8323 SOV, controlling the inboard B MSIV, frailed to change state when it was de-energized.
Examination of the failed S0V 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 S0V's rebuilding process subsequent to the November 3, 1987 failure l
(Refs. 8, 9).
Apparently, during the original 50V rebuilding process, the licensee did not completely disassemble the ASCO dual-coil NP8323 S0V.
As a result, one or more small particles remained in the valve and remained undetected until it (they) caused the S0V'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 S0Vs will either be replaced with new valves or undergo complete disassembly and cleanout to ensure that no particles 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 operi 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 SOV, and that the particle broke up during subsequent S0V operation.
PRELIMINARY CASE STUDY 25
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 Loctito 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 SOV 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 that the Target Rock field service representative had done SOV 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 procedure cautions against application of excessive amounts of the adhesive.
The licensee concluded that the 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 SOVs were found to malfunction, two other ADS S0Vs 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
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 insertion time during a reactor scram (Refs. 54, 55).
The sluggish control J
rod insertion was attributed to the failure of an SOV* 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 rod did not insert within the technical specification allowable time of 7 sea nds.
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
- inserting control rods revealed that one valve of each pair had a yellow varnish-I 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 Loctite 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 L. sed in the rebuilding process.
It had appeared to be fully cured and the excess had not toen wiped off. When the system returned to service, the Loctite 242 migrated and hardened and bonded the 50V'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-L mentary service information letter, SIL 128 (Ref. 57) which recommended that all BWR owners discontinue using Loctite 242 or any other chemical adnesive thread lockers on the acorn nut of the pilot S0Vs.
GE had originally recommended using Loctite 242 to overcome loosening of the " acorn nut", 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 es
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 simulteneous failure was compounded by the fact that the licensee had rebuilt all 370 control rod scram S0Vs 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 S0Vs 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 internal 0-rings on the SOVs also were found to be degraded; they were brittle, 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 50V 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 cnd fill the 50Vs' exhaust ports, which blocked the discharge of air in the air actuator and increased the frictional force opposing S0V core movement.
The instrument air system was believed to have been the source of the hydrocarbon contamination.
Because of the susceptibility of the S0Vs' EPDM parts to hydrocarbon contamination, the licensee replaced all of the S0Vs with the same model 50V 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 1 and 2 instrument air systems (Refs. 61-64).* The licensee quickly recognized that the service water intrusion affected S0Vs 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
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 operating at 100 percent power.
The licensee's immediate response to the event 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 "t." 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 water that remained in the low points of the instrument air system and the mois-i
_ture and contaminants in the instrument air system resulted in widespread 50V
. 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 fifty Fisher control valve (ASCO S0V) failures.
It appears that those failures resulted from poor quality air due to the April 24, 1987 water intrusion event and from poor l
maintenance of the instrument air system.
1 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.
As a result of such practices, repetitive malfunctions were observed, the mal-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 S0Vs was cited in Reference 61 as l
follows:
l l
"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 lic~ensee."
Some of the systems that were affected by malfunctioning ASCO S0Vs (freestanding or piece parts of Fisher control valves) due to contamination of the instrument air system are listed in Table 2.
I PRELIMINARY CASE STUDY 29
Table.2 Systems Impacted At North Anna By SOV/ Control Valve Failures Due to Service Water Intrusion / Instrument Air Contamination Unit 1 and Unit 2 Residual Heat Removal / Low Pressure Safety Injection Main Steam Relief (PORVs)
Auxiliary Feedwater Ccmponent 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 S0Vs 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, sediment or other contaminants, and' cleaned accordingly
- A meeting was held at NRC Region II offices on Februarv 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 S0Vs, 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 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 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-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
i Lhad occurred at Unit 2 on April'24, 1987, before removing the service water from 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 S0Vs 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 The Susquehanna plants have experienced common-mode failures of S0Vs that resulted in multiple failures of control rods to insert, slow insertion of multi-pie control rods, and repetitive failures of scram discharge volume vent and drain valves.
The SOV failures were linked to contaminants in the instrument air system (i.e., hydrocarbons, 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 actuate both units' backup scram valves.
The backup scram valves are intended to provide 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 SOV 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 S0V failures are described below:
l On October 6, 1984, while Susquehanna I was operating at 60 percent power,
'two control rods failed to insert during individual rod scram testing.
Further l
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 SOV 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 SOV 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 S0V.
Many other BWRs' control rods are piloted by other model ASCO S0Vs, but two per control rod.
The ASCO S0Vs 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 and 2 control rods and all the backup scram valves.
About half of the SOV discs 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 1 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 j
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 i
caused a reduction in "the required ' extremely high probability' of shutting down the reactor in the ovent of an anticipated operational occurrence" (Ref 70).
l 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 S0V 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.
They were normally open, normally energized, and were designed to close (fail safe) on loss of instrument air or electrical power.
The failures of the S0Vs to
- The 50V 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
shift position upon de-energization were attributed to an amber-colored residue
. inside the SOVs. -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 in d led at the same time as the ones that failed, but were operated in the de-energized mode.
The de-energized SOVs had performed satisfactorily.
4 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 SOV 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 lubrient 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 slip'periness" for assembling rubber parts, and that it is absorbed into the rubber leaving no residue or harmful effect on the rub-ber." Subsequent to-S0V assembly (using the P-80 lubricant), the SOVs were cleaned however, minute amounts of the P-80 lubricant remained within the inter-nalcavItiesofthe50V.
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 S0Vs.
ASCO has discontinued using P-80 in the
. assembly of S0Vs as a result of the investigation.
On October 18, 1988, ASCO issued a 10 CFR Part 21 notification regarding the potential failures of NP8314 S0Vs (Ref. 73).
The notification accounted for 231 suspect S0Vs 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 @ 2 (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 S0Vs.
Fort Calhoun experienced.a similar failure of another energized NP8314 S0V 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 continuoesly energized service for 18 months to FRC for use in an PRELIMINARY CASE STUDY 33 W
Ju eL..
.w m.
.-*-.+a ee.
e.
i NRC sponsored 50V 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 50Vagingproram{thoseSOVswerealsolistedinASCO's10CFRPart21notifica-tion).
Six o FRC s purchased SOVs. waich were under aging failed prematurely (failure to shift position) going accelerated thermal as a result of organic deposits ("stickysubstance").
Af te' the deposits were " cleaned away" with acetone and the SOVs were reassembird, 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 )ursued by FRC because of budgetary restraints of the program.
In the course of tie FRC's 50V 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 tofacilitatetheassemblyofitstwostagesafetyreliefvalves(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.
0AG-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 facilityfNovember1988)that,parallelingtheuseofP-80atASCO,TargetRock had used mineral oils" to facilitate 50V assembly.
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 common-mode failures of EDG starting air system inlet valves (Refs. 78,79,80).
The 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 have a solenoid pilot valve that is normally closed and requires de power to actuate the solenoid pilot to admit starting air into the EDG.
The licensee has re)orted five ist6nces of common-mode failure of these valves.
The valves stuc( open when a sticky, slimy substance formed inside the poppet portion of the valve.
The licensee determined that the substance was the silicone lubricant Dow Corning 111 that was used on the valvas.
On five occa-sions the licensee cleaned the valves and replaced the Dow Corning 111 with Vase 1Inepetroleumjelly, Calcon's recommended lubricant is GE Silicone fluid G-322-L, which is significantly different from 00W Corning 111.
The licensee PRELIMINARY CASE STUDY 34
o.
did not check for the compatibility of Vaseline petroleum jelly with the Runa-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 deciccant).
Subsequently, the licensee upgraded its maintenance on the air dryers, thereby lowering the starting air moisture content.
In addition, the licensee cleanedthevalvesandreplacedtheVaselinepetroleumjellywithDowCorning 111 lubricant.
Theseactionsinconjunctionwithmorefrequentchahgeoutof the Calcon gas valve's elastomeric parts in accordance with the Delaval owners' grov) plant specific recommendations appear to have eliminated the valve sticdng problem.
5.2.4.3 Common-Mode Failure of 16 MSIVs at a Two Unit Station (BWRs):
Incorrect Lubrication In July 1986, the licensee of a two-unit station reporteo excessive stroke time of the Unit 1 "C" outboard MSIV which resulted from a failure of an Auto-matic Valve Corporation (AVC) 50V (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 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 degraded and they also leaked.
The original "a proved" or " preferred" SOV lubricant (based upon equipment qualification testin ) was Parker Su)er-0-lube.
However, later equipment quali-fication testing (19 5) found that tie Parker Super-0-lube could cause SOVs in the MSIV air pack to malfunction.
The Parker Super-0-lube was found to break 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 50V lubricant to E. F. Houghton SAFE 620.
In separate telephone conversations the SOV manufacturer (AVC) told the AEOD staff that it had informed the utility that E. F. Houghton SAFE 620 PRELIMINARY CASE STUDY 35
lubricant attacks and degrades the aluminum in the AVC valves.* Nonetheless, in accordance with utility purchase orders, AVC shi E. F. Houghton SAFE 620 to two different utilities.pped SOVs lubricated with 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 concluded 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 AEOD 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 before 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 Holykote 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 SSM would be more suscepti-ble to dryout.*** Because of these differences, it is not clear that Holykote 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 SOV several years earlier.
In that case, the sticking was attributed to not having onough 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) - Lubricant Suspected 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-i j
face (see Figure 1).
The SOV malfunctions impaired or prevented the MSIVs from l
closing within the times specified in the plant safety analyses, l
- Telephone discussions between T. Hutchins, Automatic Valve Corporation (AVC) l and USNRC (S. Israel - October 14, 1988 and H. L. Ornstein - April 12,1989).
l
- 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 Holykote 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
In the case of LaSalle, it was demonstrated that the cohesive / adhesive force i
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 p1'ig nut let go, the adhesive forces from the foreign substance between the two surfaces were able to supprt the weight of the plug nut to prevent it from filling."
Because the licensee suspected the Dow Corning 550 lubricant (applied to the SOVs internals at the factory) to be the cause of the sticking, the 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 they 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-torycoatedlubricant(Dow-Corning 550)fromtheIrinternalmetallicparts.
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 t
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, i
.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 licensee's corrective l
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, the licensee had performed a similar demonstration.
The sticky sub-stance at WNP2 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 l
- g Table 3 MSIV Air Pack 50V Failures (ASCO Dual-Coil 8323)
.?
25 Other SOVs Having g
Description Number of Foreign Unidenti-4 Plant / Event of 50V and Stuck SCVs fied Sticky Date Corrective Action and Location Substance (FUSS)
Comments g
N Grand Gulf 1 ASCO HTX8323* (Viton).
2 outboard All others (5)
In subsequent testing at ASCO 2/10/85 Replaced all 8 SOVs with lines (A and only 1 of 4 additional valves g
ASCO NP3323 (having EPDM C) I 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 liaes (B and inboard 50V inspected. Some are being like - attempted to re-C) (1 in-inspected was held for archival purposes.
nove the factory coated spected, FUSS found to have lubricant (Dow Corning.
fourd)
FUSS.
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.
g 6
~
s
~
- g Table 3 MSIV Air Pack 50V Failures (ASCO Dual-Coil 8323) (continued)
?
-3 Other SOVs Having Description Number of Foreign Unidenti-Q Plant / Event of 50V and Stuck SOVs fied Sticky Date Corrective Action and Location Substance (FUSS)
Comments c,
R River Bend ASCO NP8323 (EPDM) 2 outboard 1 other 50V was Licensee believes FUSS from m
12/1/89 Replaced all NP8323's lines (A and inspected (in-was from excessive application g
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 t!we 9/30/88 failures.*
1
- Telephone discussion between V. Bacanskas, River Bend, and H. L. Ornstein, USNRC, December 12, 1989.
1
The inspect. ion of the SOVs on the inboard and outboard MSIV air packs at all three planto 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 compromisirg 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 *,ests on the 8323 SOVs which had been replaced. There are no simple explanation.) for these failures individually or as a group.
The source (s) of the sti ny substance (s) which resulted in multiple 50V failures is uncertain.
There is major disagreement between the utilities, the 50V manufacturer, the reactor manufacturer and the laboratories regarding the root causes of the failures.
Internal 50V lubrication (by the manufacturer and in one case by the licensee), and poor air quality are primary suspects.*
5.3 Surveillance Testina 5.3.1 Control Rod Timing Tests - Failed Scram Pilot SOVs - Perry 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,
have been traced to an assembly error during manufacture.
Conceivably, a similar error may have been introduced during the assembly of the 8323 SOVs (see Section 5.2.4.1).
PRELIMINARY CASE STUDY 40
~
A
through March 28, 1988, and in each case the failures involved excessive air leakage.
Four of the five failures of the same valve (OA-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 SOV was rebuilt (core and spring were replaced).
The 50V's second failure was attributed to " wear of the core and spring assem-bly." The SOV was rebuilt again (core and spring assembly were replaced). The third malfunction of the same SOV 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 SOV was again found to be leaking air.
This fourth f ailure 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-238) 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, i
l PRELIMINARY CASE STUDY 41 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 SOV 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 cor,,binations of common-mode 50V failures.
