Information Notice 1992-14, Uranium Oxide Fires at Fuel Cycle Facilities

Uranium Oxide Fires at Fuel Cycle Facilities

ML031200616
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:	02/21/1992
Revision:	0
From:	Cunningham R E NRC/NMSS/IMNS
To:
References
IN-92-014, NUDOCS 9202190037
Download: ML031200616 (11)

UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDSWASHINGTON, D.C. 20555February 21, 1992NRC INFORMATION NOTICE 92-14: URANIUM OXIDE FIRES AT. FUEL CYCLE FACILITIES

Addressees

All fuel cycle and uranium fuel research and development licensees.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert addressees to the potential for fires involving uranium dioxide(UO2) powder at various stages of transfer and conversion. It is expected thatrecipients will review the information for applicability to their facilitiesand consider actions, as appropriate, to avoid similar problems. However,suggestions contained in this information notice are not new NRC requirements;therefore, no specific action or written response is required.

Description of Circumstances

In licensed fuel-fabrication facilities, there have been one recent and severalpast incidents of fires involving uranium at various stages of oxidation. Thecircumstances of two of them are described below in some detail.Incident 1:In the most recent incident, a fire was discovered, in a fuel-fabricationfacility, involving a hood, hopper, and feed-screw assembly, which wasbeing used to transfer calciner drop powder (uranium oxide) to a nitricacid dissolver tank. (See Figure 1.) According to a report submitted bythe licensee, an operator had started to feed a batch of the powder intothe dissolver tank when the feed-screw of the Model 608 Accu-Rate feederstopped. The operator reversed the screw and tapped on the tube-shapednylon screw-housing, to free the screw. At this time, he observed smokeand sparks coming out of the equipment below the hood. A small crack inthe vinyl side of the feeder hopper, apparently the result of contactwith the hot powder inside the hopper, was also noticed. The operatorand other employees then donned full-face respirators and removedapproximately 18 kg of the powder, leaving about 2 kg of powder thatcould not be removed, in the screw-housing. Meanwhile, the small crackon the side of the hopper had developed into a baseball-sized hole,spilling some powder onto a platform below. The employees cleaned up thespilled powder. Assuming that the incipient fire had been extinguished,the employees then left the area.92029037_/oA A 'VIA ajit eq o32 ra Ads Dik 111.92-14February 21, 1992 Approximately one hour later, fire alarm bells sounded throughout the plant,and the source of the fire was determined to be the same hood and feederassembly that the employees had been working on. When plant emergency teammembers, dressed in protective clothing and using self-contained breathingapparatuses, entered the room, they found the visibility reduced to about1 or 2 feet, because of the heavy smoke. Using portable dry chemical andcarbon dioxide fire extinguishers, they extinguished the fire within 15minutes of the alarm bells sounding.All components of the hood and the Accu-Rate feeder that were made ofcombustible material (e.g., the nylon feed tube, vinyl hopper, rubber partsof a valve, and "Lexan" faces of the hood) were consumed by the fire. Theprimary stage of the high-efficiency particulate air (HEPA) filter for theroom was loaded with soot, and the pre-filter was burnt. The fire alarmbells stopped ringing after about 3 minutes, as the alarm circuitry in theroom was damaged by the fire. This confused some employees, who could nottell whether the emergency was over.The incident exposed a weakness in the emergency communications systembetween the licensee and the local city fire department. Shortly beforethe incident, the facility had tested a newly installed extension of itsfire alarm system, in conjunction with the fire department. Even thoughthe facility had notified the fire department that the test was over, thefire department mistook the alarm, which came in about 18 minutes later, tobe merely a continuation of the test. A 911 call was needed to alert themof the real emergency. Precious minutes were lost. Fortunately, by thetime the fire department arrived, the plant emergency team had suppressedthe fire.In other observations, some employees thought that the alarm bells in someareas were not loud enough. Voice communications over the public addresssystem were misunderstood by some employees and not heard by others,especially in the office areas.The cause of the fire is believed to be the oxidation of the calciner droppowder consisting principally of uranium dioxide (U02), but also includingother unstable oxides of uranium, which could further oxidize at elevatedtemperatures. The friction of the feed-screw sliding on the powder or onthe nylon tube, which could have been warped, could conceivably havecontributed to heating the powder.Incident 2:In another incident, at another nuclear fuel-fabrication facility, a firewas reported to have occurred in a slugger press containment housing. Inthis configuration, uranium oxide powder, following a blending process,was gravity-fed from a second floor hammermill baghouse through a 4-inchdiameter x 6-foot long "Viton" hose to a first floor slugger press. TheViton hose was connected to the slugger press shuttle by a "Neoprene"boot. The slugger press shuttle area, including the Viton hose and the IN 92- 14February 21, 1992 Neoprene boot, was enclosed by the containment housing, which had twoLexan panels for access to the shuttle area. Containment ventilation wasprovided through primary and secondary HEPA filters and a water scrubberbefore exhausting to the