Radioalysis and Stored Energy Release in a Mesitylene Moderator Chamber. Annex I

The safety problems associated with commonly used moderators such as hydrogen, deuterium, or methane are eliminated for the TCNS by using mesitylene as a moderator. Hydrogen, deuterium, and methane are gaseous at room temperature, and possible sudden temperature changes may lead to a dangerous pressure build-up in the moderator chamber. Mesitylene is a liquid at room temperature and is not explosive. It is a hydrogenous material with nuclear properties comparable to hydrogen. The radiolysis of mesitylene and stored energy in the moderator chamber and mesitylene have been evaluated. It was concluded that even in worst-case scenarios there would be no safety issue related to any damage to the reactor components and reactor core. Under all of the above evaluations, it is concluded that no credible accident involving the TCNS could cause damage to either the reactor beam tube or reactor core nor cause releases of radioactivity in excess of the limits prescribed by 10 CFR 20.