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 S0Vs (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 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);
PRELIMINARY CASE STUDY 42
~
incorrect electric current (de vs. ac) (e.g., Appendix A);
inadequate terminal or iunction box connections as a result of inade-quate manufacturer's gu;tdance or architect engineer's interpretation of manufacturer's guidance (e.g., Appendix A).
(4) Manufacturing Defects Lubricationerrors(e.g.,Section5.2.4.1);
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 SOV failures are documented.
In many cases SOVs are viewed as expendable items, installed without any failure reports.and their failures are simply view replacements are (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.
(3) Many SOVs that are subcomponents or piece-parts of other larger components or systems are not always reported as SOV failures in the nuclear plant reliability data system (NPRDS) for example, MSIVs, flow regulators, gov-ernors that fail to function properly because the related S0Vs have failed are unlikely to be reported as 50V failures.
Hence, an accurate estimate of SOV 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 t. rude estimate of SOV failure rates.
Nonetheless, Table 4 lists SOV 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.
It is significant that assuming quarterly te. ting 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 NPRDS failure records used for estimating SOV failure rates generally do not include the unrecognized S0Vs, 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
Table 4 Estimates of 50V Failures to Operate Estimated Source failure rate WASH 1400 1x10 8/ demand This study 7 to 9.5x10 8/ demand (NPRDS data Jan 85-Dec. 88)
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 3/ demand (Grand Gulf PRA) l NUREG/CR 4819, Vol. 1 7x10 8/hr 4
(NPRDS data Sept 78-July 84)
This study 6.4 to 8.7x10 6/hr (NPRDS data Jan 85-Dec. 88)
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, Such an undertaking is beyond the scope of the present study.
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 towardt 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 50V maintenance requirements.
Theneglectoroversightof SOV maintenance oftentimes comes from the 50V 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.
PRELIMINARY CASE STUDY 44
i Examples of the variation among SOV manufacturers' maintenance recommenda-tions are discussed below.
ASCO does not provide any specific recommendations for 50V maintenance or refur-LTsiment. This is even true for their nuclear qualified 1E valves. Quoting ASCO's installation and maintenance bulletin for NP8323 SOVs (Ref. 92).
" Preventive Maintenance 1.
Keep the medium flowing through the valve as free from dirt and forei n material as possible.
Use instrument quality air, o 1-free for Suffix "E."
2.
While in service, operate valve periodically to insure proper opening and closing.
Periodic ins l
3.
conditions) pection (depending upon medium and service of internal valve parts for damage or exces-sive wear is recommended. Thoroughly clean all parts.
Replace any parts that are worn or damaged.
4.
The valves may require periodic replacement of the coils and all resilient parts during their installed life to maintain qualification.
The exact replacement period will depend on ambient and service conditions.
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 T 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 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.
Circle Seal, Ross and an Unspecified Foreion 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 recommendations.
Lack of specific maintenance recommendations has contributed 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 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 foe BWR recirculation pumps and main turbine-trip systems are not provided with preventive maintenance or refurbishment recommendations.
PRELIMINARY CASE STUDY 45
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1 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 notidentifythecareregulredbytheSOVwhichis" unrecognized"withinthe "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.
BWRhighpressurecoolinginjectionsystems:
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).
During a trip to the Duane Arnold plant in reviewing SOV experience, AEOD staff learned that subsequent to the July 1982 failure (Ref. 98), the Dt.:ne Arnold staff recognized the SOV's limited lifetime and the need for SOV refurbishment or replacement.
As a result the Duane Arnold staff added SOV changeout to their preventive maintenance program.
However, several years later, plant maintenance personnel made a decision to eliminate changeout of that 50V from their preventive maintenance program.
The rationale for dropping such pre-ventive maintenance was that the SOV 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 S0Vs 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
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-utes.
As a result, the licensee initiated a program for repairing and replacing the SOVs and control valves, as well as upgrading the air system quality and enhancing plant personnel training and maintenance practices.
6.3.2.3 UnrecognizedSOVsinBWRHighPressureCoolantInjectionSystems In Reference 99 the Duane Arnold plant's licensee reported the failure of the remote shutoff control system which is part of the HPCI turbine's governor system.
Discussion with plant personnel and the turbine manufacturer indicated a lack of communication between t1em 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 SOV.
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 50V 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 50V preventive maintenance, or service life.
The service information 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 SOVs are not addressed in any of GE's SILS.
6.3.2.4 Unrecognized SOVs in Instrument Air Driers Review of a leading instrument air drier manufacturer's operation and nintenance manual indicated minimal guidance with regard to SOV maintenance.
The 50V: 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 SOVs 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 50V failure reports and follow up discussions with plant personnel NRC inspectors, and SOV manufacturers showed that shortcomings in many utillties' 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.
PRELIMINARY CASE STUDY 47
1 (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 plant personnel revealed that subsequent
)
to rebuilditg the SOV, plant personnel bench tested the 50V with poor qual-ity service air instead of clean, dry instrument air.
Inspection of the SOV revealed that oil from the service air system had caused the SOV's second failure.*
(4) The Calvert Clin's 1 and 2 plants' SOV maintenance is tracked by the sta-i tion's reliability centered maintenance (RCM) program.
The RCH program 1
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 SOVs has been a significant cause of SOV failures.
There is a broad range of com-plexity associated with rebuilding SOVs, depending upon individual 50V manufac-turer and model number.
To further coniplicate 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 testfixtureforlicenseestotesttheIrrebuiltSOVs.
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.
SeriousquestIons i
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-l.
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. 00 Trne, Baltimore Gas and Electric Co., and H. L.
Ornstein, USNRC, April 21,.889.
PRELIMINARY CASE STUDY 48 l
{
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 by the elastomeric parts, attention should be focused on the shelf life and on tM 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 partsberebulltperiodicelly.
The fre uency of rebuilding should be governed by 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 being from the time of kit manufacture (not from the time of rebuild).
PRELIMINARY CASE STUDY 49
7.0 FINDINGS The root causes of most 50V 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 cases, the manufacturers have not provided the end users with a full understanding of the sensitive nature of certain parts of the SOVs.
Many users have learned after using certain SOVs that they are unforgiving and finicky with regard to contaminants and local environmental conditions.
Deficiencies in selection, operation, and maintenance of SOVs have resulted in hundreds of SOV failures, many of which were common-mode failures that cut 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 Temperatures Many common-mode 50V failures have resulted from sub temperatures in excess of their original design envelope.jecting SOVs to ambient Such common-mode l
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 l
allowed to p' seemingly" premature failures.revail for extended time periods with sustaining 7.1.2 Heatup from Energization Many common-mode SOV failures have occurred because the estimated service l
lives did not properly include the life-shortening effects of heatup due to l
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 heatt'o 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 P
Many licensees have found misapplications in which S0Vs could be or were subjected to operating pressure differentials that could or did prevent them PRELIMINARY CASE STUDY 50 l
l
~
)
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 i
have addressed the issue, of over-pressure which could result from pressure regulator failures.
7.1.4 Unrecognized SOVs Used as Piece-Parts Many SOVs 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 50V 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 reco nize or were not aware of the directional requirements of the valves (see Sect.on 5.1.4.1).
In addition to reports of SOV malfunctions which occurred because l
they were installed backwards, there are also reports of SOVs which were installed upside down, or at improper angles (see Appendix A).
7.2 Maintenance Operating experience has confirmed that SOV maintenance deficiencies can incapacitate multiple safety systems.
The pervasiveness of maintenance defi-ciencies highlight the need for implementing aggressive SOV maintenance pro-grams to prevent widespread common-mode failures.
Specific maintenance problem areas are discussed below.
7.2.1 Maintenance Frequency l
l Lack of timely preventive maintenance (complete SOV replacement or rebuilding i
of short-lived piece parts of S0Vs) has resulted in many SOV failures (see Sec-tions 5.1.2.1, 5.2.1.2 6 theuserswithdefinitIve.3.2.1).
Many SOV manufacturers have failed to provide l
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 amung manufacturers with regard to specifying (or not specifying) the allowablo 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 elastomeric 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
7.2.2 Replacement Versus Rebuilding Rebuilding or refurbishing certain models of several manufacturers' SOVs is 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 reinstallation 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 SOVs correctly is the fact that many manufacturers do not provide the licensees with adequate SOV 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 SOV manuf acture (see Section 6.3.4).
Discussions with plant personnel have revealed that many licensees, (e.g.,
Perry, River Bend, Salem, Grand Gulf, Quane Arnold) have chosen to discontinue rebuilding certain SOVs because improper rebuilding can result /has resulted in many SOV 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 SOVs (Ref. 106,107).
ASCO's decision to discon-tinue supplying 50V 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 50V failures have been caused by contaminants in the fluids which flow through SOVs; instrument air in particular (see Sections 5.2.3.1, 5.2.3.2,5.2.3.3).
SOV contamination resulting from particulates, moisture, and hydmcarbons
~
in the instrument air system have been a major source of common-mode 50V 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 50V failures are clearly attributed to subjecting the SOVs 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.
PRELIMINARY CASE STUDY 52
7.2.4 Lubrication Improper lubrication has resulted in many common-mode 50V 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 Several cases (see Section 6.3.3) have been reported in which SOVs 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 operators to operate a BWR with multiple failed scram pilot SOVs.
7.4 Verification of the Use of Qualified SOVs The issue of environmental qualification of Clus 1E electrical equipatM 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 are being used in safety-related applications without appropriate verification of product quality and design control.
In many instances tne SOVs lack verifia 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 IE 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 SOVs (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 SOV 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 50V malfunctions.
PRELIMINARY CASE STUOY 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 50V failures cannot be found, or cannot be eliminated, the need for 50V diversity (with regard to model, energization mode, failure mode, or manufacturer) becomes apparent.
(See Appendix B for a discussion of an example of such a problem with the 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 19B8) 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 Centrols Dresser-Rand / Terry Turbine,XomoxValves,CaliforniaControls(Calcon), Colt /FaIrbanks-M;rse),it was found that SOV manufacturers have not been fully apprised by the utilities of many 50V 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 SOVs.
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).
l l
PRELIMINARY CASE STUDY 54 i
~ -. - -.
e
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 Consideringtheapplicationofthe"singlefailurecriterion,"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 comon-mode failures.
Operating experience shows that SOVs are vulnerable to numerous comon-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 comon-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 SOV failures or degradations highlights the gravity of the situation.
Although plant safety analyses do not address comon-mode, multi)1e train / multiple safety system failures, operating experience indicates that t1ey have occurred and continue to occur.
The comon-mode SOV 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 SOV 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.
PRELIMINARY CASE STUDY 55
i 8.2 Need for Action On the basis of our analysis of operating data, we conclude that the SOV 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 50V 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 needed now to address the root causes of 50V 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
Q 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 i
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 Desian Verification Licensees should review SOV design specifications and actual operating 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
.50V service life.
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 50Vs.
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 depend upon them.
l 9.2 Maintenance 9.2.1 Frequency Licensees should implement SOV maintenance programs to replace or refurbish SOVs on timely bases.
Replacement or refurbishment schedules should focus upon l
thermal aging due to elevated ambient conditions and heatup from continuous coil j
energization.
PRELIMINARY CASE STUDY 57
9.2.2 Replacement Versus Rebuilding
- Licensees should review their programs for rebuilding SOVs 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 SOVs.
9.2.3 Contamination Aggressive actions should be taken to assure that fluids which flow through SOVs, instrument air in particular, are maintained free of contaminants.
If operational experience indicates a pattern of SOV 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 (In accordance with Generic Letter 88-14).
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 ofsurveillancetestingIoningS0Vs. root cause failure analysis, and timely repair or replacement of malfunct Licensees should review, and if appropriate, modify their surveillance testing procedures.
Procedures should expressly prohibit " tapping" or mechanical agitation of SOVs as techniques to assist successful operation during surveil-lance testing.
Procedures should include actions to be taken when unsatisfactory 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 l
in service (even though subsequent retest results may be satisfactory).
9.4 Verification of the Use of Qualified SOVs Licensees should review all SOVs in safety-related applications, EDGs in particular, to ensure that they meet 10CFR 50 Part B and appropriate Class 1E requirements; and that they have been installed and maintained appropriately to assure they will operate in a manner consistent with the assum)tions of the plants' safety analyses.
If there is doubt regarding the accepta)ility of any such SOVs, they should be replaced with appropriately qualified ones.
- exclusive of coil replacement - coils are generally replacement items PRELIMINARY CASE STUDY 58
\\
9.5 Redundancy and Diversity When operating experience indicates unexplained repetitive common-mode SOV 1
failures affecting redundant components - (such as BWR MSIVs and containment isolation valves), licensees should consider performing maintenance, testing and j
replacement of redundant SOVs on a staggered basis.
Aoditional consideration should be given to using diverse SOVs (different design or manufacturer).
9.6 Feedback of Operatina Experience In order'to improve SOV reliability, an industry group such as the Institute of Nuclear Power Operations (INPO) should initiate an SOV failure feedback prog-ram.
