JPH04216492A - Reactor for deep sea surveying ship - Google Patents

Abstract

PURPOSE:To provide a reactor suitable for a power source of a deep sea surveying ship which has superior anti-pressure performance and avoid water quality control by containing all structure parts in an anti-pressure shell without projection and eliminating the use of light water in the reactor body. CONSTITUTION:In an anti-pressure shell 1 of leak tight cylinder shape, provided are a reactor body 2 consisting of a high temperature fast reactor or a high temperature gas reactor, a heat exchanger 3, a turbine 4, a generator 5 driven by the turbine, a compressor 6 and a gas cooler 8 placed along the inner surface of the anti-pressure shell and using the inner surface of the anti-pressure shell as the heat transfer surface. The primary coolant of the reactor body is circulated between the reactor body and the heat exchanger. The secondary system gas coolant is circulated from the heat exchanger, turbine, gas cooler, compressor to the heat exchanger. This power generation system is a closed Braiton cycle using the secondary gas coolant as a working fluid.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is suitable as a power source for a deep-sea research vessel for diving into the deep sea and conducting various surveys.
In particular, it relates to nuclear reactors with excellent pressure resistance.

0002

2. Description of the Related Art Although this type of nuclear reactor for deep-sea research vessels has not yet been put into practical use, several proposals have been made regarding its structure. One example is a light water reactor such as a PWR or BWR, in which the reactor body, steam generator, turbine, generator, condenser cooler, etc. are placed inside a cylindrical pressure shell, and the pressure shell is submerged in seawater. A nuclear reactor for deep-sea research vessels has been proposed with a structure that allows
Atsushi Sako et al., “Design study of deep sea reactor DSR (1) Reactor plant concept”, Atomic Energy Society of Japan “1990 Annual Meeting” (19
April 2-4, 1990, University of Tokyo) Proceedings, 180
(see page).

0003

[Problems to be Solved by the Invention] However, in the above-mentioned nuclear reactor structures that have been proposed in the past, the condenser and heat pipe type cooler are disposed outside the pressure shell.
It has a structure in which it is connected by piping that penetrates the pressure shell and extends to the outside. There is a question as to whether such a structure in which the piping is extended outside the pressure shell will necessarily provide satisfactory pressure resistance under water pressure of about 650 atm in deep sea, for example at a depth of 6500 m.

Furthermore, when a light water reactor is used as the reactor main body, the impurity concentration of the primary cooling water and feed water must be kept below standard values, especially if the reactor is not operated for a long period of time in deep sea. Water quality management of the primary cooling water is an issue for a nuclear reactor for a deep-sea research vessel.
Handling becomes complicated.

[0005] Therefore, the present invention can further improve pressure resistance against deep sea pressure without using a cooler or condenser that must be installed outside the pressure shell via piping, etc. The purpose was to provide an improved nuclear reactor for deep-sea research vessels that does not require water quality control.

[0006]

[Means for Solving the Problems] That is, the nuclear reactor for a deep-sea research vessel of the present invention includes a reactor body consisting of a high-temperature fast reactor or a high-temperature gas reactor, a heat exchanger for circulating the primary coolant from the reactor body, and a turbine. A generator driven by this turbine and a compressor that compresses the secondary gas coolant are arranged inside a closed cylindrical pressure shell submerged in seawater, and the inner surface of the pressure shell is used as a heat transfer surface. A secondary gas coolant in which a gas cooler is arranged along the inner surface of the pressure shell, and the secondary gas coolant is circulated through the heat exchanger, turbine, gas cooler, and compressor to the heat exchanger. It is characterized by having a circulation path.

[0007] Yes.

