Application of the Modular Risk Analysis Approach to the Hanford 200 Area Endstate Analysis. John W. Buck, Karl J. Castleton, and James L. Stroh, Pacific Northwest Laboratory, P.O. Box 999, MS K6-80, Richland, WA 99352
The modular risk analysis approach is being used to evaluate health impacts for the Hanford 200 Area endstate strategies. The modular risk analysis approach separates contaminant source inventory (source quantity [Q]), the contaminant release rate (unit flux factor series [UFFseries]), the environmental transport (unit transport factor Series [UTFseries]), the exposure assumptions (unit dose factor [UDF]), and health impacts (unit impact factor [UIF]) into components. These factors are used in the following relationship: Risk = Q x (UFFseries • UTFseries) x UDF x UIF. The UFFseries is the forcing function and the UTFseries is the response function of the system, which need to be convoluted as a series. The component definition can be conducted concurrently to reduce schedule time and the post-processing consists of simple combinations of the sources and unit factors. After the different components have been defined, any component can be modified without impact to the other components and the risk estimates can be quickly re-evaluated. This approach can be used for all major transport and exposure pathways. The objective of the Hanford 200 endstate strategy study is to evaluate the risk reduction potentials of different endstate options based on the strategy that all the retrievable waste be moved to the 200 Area or off-site. Various surface barriers, cement waste forms, and glass waste forms where considered for the onsite treatment and disposal. The modular risk analysis approach allows for different endstate strategies and options to be evaluated for a large installation and different waste types. The results can be used to assist in the difficult decision making process that needs to be made on radioactive and hazardous cleanup at the Hanford Site.
Pacific Northwest Laboratory is operated for the U.S. Department of Energy by Battelle Memorial Institute under Contract DE-AC06-76RLO 1830.