RU2267177C1 - Device for neutralization of the liquid a-wastes of the low and medium level of radioactivity - Google Patents

Abstract

FIELD: atomic power; liquid A-wastes processing.

SUBSTANCE: the invention is pertaining to the field of atomic power, in particular, to the liquid A-wastes processing. The invention contains: a device for neutralization of the liquid A-wastes of low and medium level radioactivity, which contains an upright located vaporizing container placed inside a ring-type tank. The vaporizing tank has a heater located in its middle part and louvered deflectors and a branch pipe of a condensate withdrawal - located in its upper part. The vaporizing tank is made in the form of the shut funnel with its narrow part directed downward. The bottom of the shut funnel represents a replaceable cylinder with a sorbent and is placed inside the second heater. The ring-type tank having a branch pipe to feed the processed solutions is connected to the vaporizing tank by a pipeline with a pressure-relief valve. Advantage of the invention is an improved efficiency of water purification.

EFFECT: the invention ensures improved efficiency of water purification.

1 dwg

Description

The invention relates to the field of processing liquid radioactive waste of low and medium levels of activity generated in the contour waters of nuclear submarine reactors (NPS) that have exhausted their life.

The known design of the evaporator with forced circulation (A. S. Nikiforov, V. V. Kulichenko, M. I. Zhikharev. Neutralization of liquid radioactive waste. M: Energoatomizdat, 1985, p. 23, Fig. 2.6). This solution is unreliable due to the presence in the design of moving parts - the pump and compressor. Additional measures are required for further processing of the brine.

The closest is the stationary design of the evaporator with a remote heating chamber and natural circulation (A. S. Nikiforov, V. V. Kulichenko, M. I. Zhikharev. Neutralization of liquid radioactive waste. M: Energoatomizdat, 1985, p. 22, Fig. .2.5). The design contains a heating chamber using steam as a heat carrier, as well as a plate column designed to clean juice vapors from drip and aerosol entrainment.

The disadvantage of this apparatus is the production of an evaporated solution (brine), which requires additional operations and equipment for its further processing.

The technical result of this device is the ability to simultaneously carry out the evaporation process to obtain condensate suitable for discharge into the water area, and to concentrate the brine obtained during the evaporation process, followed by its precipitation on the sorbent.

The technical result is achieved in that the device is a vertically arranged evaporation tank placed inside an annular tank, in the middle part of which a heating element is placed. At the top of the evaporation tank are louvre chippers. The evaporation tank is made in the form of a closed funnel, a narrow part down. The bottom of the tank is a removable cup with a sorbent placed in the internal volume of the sorbent heater. An annular tank having a pipe for supplying processed solutions is connected to the evaporation tank by a pipeline with a check valve. The evaporation tank is closed with a lid with a condensate drain pipe.

The drawing shows a device for the disposal of liquid radioactive waste of low and medium levels of radioactivity. It is an evaporation tank (1) located inside the annular tank (2). In the upper part of the evaporation tank (1), louvre chippers (3) are placed. The evaporation tank (1) is closed by a cover (4) with a condensate drain pipe (5). The evaporator heater (6) is located in the middle part of the evaporation tank (1). In the lower part of the evaporation tank (1) there is a removable cup (7) with a sorbent (8). A replaceable cup (7) with a sorbent (8) is, in turn, located in the internal volume of the heater (9) of the sorbent (8). With the main volume of the evaporation tank (1), a removable cup (7) with a sorbent (8) is connected by a flange connector (10) to a fine mesh network (11), which prevents the sorbent from being carried away. An annular tank (2) having a nozzle for supplying processed solutions (12) is connected to the evaporation tank (1) by a feed pipe (13) with a check valve (14) preventing the solution from being thrown from the evaporation tank into the annular tank. There can be two feed pipelines (13).

The device operates as follows.

The annular tank (2) is filled through the nozzle for supplying the processed solutions (12) to a certain level with liquid radioactive waste. The processed solution enters the evaporation tank (1) from the annular tank (2) through the feed pipe (13). The reverse movement of the solution is eliminated due to the presence of a non-return valve (14) on the pipeline (13). Thus, in the evaporation tank (1) and the annular tank (2) the same level of the processed solution is established. When the upper layers of the solution are heated by the heater (6) in the evaporation tank (1) to a temperature slightly below the boiling point of a particular solution, the process of evaporation from the surface occurs. The resulting vapors condense on the louvre chippers (3) located in the upper part of the evaporation tank (1). Secondary steam through the condensate drain pipe (5) enters the collection tank with a high degree of purification of condensate from radionuclides. As the level of the processed solution in the evaporation tank (1) decreases, the solution from the annular tank (2) through the feed pipe (13) with a check valve (14) enters the evaporation tank (1) due to the difference in hydrostatic pressure in both tanks. When conducting control analyzes in the collection tank, provided that the MPC values are below the standard, the water from the collection tank is discharged into an open reservoir or water area. When determining MPC values approaching the normative, the flow of the solution to distillation is stopped. The power supply to the evaporator heater (6) is cut off and the power supply to the heater (9) begins. The brine accumulated in the evaporation tank (1) during the heating process is evaporated to dryness in the presence of a sorbent (silica gel). In this case, sorption of radionuclides dissolved in brine occurs. After the deposition of radionuclides on the sorbent, the heater (9) is turned off. The distillation process is resumed, electricity is supplied to the heater (6) of the evaporation tank (1). In the annular tank (2), a solution is pumped to a certain level for processing. When conducting several cycles (the specific amount of the latter depends on the composition of the initial solution), the sorbent (bearing) capacity of the sorbent will reach the limit values for some elements contained in the brine (calculated theoretically from the initial composition). In this case, the glass (7) with a saturated dry sorbent (8) is removed from the heater body (9) and sent for disposal. With a renewed portion of the sorbent (8), the apparatus is again ready to produce conditioned condensate. To reduce the content of radionuclides in the surface layer of the sorbent granules in the case of the evaporation tank (1), it is possible to steam the granules with nitric acid.

This device is compact and can be installed on a transported platform.

The proposed design has several advantages over known devices:

- the brine obtained during the evaporation process is deposited on the sorbent within the same structure to obtain solid granules suitable for subsequent disposal;

- lack of moving parts;

- less metal, small dimensions, the ability to create mobile installations;

- improved thermodynamic characteristics.

Claims (1)

A device for the disposal of liquid radioactive waste of low and medium levels of radioactivity, containing an evaporation tank, characterized in that the vertically located evaporation tank, placed inside the annular tank and having a heater in the middle part and louvre chippers in the upper part, is made in the form of a closed funnel narrow part down, the bottom of which is a removable cup with a sorbent placed in the volume of the second heater, and an annular tank having a pipe for supplying processed solutions nen with an evaporation tank by the pipeline with the backpressure valve, the evaporation tank is closed by a cover with a condensate branch pipe.