JPH0151160B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a gaseous waste treatment device for a nuclear reactor.

(Prior art) In general, in nuclear power plants, rare gases in the primary coolant are extracted using hydrogen gas as a carrier gas in a volume control tank in order to reduce the concentration of radioactive gaseous waste in the primary coolant. ing.

In other words, the extraction of rare gases from this primary coolant is necessary to reduce the radiation exposure of station workers who work near the piping through which the primary coolant flows. As a result, the concentration of radioactive gaseous waste in the primary coolant decreases as shown in FIG. That is, as the degassing efficiency increases, the radioactive gas concentration ratio decreases.

Batch treatment using a plurality of exhaust gas attenuation tanks is used as a method for treating radioactive gaseous waste after air extraction.

Although this treatment method is suitable for treating small amounts of radioactive gaseous waste, it requires many operating procedures, multiple system configurations, and complicated operations, and is also limited in equipment capacity. You can't expect big benefits. Furthermore, there is an increase in possible trouble factors due to the complicated system and complicated operations, so this method cannot be said to be suitable for nuclear power plants.

(Problems to be Solved by the Invention) The present invention has been made in response to such conventional circumstances, and by continuously processing radioactive gaseous waste contained in the primary coolant, system operation is facilitated and human The purpose of the present invention is to provide a gaseous waste treatment device that can reduce the number of trouble factors and also can reliably carry out hold-up treatment of rare gas at a constant flow rate.

[Structure of the Invention] (Means for Solving the Problems) That is, the gaseous waste treatment device of the present invention includes an exhaust gas extraction device that extracts radioactive gaseous waste contained in the primary coolant of a nuclear reactor, and an activated carbon rare gas hold-up device that continuously processes gaseous waste to attenuate the radioactivity of the rare gas contained in the radioactive gas waste; and a flow rate detector that connects the exhaust gas extraction device and the hold-up device. and a flow rate adjustment line connected downstream of the flow rate detector of this inflow line and supplying gas to the inflow line in accordance with the flow rate of the radioactive gas waste detected by the flow rate detector. It is characterized by becoming.

(Function) In the gaseous waste treatment apparatus of the present invention having the above configuration,
Continuous processing of radioactive gaseous waste contained in the primary coolant facilitates system operation, reduces human-caused troubles, and ensures hold-up processing of rare gases at a constant flow rate. It can be carried out.

(Example) The details of the present invention will be described below with reference to an example shown in the drawings.

Fig. 2 shows a gaseous waste treatment system according to an embodiment of the present invention. A volume control tank inserted into the coolant extraction line 2 is shown. A hydrogen gas supply device 3 is connected to this volume control tank 1, and radioactive gas waste accumulated in the volume control tank 1 and hydrogen gas supplied from the hydrogen gas supply device 3 are connected downstream of the volume control tank 1. A front exhaust gas extractor 4 for extracting air is provided. A hydrogen gas treatment device 5 is disposed downstream of the front exhaust gas extraction device 4, and the downstream side of the hydrogen gas treatment device 5 is connected to a hold-up device 6. This hold-up device 6 includes a pre-filter 8 for capturing daughter nuclides generated from short-lived nuclides and for protecting an activated carbon rare gas hold-up tower 7 described below, and a pre-filter 8 disposed downstream of this to hold the rare gas. Activated carbon rare gas hold up tower 7
and a post-filter 9 that is disposed downstream of this and captures daughter nuclides generated during hold-up. On the downstream side of this hold-up device 6, there is a rear exhaust gas extraction device 10 for extracting radioactive gas waste from the hold-up device 6.
is provided, and the downstream side of this rear exhaust gas extraction device 10 is connected to an exhaust stack 11. Further, one end of the pipe connecting the volume control tank 1 and the front exhaust gas extraction device 4 is connected to a vent collecting pipe that collects the equipment vents 13 or the other end of a vent gas transfer line 16 that is connected to the tank 14. . Further, a flow rate adjustment line 17 is connected to the inflow line 12 that connects the hydrogen gas treatment device 5 and the hold-up device 6, and a ventilation air conditioner 18, a ventilation system blower 1, and a ventilation system blower 1 are connected to this flow rate adjustment line 17 in order from upstream.
9. A flow rate regulating valve 20 is inserted. A flow rate detector 21 is inserted upstream of the connection point of the flow rate adjustment line 17 of the inflow line 12.

In the figure, reference numeral 22 denotes a flow rate detector 21 flowing through the inflow line 12 detected by the flow rate detector 21.
Flow rate signal S1 is input to the hold up device 6.
A flow rate adjustment valve control device is shown that controls the opening degree of the flow rate adjustment valve 20 so that the flow rate, which is the sum of the radioactive gaseous waste flowing into the flow rate adjustment line 17 and the air flowing in from the flow rate adjustment line 17, is a constant value. A pressure detector 23 is interposed between the hold-up device 6 and the rear exhaust gas extraction device 10, and a circulation line 25 is formed in the rear exhaust gas extraction device 10 to which a pressure control valve 24 is inserted.

