Information Notice 1991-84, Problems with Criticality Alarm Components/Systems

Problems with Criticality Alarm Components/Systems

ML031190217
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, 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:	12/26/1991
From:	Cunningham R NRC/NMSS/IMNS
To:
References
IN-91-084, NUDOCS 9112190113
Download: ML031190217 (5)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555 December 26, 1991 NRC INFORMATION NOTICE 91-84: PROBLEMS WITH CRITICALITY ALARM

COMPONENTS/SYSTEMS

Addressees

spent

AllNuclear Regulatory Commission (NRC) fuel cycle licensees, interim

fuel storage licensees, and critical mass licensees.

Purpose

NRC is issuing this notice to remind licensees of the importance of adequate

maintenance, and response actions, reviews of plant modification, installation, purpose.

to ensure that required criticality alarm systems meet their intended

It is expected that recipients will review this information for applicability actions,- to their facilities, distribute it to responsible staff, and consider contained in

as appropriate, to avoid similar problems. However, suggestions

any new NRC requirements, and no

this information notice do not constitute

written response is required.

Description of Circumstances

The following cases are recent events involving problems with licensee's by, NRC.

criticality alarm systems that have been reported to, or discovered

licensee

Case 1: During a routine test of the criticality alarm system, adid not

discovered that several of the site's audible alarms ("howlers")

actuate. The licensee found that wiring to the alarms had been accidentally

broken while other electrical cables were being pulled throughsystem the cable run

The licensee's provided

that contained the criticality alarm wiring. alarms

indication, prior to the next scheduled test, that some of-the audible

had been disabled.

facility

Case 2: Engineering drawings describing modifications at a licensedreview of

specified removal of "heat detectors (radiation)." The licensee's

rather

the modification package did not recognize that it included removal, the specified

than relocation, of criticality alarm system detectors. When

panel.

detectors were removed no alarm was generated at the system monitoring such a

alarm panel was wired in

Subsequent investigation disclosed that the panel (an

way that, although a "failure" light was activated at an intermediate

of detector" signal was not generated

unmanned location), a "loss of power/loss

at the monitoring panel in a normally manned area.

9112190113 RI t I c)VI

002098

0,F -_

III

IN 91-84 a

December 26, 1991 Case 3: A licensee experienced an activation

system, but no criticality accident of the plant's criticality alarm

had

found that the alarm had been generated actually occurred. Investigation

supply (UPS) circuit that powered the when the uninterruptable power

a switch in the facility's main computer alarm system was turned off by means of

to the system to allow for cutoff of room. The switch had been backfitted

all

emergency situations and was not intended power to the computer room in

alarm system. The modification review to affect power to the criticality

switch did not identify the fact that associated with the addition of the

source and the primary criticality alarm the planned location was between the UPS

system circuit.

Case 4: During an electrical storm, the criticality

the Waste Treatment Facility (WTF) sounded safety alarms at only

interruption. Personnel in the WTF because of a momentary power

Security, who then notified Radiation did not evacuate, but instead called

Electricians then entered the WTF to Control and Electrical Shop personnel.

silence the alarms before obtaining

clearance from Radiation Control.

that the personnel in the WTF did notAn investigation of the incident determined

required by 10 CFR 70.24, and that evacuate in accordance with procedures

the

into the WTF to silence the alarms priorelectricians made an uncontrolled entry

Control. to getting clearance from Radiation

Case 5: During a routine NRC inspection of a

monitoring system, the inspector found licensee's criticality accident

been performed to demonstrate that the that: (1) since 1970, no evaluation had

coverage for facility modifications system provided adequate monitoring

special nuclear material were being or additions where large quantities

stored or used; (2) the licensee did of

have a system to ensure that such technical not

documented; and (3) no program existed evaluations were performed and

shielding materials between the neutron to limit the storage of intervening

areas. criticality detectors and the monitored

Case 6: During maintenance, a licensee discovered

accident conditions (greater than 1 that under design basis'

E+15 fissions) its criticality alarm

system might not function as intended.

detectors that could become electronically The alarm system used Geiger-Mueller

field and not function. As a result, saturated in a high radiation

and discontinued transfers of fissile the licensee declared an Unusual Event

licensee terminated the Unusual Event materials within the facility. The

circuitry to the criticality alarm system.after connecting anti-saturation

Discussion

All licensees are reminded of the importance

criticality detection, monitoring, and of maintaining operable

procedures and training for response annunciation capabilities, as well as

to criticality alarms. As the forementioned

cases indicate, a lack of detailed knowledge

routing of detector or power circuits of the system's configuration and

can

possible impact of installation, modification, result in failure to recognize the

the criticality alarm system. Physical or maintenance activities on

and electrical modifications have the

S 4

I

IN 91-84 December 26 1991 clear potential to degrade or disable all or part of this important safety

system. Licensees should ensure that they have established a comprehensive

testing program, both on a routine basis and after maintenance and modification

activities, and a method of continuously monitoring the integrity of

criticality alarm system lines and components, through line supervision, to preclude failure of criticality alarm system capabilities. These activities

should include clearly written implementing procedures, and a training program

to ensure appropriate implementation.

