ML20042F281

LER 90-007-00:on 900403,inadvertent,inconsequential Safety Features Actuation Signal Occured While Defueled.Caused by Incidental Contact W/Monitor in Containment.Temporary Barriers Built Around monitors.W/900503 Ltr

ML20042F281
Person / Time
Site:	Davis Besse
Issue date:	05/03/1990
From:	Storz L, Stotz J TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-007, LER-90-7, NP33-90-008, NP33-90-8, NUDOCS 9005080095
Download: ML20042F281 (5)

Text

• . .

EISON CDISDN PLAZA 330 MADISDN AVENUE TOLEDO, DHlo 43052 0001 May 3, 1990 Log No. BB90 00703 NP33-90-008 Docket No. 50-346 License No NPT-3 United States Nuclear Regulatory Commission -;

Document Control Desk Washington, D. C. 20555 i Gentlemen LER 90-007 Davis-Besse Nuclear Power Station, Unit 110. 1 Date of Occurrence - April 3, 1990 -

Enclosed please find Licensee Event Report 90-007 vhich is being written to provide 30 days notification of the subject occurrence. This report is.being submitted in accordance with 10CFR50.73(a)(2)(iv). ,

9 Yours truly,

/ $uk A Louis F. Storz +

Plant Manager Davis-Besse Nuclear Power Station LFS/p1f Enclosure cc: Mr. A. Bert Davis Regional Administrator USNRC Region III Mr. Paul Byron  ;

DB-1 NRC Sr. Resident Inspector

• l d

9005090095 900503 PDR ADOCK 05000346 g PDC

~

$$SA N' ' I

.ne . me u2 wuC6saa mov6aton, come.m.o=

m' .

a mioveoousno.sim eine LICENSEE EVENT REPORT (LER) \

oockt? wueeMk (t) FAM 4 f aca617Y Naast n)

Davis-Ecsse Unit No. 1 0 l 5 l 0 l 0 l o 13 14 I r, 1 l0Fl 014 t

tit 6s is Inadvertent Inconsequential STAS Actuation While befueled ave =t oatt m ten wouna = l nera cart m otwen eaonmee swvoLveo si uoNta nav vtan nin Jug;;','6 == MoNtu car vtan e nomtv **.= coCatt Nownam o 151010101 l 1 0l4 0l3 9 0 9l0 0 l 0l 7 0l0 0l 5 0l3 9l 0 oisioio,o, l l tHe nePon le evemenso evnevawr to v $ nouinewswte o, is Can o ro . ., s. w i nu "8" E D Se .SeM 8 .Gelet esseislanM tas1M sesswmm tasim g 0 se assianum _

es.m w m sesswer.m y <,,ggg nei 0l0 i so.eesianum esmwm _ _

ot sesswmm sesswminnan mens

$$ . ,r asisownne _ _

J., $k sunwnne mssansim mismienmum QFh!?

s ' e-

m. sewnn,i m.nwman m.nwan.i LICeNett oowtact PoA fHis LtR nel

,,wt teose oat NUMeen area Cool Jan C. Stotz. Engineer - Maintenance Planning 4l1 l 9 3l21l-1 1 7l5 l 4l 4 CoMPLitt oNt LIN PoR laCH CoMpoNtett taltunt osecattso IN THis DepoAt H )

Cav58 848ttM CoMPohtNv "$Ng$O To 8 h caust sytttM CoM>oNeNv "(Ngk0 AffE !If: j

. 'U ^ -:y% P l I I I I I I -

l i i i i i 1 'E N:o 'sNf "

D'

$9 $$

n' N

%:> W '

l l l l l l l l l l l l l l suPPLEM0Wral RepoAt $3tP0Cieo ne MoNvM oav vt# R D vu tor r . e,. emeno svowwow carts

] No ) l l aan.act ru-= . .oo u... . ., m . - -,, no l

On April 3, 1990, at 2306 hor s vith the reactor defueled, the station l experienced an inadvertent Safety Features Actuation System (STAS) Level 1 l actuation when containment radiation monitor RE2005 spiked after being bumped by a vorker in containment. On April 7, 1990, at 1031 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.922955e-4 months <br />, another Ievel 1 actuation occurred when the same detector spiked. This time the cause could not be determined. Later at 1719 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.540795e-4 months <br />, the station experienced an SFAS Level 1 through 4 actuation when attempting to pull the containment pressure transmitter input fuses to SPAS Channel 1. Pulling input fuses to SFAS, where possible, was corrective action after the 1031 hour0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.922955e-4 months <br /> actuation. In each

( actuation, another channel of SFAS had previously been de-energized for

! maintenance and cleaning which caused the inadvertent trip of a single channel ,

to become an SFAS actuation. A major contributing f actor is the design of  !