In the figure, reference numeral 26 denotes a pressure control valve control which inputs the pressure signal S2 detected by the pressure detector 23 and controls the opening degree of the pressure control valve 24 so that the pressure at the position of the pressure detector 23 becomes a constant value. The device is shown.

In the gaseous waste treatment device configured as described above, radioactive gaseous waste contained in the primary coolant flowing into the volume control tank 1 from the primary coolant extraction line 2 is supplied from the hydrogen gas supply device 3. By continuous purge of carrier gas, hydrogen gas,
It is extracted together with hydrogen gas by the front exhaust gas extractor 4. At the same time, however, because the front exhaust gas extraction device 4 extracts vent gas from the vent manifold or tank 14, the concentration of extracted hydrogen gas is diluted.

The radioactive gas waste and diluted hydrogen gas extracted in this way are transferred to the hydrogen gas processing device 5.
Hydrogen gas is removed. The radioactive gaseous waste mainly consisting of radioactive rare gas is then sent to the hold-up device 6. On the other hand, fluctuations in the flow rate of this radioactive gaseous waste are constantly monitored by a flow rate detector 21 inserted on the inflow line 12, and the flow rate of the radioactive gaseous waste flowing through this inflow line 12 is kept at a predetermined constant value. When the amount decreases, the opening degree of the flow rate adjustment valve 20 is increased by the flow rate adjustment valve control device 22, and the amount of gas (air) corresponding to the decreased flow rate of radioactive gas waste is increased.
is supplied to the inlet line 12 from the ventilation air conditioner 18 .

Therefore, the flow rate of gas flowing into the hold-up device 6 is always constant. The radioactive gaseous waste that has flowed into the hold-up device 6 is captured by the prefilter 8, where daughter nuclides generated from short-lived nuclides are captured, and the activated carbon rare gas hold holds up the rare gas contained in the radioactive gaseous waste. It flows into the uppowder 7.

The hold-up time T of this activated carbon type rare gas hold-up tower 7 can be expressed as T=K·W/Q. where K: dynamic adsorption coefficient (m ³ /ton),
W: Activated carbon weight (ton), Q: Air flow rate (m ³ /hr)
It is. The rare gas held up by the activated carbon type rare gas hold up tower 7 is passed through the downstream filter 9.
The daughter nuclides generated during hold-up are captured, extracted by the rear exhaust gas extractor 10, and released into the atmosphere from the exhaust stack 11.

However, since the pressure at the position of the pressure detector 23 is always kept constant by the pressure control valve control device 26 which inputs the pressure signal S2 from the pressure detector 23 and controls the opening degree of the pressure control valve 24, the hold-up The pressure within the device 6 is also constant.

In the gaseous waste treatment apparatus configured as described above, rare gas can be continuously processed by the hold-up device 6, facilitating system operation and reducing human-induced trouble factors. In addition, in the gaseous waste treatment system for a pressurized water reactor configured as described above, hold-up processing of rare gas is always performed at a constant flow rate and pressure, so that unattenuated radioactive materials are discharged from the hold-up device 6. The fear of being discharged into the atmosphere through the exhaust stack 11 is eliminated.

[Effects of the Invention] As described above, according to the gas waste treatment device of the present invention, it is possible to continuously treat radioactive gas waste contained in the primary coolant, and as a result,
System operation becomes easier, human-caused troubles can be reduced, and rare gas hold-up processing can be performed reliably at a constant flow rate.

[Brief explanation of drawings]

FIG. 1 is a graph showing changes in radioactive gas concentration in the primary coolant due to degassing, and FIG. 2 is a piping system diagram showing an embodiment of the gaseous waste treatment apparatus of the present invention. 4...Exhaust gas extraction device, 6...Hold up device, 7...Activated carbon rare gas hold up tower,
17...Flow rate adjustment line, 21...Flow rate detector.

Claims (1)

[Claims] 1. An exhaust gas extraction device that extracts radioactive gaseous waste contained in the primary coolant of a nuclear reactor, and a device that continuously processes the radioactive gaseous waste to attenuate the radioactivity of the noble gas contained in this radioactive gaseous waste. an activated carbon-type rare gas hold-up device, an inflow line in which a flow rate detector is inserted that connects the exhaust gas extraction device and the hold-up device; A gaseous waste treatment device comprising: a flow rate adjustment line that supplies gas to the inflow line according to the detected flow rate of radioactive gaseous waste.