Technology, Safety and Costs of Decommissioning a Reference Low-Level Waste Burial Ground Environmental Surveillance Programs
This Addendum supplements, and to some extent replaces, the preliminary description of environmental radiological surveillance programs for low-level waste burial grounds (LLWBG) used in the parent document, 11 Technology, Safety and Costs of DecolliTlissioning a Reference Low-Level Waste Burial Ground, 11 NUREG/ CR-0570. The Addendum provides additional detail and rationale for the environmental radiological surveillance programs for the two referenced sites and inventories described in NUREG/CR-0570. The rationale and performance criteria herein are expected to be useful in providing guidance for determining the acceptability of environmental surveillance programs for other inventories and other LLWBG sites. Two generic burial grounds, one located on an arid western site and the other located on a humid eastern site, are reference facilities considered in this Addendum, and as described in the parent document (NUREG/CR-0570). The two sites are assumed to have the same capacity for waste, the same radioactive waste inventory, and similar trench characteristics and operating procedures. The climate, geology, and hydrology of the two reference sites are typical of existing western and eastern sites, altnough a single population distribution was chosen for both. Each reference burial ground occupies about 70 hectares and includes 180 trenches filled with a total of 1.5 x 10{sup 6} m{sup 3} of radioactive waste. In acldition, there are 10 slit trenches containing about 1.5 x 10{sup 3} m{sup 3} of high beta-gamma activity waste. In this Addendum environmental surveillance programs are described for the several periods in the life of a LLWBG: preoperational (prior to nuclear waste receipt); operational (including interim trench closures); post-operational (after all nuclear waste is received), for both short-term {up to three years) and long-term (up to 100 years) storage and custodial care; and decommissioning (only for the special case of waste removal). The specific environmental monitoring requirements for final site characterization and certification surveys are beyond the scope of this Addendum. Data collection associated with site reconnaissance and preselection is not specifically addressed, but it is recognized that such data may be useful in designing the preoperational program. Predisposal control measures, quality assurance, and record-keeping (other than inventory records) associated with waste disposal operations are also not addressed. The primary intent of routine environmental surveillance at a LLWBG is to help ensure that site activities do not cause significant transport of radioactivity from the site, resulting in an unacceptable health hazard to people. Preoperational environmental surveillance serves to determine for later comparison the background radioactivity levels, either naturally occurring or the result of man's activities (e.g. world-wide fallout or an adjacent nuclear facility), in and around the proposed burial ground site. The operational environmental surveillance program is used to estimate radiological conditions, both onsite and offsite as a possible result of burial ground activities, including trench closure(s). These data help to determine LLWBG compliance with regulatory requirements. During the post-operational period environmental surveillance should normally be an extension of the program carried out during operations, with appropriate deletions (or modifications) to account for the differences between operational and post-operational activities at the site. During the long-term storage and custodial care period, environmental surveillance serves to verify the radionuclide confinement capability of the burial ground and to identify problem situations requiring remedial action. For waste removal (exhumation), the environmental surveillance program is again modified to account for the greatly increased potential for direct radiation and contamination spread. At the time of decommissioning, "environmental surveillance" takes on a new meaning, from that of an ongoing program to one of site "characterization" and dose assessment, requiring more rigorous statistical design and testing than described for the other surveillance periods at a LLWBG. The environmental surveillance programs suggested in this Addendum are based on the radionuclide inventories given in Section 7 of NUREG/CR-0570 and the potential critical pathways determined for the reference sites. The Addendum suggests the use of exposure pathway analysis to evaluate the potential critical pathways to man from radionuclides in the waste. Hence, the monitoring programs recommended for the two reference sites include those nuclide/media resulting in the highest potential radiation dose or those in which the greatest buildup of contaminants can be expected. Appropriate use is made of existing regulations and other published reports and guides on the subject of environmental surveillance.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- Office of Nuclear Regulatory Research
- DOE Contract Number:
- DE-AC06-76RL01830
- OSTI ID:
- 1080053
- Report Number(s):
- PNL-3643; NUREG/CR-0570
- Country of Publication:
- United States
- Language:
- English
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