Formation of Nitric and Organic Acids by the Irradiation of Ground Water in a Spent Fuel Repository

摘要

The formation of nitric acid has been reported in the literature, e.g. in connection with studies of glass leaching during irradiation. These experiments were carried out in order to evaluate the behaviour of glass as a matrix for highly radioactive waste. The presence of a nitrogen containing gas phase has been found to be important for the yield of the reaction. The formation of organic acids by radiolysis of carbonate solutions has been reported. The literature on the formation of organic and nitric acids have been surveyed and discussed. A conservative estimate of the formation of nitric and organic acids has been made based on dissolved nitrogen and carbonate in groundwater in a spent fuel repository. Outside a 10 cm thick copper canister containing spent fuel (the Swedish KBS-3 concept) the conservatively estimated total production of nitric, formic, and oxalic acids after 1 million years is 0.08 mol HNO sub 3 , 0.06 mol HCOOH, and 0.04 mol (COOH) sub 2 . For a thinner version of this canister with a wall thickness of only 1 cm, the conservatively estimated total production after 1 million years is 5 mol HNO sub 3 , 4 mol HCOOH, and 3 mol (COOH) sub 2 . (Atomindex citation 16:072460)