ML19326A562

LER 77-100/03L-0:on 771201 & 05,source Range Neutron Detector NI-1 Indication Dropped to Zero & Returned to Normal Operation W/O Assistance.Cause Unknown.After First Failure,Detector Replaced & Retested

ML19326A562
Person / Time
Site:	Davis Besse
Issue date:	01/05/1978
From:	Hitchens D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A553	List: ML19326A551 ML19326A562 ML19326A563
References
LER-77-100-03L, LER-77-100-3L, NUDOCS 8002040733
Download: ML19326A562 (3)

Text

.. ..... . . _ _ . . . _

NRCFORM366 O

LICENSEE EVENT REPORT (777)Q / x

~

(TLEASE PRINT OR TYPE ,.a.L REQUIRED INFoRMATloN)

CCNTROL SLOCX: l i

l l l l l

.,l h l lg 7

o O luggs3gE a i DGagf 'a ! s i .at i@l o l oUCE'.Si 14 l - l r.W.'es olo r4 l n l P l v l - l ouCENSE 23 l 3 l@26[4ltl TvPE JJ il C Atit T soltl@l CCY "5

I3lil

• , 4 l6J L !@l o f 5:;oGKET 61 l o %...*6&R f - 1 o f 3146dl 6 l@l 1 l 210 l t l 717

' 4 EV ENT cArg ;4 75 l@l REPCRT OATE1 ! 2 80 I 2171 - l EVENT DESCRIPTION AND PRCSABLE CCNSECUE'JCES h I o 121 1 On two occasions, 12/1/77 at 1455 hours0.0168 days <br />0.404 hours <br />0.00241 weeks <br />5.536275e-4 months <br /> and 12/5/77 at 0115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br />, Source Range l g

g ; Neutron Detector N1-l's indication dropped to zero and returned to ncr=al operation /

,y,,, ;

indication by itself. Both occurrences placed the unit in Action Statement 5 of j

, Technical Specification 3.3.1.1. There was no danger to the health and safety of the ;

,,,g,

,og, g.public or unit personnel. The redundant Source Range Detector NI-2 was operational (NP-33-77-100) j

o,7; l and in service throughout these occurrences. ,

~

l lo ta l I so 7 8 9 "

sos'E ##$0 co suscEE couPoNENT ccoE Sua C c'e'E SUSC 3E lo l 91 l Il Dl@ ]Q l X l@ lI lN lS lT lR lU j@ l El@ l Zl@

12 13 18 19 20 7 8 9 10 11 SEQUENTI AL, OCCURRENCE REPORT REVl53oN REPORT No. CooE TYPE No.

L ag h yu'ERtRo u

EVENT YEA R 17 l7 l l-l l1l6l0l l/l l6 l3 l l Ll l-l y 32, 23 24 26 27 28 29 30 33 21 22 T M TH hours 22 sus t PoR s. Su LE MAN P RER AK AC CN P Zl ,' @ W@ l0 l6 l6 l0 l lel Y I g l42Y lg lN lg lZ [Z lZ lZ lg 33 C@4 @ .

-l31 36 37 40 43 44 47 CAUSE CESCRIPTION AND CORRECTIVE ACTIONS h IilollAfter the first failure, the detector was replaced and ST 5091.01 " Source Range Func- l l,,,,  ; tional Test" was perforcad. After the second failure and return to normal, ST 5091.01; l

g lwas again perfor=ed. Both perfarnances of ST 5091.01 removed the unit from the Further troubleshooting is  ;

,,,3, {ActionStatementofTechnicalSpecification3.3.1.1.

,,,g ; oeing performed, but is complicated by the intermittent nature of the failure.

l r a s

'S1 k  % power oTHER STATUS 15 I Y' olscoVERY oESCRIPTIoN l

Ii' l5 l dh l 0 'l 0 l e l@l NA l l A l@l Operator Observation ACMVfTy CO TENT c.ELEAsto oFaELEasE Locke7eNoFRELEASE@

I t i 3 l [Z } h [,,Z j@l NA AuousToF ActiviTv "

[ NA hl '

l ,

I PERSONNEL ExposuAEs l

NuusER TYPE oEsemPrioN @ l j l L.u.,d 16 10 10 l@l Zl@l NA PER3oNNELINJu IES NuM oESCRIPTioN i

ii n i to9 io'5ERio I@t 11 12 NA ao 7

eSS op on cAMAGE To FACILITY Q fYPE oESCRIPTioN  %,,,/

- I l @l NA

• assut EscRi P rioN@ 8 0 0 2 0 <W 33 ""

• NRC uSE CnLv ,

l l!lIlllllI!!l}

1: lot IN hl 10NA _68 69 30. I 7 8 9 DVR 171-1 & M1.d.0F PREPARER PHONE:

l

.?

