ML20058H074

Part 21 Rept Re Discovery That Current Limiting Isolation Resistors Not Located in Respective Scram Contactor Boxes as Required by Plant Design Documents.Recommends That Isolation Resistors Be Installed in Scram Contactor Separation Boxes

ML20058H074
Person / Time
Site:	FitzPatrick
Issue date:	12/03/1993
From:	Recasha Mitchell GENERAL ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-93 MFN#-215-93, NUDOCS 9312100271
Download: ML20058H074 (4)

Text

. DEC 03 '93 11:19AM GENE R&AS P.2

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. GENuclearEscrgy Genere!E:ectre Company 175:urmer Anne. Sen ase. C 95125 D e M a 3,1993 PRC9347. DOC l MFN# 215-93 j

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h==f ControlDesk U. S. Nuclost Regulatory hmiani=  ;

Washingma, D.C. 20555 i

Subject:

10CFR Part 21, Reportable OdHan. Inadequate 5=d=

Ibis leuer is to inform the NRC of a reportabic defect per 10 CFRPart 21, as reported to C. Gould the duty of5cer in the NRC operations center by R. C. parh,11. Project Manager, Safety Evaluation Programs onDecember ',1993.

In 1975 GB installad Rasctor Ph System (RPS) scram status indicating lights on a BWR/4's control room panels to show when power is avullable to the scram pilot valvs (SPV) natananda To protect against a hot short conditina the current limiting isolation anslaars for the status indicaring lights should have beca endaard ina* of their i+uv scram contador bases.

In 1993 it was discovered that the currcat I'miHn r f anlahan resistors were not located in their respective scram ennt=< mar boxes (or any = a==tian enetamwe) as reqmrod by the plant design daenments if a hat short across the t=nin=1= of the isolation resistors in cor, Junction with a translant event were to occur, this condition would notjeoparsze the safe shutdown of the BWR/4 plant; however, it is eW that the Mini =n= Critical Power Ratio (MCPR) safety limit would be erreedad wia: this plant technical spacifc=tinn safety limit is reportable even though it does not i+M a miharanh=1 safety hazard.

Very truly yours, b-R. C. Mitchell, Project Manager SafetyEvaluation Programs p esmme cc: C.E.Rossi (NRC-Rochille) ,

L. S. Gifford (GB-Rochille) l l

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9312100271 931203 fi O g 1 i l

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g DEC 03 '93 11:19:ri GENE REAS P.3 i.

ATTACHhENT REPORTABLE CONDITION (i) Name and address of the indMdual or individuals informmg the Commissiore R. C. Mitchell, Safety Evaluation Programs Project Manager, GE Nuclear Energy, 175 Curtner Avenue, San Jose, CA 95125 Ji) Ideen stian of the facility, the actMty, or the basic component supphed for such facility or such activity within the United States which Mls to comply or contains defbet:

A variable worker under contract to GE was recently r: Mewing GE drawings Mag the Reactor Protection System (RPS) output wiring at a B%W4 plant and discovsrud that certain cunent hmsting isolation resistors, installed in 1975 to a GE Field Deviation DLpdaa Request (FDDR),

were not inatad in their respective scram contactor boxes (or any separation enclosure) as required by the plant design dam-ta.

In 1975, the utility owner requested thst GE design a =~H&=6an to their BWW4 plant main control room panels to add scram status indiming lights to show when power is available to the scram pilot valve (SPV) solenoids (see Figure 1). This design change innindad current limiting tanistvm resistors which were maa~*d between the status lights and the points where the SPV soleno&$s are mana*d to the scram contactors. Thers are four resistor and status light mmhinatiana per each of two malenaid logic scram groups (AAB). To protect against a het short at more than coe of the isolation resistors, they are required to be located inside their respective scram contactor aaa=H= boxes. Per the plant's design requirements, the SPV antenaMr are supposed to have separation protection from hat short condrtions which could keep more than one group energized when the scram contactors are de energized. A hot short mndidan in this logic could disable a normal scram signal from the logic group. A bot shcst mad M= in more than one scram group could prevent scram of suf!1cient control rods to bring the core to a suberitical condition in the nosmal time.

