Information Notice 2002-03, Highly Radioactive Particle Control Problems During Spent Fuel Pool Cleanout
| ML011790547 | |
| Person / Time | |
|---|---|
| Issue date: | 01/10/2002 |
| Revision: | 0 |
| From: | Beckner W D Operational Experience and Non-Power Reactors Branch |
| To: | |
| References | |
| TAC MB1382 IN-02-003 | |
| Download: ML011790547 (7) | |
January 10, 2002
NRC INFORMATION NOTICE 2002-03:HIGHLY RADIOACTIVE PARTICLE CONTROLPROBLEMS DURING SPENT FUEL POOL CLEANOUT
Addressees
All holders of operating licenses for nuclear power reactors, holders of licenses for permanentlyshutdown facilities with fuel onsite, and holders of licenses for non-power reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alertaddressees to recent issues involving evaluation and control of radioactive particles generated during removal of material from a spent fuel pool prior to shipping the material offsite for disposa The issue emphasized in this notice is that highly radioactive (hot) particles represent a radiological hazard not just in terms of shallow dose to the skin or an extremity but also as a deep or whole-body dos It is expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problem However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is require
Description of Circumstances
Toward the end of a 5-month spent fuel pool cleaning project, the Susquehanna Steam ElectricStation completed compacting irradiated components that had been temporarily stored in the poo Working under water remotely, the licensee had used an "advanced crusher and shearer" (ACS) unit to compact control rod blades and local power range monitor On October 12, 2000, the ACS was removed from the cask storage pit with a crane after apparently inadequate cleaning with a high-pressure spray Hydrolaze The ACS was moved over the refueling floor and into the reactor head washdown area for further decontamination prior to shipment offsit The ACS was not totally wrapped or sealed during this movemen Also, access to the ACS pathway over the refueling floor was not radiologically controlled during the move. During the movement of the ACS, the refueling floor local area radiation monitor began toalar The cause was a previously unidentified highly radioactive particle which had fallen from the AC The particle was later determined to be a 2.78 gigabecquerel (Gbq) [75 millicuries (mCi)] Co-60 particle, reading approximately 8 sievert/h (Sv/h) (800 rem/h) at contact. The licensee stopped work, shielded and captured the particle, and initiated radioactive particlecontrol zone coverage for the entire refueling floo Additional actions undertaken at that time included formation of a root cause event review tea The team's work led to upgraded controls, surveying, more management oversight and more detailed planning and work procedures for handling high specific activity particles.A search was then begun for additional hot particles on the refueling floo Workers in particlecontrol zones were surveyed for particles every 15 minutes, and more protective clothing (PC)
was required for certain work activitie The 15-minute control was a default stay time, and not based on dose calculations for the high-activity particles known to be present.During the cleanup activities, more than 30 radioactive particles were found on the refuelingfloo Two high activity radioactive particles found on September 9 and December 6, 2000, had resulted in shallow-dose equivalent (SDE) exposures of 0.12 and 0.17 Sv (12 and 17 rem),
which is below the annual SDE limit of 50 re The licensee discovered two more high-activity particles, a 0.78 Gbq (21 mCi) particle on November 28, and a 0.7 Gbq (19 mCi) particle on December 4, 2000; these particles did not result in significant exposure to personne No actual exposures in excess of any annual dose limits occurred during the cleanup activities.During a scheduled NRC health physics, rad-waste transportation, baseline inspection duringDecember 11-15, 2000 (Inspection Report Nos. 05000387/2000-009 and 05000388/2000-009, ADAMS Accession No. ML010250469), the NRC inspector identified significant weaknesses in the licensee's particle control progra The inspector noted that the licensee had failed to identify that conventional hand-held survey instruments using standard survey methods were underestimating the contact dose rates of the particles, thus underestimating the radiological hazards not just to the skin but in terms of whole body exposure. The licensee's evaluation had failed to consider properly and account for the potential forsubstantial dose to personnel from the high-activity particle Specifically, the 15-minute worker stay time was not adequate to prevent potential overexposures from the particles known to be present in and around the refueling floo The stay time would have allowed both SDE and total effective dose equivalent (TEDE) annual exposure limits to be exceeded.Four of the particles found ranged from to 2.78 Gbq (19 to 75 mCi). Had the particles beendirectly on the workers' PCs, the TEDE annual limit of 0.05 Sv (5 rem) could have been exceeded in 25 seconds to 2 minutes, and the SDE limit exceeded in 6 to 21 seconds, depending on the activity of the individual particle.In response to the NRC findings and a 0.17 Sv (17 rem) SDE exposure on December 6 from aparticle on a worker's boot, licensee management stopped all high-risk work, initiated a comprehensive events evaluation, requested on-site assistance by an industry expert team, and implemented improved training and communication of lessons learned in this are DiscussionDuring previous similar processing of irradiated components at Susquehanna