~

TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION N _ SUPPLEMENTAL INFORMATION FOR LER NP-33-77-100 t

DATE OF EVENT: December 1, 1977 and December 5, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Source Range Detector, NI-l's indication dropped to zero.

i -

j Conditions Prior to Occurrence: On December 1, 1977 at 1455 hours0.0168 days <br />0.404 hours <br />0.00241 weeks <br />5.536275e-4 months <br />, Source Range Neutron Detector NI-l's indication dropped to zero. The Control Rod Drive Trip Breakers were in the closed position, and the rods were capable of withdrawal.

This occurrence placed the unit in Action Statement 5 of Technical Specification 3.3.1.1, which requires two Source Range Detectors in Mode 3 with the Control Rod Drive System capable of rod withdrawal. An identical occurrence took place on December 5, 1977 at 0115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br />. Both occurrences were discovered by Operations personnel observing the drop in NI-l indication.

Designation of Apparent Cause of Occurrence: To date, each time NI-l's indication was lost, no apparent cause could be determined prior to the indication returning.

Just prior to NI-l failing on December 1, 1977, the Instrument and Control person-el had just finished replacing the preamplifier. It was then decided to replace

.he Source Range Neutron Detector. This was completed on December 3, 1977, and then on December 5, it failed again.

Analysis of Occurrence: There was no danger to the health and safety of the public or to unit personnel. The redundant Source Range Detector NI-2 was in service and operational throughout the occurrences. The thermal power level was maintained at less than 10-10 amps on the intermediate flux range instrumentation.

Corrective Action: ,After the failure on December 1, the detector was replaced.

Upon completion, ST 5091.01, the Source Range Functional Test, was performed and completed on December 3, 1977 at 0713 hours0.00825 days <br />0.198 hours <br />0.00118 weeks <br />2.712965e-4 months <br />. After the failure on December 5 and the subsecuent return of the indication to normal, ST 5091.01 was again performed at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on December 5. Both performances of the surveillance test removed the unit from the Action Statement of Technical Specification 3.3.1.1.

Failure Dats: This occurrence is a repetitive one,.however, the exact cause of this event is, as of yet, unknown.

4

'i J .

.- l

. TOLEDO EDISON COMPANY

.' DAVIS-BESSE UNIT ONE NUCLEAR POL'ER STATION Rev. 1 SUPPLEMENTAL INFORMATIGN FOR LER NP-33-77-100 1/5/78, C 4 DATES OF EVENT: December 1, 1977 and December 5, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Source Range Detector, NI-l's indication dropped to Zero.

Conditions Prior to Occurrence: The unit was in Mode 3, with Power (MWT) = 0, and Load (MWE) = 0.

i 1

Description of Occurrence: On December 1, 1977, at 1455 hours0.0168 days <br />0.404 hours <br />0.00241 weeks <br />5.536275e-4 months <br />, Source Range Neutron Detector NI-l's indication dropped to zero. The Control Rod Drive Trip Breakers were in the closed position, and the rods were capable of withdrawal.

This occurrence placed the unit in Action Statement 5 of Technical Specification 3.3.1.1, which requires two Source Range Detectors in Mode 3 with the Control Rod Drive System capable of rod withdrawal. An identical occurrence took place on December 5, 1977 at 0115 hours0.00133 days <br />0.0319 hours <br />1.901455e-4 weeks <br />4.37575e-5 months <br />. Both occurrences were discovered by Operations i personnel observing the drop in NI-l indication.

i Designation of Aeoarent Cause of Occurrence: To date, each time NI-l's indication was lost, no apparent cause could be determined prior to the indication returning.

Just prior to NI-l failing on December 1, 1977, the Instrument and Control person-nel had just finished replacing the preamplifier. It was then decided to replace the Source Range Neutron Detector. This was completed on December 3, 1977, and then on December 5, it failed again.

Analysis of Occurrence: There was no danger to the health and safety of the public or to unit personnel. The redundant Source Range Detector NI-2 was in service and operational throughout the occurrences. The thermal power level was maintained at less than 10-10 amps on the int ~ermediate flux range instrumentation.

Corrective Action: After the failure on December 1, the detector was replaced.

Upon completion, ST 5091.01, the Source Range Functional Test, was performed and completed on December 3, 1977 at 0713 hours0.00825 days <br />0.198 hours <br />0.00118 weeks <br />2.712965e-4 months <br />. After the failure on December 5 and the subsequent return of the indication to normal, ST 5091.01 was again performed at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on December 5. Both performances of the surveillance test removed the unit from the Action Statement of Technical Specification 3.3.1.1.

Failure Data: This occurrence is a repetitive one, however, the exact cause of this event is, as of yet, unknown.

9

-e _ - .r . g -.. . _ . , _ . . , , . .