ML18037A328

LER 81-004/01T-0:on 810209,main Steam Radiation Monitor 111 Signal Fluctuated,Causing Multiple Half Scrams.Caused by Loose detector-to-cable Connector.Connector Tightened

ML18037A328
Person / Time
Site:	Nine Mile Point
Issue date:	02/23/1981
From:	Harrison P NIAGARA MOHAWK POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML17053C373	List: ML17053C372 ML18037A328
References
LER-81-004-01T, LER-81-4-1T, NUDOCS 8103030757
Download: ML18037A328 (4)

Text

]; NRO F OR M 366 I7.771 S. NUCLEAR REGULATORY C I ON LICENSEE EVENT REPORT r

CONTROL BLOCK: pl (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

I 6

[oD1]

7 8 9 N Y N LICENSEE CODE M P 1 14 Q3 15 0 0 0 0 0 LICENSE NUMBER 0 0 0 0 25 Q3 26 4 1 1 LICENSE TYPE 1 1 30 Q4~ps 57 CAT 58 CON'T 60 61 DOCKET NUMBER 68 Q 69 FVENT DATE 74 Qs 75 REPORT DATE 80 OB EVENT DESCRIPTION AND PROBABLE CONSEQUENCES 10

~o 2 Durin normal o eration the 8111 Main Steam Radiation Monitor in ut to the RPS

~D 3 Trip System was inoperable for approximately 90 minutes while the 811 Trip System was

~D 4 left in the untripped condition. This is.contrar to the RPS Instrument Channel o er-

~O 5 ability requirements as given in the Technical Specifications. The Technical Specifi-

~D B cations re uire that the Tri S stem be laced in the tri ed condition when either of

~O 7 the Instrument Channels associated with that Trip S stem is ino erable. During this 4

time the redundant monitor input to /Ill Trip System, and the two (2) (SEE OVER) 7 8 9 80 SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENTCODE SUBCODE SUBCODE

~SH Q33 ~A Q33 ~A Q33 R E 1 A Y X Q14 ~X Qls ~Z Q13 7 8 9 10 11 12 13 18 '19 20 SEQUENTIAL OCCURRENCE REPORT REVISION Q33 .

LER/RO Rssosv ACTION . FUTURE EVENT YEAR

~81 ZI 22 EFFECT

+

23 SHUTDOWN

~00 24 REPORT NO.

4 26

+A 27

~01 28 ATTACHMENT CODE Z9 NPRDMI TYPE

~T 30-PRIME COMP.

+3I

+0 32 NO.

COMPONENT TAKEN ACTION ON PLANT METHOD HOURS +2~ SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

~XQls ~H ~ZQ33 0 0 0 0 0 0 8 0 33 34 Q33 apso 35 36 37 40

~Y 41 Q33 ~NQ34 42

~N 43 Q33 44 47 Qss CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 o The subdect radiation monitor signal had been &luctuating sufficiently to cause multi-pie spurious half scram actuations. Consequently, the SSS granted permission to in-stall a block in .the RPS actuation relay of the sublect monitor, to prevent further 3 spurious half scrams, while the Instrument technician was to proceed with trouble 4 shooting by withdrawing the detector from the holder. Upon removal (SEE OVER).

7 8 9 80 s

FACILITY STATUS E Qss ~08

% POWER 7 pss OTHER STATUS N/A

~

~3P METHOD OF DISCOVERY

~SQ33 DISCOVERY DESCRIPTION 032 SUPERVISION REVIEW 7 8 9 10 12 13 44 45 80 ACTIVITY CONTENT RELEASED OF RELEASE AMOUNTOF ACTIVITY ~ LOCATION OF RELEASE 7

3 8

~Z 9

Q33 ~ZQ34 10 PERSONNEL EXPOSURES 11 N/A 44'5 N/A 80 7 8 9 'I l 12 13 80 PERSONNEL INJURIES 7 8 9 11 12 80 LOSS OF OR DAMAGE TO FACILITY 43 7 8 9 10 80 DGZ LEIS ISSUED P U 8 L I C IT Y DESCRIPTION ~ NRC USE ONLY 44 a

3 8 9 68 69 10~@g 80 a 0

~AMS OF PRSPARSR PHONE: L

EVENT DESCRIPTION AND PROBABLE CONSEQUENCES monitor inputs to //12 Trip System were operable, thus there was no signi-ficant safety concern.

CAUSE DESCRIPTION AND CORRECTION ACTIONS of the detector, it was discovered that the detector-to-cable connector was loose, which was causing the fluctuating output signal. The connector was tightened, the detector reinstalled, and the monitor returned to normal indication. The, RPS relay block was then removed. At this time the Pill Main Steam Line Radiation Monitor was fully operable.

In order to prevent occurrences of this nature in the future, several corrective actions have been taken. First, a review of the circumstances was made with the shift personnel involved. Second, an instruction has been issued to all operations personnel regarding this matter. Third, procedures changes have been made to ensure specific Technical Specifi-cation reviews are made and documented when equipment important to safety is removed from service. Fourth, this incident and aforementioned pro-cedure changes will be incorporated into regularly scheduled training sessions for Operations personnel. Fifth, training sessions will be conducted within the Instrument and Control Department, regarding instrumentation important to safety and the Technical Specifications rquirements in general.

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