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wAssimoTow, o.c. sous April 3.'1973 l Dot.ke r. 'No. 50-219 t
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Jersey Central Power and Light Company
' ATTN:
R. H. Sims, Vice: President Madison Avenue at Punch Bowl Road
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Morristown,;New Jersey 07960 l'
Gentlement To assure that any significant release of fission products is-retained within the. containment system in the event of a design basis accident such as a loss-of-coolant accident, isolation I
valves have been installed in the main steam line of boiling water reactors (BWR). To achieve high reliability of containment
. isolation ~, two valves are installed in series in each steam line.
j Proper closure of either of the two valves will prevent release of fission products by this route from exceeding 10 CFR 100 To achieve'the. required i
guidelines in.the event of an accident.
high rrliability, it is.ecessary_that each valve have a high n
reliability.
A review of the reliability to close on demand of the main steam isolution valves (MSlVs) for the larger BWRs has been conducted.
It is concluded that supplemental action is required to improve the reliability of the MSIVs to close on demand.
3 A summary of the failures of the MSIVs is included in Attachmentf Experience at thc'four older BWRs is not included because o A.
A review of the.significant' differences in valve configuration.
the sixteen reported _ failures to close shows that in all cases, except one, the failures were caused by a sticking pilot valve in the MSIV pneumatic control system. Events have also been reported of slow MSIV closure and malfunctions during exercising which have been caused by sticking pilot valves.
It is our understanding that the sticking pilot valves'are all cf the same design and provided by one vendor.
Based on the reported experience, correction of the cause'of pilot valve sticking should be a first priority' item in improving MSIV closure reliability.
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1 2-April 3,1973 Corrective action has been taken at some reactors to eliminate some of the causes of pilot valve failure.
During 1970 and early 1971, Dresden 2 sustained nine occurrences of MSIV failure to close. The corrective actions taken at Dresden 2 and 3 are described in detail in Attachment B.
In summary the following actiors were implemented:
1.
The clearances between the piston and the cylinder walls of the pilot valve were, increased.
2.
The operating gas was changed from air to nitrogen on both the inboard and outboard valves to compensate for the higher leakage of gas into the drywell caused by item 1.
Changes were made in the gas handling system to improve gas I
quality. The pilot valve temperature environment was found to be in excess of the design temperature and was corrected.
In addition, a change was made at Dresden 2 and 3 to the MSIV slow closure system such thct the fast cloaure pilot was exercised during each twice-weekly exercising of the MSIVs. In the two-year interval since the above changes, no failures of the MSIVs to close have been reported.
Based on information provided by telephone, all but one of the large operating BWRs have pistons in the pilot valve with increased clearances, and all but two have converted the operating gas, on at least the inhoard valves, to nitrogen.
It may be noteworthy that all four of the failures were of outboard valves which were operated by air.
most recent We conclude f rom the experience to date that poor quality op erating gas is the most probable cause of most of the MSIV failures to close. A temperature environment higher than the design rating of the pilot valve cannot be climinated as a possible contributing cause. Based on the experience to date, we conclude that design improvements to eliminate pilot "alve sticking are necessary at most BWRs to assure that MSIV valve closure reliability is improved to the level required by the safety function of this equipment, r
It is requested that you provide a description of any changes planned for your reactor to upgrade the reliability of MSIV closure.
If no l
changes are planned, provide a discussion of the features of your system which you believe causes it to be more reliable than is indicated by the general experience of Attachment A.
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4 April 3, 1973 To aid in our current and future evaluation o' MSIV performance, the following information is requested:
The minimum clearance between the pilot valve piston and a.
the pilot valve cylinder.
b.
The specifications for the cleanliness of the MSIV operating gas (es), a description of the means for achieving these specifications including the particle size rating of particulate filters, and the means used to monitor that the specifications are being achieved.
The temperature environment of the MSIV pilot valves.
c.
d.
A description of the preventive maintenance program for the MSIV pneumatic control system.
The above information is req'uested in 90 days and should be submitted as 1 original and 39 additional copies, i
Sincerely,
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l Donald J.'Skovholt Assistant Director I
for Operating Reactors Directorate of Licensing
Enclosure:
1.
Attachment A - MSIV Failure-To-Close Experience 2.
Attachment B - Corrective Actions
' to Assure MSIV Operability cc: GPU Service Corporation Ocean County Library ATTN:
Mr. Thomas M. Crimmings, Jr.
