The cost-benefit analysis of the remedial actions for the contaminated Enisey River floodplain, due to the release of radioactive materials at Mining Chemical Combine (MCC) «Krasnoyarsk-26» is carried out. The analysis was carried out for a region within the first 260 km below discharge point, where the Exposure Dose Rate (EDR) in the air ranges between 50 and 400 microR/hr and the concentration of the radionuclide reaches 25,000 Bq/kg. Both the methods of a) a cost-benefit analysis as functions of time and b) a cost justification analysis in the terms of the Action Levels (AL) have been used.
Two possible situations have been considered concerning the remediation of various sites on the contaminated floodplain:
1. The spatial and depth distribution of radioactive contamination is known. In this case, it is possible to estimate the cost of removing the contaminated soil as one of the alternatives of remediation. Two contrasting examples are analyzed, which cover the entire spectrum of possibilities for removal of the contaminated soil: a) The “Gorodskoy” Island, situated inside the “Eniseysk” City, at a distance of 260 km from MCC and b) the Islands and coast of the «Kazachenskoe» settlement, at a distance 160 km from MCC, where the impacted area, the volume of contaminated soil to be removed and the number persons impacted differ by an order of magnitude. These situations were analyzed as a cost-benefit in functions of time.
2. The information is limited: only the EDR or surface contamination is known. In this case, remediation by removing the contaminated soil is impossible. In this case, remedial actions result only in limiting the people’s actions (i.e. - closure of the area). This is a typical and frequent occurrence concerning remedial actions for the Enisey River floodplain. These situations were analyzed as “generic”: the doses were analyzed using data concerning surface contamination and resulted in pessimistic estimations of the site’s specific parameters, the level of contamination and information about depth profiles of the radionuclide-specific concentration in the soil of the Enisey River floodplain. Cost justification of closure of the area is analyzed in terms of the AL.
Cost-benefit as functions time and analysis in terms of the AL were used to analyze the alternatives of remedial actions: a) no action, b) removal of the contaminated soil without its stabilization, c) stabilization by the injection of silicate of sodium into the soil, followed by the excavation and removal of the firm soil, d) closure of the area. The cost used, in accordance with the cost assigned to the unit collective dose a (alpha)= $20,000–$3,000 per man*Sv, facilitates a comparison of the justification of the cost alternatives of remedial action to suit the different economical conditions in Russia (the numeral values a were chosen by experts of MCC).
It has been proven that under current Russian economical conditions (α = $3,000 per man*Sv) “no action” is best for most contaminated sites on the Enisey River floodplain. Removal of contaminated soil (without stabilization) is cost justified action for high contamination of small areas (such as “Gorodskoy” Island) only. Removal of the contamination in large areas (such as the “Kazachenskoe” settlement) may be a cost justified action in the future (for α = $20,000 per man*Sv).