The present disclosure relates to nuclear chemical, particularly radiochemical, technologies at different stages of the nuclear fuel cycle, such as the production of purified nuclear materials (uranium, zirconium) or the reprocessing of spent nuclear fuel from nuclear power stations, in which extraction processes and operations for purifying nuclear materials are used. An example method, which includes the partial decomposition of nitric acid during continuous evaporation while a solution containing a reducing agent is fed into the bottom part of an evaporator having a circulating bottoms solution, consists in that the process is carried out such that the solution is kept in the bottom part of the evaporator for more than 2 hours under the addition of an aqueous solution of formaldehyde and formic acid (hereinafter “the mixture”) or a solution of formic acid after the process has been started using the mixture.

The invention relates to a method and an arrangement for operating a system in which dismantling works are performed underwater in a liquid-filled vessel (10) of a nuclear facility, the liquid being guided in a circuit (20) and flowing through at least one filter device (26, 28, 30). The liquid in the circuit flows through at least a first filter device (26) in the form of a coarse filter and a second filter device (28), in which at least one device from the group of ion exchangers (1, 2, 3), reverse osmosis systems, ultrafiltration systems, activated carbon filters, zeolite filters, and biological filters is used for filtration.

The invention relates to technology for processing liquid radioactive waste containing, inter alia, tritium isotopes, which are formed in various nuclear industry plants, and also during decommissioning of such plants. The technical result of the claimed invention consists in simplifying the technological procedure for processing liquid radioactive waste containing, inter alia, tritium isotopes by excluding complicated and lengthy operations associated with testing a concrete mixture produced from deactivated liquid radioactive waste, and also in increasing the ecological safety by reducing the size of areas for storage of the waste produced during the processing of the liquid radioactive waste. The claimed technical result is achieved in that a method for processing liquid radioactive waste containing, inter alia, tritium isotopes involves removing radioactive substances from the liquid radioactive waste so as to produce a low-level waste solution, and introducing a binder into the low-level waste solution produced in order to prepare a concrete mixture which complies with structural, radioecological, and sanitary and hygiene requirements, wherein components that have a negative effect on the technical characteristics of the concrete mixture being produced are removed from the low-level waste solution before the binder is added.

Disclosed herein is a nuclear power plant main steam system that reduces the atmospheric discharge of radioactive materials generated in an accident. The system includes: a decontamination water tank containing decontamination water; and a connection pipe for connecting the decontamination water tank to a main steam pipe which connects a steam generator and a turbine. A main steam safety valve or a connection valve is provided as a three-way valve configured to discharge the generated steam to the atmosphere when an accident occurs within a design basis and to transfer the generated steam to the decontamination water tank when an accident involving damage to nuclear fuel occurs. The main steam system reduces discharge of radioactive materials to the atmosphere when a containment bypass accident (e.g., a steam generator tube rupture caused by high-temperature steam) occurs.

A method for the anaerobic cultivation of microorganisms includes providing an aqueous solution having a pH value of 4.5 to 7.5 in a container, adding a substrate in a first substrate dosage to the aqueous solution, adding further elements to the aqueous solution, adding an inoculant with microorganisms to the aqueous solution, hermetically sealing the container, varying a temperature in a range from 40 to 80 degrees Celsius, taking a reference liquid sample and determining a first concentration of organic substance in the reference liquid sample, taking another liquid sample and determining another concentration of organic substance in the further liquid sample after the expiration of the first waiting time, if the further concentration of organic substance is smaller than 10 percent of the first concentration of organic substance, adding substrate in another substrate dosage, repeating until a sufficient amount of biomass is present in the container.

The present invention relates to a composition for transmuting a radioactive substance into a non-radioactive substance using complex microorganisms and a method for preparing the composition.

The present invention relates to a composition for transmuting a radioactive substance into a non-radioactive substance using complex microorganisms and a method for preparing the composition.

An exothermic transmutation method for at least partially deactivating radioactive material, the method comprising the steps of: —Arranging a dusty compound comprising at least a transition metal in a chamber (7) of a reactor (1) outside a closed container; —Arranging the radioactive material in said chamber (7), the radioactive material being and staying encapsulated in said closed container; —Providing hydrogen in contact with the dusty compound and with the radioactive material at a pressure higher than the ambient pressure; —Generating an electric field in the chamber (7), the electric field being applied to the dusty compound and the radioactive material; —Energizing the dusty compound by heating, then generating a transmutation of said at least one transition metal into another transition metal and proton emission towards the radioactive material, said radioactive material being at least partially deactivated, —Removing thermal energy from the reactor (1).

The present invention relates to a process for treating aqueous effluents from the primary circuit of a nuclear power plant implementing a separation of boric acid using a reverse osmosis membrane, characterized by the fact that it comprises steps consisting of treating the effluents using a multi-stage assembly composed of reverse osmosis modules comprising a membrane with a high boron rejection rate, arranged in parallel and in series, and recycling of the intermediate products to different points in the assembly.

Cleanup systems include plural coolant inputs that are physically combined to create a single flow at a desired filtering temperature. Filter(s) are used to clean the coolant, and coolant flowing therethrough will damage the filter or not be adequately filtered if having temperature in excess of an operating temperature of the filter. The inputs have different temperatures, and mixing them creates a combined flow at a desired temperature. The amount of each flow is selected based on its individual temperature to achieve this desired temperature. The combined flow is then conditioned with the filter at an operable temperature and returned to the coolant origin for the inputs. No heat exchangers or heat loss to outside heat sinks are required. Cleanup systems may be used with any coolant loop, including Rankine-cycle electricity generation systems like nuclear power plants, combustion boilers, and steam generators, and heat transfer systems.