Information Notice 2007-30, Radiological Controls Create Criticality Safety Accident Scenario for Fissile Solution Container Transport at Fuel Cycle Facility

Radiological Controls Create Criticality Safety Accident Scenario for Fissile Solution Container Transport at Fuel Cycle Facility

ML072500291
Person / Time
Issue date:	09/13/2007
From:	Pierson R NRC/NMSS/FCSS
To:
References
IN-07-030
Download: ML072500291 (8)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555 September 13, 2007 NRC INFORMATION NOTICE 2007-30: RADIOLOGICAL CONTROLS CREATE

CRITICALITY SAFETY ACCIDENT SCENARIO

FOR FISSILE SOLUTION CONTAINER

TRANSPORT AT FUEL CYCLE FACILITY

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 inform

addressees of a criticality safety concern regarding wrapping fissile solution filled vessels with

plastic, for radiological control, while transporting the vessels within fuel cycle facilities. NRC

expects that licensees will review this information and consider actions, as appropriate, 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

An NRC licensee operates a fuel cycle facility that processes and stores high-enriched uranium

(HEU) in both solid and solution form. To clean floors in contaminated areas of the facility, the

licensee typically places cleaning solution on the floor, scrubs the floor with an orbital scrubber, and then removes the solution with a large workshop-type vacuum cleaner. The vacuum

cleaners have a volume of approximately 52 liters (14 gallons) and are filled with raschig rings, to allow any solution in the facility to be vacuumed from the floor. The raschig ring-filled vacuum

cleaners are occasionally used to recover from large spills when collection of solution with

sponges would be too slow. Concentrated HEU solutions containing up to 400 grams per liter of

Uranium-235 (U-235) are allowed in raschig ring-filled vessels in the facility and such solutions

have been transferred into the raschig ring-filled vacuum cleaners.

The licensee uses forklifts to transport the raschig ring-filled vacuum cleaners to various

locations in the facility for floor cleaning. Most areas of the facility do not have equipment to

remove and process floor cleaning solutions, so the licensee transports filled vacuum cleaners

to another area to remove and process the contents. The licensee procedure for moving the

raschig ring-filled vacuum cleaners involved: (1) removing the vacuum pump; (2) covering the

vacuum cleaner vessel; (3) wrapping the vacuum cleaner vessel with two 55-gallon plastic bags;

and (4) moving the wrapped vacuum cleaner with a fork lift by means of brackets welded to the

vacuum cleaner frame (see Figure 1). Some of the raschig ring-filled vacuum cleaners in the

licensee facility had the lifting brackets, some did not have the brackets, and the lifting brackets

were not required to move the vacuum cleaners.

Figure 1 Rashig Ring-filled Vacuum Cleaner Vessel with Lifting Brackets

A raschig ring-filled vacuum cleaner was requested to be moved to a specified location for a

cleaning operation. The vacuum cleaner selected and wrapped for transport did not have the

lifting brackets. During the operation to move the vacuum cleaner without lifting brackets, a

licensee forklift operator picked up the vacuum with one forklift tine. The vacuum cleaner was

removed from one area and carried to another area while another licensee operator balanced

the vacuum cleaner on the single tine. At a doorway ramp near the destination, the vacuum

cleaner fell off the forklift. A large fraction of the raschig rings spilled from the vacuum cleaner

vessel and were retained by the inner wrapper. Most of the HEU solution in the vacuum cleaner

vessel, approximately 18 liters (5 gallons), spilled from the vessel and was captured between

the inner and outer wrappers, effectively separating the solution from the raschig rings. The

risk-significance of the resulting upset condition was low because the concentration of the HEU

solution was less than one gram per liter. Figure 2 Dropped Raschig Ring-filled Vacuum Cleaner Final Position

Figure 2 shows the position of the dropped vacuum cleaner vessel. The vessel is halfway up

the entrance ramp to the destination, with the top edge of the vessel lying at the edge of the

ramp. The raschig rings and solution have spilled from the vessel out over the edge of the ramp

which is approximately 3 to 4 inches high in that area. The double wrapped configuration and

the final resting position hanging over the edge of the ramp have combined to create an

unfavorable geometry vessel for the solution. Hanging downward allows a plastic bag or

wrapper to assume a more unfavorable geometry than would be likely if the final resting position

were a flat floor.

