JPS603635B2 - How to constantly monitor the health of the reactor vessel - Google Patents

Description

Detailed Description of the Invention The present invention relates to the integrity of reactor vessels, guard vessels, and cells of various nuclear reactors including fast breeder reactors, and more specifically, to the integrity of reactor vessels, guard vessels, and cells of various nuclear reactors, including fast breeder reactors. The present invention relates to a method for monitoring the health of the component while in use by detecting the presence or absence of leakage of marker gas.

Conventionally, the integrity of the reactor vessel and its attached piping has been inspected using a television camera or the like on the weld lines of the reactor vessel, etc., and only during the period when the reactor is out of operation. However, with this indirect visual inspection method using a television camera, it is difficult to always reliably detect minute cracks, and it cannot be carried out while the furnace is operating, so there are problems in that it takes time to discover defects. Although they were manufactured and maintained with great care to prevent defects, there was still room for improvement in terms of safety in the event of an emergency. The present invention has been made in view of the actual state of the prior art, and its purpose is to cover not only the welded parts of the furnace vessel but also the entire surface of the furnace vessel including the piping connected to the furnace vessel and the guard vessel. An object of the present invention is to provide a method that can constantly monitor the overall health of the reactor even during operation, thereby further increasing the safety of the reactor.

In order to achieve such an object, according to the present invention, the space between the reactor vessel and the guard vessel enclosing the reactor vessel is made into a sealed structure, a marker gas is pressurized and sealed in this sealed space, and the marker gas is sealed. The system is configured to constantly monitor whether there is any leakage from the sealed space. Therefore, in the unlikely event that a crack occurs in the reactor vessel, guard vessel, or primary coolant pipe, it is possible to quickly detect the occurrence of an abnormal situation by detecting the leakage of marker gas from the crack. It can be done. Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 shows one embodiment of the present invention, in which a reactor vessel 2 housing a reactor core 1 and a guard vessel 3 enclosing the reactor vessel 2 are joined at a welding portion 4. The sealed space 5 is made into a closed space, and a marker gas is sealed in the sealed space 5 to be in a pressurized state, and a pressure gauge 6 for measuring the pressure in the sealed space 5, an upper cover gas space 7 of the furnace vessel 2, and A device configuration is being explored that includes marker gas detection mechanisms 8 and 9 that can detect the presence or absence of the marker gas in the gas area outside the guard vessel. The guard vessel 3 also covers the vicinity of the inlet piping section 10 and the outlet piping section 11 of the reactor coolant, but their extensions are provided with, for example, bellows (not shown) to form a closed space. In this way, in order to create a sealed structure in the space between the furnace vessel and the guard vessel, it is sufficient to weld them together, but in order to form a more reliable sealed space, the present inventor "Nuclear reactor" first proposed by
(Japanese Patent Application No. 56-7336) can be utilized.

FIG. 2 shows another embodiment utilizing such technology.

The space 5 between the furnace vessel 2 and the guard vessel 3 and the space outside the guard vessel pass through each other through the manometer structure 15, and the space 5 can be sealed by filling the manometer structure 15 with liquid. Moreover, it is possible to maintain a pressurized state, and the sealed space is filled with a marker gas. A level gauge 16 made of liquid sealing material is provided as a pressure gauge in a part of the manometer structure 15. Since the other configurations are almost the same as those in FIG. 1, the same reference numerals are given, and the description thereof will be omitted. If damage such as a crack occurs in the reactor vessel 2 or the primary cooling system piping connected to it, the sealed marker gas will enter the reactor vessel 2 from the damaged area and enter the reactor vessel 2 at the top of the reactor vessel. Since it leaks into the cover gas space 7 and the cover gas space (not shown) in the primary cooling system equipment, it is immediately detected by, for example, a marker gas detection mechanism 8 installed in the cover gas space 7, and the gas leaks into the reactor vessel 2. Damage can be detected early.