The program should alert SOV manufacturers to failures of their equiament by providing them with complete failure records of their specific SOVs sue 1 as those found in NPRDS.
4 PRELIMINARY CASE STUDY 59
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, Volume 1.
Operating Experience and Failure Identification," Oak Ridge National Laboratory, NUREG/CR-4819, ORNL/Sub83-28915/4/V1, March 1987.
2.
CarolinaPower&LightCompanyIcPlantUnit2, February Licensee Event Report (LER) 50-324/88-001 Rev. 5, Brunswick Steam Electr 19, 1990.
3.
Burns and Roe, " Investigation of Valve Failure Problems in LWR Power 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 1,19M *,o 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, Inspaction Report 50-440/87-024, Perry Nuclear Power Plant Unit 1, January 22, 1983.
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 Nember 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 Temperaturo 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
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 Regulatorv Comission, Information Notice 89-66, "Qualifica-tion Life of Solenoid Valves," September 11, 1989.
' 9.
Automatic Switch Company (ASCO), " Field Notification Concerning the Qualified Life of ASCO Catalog NP-1 Valves," October 27, 1989.
20.
Memorandum, P. T. Knutsen, Virginia Electric and Power Company, "Self Heating Effects in ASCO Solenoid Valves," dated February 3, 1987.
21.
North 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 Commission 10 CFR 50.72 Report Number 12015, i
Calvert Cliffs 1 and 2, April 14, 1988.
27.
U.S. Nuclear Regulatory Commission, Inspection Report 50-317/88-07 and l
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 Cor) oration, Licensee Event Report (LER) 50-302/89-01 Rev.
2, Crystal River Jnit 3, June 7,1989.
30.
U.S. Nuclear Regulatory Commission, Information Notice 80-40, " Excessive Nitrogen Supply Actuates Safety-Relief Valve Operation to Cause Reactor Depressurization," November 7, 1980.
31.
U.S. Nuclear Regulatory Commission, 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
32.
Metropolitan Edison Co., Licensee Event Report-(LER) 50-289/80-018. Three Mile Island Unit 1, November 4, 1980.
-33.
Georgia Power Com m y, 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,
_F Crystal River Unit 3, January 7,1989.
4v.
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, Ge vic Letter 88-14, " Instrument Air g
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,
-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, Dresden Nuclear Power Station, Unit 3, October 1,1985.
m 98.
U.S. Nuclear Regulatory Commission, Office of Inspection and Enforcement, t
Information Notice No 85-95,'" Leak of Reactor Water to Reactor Building 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. AE0D/C403, "Edwin I. Hatch Unit No. 2 Plant Systems Interaction Event on August 25, 1982," May 1984.
PRELIMINARY CASE STUDY 62
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 Comission, 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. Nucleur Regulatory Comission, 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 ',
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 Comission,
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 Comission, " Report to Congress on Abnormal Occurrences, October-December 1985," NUREG-0090, Vol. 8, No. 4, May 198L.
61.
North Anna Station Deviation Report,87-379, April 24, 1987.
-62.
U.S. Nuclear Regulatory Comission, 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) 50-338/8s-002, North Anna Unit 1, February 7, 1989.
64.
North Anna Power Stetion, memorandum, " Water Intrusion Into Instrument Air System Event - 1,pril 1987," by T. L. Porter, August 8, 1988.
PRELIMINARY CASE STUDY 63
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 Commission, Region II, " Notice of Significant Meeting," February 2, 1989.
68.
U.S. Nuclear Regulatory Commission, Inspection Report No. 50-387/84-35; 50-388/84-44, Susquehanna Steam Electric Station, November 15, 1984.
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 Commission, Inspection Report 99900369/88-01, Automatic Switch Company, August 30, 1988.
~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.
)
80.
U.S. Nuclear Regulatory Commission, Inspection Report 50-413/89-07 and 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, i
U.S. Nuclear Regulatory Commission Region III, December 19, 1986.
1 i
l' PRELIMINARY CASE STUDY 64 l
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.
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-F0280," prepared by Sargent & Lundy, January 14, 1988.
85.
U.S. Nuclear Regulatory Commission, Inspection Report 50-373/87-035, LaSalle County Station, Unit 1, January 1988.
l 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.
88.
Gulf States Utilities Co., River Bend Station, " Analysis of Components in an ASCO Solenoid Valve," Franklin Research Center Report, P-741-1, l
February 9, 1989.
89.
U.S. Nuclear Regulatory Cownission 10 CFR 50.72 Report Number 17201, November 27, 1989.
90.
U.S. Nuclear Regulatory Commission Region III Daily Report, 1
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), Ir sta11ation 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 Repert, 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/
82-039, 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. Shook, V. P. Bacanskas, S. Carfagno, " Equipment Qual -
ification Research Test Program and failure Analysis of Class IE 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-1 l
I f
PRELIMINARY CASE STUDY 66
.e
,i
~\\-
1 l
l APPENDIX A-50V FAILURES REPORTED IN LERs, 1984-1989 I
3
., " ":;. s
~'-
hi 1
Legend for Appendix A 000 NO. = Docket Number REP FL = Repetitive Failure
.TP/0VT = Cause Reactor Trip or Plant Outage FC
= Failure Category 1
I l
l l
l i-I
+
v
.0 APPENDIX A FAILURE CATEGORIES OTHER 00 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 l
EXCESSIVE ENVIRONMENT TEMPERATURE 10 i
l MOISTURE INTRUSION (ELECTRICAL SHORTS / GROUNDING /0 PEN CIRCUITS) 11 CONTAMINANTS (DIRT, WATER, RUST, HYDMCARBONS, DESICCANTS, etc.)
12 MOPD (MAXIMUM OPERATING PRESSURE DIFFERENCE) 13 DESIGN ERROR (OTHER'THAN M0PD) 14 l
EQUIPMENT. QUALIFICATION-SEISMIC 15 L
EQUIPMENT QUALIFICATION-RADIATION 16 l
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 LEAKAGE UNSPECIFIED 26 ASSEMBLY ERROR (PLUG / DIAPHRAGM / SPRING etc.)
27 EQUIPMENT QUALIFICATION (ELECTRICAL) 28
d Page No.
1 06/07/90 SOLENCID-OPERATED VALVE FAlltJRE DATA
~
DOC PLANT EVENT-LER NO. OF FAILED SYSTEM MAeNJFACT MODEL ROOT REP CORRECTIVE COISIENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER FAILtJRES PART NO.
CAUSE FL ACTION DOCUNENTS OUT -
206 San Onofre 1 12/30/86 86-014-01 One Ground Feedwater & Not Not Moisture in No New Jtnction Corrective LER 87-001 No 11
- fault, Safety Specified Specifi junction box box instatted action taken on moisture Injection ed failed jtnction in System box and seven junction other box vulnerable ones.
206 San Onofre 1 01/17/87 87-001 One Ground feedwater Inadequate Yes Eliminated Vibration No 07 fault instattation/v ground, tighten caused ibration ed connections loosening of terminal box conduit locking ring 2% San Onofre 1 11/10/87 87-016 Five failures of Slug Containment ASCO 206-380 Lubricant Yes Secured SOVs cause of Insp Rpt No 05 four valves sticking Isolation, suspected in safety sticking under 89-24 Contairunent position and investigation Spray initiated weekly testing 206 San Onofre 1 12/01/87 87-017 Two Not Safety Not Not (Jnknown No Repaired or SOY required None No 19 Specified injection Specified Specift replaced SOV for venting SIS vent ed to avoid water hanumer 206 San Onofre 1 12/16/87 87-018 One Ground Plant Not Not Loose screws Yes The ground was The loose See No 11 fault cooling Specified Specifi and inadequate eliminated by screws were consnents moisture water ed seat. Root removing the probably in SOV cause not water inside stripped from 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 Target 80EE-00 Still under Yes SOV was SOV failure LER No 19 sleeve-Injection Rock 1
investigation replaced.
prevented bleed 206/81-020 and Modifled off from double position maintenance disc gate valve indicatio procedures (ine bonnet.
n switch tuding inplementation of mir's reconsnend for new reed switch calibration
Page No.
2 06/07/90 SOLEN 0ID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE CopeqENTS REFERENCE TP/ FC No. NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACit0N DOCUMENTS OUT 206 San Onofre 1 03/03/89 89-008 Contalment Design error Design Discevered that.
14 -
fire modification a single SOV suppression made could degrade containment spray system,resultin g in containment overpressure during a LOCA 206 San Onofre 1 08/23/89 89-026 One Failed to Recirc ASCO 206-380 Suspect Yes Replaced Sov LER 87-016 No 05-
- shift, system tubricant
" sticking (safety stuga injection /co ntainment spray) 213 Haddam Neck 11/02/84 85-005 Two Failed to Auxiliary ASCO NP8320 Unknown No Sov retested Sovs failed None No 05 shift
. Feed 4:ter acceptably, during testing.
" stuck" System declared SOVs required operational, for more frequent auto-initiation cycting tests of AFW ptanned 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 shift,"st Feedwater Initiated more sticking has uck" System frequent not been periodic detemined.
cycling Game SOVs as in LER 85-005 213 Haddam Neck 01/14/88 88-001 Four incipients SOV Containment Not Not Design No Corrected Instatted SOVs None No 06 operating Isotation - Specified speciff Deficiency circuit close upon mode Steam ed design, rather deenergiring Generator than changing instead of Blowdown the SOVs.
opening upon deenergizing per design.
Condition existed for seven years m
G e
7
.a
~ ~. ~
s--n
Page No.
3 06/07/90
~
SOLENOID-OPERATED VALVE FAlttJRE DATA 1
(
DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE COMMENTS REFERENCE TP/ FC' NO.
NAME DATE NUMBER FAILtJRES PART NO.
CAUSE FL ACTION DOCUMENTS OUT 219 Oyster Creek
'10/16/84 84-022
~Three Diaphraga Scram -
Not Not Instatled No Instat1 Caused slow None No. 27 Discharge specified specifi diaphragm diaphram closure of 3 volume ed backwards, correctly and air-operated Inadequate SOV develop SDV vent and I
rebuilding and improved drain valves l
inadequate post-maintenan i
post-maintenan ce testing ce test 220 Nine Mile Pt 1 06/14/84 84-013 Three Seat Main steam Dresser /C 1525VM Wear and Yes 1 refurbished, Retest of att 6 LER 84-014 No 03 teakage(2 line onsot.
contaminants 2 replaced valves fomd
),misposi Electroma
- suspected' all to be tioned tic teaking due to wires matsrfal todged in the seat ares (see LER 84-014) 220 Nine Mile Pt 1 06/17/84 84-014 Six 5 seat Main steam Dresser / 1525 VM Foreign Yes Cleaned and Retest of att 6 84-013 No 12 teakage /
' Consot.
material refurbished SOVs (LER 1 stuck Etectroma intrusion SOVs84-013) found open due tic (source not att to be to stated) teaking due to foreign foreign matt fasterial todged in the seat area 220 Nine Mile Pt 1 11/01/85 85-021 One plus two Jansned Main steam Dresser /C 1525VM Wear Yes Replaced att None No 03' incipients springs onsot.
three valves Electror.a tic 237 Dresden 2 07/17/87 87-023 One
' Internal Feedwater ASCO 8300 Wear Yes Replaced SOV SOV is a None Yes 18 passagewa (FWRV) piecepart of the FWRV.
y restricti on 245 Mittstone 1 12/24/85 85-034-01 setween three 1 core Control rod Asco Not Deterioration Yes SOVs rebuilt, Failure of None No 17 and six
- spring, drive specifi of the Buna-N
@ graded SPSV three controt many ed disce and a maintenance rods to scram discs detached program per GE was attributed spring.
SIL 128 to falture of three to six associated scram pitot solenoid valves.
9
_.m.
y
~.. _,...
m
.g
Page No.
4 06/07/90 SOLENO!D-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE COMNENTS REFERENCE TP/ FC'.
No. NAME DATE NUMBER FAILURES PART.
NO.
CAUSE FL ACTION DOCUNENTS OUT 245 Mittstone 1 06/06/87 87-015-02 One Excessive Containment Target Not Plunger tthe No Replaced None None No ' 03.
tenkage isolation -~ Rock Speciff scored pitnger tube post ed accident sanpt ing 247 Indian Point 2 01/04/84 84-001 One Faited Containment ASCO Not Not Specified No Replaced SOV None Mone No 21 closed purge Specifi ed 247 Indian Point 2 11/27/84 84-022 Two Not AFW Steam Not Not Not Specified No Reconnected SOVs controt None No 09 Specified Specified'Specifi power leads to AFW turbine ed
.SOVs intet steam isolation valves 247 Indian Point 2 02/02/87 87-003-01 One Stuggish Condensate Not Not Design No Enterged SOV SOV controts None No 24 performan (storage specified Specifi deficiency orifice and ADV. Slow ce tank ed (sizing) cleaned closure isolation) regulator attributed to orifice size.
Debris could have also contributed.