environment.In this incident, the operator noticed that the granulator downstream ofthe slugger was not discharging powder. Apparently, this was not anunusual occurrence, and he started to arrange for replacement of thegranulator screen, as was the normal practice. He then noticed a fire inthe slugger housing. The ventilation system smoke detector had by thattime sensed the fire and alarm bells were sounding. Employees extinguishedthe fire within minutes using portable carbon dioxide fire extinguishers.All of the combustible elements in the containment between the hammermilland the slugger press (e.g., the Viton hose and the Neoprene boot, as wellas the Lexan parts of the containment housing) were consumed by the fire.The primary HEPA filters were extensively damaged. The secondary filters,however, were intact. In this case, also, heat generated by oxidation ofthe powder, which ignited the Neoprene boot, was judged to be the cause ofthe fire.In other incidents, dating back to 1977, several fires involving calcinerdischarge lines and at least one involving a hammermill hood have been reported.In all cases, the oxidizing uranium powder was believed to be the source ofignition, and combustible materials, such as transfer hoses and boots, providedthe fuel. All the fires were promptly extinguished.DiscussionIt has been common experience that unstable uranium oxide feed material(comprised mostly of U02, with a few other oxide forms present) in granulatedform and in contact with oxygen undergoes exothermic oxidation-reactions. Insome cases, the heat generated by the reactions ignites combustible elementsof the transfer passages or other powder-handling equipment (e.g., hoses, boots,etc.), which then contribute fuel to the fire. The fires described above havethis commonality of cause and effect. -The fuel fabrication process generates several oxides of uranium. The finaland most stable oxide is U02.The literature on uranium chemistry describesoxidation reactions that are complex, with their rates, heat evolution, andfinal products depending on several parameters, but most importantly on thefineness of the powder and the temperature. Indeed, according to one author*,normally stable U02 may-be pyrophoric or oxidize rapidly even at roomtemperatures when in very fine powder form (specific surface area >10 m2/g).Coarser powders, as is more commonly the case, .may require elevated temperatures(>3000C) to oxidize. The account of the most recent fire suggests that elevatedtemperatures may have been generated by the Accu-Rate feed-screw binding on itsnylon housing. -Friction of the granulated material in motion may also havegenerated heat that raised the temperature.* Cordfunke, E.H.P., The Chemistry of Uranium, Elsevier Publishing Company, 196 IN 92-14February 21, 1992 Since, by the very nature of the manufacturing process, unstable uranium powdermust be handled, certain preventive measures should be taken in order to reducethe potential for fires; and many of these have been adopted at licensedfacilities. They are:1. Limit the type of feed to stable powder whenever possible.2. Store unstable powder in closed metal containers.3. Replace the combustible components of powder-transfer lines and ofequipment, such as the Accu-Rate feeder, with components made ofnoncombustible materials, as far as practicable.4. Require an operator to be present when a process is under way, and improvevisibility around vulnerable equipment.5. Incorporate fire safety of vulnerable equipment in the operator trainingprogram, including use of portable fire extinguishers.6. Implement a preventive maintenance program for vulnerable equipment.Periodic inspection may alert the operator to telltale signs ofoverheating.Additionally, the following measures for upgrading the fire detection, alarm,and suppression systems may be considered:1. Install fire detectors in hoods and equipment exhaust ducts. Thesedetectors should be connected to a central panel, which is continuouslysupervised.2. Check alarm system wiring for vulnerability to fire and reroute, ifnecessary and feasible. Implement a manual restart procedure, if alarmcircuitry is partially disabled and the alarm stops.3. Upgrade the alarm system and public address system for audibility, ifnecessary.4. Add visible alarm signals in noisy areas.5. Install carbon dioxide total flooding or local application system inequipment enclosure. For use and limitations of such systems, seeNFPA-12, "Standard on Carbon Dioxide Extinguishing Systems," published bythe National Fire Protection Association. This should not preclude theavailability of portable fire extinguishers of both carbon dioxide and drychemical types.Some lessons on emergency communications may be learned from Incident 1 above.Some protocol should be established between the facility and the offsite firedepartment so that emergency calls are not misunderstood. Licensees shouldconsider reviewing this information notice with their local fire department.The public address system announcement of an emergency and related directives IN 92-14February 21, 1992 should follow standard wording that is familiar to all employees and minimizesmisunderstandings.Fuel cycle licensees should review the Branch Technical Position (BTP) on FireProtection for Fuel Cycle Facilities, published in the Federal Register(54 FR 11590-98) dated March 21, 1989. Licensees should examine theirfacilities, procedures, and records to assure that the stipulations of the BTPare met or exceeded.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate regional office.Richard E. Cunningham, DirectorDivision of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand SafeguardsTechnical contacts:Amar Datta, NMSS(301) 504-2536Charles H. Robinson, NMSS(301) 504-2576.-.I

