Irradiation of MEK - II: A detailed kinetic model for the degradation under of 2-butanone in aerated aqueous solutions steady-state gamma-radiolysis conditions

The radiolytic decomposition of aqueous phase 2-butanone (methyl ethyl keto ne (MEK)) has been studied extensively to gain a detailed mechanistic under standing of the effects of organic impurities on the behaviour of iodine in containment following a nuclear reactor accident. Based on the experimenta l results reported previously, a detailed reaction kinetic model for the st eady-state gamma-radiolysis of aerated aqueous solutions containing MER has been developed. The model consists of about 130 radiolytic decomposition r eactions in addition to about 25 water radiolysis reactions. The model repr oduces the observed dose profiles of MEK and its subsequent decomposition p roducts (3-hydroxy-2-butanone, acetaldehyde, acetic acid and formaldehyde) very well. The worst case was formaldehyde, a tertiary molecular product fr om MEK decomposition, which was still reproduced to within 50%. The model a lso reproduces the observed dose profile of pH reasonably well. The key rea ctions controlling the behaviour (or dose profiles) of MEK and its decompos ition products and the sensitivity of their behaviour to the rates of these reactions are discussed. Published by Elsevier Science Ltd.