ML19312D503

LER 79-007/01T-1:on 800303,during Review Required by IE Bulletin 79-01,stem-mounted Limit Switches on HCV-864 & HCV-865 Not Found Environmentally Qualified.Caused by Inadequate Design Specs.Switches Will Be Replaced

ML19312D503
Person / Time
Site:	Fort Calhoun
Issue date:	03/19/1980
From:	Mehaffey R OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19312D500	List: ML19312D499 ML19312D503 ML19312D506 ML19312D510
References
LER-79-007-01T, LER-79-7-1T, NUDOCS 8003240514
Download: ML19312D503 (3)

Text

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, LICENSEE EVENT REPORT

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AE80RT QATE i 8 60 61 coCx ET NUve E A e8 EVENT 3 ATE EVENT DESCRIPTION AND PROBASLE CCNSECUENCES h I o 12 I l Du-ine the reviev recuired by I.E. Bulletin 70-013. the stam -r -ted is 4t vi m .c I

[o g 3; j cn HCV-8Ch'and 3CV-865 (charecal filter spray supply) were found to not be enviren- I lo l4 l l mentally qualified. The limit switches provide position indication only and vill l loIsl I not jeopardice valve control or operability. I I

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9 10 11 12 13 18 19 20 SECUENTiAL OCCUAAENCE REPORT 2EV'SION EVENTYEAR R E*CRT NO. COCE TvPE NO.

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47 34 36 36 as 40 43 42 44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h lilol l 2.e limit svitch specifications du-ina initial desiin vere not sdecuate. Tha li.it I li ti j i svitches vill be replaced with enviren=entally cualified limit svitches durire the I i,,7, l 1981 refueling outage. I l

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Ii t il I 90 7 8 9 STA  % POWER CTHER STA".'S 015 C RY OISCO% ERY DESCRIPTION liist lL l @ l nla In l@l NA l l D lAl II Eulletin 79-013 Reviev i ACTIVITY CC TENT

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68 69 l1IIllll1IIIli 30 5 NAME OF PREPARER R. F. Mehaffey , T1 ,ggy,; hMMM@ {

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. LER 79-007, Supple =ent 1 0=aha Public Fever District Fort Calhoun Station Unit-No. 1 Docket No. 05000285

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Attach =ent No. 1 Safety Analysis Ste -=cunted limit svitches on HCV-86h and ECV-865 vere identified.

in the Fort Calhoun Nuclear Station as being unqualified for service within a LCCA environ =ent. The type identified was a Fisher 30h.

In no case vill the failure of these li=it switches cause inadvertant valve operation or prohibit the function of other safety related circuits to perform their designed function. Listed below are the possible failure = odes

- of the limit switches in question. A brief analysis of the consequences re-sulting frc= each =cde of limit switch failure is also given.

Mode 1 --Svitch Shorts - this vould result.in possible indication of both "open and " closed". This =cde of failure in no way inhibits valve opera-tion er control.

Mode 2 - Svitch Open Circuit - this would result in a ec=plete loss of pos-ition indication. Valve operability / control, hcvever, vould not be affected.

Mode 3 - Grounding of the power supply through svitch failure.

The valve circuitry is designed such that the Fort Calhoun instrument buses vill operate with a ground. The circuit design is su;h that only one line to ground (the negative base) would occur. Tha other line is held above grcund by the resistance of the indicatica circuit.

Mode h - Fossible tracking to the solenoid circuit.

First of. all, the probability of this =cde of failure is er re=ely unlikely since the solenoid leads are insulated and separated frc= the limit switches by the " distance of =cunting". Secondly, if the limit switch did happen to track to the solenoid by means of water / saturated steam, the conductivity of this water /

saturated stea= vould have to be near that of ccpper vire. A " ball-park" cen-ductivity figure of 1% boric acid solution (approximately 1800 pp= boric acid)

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is-15 x lo =hos. This number is exceedingly s=all as compared to the con-ductivity of bare copper vire. Therefore, the likeliheed of tracking to the solenoid circuit frc= the limit switch is highly unlikely. Thirdly, assuming tracking to _he solenoid can occur, the current fed to the solen;.1 vill be insufficient to =ake it operate due to the limiting-function of t e li;;ht in-dication circuitry.

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9 LER 79-007, Supplement 1 Ocaha Public Power District-Fort Calhoun Station Unit No. 1

Docket No. 05000235 Attachment No. 1

. ev Analysis Ste:-counted limit switches on HCV-86h and HCV-865 vere identified in the Fort Calhoun Nuclear Station as being unqualified for service within a'LOCA environment. The type' identified was a Fisher 30h.

In no case vill the failure of these limit svitches cause inadvertant valve operation or prohibit the function of other safety related circuits to perform their designed function. Listed below are the possible failure modes of the ~ limit svitches in question. A brief analysis of the consequences re-sulting from each mode of limit svitch failure is also given.

Mode 1 - Switch Sh;rts - this would result in possible indication of both "cpen and " closed". This mode of failure in no way inhibits valve opers-tien er control.

Mode 2 .- Switch Open Circuit - this vould result in a ec=plete loss of pos-itien indication. Valvi operability / control, hcvever, vould not be affected.

Mode 3 - Grounding of the power supply through switch failure.

The valve circuitry is designed such that the Fort Calhoun instrument buses vill operate with a ground. The circuit design is such that only one line to ground (the negative base) would occur. The other line is held above ground by the resistance of the indication circuit.

Mode 4 - Possible tracking to the solenoid circuit.

First ,of all,. the probability of this mode of failure i's extremely unlikely since the. solenoid leads are insulated and separated frem the li=it switches by the " distance of sounting". Secondly, if the limit switch did happen to track to the solenoid by means of water / saturated stes=, the cenductivity of this water /

saturated ' steam would- have to be near that of copper vire. A " ball-park" con-ductivity figure of.1% beric acid solution (approximately 1800 pps boric acid) is 15 x lo nhos. This cu=ber is exceedingly small as compared to the con-ductivity of bare copper vire. .Therefore, the likelihood of tracking to the solenoid circuit from the. limit switch is highly unlikely. Thirdly, assuming tracking to the solenoid can occur, the current fed to the solenoid vill be insufficient to make it operate' due to the lisiting function of the light in-Edication circuitry.

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