Information Notice 2005-05, Improving Material Control and Accountability Interface with Criticality Safety Activities at Fuel Cycle Facilities

Improving Material Control and Accountability Interface with Criticality Safety Activities at Fuel Cycle Facilities

ML050590234
Person / Time
Issue date:	03/10/2005
From:	Pierson R C NRC/NMSS/FCSS
To:
References
IN-05-005
Download: ML050590234 (5)

UNITED STATES NUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDSWASHINGTON, DC 20555March 10, 2005NRC INFORMATION NOTICE 2005-05:IMPROVING MATERIAL CONTROL ANDACCOUNTABILITY INTERFACE WITH

CRITICALITY SAFETY ACTIVITIES AT FUEL

CYCLE FACILITIES

ADDRESSEES

All licensees authorized to possess a critical mass of special nuclear material.

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to informaddressees of a safety concern related to criticality safety at fuel fabrication and other facilitiesprocessing, storing, or handling critical masses of fissile material. The safety concern arises

when licensees fail to establish and maintain a communication process between criticality

safety staff and material control and accountability (MC&A) staff, in order to support timelyidentification of fissile material-related process upsets that challenge the criticality safety basisfor the facility. It is expected that licensees will review this information and consider actions, asappropriate, to avoid similar problems. Suggestions contained in this IN are not NRC

requirements; therefore, no specific action nor written response is required.

DESCRIPTION OF CIRCUMSTANCES

Under 10 CFR Parts 70 and 76, certain licensees processing, storing, or handling criticalmasses of fissile material are required to analyze accident scenarios leading to criticality and

provide reliable controls to assure that inadvertent criticality events are highly unlikely. Recently, a licensee reported an event, to the NRC, concerning operation of an incineratoroutside of the approved safety basis. The licensee had performed a criticality safety evaluation

of the incinerator approximately 8 years previously and had concluded that criticality was not

credible outside of the primary combustion chamber. The licensee nuclear criticality safety (NCS) analysis focused on accumulation of sufficientmass in the incinerator system to support criticality. Licensee NCS engineers concluded thatvery limited amounts of ash would carry over from the incinerator primary combustion chamber

to the remainder of the incinerator system and that mass controls on the primary combustionchamber would limit uranium concentration in the ash to less than 21.6 percent throughout the

incinerator system. This led the licensee's NCS engineers to conclude that criticality outsidethe primary combustion chamber was not credible due to normal operations and

expected upsets. At the time that this NCS analysis was approved, licensee MC&A staff possessed samplingdata showing concentration levels above 21.6 percent uranium in some parts of the incinerator

system. In addition, licensee MC&A staff were aware, from approximately 15 years ofoperational experience, that substantial amounts of fissile material routinely accumulated inparts of the incinerator system where criticality analysis assumed minimal accumulation.The material accumulation event was identified initially when a licensee criticality safetyengineer reviewed MC&A sampling data. Subsequent investigation of the event by the licenseerevealed that ash deposits at various locations in the incinerator routinely exceeded the 21.6 percent uranium concentration assumed to be bounding for ash and that the mass of ashdeposited also exceeded expectations. Licensee review of MC&A sampling records confirmed

that both concentration and deposit information were known prior to approval of the original

NCS analysis.The amount of fissile material that accumulated in the uncontrolled parts of the incineratorsystem exceeded a critical mass. Extensive investigation by the licensee and the NRCrevealed a poor interface between licensee criticality safety and MC&A staff. This poor

interface, resulting from failing to require routine interaction, apparently was a factor in the

failure to identify the process upset before the event occurred.Discussion

Two issues from this event are of concern to the NRC. The first issue is that licensee NCS staffhad not ensured that MC&A staff were familiar with the criticality safety basis for the incineratorsystem. Specifically, MC&A staff were not aware of the basic assumption that fissile material

would not accumulate in the upper chamber or flue. Had MC&A staff been made aware of this

assumption, they would likely have identified the reality of incinerator ash deposition and

caused the NCS staff to place additional criticality controls on at least those two sections of the

