JPH0123076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radioactivity monitoring device for releasing main steam into the atmosphere in nuclear power generation equipment, particularly in pressurized water type nuclear power generation equipment.

If the steam relief valve or safety valve in the main steam pipe is activated when a narrow tube of a steam generator in a pressurized water nuclear power generation facility leaks, radioactive materials contained in the main steam pipe will leak into the atmosphere. Therefore, such equipment must be equipped with a device for detecting radioactivity,
It is important to accurately know the amount of radioactivity that leaks out from nuclear power generation facilities and to take countermeasures based on this information.

Conventionally, when a steam generator leaks in a capillary, steam leaks into the atmosphere from the main steam relief valve or safety valve, and radioactivity leaks into the atmosphere. For example, based on radioactivity analysis in the primary coolant, the leaked radiation I was looking for ability. However, with this method, in order to determine the amount of radioactivity leaked from each valve, many steps are required, including sampling analysis of the primary coolant, calculation of the leak rate of the steam generator, and calculation of the amount of steam released from each valve. It had the disadvantage of being time consuming.

SUMMARY OF THE INVENTION An object of the present invention is to provide a radioactivity monitoring device for releasing main steam into the atmosphere, which can accurately and quickly calculate the amount of radioactivity using a simple device.

In the present invention, in order to achieve this objective, a valve operation detector is attached to each of the main steam relief valve and the main steam safety valve that are attached to the main steam pipe drawn out from the steam generator in nuclear power generation equipment, A signal from a main steam pressure gauge and a signal from a valve operation detector installed in the same main steam pipe are connected to an outflow steam amount calculator, and a radiation detector is further provided near the outer wall of the main steam pipe. This device is characterized in that this and an outflow vapor amount calculator are connected to a released radioactivity amount calculator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings showing one embodiment thereof.

As shown in the figure, steam generated by heat exchange with a primary coolant contained in a steam generator 1 is drawn out through a main steam pipe 2 and sent to a turbine (not shown). A main steam pressure gauge 4, a main steam relief valve 5, and several sets of main steam safety valves 6 are connected to the main steam pipe 2 in this order, and when these valves 5 and 6 operate, , steam flows out from these valves 5 and 6, but if by any chance a capillary leak occurs in the steam generator 1, radioactive materials will flow out from the valves 5 and 6 into the atmosphere together with the steam. This will result in leakage. In this case, main steam pipe 2
The concentration of radioactive substances in the main steam pipe 2 is measured by a radiation detector 6 installed near the outer wall of the main steam pipe 2 and in front of the main steam pressure gauge 4. A valve operation detector 7 is attached to each main steam relief valve 5 and safety valve 6 to detect the opening and closing of the valve, and these are connected to an outflow steam amount calculator 8. A main steam pressure gauge 4 located on the upstream side is also connected. Furthermore, the radiation detector 3 and the outflow vapor amount calculator 8 are as follows:
It is connected to the emitted radioactivity amount calculator 9.

In this way, when the outflow steam amount calculator 8 confirms the opening and closing operating states of the main steam relief valve 5 and the main steam safety valve 6 using the valve operation detector 7, the outflow steam amount calculator 8 detects the main steam pipe 2.
The amount of leaked steam can be calculated based on the steam pressure inside. Furthermore, since the outflow steam amount calculator 8 is connected to the emitted radioactivity amount calculator 9, the amount of radioactive material that leaks outside when a heat transfer tube leaks or the like occurs in the steam generator 1 is calculated as radiation. From the radioactivity level in the main steam detected by the detector 3 and the amount of outflow steam determined by the outflow steam amount calculator 8, it can be easily determined by the emitted radioactivity amount calculator 9. can.

In this way, in the present invention, for example, 100
In the case of a 10,000 kW class facility, it is assumed that four steam generators 1 are installed, and the steam generated from each steam generator 1 is led through each main steam pipe 2 and sent to the main steam header. After merging, the steam is sent to the turbine, but assuming that each main steam pipe 2 is equipped with a main steam pressure gauge 4, a main steam relief valve 5, a main steam safety valve 6, etc., as described above. 1. When a heat transfer tube leaks or breaks in any of the steam generators 1, the reactor coolant containing radioactivity leaks into the steam side (secondary cooling system), causing radioactivity in the steam. Substances may be mixed in,
For example, at this time, if the nuclear power generation equipment loses power supplied from outside, many main steam relief valves 5 and safety valves 6 installed in the main steam pipe 2 belonging to the steam generator 1 (in this example In this case, a total of 8 valves are operated, and the steam in the main steam pipe 2 flows out into the atmosphere from the temporarily operated valves 5 and 6.

Therefore, a radiation detector 3 is installed near the outer wall of the main steam pipe 2 upstream of the main steam relief valve 5 and the safety valve 6 to measure the radiation caused by the radioactivity mixed into the main steam when the heat transfer tube leaks. By this, the level of radioactivity contained in the main steam pipe 2 can be known.

In addition, the flow rate of steam flowing out from the relief valve 5 and the safety valve 6 is determined by the valve operation (open, open, etc.) attached to each valve 5, 6.
From the signal of the closed) detector 7 and the value of the main steam pipe pressure gauge 4, the released steam amount calculator 8 connected to these pressure gauges 4 and detector 7 calculates the amount of steam released, and the radiation detector 3 and The total released radioactivity amount can be easily determined by the released radioactivity amount calculator 9 connected to the released steam amount calculator 8.

As described above, according to the present invention, in the event of a leakage in the heat transfer tube of the steam generator in nuclear power generation equipment, particularly in pressurized water type nuclear power generation equipment, the main steam relief valve When steam containing radioactive materials flows out from a safety valve, the amount of radioactivity that has flowed out can be easily and continuously determined. Therefore, it is possible to provide an extremely effective device as a safety measure in nuclear power generation equipment according to the present invention. can.

[Brief explanation of drawings]

The figure is a schematic diagram showing a radioactivity monitoring device when main steam is released into the atmosphere according to the present invention. 1...Steam generator, 2...Main steam pipe, 3...Radiation detector, 4...Main steam pressure gauge, 5...Main steam relief valve, 6
...Main steam safety valve, 7...Valve operation (open, close) detector,
8...Outflow vapor amount calculator, 9...Release radioactivity amount calculator.

Claims (1)

[Claims] 1 In nuclear power generation facilities, a valve operation detector is attached to each of the main steam relief valve and main steam safety valve that are installed on the main steam pipe leading out from the steam generator, and the main steam safety valve that is also installed on the main steam pipe an outflow steam amount calculator that receives signals from the steam pressure gauge and each of the valve operation detectors and calculates the outflow steam amount;
A radiation detector is installed near the outer wall of the main steam pipe,
Radiation at the time of release of main steam into the atmosphere in a nuclear power generation facility, characterized in that it is constituted by a radioactivity amount calculator that receives a signal from the radiation detector and a signal from the outflow steam amount calculator and calculates the amount of outflow radioactivity. performance monitoring device.