249 Dresden 3 01/12/85 85-001 One Manual Main turbine Sperry FSDG454 Grease No Replaced SOV SOV controls None Yes 04.
operator Vickers 012A contaisination overspeed trip 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 contaiment Asco Not Not Specified No Replaced SOV LER250/84-No 03' Specified isolation specifi
. valve 09,020 (nitrogen ed l
stpply) 250 Turkey Point 3 12/13/84 84-034 One Not CVCS ASCO Not Yes Replaced SOV SOV controts See No 02 A0V. Ref.
Consnents specified (isolation Specifi valve) ed Documents: LER 250/84-032, 251/84-009,84-0 20 4
e O
r-'?"*
' ~ '
Page C:o.
5 06/07/90
~
SOLENOID-OPERATED VALVE FA! LURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE COMMENTS REFERENCE-TP/ FC No. NAME DATE NUMBER FAILURES PART
' NO.
CAUSE FL ACTION 00QMNTS ' 0UT -
250 Turkey Point 3 01/13/85 85-002 One Ctogged Not mot mot Not Specified No Cteened air similar mone No 17 SOV air Specified Specified Specifi fitters on occurrences:
filters ed this and other LER 250-84-034, similar SOVs LER 250-84-031, in both units LER 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 aeplaced 1 2 independent None Yes 09 -
~
Specified (MSIV) interference, SOV,' fuse SOV failures 1 bent contact block pins discovered pins at fuse were difring testing.
block.
straightened MSIV cout @ t on other SOV. be closed 250 Turkey Point 3 08/03/86 86-031 One Not Auxiliary /em ASCO 206-381 Water entering No Sov replaced simitar See Yes 03 specified ergency the SOV occurrences:
consment feedwater LER 251-84-020, and LER 251 *5-009 250 Turkey Point 3 01/03/87 87-002 One coil caponent ASCO 8316 Not Specified No Replaced SOV Nr.se No 01 Cooling Water 250 Turkey Point 3 09/13/87 87-023 One Internal Steam Target 300525-Faulty wires No Not Specifier' None None Yes 06 wiring Generator Rock 1
going to Reed Blowdown switch 251 Turkey Point 4 07/15/87 87-015-01 One Ground Containment Not Not Deterioration No Cleaned anc SOV is a mone No 18 fault Isolation Specified Specift of insulating retaped wit ing piece-part of (pressurizer ed tape from connections A0V sanpting}
% rmat ageing" 254 Ouad Cities 1 02/05/85 85-001 Two Connactio HPCI Barksdale 178250H Faulty Repair Failure of NPCI No 07 n to SOV C2D4 terminal terminal turbine tripand power connection and connections reset SOVs lead vibration and secure wires to SOV housing
Page No.
6 06/07/90 SOLENOID-OPERATED VALVE FAILURE DA1A DOC PLANT EVENT LER NO. OF FAILED SYSTEM MAuttFACT MODEL ROOT REP CORRECTIVE COMMENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DOCUMENTS OUT 254 ound Cities 1 04/03/87 87-006-01 One viring High Barksdale 1018433 Vibration /ined Yes Reptoced coils MPCI LER 85-001 No 07 -
connectio Pressure ACPI equate on failed SOV' inoperable.
n to coit Coolant connection /ina and three Replaced SOV Injection dequate others coils with support replaced at newer model, units 1 and 2 also added wiring restraint to att four SOVs.
255 Palisades 04/10/86 86-017-01 Three fali +
Valve Reactor Target 808-001 Metat shavings Yes Repaired SOVs
.Yes 12 three incipients seat Coolant -
Rock in valve seat and system teakage (head vent) area.
flushed to remove remaining metat shavings 255 Palisades 01/14/87 87-001-01 Eight Inadequat Containment Not Not AE design No Isolation None None No 14 isolation (hy Specified specifi error logic modified e
isolation drogen ed logic monitoring) 259 Browns Ferry 1 07/03/86 86-022 Six incipients ECCS Rockwell/
Design error Remove air Potentist for No 14 Atwood supply to overpressurI2in Morritt affected g low pressure actuator systems due to use of non qualified SOVs (six in each of three Browris Ferry inits) 260 Browns Ferry 2 08/31/87 87-007-01 Potential Loss of Containment Not Not Design error Yes Replace SOVs Use of None No 14 failures att 3 SOV Dryweti Specified Specifi with qualified non-qualified units function Control Air ed ones SOVs could prevent primary containment isolation. Att 3 Browns Ferry units affected.
A O
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4E Page No.
7 06/07/90 SOLEN 0!D-OPERATED VALVE FAILURE DATA i
[
l DOC PLANT EVENT LER No. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE COMMENTS' REFERENCE..TP/ FC NO.
NAME DATE-NUMBER FAILURES PART NO.
CAUSE FL ACTION DOCUMENTS OUT -
l l
260 Browns Ferry 2 06/06/89 89-018 One Valve Emergency Salem 812-6 Corrosion Yes Reptaced Sov Licensee No 12 seats dieset debris from tegraded EDG l
generator starting air air system and air start system performed maintenance on it prior to event but debris was believed to be there from before 261 H.B. Robinson 2 05/13/87 87-007 Two Not Not ASCO Not Inadequate Yes Instatt Incorrectly None No 16 Specified Specified Speciff instattations correct seats installed ed of conduit conduit seats seats at entrance to several harsh environment 1E qualified SOVs.
Potential for moisture intrusion 261 H.B. Robinson 2 07/15/87 87-020 One Electrica Feedwater Not Not Water trapped No Wire was SOV is None Yes 11 i short (FWRV) specified Specifi in 50V repaired and piece-part of ed condolet water removed FWRV from the condutet.
Other Sovs examined for simiter problems.
261 H.S. Robinson 2 11/05/87 87-028-01 Two Sov Dieset Not Not Internal waar No Replaced SOVs Sov failures None No 18 internals Generator Specified Specifi caused venting Starting Air ed of starting air 263 Monticetto 10/25/89 89-032 One
' Loose Main steam Tighten.
No 09 terminat (MSIV) terminal screw screw and inspect simitar Sovs
4 Page No.
8 06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAfLED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE CopWEENTS REFERENCE TP/ FC NO.
NAME DAtE NUMBER FAILURES PART NO.
CAUSE FL ACTION 00QMENTS OUT 265 ound Cities 2 06/28/85 85-015 One mot Reactor Versa See Not Specified No Sov replaced VGS-4422-U-10-3 None No 20 1-38C specified 8tdg. Vent.
consnent System 265 ouad Cities 2 02/18/87 87-004 One Not containment ASCO 8317
- Solenoid Replaced Sov SOV is No 21 rusted and piece-part of specified vacuum vacuum breaker corroded" (reason / source air test not stated) cylinder 265 ound Cities 2 09/18/87 87-012 One plus two Not Containment ASCO 8317 Unknown Yes Not Specified SOV is LER 87-004 No 20 piece-part of incipients spectfled Vacuum vacuum breaker Relief air test cylinder 265 ound Cities 2 12/10/87 87-020 One Not Main Turbine Sperry F3-SDG4 Not Specified No Rptated SOV None' None Yes 02 Specified Control Vickers 54-0124 Fluid No Rebuilt SOV Failed SUV LER 87-020 Yes 21' 265 cuad Cities 2 04/06/89 89-001 One Turboganerat controts or turbine master trip solenoid No 21 266 Point Beach 1 06/0i/89 89-003 One Containinent ASCO 8302 Replace SOV isolation (SG blowdown sampting) 271 Vermont Yankee 08/18/87 87-009-01 Mot Specified Seat Automatic ASCO 206-381 Dirt / corrosion Yes Sov cycled None None No 12 teakage Depressurire products from tion the air smply 272 Salem 1 12/31/84 84-029 One faulty Feedwater ASCO Wot Not Specified Yes Replaced SOV SOV is a Mone Yes 09 electrica (FnWtV)
Specifi piece-pert of FWRV
(
ed connectio n and seat 272 Setem 1 01/31/86 86-003 One Seat Feedwater ASCO Not Probably Yes Two SOVs were SOV is a Mone Yes 12 testage teakage (FW2V)
Specifi contaminated replaced piece-part of ed air the FWRY. Dirt and moisture were detected in air lines causing other associated faitures 6
O O
e
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^
l Page No.
9 06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA i
l DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEt.
ROOT REP CORRECTIVE ComENTS REFERENCE TP/ FC l
NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACit0N DOCLMENTS OUF i
2 72 Salem 1 02/20/86 86-006 One Broken Feedwater Not Not Instattation No Reptoced wire None None Yes 07 wire (FURV) specified Specifi error and and checked ed vibration similar SOVs 272 Salem 1 04/G8/86 86-007 Eighteen Electrica Post Not Not Design /instatt No Instatt 18 SOVs on None No if.
incipients t
accident Specified Specifi ation required units 1 aws 2 connector sampling ed error,inadequa connectors had inadequate s
te comectors l
instattation procedures 275 Diablo Canyon 1 01/02/85 85-001 Two SOV Main turbine Not Not Not Specifier! No Replaced SOV None Yes 21
" stuck (overspeed Specified Speciff open" protection) ed 275 Diablo Canyon 1 07/24/87 87-011 None Containment Not Not Procedura?
No Perform Failure to None No 22 i
isolation Specified Specifi inadequacies necessary verify ed verification. penetration Upgrade isolation procedures subsequent to SOV replacement.
277 Peach Bottom 2 04/27/84 84-008 One Not Containment Asco 8320 Not specified No Replaced SOV Potential None No 19 Specified Isotation existed for e (SBGT) single failure to have prevented the fulfilment of the safety function of the
$8GT system 277 Peach Bottom 2 01/24/86 86-003 Two DC coits Main Steam Autsnatic Not Under No The falted DC Falture of 2 DC None Yes 19 (MS!v)
Val e specifi investigation solenoids were SOVs in 2 Conoany ed replaced.
separate lines (AV:)
caused ctOsure of MSIVs 277 Peach Bottom 2 05/29/87 87-008 Three Control room Piping No Reconnected SanDie lines to No 20 ventitation/
configuration tubing to SOVs three SUVs had radiation error property been connected monitoring incorrectly.
Affected contret rooms at both units 2 and 3
i.
l Page No.
10 l
06/07/90 SOLENOID-OPERATED VALVE FAILtRE DATA i
DOC PLANT EVENT LER No. OF FAILED SYSTEM MAutffACT MODEL ROOT REP CORRECTIVE COMMENTS REFERENCE TP/ FC I
NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DOCUMENTS Olff l
i 277 Peach Bottom 2 10/05/89 89-023 One sinding Main steam Automatic 6910 20 tnadequate No Replaced SOV Reference LERs See
Valve -
manufacturer's and revised 277/86-003, coments stug Coppany instattation instattation 278/85-018, (AVC) instructions and 278/86-016 maintenance procedures 2 78 Peach Bottom 3 09/30/85 85-015-01 One Leaked ADS backtg>
Target Not Not Specified Yes Replaced SOV Previous See No 03 nitrogen Rock Specifi with an simitar
' Conuments ed upgraded one occurrences reported in LERs 277/85-01 and 278/85-05 278 Peach Bottom 3 07/11/84 85-C18 One DC coit Main steam Automatic Not Reason for Yes Task force DC SOV failure None Yes 01 (MSIV) valve Co. specifi coit failure recomended co wled with ed not specified testing of DC monestary toss solenoids more of AC power often and resulted in anatyre cwse MSIV closure of future failures.
278 Peach Bottom 3 07/19/86 86-016 One Coll Main Steam Automatic Mot Reason for Yes The de coit en Simitar reactor See Yes 01 (MSIV) valve Specifi coil failure each MSIV's scrarps in 1985 coments Corp.
ed not specified SOV was and (AVC) reptaced.
1986(defective de coit coupled with ac power interruption):
LERs 278/85-018, 277/86-03 280 Surry 1 03/28/84 84-007 None thspecif f Feedwater Maintenance No. Recomected IA Instrument air No 08 ed (FWRV) had been done lines to lines were without proper SOV comected to approved ports the wrong ports procedures of 5 SOVs at inadequate Surry units 1 post and 2 maintenance testing W
O b
. ~..
y
- ~
Page No.
11 06/07/90 SOLENOID-OPERATED VALVE FAILtJRE DATA DOC PLANT EVENT LER NO. Of FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE COMMENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER F AILtJRES
- PART NO.
CAUSE FL ACTION DOCUIENTS OUT '
280 Surry 1 11/12/87 87-031 One SOY contairment Masoneita 3500 ' Improper No Secured SOV viring to -
No 09 wiring isolation n (SOV series instattation unspecified SOV blocked unspecifi caused isolation ed) mechanical valve binding of operator contairment isolation valve's operator 281 Surry 2 01/27/85 88-001-01 Two SOV Contairwent Target 86v-001 Cause of SOV No Repair or Electricians None No 26 tenkage isolation (pr Rock /ASCO /206-38 teakage not replace SOVs trying to essurizer 0
specified.
