A method of decontaminating radionuclide-contaminated acid insoluble corrosion products from primary system surfaces in pressurized water reactors by oxidation and subsequent dissolution in an acidic decontamination solution of the corrosion products which have been made acid-soluble by the oxidation. The characterizing feature of the method is that the oxidation is carried out with a water-based oxidation agent having a pH below 7 and containing permanganate, chromic acid and ozone. In accordance with a preferred embodiment of the method the oxidation is carried out at relatively low temperature, e.g. under about 60oC and often below about 25oC.

Decontamination of pressurized water reactors

26 50,314 ABSTRACT OF THE DISCLOSURE This invention relates to an electric arc heater process and apparatus for the essentially complete decom-position of hazardous materials including polychlorinated biphenyls. Finely divided liquid or gaseous hazardous material is injected into a primary gas stream which has been superheated in an electric arc heater. The mixture is directed into a primary reactor for complete decomposi-tion with dwell times in the reactor being in the order of 0.05 to 0.15 seconds. The decomposition products are neutralized with the gases being released to atmosphare and any remaining particulates being collected for ultimate disposal. Large solid hazardous material is first shredded then heated in a roaster or rotary kiln to vaporize the primary gas stream. A soaking reactor is provided where increased dwell times are required for the decomposition of thermally stable compounds which may be formed in the primary reactor. When these compounds are absent the soaking reactor can be by-passed.

Electric arc heater process and apparatus for the decomposition of hazardous materials

A metal etching process involving an oxidation-reduction reaction where the metal being etched is oxidized and the active ingredient in the etchant solution is reduced, incorporates contacting said metal with an etching solution containing an active ingredient selected from the group consisting of ferric ions, ferricyanide ions, ceric ions, chromate ions, dichromate ions, and iodine, and introducing ozone into said etching solution to rejuvenate and agitate the solution.

Metal etching process with etch rate enhancement

A method for decontaminating metal surfaces having radioactive oxide deposits thereon is disclosed which comprises preparing a decontamination solution having a pH of about 1.5 to about 4 comprising water, about 0.02 to about 0.5% of a water soluble organic acid which has an equilibrium constant in a complex with ferric ion of at least about 109 and which is capable of producing a pH of about 2 to about 3 in water, and about 0.01 to about 0.4% of a chelate in free acid form which has an equilibrium constant in a complex with ferric ion of about 1015 to about 1019 and which is at least 0.4% soluble at 40° C. in water having a pH of about 2 to about 3. An apparatus for performing the above method is disclosed.

Decontamination of metal surfaces in nuclear power reactors

Ozone gas having a high ozone concentration is generated by a solid electrolyte electrolytic process. An ozone solution is prepared by injecting the ozone gas into an acidic solution of pH 6 or below. The ozone solution heated at a temperature in the range of 50° to 90° C. is supplied to a contaminated object to oxidize and dissolve a chromium oxide film by an oxidizing dissolving process. The ozone solution used in the oxidizing dissolving process is irradiated with ultraviolet rays to decompose ozone contained in the ozone solution, the ozone solution is passed through an ion-exchange resin to remove ions contained in the ozone solution. An oxalic acid solution is supplied to the contaminated object to dissolve an iron oxide film by a reductive dissolving process. Oxalic acid remaining in the oxalic acid solution after the reductive dissolving process is decomposed by injecting ozone into the oxalic acid solution and irradiating the oxalic acid solution with ultraviolet rays, and ions contained in the oxalic acid solution is removed by an ion-exchange resin.

Method of chemically decontaminating components of radioactive material handling facility and system for carrying out the same

Heat transfer and associated surfaces in nuclear reactors are decontaminated by treating the surface with ozone to oxidize acid-insoluble metal oxides to a more soluble state, removing oxidized solubilized metal oxides, and removing other surface oxides using low concentrations of decontaminating reagents. Ozone treatment has been found very effective with alloys having surface metal oxides rendered more easily dissolved by ozone oxidation especially with chromium or chromium-nickel containing alloys.

John Torok

Papers

Nuclear reactor decontamination

Dekontamination von kernreaktoren