05000336/LER-1995-020-01, :on 950516,automatic Actuation of Engineered Safety Feature Occurred During Maint.Caused by Procedure Deficiency.Revised Operations Procedure OP-2384 to Add Appropriate Caution for de-energization of Cabinets

:on 950516,automatic Actuation of Engineered Safety Feature Occurred During Maint.Caused by Procedure Deficiency.Revised Operations Procedure OP-2384 to Add Appropriate Caution for de-energization of Cabinets

ML20138Q649
Person / Time
Site:	Millstone
Issue date:	03/03/1997
From:	Joshi R NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20138Q648	List: 05000336/LER-1995-020-01, :on 950516,automatic Actuation of Engineered Safety Feature Occurred During Maint.Caused by Procedure Deficiency.Revised Operations Procedure OP-2384 to Add Appropriate Caution for de-energization of Cabinets
References
LER-95-020-01, LER-95-20-1, NUDOCS 9703070134
Download: ML20138Q649 (4)

LER-1995-020, on 950516,automatic Actuation of Engineered Safety Feature Occurred During Maint.Caused by Procedure Deficiency.Revised Operations Procedure OP-2384 to Add Appropriate Caution for de-energization of Cabinets

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(iv)(B), System Actuation
3361995020R01 - NRC Website

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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OM8 NO. 3150-o1o4 l

EXPIRES o4/30/98 e

i LICENSEE EVENT REPORT (LER)

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DOCKET NUMBER (2)

PAGE (3)

Millstone Nuclear Power Station Unit 2 05000336 1OF3 t

L TITLE (4) l Automatic Actuation of an Engineered Safety Feature During Maintenance I

EVENT DATE 15)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILITIES INVOLVED (8)

SEQ R

N MONTH DAY YEAR YEAR MONTH DAY YEAR U

NU R

05 16 95 95

-- 020 -

01 03 03 97 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 1o CFR 5: (Check one or more) (11) 6 MODE (9) 20.2201(b) 20.2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(aH3)(i) 50.73(a)(2)(ii) 50.73(a)(2Hx)

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LEVEL (10) 20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50.73(a)(2)(iii) 7J.71 20.2203(a)(2)(ii) 20.2203(a)(4)

X 50.73(a)(2)(iv)

OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v)

Specify in Abstract below 20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (include Area Codel R. G. Joshi, MP2 Nuclear Licensing (860)440-2080

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COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

^

CAUSE

SYSTEM COMPONENT MANUFACTURER

CAUSE

SYSTEM COMPONENT MANUFACTURER o PR0 g

SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR YES SUBMISSION i

X NO DATE (15)

(if yes, complete EXPECTED SUBMISSION DATE).

ABSTRACT (Limit to 1400 spaces,i.e. approximately15 single-spacedtypewrittenlines) (16) i On May 16,1995 at 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br />, with the plant in Mode 6, an automatic actuation of an Engineered Safety l

Feature (ESF) occurred. Engineered Safety Feature Actuation System (ESAS) Cabinet 5 was being powered i

down for maintenance. When fuses were removed in accordance with the applicable procedure an inadvertent

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actuation occurred, Facility 1 Enclosure Building Filtration System f an (F25A) and Control Room Air Conditioning f an (F32A) started and Containment Radiation Monitor f an (F39A) shut down. Only the potential for inadvertent actuations during power restoration was anticipated in the procedure.

The causes of the event were a procedure deficiency and the lack of design features for downpowering the actuation cabinets for maintenance purposes. Fuses in the cabinet cannot be removed and reinstalled reliably without the potential for inadvertent actuations.

As a result of this event, operations procedure OP-2384 was revised to add the appropriate caution for de-energization of the cabinets. Additionally, a design change to simplify maintenance activities will be implemented during the next refueling outage, RFO13.

9703070134 970303 PDR ADOCK 05000336 S

PDR

'U.S NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION Millstone Nuclear Power Station Unit 2 05000336 NUMBER NUMBER 2 of 3 95 020 01 TEXT (If more space is required, use additionalcopies of NRC Form 366A) (17) l.

Description of Event

On May 16,1995 at 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br />, with the plant in Mode 6, operators were preparing to remove Engineered Safety Features Actuation System (ESAS) Facility 1 actuation cabinet 5 from service to implement modifications to the system. Operators were in the process of powering down actuation cabinet 5 per operations procedure OP2384. Upon removal of one of the cabinet's + 24 Vdc power supply fuses (Block Relay Power Supply), Facility 1 Enclosure Building Filtration System (EBFS) fan F25A and Control Room Air Conditioning (CRAC) fan F32A started, and Containment Radiation Monitor fan F39A shut down automatically. Fans F25A and F32A were immediately shutdown.

11.

Cause of Event

The causes of the event were a procedure deficiency and the lack of design features for downpowering the actuation cabinets for maintenance purposes. It is not always possible to remove the fuses without getting a momentary contact causing an actuation cabinet re energization sequence.

A caution in the procedure did note the potential for automatic actuation of ESAS equipment, but only during restoration of the power supply fuses, not during their removal. It is believed that as the operator removed the power supply fuse, it momentarily recontacted the fuse holder, generating the component actuation (which is expected when the fuse is reinstalled).

The block logic that would have prevented these actuations is powered from the same source that supplies the aduation modules. Thus, when power is interrupted or restored, a limited number of inadvertent actuations may occur due to the f act that all blocks do not receive power at the same time, which is required to prevent an actuation signal.

Ill. Analysis of Event This event is being reported pursuant to requirements of 10 CFR 50.73(a)(2)(iv)(B) as any event or condition that resulted in the manual or automatic actuation of any Engineered Safety Feature (ESF).

An investigation has determined that there were no safety consequences associated with the event. At the time of the event, the ESAS Facility 1 actuation cabinet 5 was being shutdown for modifications and was not being relied on to be operable. The redundant Facility 2 equipment was available and operable to mitigate the consequences of any postulated accident for Mode 6. The cause of the inadvertent actuation was associated with the maintenance activities.

IV. Corrective Action

As a result of this event, Design Engineering performed an investigation. It was concluded that the lack of design features for downpowering the actuation cabinets for maintenance purposes identified by this event only affects the system during maintenance, it does not affect the in service performance of the system safety function. Operations procedure OP-2384 was revised to add the appropriate caution statement for de-energization of the cabinets.

NRC F RM 366A

. U.S. NUCLEAR REGULATORY COMMISSION R95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION Millstone Nuclear Power Station Unit 2 05000336 NUMBER NUMBER 3 of 3 95 020 01 TEXT (If more space os required use additionalcopies of NRC Form 366Al (17)

Additionally, a design change to simplify maintenance activities will be implemented during the next refueling outage, RFO13.

V.

Additional Information

Similar LER's:

LER 94-010-01, inadvertent Actuation of ESAS Equipment.

LER 94 017-01, inadvertent ESAS Actuations.

LER 95-005-01, inadvertent Actuation of ESF Equipment.

Ells Codes:

JE; XC; E059 -

Engineered Safety Actuation System VC; FAN Enclosure Building Filter Fan Vl; FAN Control Room Air Conditioning Fan IL; FAN Containment Radiation Monitor Fan ACTION ITEM TRACKING AND TRENDING INFORMATION

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