ML20037A766
| ML20037A766 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek, Crystal River |
| Issue date: | 03/07/1973 |
| From: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Rodgers J FLORIDA POWER CORP. |
| References | |
| NUDOCS 8003260822 | |
| Download: ML20037A766 (2) | |
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MAR 7 1973 Docket No. 50-302 Florida Power Corporatica ATIN:
Mr. J. T. Rodgers D
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9 Assistant Vice President and g y j\\\\ d
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Nuclear Projoet mangaer F.O. Box 14042 St. Petersburg, Florida 33733 l
Gentlemen Two incidents have occurred at a nuclear power plant that indicate a deficiency in the control circuit design that warrants a review of the control circuits of all facilities to ensure that these types of defi-ciencias do not exist er are oerrected if they do exist. Both ineidaats involved the inadvertent disabling of a component by racking out the circuit breaker for a differvint component. In one ease, this caused the loss of capability to isolate secondary sontavn===t when this espebility 4
was required. In the second case, the rocking out of a breaker for one
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pamp disabled not only the pusp being removed from service but also its redundant counterpart. Both of these occurrences resulted from the use of auxiliary contaats on the movable portion of the aircuit breakers in 5
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the control circuits of other components. When the breaker is racked
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out, the control circuit employing these contacts is opened and may be i
rendered inoperable. Copies of the lic===ee's reports on these two f
occurrences ars==*1amed for your information. The licensee's corrective measures for both of these cases included redesign of the control circuits
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so that racking out the breakers would not render the control cirsuits of.
other equipment inoperable.
h I.: : result of these occurrences, we request that you perform a review of the control circuits of all safety related equipment at the plant to l
assure that disabling of one component does not, through incorporation
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in other interlocking or sequencing controls, render ether components in-operable. All modes of test, operation, and failure must be considered.
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It appears that in the cases cited above, the racked out position of breakers had not been included in the failure mode analysis of these j
aostrol circuits.
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Also, your procedures should be reviewed to ensure they provide that, i
whenever part of a redundant system is removed from service, the portion remaining in service is functionally tested in-aAimtaly after the dis-abling of the affected portion an4, if possible, before disabling of the
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affected portion.
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Florida Power Corporation The results of your revise are sequested within sixty days. This information should be provided with one signed original and thirty-
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nine additional copies.
sinearely.
Original Signed by Albert Schwencer
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A. Schwencer, Orief Pressurised Water Reactors B: ranch No. 4 Directorate of. Licensing Fnelast.res !
Licensee's reports on occurrences cc S. A. Brandimore, Esquire Vice President and General Counsel P.O. Box 14042 St. Petersburg, Florida 33733 DISTRIBUTION-Docket PWR-4 R/F EIGoulbourne (2)
Project Manager i
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Form AEC-SteLRev. 9-53) AECM 0240 o u s coveawe e mnr%,Se'.ca ts71 44s.tes
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if m. 3M y y7fjj Jersey Central Powe'r & Light Company N=:vM.
JADISON AVINUE AT PUNCH BOWL RO AD e MORRISTOWN. N.J. 07960 e 539 6111 April 20, 1972 9e
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6 Dr. Peter A. Morris, Director
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Division of Reactor Licensing United States Atomic Energy Co ission TllAb90 N
Washington, D. C. 20545 e) 3 W
Dear Dr. Morris:
h Subj ect: Oyster Creek Station Docket No. 50-219 Loss of Secondary Contain=ent Integrity The purpose of this letter is to report toyouaviokation of a L1=iting Condition for Operation in that Secondary Contain=ent Integrity was not maintained as required by Specification 3.5.B.l.
of our Technical Specifications.
On April 11, 1972, during perfor:ance of a routine weekly surveillance test of isolation of the Reactor Building and initiation of the Standby Gas Treat =cnt System due to simulated high radiation levels on the Reactor Building Operating Floor and in the Reactor Building Ventilation Exhaust ducts, the supply dampers for the Re, actor Building Ventilation Systes failed to close as required.
As a result of this failure, Secondary Contain=ent was not in effect.
Isolation of the Reactor Building Ventilation System supply damper is initiated by "b" contacts fro = the Reactor Building Ventilation Systc= supply fans, SF1-12 SF1-13, and SF1-14 wired in series. However, l
due to an electrical problem with supply fan 1-13, which resulted in the discovery that the =otor was shorted, its supply breaker was racked-out.
Thus, the logic control circuit for the da=pers was " opened", the nor=al situation with the fans in operation. t! hen the remaining fans were tripped during the surveillance test conducted at 2:00 a.m. on April 11, 1972, the logic control circuit was still open, the da:per g ontrol relays rc=ained de-energized, and the dampers did not close.
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Dr. Peter A. Morris Page II April 20, 1972
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The logic circuit was restored by disconnec:ing the cotor leads from the breaker and racking-in the breaker. At 9:20 a.c.
on April 11, 1972, an operability check of Reac:or Building Isolation was conducted and proved to be sa:isfactory. A caution tag was placed at the fan control switches in the Control Room to notify operators that if a supply fan breaker is racked-out,the Reactor Building supply damper isolation control logic is defeated unless a ju per is installed in the breaker cabinet. A similar caution note is being stenciled locally on the ' supply fan breakers.
