UNCERTAINTY AND SENSITIVITY ANALYSIS OF FOOD PATHWAY RESULTS WITH THEMACCS REACTOR ACCIDENT CONSEQUENCE MODEL

Uncertainty and sensitivity analysis techniques based on Latin hypercu be sampling, partial correlation analysis and stepwise regression anal ysis are used in an investigation with the MACCS model of the food pat hways associated with a severe accident at a nuclear power station. Th e primary purpose of this study is to provide guidance on the variable s to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident co nsequences. The effects of 87 imprecisely-known input variables on the following reactor accident consequences are studied: crop growing-sea son dose, crop long-term dose, milk growing-season dose, total food pa thways dose, total ingestion pathways dose, total long-term pathways d ose, area dependent cost, crop disposal cost, milk disposal cost, cond emnation area, crop disposal area and milk disposal area. When the pre dicted variables are considered collectively, the following input vari ables were found to be the dominant contributors to uncertainty: fract ion of cesium deposition on grain fields that is retained on plant sur faces and transferred directly to grain, maximum allowable ground conc entrations of Cs-137 and Sr-90 for production of crops, ground concent rations of Cs-134, Cs-137 and I-131 at which the disposal of milk will be initiated due to accidents that occur during the growing season, g round concentrations of Cs-134, I-131 and Sr-90 at which the disposal of crops will be initiated due to accidents that occur during the grow ing season, rate of depletion of Cs-137 and Sr-90 from the root zone, transfer of Sr-90 from soil to legumes, transfer of Cs-137 from soil t o pasture, transfer of cesium from animal feed to meat, and the transf er of cesium, iodine and strontium from animal feed to milk.