Attachments:

'k" /1. Figure 12. List of Recently Issued NRC Information Notices3. List of Recently Issued NMSS Information Notices IN 92-14February 21, 1992 should follow standard wording that is familiar to all employees and minimizesmisunderstandings.Fuel cycle licensees should review the Branch Technical Position (BTP) on FireProtection for Fuel Cycle Facilities, published in the Federal Register(54 FR 11590-98) dated March 21, 1989. Licensees should examine theirfacilities, procedures, and records to assure that the stipulations of the BTPare met or exceeded.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate regional office.Richard E. Cunningham, DirectorDivision of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand SafeguardsTechnical contacts: Amar Datta, NMSS(301) 504-2536Charles H. Robinson, NMSS(301) 504-2576

Attachments:

1. Figure 12. List of Recently Issued NRC Information Notices3. List of Recently Issued NMSS Information NoticesEditor/NMSSEKraus1/24/92* -See previous concurrenceOFC :IMUF :IMUF :IMUF :IMUF :IMSB :IMOB :IMNS-______________________________________________________________________________NAME:ADatta/mh :CRobinson :VTharpe :GHBidinger:JHickey :KRamsey :JGreeves :-______________________________________________________________________________DATE:1/13/92* :1/13/92* :1/14/92* :1/16/92* :2/06/92*:2/06/92* :2/11/92*OFC :IMNS -eNAME:nEunnfngham:DATE:2/11/92*OFFICIAL RECORD COPYDOCUMENT NAME: IN 92-14 IN 92-February , 1992 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate regional office.Richard E. Cunningham, DirectorDivision of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand SafeguardsTechnical contacts: Amar Datta, NMSS(301) 504-2536Charles H. Robinson, NMSS(301) 504-2576

Attachments:

1. Figure 12. List of Recently Issued NRC Information Notices3. List of Recently Issued NMSS Information NoticesDISTRIBUTION:See attached checklistIMUF r/fIMSB r/fIMOB r/fIMNS r/fEditor/NMSSEKraus1/24/92* -See previous concurrenceOFC :IMUF :IMUF :IMUF :IMUF :I B :IMOS: MNSS t LbNAME:ADatta/mh :CRobinson :VTharpe :GHBidinger:Jlkey :KRamsey :JG eves_ ------------_ _ _ _ _ _ _ _ _ _ _ _ _ ---_ _ _ _ _ _ -----_ _ _ _ _ _ _ _ _ _- -----------------------DATE:1/13/92* :1/13/92* :1/14/92* :1/16/92* :21(192 :2/1i/92 :2/ 2N : Cunnngham:DATE:2//1/92OFFICIAL RECORD COPYAD/INFORMATION NOTICE IN 92(inso .Januaty 1~992-, This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate regional office.Richard E. Cunningham, DirectorDivision of Industrial andMedical Nuclear SafetyOffice of Nuclear Material Safetyand SafeguardsTechnical contacts: Amar Datta, NMSS(301) 504-2536Charles H. Robinson, NMSS(301) 504-2576