Isolate leaking vapor space Cause of wrong SOVs tifted sappling) tend lifting:
wrong leads electrical maintenance "personnet error" 281 Surry 2 02/02/88 88-002-01 Two Seat Reactor Vateor V526-56 Inpurities in Sovs replaced no 12 tenkage coolant 83-19 reactor sanpling coolant system isolation water prevented conptete seat closure 285 Fort Calhoun 05/01/86 86-003-01 Two Failure vaste gas Not Not Personnet Non Return SOVs to Fait closed None No 22 l
positions Specified Specifi error e correct SOWS had been of SOVs ed falture changed to fait reversed positions open, resulting in voltane control tank teskage to munitiary building.
286 Indian Point 3 02/11/87 87-002 One Coit containment ASCO 8308 Not Speci' sed Yes The failed The design of LER Yes 11 teskage solenoid valve no. 34 static 85-001-00 control replaced with inverter was one of a isproved to higher attow isolation tenperature of single' design. 3 branch circuits simitar SUV if a short coils were circuit also replaced. develops.
e a
m
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s n
,+
- si.
Page No.
12
.06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE ComENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DOCUMENTS OUT 293 Pilgrim 07/19/88 88-021 Four incipients Potential Primary ASCO 8320 Design error No Reptace SOVs Falture of None No 13.
for' conteirnent, and with ends pressure exceeding control rm,+
NP8320 rated for regulator would -
MOPD turb btdg higher MOPD result in inoperability timits HVAC/SGTS-of 4 SOVs due to exceeding MOPD Limits 293 Pilgrim 01/27/89 89-004 Containment ASCO NP8320 Repelred leaks Falture of 2 LER 89-002 Yes 21-and replaced 2 A0Vs due to air isolation SOVs system teaks.
2 Sovs were replaced as a precaution agaimt exceeding MOPD timits of the Sovs 293 Pilgrim 05/03/89 89-015 One Colt Main Steam Automatic 6910-02 " Random No Reptaced Sov Yes of (MSIV)
Valve O
failure" assen6ty Corp.
(AVC) 295 Zion 1 08/08/85 85-029 Two
" Stuck" EDG building Not Not Not specified Yes Replaced Sovs 40 such valves LER Wo 05 used in both 304/85-015 pitot ventitation specified specifi valve ed mits.
Common-mode failures found during testing.
Additional OtFs ocurred next day at init 2.
295 Zion 1 01/12/89 89-001 One-Failed to Ventitation ASCO 8320 Ucakened colt Yes Reptoced SOV LER 89-001 No 01 shift (service water building)
L e
Page No.
13 06/07/90 SOLENOID-OPERATED VALVE FAlltRE DATA DOC PLANT EVENT LER NO OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE COMMENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER FAltt!RES PART NO.
CAUSE FL ACTION DOCUMENTS OUT 298 Cooper 08/18/86 86-018 one Not Reactor Not Not Not Specified no not Spectfied None None No 21 Specified Recirculatio Specified Specifi n System ed 302 Crystat River 3 01/05/89 89-001-02 None Multiple ASCO 8320/NP Design Yes Replaced SOVs See section See No 13 systems 8316/83 error-MOPD with others 5.1.3 of this coments 20 having higher reptet for MOPD rating -. additional info.
Reference documents: lek 78-054,83-023, 88-013 302 Crystat River 3 04/07/89 89-012 contaiment ASCO 8320 Design error Replace SOV 8 SOVs were See F7 14 isolation coils with affected.
coments (RX cavity coits having Reference cooling correct documents: LER system) tenperature 78-054,83-023, ratings88-013, 89-001 302 Crystat River 3 04/18/89 89-015 Reactor Inadequate Modified SOV 15 coo 1 ant ptrp seisaie supports seat bleed instattation off 302 Crystat River 3 09/26/89 89-034 Electrica HVAC, Design error Modified power intermireting No ' 09 t power containment stopt ies of 1E and supplies isolation, non-1E power Main steam sources to SOVs (MSIV) 304 Zion 2 07/11/84 84-015 Not Specified Internat Main steam Keane 51-170 ticensee could No-Three SOVs to None.
None No 26 teakage (MSiv) not find cause be replaced of failure with envirorsnenta11 y qualifled SOVs 304 Zion 2 08/09/85 85-015 Two
" Stuck"pi EDG building Not Not Not specified Yes The valves Common-mode LER No 05.
tot valve vent specified Specift were replaced. failures foemd 295/85-029 ed during testing.
Aiso occurred on unit 1 the previous day.
40 such vaIwes on units 1 and 2.
f
Page No.
14 06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT
.LER NO. OF FAILED STSTEM MANUFACT MODEL ROOT REP CORRECTIVE CONMENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER. FAILURES
.PART NO.
-CAUSE FL ACTION DOCUMENTS OUT 304 Zion 2 02/03/87 87 001 One 0-Ring Main steam Chicago NSV1-16 Manufacturing No Reptaced SOV Wone None Yes 08:
(MStV)
Fluid
-C-XP defect or Power damage during instattation 305 Kewaunee 07/02/84 84-013 One Colt Auxiliary Johnson V-24 Not Speci'fied Yes The Johnson SOV fattures 82-03,23, No 01-building valves were to resulted in 81-34 special be replaced initiating ventilation with ASCO safegu d NP8320 SOVs as equipment. 59 they faited.
such SOVs remaining would be replaced with ASCOs.ed at next outage 305 Kewaunee 12/16/84 84-020 One Coit Auxiliary Johnson V-24
" Burnt out" Yes The Johnson. Due to LER 84-13 No 01 building coit, root SUV was repetitive special cause not replaced with failures of ventitation specified en ASCO these Johnson NP8320.
SOVs, they were atI_being replaced with ASCO NP8320 SOVs on an as-fait basis 305 Kewaunee 02/11/85 85-005 One Coit Auxiliary Johmon V-24 Colt aburnt Yes Reptated SOV Due to LER No 01 building out," root with an Asco repetetive 84-013,020 special cause not failures of ventilation stated these Johnson SOVs, they were ett being replaced with ASCO WP8320 SOVs on an as-fait basis.
305 Kewaunee 11/28/87 87-012-01 Two failed plus Failed to Containment ASCO NP8314 Design error. Yes Replace SOVs See Section None No 13 -
58 incipients shift Isolation-Pz Conditions and correct 5.1.3 of this r
exceeded SOVs*
regulator report relief,make-MOPD timits settings so up,RCDT that MOPD discharge retings wilt not be exceeded 6
m 9
4
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Page ro.
15 06/07/90
~
SOLEN 0!D-OPERATED VALVE FAILtRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MA8PJFACT MODEL ROOT REP CORRECTIVE Co mENTS REFERENCE TP/ FC
. NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE ft ACTION DOCUMENTS OlfT 305 Kewatsiee 05/28/88 88-007-01 Three plus 7 Failed to contalryment ASCO NP8314 Manufacturing No cleaned and Initiated an LER No 05 incipients
' shift Isotation error refurbished extensive root 87-012 (pzr retief, (tswiuthorized the affected cause analysis, makeup use of SOVs See Section isolation) incorrect 5.2.4.1 of this Ithricant) report.
309 Maine Yankee 08/10/86 86-005-01 One Ground Cardox Fire Chemetron 5-020-0 hot Specified No Replaced Sov Sov failure No 21 fault Protection 074-8 tripped Cardox system system power supply breaker, thereby dirabling the Cardon system.
309 Maine Yankee 05/23/88 88-005-02 Four incipients Not NPSI/chargin R.G.
620WA24 Design error No Modified Sovs in high Mone No 16 Specified g ptmp Lauree ce DCSW system rad. fields not
. suction vent environ. quet.
Failure could cause uncontrolled release of radioactivity to non met.
systems.
311 Salem 2 05/22/89 89-011-01 None Main steam Inadequste No Modified Testing Yes 14 (isotation surveittance testing deficiencies valve) testing circuitry would prevent detection of SOW failure Deficiency existed at unit 2 also 313 ANO 1 05/06/85 88-001 Two Lifting Post Target 80E-001 Design error No SOVs were Incorrectly LER No 08 i
of accident Rock
/81P-00 reoriented oriented SOVs 368/88-001 plunger sanoting Corp.
6N correctly could open upon (spurious smatt increases ectuation in
)
backpressure.
See Section 5.1.4 of this report
Page No.
16 06/07/90 SOLEN 0!D-OPERATED VALVE FAILURE DATA i
~ REP CORRECTIVE CopeqENTS REFERENCE TP/ FC DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT NO.
NAME DAtE NUMBER TAILURES PART NO.
CAUSE TL ACTION 000JMENTS OUT 317 Calvert Cliffs 1 04/01/87 87-007-03 Four incipients Unqualiff Auxiliary Not Not Design error No Deficient Two SOVs on '
~None Yes 28 ed Feedwater Specified Specifi electrical each unit fcLsid electrica ed connections to have t
were upgraded inadequate (EC) connector with Ec electrical I
s qualified ones connections 317 Calvert Cliffs 1 08/22/89 89-015 0
todine Design error Reptace with Sov failure No 15 fitter (o list sels:nicatty could prevent dousing classification qualified SOVs iodine fitters system
)
from performing their function 317 Calvert Cliffs 1 11/13/89 89-020 0
Salt wat(r Design error Replace with 4 SUVs in No 15 ' I cooling (Q tist seismicatty safety system classification qualified SOVs not able to
)
and power withstand sources
' seismic event' power sources for 5 safety-related SOVs not seismicalt) qualified 318 Catvert Cliffs 2 09/05/86 86-006-01 One Seat Main Steers ASCO 8300 Not specified No Sov internals None None No 03 teskage (atmospheric were replaced dtmp) 321 Hatch 1 12/07/85 85-043-01 Nun 6er of failed Seat Containment Not Not Normat Yes Leaking None LER 84-017 No 18 SOVs not spec teakare - isolation specified specifi equipment use valves in 42
-multiple ed or wear penetrations systems repaired,retxti It, or reptoced.
321 Hatch 1 04/15/87 87-004 One incipient Main control Not Not AE design No Redesign main Single SOV None' No 14 room Specified specift deficiency control room failure could environeteta ed environmental compromise.
t controi control system control room hability O
e O
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6 Page Co.
17 06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CURRECTIVE COMMENTS REFERENCE TP/ FC NO.
NAME DATE NLMBER FAILURES PART No.
CAUSE FL ACTION DOCUMENTS OUT 321 Natch 1 03/18/87 87-005 Two
- 1. Missing Containnr;nt ASCO NP8321 Unspecified Yes 1. 7nstatted a 2 desper LER No 00 lock nut ventitat'en missing tock
- situres. (1 85-015-01
'2. Stuck nut./ 2. No caused by plunger corrective missing tock action taken nut on SOV, 1 on stuck SOV caused by stuck because it SOV plunger) tested okay stbsequent to fatture.
322 Shoreham 11/15/39 89-009 0
contaiment ASCO 206-832 Design error, Reorient SOVs consnon-mode No 08 isolation SOVs were to correct fattures having (RX building 206-380 oriented positions potential to standby incorrectly (vertical vs. prevent ventitation) horizontal) fulfittment of safety ftnction 323 Diablo Canyon 2 08/14/85 85-019-01 Three incorrect Main Steam Not None Persomet Yes Replaced SOV Undetected SOV LER 85-014 No 07 wiring to (MSIV)
Specified error (incorrec failure caused SOV t undocunented 5 month loss of wiring change) 1 train of ESFAS actuation of MSIVs 323 Diablo Canyon 2 12/21/85 85-022 One Open Feedwate-Not Not leproper No The wiring SOV is a LER Yes 09 circuit specified Specifi wiring comection was piecepert of 275/85-030 ed instattation property the FWRV and txmped reteriminated junction box other similar 50Vs' terminations were inspected.
324 Brunswick 2 09/27/85 85-008 Three Dise-to-s Main steam ASCO 8323 Nydrocarbon, No Reptaced Sovs Consnon-mode None No 12' eat (MSIV) water and high faltures. See sticking tesperatures Section 5.2.3.1 caused of this report.
degradat on of i
seat material.
Page Eo.
18 06/07/90 SOLENOID-OPERATED VALVE FAILtRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE CopWEENTS REFERENCE TP/ FC WO.
NAME DATE NUMBER FAlltRES PART NO.
CAtJSE FL ACTION DOCUMENTS OUT 324 Brunswick 2 10/15/85 85-011-01 Two DC colt - Main Stews ASCO WP8323 Licensee No Replaced 50Vs. None None Yes 01 (MSIV) suspected Extensive chloride fatture corrosion analysis initiated.
324 Brunswick 2 01/02/88 88-001-05 Four Failed to Containment ASCO Stitt tnder Yes Replace SOVs. Four previous Yes 19 shift isot./drywet investigation.
