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Risk Considerations ., . .~ . .~ ; This appendix presents examples of issues to be included in the kind of analysis proposed to determine the linkage between waste characteristics and risks in handling, transportation, and disposal of contact-handIed transuranic (CH-TRU) waste at the Waste Isolation Pilot Plant (WIPP). Constrained by both time and information, the committee could only point out some of the risks to be included in this risk analysis; a complete risk assessment is a major endeavor that the committee was not prepared to undertake. F.1 Risks Related to Waste Handling Risks to workers related to waste handling may arise in the recovery, characterization, and packaging of waste during operations at the generator sites; in transportation; and during receipt, temporary storage, and waste emplacement operations at WIPP. Worker exposures to the hazardous and radioactive constituents of the waste (through exposure to external radiation, inhalation, dermal contact, and ingestion) and industrial-type accidents are the main risk concerns. Hazardous material risks arise from potential exposures to hazardous metals (including beryllium, cadmium, lead, and mercury) and organic compounds, especially volatile organic compounds (VOCs). Generally, experience has shown that the more waste handling that is required to perform a given characterization activity, the greater the worker radiation doses. The collective worker dose has increased since WIPP opened and began to receive waste in 1999 because of the increase in number of shipments received. However, the collective dose to a population provides lithe specific information about individual dose Despite the increase in shipments and collective dose, the average annual worker dose has not varied significantly since ~999. Worker doses at WIPP have averaged only 1-2 mrem per year for all monitored workers; and no exposure has been reported for a majority of monitored workers. This is very low in comparison to the applicable permissible regulatory dose limit of 5,000 mrem per year, reflecting in part waste characterization being performed at the generator sites before shipment to WIPP. At the generator sites where the characterization is performed, worker doses are higher, but still well below the regulatory limits.4 Overall, doses to workers in normal operating conditions remain well below regulatory limits largely because DOE is taking appropriate measures to protect workers (see Appendix E). Public health risks from routine operations were estimated by considering exposure of members of the public living at the site boundary. Exposures have been so small that they have not been measurable in the presence of background radiation. Short-term operational risks in the proposed analytical framework would consider accident scenarios, such as fires, explosions, floods, or loss of containment Two case studies for worker radiation dose at generator sites are presented in Appendix E: the Savannah River Site and the Rocky Flats Environmental Technology Site. 116
Appendix F Risk Considerations 117 involving waste containing prohibited items (e.g., liquids) both at generator sites and at WIPP. F.2 Risks Related to Transportation Currently, CH-TRU waste is transported to WIPP from generator sites via highway in a TRUPACT-~! shipping containers. Studies have shown that radiation exposure to workers during transportation is well below regulatory limits under normal operating conditions (EEG, ~ 990; Neill and Neill, 2000~. Even in the most severe accident scenarios involving Type B transportation packages,2 loss of containment with release of radioactivity and exposure is considered unlikely (DOE-FSElS, ~ 997~.3 Occasional transportation accidents are inevitable because of the projected large number of shipments to WIPP. DOE estimates that over a 35-year period, WIPP will receive more than 37,000 shipments of TRU wastes from waste generator sites (DOE- FSElS, ~ 997~. Three minor transportation incidents involving WIPP shipments have already occurred since WIPP opened.4 In no case was the event serious, nor was there any release of radioactive material from the shipping container. To reduce the number of shipments, DOE is investigating the potential for requesting further modifications to the TRUPACT-~! Certificate of Compliance to increase the amount of waste in each shipment. Although DOE has not yet made a formal submission to the U.S. Nuclear Regulatory Commission (USNRC), there has been substantial interaction between the staffs in considering the risk of the 5 percent hydrogen generation limit to the health and safely of workers involved in the repackaging of waste Transportation risks are often at the heart of stakeholders' concerns at generator sites, in New Mexico, and in corridor states (see Section 4.6.4~. These concerns revolve primarily around accident consequences, and include concerns that, if waste is characterized using non-certified procedures, it has the potential to be out-of- compliance. Transportation risks to be addressed in these cases include the probability and consequences of transporting waste containing prohibited items, such as liquids. Also to be considered is the increased transportation risk from returning a shipment to a generator site because it is found to be out of compliance.5 i F.3 Risks Related to Waste Disposal Short-term operational risks at WIPP are discussed in Section Fat. ·ong-term risks related to waste disposal include operational risks if waste retrieval is necessary (e.g., waste "mining" accidents) and risks if the repository is breached (e.g., release of radioactivity into the environment). 2For a definition of Type B transportation package, see the Glossary. 3Although DOE never specified the probability of an accident with a release of radioactivity, DOE estimated a total of 0.4 latent cancer fatalities and 850 person-rem from "severe" transportation accidents (DOE-FSEIS, 1997~. 41n November 2000, a TRUPACT-II truck drove down a non-authorized road for about 27 miles before it was stopped by the state Police and re-directed to WIPP. In August 2002, a privately-owned vehicle hit a TRUPACT-II truck. Radioactivity contamination was found inside the inner containment vessel of the TRUPACT-II but it is unclear whether it was related to the accident. In any event, no radioactive release to the environment was detected. In September 2002, a TRUPACT-II truck driver lost consciousness causing the truck to cross the interstate median and end in a level field (DOE-CBFO, 2003~. 5Such a scenario occurred in August 2002. A TRUPACT-II truck upon inspection at WIPP was returned to the Idaho Engineering and Environmental Laboratory because radioactive contamination was detected in the inner vessel of the shipping container (DOE-CBFO, 2003~.
118 . . Improving the Characterization Program for Contact-Handled Transuranic Waste References EEG (Environmental Evaluation Group). 1 990. Risk Analysis of the Transport of Contact Handled Transuranic (CH-TRU) Wastes to WIPP along Selected Highway Routes in New Mexico Using RADTRAN IV. A. F. Gallegos and J. K. ChannelI. EEG-46. Albuquerque, N. Mex. Available at: <htip://www.eeg.org>. Neill, H. R., and R. H. Neill. 2000. Transportation of Transuranic Nuclear Waste to WIPP: A Reconsideration of Truck Versus Rail for Two Sites. Natural Resources Journals Volume 40~1 ):93-1 24. DOE-FSElS (DOE-Final Supplemental Environmental Impact Statement). 1997. Waste ~ solation Pi f of Plant Disposal Phase Final Supplemental Environ mental ~ mpact Statement. September. DOE/ElS-0026-S-2. CarIsbad, N.Mex. DOE-CBFO. 2003. WIPP Trucks Involved in Two Mishaps. TRU Progess Online. Available at: <http://www.wipp.carisbad. nm.us/pr/truprog/TRU_Progress_On~ine. htm>.
