ML18057B188

LER 91-011-00:on 910627,determined That Core Exit Thermocouple Electrical Connectors Not Fastened to Supports, Per Seismic Analysis for in-core Detectors.Caused by Inadequate Procedure.Procedure Revised.W/Undated Ltr

ML18057B188
Person / Time
Site:	Palisades
Issue date:	07/29/1991
From:	Hillman C, Slade G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-011, LER-91-11, NUDOCS 9108050222
Download: ML18057B188 (5)

Text

e.

consumers Power G BSlade General Manager POWERINli -

MICHlliAN"S PROliRESS

• Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKtT 50-255 - LICENSE DPR-20 '~ PALISADES PLANT -

LICENSEE EVENT REPORT 91~011 - SEISMIC QUALIFICATION OF QµALIFIED INCORE DETECTOR ELECTRICAL CONNECTORS. . .

Licensee Event Report (LER)91-011 is .attached. This event is reportable to the NRC per 10CFR50.73(a)(2)(ii)(B). .

.£///3,41'~-**

Gera 1d B Slade General Manager CC Administrator, Region III, USNRC NRC Resident Inspector - Palisad~s Attachment

• ,; :I. (> :::: (> :~; ::) ~? ~'..:::~

F' G~: AD Cl Cf<

'~:

A Cll/IS ENERGY COMPANY

U.L llUC\Ull ltlOUU.TOltY ca

"""'°"ID Oll9 NO. J110~1CM

."°"

IX,lflU: 11'1 -

LICENSEE EVENT REPO.RT (LERI.

l PACILITY IUMI 111 DCICKIT - I I Ill I **

Pal:isades Plant 0 . 11 I 0 I 0 I 0 12 15 I 5 , IOF 0 I 4 TITLI I.el SEISMIC QUALIFICATION* OF QUALIFIED INCORE DETECTOR ELECTRICAL CONNECTORS MONTH IVINT ~Tl DAY Ill YIAll YUiii Liii NUllUll Ill t:t **~=~Al. itj = lolONTH

.llDOlllT llATI 111 DAY YIAl'I N/A OTMlll PACILITIU ..vo&.VID

'ACll.ITY N&MU m

OOCltlT llUMUlllll 0111010101 I I 016

• ~

7 9 1 9l 1

- ol 1I1 - .ol o d 7 219 91 1 N/A o,1 1o 1 oio1 I <' I Of'lllATllllll TlUI llDOltT * .,_ITTID PU"8UANT TO TMI lllOUlllllllNTI Ofl 10 CPll. §: I~ - er - .,, lfle 1e1-. 1n1

.,__ llllCIDllll

_ _ _ _ _.i..t~

..... I N llll~I

........... IJ -- llll ...Cel

• .ace.1111 -- *.711allllli.I

• .ni.11111t1 LIVIL . -

1101 1 I n In *.-c.1111111

- 10.*1IC21 IO.nlalWClll OTMlll IS-1'>/ 111 A - . r

• 1r;aw==.:::

- ..._.,,. ,,, Tnr. Nlfl:*'-

I0.7:1111CZICll I0.711alCllllllllW >>MI. .

i.

a;,_

I0.71c.ICllCll I0.7SlllCllCNll LICINlll CONTACT 'Oii TMll Liii 1111

-- I0.71Cllllllltlllllll I0.71C111Clit*I NAMI TILIPHONI NUMllll AlllA COOi Ciis T Hillman, Senior Engineer 6 11 I 6 7 16 Ji. I - 18 I 9 I 1 13 CAUll IY.ITIM CO"'°NINT D I IP I ISIXRl21210 N I I I I I I I I I I I I I I I I I I I I I IUW\,IMINTAL lll'°llT IXl'ICTID il41 MONTH DAY VfAll t Yll 11' ,._, - ,,;,..t:TIO JIJllltsSiON DATii I I I AUTllAC'T IUmlf

• 1<<10 -

• I.e. ..- * ; - - , fl'- Ii,.._ ry_.,.,, litt9/ 1111 ABSTRACT On June 27, 1991, at*0900 hours, with the plant operating at 1003 power, it was determined that the Core Exit Thermocouple (Incore Detectors) electrical connectors were not fastened to their supports as intended in the seismic *

• analysis for the incore detectors. An interim operability justification for continued riperation has determined the seismic response to be negligible and the present.configuration acceptable,

-Th~ cause of the event was an i~adequaie procedure.

