Information Notice 1993-35, Insights from Common-Cause Failure Events

Insights from Common-Cause Failure Events
	ML031070487
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	05/12/1993
From:	Grimes B; Office of Nuclear Reactor Regulation
To:	;
References
	IN-93-035, NUDOCS 9305060160
	Download: ML031070487 (9)
	v • d • e

II

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 May 12, 1993 NRC INFORMATION NOTICE 93-35: INSIGHTS FROM COMMON-CAUSE FAILURE EVENTS

Addressees

All holders of operating licenses or construction permits for nuclear power

plants (NPPs).

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information

notice to inform addressees about the publication of an NRC report on common- mode and common-cause failure events that could occur at nuclear power plants.

It is expected that recipients will review the information for applicability

to their facilities and consider actions, as appropriate, to avoid similar

problems. However, suggestions contained In this information notice are not

NRC requirements; therefore, no specific action or written response is

required.

Discussion

The Office for Analysis and Evaluation of Operational Data (AEOD) published a

report, 'Insights from Common-Mode Failure Events," AEOD/E92-02, in June 1992 and issued Supplement 1 in February 1993.* The staff reviewed 62 selected

licensee event reports that discussed actual or potential common-cause

failures. Of the 62 events reviewed, 16 also were identified as precursors in

the accident sequence precursor program (ASP). Common-cause failures may

significantly degrade safety since they can defeat the additional benefit has

normally provided by redundant systems. Furthermore, common-cause failure nuclear

been cited as a major uncertainty in probabilistic risk assessments of

power plants.

Most of the reports used in the AEOD study were prompted by events that the

occurred in 1990. In the study, the staff used reports of events where

failed equipment was considered neither 'recoverable' nor .self-revealing.' A

failure that is recoverable is one in which the plant condition could be in

restored by taking a corrective action during the event. However, failure a

a location inaccessible during an accident, such as inside the containment;

failure of equipment needed for a rapidly developing event such as a loss-of- coolant accident; a challenge to pressure vessel integrity; or a backwards

installation of a necessary valve are considered failures that are not

recoverable. For a self-revealing condition, the licensee would presumably

Coples of this report and its supplement are available for inspection

and copying in the NRC Public Document Room, 2120 L Street N.W., O

Washington, D.C. 20037 a 'EM

9305060160 DrnMA -. _ &- _ he P A

J.y - 0 j,5 -7J UO Ilcps

IN 93-35 '

May 12, 1993 correct the situation before the event occurred that required

The staff excluded such conditions from this study. the equipment.

The AEOD report attempted to identify the actions that would

be most effective

in precluding or reducing the likelihood of common-cause failures

nuclear power plants. Each of the events was reviewed against at operating

potential actions: comprehensive testing, staggered testing, a set of eight

post-maintenance

testing, using equipment from different manufacturers in redundant

(diverse equipment), using equipment with larger design margin, trains

frequency of testing, providing adequate separation increasing

different maintenance personnel'on separate trains. ofNo trains, single

and using

have alleviated all the common-cause failures in the study. action would

the events, the action that had the highest potential benefit Considering all

equipment with larger design margins. This action alone would was using

about 56 percent of the situations examined in the AEOD study. have corrected

comprehensive systems tests, ensuring adequate train separation, Performing

diverse equipment each had a potential benefit in about 27 and using

cases. The use of staggered surveillance testing would have percent of the

20 percent of the events. benefited

The staff noted that about two-thirds of the events were

fabrication, and installation errors that may be undetectedrelated to design, of time. The remaining events were associated with maintenancefor long periods

either preventive or corrective. The major alleviating action deficiencies, identified for

these maintenance-related events was staggered survelillance-testing, assumed to result in a shorter time during which the common-mode iwhich- is- undetected. failure is

This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please call one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contact: S. Israel, AEOD

(301) 492-4437 Attachment:

List of Recently Issued NRC Information Notices

-4

Attachment

IN 93-35 May 12, 1993 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

93-34, Potential for Loss of 04/06/93 All holders of OLs or CPs

Supp. 1 Emergency Cooling for nuclear power reactors.

Function Due to A

Combination of

Operational and Post- Loca Debris in Contain- ment

93-34 Potential for Loss of 04/26/93 All holders of OLs or CPs

Emergency Cooling for nuclear power reactors.

Function Due to A

Combination of

Operational and Post- Loca Debris in Contain- ment

93-33 Potential Deficiency 04/28/93 All holders of OLs or CPs

of Certain Class IE for nuclear power reactors.

Instrumentation and

Control Cables

93-32 Nonconservative Inputs 04/21/93 All holders of OLs or CPs

for Boron Dilution for pressurized water

Event Analysis reactors (PWRs).

X Training of Nurses 04/13/93 All U.S. Nuclear Regulatory

Responsible for the Commission medical

Care of Patients with licensees.

Brachytherapy Implants

93-30 NRC Requirements for 04/12/93 All U.S. Nuclear Regulatory

Evaluation of Wipe Commission medical

Test Results; Cali- licensees.

bration of Count Rate

Survey Instruments

93-29 Problems with the Use 04/12/93 All holders of OLs or CPs

of Unshielded Test Leads for nuclear power reactors.

in Reactor Protection

System Circuitry

OL -'Operating License

CP = Construction Permit

V IN 93-35 tj

May 12, 1993 correct the situation before the event occurred that required the equipment.

The staff excluded such conditions from this study.

The AEOD report attempted to identify the actions that would be most effective

in precluding or reducing the likelihood of common-cause failures at operating

nuclear power plants. Each of the events was reviewed against a set of eight

potential actions: comprehensive testing, staggered testing, post-maintenance

testing, using equipment from different manufacturers in redundant trains

(diverse equipment), using equipment with larger design margin, increasing

frequency of testing, providing adequate separation of trains, and using

different maintenance personnel on separate trains. No single action would

have alleviated all the common-cause failures in the study. Considering all

the events, the action that had the highest potential benefit was using

equipment with larger design margins. This action alone would have corrected

about 56 percent of the situations examined in the AEOD study. Performing

comprehensive systems tests, ensuring adequate train separation,/ and using

diverse equipment each had a potential benefit in about 27 percent of the

cases. The use of staggered surveillance testing would have benefited

20 percent of the events.

The staff noted that about two-thirds of the events were related to design, fabrication, and installation errors that may be undetected for long periods

of time. The remaining events were associated with maintenance deficiencies, either preventive or corrective. The major alleviating action identified for

these maintenance-related events was staggered surveillance testing, which is

assumed to result in a shorter time during which the common-mode failure is

undetected.

This information notice requires no specific action or written response. If

you have any questions about the information inthis notice, please call one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Original sIgned Uy

Brian K.Grimeg

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contact: S. Israel, AEOD

(301) 492-4437 Attachment:

List of Recently Issued NRC Information Notices

SEE PREVIOUS CONCURRENCE

OGCB:DORS:NRR *TECH ED *ROAB:AEOD *C:ROAB:AEOD *D:DSSA:NRR

CVHodge RSanders SIsrael JERosenthal ACThadani

03/ /93 03/11/93 03/11/93 03/19/93 03/24/93

C:OGCB:DORS:NRR

GHMarcus ( Sii~

03/31/93 05/X /93 DOCUMENT NAME: 93-35.IN

IN 93- May , 1993 presumably correct the situation before the event occurred that required the

equipment. The staff excluded such events from this study.