SFAS vhich does not allov *.he whole channel to be bypassed or de-energized, i

Barriers were placed around all four containment radiation detectors by April 6, 1990, to help prevent inadvertent contact. RE2005 is being monitored to determine the cause of any future spikes. An evaluation vill be performed to determine the best method to reduce inadvertent actuations when SFAS is not required, i

GJtuan D

anc w maa v i waian ...u6avoav commission UCENSEE l VENT REPORT (LER) TEXT CONTINUATION e*aovie ow wo **-o*

impineswa

,aC6uty esassi sie ooc #4% Nd'8Hk 488 Ltt Wueth iti 'Aol (3' yaaa H gg,* 6 7(* T,"

Davis-Besse Unit No. 1 0 l6 l0 l 0 l 0 l 3l 416 9l0 --

010l7 --

Olo 0l 2 0F 0l4 varee . .asm ac wasawim Description of Occurrence:

On April 3, 1990, at 2306 hours0.0267 days <br />0.641 hours <br />0.00381 weeks <br />8.77433e-4 months <br />, with the reactor defueled, the station experienced an inadvertent Safety Features Actuation System (SFAS-JE) Level 1 lll actuation when containment radiation monitor RE2005 spiked. This tripped that function in SFAS Char:; ' 2. Frior to the actuation SFAS Channel I had been de-energized for maintenance and cleaning. The Level 1 actuation caused containment isolation, per design. SFAS Channel 2 was reset by 2310 hours0.0267 days <br />0.642 hours <br />0.00382 weeks <br />8.78955e-4 months <br />.

This event was reported to the NRC at 0003 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> on April 4, 1990, via the ENS per 10CFR50.72(b)(2)(ii) as the automatic actuation of Engineered Safety Features (ESF) equipment.

On April 7, 1990, at 1031 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.922955e-4 months <br />, with the reactor defueled, the station experienced another inadvertent SFAS Level 1 actuation when RE2005 spiked and tripped SFAS Channel 2. Frior to the actuation, SFAS Channel 4 had been de-energized for maintenance and cleaning. The Level 1 actuction caused containment isolation. The NRC vas notified at 1340 hours0.0155 days <br />0.372 hours <br />0.00222 weeks <br />5.0987e-4 months <br /> via the ENS per 10CFR50.72(b)(2)(li).

On April 7, 1990, at 1719 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.540795e-4 months <br />, with the reactor defueled, the station experienced an inadvertent Level 1 through 4 actuation when pulling containment pressure transmitter input fuses to SFAS Channel 1. Difficulties pulling the fuse caused a spike and a trip of this parameter in Channel 1.

Prior to the actuation, SFAS Channel 4 had been de-energized for maintenance and cleaning. Pulling of this and other input fuses was part of the corrective action from the 1031 hour0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.922955e-4 months <br /> actuation and was intended to reduce at least some of the sources for inadvertent actuations. The NRC vas notified at 1945 hours0.0225 days <br />0.54 hours <br />0.00322 weeks <br />7.400725e-4 months <br />.

These events are being reported as an LER under 10CFR50.73(a)(2)(iv) as the hutomatic actuation of ESF equipment.

Apparent Cause of Occurrence:

The cause of the RE2005 netuation on April 3,'1990, at 2306 hours0.0267 days <br />0.641 hours <br />0.00381 weeks <br />8.77433e-4 months <br /> was incidental contact with the monitor in containment. This monitor is mounted to the Shield Building in the annulus during normal power operation. During refueling operations, the containment radiation monitors are relocated inside the containment vessel. Vith SFAS Channel 1 de-energized, the necessary logic vas complete for a high containment radiation SFAS Level 1 actuation.