Performing similar t floor and Fomd debris extensive failures had eqpmt drain and oil film failure been sumps on one SOV.
analysis esperienced Suspect high tenperatures from self heating of energized SOVs 324 Brunswick 2 06/17/89 89-009-01 One Failed to Drywell ASCO Not Suspected that No Replaced SOV Extensive No 12 shift purge ara specifi foreign analysis of vent ed particulates root cause was found in the not totetty SOV had conclusive attacked elastomeric parts of the SOV 325 Brunswick 1 02/28/87 87-005-02 Two Discs contairemt Vatcor V52645-Not specified No Replaced SOVs SOV teskoge None No 03 isolatios 5683-14 found during LLRT 325 erunswick 1 07/01/87 87-019 One Stuck Main Steam Target 1/2-SMS Excess Lectite Yes Refurbished See Section LER No 17 plunger (MSRV)
Rock
-A-01 used by SOV 5.2.2.2 of this 87-020-01 manufacturer's report field rep 325 Brunswick 1 07/03/87 87-020-01 Four Stuck Main steam. Target 1/2-SMS Excess Lectite No Reptaced SOVs See Section LER 87-019 No 17 plunger (MSRV)
Rock
-A-01 used by 5.2.2.2 of this manufacturer's report field rep e
e O
4
s 4'
Page No.
19 06/07/90
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SOLENCID-OPERATED VALVE FAILURE DATA DOC PLANT' EVENT LER No. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE CoppIENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER FAILURES PART No.
CAUSE FL. ACTION DOCUMENTS OUT 327 Sequoyah 1 05/18/84 87-020 Not Specified Not.
Not Not Not Design error No Plant' 1E SOVs were None No 14 -
Spw ified Specific 5 Specified Specifi modifcations not protected ed to protect from water vulnerable 1E spray iAlch equipment -
coutd emanate from pipes-iAlch were..
vulnerable to l
an SSE 328 Sequoyah 2 08/30/84 84-014-02 One Seat Feediater ASCO 8320 Design Error No Replaced SOV An incorrectly None No 13 leakage selected SOY fsited when put in service where its MOPD limits were r
l exceeded 328 Sequoyah 2 06/11/88 88-026-01 Two incorrect Auxiliary not Not
.Inadev; ate Yes Reconnected Incorrect None No 07 external feedwater Specified Specifi maintenance SOVs correctly external wiring wiring tevet ed configuration to 2 SOVs control control 328 Sequoyah 2 06/06/88 88-027-01 Not Auxiliary Not Not Inadequate Yes Replaced None None No 07 l
Spec!fied feedwatee Specified Specifi electrical diodes missing ed maintenance from externet circuitry connecting 2 SOVs 331 Duane Arnold 01/10/84 84-004 Two Blockage StancRyy ASCO 8316 Foreign Air path No 12 of filtration materiet in cleaned internet instrument air t
passagewa l
Y l
331 Duane Arnold 01/28/85 85-002-00 One Diaphragm High Skimer L2DB515 End of No Replaced SOV None None No 17-l pressure Electric 0 tife/ excessive coolant time between injection maintenance l
M Page No.
20 06/07/90 SOLENOID-OPERATED VALVE FAILtRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MAIRNACT MODEL ROOT REP CORRECTIVE CO M NTS REF9ENCE TP/ FC NO.
NAME DATE 9RMBER FAILURES PART NO.
CAUSE FL ACTJON DM1ENTS OUT 331 Duane Arnotd 05/27/88 88-005 One Not Fire Electro-M 2010008 Design error no Replaced SOV Licensee had mone so 14 -
Specified Suppression anuet 3
and inadequate upgraded SOV with an (Chemetro post n Corp.)
saintenance incorrect one.
testing Deficiency was not found during post maintenance testing.
331 Dusne Arnold 03/05/89 89-008 One Colt Main steam ASco NP8323 Moisture No Replaced SOV. 7 other simitar Yes 11 (MSIV) intrusion from Tightened SOVs were steam leak /
enclosure subject to inadequate covers of moisture torqueing of other similar intrusion enetosure SOVs.
failure due to fasteners c-~.. a torqueing deficiency 333 Fitzpatrick 08/20/85 85-022 One Electrica Main steam ASCO Not Maintenance No SO S replaced AC coit had None Yes 09 1 fault (wSIV)
Specifi personnet and rewired been connected ed error in correctly to DC source external and DC coit had wiring been comected to AC source 333 Fitzpatrick 11/22/85 85-027-01 One Sov Main steam ASCO NP8323 Brass stiver No cleaned /refurb MSIV mable to Mone no 12 unable to (MSIV) due to cross ished SOV close threading air check other seat line fitting for similar property problem 333 Fitzptrick 08/03/89 89-013 None Containment Design error correct wiring so 07 error isolation 334 Beaver vattey 1 06/07/88 88-007 One Not Dieset Johnson Not mot specified No Replaced SOV EDG mir start None no 22 SOV faited Specified generator Specifi air start ed 336 Mittstone 2 12/31/86 86-021 Two Broken Reactor Vatcor V526-60 Suspect No Replaced 17-7 Prior to event mone no 03 springs Coolant Head Engg 42-3A hydrogen PN springs of these SOVs had in SOVs Vent Corp.
embrittlement att simitar been teeking Valcor SOVs and had been isolated 4
O 4
r
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n i
s i i s i
=
o Page No.
21 06/07/90 SOLE 40!D-OPERATED VALVE FAftuRE DATA l
DOC Plant EVEur LER WO. (F FAILE9 SYSTEM sameurACT NODEL e0OT
- EP CORWECT!vE COMREttTS WEFF#ENG 17/ FC Doctp4ENTS Stff NO.
NAME DATE uuRBER FAILUeES PART WO.
CAUSE FL ACit0N Tes 82 336 Mitts'ene 2 01/02/87 87-002 the Diaphrsspa mein ASCO 8262 mot specified Yes inspected e d reptoced teskage feeduster 338 morth Arrie 1 02/02/84 84-005 6 failed and 54 Electrica Centairunent veteor vetcor Ins + gaste teptoced 6 StWS feited Of (FWV) incipients 1
isoletion and ASCO 526seri cerdsit f ailed Sovs and 54 Sovs hvisture FW. s es seeling and seated att were instattad smethods did deficient incorre-tty in intrusion controt/ pest not meet erfrs condtsit seats both tetts
)
)
l spacs to meat IEEE-324 q.seti ficatiens 336 worth Anna t 11/23/87 87-020 Two no Main steam Copes-vut set
- et Specified No IMer To peevent mene me C2 Spr
' fed (Atmos #ic can Speciff induction recurrence of Dtsap vatves) ed circuits were this type de-energired event, an in order to evetustien to start the instatt condensete
- fit ienet ptsps and tewet tultches begin will be secondery parforwed.
systee recewery actiens.
338 North Anno 1 01/06/88 88-002 One Wet condenser mot mot mot Specified Yes septoced Sov mene sone Yes 21 Specified watertem Specified Spaciti ed 338 worth Anno 1 03/11/88 88-011 Nine
%ish Contairvett ASC) eP-1 Design error Yes Reverted S0Ws Failure to LER Wo 14 vacutse w ation isotation series to sieet fetlow 337/87 annufacturer's seresfacturer's 01 instructions instetIatien instruetlens modified the SCWs' s?rfervience eruf gsstification.
I t
u
a e
Page No.
22 06/07/90 SOLEm0!D-OPERATED VALVE FAILLME DATA DOC PLANT EVENT LER
- 0. OF FAILED SYSTEM MANUFACT NOBEL ROOT WEP CON #ECTIVE CtpMEWTS REFEeEuCE TP/ FC
- 0.
- AME DATE nupSER f MILtRES PART WO.
CauSE FL ACTION DOCIMEWYS tR7T 338 wxth Arne 1 03/15/88 88-012 One mot Compenant ASCO mot met Specified Yes SOE frem
- ene LER 88-011 to 02 Spacifled Cooting Sem ifi 1-CC-TV-t m Water ed was instett M on 1-CC-TV-1038, and the SOY frem 1-CC-TV-1038 was refurbishad and instetted on 1-CC-TV-103A 338 worth Anno 1 07/19/89 89-014 1
0-ring Turbogmeret Parker-us MRFu16M O-ring pinched so Reptsee 0-ring Segetemmtet LER 88-013 Yes 03 or (ERC) nnefin N0834 dsring Sov info ebtaimd refurbishamt frem ticensee by turbina 5/16/90, p.t.
manufacturer's OrmteirV asintenance C.W. Atten tes=
344 Trojan 04/16/87 87-009 set Reetter mot met Desig vinstatt no septoced mene mene no 28 Spacified coolaret Specified SpecifI etien error sptices which (PORV) ed did ret meet EO instettetion ressirements 346 Davis-Besse 09/1;/84 84-013-01 One not main steam Centrot mot mot Spacified Yes septoce or sot is a mene no 21 Specified (Atmospheric Ccapnne*tt Specifi refurbish S0W piece-port of Vent)
Internati ed the etmospheric onat vent vetve's eir-eperated centretier 346 Davis-Besse 01/03/86 86-006-01 Thirty two Coit mot ASCO met Feiture to Reptoced $0V Colts en En gene me 17 incipients specified spacifI perform coits Sovs had baan ed preventive in service unintenance bayantf their i
when regsired quotified lifetime e
l
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O Page No.
23 06/07/90 SOLENOID-0BTRATED VALVE FAtttJRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM Maut >ACT PODEL ROOT WEP CoR#ECTIVE CopeIEuTS WEFEREeCE TP/ FC NO.
NAME DATE NUMBER TAILURES PART NO.
CAUSE FL ACTION DOCUMEeTS titif 346 Davis-sesse 12/07/87 87-015 One Sov Instrssamt ASCO 1179237 mot Spacified no neplaced Sov, Feiture of Sov sone Yes 21 vented air dryer instrisent air caused toss of air dryers instrtsernt reptoced with air / reactor tggradad ones trio. O-rings on several SOVs in turbine hyposs systee
'so found
<>9radad 348 Farley 1 01/18/87 87-005 Two not Cmteiruimt ASCO 8316 Ur*newn me 1 50V closed Rededst Sovs mene no 20 Specified isolation en additienet in one (conteirrent etteapts.
pe=*tration treoord S0W to failed to close surp discharge) be inspacted subsequant to shutdowi.
348 Farley 1 07/21/87 87-012 84 incipients et inadagast mot mot wot soot cause of No Att accessible 84 SOVs et each mone no 28 trech unit e
Specified Spacified Spactfi inedequate SOVs'instettet tsilt were found electrice ed sptices and ions modified not to be i
terwinetions to en o m roved instetted in instatt.
not stated E0 splice end eccordance with (splices /
termination EO requires terminets configuration (splices and
)
on a priority jtmetion box basis.
comections) 352 timerick 1 05/09/88 88-017 one teskoge peector stdg ASco 8316 mot Spacified no neptoced Sov Licensee could mene no 20
-stug Ventitetion not determine stuck in cause of SOV arid-posit feiture.
ion Cetted e
" component failure of toeneun causea 352 Limerick 1 03/14/89 89-019 0
Electrice RK building Design errer Seeted Peter.tiet for no 07 L
ventitetion (EC).
electricot 4
s, failure /m InsdegJete conduits feltures oisture ceneksit intrusion seati9g for potentlet HEL8 emircrument
Page No.
24 06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM Mm4UFACT MWEL ROOT REP CORWECTIVE COpuuENTS REFEREuCE TP/ FC NO.
NAME DATE.
WUMBER FAILURES PART NO.
CAUSE FL ACTION 000mEsts GUT 354 Nope Creek 08/28/86 86-063 12 incips ets
- ot conteirveent ASCO NPS316 Deste error so Reptoced ett Felture of mene me 13 Specified AtmosgAere twelve Sovs non-0 Controt with ones reguteters heving e could have higher MOPD caused feiiures rating.
of the SOVs.
354 Nope Creek 02/24/87 87-018-01 One Failed to Main Steam Autometic Mot Foreign No Reptaced Foreign LER
- o 03 shift (MSIV)
Valve Specift meterial feited Sov and meteriet in 87-037,038 Corp.
ed inside SOY its manifold Sov,Pttoger in (AVC)
- body, essembly.
SOV not per manufacturing Reptoced 7 deste defect, and SOVs for other (incorrect irndeqJate MSIVs. Sent length),
instatIation falted S0v to mainting screws steptier (GE) on junction box for anstysis were loose.
354 Pope Creek 10/10/87 87-047 One Failed to Mein Steam Target Not Inadaquete No The Feiture caused wone me 12 shift (wSRV)
Rock Specifi protection of motfunctioning by intrusion of ed MStVs <ksring SRV and its sen & testing plant SOY piece-part grit iAicit was construction were replaced used dJring in kind.
plant construction 361 San onofre 2 01/09/86 86-004 Two Coit Feedwater Not mot poisture No The velves mone Pena Yes 11 spacified Specifi intrusion -
were reptoced ed fautty conduit and visust comection inspectiens suede of the conduit connections of sioiter Sovs 361 San onofre 2 12/17/87 87-031-01 One Corrosion Main Marotte Mv233C Inadequete Yes Reptoced Sov, veter and ttR Yes 12 of power Feedwater Scientifi /
maintence te-pinst foreign 206/86-004 teads and MFiv) e Pv238C istructions block,and meteriet teminst Controls power teeds.
intrusion block Inc.
Seeted conduit (inodequetely connections seated con & sit preperty.
comactlon) e e
4
6-Page No.