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

you have questions about the information in this notice, please contact one of

the technical contacts listed below or the appropriate regional office.

Richard E. Cunningham, Director

Division of Industrial and

Medical Nuclear Safety, NMSS

Technical contacts: Scott Pennington, NMSS

(301) 504-2693 Gerald Troup, RII

(404) 331-5566 Attachments:

1. List of Recently Issued NMSS Information Notices

2. List of Recently Issued NRC Information Notices

i 4 .

K>~

Attachment 1 IN 91-84 December 26, 1991 LIST OF RECENTLY ISSUED

NMSS INFORMATION NOTICES

Intormation Date ot

Notice No. Subject Issuance Issued to

91-71 Training and Supervision 11/12/91 All NRC medical licensees.

of Individuals Supervised

by an Authorized User

91-66 (1) Erroneous Data in 10/18/91 All fuel cycle licensees,

"Nuclear Safety Guide, critical mass licensees, TID-7016, Revision 2," interim spent fuel storage

(NUREG/CR-0095, ORNL/ licensees, and all holders

NUREG/CSD-6 (1978)) and of operating licenses or

(2) Thermal Scattering construction permits for

Data Limitation in the test, research, and nuclear

Cross-Section Sets Provided power reactors.

with the KENO and SCALE Codes

91-65 Emergency Access to 10/16/91 All NRC licensees.

Low-Level Radioactive

Waste Disposal Facilities

91-60 False Alarms of Alarm 09/24/91 All Nuclear Regulatory Com- Ratemeters Because of mission (NRC) licensees

Radiofrequency Interference authorized to use sealed

sources for industrial

radiography

91-49 Enforcement of Safety 08/15/91 All Nuclear Regulatory Com- Requirements for Radiographers mission (NRC) licensees

authorized to use sealed

sources for industrial radi- ography.

91-44 Improper Control of Chemicals 07/07/91 All nuclear fuel facilities.

in Nuclear Fuel Fabrication

91-39 Compliance with 10 CFR 06/17/91 All Nuclear Regulatory

Part 21, "Reporting of Defects Commission (NRC) material

and Noncompliance" licensees.

91-35 Labeling Requirements for 06/07/91 All U.S. Nuclear Regulatory

Transporting Multi-Hazard Commission (NRC) licensees.

Radioactive Materials

l Attachment 2 IN 91-84 December 26, 1991 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

91-83 Solenoid-Operated Valve 12/20/91 All holders of OLs or CPs

Failures Resulted in for nuclear power reactors.

Turbine Overspeed

91-18, High-Energy Piping Failures 12/18/91 All holders of OLs or CPs

Supp. 1 Caused by Wall Thinning for nuclear power reactors.

91-82 Problems with Diaphragms 12/18/91 All holders of OLs or CPs

in Safety-Related Tanks for nuclear power reactors.

91-81 Switchyard Problems that 12/16/91 All holders of OLs or CPs

Contribute to Loss of for nuclear power reactors.

Offsite Power

91-80 Failure of Anchor 12/11/91 All holders of OLs or CPs

Head Threads on Post- for nuclear power reactors.

Tensioning System During

Surveillance Inspection

91-79 Deficiencies in the 12/06/91 All holders of OLs or CPs

Procedures for Instal- for nuclear power reactors.

ling Thermo-Lag Fire

Barrier Materials

88-92, Potential for Spent 11/29/91 All holders of OLs or CPs

Supp. 1 Fuel Pool Draindown for nuclear power reactors.

91-78 Status Indication of 11/28/91 All holders of OLs or CPs

Control Power for for nuclear power reactors.

Circuit Breakers Used

in Safety-Related Appli- cations

90-57, Substandard, Refur- 11/27/91 All holders of OLs or CPs

Supp. 1 bished Potter & Brum- for nuclear power reactors.

field Relays Repre- sented as New

OL = Operating License

CP = Construction Permit