RU2230379C2 - Heavy liquid-metal coolant decontaminating filter - Google Patents

Abstract

FIELD: decontaminating liquid-metal coolants. SUBSTANCE: filter has casing with filter element provided on top part of casing with pipe connections running to gas cylinders filled with reducing mixture and to steam condensers. Passing coolant through decontaminating filter provides for reducing amount of radioactive wastes discharged from NPS power units. EFFECT: enhanced efficiency and extended service life of filter. 1 cl, 2 dwg

Description

The solution relates to nuclear engineering and can be used in reactor plants and in experimental circuits with heavy liquid metal coolant (TZHMT).

Known cold flow-type trap containing a housing, a recuperative part (fridge coils), a stuffed filter made of stainless wire, and a sump (see Ganchev B.G., Kalishevsky L.L. et al. Nuclear power plants. - M. : Energoatomizdat, 1990, p. 540) - prototype.

The disadvantage of this technical solution in relation to nuclear power plants with a liquid metal coolant (LMT) is the need to cut it out of the loop and store it after accumulating and clogging the filter and then install a new filter, which is uneconomical and increases the amount of radioactive waste.

The task to be solved is to improve the design of the TZHMT purification filter, increase radiation safety and increase the efficiency of a nuclear power plant or an experimental circuit with TZHMT based on lead or its alloys.

The technical result is an increase in efficiency and an increase in the service life of the TZhMT cleaning filter without dismantling it or a filter element, and a decrease in the amount of radioactive waste from nuclear power units.

The technical result is achieved by the fact that the filter for cleaning TZHMT, comprising a housing with a filter element, is equipped in the upper part of the housing with nozzles connected to gas cylinders with a reducing mixture and to steam condensers.

Figure 1 presents a part of the contour of a nuclear power plant or experimental stand that implements the proposed technical solution; figure 2 - filter cleaning TZHMT.

The composition of the circuit includes a make-up tank 1 with a liquid metal base based on lead or its alloys, a cleaning filter TZHMT in the form of a housing 2 with a filter element 3. The reducing gas system includes a cylinder 4 with hydrogen, a cylinder 5 with argon and a cylinder 6 with a reducing gas mixture, designed for cleaning oxides of heavy liquid metal coolant and circuit and at the same time is used to clean the filter. The filter is provided in the upper part of the housing 2, for example in the cover, a pipe 7 for supplying a reducing gas mixture and a pipe 8 for removing water vapor to a condenser.

The operation of the TZhMT purification filter in the technological mode of purification from the coolant oxides of the surfaces of a nuclear reactor is as follows.

The basis for filter cleaning is either an unacceptable increase in the oxide content, or routine cleaning (according to the specified cleaning time), or cleaning after decompression of the circuit for the period of repair or as a result of an accident, or cleaning of the liquid fuel before filling the circuit.

In cylinder 6, a reducing gas mixture is prepared by supplying gas from cylinders 5 and 4 and it is fed discretely or continuously to a filter heated to a temperature of 350-450 ° C with discharge of reaction products into tank 1 or into a circuit.

Thus, impurities - lead oxides, which are in the filter and “clogged” the filter element, are reduced by hydrogen to form “pure” lead and water vapor. Water vapor and, in part, a reducing gas mixture are discharged from the filter discretely or continuously. Water vapor condenses in the condenser.

The cleaning time is determined either by its regulation of 4-6 hours at a temperature of 400 ° C, or by a controlled non-decreasing hydrogen content in the gas mixture at the outlet of the filter.

Thus, ensuring effective cleaning of lead coolant and increasing the service life of the filter TZHMT cleaning 2 is achieved not by the use of ineffective filters requiring periodic cutting and replacement, but by a pipe located in the upper part of the filter, connected by a pipe with valves to the supply line of the reducing gas mixture, which is connected to gas cylinders containing hydrogen and argon.

Application of the proposed technical solution will allow:

to increase the efficiency of purification of liquid metal coolant based on lead or its alloys from impurities - coolant oxides, to exclude clogging of the filter element in the filter;

- to exclude the use of “cold” traps, hydrodynamic and mechanical filters, which have a significant mass and require cutting, burial and replacement with new ones, after inefficiency for cleaning lead and lead-bismuth coolants;

- to simplify and increase the efficiency of the means and measures for cleaning liquid metal coolant based on lead or its alloys from impurities - coolant oxides;

- reduce the amount of radioactive waste from the nuclear power unit.

Claims (1)

A filter for cleaning a heavy liquid metal coolant, comprising a housing with a filter element, characterized in that it is equipped in the upper part of the housing with nozzles connected to gas cylinders with a reducing mixture and to steam condensers.