JPH03186797A - Failed fuel detecting device - Google Patents

Abstract

PURPOSE:To facilitate a control, to prevent a piping from being heated locally and to simplify the failed fuel detecting device by leading a cover gas outlet pipe and a liquefied gas outlet pipe of a tug gas collecting device and a cover gas separating device to a single heat storage tank and executing a heat exchange. CONSTITUTION:The device is constituted so that a cover gas outlet pipe 6a and nitrogen gas outlet pipes 4a, 4b and 5 of tug gas collecting devices 1a, 1b and a cover gas separating device 2 of a fuel detecting device are led to a single heat storage tank 11 and a heat exchange is executed. In such a state, a piping in which low temperature gas and high temperature gas flow is allowed to pass through the inside of the heat storage tank 11 whose temperature is controlled to 30 deg.C - 50 deg.C being a little higher temperature than the room temperature, by which these gas is brought to heat exchange with the liquid in the heat storage tank 11, and a temperature of gas is allowed to rise and fall, and it is exhausted to the downstream in a roughly room temperature state. By the heat exchange with gas, the liquid in the heat storage tank 11 is brought to temperature rise and temperature fall, and it is detected by a thermometer 14 inserted into the heat storage tank 11, and through a controller 17, the output of an electric heater 12 is controlled and opening and closing of a cooling water inlet valve are controlled, and the temperature of a liquid in the heat storage tank 11 is controlled and held at little higher temperature than the room temperature.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention detects the location of damage to a nuclear fuel assembly disposed in the core of a fast breeder reactor that uses a coolant such as liquid metal sodium. This article relates to a device for detecting damaged fuel using the tag gas method.

(Prior art) A damaged fuel detection device using the tag gas method seals tag gas into the fuel rods of a nuclear fuel assembly placed in the reactor core as a mark indicating the address of the nuclear fuel assembly. Since tag gas leaks from the damaged part and mixes with the cover gas, it is possible to detect which address of the fuel rod is damaged by analyzing the tag gas components in the cover gas. The cover gas is an inert gas such as argon gas filled in the cover gas space covering the surface of the liquid sodium coolant for cooling the core.

In addition, rare gases such as xenon and krypton and their isotopes are used as tag gases.

A conventional damaged fuel detection device using the tag gas method will be explained with reference to FIG.

That is, as shown in Figure 2, the reactor cover gas system A
The cover gas containing the tag gas flows into the tag gas recovery device 1 (in the figure, there are two devices, so they are indicated by Ia and lb; one device is on standby).

In this tag gas recovery device 1, rare gas is cryogenically adsorbed by cryogenic adsorption using activated carbon. The cryogenic adsorption method is a method in which a low concentration tag gas, such as a rare gas isotope such as xenon or krypton, contained in the cover gas is adsorbed onto activated carbon at a cryogenic temperature of about 180'C to concentrate it.

The cover gas containing the tag gas adsorbed by the tag gas recovery device 1 is heated to about 1500°C, separated, and sent to the cover gas separation device 2 through the cover gas inlet pipes 2a and 2b. The cover gas separation device 2 is filled with activated carbon, and after cryogenically adsorbing and concentrating the rare gas again, it is heated to about -80°C.
After selectively separating only the tag gas in the cover gas, the gas is heated to about 150° C. to separate the tag gas, and the tag gas is sent to the analyzer 3 through the tag gas outlet pipe 7. The analyzer 3 analyzes the components of the tag gas, that is, rare gas isotopes, and based on the results, it is possible to determine which fuel rod in the core is damaged.

In this way, the tag gas concentration is concentrated to a concentration that can be analyzed by the two-stage activated carbon cryogenic adsorption and selective separation of the cover gas in the tag gas recovery device 1 and the cover gas separation device 2, and the component analysis of the tag gas is performed in the analyzer 3. to detect the location of fuel damage within the core.

Here, the cryogenic state of -180°C is the tag gas recovery device 1,
This is carried out by supplying and spraying liquid nitrogen from the liquid nitrogen supply system C to the cover gas separation device 2 and cooling it.

The liquid nitrogen is vaporized in each device 1.2 and discharged as a cryogenic gas through the outlet tube 4 a% 4 bs 5.

Meanwhile, the cover gas is also cooled to a cryogenic temperature and flows out from the outlet pipes 6a, 6b, 7 of each device 1.2.

In this state where the rare gas of the cover gas and tag gas is cryogenically adsorbed by the activated carbon, extremely low temperature gas is released from the tag gas recovery device and the cover gas separation device 2.

On the other hand, in the step of heating to about 150° C. and separating the rare gas, gas at about 150° C. is released from the outlet of the device 2.