The'cause of the RE2005 spike on April 7, 1990,'at 1031' hours is not kne"n.

Since the previous bumping on April 3, 1990, protective barriers were installed around the detectors to help prevent contact. Accidental contact is not thought to be the cause for this actuation. Radiological Controls could not find any movement of radioactive material near the detector that might have set it off.

. , v . o.o ,...+.n d. 6

,~, g ,. . . ~ .

wee man u muc66.. ...utatem, commm o=

. UCENSEE EVENT REPORT (LEM TEXT CONTINUATION waovio one ao mo-o*

snesmo pas,Lif t AM tti D0ctit ,#unSth 485 kga Nunega ign P668 tt

....

• um.* gg Davis-Besse Unit No. 1 0 l6 l 0 l 0 l 0 l 3 l4 lr, 9l0 -

0l0 l 7 -

0l0 nlt OF n l 11 von e . manew anc a = mew em The cause of the Level 1 through 4 actuation was a high containment pressure signal that occurred when the containment pressure transmitter power fuse was being pulled. The attempt to de-energize some of these signals was part of the corrective action from the 1031 hour0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.922955e-4 months <br /> event.

The major contributing factor in all of these events is the design of SFAS.

It does not allow the. system to be shutdown without falling'the output devices to their safety positions / status. The only way to avoid the actuation is to de-energize the output equipment. This is not always practical because for normal operation and for maintenance and cleaning, equipment may be needed in its normal status. Therefore, when a channel is de-energized, it takes only one more inadvertent actuation in another channel of any one of the parameters monitored by SPAS to initiate an ESF actuation.

Analysis of Occurrences SFAS is not required by Technical Specifications when the reactor is defueled.

The inadvertent actuations did not create any significant safety concerns. It was a disruption to the outage activities.

Corrective Action:

After the bumping of RE2005 at 2306 hours0.0267 days <br />0.641 hours <br />0.00381 weeks <br />8.77433e-4 months <br /> on April 3, 1990, temporary barriers were built around the SFAS radiation monitors. They were in place by April 6, 1990. RE2005 is being monitored by special recorders in an attempt to pinpoint the cause of any future actuations.

After RE2005 actuated at 1031 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.922955e-4 months <br /> on April 7, 1990, a cause could not be determined. it was decided to de-energize the input signals to the SFAS cabinets, where possible, to eliminate at least some of the potential sources of inadvertent actuations. It was while this effort m in progress that the high containment' pressure actuation occurred.

An evaluation vill be performed to determine if it would be cost effective to modify the SFAS design or whether other administrative amd procedural strategies can be used to minimize inadvertent actuations when SFAS is not required to be operable.

Failure Datat The previous inadvertent SFAS actuation was reported in LER 90-006.' That event was caused by accidental contact with a breaker switch (while defueled) which caused loss'of power to two SFAS panels. LER 89-017 involved a failed' relay in one channel that was not detected while testing in a second channel  ;

which' caused a component actuation. The next previous event was reported in i

74*oa= =** .u s omose ov4eersii

l l

• I i

v. cL.an m.cotatomy couni,esion l anc y anna  ;

P. . . UCENSEE EVENT REPORT (LERI TEXT CONTINUATION **aovie ow =o **-**

.......u.  ;

. 6 1, .., .oc. . . ., ,,,,,,,,,,,,,, ,.e. ..,  ;

..a " b!,;' " TJit Davis-Besse Unit No. 1 ol6l0lolol3l4l6 9 l0 - 0 l Oj 7 -- 001 ol 4 or o l4 l terr n . sm me w sm v on .

1 LER 88-012 when two containment radiation monitors were tripped when  !

radioactive material was moved past the detectors. LER 90-006 is related to the cause of at least one of the actuations in this current report.

REPORT NO.t NP33-90-000 PCAOR NO. 90-0279, 90-0297, 90-0298  !

1 i

5 i

f f

a j

?

?

r d

y~ "" _ _ _ _ .

. . o,0 , . .... . . . . . .;

. . _