PROCESS FOR DECONTAMINATION OF METAL SURFACES IN A HEAVY-WATER COOLED AND MODERATED NUCLEAR REACTOR

The invention provides a method of decontaminating a metal surface in a heavy water cooled and moderated nuclear reactor, wherein the metal surface is coated with one or more metal oxides including radioisotopes, and wherein the metal surface is in contact with a heavy water coolant or moderator, the method comprising one or more treatment cycles each comprising an oxidation step wherein the metal surface is contacted with a solution of an oxidant in heavy water; a decontamination step wherein the metal surface subjected to the oxidation step is contacted with a decontamination reagent in heavy water for dissolving the one or more metal oxides and the radioisotopes in a decontamination solution and immobilizing the radioisotopes on an ion exchange resin; and a decomposition step wherein the decontamination reagent in the decontamination solution is decomposed; and wherein the oxidant, the decontamination reagent and the ion exchange resin are provided in a deuterated form and/or are free of active hydrogen. A heavy water nuclear reactor is adapted to perform the decontamination method.