ML19350D202
| ML19350D202 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 03/27/1981 |
| From: | Varga S Office of Nuclear Reactor Regulation |
| To: | Abel J COMMONWEALTH EDISON CO. |
| References | |
| RTR-NUREG-CR-0660, RTR-NUREG-CR-660 NUDOCS 8104130782 | |
| Download: ML19350D202 (9) | |
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i NUCLEAR REGULATORY COMMISSION
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March 27,1981
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Docket Nos. 50-295 4
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Mr. J. S. Abel g,/,
Director of Nuclear Licensing
, s s'y c-Coninonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Abel:
We have completed our review of the August 29, 1980 Commonwealth Edison Company (Ceco) response to Item F.1 of the February 29,1980 Confirnatory Order. The Ceco response included a report of past Licensee Event Reports (LERs) at the Zion Station Ur.it Nos.1 and 2.
To evaluate this report we reviewed all of the LERs for these two units or the 1974-1980 time period.
In this review we found that the predomin-e ate reported cause (i.e., over 60 percent of the significant LERs) was the failure of components. Some of these failures were highly repetitive; so nose from Unit 1 were categorized into broad generic groups as shown in Table 1.
This categorization of repetitive component failures into broad generic classes resulted in fewer groups than given in Table 2 of Ceco's review. By doing it this way it is seen that the failures in categories 1, 2, 4, 5, and 7 are ones that can occur in more than one safety system at a
- ine. The more repetitive they are the more likely it is that they could result in concurrent failures. This table also points out recurrent problems in specific systems, such as the blowers and pumps in the radiation monitor systems.
Even though these nine categories are diverse, there seems to be an underlying, design inadequacy; i.e., it appears that the components in most of these categories did not initially conform to an adequate set of design specifica-tions. There appear to be more failures than the statistical ones that one would reasonably expect if these components had met all of the requirements of a good set of design specifice,tions such as ones designating:
1.
The range of vibrating frequencies and accelerations of the component when it is operating.
2.
The composition and state of the surrounding environment; e.g.:
a.
Temperature range f
b.
Humidity range f
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l Mr. J. S. Abel -
' c.
Type and concentration of impurities d.
Composition, density, and size of dust particles.
3.
The type and intensity of radiation.
The temperature range is especially important for high humidity applications where the component has to operate at temperatures above and below 32*F.
Examples of LERs which resulted from inadequate design specifications on temperature range are listed in Table 2.
Also, if possible, the lifetime of the safety components should be specified, so these components could be replaced before they fail rather than after. This could have prevented the end-of-component-life LERs.
The systems interactions which we identified from the LERs are listed in Table 3.
The most troublesome one is the water hammer that occurred with safety injection. To prevent this, Ceco installed J-tubes in one of the Zion steam generators prior to June 1978. It is the NRC's unde.rstanding that CECO
.;ill install J-tubes in all of the Zion steam generators as soon as possible.
In its LER review report Ceco states that, beyond those already corrected, no additional design, procedural and training, or man-machine / human factor inadequacies were identified which could lead to significant degradation of unit operating reliability or safety systems capabilities. We, however, did icentify an inadequacy of this naturc This is in the operation of the a
erergency diesel generators. Table 4 lists the LERs which were caused by poor maintenance, faulty repair, or improper operation of these diesel gener-a: ors. This list is self explanatory. These are not all of the failures, only the human factor ones. The four failures diesel generator 18 had in this 3-year time period puts its reliability in the low 30 percentile of operating experience.
In conclusion, these LERs show that there was a basic design specification inadequacy for many of the safety system components. As a result the required design specifications were eventually determined by the LERs. Most of these have now been taken care of, but it appears that there are still a significant nu.Ders of LERs involving setpoint drifts.
CECO should re-examine efforts to ninimize setpoint drifts in equipment important to safety. Also, to the extent cossiole, component lifetimes should be determined so that they can be replaced be# ore they fail. To a large extent, this effort will be addressed in ongoing ac-ivities associated with the en.ironmental qualification of safety related electrical equipment and specifically, the issue on aging.
CE o should take immediate ac. ion to improve the maintenance, quality of re-
- air, and operation of its diesel generators. CECO could begin this process
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- dressing the recommendations in NUREG/CR-0660, "Enh6ncement of the Reli-t a ility of Emergency Diesel Generators." These improvement programs, if not j
already underway at Zion, should include considerations and recommendations l
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M,r. J. S. Abel -
l fmm the manufacturer of your diesel generators and training and procedures to effectively implement the program.
In this regard, CECO is to submit within 60 days a schedule for the improvements program and an assessment of how the program will improve the overall operation of the emergency l
diesel generators.