25 06/07/90
$0LE40!D-OPERATED VALVE FAILtJRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MA40 FACT MtBEL N00T REP CDRRECTIVE CtpsEgTS REFEaENCE TP/ FC No. #AME OpTE NUMBER TAlttJRES PART No.
CAUSE FL ACTIOI 0001pIENTS OUT 366 statch 2 09/21/84 84-021 One Gasket Mein Steent ASCO mot not Specified so replaced afone 18ene Yes 03 (MSIV)
Specifi gesket ed 366 Match 2 01/20/88 88-004 utsuercus Leakage Containment Target 75F-009 ins +g.sete No Reverse See Section LER mo 08 isolatim Rock
/7567F instructions /
orientation of 5.1.4 of this 366/86-020 forvel use and eeny SOVs/
report (aany reptace falied wear systens) e-rings 366 Hatch 2 02/12/88 88-007 Twetve Not Contairwomt Target 73C-001 Ine+ gjete no Reversed See Section mone so 06 Specified Isolation - Rock
/75F-00 instructions /
orientation /fo 5.1.4 of this Torus 9
design r tmlt one report Drywell deficiency instatted strerigar Vactase springs Breaker 368 A40 2 04/24/87 87-003 Two Seat Reactor mot set Seat testage no Reptsced 50V Centern for mone so 03 teskege Coolant specified Specifi arti installed teek causing (pressurizer ed a colIecto-corrosien for any future demoge to other high point teskage components vent) 368 Amo 2 04/29/85 88-001 2
Leakage Contairment Target 80E-001 esckwerds Reinstetted See section me 08 isolation Rock instattetion SOVs in 5.1.4 of this due to reversed report for (pess) ine & quete orientation additionet info installation instructions Refur'ished Vatve had to 14 368 ANO 2 02/16/89 89-003 0
Containment Target 74F Design error-o isotation Rock incorrect 50V. Checked exceeded EC assessaient of others for t*fe 6 years (hydrogan ano(yrer 50V sinriter dasign prfor to seipting) tife-fsiture error discovery of to eccount problege for bestic dJe to energitation 369 McGuire 1 07/23/84 84-023 One Seat pain Borg mot wydraulic so Adjusted 50V sone mone ves 03 defonasti Feedwater Warner Spaciff fluid was and sedified ed tesking system en k
Paga No.
26 06/07/90 SOLEM01D-OPERATED WALVE FAILtJRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM futaVFACT MODEL ROOT DEP CORRECT!wE COMM4TS WETEWEmCE 1P/ FC
- 0.
NAME DATE NUM8ER FAILtJRES PART NO.
CAUSE FL ACTION 000mE#TS OUT 369 McGuire 1 09/19/85 85-028 one plus three Cable Post Yetcor 526-529 Personnet so Att four Simriter velves mene so 11 incipients terwineti occident 5-45 error vetves were checked et tJnit on sanpting (instattation
- repeired, 2, and found to seating not perfonned resented.
be okay per Wiring on ett instattation other valcor specification) 526 series SOVs et station to te tJpgraded and seats reptoced 369 McGuire 1 04/15/87 87-009 One System Main turbine mot Not modification wo Change system mene Yes 00 perturbet Specified Spe iff of design and meintenance
<peration logic ion ed maintenance schedule to and time of evoid testing preventive while at meintenance had power.
L,3,
,.-J.
Both factors contributed to a reector trip.
370 McGuire 2 06/24/85 85-018-01 Two (of the same Coit ami main sorg-warn mot 1-coit wo 1-repf oced Second feiture mone Yes 01 SOV) short feedwater er specifi failure - not SOV.
2-dried occurred prior circuit ed specified.
2-water front to complete short circuit
- SOV, instattotion of
- water sgrey electricet box replacemmt 50V onto open electricot box 370 McGuire 2 08/27/86 86-017 One toit Main Borg mot Not Specified Yes SOV colt men None LER Yes 01 Feedwater Werner specifi reptoced end 85-018-01 ed originot coil was sent to the manufacturer for anetysis.
373 LaSatte 1 08/29/84 14-051 One SOV (3 Electrice Mein steam Crosby Imr-2 Cause of short no Reptoced SOV Caused SRV to wene so 11 metfunctions) t ground (MSRV)
Vetve to groumf not lift three specified times S
e O
4
Page No.
27 06/07/90 SOLEWOID-OPERATED WALVE FAILURE DATA DOC PLANT EVENT LER N0. OF FAILED SYSTER MANUFACT MODEL WOOT REP CORWECTtW COMMEWTS
- EFE8EacE TP/ FC 00CJRENTS Stf7 NO.
CAUSE FL ACTION NO.
NAME DATE uuR8EW FAttt. IRES PART 373 LaSatte 1 02/02/85 85-006 Four Diag
- cage meector ASCD 8316 Diaphrayas Tes Rebtritt sovs, Will change no 03 s
building lost their cycling 50Vs to fu.scleer ventitation resitience frerpsancy to <psetiffed be increesed uP8316 model 3 73 LaSatte 1 03/12/87 87-013 Sin incipients mot Main Steam not mot migh drywatt no Anotyre Three SOVs mone me to effects of dectered specified IMSRV)
Specified speciff tem erature high drywett inoparable.
ed temerature Three 50Vs suspect due to high local temperatures 374 LaSatte 2 06/08/84 84-033 One plus eeny Passagews Contairvient ASCO 206-832 SOV was aepositiomd Other simitarly no 08 ivprocertv
$0V of fected SOVs incipients y blocked isolation ware positioned repositioned or reptseed 3 74 LaSatte 2 11/20/84 84-076 One Coit Turbine not set Junction bon no Reptaced Sov wone mene no TT Steam Bypass Spacified Spaciff was futt of ed water of t.rdnown origin 3 74 LaSatte 2 07/31/86 86-013 mone - Many Electrica CRD, RCS ASCD See Desipi error Yes Repeired ett TE equipment LER 86-012 me 28 effected used incipients t
- recire, cerw=mt electrical t.mquotified connectio RCIC, s
terminations electrical ns service to meet connectleas.
water, ftoor
<pset ification SOV e t nos.
drain, air regtsirements WWA-206, NP206, NP-8320, uP-8323 374 LaSatte 2 01/17/87 87-002 One lenkege Feedwater Vateor v52660- Woot cause of ves Refurbished SOY body and
- ene No 12 5292-16 corrosion, Sov stem correded, SOY fitted with dirt and dirt, and e-ring deformation e-ring wes deformad not stated I;
I M
Page No.
28 06/07/90 SOLENCID-OPERATED VALVE FAILURE DATA DOC PLANT EENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE ComEw?S REFE8EeCE TP/ FC NO.
NAME DA"E erJNBER FAlltNtEs PART 90.
CAUSE FL ACTION 00GMEWT5 TRIT 382 Waterford 11/11/87 87-028
.One sov Mein steen Fluid 7WMP477 Not specified No Repisced 50v S09 feited None Yes 05
" stuck (Msiv)
Contret 4-600K8 daring testing.
open" Inc.
65 LER reted previous l
snrelated SOW failure due to opm coit.
387 Susq;ehanne 1 02/25/84 84-010 One sov Main steam not mot not spacified so Reptoced sov sov stuck op m mone Yes 05
- stuck (Msev) specified specifi causing 3RV to open" ed remain open 387 susquehanne 1 06/13/84 84-044 Several
- Discs, Contret Red AsCD WW-176-Contamination Yes Refurbishad see section mone so 12 repetetive seats Drive 816 of the air sovs,tegredad 5.2.3.3 of this failures system and disc wateriet report elevated from tenperatures polyurethene to viten 38/ susquehanno 1 07/06/M 87-023 One Coit Contairvamt Cirete mot
- Surned open* Yes Reptoced coit Open cost foted mone no 01 Vacutse seet spacifI colt on same vacutzt Retief Controts ed breaker in 10/82. A init 2 vacutsa breeter else had a simiter Circle seei sov coit failure in 4/87 387 susquehame 1 02/04/89 87-006 Three m echanic s>4pression Cirete Root cause Yes Reptoced One 50v failed, LER 87-023 Yes 19 otty chenber seat onetysis feited sov and houaver two bound" drywett planned but eight simiter simiter sovs vacutse not complete ones had
- problems" breaker yet
(= problems" not
- spacifled) 388 susquahanne 2 01/10/87 87-001 Two Not Reactor AsCD not mot specified wo Reptoced SOY mene none Yes 02 specified Building specifi Chitled ed Water G
O 9
w_,
_m-,_
.m_-__
.w
Page No.
29
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06/07/90 SOLEWOID-OPERATED VALVE FAf ttJRE DATA DOC PLAwT EVENT LER NO. OF FAILED SYSTEM MA40 FACT MODEL ROOT WEP CORRECTIVE CDGEENTS WEFERE4G TP/ FC D00mENTS S 117 NO.
CAUSE FL ACTION NO.
NAME DATE muMBER FAILURES PART Yes Reptoced 50V ticensee shst LER 86-036 so 21 conteirusent ASCO down plant 388 Susquehems 2 02/27/89 89-003 One isolation irsteed of (recircutsti continuing on pump eperation et chitled reduced power water per tech specs so 21 389 St. Lucie 2 08/16/89 89-006 One Not Hydrogan VetCor
$2600-5 Not specified no Septoced SOV specifled soneting 15 395 Sumer 06/29/86 86-011 One Electric Feedwater Not Not Ouidation of No Electricet mone mene Yes 07 comector (FW1V) specified specifi cemector pins connector and ed 50V were rept oced.
395 ser 12/02/88 88-012-01 mone many Ground Mein Steso ASCO wot Design no isolated 50V Fim.ed that mene no 14 incipients faults and Specifi deficiency contacts to ground f eutts Feeduster erf prevent could cause spurious spurious Sov octuations actuations Incorrectly no Modified Cceanon M LER 88-012 no 07 02/17/89 89-003-01 None, 3 Electrice Mein stese incipients 1
(MSIV) designed wiring felture 395 Sumer iso!stier, potentist for grounding att 3 MSIVs retey 397 WMP 2 03/22/84 84-027-02 Fifteen Ground Mein steene mot mot 50V Yes Reptoced Events et WNP LER me 14 faults (MSRV) spacified 3peciff susceptibility defective occurred during 84-027-01 ed to spurious Sovs. Tested startup actuation due potentielty testing.
to ground ef fected 50Ws. Ceaumon-mode feutts Voltage spike feiture stypression potentist.
diodes were Previous festatted en sletter events ett MSRV+ ADS et to Sette +
SUVs Su W anne 397 WMP 2 07/23/85 85-050 Two feitures (1 Diephrege Fire Wot mot Root cause of so 1-Reptoced mone mene no 08 SOV)
/seet protection Specified Specifi diophreye diaphregsvestv ed leakege not e seet.
2-leakege specifled, backwords Bachwerds bonnet bomet due to
- repeired" insdew ete maintenence
Page No.
30 06/07/90 SOLENOID-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CDRWECTIVE C3 WENTS REFERENCE TP/ FC NO.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DOCUMENTS Otif 400 Shearon Harris 1 d2/08/85 88-006 Two Failed to Energmey Target 790-024 source of Yes Tha failed Common-mode mene me 12 close service Rock debris SUVs were failure water p g accumulation repaired. No effecting both seat water not specified Statement sede trains of supply about actions Emergmcy takm for Service Water rewevet of debris or prevention of adtfitional debris 400 Shearon narris 1 05/13/88 88-012 Two Failed to Emergency Target 790-024 Debris in Yes Repaired SOVs 14 shift service Rock water and blocked water seat off source of water sagply debris 400 Shearon parris 1 09/09/88 88-026 Eleven or more Internet Contain e t Target Eleven Manufacturing no tJnqualified Ca pone no 06
/ read isolation Rock models &ficie m parts of 1E failure switch (meny harsh env.
potential for wiring systems)
SOVs replaced 1E Sovs for with gaatified harsh ones.
environments.
Corrective Sovs for action for ex-centainment non-hersh env. also deficient.
Sovs not specified.
409 ta Crosse 12/03/84 84-022 One seat isolation ASCO 8210 mot Specified Yes Reptsced S0t mene mona No 03 teskage Condenser 409 La Crosse 04/20;$5 85-008 one Colt control Rod Royet mot set Specified Yes Replaced S0W None LER 81-13 YES 01 Drive indastrie Specifi s
ed 409 La Crosse 05/17/85 85-012 One Seat control and Royat not Root cause of Yes Reptaced S0w mone wone Yes 12 Drive Industrie Specifi metet chip in s
ed S0W seat not specified e
S S
_,.a.
.n.
e e
Page No.
31 06/07/90 SOLENOID-OPERATED VALVE FAtttlRE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MBE;.
ROOT REP CORRECTIVE COINEENTS REFERENCE TP/ FC WO.
NAME DATE NU4RER FAILtJRES PART NO.
CAUSE Ft. ACTION DOCIMENTS IRif 409 La Crosse 07/08/86 86-020 One Colt contret mod Royet Not thcertain, Yes Reptaced Soy There have been LER 85-08 Yes et Drive Industrie Specifi water T previous s
ed intrusion or scrans due to rondom colt the scram failure solenoid suspected shorting out.
