Electrolytic decontamination process and process for reproducing decontaminating electrolyte by electrodeposition and apparatuses therefore

A process for two step electrolytic decontamination of a radioactivity contaminated metal surface of an object, comprising the steps of removing the radioactivity from said radioactively contaminated metal surface by mounting the object as an anode in a first cell, using a diluted electrolyte that is relatively easy in waste disposal, and then mounting the object as an anode in a second cell for electrolytically polishing the surface by using an electrolyte that is effective in providing a relative luster on the metal surface.

A process for the reproduction of high concentration acid decontaminating electrolyte having been used, and whose service life is over, in an electrolytic decontamination of a radioactively contaminated object, said process comprising the steps of utilizing a reproduction cell which is divided by a diaphragm into an anode chamber and a cathode chamber of equal capacity, providing an insoluble electrode in said anode chamber and a capture electrode in said cathode chamber, supplying said anode chamber with electrically conductive initial electrolyte whose hydrogen ion concentration is adjusted to about pH 2 by the addition of an acid solution of the same components as said decontaminating electrolyte, supplying said cathode chamber with a spent electrolyte and supplying DC current through said diaphragm between said insoluble electrode and said capture electrode whereby, during operation, as the acid ions move into the anode chamber through the diaphragm, the metallic ions in the spent electrolyte are removed by deposition on said capture electrode in the cathode chamber, and the acid concentration of the electrolyte in said anode chamber is increased up to said initial electrolyte for reuse as a substantially metal-free high concentration electrolyte.

A process for the reproduction of a decontaminating electrolyte of high concentration phosphoric acid series used for electrolytic decontamination of radioactively contaminated objects, utilizing extraction ad inverse extraction of phosphoric acid before feeding the decontaminating electrolyte into a reproducing cell, said process comprising the steps of extracting phosphoric acid from the decontaminating electrolyte using a solvent, injecting the extracted electrolyte into a cathode chamber of an electrodeposition reproducing cell, inversely extracting a phosphoric acid from said solvent by water for use as an initial electrolyte, injecting the inverse extracted solution into an anode chamber of the reproducing cell, said reproducing cell being divided by a diaphragm into an anode chamber having an insoluble electrode, and a cathode chamber having a capture electrode, supplying DC current through the diaphragm between the insoluble electrode and the capture electrode in said reproducing cell, thereby capturing metallic ions by electrodeposition in said cathode chamber as well as increasing Phosphoric acid concentration of the solution in the anode chamber upto that of the initial electrolyte to be reused as a decontaminating electrolyte.

Apparatus for electrolytic decontamination of a metal object having a radioactively contaminated metal surface, comprising an electrolytic decontaminating first cell, the object to be decontaminated and one or more electrodes being dipped in an electrolyte of said first cell, a positive DC potential and a negative DC potential being connected to said object and electrodes so that they respectively operate as an anode and a cathode when DC current is passed between said object and electrodes to electrolytically polish the metal surface of the object, a separate metallic ion isolating second cell being partitioned by a diaphragm into an anode chamber having an insoluble electrode and a cathode chamber having a capture electrode, means for circulating a decontaminating electrolyte between said first cell and said anode chamber of said second cell, and means for injecting the electrolyte from the anode chamber of said second cell into said cathode chamber of said second cell to maintain hydrogen ion concentration therein to such an extent as to isolate metallic ions by deposition on the capture electrode, and acid ions therein to move into the circulating electrolyte in the anode chamber through the diaphragm during the DC current flow.

Apparatus for the reproduction of spent electrolyte of a high concentration acid solution having been used in electrolytic decontamination of a radioactively contaminated object, said apparatus comprising a reproducing cell being partitioned by a diaphragm into an anode chamber and a cathode chamber of equal capacity, said anode chamber being initially filled with an initial electrolyte formed by an electrically conductive aqueous solution whose hydrogen ion concentration is adjusted to substantially pH 2, means for injecting a spent electrolyte into said cathode chamber from an electrolyte decontamination cell, an insoluble electrode being dipped in said solution of the anode chamber, and a capture electrode being dipped in the spent electrolyte of the cathode chamber, means for injecting the solution from said anode chamber into said cathode chamber, and means for supplying DC current through the diaphargm between said insoluble electrode and said capture electrode, whereby, as the acid ions of the spent electrolyte move into the cathode chamber through the diaphragm, radioactive ions in the cathode chamber are removed by electrodeposition on the capture electrode, and acid concentration in the anode chamber is increased up to that of the initial electrolyte to be reused in the electrolytic decontamination.

Apparatus for reproduction of decontaminating electrolyte of high concentration phosphoric acid series being used for electrolytic decontamination of radioactively contaminated objects, utilizing extraction and inverse extraction of phosphoric acid, said apparatus comprising an electrodeposition reproducing cell being divided by a diaphragm into an anode chamber having an insoluble electrode, and a cathode chamber having a cathode electrode, means for extracting phosphoric acid from a radioactive decontaminating electrolyte using a solvent, means for inversely extracting phosphoric acid from said solvent by water, means for injecting the extractive phosphoric acid solution into said cathode chamber, and inversely extracted phosphoric acid solution into said anode chamber of the reproducing cell, said inversely extracted phosphoric acid solution forming an initial electrolyte, and means for supplying DC current between a capture electrode of the reproducing cell and said insoluble electrode, thereby removing metallic ions by electrodeposition on the capture electrode in said cathode chamber as well as increasing the phosphoric acid concentration of the solution in the anode chamber up to that of the initial electrolyte to be reused in the decontamination cell.