Shielded Payload Containers Will Enhance the Safety and Efficiency of the DOE's Remote Handled Transuranic Waste Disposal Operations

摘要

The Waste Isolation Pilot Plant (WIPP) disposal operation currently employs two different disposal methods: one for Contact Handled (CH) waste and another for Remote Handled (RH) waste. CH waste is emplaced in a variety of payload container configurations on the floor of each disposal room. In contrast, RH waste is packaged into a single type of canister and emplaced in pre-drilled holes in the walls of disposal rooms. Emplacement of the RH waste in the walls must proceed in advance of CH waste emplacement. This poses a significant logistical constraint on waste handling operations by requiring significant coordination between waste characterization and preparations for shipping among the various generators.To improve operational efficiency, the Department of Energy (DOE) is proposing a new waste emplacement process for certain RH waste streams that can be safely managed in shielded containers. RH waste with relatively low gamma-emitting activity would be packaged in lead-lined containers, shipped to WIPP in existing certified transportation packages for CH waste, and emplaced in WIPP among the stacks of CH waste containers on the floor of a disposal room. RH waste with high gamma-emitting activity would continue to be emplaced in the boreholes along the walls. The new RH container appears essentially the same as a nominal 208-liter drum, but is built with about 2.5 cm of lead, sandwiched between thick steel sheet. The top and bottom are made of very thick plate steel, for strengthening the package to meet transportation requirements, and provide similar gamma attenuation. This robust configuration provides an overpack for waste that otherwise would be remotely handled. Up to a 3:1 reduction in number of shipments is projected if RH waste were transported in the proposed shielded containers.This paper describes the container design and testing, as well as the regulatory approach used to meet the requirements that apply to WIPP and its associated transportation system. This paper describes the RH transuranic waste inventory that may be candidates for packaging and emplacement in shielded containers. DOE does not propose to use shielded containers to increase the amount of RH waste allowed at WIPP. DOE's approach to gain approval for the transportation of shielded containers and to secure regulatory approval for use of shielded containers from WIPP regulators is discussed. Finally, the paper describes how DOE proposes to count the waste packaged into shielded containers against the RH waste inventory and how this will comply with the volume and radioactivity limitations imposed in the many and sometimes overlapping regulations that apply to WIPP.