05000220/LER-1981-004-01, /01T-0:on 810209,main Steam Radiation Monitor 111 Signal Fluctuated,Causing Multiple Half Scrams.Caused by Loose detector-to-cable Connector.Connector Tightened

/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: 05000220/LER-1981-004, Forwards LER 81-004/01T-0 05000220/LER-1981-004-01, /01T-0:on 810209,main Steam Radiation Monitor 111 Signal Fluctuated,Causing Multiple Half Scrams.Caused by Loose detector-to-cable Connector.Connector Tightened ML17053C372 ML18037A328
References
LER-81-004-01T, LER-81-4-1T, NUDOCS 8103030757
Download: ML18037A328 (4)

LER-1981-004, /01T-0:on 810209,main Steam Radiation Monitor 111 Signal Fluctuated,Causing Multiple Half Scrams.Caused by Loose detector-to-cable Connector.Connector Tightened

Event date:
Report date:
2201981004R01 - NRC Website

text

S. NUCLEAR REGULATORY C I

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];NRO F ORM 366 I7.771 LICENSEE EVENT REPORT r

CONTROL BLOCK:

pl (PLEASE PRINT OR TYPE ALLREQUIRED INFORMATION)

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LICENSEE CODE 14 15 LICENSE NUMBER 25 26 LICENSE TYPE 30 57 CAT 58 CON'T Q

OB 60 61 DOCKET NUMBER 68 69 FVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES 10

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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-

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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

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~A Q33

~A Q33 R

E 1

A Y

X Q14

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8 9

10 11 12 13 18

'19 20 SEQUENTIAL OCCURRENCE REPORT REVISION LER/RO EVENTYEAR REPORT NO.

CODE TYPE NO.

Q33

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+0 ZI 22 23 24 26 27 28 Z9 30-3I 32 ACTION. FUTURE EFFECT SHUTDOWN ATTACHMENT NPRDMI PRIME COMP.

COMPONENT TAKEN ACTION ON PLANT METHOD HOURS +2~

SUBMITTED FORM SUB.

SUPPLIER MANUFACTURER

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0 0

0

~Y Q33

~NQ34

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0 Qss 33 34 35 36 37 40 41 42 43 44 47 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 Upon removal (SEE OVER).

80 DISCOVERY DESCRIPTION 032 SUPERVISION REVIEW 80 LOCATIONOF RELEASE N/A 80 80 80 80 NRC USE ONLY 44a 3

80 a 0L 68 69 PHONE:

4 shooting by withdrawing the detector from the holder.

7 8

9 FACILITY

~3P METHOD OF STATUS

% POWER OTHER STATUS ~

DISCOVERY s

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pss N/A

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10 12 13 44 45 ACTIVITY CONTENT RELEASED OF RELEASE AMOUNTOF ACTIVITY~

3

~Z Q33

~ZQ34 N/A 7

8 9

10 11 44'5 PERSONNEL EXPOSURES 7

8 9

'Il 12 13 PERSONNEL INJURIES 7

8 9

11 12 LOSS OF OR DAMAGETO FACILITY 43 7

8 9

10 P U8 L I C IT Y ISSUED DESCRIPTION ~

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9 10~@g

~AMS OF PRSPARSR

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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