As mentioned above, if the extremely low or high temperature gas released from each device 1.2 flows into the reactor cover gas system A1 air conditioning system B1 analyzer 3 and waste gas treatment system at the same temperature, it will cause a functional problem. In order to cause

Conventionally, as a method for raising the temperature, a method has been adopted in which an electric heater 8 is attached to the surface of the outlet piping of each device 1.2 and heated. In this case, a thermometer 9 is provided on the surface of the pipe to monitor the temperature of the pipe, and the electric heater 8 is controlled by the controller 10.
It is necessary to adjust the output of

In addition, as a high temperature method, a method using heat radiation from the surface of the pipe is implemented. In this case, it is necessary to ensure the piping length necessary for heat radiation.

(Problems to be Solved by the Invention) However, the system temperature raising/lowering means in the conventional damaged fuel detection device has the following problems.

[11 Regarding temperature raising method (1) Because the gas flow rate and heat capacity at the device outlet are different,
Control is complicated as it is necessary to adjust the output of each heater individually.

(2) The piping directly under the heater may become locally hot and exceed the maximum operating temperature.

[21 Regarding the temperature lowering method (1) Since heat is naturally radiated from the surface of the piping, it is not only necessary to ensure the necessary length of the piping depending on the gas flow rate and heat capacity, but also the length of the piping becomes long.

In other words, overall, there was a problem in that the temperature had to be raised and lowered using separate methods for each piping section.

The present invention was made in order to solve the above problems, and it is possible to raise and lower the temperature of the system in the same piping section, and to raise and lower the temperature of multiple pipings at once, making control easier. It is an object of the present invention to provide a damaged fuel detection device that does not reach high temperatures and can be simplified.

[Effects of the Invention] (Means for Solving the Problems) The present invention allows cover gas containing tag gas sampled from a reactor cover gas system to flow into a tag gas recovery device, and collects the tag gas and cover gas by cryogenic adsorption. The recovered tag gas and cover gas are heated and flow into the cover gas separator, where the tag gas and cover gas are cryogenically adsorbed and concentrated, and the concentrated gas is heated to remove the cover in the concentrated tag gas and cover gas. In a damaged fuel detection device that has a system that selectively desorbs only gas and then heats it and introduces the tag gas into the analyzer, the cover gas outlet pipe and the liquefied gas outlet pipe of the tag gas recovery device and the cover gas separation device are simply connected. It is characterized by being configured so that it is guided to one heat storage tank for heat exchange.

(Function) The outlet pipes of the tag gas recovery device and the cover gas separation device are collected and connected to the downstream side through a heat storage tank.

The heat storage tank is filled with a liquid (for example, water) and is equipped with a thermometer for detecting the temperature of the liquid, an electric heater for raising the temperature of the liquid, and a heat exchanger tube for lowering the temperature. The heat transfer tube is connected to the cooling water system, and the cooling water is passed through the heat transfer tube to lower the temperature of the liquid. A valve is provided in the piping from the cooling water system, and upon receiving the output signal from the thermometer, the output of the electric heater and the opening/closing of the valve are adjusted by a controller.

By adjusting the output of the electric heater and the amount of cooling water, heat is exchanged through the outlet piping of the tag gas recovery device and the cover gas separation device in the temperature-controlled heat storage tank.

The temperature of the heat storage tank is adjusted to approximately 300C to 50C, which is slightly higher than room temperature.When low temperature gas is released from the outlet of the device, the temperature is raised, and when high temperature gas is released, the temperature is lowered, and the temperature is lowered to room temperature ( (approximately 10°C to 40°C).

(Embodiment) An embodiment of the damaged fuel detection device according to the present invention will be described with reference to FIG.

Reference numeral A in Figure 1 indicates the reactor cover gas system, and this reactor cover gas system A contains the cover gas covering the surface of the liquid metal sodium coolant in the fast breeder reactor, and the damaged fuel contained in this cover gas. Contains tag gas leaked from the rod. The cover gas is, for example, argon gas, and the tag gas is a rare gas such as xenon or krypton, or its isotope.

The cover gas derived from the reactor cover gas system A is carried out by the tag gas recovery device 1 (in the figure, two units are provided, one of which is on standby and is shown as the a system and the b system, respectively, to avoid duplication of explanation. To avoid this, only the A line will be explained). A cover gas inflow pipe 2a for flowing concentrated cover dregs into the cover gas separation device 2 is connected to the outlet side of the tag gas recovery device 1a. Further, a nitrogen gas outlet pipe 4a and a cover gas outlet pipe 6a are connected to the outlet side of the recovery device 1a. Similarly, a cover gas inflow pipe 2a, a nitrogen gas outlet pipe 4a, and a cover gas outlet pipe 6a are connected to the other tag gas recovery device. A nitrogen gas outlet pipe 5 that flows into the air conditioning system B and a cover gas outlet pipe 7 that connects to the analyzer 3 are connected to the cover gas separation device 2 . The nitrogen gas outlet pipes 4a, 4b, 5 and the cover gas outlet pipes 6a, 6b, 7 are inserted into the heat storage tank 11. An electric heater 12, a heat exchanger tube 13, and a thermometer 14 are incorporated in the heat storage tank 11. The heat exchanger tube 13 is connected to the cooling water system E, and the inlet pipe 1 of the cooling water system E
5 is provided with a valve 16. electric heater 12
, the thermometer 14 and the valve signals are input to the controller 17.