Sincerely,
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, Steven A. Varga Cirk Operating Reactors B ch #1 Division of Licensing
Enclosures:
Tables 1, 2, 3 and 4 of Zion LERs cc: w/ enclosures See next page
i v.r. J. S. Abel
- cmmenwealth Edison Conpany cc:
Robert J. Vollen, Esquire 109 North Dearborn Street Chicago, Illinois 60602 Dr. Cecil Lue-Hing Director of Research and Development Metropolitan Sanitary District of Greater Chicago 100 East Erie Street Chicago, Illinois 60611 Zion-Benton Public Library District 2600 Emmaus Avenue Zion, Illinois 60099 Mr. Phillip P. Steptoe Isham, Lincoln and Beale Ccunselors at Law One First National Plaza 42nd Floor Onicago, Illinois 60603 Susan N. Sekuler, Esquire Assistant Attorney General Environmental Control Division 158 West Randolph Street, Suite 2315 Onicago, Illinois 60601 U. S. Nuclear Regulatory Commission Resident Inspectors Office 1:5 Shiloh Blvd.
Zion, Illinois 60099 i
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ENCLOSURE
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Table 1.--Component Failures Reported in LERs for Zion 1 in the 1974 - 1980 Time Period Category
- of LERs m.
1.
Va i v e & va l v e opera tor fa il ures...............................
56 2.
Set point drifts..............................................
39 I
I 2.
- a dia tion moni tor blower & pump fa ilures......................
15 2
- ns trument tra nsmi tter fa ilures...............................
14 i.
F.e'.ay,_ circuit breaker...& swi.tch failures.....................
11 i
Fydraulic snubber failures....................................
11 i
C;trational amplifier, lead / lag module, comparator,
& computer failures.........................................
7 i
E l t e,' n f d s e s...................................................
3 E ad icac tive ga s moni tor fa il u res..............................
3 159 N : r, - r e p e t i t i v e................................................
91 T: t il c c p e r.en t fa i l u r es.....................................
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ENCLOSURE
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Table 2.--Events Requiring LERs Caused by Inadequate Specification of Temperature Range Date Event Zion 1 01/08/76 Frozen instrument lines due to very cold weather 04/13/77 Overheated monitor cabinet due to poor ventilation 12/08/77 Butterfly valve seat contracted due to cold weather 12/14/76 Ice on traveling screens l
Zion 2 01/09/78 Butterfly valve seat contracted due. to cold wea ther 12/14/76 Ice on traveling screens
ENCLOSURE Table 3.--LERs Which Indicate 5ystems Interactions
.'- i t Date Event 1
07/16/7b While compensating for a xenon transient, the temperature differential exceeded limit du'e to a feedwater pump trip.
1 08/11/76 During a test an electrical fault tripped.
a circulating water pump. This resulted in the temperature differential exceeding Tech. Spec. limits for 15 minutes.
1 03/02/79 Water hammer during safety injection.
1 03/16/79 Water hammer during safety injection.
1 06/08/79 Water hammer during safety injection.
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ENCLOSURE
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Table 4.--Zion Emergency Diesel Generator LERs Caused by-Poor Maintenance, Faulty Repair, or Improper Ooeration (1978 - 1980)
E.ent Date Diesel Generator Event
~..~ / 09/78 2B Synchronizing indicator gear was not properly meshed on governor.
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- /16/78 IB Leaking 0-ring in Bearing Hi-Temp Trip Valve.
~7/;7/78 1A Second occurrence of an oil cooler tube leak allowing water to go into lube oile The first occurrence was on 01/16/78.
4
~. i/ ~.1/78 IB Failed to start due to loose bolts on starting air pilot valve.
- i/ ~. ~ /78 1A Rag in oil stra,iner caused low oil pressure.
- /:5/73 IB Leaking fitting in control air pressure system.
i C2/21/79 0
Operator error.
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2A Defective" amplifier circuit in voltage regulator.
On 01/06/78 it was found to l
have burned relay contacts, 5 on 05/17/78 it was found to have a drifted stability circuit, but this voltage regulator was not replaced until 03/10/79.
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Tabl'e 4--continued Page 2 E.ent _Date Diesel Generator Event C3/15/79 1A Rag in pre-lube oil pump strainer.
C5/11/79 0
Screws which hold the starting air valve seat to its retainer were loose.
C3/06/79 2B Low governor oil level allowing air to get into the system.
15/26/79 2A Synchronizing indicator gear was not properly meshed on governor.
C '/02/80 0
Fitting on control air system vibrated -
loose.
- i/24/30 13 Leak in fitting in air supply to fuel shut off.
~. /:7/30 2B Loose screws on overspeed trip lever.---~ -
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