409 La Crosse 07/19/86 86-024 One Electrice Reactor ASCO 8300 Persemet No Replacel 50v ESTAS None No 11 t short cavity error-actuation, ventitation spisshed water cascading event on SOV 409 La Crosse 12/09/86 86-036-01 One Coit control Rod Reyst Not Uncertain, Yes Reptoced There have been LER Yes 18 Drive Industrie Specifi ageing or several SOVs. 8 previous 85-06,86-0 s
ed moisture Retacemmt of scrams due to 20 intruslen Sovs will be these 50V suspected incitrJed in failures. Sov CROM thet failed was preventive about 20 years unintenance old.
program 410 Nine Mite Pt 2 06/22/88 88-025 Numerous hydraulic Feedwater Keane 33896 Foreign object No Reptoced Sov, Sov is None Yes 03 internal psrts Control in Sov, due to etso reptoced piece-port of Unit manufseturing simiter S0vs tevet centrol deficiency or in other valve failure to trains because instatt filter of serious screen degeadetion of their internets 414 Catawbe 2 10/11/86 86-045 One Failed to AFW (steam SOV Rectvmected Soy feiture NO 08 shift admission to incorrectty 50v property defeated manuet turbine) installed per start an incorrect capssitity of design drawing AFU turbine 416 Grand Gulf 1 02/10/85 85-007-02 Three Core-ptog Main Steam ASCO 8323 FtsSS No Reptoced ett 8 See sectier, None Yes 05 nut (MSIV)
Msty Sovs 5.2.4.4 sticking s
a Page No.
32 06/07/?O SOLEN 010-OPERATED VALVE TAILtJRE DAYA DOC PLANT EVENT LER No. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE ComENTS PEFERENCE TP/ FC
- 0.
NAME DATE NUMBER FAILURES PART NO.
CAUSE FL ACTION DOCUMENTS OUT 416 Grand Gutf 1 09/25/85 85-038-01 One Colt crywett ASCO 8320 Excessive no Falted SOV Licensee stated mone so 11 equipment corrosion replaced with at the 50V drain within the a d aticate did not need to coit housing be believed to be envircrvuentat ty caused by seated water which entered during ptant construction 416 Crrnd Gulf 1 07/30/86 86-026-01 One Colt Control pod ASCO 1050602 Particulate so s'eptaced SOV, Particutste mene no 12 Drive SP1 ocetsuutation system filters accumulation on the valve to be checked resulted in an seating and sagted inevertent surface for control rod particulates withdrauet 416 Grand Gulf 1 01/08/87 87-001 One SOV Offgas ASCO 8320 mot specified so Not specified Modified system wone no 00 failed in sa mling
- specific mid-posit actions taken ion regarding SOV not stated 416 Grand Gulf 1 03/15/88 88-010 Orw!
Loose control Rod ASCO Not cause of loose no The tonse Licensee to wone Yes 07 terminst Specifi connection not terminet evaluate design box ed found cormection was change to connectio eteened &
igrove n to SUVs tightened.
rettability of Other SOV power teeds terminst connectians checked, ett were okay 423 mit(stone 3 09/06/86 86-051 Not Specified
" Failed Feeduster Not Not Intermittent No Att local mone None Yes 01 electrica Specified Specifi open circuit, terminations tty" ed root cause on the SUV
- istnewn, wiring to be suspect checked for vibration and tightness steam dJring the I@ingeomt next shutdown.
from a pecking iesk e
O e
e e
\\
e e
Page No.
33 06/07/90
~
SOLEWOID-OPERATED VALVE FAlttJmE DATA DOC PLANT EVENT LER N0. OF FAILED SYSTEM MANUFACT MODEL ROOT REP CORRECTIVE COMENTS WEFEREWCE TP/ FC NO.
NAME DATE mum 8ER FAILUaES PART WO.
CAUSE FL ACTION E M NTS tRFT 423 Mittstone 3 03/07/87 87-006 One Colt Feedwater skimer V546620 Cause for open Yes septoced S0W S0W was LER 86-051 Yes 90 (open 0
circuit not operating circuit) specified within its
" design life" 423 Mittstone 3 05/06/87 87-024 One Sov immtd Emergency Circle N2990-9 mot specified no Failed air Failed Soy mone so 20 not shift dieset seat 617 start SOW and resulted i'.s within generator the dieset's slow (out of spec air start rededant 50V spac) EDC were replaced starting time with new ones 423 Mittstone 3 09/23/87 87-034 One Colt Feedwater skinner V5m6620 soot cause of Yes Reptoced sov S0W controts LER Yes 01 Electric 0 colt failure hydroutic cit 87-08/86-0 (open circuit) flow to FW1V 51 not determined.
Colt was within its "qJetified life" 424 Vogtte 1 01/22/87 87-002 Eight incipients Potentist Main steam Lesne not Design error no Instatted a Potential for mone no 13 for MOPD specifi relief valve c-A ed on each MOP 0 failures hy& eutic dJe to bestup e, stem to of hydraulic timit pres Asre fluid. See to betes MOP 0 section 5.1.3 timits of this report.
424 Vogtte 1 04/24/88 88-013 One Coll Feedwater Skinner V5M6559 Colt burnor.
No peptu.ed Sov Sov is a Pone no Of Electric 0 and simiter piece-part of SOV on other A0W contretIleg train of FW1V FWiv control system 440 Perry 06/30/86 86-030 One seat Contairunent ASCO 8320 Oust from no Replaced soy mene mone no 12 teskage Wesset and instrument air Drywell prevented Furge proper valve seating
.r aw,.
-e
a Page No.
34 06/07/90 SOLEmotD-OPERATED VALVE FAILURE DATA DOC PLANT EVENT LER NO. OF FAILED SYSTEM MANUFACT MSEL ROOT REP CORRECTIVE C0pWEENTS REFERENCE J/ FC NO.
NAME DATE NUMBER FAILURES PART so.
C#JSE FL ACTION 000 MENTS OUT 440 Perry 02/27/87 87-009 Two Air Enumency Mumphrey TOG 2El-Falture dse to Yes Replaced Seth Slauttaneous mone me 17 leakage Dieset ProdJets 3-10-35 entended S0Ws.
s J.-
(through Generator service with Returned failure of both etestomer Control Air high local feited SOVs to diesets. Detey ic parts) tempn etures EDG in repelring and continuous manufacturer teeking SOWS energitation.
for anetysis. contributed.
SOVs in svc 10 Witt tygrede See Section years and preventive this report never had m maintenance and etesteners 440 Perry 10/29/87 87-073-01 Five Sovs <n two Etestener Main steam ASCO NP8323 Weet and Yes Rwleted or C.d insp #pt Yes 10 occasions ic seats, (stSIV) soisture from refurbished feitures. See 87-024
- dises, steem teoks SCVs Section 5.1.1.1 etc of this report for additional informetion 440 Perry 03/10/88 88-010 One core Auxitiery ASCO 8320 IWte no Reptoced SOV. Failure of SOV mene so 17' shaft Building (no) instituted a results in toss weer VentiIetion preventive preventive of WWCU room meintenance meintenance cooling for this SOY program (reptoce eAen tygrede to fait). Vetve reptoce those had been in SOVs every 2 service for years over 5 years 440 Perry 02/03/89 89-004 One Aunitiary ASCO 8320 Yes Reptoced SOY titensee LER 88-010 no 19 building investigating ventitetion rCot cause 456 Braidwood 1 09/15/89 89-010 One Colt Containment Veteor V526-53 Coit leads no Reptoced with Also reptoced 5 wo 09 Isolation 95-1 tabeled different other simiter (hydrogen beckwards sedet SOV Sovt. Licensee enetyrer) investigating source of aristabeting (merwfecturer vs. plent)
O e
O 4
-o
Page No.
35 06/07/90 SOLEwotD-OPERATED VALVE FAILtJRE DATA DOC PUHet EVENT LER NO. OF FAILED SYSTEM MmeUFACT MODEL ROOT REP CORRECTIVE CO MEufs REFEREWCE TP/ FC WO.
MAME DATE NUMBER FAILtJRES PART
- 0.
CAUSE FL ACTION DOCUMEWTS OUT 458 River Bernd 05/02/89 89-022 Affected Target 77kk-01 E M uerds Yes SOVs See section LER 89-024 to 14 many Rock 3
instettetion reinstetted in 5.1.4.1 for systems.
due to reveese additionet See ctresent inadagsste orientation details instattation instructions 458 River send 04/06/89 89-C24 0
Affected Targat 77EE-01 Backwerds Yes Reversed Potentist LER 89-022 me 08 many Rock 3
in=tettation -
orientation of 4 -. 4 systems.
design error.
SOVs failures. 6 See consnent Inadequate 50Vs had the instattation same instructions.
Instettetten deficiency.
See section 3.1.4.1 of this report for info 461 Ctinton 03/06/87 87-009 One Sov FueI wot mot mot Specified No Reptaced SOY mene mene so 03 failed in Building Specified Speciif mid Ventitatien ed position 461 Clinton 04/14/89 89-019 Electrica Main stese Seitz Design error Instatt heat Failed to maet no 08 L
(WSIV)
(EO).
shrink tubing EC instattetten comactio Inadegsete per EQ requirements ns electrical requirews comector seeting 461 Clinton 11/29/89 89-037 One 0-rings Vacut.se GPE LD240-4 InodagJete No Refurbished no scheduled No 03 relief Controts 20 preventive Sov, reptoced preventive (Sov (GPE) meintenance 0-rings meintenance anspecifi program.
ed)
Foiture discovered during streke testing 483 Catteusy 01/02/85 85-001 One mot feedwater not rot Licensee Yes Replaced SOV Sov is e mene Yes 00 Specified specified SpecifI censidered piece-port of ed this to be a FWiv hydraulic ran&se failure operator h
.2
a Page sto.
36 06/37/90 SOLEeIO!D-OPERATED VALVE FAILURE DATA 00C PLAIIT EVENT LER No. OF FAILED SYSTEtt MAIUFACT SEODEL ROOT WEP CDR#ECTIVE CeuuEENTS REFEWEWCE TP/ FC 11 0. NAME DATE 81UIWER FAILtRES PART a0.
CAUSE-FL ACTION 90CUIEEWT3 tRff 483 Cattowey 02/20/86 86-002-01 none Electrice Reactor heed not het Construction Yes not Specified On 2 occasions Ihree no 28 t
vent entf Specified Specif f and startup ticensee fowd connector cbearicot ed proges=
it had not s
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APPENDIX B DISPOSITION OF ASCO DUAL-COIL 8323 SOVs USED FOR MSIV CONTROL
APPENDIk 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 SOVs 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 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 the NP8323 SOVs under adverse service conditions.
In anti::ipation 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 air packs for baseline testing.
The SOVs to be tested in the MSIV air packs are:
ASCO:
NP8320 V (2 valves configured as recommended by ASCO in Refs.
102,103).
AVC:C4964 Tar 0et Rock: fSMS-S02(modified)
Valcor:
V70900-87V Zeiss: 629-60007 (assembly)
GE and Hiller Company have noted that all of the American SOVs are IE qualified; and that although the Zeiss assembly is not IE qualified, it has been used successfully in Europe.
It should be noted that the choice of a replacement for the NP8323 SOVs can affect the qualification of the overall MSIV air packs (e.g. seismic / dynamic loading).
Final selection of replacements for the NP8323 SOV 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 SOVs 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.**
- 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 1589.
PRELIMINARY CASE STUDY B-1 W
l APPENDIX C GENERIC C0mVNICATIONS ON SOVs l
k
O 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 udlletin 80-17 July 3, 1980 Failure of 76 of 185 Control Rods to Fully Insert During a Scram at a BWR l
Bulletin 80-17 July 18, 1980 Failure of 76 of 185 Control Rods Supplement I 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
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 Information Notice 81-29 September 24, 1981 EquipmentQuantification Testing Experience, Equip-ment Qualification Notice No. 1
-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 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 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
. ~-
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0 Information Notice Number Date Tjtle Information Notice 85-08 January 30, 1985 Industry Experience on Certain Materials Used in Safety-Relatedlquipment Information Notice 85-17 March 1, 1985 Possible Sticking of ASCO Solenoid Valves i
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 Target 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-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 Information Notice 87-48 October 9, 1987 Information Concerning the Use of Anaerobic Adhesive /
Sealants Information Notice 88-24 May 13, 1988 Failures of Air-0perated Valves Affecting Safety-Related Systems Information Notice 88-43 June 23, 1988 Solenoid Valve Problems Information Notice 88-51 July 21, 1988 Failure of Main Steam Isolation Valves Information Notice 88-86 March 31, 1989 Operating with Multiple Supplement 1 Grounds in Direct Current Distribution Systems PRELIMINARY CASE STUDY C-3
o' e
Information Notice Number Date Title Information Notice 89-30 March 15, 1989 High Temperature Environ-ments at Nuclear Power Plants Information Notico 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 Circular 81-14 November 5, 1981 Main Steam Isolation Valve Failures to Close i
PRELIMINARY CASE STUDY C-4
.