The patent discloses method and control system for gas injection into the coolant of a nuclear reactor plant. The method includes the following steps: gas to be injected into the coolant is supplied from the gas system to the above-coolant space; gas is injected into the gas system from the above-coolant space. Technical result: prevention of reuse of contaminated gas.

An insulated solution injector may include an outer tube and an inner tube arranged within the outer tube. The outer tube and the inner tube may define an annular space therebetween, and the inner tube may define a solution space within. The annular space may be configured so as to insulate the solution within the solution space. As a result, the solution may be kept to a temperature below its decomposition temperature prior to injection. Accordingly, the decomposition of the solution and the resulting deposition of its constituents within the solution space may be reduced or prevented, thereby decreasing or precluding the occurrence of a blockage.

Disclosed are an apparatus and a method for purifying Li.sup.7 ions from reactor coolant radioactive material and adjusting pH of the reactor coolant. The apparatus comprises a radioactive metal ion recovery unit comprising a first negative electrode member having a negative (?) electrode connected thereto and a first positive electrode member having a positive (+) electrode connected thereto, and an Li ion separation/concentration unit. The radioactive metal ion recovery unit is configured such that the reactor coolant discharged from the non-generative heat exchanger passes between the first negative electrode member and the first positive electrode member The Li ion separation/concentration unit comprises a second positive electrode member having a second positive (+) electrode connected to one side of the Li ion separation/concentration unit, a second negative electrode member having a negative (?) electrode connected to the other side of the Li ion separation/concentration unit, and a cation-exchange membrane provided between the second positive electrode member and the second negative electrode member and configured to pass a cation therethrough. The Li ion separation/concentration unit is configured such that the reactor coolant that passed through the radioactive metal ion recovery unit passes between the second positive electrode member and the cation-exchange membrane Accordingly, Li.sup.7 ions, produced in the reactor coolant and passed through the cation-exchange membrane, move toward the second negative electrode member and are separated. The apparatus further comprises an Li.sup.7 concentration tank configured to concentrate Li.sup.7 in a recycling process in which Li.sup.7 separated from the Li ion separation/concentration unit is recycled again to the Li ion separation/concentration unit.

A method for depositing divalent metal compounds on the surface of a nuclear power plant component, the component being a nickel-based or austenitic stainless steel alloy includes: providing within the component an aqueous treatment solution containing at least one soluble metal-containing compound such as a zinc salt and at least one source of oxygen; allowing the treatment solution to remain in the component until the compound is deposited on the wetted surface of the component; and, removing the aqueous solution after exposure. The treatment may be applied more than once, using more than one divalent metal compound, and the surface may further be exposed to a solution containing a noble metal species and a reducing agent. The treatment temperature is preferably below 100? C.

An aqueous solution of alkali hexahydroxo platinate is produced. As a alkali hexahydroxo platinate, sodium hexahydroxoplatinate or potassium hexahydroxoplatinate is used. The aqueous solution of alkali hexahydroxo platinate is passed through a hydrogen form cation exchange resin layer in a cation exchange resin tower. The aqueous solution of alkali hexahydroxo platinate makes contact with the hydrogen form cation exchange resin of the hydrogen form cation exchange resin layer, thus a suspension of hexahydroxo platinic is generated. If gamma rays are irradiated to the suspension, a platinum oxide colloidal solution in which colloidal particles including a platinum dioxide, a platinum monoxide, and a platinum hydroxide exist is generated. In a platinum oxide colloidal solution, the content of impurities is little and a noble metal compound is dispersed stably in water.

The present disclosure provides a method for relieving a corrosive environment of a boiling water reactor, the method including a step of injecting hydrogen and a noble metal compound into water to be replenished into the reactor pressure vessel during a period of a generating operation of a boiling water nuclear power plant including the reactor pressure vessel. In the method, the hydrogen is injected into water to be supplied into the reactor pressure vessel, and the noble metal compound is injected into water in a line of the boiling water nuclear power plant in which a concentration of oxygen or hydrogen peroxide is stoichiometrically higher than the concentration of hydrogen at which hydrogen undergoes a chemical reaction to turn to water. Thus, when a noble metal is injected into a boiling water reactor, the noble metal can be restrained from adhering onto a pipe for an injection and other pipes, and thereby can increase the amount of the noble metal to be injected into a cooling water in a reactor pressure vessel.

The present invention relates to a pre-core hot functional testing (HFT) preconditioning process, which includes the introduction of chemical additives, e.g., zinc, into coolant water that circulates through the primary system of a new nuclear power plant, at various temperatures. The chemical additives contact the primary system surfaces, which results in the formation of a protective zinc-containing oxide film on the fresh surfaces to control corrosion release and deposition during subsequent normal operation of the nuclear power plant. The method includes a series of three chemistry phases to optimize the passivation process: 1) an alkaline-reducing phase, 2) an acid-reducing phase and 3) an acid-oxidizing phase.

A nuclear reactor plant including a reactor; a coolant in the reactor; a gas system connected to the reactor and adapted to provide a gas supply to and gas removal from a space above the coolant; and a device for injection of gas into the coolant. The device is installed partially in the coolant and partially in the space above the coolant, and is adapted to supply gas from the space above the coolant to the coolant. The gas system and device are configured to carry out steps including: supplying gas to be injected into the coolant from the gas system to the space above the coolant space; injecting gas into the coolant by maintaining the gas pressure higher than coolant pressure in the device; and injecting gas into the gas system from the space above the coolant.

The invention relates to compositions and methods for coating a zirconium alloy cladding of a fuel element for a nuclear water reactor. The composition includes a master alloy including one or more alloying elements selected from chromium, silicon and aluminum, a chemical activator and an inert filler. The alloying element(s) is deposited or are co-deposited on the cladding using a pack cementation process. When the coated zirconium alloy cladding is exposed to and contacted with water in a nuclear reactor, a protective oxide layer can form on the coated surface of the cladding.

A method of decontaminating metal surfaces in a cooling system of a nuclear reactor comprises: an oxidation step, comprising at least one acidic oxidation step and at least one alkaline oxidation step wherein metal oxides and radioisotopes on the metal surfaces are contacted with aqueous permanganate oxidant solutions; followed by a decontamination step wherein an aqueous solution comprising oxalic acid, formic acid, citric acid, tartaric acid, picolinic acid, gluconic acid glyoxylic acid or mixtures thereof is used to dissolve at least part of the metal oxides and radioisotopes; and a cleaning step wherein radioisotopes are immobilized on an ion exchange resin; wherein at least one treatment cycle includes a high temperature oxidation step, wherein the permanganate oxidant solution is kept at a temperature of at least 100 C.