Further, if damage occurs to the guard vessel 3, the marker gas leaks into the outer space, and therefore can be similarly detected by the marker gas detection mechanism 9. In order to most easily detect the presence or absence of a leak of the marker gas, the marker gas is sealed in the sealed space 5 to a constant pressure within the range of, for example, about 1.5 to about 3 atm (absolute pressure). In the case of the embodiment shown in FIG.
The pressure change may be measured using a pressure gauge 6 attached to the guard vessel 3. Further, in the case of the embodiment shown in FIG. 2, changes in pressure can be monitored by using a manometer structure 15 and measuring changes in the liquid level with a level meter 16. When measuring pressure changes, it is necessary to compensate for volume changes due to temperature changes in the marker gas. Based on the pressure measurement by the pressure gauge 6 or the bell gauge 16 and the measurement results of the marker gas detection mechanisms 8 and 9, it is possible to accurately judge at all times whether there is any damage to the reactor vessel, guard vessel, etc. Further, as is clear from the above, at least one of the pressure gauge 6 or the pressure gauge 16 and the marker gas detection mechanisms 8, 9 may be provided, but they may of course be arranged side by side. In the method of the present invention, the indicator gas to be pressurized into the closed space 5 formed between the reactor vessel 2 and the guard vessel 3 is an inert gas such as helium gas, other rare gases, or a mixture thereof. is preferred.

Furthermore, the detection mechanism 8 for the marker gas used in the present invention,
9 can be applied to any mechanism that can identify the presence or absence of a marker gas, but usually a gas sampling device and a mass vector meter connected thereto are preferred.

In this case, it is preferable that the marker gas contains one that can be more sensitively sensed than the mass vector. For example, those added with specific stable isotopes of rare gases,
Alternatively, if a gas mixed at a specific ratio is used, the presence or absence of leakage of the marker gas can be quickly and reliably monitored. Examples of stable isotopes of rare gases include neon 20,
There are neon 21 and neon 22, but it is not limited to these. The present invention is applicable to any type of nuclear reactor that has a guard vessel attached to the reactor vessel.

Contrary to the above, by creating a negative pressure in the sealed space between the guard vessel and the furnace vessel with respect to the outside of the guard vessel and installing a gas detection mechanism in the sealed space, leakage from the outside space into this sealed space can be prevented. It is also possible to detect cracks in the guard cell by the method of detecting.

As is clear from the above explanation, according to the method of the present invention, the presence or absence of leakage of marker gas can be constantly monitored even during operation of the nuclear reactor, and in the event of an accident, abnormalities can be detected at an extremely early stage. Since it can be detected, it is possible to take thorough countermeasures, and the safety of nuclear reactors can be further increased.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of another embodiment. 1. ．． ．． ．． ...Furnace D, 2...Furnace vessel, 3...
・Guard vessel, 5... Closed space, 6...
・Pressure gauge, 8, 9... Marker gas detection mechanism, 1
5... Manometer structure, 16... Level meter. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. The space between the reactor vessel and the guard vessel surrounding it is made into a sealed structure, and a marking gas is sealed in this sealed space to be in a pressurized state, and the sealed space for the marking gas is sealed. A method for constantly monitoring the health of a reactor vessel or a guard vessel, which constantly monitors the presence or absence of leakage from the reactor vessel. 2. The method according to claim 1, which monitors whether or not a marker gas leaks by detecting a change in pressure in a closed space. 3 Claims 1 or 2 which monitor whether or not a marker gas has leaked into the reactor using a marker gas detection mechanism provided in the upper cover gas space in the reactor vessel or primary cooling system equipment. The method described in section. 4 Claims 1, 2, or 3 which monitor whether or not a marker gas leaks from the guard vessel using a marker gas detection mechanism provided in a space outside the guard vessel.
The method described in section. 5 The pressure of the marker gas sealed in the sealed space is approximately 1
．． Claim 1, which is 5 to 3 atmospheres (absolute pressure);
The method according to paragraph 2, paragraph 3, or paragraph 4. 6 Claim 1 in which the marker gas is helium gas
The method according to paragraph 2, paragraph 3, paragraph 4, or paragraph 5. 7. The method according to claim 1, 2, 3, 4, 5, or 6, wherein the marker gas is a gas to which a stable isotope of a rare gas is added. 8. The method according to claim 3, 4, 5, 6, or 7, wherein a mass spectrometer linked to a gas sampling device is used as a detection mechanism for the marker gas. 9 Claim 1, in which the nuclear reactor is a fast breeder reactor,
The method according to paragraph 2, paragraph 3, paragraph 4, paragraph 5, paragraph 6, paragraph 7, or paragraph 8.