Attachments:

1. Figure 12. List of Recently Issued NRC Information Notices3. List of Recently Issued NMSS Information NoticesAD/INFORMATION NOTICEset. dAo*'TrAS1 4$V*0a~ ripI0Js r/[674@w' /1KMS5.1:f /1z-OFC:I IMUF:. -a IMUF: INAME:A41tataih: CRobinson: VT e6tidinger:DATE:1/Jf /92: 1/i3/92: 1/\'/92: 1/7(192:OFC:IMSB: DD/IMNS: D/IMNS:-______________________________________________________________________________NAME:JHickey: JGreeves: RCunningham:-______________________________________________________________________________DATE:1/ /92: 1/ /92: 1/ /92:OFFICIAL RECORD COPY to C+ C7l pa Ia 01 I-O CD 41 V,I -UDFigure 1.Uranium oxide feeder assembl Attachment 2IN 92-14February 21, 1992 LIST OF RECENTLY ISSUEDNMSS INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to92-1192-1092-0891-86Soil and Water Contamina-tion at Fuel Cycle Facil-itiesBrachytherapy IncidentsInvolving Iridium-192 WireUsed in EndobronchialTreatmentsRevised Protective ActionGuidance for Nuclear Inci-dentsNew Reporting Requirementsfor Contamination Events atMedical Facilities(10 CFR 30.50)Problems with CriticalityAlarm Components/SystemsTraining and Supervisionof Individuals Supervisedby an Authorized User(1) Erroneous Data in"Nuclear Safety Guide-,TID-7016, Revision 2,"(NUREG/CR-0095, ORNL/NUREG/CSD-6 (1978)) and(2) Thermal ScatteringData Limitation in theCross-Section Sets Providedwith the KENO and SCALE Codes02/05/9201/31/9201/23/9212/27/9112/26/9111/12/9110/18/91All uranium fuel fabrica-tion and conversion facil-ities.All Nuclear Regulatory Com-mission (NRC) licenseesauthorized to useiridium-192 for brachy-therapy; manufacturers anddistributors of iridium-192wire for use in brachy-therapy.All fuel cycle and materi-als licensees authorizedto possess large quanti-ties of radioactive materi-ial.All licensees authorizedto use byproduct materialsfor human use.All Nuclear RegulatoryCommission (NRC) fuelcycle licensees, interimspent fuel storage licens-ees, and critical masslicensees.All NRC medical licensees.All fuel cycle licensees,critical mass licensees,interim spent fuel storagelicensees, and all holdersof operating licenses orconstruction permits fortest, research, and nuclearpower reactors.91-8491-7191-66 Attachment 3IN 92-14February 21, 1992 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to92-02,Supp. 192-1392-1292-11Relap5/Mod3 Computer CodeError Associated with theConservation of EnergyEquationInadequate Control OverVehicular Traffic atNuclear Power Plant SitesEffects of Cable LeakageCurrents on InstrumentSettings and IndicationsSoil and Water Contamina-tion at Fuel Cycle Facil-itiesBrachytherapy IncidentsInvolving Iridium-192 WireUsed in EndobronchialTreatmentsOverloading and SubsequentLock Out of ElectricalBuses During AccidentConditionsRevised Protective ActionGuidance for Nuclear Inci-dents02/18/9202/18/9202/10/9202/05/9201/31/9201/30/9201/23/9292-10All 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 uranium fuel fabrica-tion and conversion facil-ities.All Nuclear Regulatory Com-mission (NRC) licenseesauthorized to useiridium-192 for brachy-therapy; manufacturers anddistributors of iridium-192wire for use in brachy-therapy.All holders of OLs or CPsfor nuclear power reactors.All fuel cycle and materi-als licensees authorizedto possess large quanti-ties of radioactive materi-ial.92-0992-08OL = Operating LicenseCP = Construction Permit