Subsequent investigation of the event revealed that: (1) no controls limited the concentration of

solution in the vacuum cleaners; (2) raschig ring-filled vacuum cleaners were commonly

transported while full of HEU solution; (3) licensee criticality safety staff did not routinely review

radiological control procedures; (4) licensee criticality safety staff were unaware that the vacuum

cleaners were transported while filled with solution; and (5) the licensee had not analyzed or

controlled the transport process with respect to criticality safety.

DISCUSSION

Licensee criticality safety engineers indicated that, had they known that the raschig ring-filled

vessels were being transported while filled with solution, they would have implemented controls

to limit the uranium content of the vessels. Such controls might have included placing limits on

solution concentration during transport, sampling the vessels before movement, or requiring a

specific transport configuration.

The NRC is concerned that licensees recognize and completely analyze all potential accident

sequences at their facilities. To this end, fuel cycle licensees typically require that criticality

safety staff review procedures associated with movement of fissile material, including

radiological control procedures.

The failure to review in-plant transport procedures and radiological controls can lead to the

creation of an unanticipated accident sequence. NRC criticality safety inspections typically

include review of the licensee criticality safety audit program, to ensure that analytical

assumptions are regularly reviewed in all areas. NRC criticality safety inspections routinely

review licensee facility operations to ensure that credible accident sequences have been

identified, analyzed, and controlled.

CONTACT

This information notice does not require any specific action or written response. Please direct

any questions about this matter to the technical contact below.

/RA/

Robert C. Pierson, Director

Division of Fuel Cycle Safety

and Safeguards

Office of Nuclear Material Safety

and Safeguards

Dennis Morey, NMSS

301-492-3112 E-mail: dcm@nrc.gov

Enclosure:

List of Recently Issued FSME/NMSS Generic Communications

DISCUSSION

Licensee criticality safety engineers indicated that, had they known that the raschig ring-filled

vessels were being transported while filled with solution, they would have implemented controls

to limit the uranium content of the vessels. Such controls might have included placing limits on

solution concentration during transport, sampling the vessels before movement, or requiring a

specific transport configuration.

The NRC is concerned that licensees recognize and completely analyze all potential accident

sequences at their facilities. To this end, fuel cycle licensees typically require that criticality

safety staff review procedures associated with movement of fissile material, including

radiological control procedures.

The failure to review in-plant transport procedures and radiological controls can lead to the

creation of an unanticipated accident sequence. NRC criticality safety inspections typically

include review of the licensee criticality safety audit program, to ensure that analytical

assumptions are regularly reviewed in all areas. NRC criticality safety inspections routinely

review licensee facility operations to ensure that credible accident sequences have been

identified, analyzed, and controlled.

CONTACT

This information notice does not require any specific action or written response. Please direct

any questions about this matter to the technical contact below.

/RA/

Robert C. Pierson, Director

Division of Fuel Cycle Safety

and Safeguards

Office of Nuclear Material Safety

and Safeguards

Dennis Morey, NMSS

301-492-3112 E-mail: dcm@nrc.gov

Enclosure:

List of Recently Issued FSME/NMSS Generic Communications

ML072500291 OFC FSCC/TSB Tech ED FSME FCSS/TSB FCSS FCSS

NAME DMorey Ekraus: fax AMcIntosh DJackson JGiitter RPierson

DATE 9/ 7 /07 9/ 6 /07 9/ 7 /07 9/ 11 /07 9/ 11 /07 9/ 13 /07 OFFICIAL RECORD COPY Recently Issued FSME/NMSS Generic Communications

Date GC No. Subject

Addressees

02/02/07 IN-07-03 Reportable Medical Events Involving All U.S. Nuclear Regulatory Commission

Patients Receiving Dosages of medical use licensees and NRC Master

Sodium Iodide Iodine-131 less than Materials Licensees. All Agreement State

the Prescribed Dosage Because of Radiation Control Program Directors and

Capsules Remaining in Vials after State Liaison Officers.

Administration

02/28/07 IN-07-08 Potential Vulnerabilities of Time- All U. S. Nuclear Regulatory Commission

reliant Computer-based Systems licensees and all Agreement State

Due to Change in Daylight Saving Radiation Control Program Directors and

Time Dates State Liaison Officers.

03/13/07 IN-07-10 Yttrium-90 Theraspheres and All U.S. Nuclear Regulatory Commission

Sirspheres Impurities (NRC) Medical Licensees and NRC Master

Materials Licensees. All Agreement State

Radiation Control Program Directors and

State Liaison Officers.

04/04/07 IN-07-13 Use of As-Found Conditions to All licensees authorized to possess a

Evaluate Criticality-related Process critical mass of special nuclear material.