15 Hooper Avenue Safety and Licensing Manager Toms River, New Jersey 0875 26,0 Cherry Hill Road Parsipanny, New Jersey 07054 G. F. Trowbridge, Esquire Shaw, Pittman, Potts, Trowbridge & Madden 910 - 17 th S tree t, N. W.
l Washington, D. C. 20006 I
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j ATTACHMENT A MAIN STEAM IS01ATION VALVE FAII}T;E-TC-CLOSE EXPERIENCE i
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date Reactor Number of Failures Component Failure 5/8/70-Dresden 2 4
Pilot valves 12/4/70 'Dresden 2 4
Pilot valves 1/22/71 Dresden'2 1
- Pilot valve f 8/1/71 Millstone /
1 Pilot valve 11/16/71 Oyster Creek 1
Dash pot
$/13/72 Monticello 1
Pilot valve 11/15/72 Quad-Citiesi 1
Pilot valve 11/29/72 Pilgrim 1
Pilot valve 1
Pilot valve 12/3/72
.0yster Creek 12/29/72 Oyster Creek 1
Pilot valve l
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ATTACHMENT B.
v REPORT NO. 7-
.p CORRECTIVE ACTIONS ~TO ASSURE i
MAIN l STEAM LINE ISOLATION VALVE OPERABILITY-March 17, 1971 t
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Commonwealth Edison Company l
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'l D-2' REPORT NO. 7 COMMENT-A detailed report of corrective actions taken to assure main steam line isolation valve operability.
RESPONSE
Background On several occasions between April 30, 1970 and February 1,1971 the main steam isolation valves (MSLIV's) installed in the Dresden 2 '
Nuclear Power Plant failed to operate due to sticking of the pneu-matic valves which control the flow of air to a cylinder operator to open and close the MSLIV's.
The pneumatic valves in'use during April and May 1970 had small l
clearances and were highly sensitive to contaminated air and exces-sive heat. Test thermocouples installed on the outside of the pneumatic valve housings showed that in operation the valves installed in the drywell reached approximately 129'F and valves in the steam tunnel reached 175'F.
Inspection of the valves showed the lands of the spools were significantly discolored and coated with a varnish-like substance. All spools were very sticky in the sleeve.
When the spools were washed in solvent and cleaned up, they freed up considerably, but not as free as manufacturer repre-sentatives recommended for a normal spool and sleeve. Therefore, it was. concluded that two problems were being encountered.
- First, 4
there was contamination getting into the valve in sufficient quantity to cause the spools and sleeves to stick and bind.
In addition, some of the spools and sleeves were oinding mechanically because'of the heat.
Either one of the two problems would render a valve of the type used at that time inoperative. As discussed in the Special Report on the June 5 incident, Supplementary Informa-tion, steps were taken to replace all the pneumatic valves with higher clearance type valves and also additional air conditioning equipment was added to the steam tunnel to reduce temperatures in the area of the valves.
In early December 1970 four main steau isolation valves failed to close and one closed out of tolerance <!uring a schedule surveillance test. Upon inspection of aa pilot vaives the same sort of.contamin-ation on the spool caused tne sticking. The source of tne contamin-ation has been traced to the air supply compressors. These are oil lubricated compressors. After'a significant period of operation the oil leaks into the air supply.
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rep 0RT NO. 7 Corrective Action i
l The following corrective actions will be taken to eliminate the MSLIV i
actuation problems:
1.
The clearance between the sleeve and spool has been increased-and additional air cooling has been installed.in the steam tunnel i
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to eliminate binding caused by high temperature.
2.
The instrument air system for both Dresden 2 and 3 has been.
thoroughly cleaned to avoid entrainment of dirt and oil.
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3.
Three different plans of action are being undertaken to ensure oil and other contamination are not introduced back into the MSLIV-pneumatic supply.
a.
The valves inside the drywell will take their supply from a pumpback system. This system consists of two air com-i pressors, filters, separator and dryer, a 250 gallon receiver, and associated piping, valves, controls and instrumentation. The drywell pneumatic supply system takes suction from the drywell atmosphere, compresses and cleans the gas and stores it in the 250 gallon receiver at a nominal 100 psig. The receiver discharges to.the. equipment in the drywell.,ich require motive gas. This system provides a source of clean gas for use in all pneumatic equipment thus i
limiting the effects of dirt and oil on the operation of MSLIV's. This system is being installed during the current outage..The system will be connected to the presently installed pneumatic system to supply all the equipment c
within the drywell requiring motive gas. The back up supply is nitrogen from the Drywell Atmosphere Make-Up System. A copy of the P&ID for the Drywell Pneumatic Supply System is attached.
b.
As an interim solution the MSLIV valves located inside the steam tunnel will take their motive supply from four liquid nitrogen storage tanks. Tne liquid nitrogen system provides a constant regulated pressure of 115 psig to the supply system. - The system is capable of continuous delivery of i
800 scfh or.1850 scfi._ Tor si. ort periods at pressures up to 150 psig.
Each station comprises of:
- 1) filter,'2) a fin air vaporizer, 3) console with controls, 4) appropriate valves l
and pressure regulator, 5) liquid nitrogen tanks each having 3650 scfh capacity', and 6) pressure switch and low pressure annunciator in the control room.
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D-2 REPORT NO. 7 This system will be replaced by an oil-free,1on-lubricated compressor.
The instrument air will be separated from the service air compressors and two non-lubricated compressors, redundant filters, dryers, air receivers, installed into the instrument air supply to form a com-pletely separated oil-free system. The Dresden 2 and 3 instrument air supplies will be identical and " cross-tied" to provide redundant systems for both plants (each system has the capacity to supply both units). As the source of oil was being introduced into the system by the oil lubricated compressor, the installation of the new com-pressors will eliminate the source of contamination.