"Dr:re are four current ittmtig isolation resistors Irw% SPV se janoid A (Groups 1-4), which are mountad next to each other in Pane 1915, and fbu = = ' 6g T/V solenands B (Groups 1-4),which are mounted next to each other in Panel 917 (see Figutt 2). A hot short across the terminals of the innlatian resistors in either panel on the power supply side could result in aithar SPV scram solennias A or B failure to heim. Both SPV solenoids for each rod group must be do w hes to cause a normal m: ram. If the do cnergized condition went"ad==d. a nonnal scram would not be in& tad upon demand. The backup scram valves would still be availanla to vent off the air header, but this action would be slower than the normal acram.

(iii) TA=#Md= of the firm construcung the facility or supplying the basic - ; =^ which Mis to comply or mn*ains a defect' GE Nuclear Energy, San Jose, Califorms.

(iv) Nsture of the defect or fadure t: comply and the safety hazard which is created or ccr.dd be created by such defect or fkilure to comply:

The potentialfer a hot short to exist at the B%W4 plant is mnsMered a low probability event.

However, if a hot short wers Famd o occur t in cordun tion with a transient r? quiring a scram, the scram would be delayed. This constitutes a limited ATWS event.

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. DEC 03 '93 11:20At1 GENE R&AS P.4 e

For such an event it is expected that the Mninntm Critical Paper Ratio (MCPR) safety limit would be erraMut within 4-5 seconds of the event. Exceeding the plant MCPR tehai=1 p&= tion safety limit is Reportable within the context of 10 CFR Part 21 However, with regant to actual plant and public safety there is no si[miffrant concern nor shamatint safety harard. The safety of the plant would not be jeopardized because bachp scram valves, required by the Anticipated Transient Without a Scram (ATWS) rule would function to bleed off the air header and should terminate the evem within 20 to 35 seconds As a result of the postulated event, the fuel weald rewet and any HaMinr failures would be minor. There would be no sigahat radiation reicase from this postutated transient.

(v) The date on which the iara==tlan of such defhet er fk!!ure to comply was Naat November 30,1993 (vi) In the case of a basic component which contains a defect or fails to comply, the number and location of all so:h components in use at, supplied for, or being supplied for one or more hell! tin or activities subject to the regulatiens in this part:

J.A.FitmatMe (vil) The corrective action widch has been, is being, or will be taken; the name of the individual or orreal*Ian r==aantiW fbr the action; and the length of time that has been or will be taken to enmawa the action:

Because this design un!i&mttan is not a system r quirement for the BWR/4 plant, and the in_alia lan af the current limiting imie$an resistors outside of the scram contactors boxes is inconsistent with the plant design basis regnimnente, GE recommands that the isolation resistors be installed in the scram contacter separation boxes. The utility verbally informed GE that this action was taknn GB provided this same madhtian to one other BWR/4 plant. However, upon review GE rnnehrted that the innlatinn resistors were located in the scram contactor separadon boxes. GE is aware of only one other ut!!ity that installed the scram status lights in their plant (a BWR/2).

However, GE did not supply this mMhdaa and is not aware if the installed configuraten is sinntar to that at the BWR/4 plant. GB is not aware that any other utihties have inarnttad scram status hghts; however, b-ma three plants have this madi&mtian, there is the potential for other utilities to have prmidad a similar madhtian Therefore, GE is lar-iar all GE BWR ntilitica of this condition and reco==>adia! that they review their RPS design to estabhsh if this mad Aenkan was performed at their plant and deta=iae the hiihaad of a bot short cand*a The BWR/4 utility owner iafarm~t the NRC, by Telecon, of this condition and mill prmide the NRC with a completed evakatinn in a Licensing Event Report within thirty days of the telecon.

This informanon was prmided to GE by W. P. Haass of the NRC Reactor Vendor Inspection Branch.

(vill) Any achiev rela:ed to the defect or failure to comply about the factlity, activity, or basic s- .=*

that has been, is being, or will be given to purchasers or licensees.

It is GE's recommand=Han that all BWRutilities review their RPS design to estabhsh if this madhtien was performed at their plant and detennine the lihiiha~i of a hot short eaaditian i

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i DEC 03 '93 11:21R1 GDE R&AS P.5 ~ j

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