As noted in the FDSAR, the pricary objective of the Secondary Contain=ent Syste is to mini =ize ground level release of airborne radioactive ma:erials and to provide for controlled cievated release of the building at:osphere under accident conditions. The contain=ent systc=s, Primary and Seconcary, provide the principle mechanism for
- itigation of accident consequences.
The off-site accident consequences, however, are relatively insensitive to :he Reactor Building in-leakage rate as long as the Standby Gas Treatmen: Sys:c: can =aintain the building a t a vacuu=.
In this particular instance, :he supply and exhaust fans tripped, the exhaust da:pers closed, and the Standby Cas Trea'=en: Sys:em was initiated. With :he above situation. the air supply to the building was not only via the various in-leakage paths but also, and no doub: pri=arily, via the Reactor Building supply da:pers.
Any accident conditions postulated that require sedondary contain=ent in deter =ining environ = ental releases would, under these conditions, have a second path permitting release of the Reactor Building air at approximately a 60-foot elevation.
I.n order to prevent a reoccurrence of this incident _a.
circuit design change vill be i=ple=ented that will per=it a Reactor Building supply fan breaker to be racked-out for =aintenance without defeating the Reactor Suilding supply da:per isolation logic.
Until this design change can be.1:plemented, a s:anding order vill be issued instructing plan: personnel in the appropriate practice :o be followed to avoid defeating the Reactor Building supply damper isolation logic.
Very truly yours, f.
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Ivan R. Finfrock' Jr.
Manager, Nuclear Cencrating Stations IRF/pk p
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cc: Mr. J. P. O'Reilly, Director Division of Compliance, Region I
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Jersey Central Power & Lignt Company N) uAoisON AVENUE AT PUNCH BOWL RO AD e MoRRISToWN. N.J. C796o a 339 8111 October 6,' 1972 J
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Mr. A. Cia =busso g
Deputy Dirce:or for Reactor Projects
,a-Direc: orate of Licensing gg 30Q f
United Sta:es A:c=1c Energy Co==ission k,(
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k'ashington, D. C. 20545
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Dear Mr. Cia =busso:
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Subject:
Oyster Creek Station Docket No. 50-219 Inoperable Standby Liquid Control Syste:
The purpose of this letter'is to report to yo'u an incident that occurced at Oyster Creek on Septe=ber 26, 1972 in which it was discovered that the two pu=ps in the s:andby liquid control syste=
were inoperable at the sa=e time.
At 10:45 a.=. 'on Sep: caber 25, 1972, the "A" standby liquid' control pu=p was rc=oved fro: service for replace =ent of the pu=p packing. The pu=p was taken out of service using Technical Specifica:1on 3.2.C.3 as the basis.
It states, "If one standby liquid control syste= pu= ping circuit beco=es in-operable during the run code and specification 3.2.A is =et,
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. the reactor may re=ain in operation for a period no: to exece //
4 seven days, provided the pu=p in the other circuit is de=en s
- @ g strated daily to be operable". Specification 3.2.A is =et, NY a
therefore, the "A" pu=p breaker was racked cut and the pu=p -Q OI)O M
secured in accordance with plant safe:y procedures. The v F
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was not. co=pleted by the end of the day shif t, and the "A" 6
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pump was left in an inoperable condition. At 4:20 a.=.
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Septc=ber 26, 1972~, the "3" liquid con:rol syste= pu=p was g
to be run to ce= ply with Technical Specification 3.2.C.3.
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k' hen the operator depressed the start button, the pump did I
not start.
An interlock in the starting ci*.cuitry prevents two standby liquid control pu=ps fro = being run si=ultancously.
This interlock also prevents the "3" pu=p frc= starting when the "A" pu=p breaker is in the racked out position. The interlock is cc= posed of a nor= ally closed con:ac: in the starting circuit of each pu=p.
This contact is operated fro a relay in the opposite pu=p circuit. If the "A" standby liquid control pu=p is star:cd. either frc= the control.roo= with the key lock switch or locally fro = the
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push button station, a relay is picked up which opens the normally closed contac: in the "3" standby liquid control pu=p starting circuit which prevents this pu=p from operating with the "A" pump running. The reverse is true if the "3" pu=p is started. The proble developed when the breaker for the "A" pu:p was racked out. It disabled the pu p and a: the same ti=e it physically removed the con:act in the s:arting circuitry fer the "3" pu p which si=ula:ed an,open con:act. This prevented the "B" pu=p from starting.
As soon as :he Shif: Fore =an was aware of the inoperability of both pu=ps, he started a nor=al shut.dcun of the plant.
In the meantine, he received per=1ssion to clear the maintenance safety tags and rack the "A" pump breaker :o its nor=al posi:1
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then ran a successful operabili:y check on the "B" pupp.
The load reduction was stopped and the plant returned to full load.
In order to' preven a recurrence of this event, opera:ing procedures have been changed *so that operabili:y tests of redundant engineered safeguards syste-componen:s vill be made i=:cdiately following any action : hat requires one of the syste:s to be inoperable for =aintenance purposes.
We are enclosing forty copies of this letter.
Very truly yours,
[O7 }.L,'[! % 7 Ivan R. Finfrock, J)/
,Vice President IRF/pk I
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cc: Mr. J. P. O'Rei,11y, Director Directorate of Regulatory Operations, Region 1 O
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