7; It is concluded that the corrective action described above will elim-inate any further MSLIV problems. This conclusion is substantiated by the number of BWR's in operation with this type of valve without any actuator problems. The only difference between the successfully operating valves in these BWR's and Dresden is the air supply system.
After the completion of the corrective action described above, the plant will return to a normal technical specification surveillance program.
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Jersey Central Po[ wet & Light Company f
madison AVENUE AT PUNCH OoWL Ro AD e MoRRisToWN. N.J. 07960 e s39 6ti t -
April 3, 1973 Fir. F. E. Kreusi, Director Directorate of Regulatory Operations United States Atomic Energy Commission i
Washington, D. C. 20545 i
Dear Ftr. Kreusi:
Subject:
Oyster Creek Station Docket No. 50-219 t
Quarterly Personnel Exposures The purpose of this l'tter is to advise you that two employees c
assigned to the Oyster Creek Station have possibly received whole-body exposures in excess of 3 rems during the first quarterly period of 1973.
This report is being submitted in accordance with 10CFR20.405.
In the interest of being conservative, this exposure is being reperted a:: :: hole-body exposurc at this timu. The exteni of the exposure-range from. 3.140 rem to 3.290 rem based upon film badge results. The exposure of each individual by name is listed in Attachment A to this f
letter.
Each individual has been given notification of his exposure.
The exact cause of the overexposure cannot be determined with any degree of certainty since in cach case the violations were discovered upon receipt of film badge results which are analyzed monthly.
Each individual had been engaged in various activitics throughoat the month, therefore, no direct correlation can be made.
It bears mentioning, however, that as a general rule, neither of the individuals would have worked at their jobs in radiation fields foi any length of time without ei her assisting, hiu or at 1 cast one other individual being present, t
working with him in some manner. Thus, it would be expected that more i
than one individual would be exposed to the same radiation intensity.
Yet, in the case of the excessive beta exposure, no other individual received any exposure to beta radiation during the period of time in qacstion.
In the cese of the second individual, the discrepancy.between the film badge results and self-reading pocket dosimeters was nearly twic(
as large as that noted for other individuals.
The reported exposure provided by our film badge service is currently under investigation by na outside consultant.
Results of the invertigation should oc availaole within sixty days.
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L-I' Mr. F. E. Kreusi b
Page II April 3, 1973 Further strengthening of our personnel exposure accumulation is indicated by this event.
More frequent "im badge exposure data will be collected in the future as an inc.ividual epproaches quarterly whole-body exposure limit as follows:
Accumulated Quarterly Film Badge Exposure Range Reading Frequency 0-1.000 R Monthly 1.000-1.750 R Semimonthly 1.750-2.500 R Weekly 2.500-3.000 R Daily It is believed such practice will prevent further minor overexposures similar to those that have been reported to your office over the past year.
Very truly yours, 7xuze1 L,u$v 0
f) a Donald A. Ross
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Manager, Nuclear Generating Stations
'pk Attachment
,cc:
. J. P. O'Reilly Mr. S. W. Porter J
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MADISON AVENUE AT PUNCH DoWL Ro AD e MoRHisToWN, N.J. 07960 e 539 6t t i April 3, 1973 Mr. Frank E. Kreusi, Director Directorate of Regulatory Operations United States Atomic Energy Commission Washington, D. C. 20545
Dear Mr. Kreusi:
Subject:
Oyster Creek Station i
Docket No. 50-219 Additional Information/Per;onnel Overexposures
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This letter is in response to your Janua.*y 31, 1973 letter to Mr. Ivan R.
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Finfrock, Ji. requesting additional information regarding the results of our investi-i Eation into the overexposures reported to your office by 1ctter dated August 10, 1972.
The special General Office Review Board investigation determined the major factors leading to'this incident were the unexpectedly high radiat.4on levels encountered 1
and the unanticipated repair work associated witn tne plant shutdown. Tne incident resulted from the desire of some personnel involved to insure that the work required was properly performed to insure satisfactory performance of the plant and from the 7
lack of.a specifically defined and enforced radiation exposure limit (below the
- allowabic level) at which the men should not have been permitted to work in radi-ation areas except under very close control.
The action taken to prevent similar exposures from reoccurring were as 4
follows:
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No person will be permitted to incur doses in excess of 2500 n. rem whole body per calendar q arter without written authorization from *he Manager, Nuclear 3
Generating Stations. Persons so authorized will be subject to special control while accumulating any additional exposure.
2.
A daily report, current as of the previous day, will be issued by the radiation protection group at Oyster Creek showing accumulative quarterly exposure of all personnel for which such exposure execeds 1.25 rem whole body. The report will be dist ributed to all forcmen, supervisors, the station superintendent, and the Manager, Nuclear Generating Stations..It contain's the man's name, position, and controlling record of exposure. Station operating procedures have been changed to reflect all of the above iter.is.
.Very truly yours, 3
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LM Donald A. Ross Manager, Nuc1 car Generating Stations nk-
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Mr. S. ii. Port er F 3 O F / 2 c a p s _.
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