Upsets at Fuel Cycle Facilities

05/02/07 IN-07-16 Common Violations of the Increased All licensees who are implementing the

Controls Requirements and Related U.S. Nuclear Regulatory Commission

Guidance Documents (NRC) Order Imposing Increased Controls

(EA-05-090), issued November 14, 2005 and December 22, 2005.

05/21/07 IN-07-19 Fire Protection Equipment Recalls All holders of operating licenses for nuclear

and Counterfeit Notices power reactors and fuel cycle facilities;

except those licensees for reactors that

have permanently ceased operations and

who have certified that fuel has been

permanently removed from the reactor

vessel; and except those licensees for

decommissioned fuel cycle facilities.

06/11/07 IN-07-20 Use of Blank Ammunition All power reactors, Category I fuel cycle

facilities, independent spent fuel storage

installations, conversion facility, and

gaseous diffusion plants. Date GC No. Subject

Addressees

IN-07-23 Inadvertent Discharge of Halon All holders of operating licenses for nuclear

1301Fire-suppression System from power reactors, except those who have

Incorrect and/or Out-of-date permanently ended operations and have

Procedures certified that fuel has been permanently

removed from the reactor vessel. All

holders of licenses for fuel cycle facilities.

07/19/07 IN-07-25 Suggestions from the Advisory All U.S. Nuclear Regulatory Commission

Committee on the Medical Use of (NRC) medical-use licensees and NRC

Isotopes For Consideration to Master Materials Licensees. All Agreement

Improve Compliance With Sodium State Radiation Control Program Directors

Iodide I-131 Written Directive and State Liaison Officers.

Requirements in 10 CFR 35.40 and

Supervision Requirements in 10

CFR 35.27

08/13/07 IN-07-26 Combustibility of Epoxy Floor All holders of operating licenses for nuclear

Coatings at Commercial Nuclear power reactors and fuel cycle facilities

Power Plants except licensees for reactors that have

permanently ceased operations and who

have certified that fuel has been

permanently removed from the reactor

vessel.

03/01/07 RIS-07-03 Ionizing Radiation Warning Symbol All U.S. Nuclear Regulatory Commission

licensees and certificate holders. All

Radiation Control Program Directors and

State Liaison Officers

03/09/07 RIS-07-04 Personally Identifiable Information All holders of operating licenses for nuclear

Submitted to the U.S. Nuclear power reactors and holders of and

Regulatory Commission applicants for certificates for reactor

designs. All licensees, certificate holders, applicants, and other entities subject to

regulation by the U.S. Nuclear Regulatory

Commission (NRC) of the use of source, byproduct, and special nuclear material

03/20/07 RIS-07-05 Status and Plans for Implementation All NRC materials licensees, Radiation

of NRC Regulatory Authority for Control Program Directors, State Liaison

Certain Naturally-occurring and Officers, and NRCs Advisory Committee

Accelerator-produced Radioactive on the Medical Uses of Isotopes

Material

04/05/07 RIS-07-07 Clarification of Increased Controls All U.S. Nuclear Regulatory Commission

for Licensees That Possess (NRC) licensees issued NRCs Order

Collocated Radioactive Material Imposing Increased Controls and all

During Transportation Activities Radiation Control Program Directors and

State Liaison Officers Date GC No. Subject

Addressees

05/04/07 RIS-07-09 Examples of Recurring Requests for All holders of, and applicants for, a: (1) 10

Additional Information (RAIs) for 10 CFR Part 71 certificate of compliance

CFR Part 71 and 72 Applications (CoC) for a radioactive material

transportation package; (2) 10 CFR Part 72 CoC for a spent fuel storage cask; and (3)

10 CFR Part 72 specific license for an

independent spent fuel storage installation

(ISFSI).

06/27/07 RIS-06-27, Availability of NRC 313A Series of All U.S. Nuclear Regulatory Commission

Suppl. 1 Forms and Guidance for Their (NRC) medical-use licensees and NRC

Completion Master Materials licensees. All Radiation

Control Program Directors and State

Liaison Officers.

05/15/07 RIS-07-10 Subscriptions To New List Server

For Automatic Notifications Of All U.S. Nuclear Regulatory Commission

Medical-Related Generic (NRC) medical-use licensees and NRC

Communications, Federal Register Master Materials licensees. All Radiation

Notices And Newsletters Control Program Directors and State

Liaison Officers.

Note: A full listing of generic communications may be viewed at the NRC public website at the following address:

http://www.nrc.gov/Electronic Reading Room/Document Collections/Generic Communications