Therefore, in the damaged fuel detection device having the above configuration, by passing the pipes through which the low-temperature gas and high-temperature gas flow through the heat storage tank 11 whose temperature is adjusted to a temperature slightly higher than room temperature (30°C to 50°C), these gases can be detected. The gas exchanges heat with the liquid in the heat storage tank 11, raises and lowers the temperature of the gas, and is discharged downstream at approximately room temperature.

Through heat exchange with the gas, the temperature of the liquid in the heat storage tank 1 is lowered or increased. This is detected by the thermometer 14 inserted into the heat storage tank 11, and the electric heater 12 is controlled via the controller 17. By adjusting the output and opening/closing the cooling water valve, the temperature of the liquid in the heat storage tank 11 is adjusted and maintained at a temperature slightly higher than room temperature.

Note that the flow and separation method of the sampled tag gas and cover gas from the reactor cover gas system A to the analyzer 3 are the same as in the conventional example, and therefore their description will be omitted to avoid duplication.

The embodiment described above has the following effects.

(1) Tag gas recovery device 1 and cover gas separation device 2
The low temperature or high temperature gas released from the heat storage tank 11 is heated and cooled, and is then released downstream at approximately room temperature.

(2) Even when low-temperature gas and high-temperature gas flow alternately in a pipe, a single heat storage tank 11 can raise the temperature of the low-temperature gas and lower the temperature of the high-temperature gas.

(3) The liquid in the heat storage tank 11 is regulated and maintained at a temperature slightly higher than normal temperature, and the surface temperature of the piping does not locally rise to a high temperature, unlike when using a conventional electric heater.

(4) The tag gas recovery device, the cover gas outlet pipe of the cover gas separation device, and the nitrogen gas outlet pipe, a total of six pipes, are passed through the heat storage tank 11, so the temperature can be adjusted only in the heat storage tank 11. Easier to control. Furthermore, it is advantageous in terms of thermal energy because heat exchange can be performed between low temperature gas and high temperature gas.

In the above embodiment, the temperature of the heat storage tank 11 is lowered indirectly by passing the cooling water through the heat transfer tubes in the heat storage tank. It is also possible to lower the temperature of the liquid in the tank.

In this case, the temperature lowering effect is greater than in the example, and there is an advantage that only a small amount of cooling water is required.

Moreover, the electric heater in the heat storage tank can also be wrapped around the piping in the tank.

In particular, the nitrogen gas outlet pipe has a large flow rate of cryogenic nitrogen gas flowing inside and has a large heat capacity. Therefore, the liquid in the tank may solidify near the inlet of the heat storage tank 11. Furthermore, by wrapping an electric heater around the piping inside the heat storage tank, the temperature raising effect can be further enhanced and solidification of the liquid can be prevented.

Furthermore, the piping immediately below the electric heater can be prevented from reaching a high temperature locally by interposing the liquid in the heat storage tank in the gap between the electric heater and the piping.

[Effects of the Invention] According to the present invention, by raising and lowering the temperature of the system in the same piping section and raising and lowering the temperature of a plurality of pipes together in a heat storage tank, temperature control is facilitated, and the piping can be locally heated to a high temperature. It is possible to prevent this from happening. Furthermore, the electric heater, thermometer, and controller that were conventionally provided in each pipe can be eliminated, and the apparatus can be simplified.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of a damaged fuel detection device according to the present invention, and FIG. 2 is a system diagram showing a conventional damaged fuel detection device. A... Reactor cover gas system B... Air conditioning system C... Liquid nitrogen supply system D... Waste gas treatment system E... Cooling water system 1... Tag gas recovery device 2... Cover gas Separation device 3...Analysis number device 4...Nitrogen gas outlet pipe 5...Nitrogen gas outlet pipe 6...Cover gas outlet pipe 7...Tag gas outlet pipe 8...Electric heater 9... Thermometer 10... Controller 11... Heat storage tank 12... Electric heater 13... Heat exchanger tube 14... Thermometer 15... Cooling water inlet pipe 16... Pulp 17... Controller ( 8733) Agent: Yoshiaki Inomata, patent attorney (and others)
1 person) Figure

Claims (1)

[Claims] The cover gas containing the tag gas sampled from the reactor cover gas system flows into the tag gas recovery device, where the tag gas and cover gas are collected by cryogenic adsorption, and the recovered tag gas and cover gas are heated to separate the cover gas. The tag gas and cover gas that flow into the device are cryogenically adsorbed and concentrated, and the concentrated gas is heated to selectively separate only the concentrated tag gas and cover gas from the cover gas. A broken fuel detection device having a system for introducing it into an analysis device, wherein the cover gas outlet pipe and the liquefied gas outlet pipe of the tag gas recovery device and the cover gas separation device are guided to a single heat storage tank for heat exchange. A damaged fuel detection device featuring: