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, 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, 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, Crane
Issue date:	12/26/1991
Revision:	0
From:	Cunningham R E NRC/NMSS/IMNS
To:
References
IN-91-084, NUDOCS 9112190113
Download: ML031190217 (5)

UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDSWASHINGTON, D.C. 20555December 26, 1991NRC INFORMATION NOTICE 91-84: PROBLEMS WITH CRITICALITY ALARMCOMPONENTS/SYSTEMS

Addressees

AllNuclear Regulatory Commission (NRC) fuel cycle licensees, interim spentfuel storage licensees, and critical mass licensees.

Purpose

NRC is issuing this notice to remind licensees of the importance of adequatereviews of plant modification, installation, maintenance, and response actions,to ensure that required criticality alarm systems meet their intended purpose.It is expected that recipients will review this information for applicabilityto their facilities, distribute it to responsible staff, and consider actions,-as appropriate, to avoid similar problems. However, suggestions contained inthis information notice do not constitute any new NRC requirements, and nowritten response is required.

Description of Circumstances

The following cases are recent events involving problems with licensee'scriticality alarm systems that have been reported to, or discovered by, NRC.Case 1: During a routine test of the criticality alarm system, a licenseediscovered that several of the site's audible alarms ("howlers") did notactuate. The licensee found that wiring to the alarms had been accidentallybroken while other electrical cables were being pulled through the cable runthat contained the criticality alarm wiring. The licensee's system providedindication, prior to the next scheduled test, that some of-the audible alarmshad been disabled.Case 2: Engineering drawings describing modifications at a licensed facilityspecified removal of "heat detectors (radiation)." The licensee's review ofthe modification package did not recognize that it included removal, ratherthan relocation, of criticality alarm system detectors. When the specifieddetectors were removed no alarm was generated at the system monitoring panel.Subsequent investigation disclosed that the alarm panel was wired in such away that, although a "failure" light was activated at an intermediate panel (anunmanned location), a "loss of power/loss of detector" signal was not generatedat the monitoring panel in a normally manned area.9112190113 R I t I c)VI0020980,F -_

IIIIN 91-84 aDecember 26, 1991 Case 3: A licensee experienced an activation of the plant's criticality alarmsystem, but no criticality accident had actually occurred. Investigationfound that the alarm had been generated when the uninterruptable powersupply (UPS) circuit that powered the alarm system was turned off by means ofa switch in the facility's main computer room. The switch had been backfittedto the system to allow for cutoff of all power to the computer room inemergency situations and was not intended to affect power to the criticalityalarm system. The modification review associated with the addition of theswitch did not identify the fact that the planned location was between the UPSsource and the primary criticality alarm system circuit.Case 4: During an electrical storm, the criticality safety alarms at onlythe Waste Treatment Facility (WTF) sounded because of a momentary powerinterruption. Personnel in the WTF did not evacuate, but instead calledSecurity, who then notified Radiation Control and Electrical Shop personnel.Electricians then entered the WTF to silence the alarms before obtainingclearance from Radiation Control. An investigation of the incident determinedthat the personnel in the WTF did not evacuate in accordance with proceduresrequired by 10 CFR 70.24, and that the electricians made an uncontrolled entryinto the WTF to silence the alarms prior to getting clearance from RadiationControl.Case 5: During a routine NRC inspection of a licensee's criticality accidentmonitoring system, the inspector found that: (1) since 1970, no evaluation hadbeen performed to demonstrate that the system provided adequate monitoringcoverage for facility modifications or additions where large quantities ofspecial nuclear material were being stored or used; (2) the licensee did nothave a system to ensure that such technical evaluations were performed anddocumented; and (3) no program existed to limit the storage of interveningshielding materials between the neutron criticality detectors and the monitoredareas.Case 6: During maintenance, a licensee discovered that under design basis'accident conditions (greater than 1 E+15 fissions) its criticality alarmsystem might not function as intended. The alarm system used Geiger-Muellerdetectors that could become electronically saturated in a high radiationfield and not function. As a result, the licensee declared an Unusual Eventand discontinued transfers of fissile materials within the facility. Thelicensee terminated the Unusual Event after connecting anti-saturationcircuitry to the criticality alarm system.DiscussionAll licensees are reminded of the importance of maintaining operablecriticality detection, monitoring, and annunciation capabilities, as well asprocedures and training for response to criticality alarms. As the forementionedcases indicate, a lack of detailed knowledge of the system's configuration androuting of detector or power circuits can result in failure to recognize thepossible impact of installation, modification, or maintenance activities onthe criticality alarm system. Physical and electrical modifications have theS 4 IIN 91-84December 26 1991 clear potential to degrade or disable all or part of this important safetysystem. Licensees should ensure that they have established a comprehensivetesting program, both on a routine basis and after maintenance and modificationactivities, and a method of continuously monitoring the integrity ofcriticality alarm system lines and components, through line supervision,to preclude failure of criticality alarm system capabilities. These activitiesshould include clearly written implementing procedures, and a training programto ensure appropriate implementation.This information notice requires no specific action or written response. Ifyou have questions about the information in this notice, please contact one ofthe technical contacts listed below or the appropriate regional office.Richard E. Cunningham, DirectorDivision of Industrial andMedical Nuclear Safety, NMSSTechnical contacts: Scott Pennington, NMSS(301) 504-2693Gerald Troup, RII(404) 331-5566

Attachments:

1. List of Recently Issued NMSS Information Notices2. List of Recently Issued NRC Information Notices K>~i 4 .Attachment 1IN 91-84December 26, 1991 LIST OF RECENTLY ISSUEDNMSS INFORMATION NOTICESIntormation Date otNotice No. Subject Issuance Issued to91-7191-6691-6591-6091-4991-4491-3991-35Training and Supervision 11/12/91 All NRC medical licensees.of Individuals Supervisedby an Authorized User(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 holdersNUREG/CSD-6 (1978)) and of operating licenses or(2) Thermal Scattering construction permits forData Limitation in the test, research, and nuclearCross-Section Sets Provided power reactors.with the KENO and SCALE CodesEmergency Access to 10/16/91 All NRC licensees.Low-Level RadioactiveWaste Disposal FacilitiesFalse Alarms of Alarm 09/24/91 All Nuclear Regulatory Com-Ratemeters Because of mission (NRC) licenseesRadiofrequency Interference authorized to use sealedsources for industrialradiographyEnforcement of Safety 08/15/91 All Nuclear Regulatory Com-Requirements for Radiographers mission (NRC) licenseesauthorized to use sealedsources for industrial radi-ography.Improper Control of Chemicals 07/07/91 All nuclear fuel facilities.in Nuclear Fuel FabricationCompliance with 10 CFR 06/17/91 All Nuclear RegulatoryPart 21, "Reporting of Defects Commission (NRC) materialand Noncompliance" licensees.Labeling Requirements for 06/07/91 All U.S. Nuclear RegulatoryTransporting Multi-Hazard Commission (NRC) licensees.Radioactive Materials lAttachment 2IN 91-84December 26, 1991 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to91-8391-18,Supp. 191-8291-8191-8091-7988-92,Supp. 191-7890-57,Supp. 1Solenoid-Operated ValveFailures Resulted inTurbine OverspeedHigh-Energy Piping FailuresCaused by Wall ThinningProblems with Diaphragmsin Safety-Related TanksSwitchyard Problems thatContribute to Loss ofOffsite PowerFailure of AnchorHead Threads on Post-Tensioning System DuringSurveillance InspectionDeficiencies in theProcedures for Instal-ling Thermo-Lag FireBarrier MaterialsPotential for SpentFuel Pool DraindownStatus Indication ofControl Power forCircuit Breakers Usedin Safety-Related Appli-cationsSubstandard, Refur-bished Potter & Brum-field Relays Repre-sented as New12/20/9112/18/9112/18/9112/16/9112/11/9112/06/9111/29/9111/28/9111/27/91All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.OL = Operating LicenseCP = Construction Permit