in 1991,radioactive particles had been identified with external gamma dose rates greater than 100 rem/h However, the plant failed to incorporate fully this previous experience and industry- wide experience into the planning for the 2000 fuel pool clean out projec (NRC Information Notice No. 90-33, "Sources of Unexpected Occupational Radiation Exposures at Spent Fuel Storage Pools," also concerns highly radioactive particles.)Prior to the NRC baseline inspection, after the initial event, the work controls that the licenseehad implemented were not sufficient under the circumstances to evaluate and control the potential radiological challenges posed by these extremely high activity particle A Notice of Violation (failure to conduct adequate evaluation and survey) associated with a White finding (using the Significance Determination Process) was issue These actions were taken because of the substantial potential for exposure in excess of the annual limit for TEDE even though no worker dose limits were exceeded.During the regulatory conference for this violation, the licensee stated that it needed to improveits hot particle surveying, identification, handling, and contro The improvements included more effective use of remote handling techniques, proactive staging of particle control zones, and aggressive treatment of potential sources of particles by using decontamination and filtration on systems that communicate with the spent fuel pool.The licensee noted that in cases like this where a contractor was used for a challengingradiological evolution, plant management oversight was essentia That oversight must focus on, and have sufficient resources to implement and maintain a sense of an acceptable radiation culture and acceptable practices and standards for radiation wor According to the licensee, this can best be accomplished by direct ownership for significant, high-risk projects demonstrated by the visible presence and direct oversight of the work by utility managers.Most importantly, this occurrence demonstrated a need to strengthen procedural controls tofocus attention on the large potential doses from these challenging radiological work environment The worker training program and job oversight must emphasize the most important lesson learned from the event-that radioactive particles can present not only shallow-dose risks but, at higher activity levels, whole body dose risks, which can be much more significan This information notice requires no specific action or written respons If you have anyquestions about the information in this notice, please contact one of the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Program Director Operating Reactor Improvements Program Division of Regulatory Improvement Programs Office of Nuclear Reactor RegulationTechnical contacts: James E. Wigginton, NRRJames D. Noggle, Region I301-415-1059610-337-5063 E-mail: jew2@nrc.govE-mail: jdn@nrc.gov
Attachment:
List of Recently Issued NRC Information Notices This information notice requires no specific action or written respons If you have anyquestions about the information in this notice, please contact one of the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager./RA/William D. Beckner, Program Director Operating Reactor Improvements Program Division of Regulatory Improvement Programs Office of Nuclear Reactor RegulationTechnical contacts: James E. Wigginton, NRRJames D. Noggle, Region I301-415-1059610-337-5063 E-mail: jew2@nrc.govE-mail: jdn@nrc.gov
Attachment:
List of Recently Issued NRC Information NoticesDistribution:PUBLIC IN FileADAMS ACCESSION NUMBER: ML011790547*See previous concurrenceOFFICEREXBTech EdIOLBSC:REXBRORPNAMEEGoodwin*PKleene*GTracy*JTappert*Wbeckner*DATE12/20/20016/19/20018/20/20016/26/200101/08/2002OFFICIAL RECORD COPY
______________________________________________________________________________________OL = Operating License CP = Construction PermitAttachment 1 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICES_____________________________________________________________________________________InformationDate of Notice N SubjectIssuanceIssued to_____________________________________________________________________________________2002-02Recent Experience withPlugged Steam Generator Tubes01/08/2002All holders of operating licensesfor pressurized-water reactors (PWRs), except those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor.2002-01Metalclad Switchgear Failuresand Consequent Losses of Offsite Power01/08/2002All holders of licenses for nuclearpower reactors.2001-19Improper Maintenance andReassembly of Automatic Oil Bubblers12/17/2001All holders of operating licensesfor nuclear power reactors, except those who have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.2001-18Degraded or Failed AutomatedElectronic Monitoring, Control, Alarming, Response, and Communications Needed for Safety and/or Safeguards12/14/2001All uranium fuel conversion,enrichment, and fabrication licensees and certificate holders authorized to receive safeguards informatio Information notice is not available to the public because it contains safeguards information.2001-17Degraded and FailedPerformance of Essential Utilities Needed for Safety and Safeguards12/14/2001All uranium fuel conversion,enrichment, and fabrication licensees and certificate holders authorized to receive safeguards informatio Information notice is not available to the public because it contains safeguards information.2001-08,Sup. 2Update on Radiation TherapyOverexposures in Panama11/20/2001All medical licensees.2001-16Recent Foreign and DomesticExperience with Degradation ofsteamGeneratorTubes and Internals