ML19312D506

LER 79-007/01T-2:on 800305,during Review Required by IE Bulletin 79-01,limit Switches on HCV-742A/C,HCV-724 a & 725A Not Found Environmentally Qualified.Caused by Inadequate Design Specifications

ML19312D506
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 8003240518
Download: ML19312D506 (3)

Text

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17 77)

LICENSEE EVENT REPORT

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'4 S0 EVENT DESCRIPTION AND PROSABLE CONSEOUENCES h to12l l During the review required by IE Eulletin 79-013. the limit switches en HCV 7h2A/C 1

[O ;3 ; j (containment purge system) and HCV-72h A and 725A (containment filter unit da=cers) l l o j . ; gere found to not be environmentally qualified. The limit switches crovide valve l lO43; l indication only and vill not jeopardi::e valve centrol or operability. I I

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10: 41I 80 7 8 9 COMP. VALVE SYSTE M CAUSE CAUSE CODE CODE SUSCOCE COMPONENT CCDE SU8 CODE SUSCOCE lot 91 7 8 i s lo l@ 13 l@ la l@ I vIJ l A l t l v l 0 l P l@ I v l@ L-J @

9 10 11 12 18 19 20 CCCUAPENCE REPORT REVISION

_ SEOUENTI AL EVENT VEAR R EPORT NO. COCE TYPE Nc.

LER RO

@ aEPoar l7lO1 1-1 1010171 1/l 10111 17 1 l-l le l 21 23 24 26 27 28 29 30 31 32 22 SHUT 00WN ATTACHutNT NPRO-4 PRIME Coup. COMPONENT ACTION .PUTURE EFFECT MANUPACTURER TAKEN ACTION ONPLANT VETHCO HOURS 24 SU8vlTTE; PURM hu8. SUPPLIE R lJJGl@lJ4 Fl@ lJtC l@ l36Zl@ l 0l 0l Ol 0l l44Y!Q) i Nl@ ,1Al@ 43 l M l 31012 l@

44 47 31 40 42 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h litoll The limit switch specifications durine initisi desisn vera not adecuate. N e lia'it l li ii 1 l svitches vill be reelaced with envirennentally cua11fied limit avdt @ en A ~d~- tu 1

[T TTl I 1981 refueling outage. I li t al l I l

li t a l I 80 7 8 9 ST %PCWER OTHER STATUS SO Y OISCOVERY CESCRIPTION li { s 1 I kl@ l O l O l O l@l NA l l0!@l II Eulletin 70-013 Reviev l t TivlTY CC TENT e:ELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE l l NA l I1 7

Is8 i9d @o OP RELEASE 10 11 NA l 2 l@l 44 45 80 PERSONNEL EXPOSURES NUM8ER TYPE OESCRIPTION l

l i t il 1010 10 l@l z l@l13 NA 80 7 8 9 11 12 PERSONNEL INJURIES NUMSER DESCRIPTION I

li la 8l 9l0 l0 l0 l@l 7 11 12 NA 50 LOSS OP OR DAMAGE TO PACILITY Q TYPE CE SCRIPTION N/

NA l li i s4i 9Iz l@l 7 to so PU8LICITY NRC USE ONLY

• ISSUED DESCRIPTION l2lallZ 144 l NA I ll!!!lllllIl l3 4 68 69 80 h 7 8 9 10 3* 7* M0haff*7 02- d-WO {

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NAME OF PREPARER PHONE:

c iLZR 79-007, Supplement 2 Omaha' Public Power District Fort Calhoun Station Unit No. 1

~

Docket No.~05000285

. Attachment No. 1 Safety Analysis Stem-mounted limit'svitches on HCV-Th2 A and C, HCV T2h-A and HCV-725A vere' identified in the Fort Calhoun Nuclear Station as being unqualified for service within a LCCA environment. The type identified was a MicroSvitch 0TF2-2RN2-RH and OP-AR30.

In no case vill the failure of these 11=it switches cause inadvertant valve. operation er prohibit the function of other safety related cireuits

~

-to perform their designed function. Listed below are the possible failure medes of the limit switches in question. A brief analysis of the conse-quences resulting from each mode of li=it switch failure is also given.

Mode 1 - Switch Shorts - this vould result in possible indication of both

'"open" and "c1csed". This mode of failure in no way inhibits valve opera-tion or centrol.

Mode 2'- Switch Open Circuit - this would result in a complete less of pos-ition indication. Valve operability / control, however, would 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 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 h Possible tracking to the solenoid circuit.

First of all, the probability of this mode of failure is extremely unlikely

. since the solenoid' leads are insulated and separated from the limit switches

'by the " distance.of mounting". .Seccadly, if the limit switch did happen to track to. the ' solenoid by means of water / saturated steam, the conductivity-of this water / saturated steam would have to be near that of copper vire.

A'" ball-park" conductivity figurg of 1". boric acid solution (approxi=ately 1800 ppm boric acid) is 15 x 10 mhos. This number is exceedingly small as ' compared to the conductivity of bare copper wire. Therefore, the likeli-hood of tracking to the ~ solenoid circuit from the limit switch is highly unlikely. ' Thirdly, assuming tracking to the solencid can occur, the cur-

, rent fed to the solenoid vill be insufficient to make it operate due to the licitin6 function _ of .the light indication circuitry.

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LZR 79-007, Supplement 2 . .

. omaha Public~ Power District-

' Fort Calhoun' Station Unit'No'.~'1 Docket No.-:05000285l

~

~

i Attachment No. 2 IFailure Data- '

~ fimilar limit switches .' vere found to be unqualified as a result of the

inspection connected with>IE Bulletin ~.78-oh and LER 79-007, Rev. 1.

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