IR 05000409/1985019
| ML20136H394 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 11/19/1985 |
| From: | Boyd D, Eng P, Ring M, Villalva I, Joel Wiebe NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20136H356 | List: |
| References | |
| 50-409-85-19, CAL-85-14, CAL-RIII-85-14, NUDOCS 8511250097 | |
| Download: ML20136H394 (11) | |
Text
October 23, 1985
SUBJECT:
DAIRYLAND POWER COOPERATIVE LA CROSSI BOILING WATER REACTOR (LACBWR)
PROVISIONAL OPERATING LIC2NSE NO. DFB-45 manama! TO CONFIMATORY ACTION LRTTER Reference:
(1) Letter Emppler to Taylor, dated October 23, 1985
Dear Mr. Esppler:
You sent us a Confirmatory Action Letter regarding an apparent improper response of the reactor protective system (Reference 1). We have reviewed the items listed and our response follows.
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M 11mf1 Clasanct a thoraangh misw to Atarnise if a trip aismal actually man moeived by the nonctor Protection Spute (ME).
RfC RESPONSI A thorough review has been conducted. It has been concluded that a scram signal was not received. An alaru signal was received which gave one visual i
indiestion of a possible trip condition.
i M IfEV 2 1/ seat a alamm1 aus receive 4 hearafar adtr the emotimJ sed Almiled to autamuticelly insert.
DPC B5P0153 N/A
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I OCT 24 '85 11815 P83 N4 Ne 'P OCT
'85 11821 1110 P03
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ATTACHMENT 1 October 23, 1985 Mr. James G. Reppler I.AC-ll211 U. S. Nuclear Regulatory Commission
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page 2
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Region III
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M 11St 3 i
If such a trip algael non not noeined, determine edly the annunciater ame j
actiewted.
DPC RESPONSE Due to an apparent failure of an oscillator circuit on the trip stage of NI-6 that should have ensured that both the alors and trip relays actuated at the same time; the annunciator canne in approx. 'Fi power before the trip signal actuated. A very slow increase in power to approx.1104 indicated on the 150 x 10-st scale, in conjunction with a possible noise spike of a few percent activated the annunciator but not the trip. We were able to duplicate the separation between the annunciator and the trip releys many times, with the
"same results. This has been observed by the NBC Besident Inspector and the personnel sent fram Negion III.
M11W4 Betermine anbet conned the signal that nuclear inutnmentation sheerred and entr nuclear imetriaaset channel nam 6er 5 aan not aWiscted.
DPC RESPONSE At this power level (10-st) there was a spread of 64-10% between NI-5 and NI-6.
The 0500 readings on 10/23/86 abowed NI-6 to be at 664 and NI-6 to be 82% on the 150 x 10-** scale. This spread would allow NI-6 to reach an actuation condition without NI-5 reaching an octuation point.
M5 Akistain all affected equismaet minted to the naector ypotection craten is auch a naamar that it can anelly be knpt er placed in.the *an fened" Sarafare, tate no action atlet meeJd duetswy er comes te he cuadifiae.
last, (other than nacaesary to protect the health and anfety of the public)
any evidance adtiet amald he needed to investigste er nacenetruet this event.
DPC RESPONSE Although some minor adjustment was done on NI-6, it can be placed in the as-found condition. No further action will be taken on the dresser, pending NRC concurrence of the course of action deessed necessary.
M 11EV 6 Arrieur eqparater actione tahan Jamediately following" his reansmitian af the f>llure to trip and deteraise if thane actione ante in accernemoon erith your i J and polician (specifian117, determine a6y the centrol roer naare manualir lacerted rather than by ineecting a amenal trip aisual.)
OCT 24 '85 lit 16 P84
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'85 11:22 1110 PO4
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ATTACHMENT 1
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Mr. James G. Emppler October 23, 1985 U. S. Nuetear Regulatory Commission LAC-11211 Region III page 3 DPC MSPON$E The operator's indication of an apparent trip condition was annunciator D5-4, his power level indication was at 1104, which is well below the nominal scran point of 115%. Be immediately reduced power to sub-critical by inserting #1 control rod. The ATWS procedure allows either a manual scram or control rod insertion.
(Ref:
IACBWR Op. Manual Vol. I, Sec. 4.12.) This was accomplished.
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t A forum 1 report of posur fladians and casc[uskaan edil be sa6mittad to the narico III office withis.N dow.
BPC MSPONSE This letter constitutes the requested response.
M EMV 0 hir fkarther nederstand that startap will mot occur sutil metherisatlan to rautart la obtained than the nnglamal khalaistrator er his daniginee.
DPC M SPONSE The investigation has been discussed with and testing perforised under the cognizance of NRC representatives. Restart will await authorization by the Regional Administrator or his designee.
Very truly yours, DAIRYLAND F0WER COOPERATIVE James W. Taylor, General Manager j
FL:JDP:IMK:dh cc - Document Control Desk U. 5. Nuclear Regulatory Casamission Washington, D. C.
205h5 NRC Resident Inspector J. Stang, NRC Project Manager M ET C 118 30
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