Westinghouse Electric Corporation

The United States of America As Represented by the United States

Alexander P Murray

Clifton G Slater

Thomas S Snyder

Francis R Spurrier

Egon A DeZubay

Robert W White

Edward J Vidt

Lawrence F Becker, Jr

Michael C Skriba

Sharon L Weisberg

Metal surfaces having an oxide coating containing radioactive substances, such as the primary system of a pressurized water reactor, are decontaminated by passage thereover of a decontamination solution containing a weak chelating agent, such as nitrilotriacetic acid, and a ferrous salt, such as ferrous glutonate. The weak chelating agent is present in an aqueous solution in an amount of 0.1 to 2.0 percent by weight and the ferrous salt in an amount to provide 50 to 500 parts per million iron based on the weight of the solution. The solution, after contact with the metal surfaces is regenerated by an ion exchange resin or, preferably, by electrolysis.

Method for decontaminating a pressurized water nuclear reactor system

Disclosed is a method of decontaminating the metal surfaces in the cooling system of a nuclear reactor by contacting the metal surfaces with an aqueous solution containing about 0.5 to about 3% of a ceric acid which can be tetrasulfato ceric acid, hexasulfamato ceric acid, hexaperchlorato ceric acid, or mixtures thereof, and about 1 to about 5% of an inorganic acid that forms a complex with the ceric acid. The cerium III in the aqueous solution can be oxidized to cerium IV to increase the life and effectiveness of the solution. After oxidation, the aqueous solution can be passed through a hydrogen form cation exchange column to remove metal ions. If the aqueous solution contains uranyl or plutonyl ions these can be recovered by extraction for use in making fuel. Also disclosed is a decontaminating solution of water containing about 0.5 to about 3% of a ceric acid which can be tetrasulfato ceric acid, hexasulfamato ceric acid, hexaperchlorato ceric acid, or mixtures thereof, and about 1 to about 5% of an inorganic acid that forms a complex with the ceric acid.

Ceric acid decontamination of nuclear reactors

Both a method and apparatus for electrolytically removing radioactive metal ions from a decontamination solution to regenerate the solution and prepare the ions for disposal as disclosed herein. At least the cathodic portion of the electrode used in the electrolysis is formed from a combustible material, such as a semi-fluidized bed of graphite particles. In the method of the invention, the decontamination solution is passed in intimate contact with the graphite particles forming the cathodic portion of the electrode as an electric potential is applied to the electrode. As a result of the electric potential, the metal ions are detached from the chelate in the decontamination solution and deposited onto the graphite particles of the cathodic portion of the electrode. After the electrode becomes spent, it is incinerated in order to reduce the volume of the resulting radioactive ash. The gases produced from the incineration are scrubbed with a scrubbing liquid to remove radioactive particles therefrom. The contaminated scrubbing liquid is in turn used to form a cementitious substance or grout which encapsulates the radioactive ash. The invention provides a more effective method of removing radioactive ions from decontamination solutions, and does not create any radioactive eluants. The resulting solid waste is of small volume.

Electrolytic decontamination apparatus and encapsulation process

Disclosed is a method of decontaminating metal surfaces contaminated with a radioactive deposit by passing over the coating an aqueous solution of a water soluble condensation reaction product of (1) a hydrazine compound having the general formula ##STR1## where each R group is independently selected from hydrogen and alkyl to C.sub.4 and (2) a water soluble aliphatic polycarboxylic acid. The method includes the additional last steps of passing an aqueous oxidizing solution over the deposit followed by passing a decontamination solution over the deposit a second time. The solution is circulated through a cationic exchange column which can be preloaded with hydrazine ion. The decontamination solution can be decomposed by the addition of an oxidant to form nitrogen, carbon dioxide, and water.

Method of decontaminating radioactive metal surfaces

Disclosed is an improved process for oxidizing chromium in deposits in the cooling system of a nuclear reactor using a solution of ozone. The improvement consists of adding to the solution about 0.01 to about 0.5% of a water-soluble cerium IV compound, about 0.1 to about 0.5% of a water-soluble aromatic compound having at least one ketone group on an aromatic ring, or adding both. Also disclosed is the composition of water, ozone, the cerium IV compound and the aromatic compound. Also disclosed is a process for decontaminating the cooling system of nuclear reactors by adding a decontamination composition to the coolant, circulating the coolant between the cooling system and a cation exchange resin, removing the decontamination composition by passing it through an anion exchange resin, adjusting the temperature to 40.degree. to about 100.degree. C., adding the ozone oxidation composition, circulating the coolant through the cooling system, raising the temperature to at least about 100.degree. C., passing the coolant through an anion exchange resin or a mixed resin, adjusting the temperature to about 60.degree. to 100.degree. C. and repeating the addition of the decontamination composition and its removal.

Ozone oxidation of deposits in cooling systems of nuclear reactors

Disclosed is an oxidizing composition of water, about 0.1 to saturation of an alkali metal hypohalite, and sufficient alkali metal hydroxide to raise the pH of the solution to at least about 12. A method of decontaminating metal surfaces having a coating thereon which contains radioactive substances is also disclosed. The composition is passed over the coating at a temperature of about 50.degree. to about 120.degree. C. followed by passing a decontamination solution over the coating.

Hypohalite oxidation in decontaminating nuclear reactors

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 10.sup.9 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 10.sup.15 to about 10.sup.19 and which is at least 0.4% soluble at 40.degree. 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

Disclosed is a method of decontaminating metal surfaces having a radioactive coating thereon where the coating contains metal ions. An aqueous decontamination solution containing at least one chelate is passed over the coating to solubilize the metals. The decontamination solution is then passed through a porous direct current electrode to reduce the metal ions in the solution and the decontamination solution is again passed over the coating. Also disclosed is an apparatus for decontaiminating metal surfaces coated with radioactive substances. The apparatus consists of a container means for holding an aqueous decontamination solution where the solution contains a chelate, a porous cathode through which the aqueous decontamination solution is passed, and means for circulating the aqueous decontamination solution between the container means, the porous cathode, and the metal surfaces.

Decontamination using electrolysis

Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot combustion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

Slab reformer

Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot comubstion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

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Murrysville, PA, United States of America

Alexander P Murray