JPH0321884A - Radioactive material sampling device - Google Patents

Abstract

PURPOSE:To remove a piping joint, etc., which obstructs a flow and to perform purging operation effectively by installing piping for purging on the gas outlet side of piping for circulation and providing a means which supplies purging air in the opposite direction at the time of the purging from that at the time of sampling. CONSTITUTION:A pump 5 for circulation and a pump 6 for collection can be inverted in flowing direction. For the sampling operation, an exit-side valve 9 is opened and a purging valve 10 is closed; and the pumps 5 and 6 are put in operation to supply sample gas as shown by an arrow. At this time, dust and iodine in the sample gas are collected by a sample collector 7. When the exit-side valve 9 is closed and the purging valve 10 is opened after the collection, the pumps 5 and 6 are operated in the opposite directions to supply the sample gas as shown by an arrow B, thereby removing dust and iodine caught at the piping joint part, etc.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is used in nuclear power plants, etc., to collect dust and iodine in order to monitor the radioactivity in the exhaust gas released. This is related to the collection device. ``Prior art'' Figure 3 shows a conventional radioactive material sampling device, in which the device body (1) includes circulation piping (2), purge piping (3).
A collection pipe (4) branched from the circulation pipe (2) at the Aa and Ab sections is installed, and the circulation pipe (2)
and collection piping <4) are pumps (5a),
(6a). The collection pipe (4) is equipped with a sample collector (4) that collects dust and iodine in the gas passing through it.
7) and a sampling gas flow rate control valve (8). The circulation pipe (2>) and the purge pipe (3) are provided with inlet shutoff valves (9a) and (10), respectively. (11) is a purge gas cleaning filter.Circulation pipe (2>) flanges (l2) and (13) for connection with external piping are installed on the intake and exhaust sides of the At this time, arrow B is the direction of flow during purging.

Next, we will explain the operation. During sampling, the sample gas is sucked into the circulation pipe (2) connected to the external pipe by the flange (12) by the circulation pump (5a), passes through the open valve (9a), and enters the main body ( 1
) and then exhausted to an external pipe connected by a flange (13). This circulation pipe <2> is connected to the sample collector (7) without changing the state of dust or iodine in the external sample gas due to dew condensation or precipitation.
) It is necessary to flow a large flow rate so that sampling can be carried out within the range.

On the other hand, a part of the sample gas is sucked into the collection pipe (4) branched from the circulation pipe (2) by operating the collection pump (6a), and passes through the so-called flow control valve (8). The necessary amount of sample gas is passed through the sample collector (7) by the knot, and the dust and iodine in the gas is collected by the sample collector (7).Then, the collected gas is passed through the circulation path. Return to the interior.This collection pipe (2) only flows the amount necessary for sampling, so especially for highly concentrated radioactive gases, it is also necessary to suppress the radiation dose in the sampler (7) to a manageable amount. It is necessary to flow a small flow rate, so it is divided into two systems. In addition, after sampling, dust and iodine in the gas left in the pipes will cause measurement errors during the next sampling, so it is necessary to purge them. This purge involves closing the valve (9a), opening the valve (10), and turning on the pump (
By operating steps 5a) and (6a), the indoor air purified by the purge air filter (11) is caused to flow through the circulation and collection pipes (2) and (4), respectively.

[Problems to be Solved by the Invention] Since the conventional radioactive material sampling device is configured as described above, gas flows only in a certain direction, so there is no possibility that gas may flow inside the sample sampling device (7) or at the pipe joints. The trapped dust, iodine, etc. cannot be removed successfully even if the purge gas is flowed in the same direction. In other words, there was a problem in that it could not be effectively cleaned using barge gas. This invention was made to solve the above-mentioned problems, and the purpose is to obtain a radioactive material sampling device that can perform effective purging. [Means for Solving the Problems] In the radioactive material sampling device according to the present invention, the purge piping is installed on the gas outlet side of the circulation piping, and when purging, the piping is installed in the opposite direction from the sampling time. A means is provided for flowing the bargea. [Function] In this invention, during purging operation, the rotation of the pump is reversed so that the flow direction of the purge air is reversed to that during sampling, thereby removing dust, iodine, etc. caught on stepped parts such as pipe joints. Purge efficiently.

``Example'' Figure 1 shows an example of this invention, and in the figure, the circulation pump (5) and collection pump (6>) are each capable of reversing the flow direction. Other than that, the same symbols as in Fig. 3 are the same parts.
The explanation will be omitted.

With the above configuration, during sampling, the sampling valve (9) is open, the purge valve (10) is closed, and the circulation bomb 1 (5) and the collection bomb (6) are set so that the sample gas flows in the eight directions of the arrows. 〉. At this time, dust and iodine in the sample gas are collected by the sample collector (7). After this collection is completed, the sampling valve (9) is closed and the purge valve (10〉 is opened). In this case, the circulation pump (5) and collection pump (6)
) in the reverse direction and flow the sample gas in the direction of arrow B to remove dust, iodine, etc. caught in pipe joints, etc.

In the embodiment described in -E, the circulation pump (5) and collection pump (6) were provided with reversible pumps, but as shown in FIG. 2 as another embodiment, the pump (5a). (6
A combination of flow path switching valves such as a four-way switching valve (14) may be provided at the entrance and exit portion of a), and the same effect can be obtained.

[Effects of the Invention] As described above, according to the present invention, gas is made to flow in the opposite direction to that during sampling during purging, so that stepped portions such as piping joints that may get caught and cause noise in the flow direction during sampling. Also, dust, iodine, etc. from a part of the filter are removed, which has the effect of further enhancing the purging effect.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is a circuit diagram of another embodiment, and FIG. 3 is a circuit diagram of a conventional radioactive substance sampling device. (2)... is circulation piping, (3)... purge piping, (
4>・Collection piping, (5)...Circulation pump, <6)
... Collection pump, (9) ... Outlet valve, (10).
...Purge valve, <14) 4-way switching valve. In each figure, the same reference numerals indicate the same or equivalent parts. 14: RG direction

Claims (1)

[Claims] Pumps, valves, and circulation piping that circulate the sample gas;
A purge pipe branched from the circulation pipe and opened to the atmosphere via a valve, a pump, a valve, and a collection pipe forming a sample collection path that branches from the circulation pipe and joins together, and a sampling pipe. A radioactive material sampling device comprising: means for reversing the flow direction of fresh fluid during purge and purge times.