Corrective action for this event includes providing new incore instrument flange lifting posts to replace those which have been broken; revising /

technical specification surveillance procedure to incorporate the requirements to attach the incore instrument cable to the support plate following re-connection of the electrical connectors; and revising permanent maintenance procedure to incorporate the requirement to attach the reactor vessel level and core exit thermocouple instruments to the support plate following the re-connection of the electrical connectors.

This event involved the failure of the attendant seismic support for the incore electrical cable.

NllCf_ . .19-131

• . U.I NUCLEAll ~EwULATOAY CC*MIDIOff LICENSE ENT REPORT (LER) TEXT CONTINUA N Al'PROVEO 0.1.111 "9 3150-01~.

EXPIRES 8/J1115

'ACILITY NAMI 111 L!ll NUMelll Ill 'AOI Ill

.. * *:*: SIQUl ... TIAL ::*: llllVISION

.-*_::: NUM a* *. NUM 1111.

T'EXT ,,, _ _ _ _ _* --NlfC . . . . . .,

Palisades Plant 1171 05000 255 1 - 1 1 ~ 0 0 0 2 OF 0 4 EVENT DESCRIPTION Discussion On June 27, 1991, at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, with the plant operating at 100% power, it was determined_ that the Core Exit Thermocouple (Incore Detectors) electrical connectors were not fastened* to their supports as intended in the seismic analysis for the incore dete~tors. An interim operability justification for continued operation has determined the seismic response to be negligible and the present configuration icceptable.

• Following the 1990 Refueling Outage the refueling contractor discussed with CPCo the desire to have the electrical connectors to the incore detectors shortened to make their installation easier.* During these conversations the

• design of the support post was also-discussed since it too may require modification to accommo~ate the shorter electrical connector. During subsequeht conversations between CPCo and the refueling contractor, held June 7, 1991, it was determined that at least two of the posts which are used as lifting lugs for the incore instrument flange [IP;SX] were broken. These

~osts are also used as seismic supports which secu~e plates and clips f6r the*

incore instruments [IP;XI] and thus the core exit thermocouples [IP;TI] just below the elect~ical connector. The refueling contractor field engineer was unaware that these posts were also required to support the incore instrument electrical connectors and did not report this event until after the 1990 Refueling Outage had ended. The refueling contractor field engineer reported the broken posts only as needing repair to provide for lifting the flange.

With these posts broken, no support is provided for the core exit thermocoupJe electrical connectors. Thus, the core exit thermocouples were in an un-

• analyzed condition in terms of seismic qualification.

A corrective ~ction document was -initiated and an evaluation of the current seismic response of the incore detectors was performed. This evaluation .

determined the seismic response to be negligible and the present configuration

~acce~table. The corrective action document was returned to *the Palisades

• Corrective Action Review Board (P-CARB) for*post evaluation review on June 27,

.1991. It was during the P-CARB review that the condition was determined to be reportable to the NRC. Consequently, on June 27, 1991, at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, the NRC was notified of the condition and additional corrective action was initiated.

Subsequent discussions with the Instrument and Control (I&C) technicians, the work group responsible for incore instrument re-connections, indicate that the I&C technicians do not place the incore cables in the clips as p~rt of their re-connection sequence for the incore electrical connectors. Thus, the majority of the qualified core exit thermocouples are probably not supported.

as intended in the seismic analysis. *

.l

~ .. c*-=Of'm JM.&

U.I ".UCUAll ~EGULATORY CC*MIGIO..

lll-8Ji LICENSE ENT REPORT (LERI TEXT CONTINU ON ~PPROVEO OMll l'jQ 3150-0I°'

E~PIRES BIJI 185 PACILITY 'NAMI 11 I ' DOCKET NU. .111 121 Liii N~lll 111 ~AOI Ill.