incinerator system.The second issue is that the MC&A sampling data routinely reported mass and concentrationvalues that challenged the criticality safety basis, and this fact was not recognized by criticality

safety engineers because the data were not routinely provided to them.Licensee NCS staff are familiar with the criticality safety basis and underlying assumptions. MC&A staff have a general knowledge of where material is currently located and where process

hold-up is likely to occur. Communication between these two organizations is necessary to

assure that the criticality safety basis is not violated.Failure to establish appropriate interactions between criticality safety and MC&A staff exposesfuel cycle licensees to this type of programmatic failure. Licensees should consider actions, asappropriate, to mitigate this vulnerability. NCS staff should be familiar with MC&A samplingmethodology and data reporting and should routinely review MC&A reports for location of

material in relation to the criticality safety basis. MC&A staff should be trained on the criticality safety basis, particularly bounding assumptions about fissile material accumulation, and shouldroutinely review new or changed NCS analyses.This IN requires no specific action nor written response. If you have any questions about theinformation in this notice, please contact the technical contact listed below./RA/Robert C. Pierson, DirectorDivision of Fuel Cycle Safety

and Safeguards

Office of Nuclear Material Safety

and Safeguards

Technical Contact:

Dennis Morey, NMSS301-415-6107 e-mail: dcm@nrc.govAttachment: List of Recently Issued NMSS Generic Communications safety basis, particularly bounding assumptions about fissile material accumulation, and shouldroutinely review new or changed NCS analyses.This IN requires no specific action nor written response. If you have questions about the information in this notice, please contact the technical contact listed below./RA/Robert C. Pierson, DirectorDivision of Fuel Cycle Safety

and Safeguards

Office of Nuclear Material Safety

and Safeguards

Technical Contact:

Dennis Morey, NMSS301-415-6107 e-mail: dcm@nrc.govAttachment: List of Recently Issued NMSS Generic ComminicationsML050590234OFCTSGFCFBTech EDTSGNSIRNAMEDMorey:dwJMuszkiewiczEkraus: by faxMGallowayMWilliamsDATE2/ 22 /053/ 01 /052/ 28 /052/ 28 /053/ 09 /05OFCFCSSNAMERPiersonDATE3/ 10 /05 Attachment Recently Issued NMSS Generic ComminicationsDateGC No.Subject

Addressees

12/16/2004RIS-04-020

NRC Regulatory issueSummary 2004-20:

Lessons Learned from

Review of 10 CFR Parts 71 and 72 ApplicationsAll holders of, and applicants for,a (1) 10 CFR Part 71 certificate

of compliance for a radioactive

material transportation package;

(2) 10 CFR Part 72 cretificate of

compliance for a spent fuel

storage cask; and (3) 10 CFR

Part 72 specific license for an

independent spent fuel storage

installation (ISFSI).12/01/2004RIS-04-018 NRC Regulatory IssueSummary 2004-18:

Expiration Date for 10 CFR

Part 71 Quality Assurance

Program ApprovalsAll holders of U.S. NuclearRegulatory Commission (NRC)-approved 10 CFR Part 71 Quality

Assurance Programs (QAPs).11/23/2004RIS-04-017 NRC Regulatory IssueSummary 2004-17:

Revised Decay-in-Storage

Provisions for the Storage

of Radioactive Waste

Containing Byproduct

MaterialAll licensees regulated under 10CFR Parts 30, 32, 33, and 50.10/26/2004IN-04-018Recent Safety-RelatedEvent at Panoramic

Wet-source-Storage

IrradiatorAll licensees authorized to possess and use sealed sources

in panoramic wet-source-storage

irradiators, and irradiator

vendors.07/19/2004IN-04-014Use of less than OptimalBounding Assumptions

in Criticality Safety Analysis

at Fuel Cycle FacilitiesAll licensees authorized topossess a critical mass

of special nuclear material Note: NRC generic communications may be found on the

NRC public website,http://www.nrc.gov, under Electronic Reading Room/Document Collections.