llQUINTIAL. ::*: flllVlllON NUM I~ .*, NUM I~

Palisades Plant 05000 25591-01 1-0 3 OF 0 TEXT,,, _ _ * - - * - - N l l C ,_..,..,, 1171 Historical Background During the 1985 Refueling Outage, 16 of the 43 core exit thermocouples (which are an*integral part of the incore instrument} were upgraded to Class IE to meet the requirements of NUREG-0737, Item 11.F.2, "Instrumentation for the Detection of Inadequate Core Cooling." Credit was also taken for the core exit .thermocouples meeting the requirements of Regulatory Guide (RG} 1.97, "Instrumentatirin for Li9ht-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident~" Both NUREG-0737 and RG 1.97 required that core exit thermocouples be environmentally and sei~mically qualified.

• The sixteen qualified core exit thermoco~ples were procured from Combustion Engineering which, in tufn, .provided documentation ~upporting the seismic and erivironmental qualification of the instrument. Seismic qualification was ..

based on the electrical connector being physically supported. This support is required to prevent motion of the connector and attached cabling from putting stresses at the point where the electrical cable and its flexible sheath enter the' instrument flange seal _plug. Undue stresses at the seal plug could result in cracking or breaking the cable sheathing and enclrised mineral insulat~d

. wire..

• CAUSE OF THE EVENT The cause of the event was an inadequate procedure.

Installation of the incores is controlled by Permanent Maintenance Pr.ocedure RVG-M-5, "Reactor Head Installation." This procedure instructs the l&C group to re~connect the incore. ele~trical connectors. It also instructs the I&C group to attach the .incore cables to th~ support clips. However, the l&C group installs the incores in accordance with the instructions provided in Technical Specification Surveillance Procedure RI-80, "Incore Monitoring System Calibration 11 , which does not instruct the l&C group to attach the incore cables to the cable support. Had the llC installation procedure, RI-.

80, clearly identified that the incore cable was required to be attached to the support plate, this event most likely would not have o~curred.

The refueling contractor field engineer also verbally identifi~d that several.

of the spring clips on the support plate were missing or broken. A review of the design of the existing support plate and spring clips indicates that the design is susceptible to breakage. Two of the support plates were re-designed for the two instrument flanges which contain the reactor vessel level*

instruments. This new design has a support plate which is scalloped to hold the incore and/or reactor vessel level instrument with a. "radiator hose" type clamp holding the instrument cable in place. The refueli~g contractor has

""C *OllM lMA

• 111-tll

LICENSE-ENT REPORT ILER) TEXT CONTINU N EXPIRES 8/Jl 115 . '

'ACILITV !llAMI !11 . DOCKET. NUMllUI r:rr Liii NUlllelll Ill , .. 01 131 Palisades Plant

• 0 I5 I 0 I 0 I 0 , . 2 1 5, s 91 1 - 0111 1 - 0 I 0 Q 14 OF 0 I4 TECT 1/f , _ - 9 ,..._, - - /WtC 1-lm.e'oi 1171 stated that the incofe cable connections to these two support plat~s were properly made up and thus it is believed that at least three of the qualified cor~ exit thermocouples are properly supported.

ANALYSIS OF EVENT An operability determi n*at ion was made as part of the corrective action which

.documented this event. This event is considered -reportable under 10CFR50.73{a)(2)(ii)(B) as a condition that is outside the design basis for the plant.

• CORRECTIVE ACTION

1. Provide new incore instrument flange lifting post to replace those which have been broken. Consider use of a scalloped support plate and "radiator hose" arrangement to replace the existing support plate and spring clips.

(1992 Ref out)

2. Revise Techriical Specification Surveillance Procedure Rl-80 to incorporate the requirements to attach the incore instrument cabl~ to the support plate following *re-connection of the electrical. connectors. (01/30/92)

3. Revise Permanent Maintenance Procedure PCS~I-49 to incorporate the requirement to attach the reactor vessel level instrument to the support plate following the re-connection of the electrical*connectors. -

(01/30/92)

ADDITIONAL INFORMATION None