[Operation] The primary coolant heated to a high temperature in the reactor body is led to the heat exchanger and circulated back to the reactor body. on the other hand,
The gas flowing through the secondary gas coolant circuit is heated in a heat exchanger and then guided to a turbine to drive it. Power is generated by the turbine driving a generator. The high-temperature gas that exits the turbine then enters the gas cooler installed along the inner surface of the pressure shell, where the amount of heat transferred from the high-temperature gas to the inner surface of the pressure shell causes heat to flow through the relatively thick pressure shell. It is transferred to the outer surface of the pressure shell by conduction, and is further cooled by being removed into the surrounding seawater. The cooled and denser gas is led to the compressor, compressed, and circulated again to the heat exchanger.

As described above, in this invention, since the cooler for the secondary gas coolant is provided along the inner surface of the cylindrical pressure shell, the condenser and cooler are not disposed outside the pressure shell as in the conventional case. There is no need for a complicated structure in which the reactor is connected with piping that penetrates the pressure shell, and as a result, the pressure resistance of the reactor can be improved compared to conventional reactors.

[0009] In order for waste heat to be efficiently removed to seawater by heat conduction within the relatively thick pressure shell, the temperature difference between the inside and outside surfaces of the pressure shell must be at least 50°C or more, preferably close to 100°C. This is necessary. Therefore, in this invention, it is necessary to use a high-temperature fast reactor or a high-temperature gas reactor that can obtain a primary coolant temperature of approximately 700° C. at the reactor vessel outlet of the reactor body. Light water reactors and ordinary fast reactors whose primary coolant temperature at the exit of the reactor vessel is as low as about 550°C are unsuitable as the reactor body used in this invention. In addition, since the reactor body is capable of raising the primary coolant outlet temperature to nearly 700°C, it is possible to use a closed Brayton cycle or Stirling engine using a secondary gas coolant as the working fluid, as in the present invention.・The system can be used as a power generation system.

0010

[Embodiment] Fig. 1 illustrates the structure of a nuclear reactor for a deep-sea research vessel according to the present invention, and its external shape is characterized by the fact that there is no component that must be installed outside the cylindrical pressure shell 1. However, all the structural members are housed inside the pressure shell 1.

The pressure shell 1 can be made of a cylinder made of martensitic stainless steel or Ti alloy and has an elliptical longitudinal section, and its top opening is sealed with a removable lid 1a. A reactor main body 2 is installed in the lower part of the pressure shell 1, and a primary coolant circulation path A is formed between the reactor main body 2 and a heat exchanger 3 provided above. A turbine 4 , a generator 5 , and a compressor 6 are disposed in the upper part of the pressure shell 1 , and are connected to each other so that the generator 5 and the compressor 6 are driven by a rotating shaft 7 of the turbine 4 . Further, regarding the main part of the inner surface of the pressure shell 1, a sealed space is formed by arranging steel plates along this inner surface and at regular intervals from this inner surface, and this space functions as a gas cooler 8. . By attaching fins 8a inside the gas cooler 8 as necessary, the cooling effect can be improved. Then, by connecting each member with piping, a secondary gas coolant circulation path B of heat exchanger 3 → turbine 4 → gas cooler 8 → compressor 6 → heat exchanger 3 is created.
is formed.

Note that the gas flow path between the compressor 6 and the heat exchanger 3 in the secondary gas coolant circulation path B and the gas flow path between the turbine 4 and the gas cooler 8 are passed through for heat exchange. By providing the economizer 9, energy balance can be improved. Furthermore, by arranging the radiation shielding material 10 between the reactor body 2 and the heat exchanger 3, it is possible to prevent the turbine 4 and the like from deteriorating due to the influence of radiation. In addition, if the screw 11 is disposed in the seawater near the outside of the pressure shell 1 so that the seawater in contact with the outer surface of the pressure shell 1 constantly flows, it is possible to cool the gas cooler 8 using the pressure shell as a heat transfer surface. This is preferable because efficiency can be increased.

The operation of the nuclear reactor of the present invention will be explained with reference to FIG. 2, which clearly shows the primary coolant circulation path A and the secondary gas coolant circulation path B. The primary coolant that has reached a high temperature in the reactor body 2 is guided to the heat exchanger 3 through the circulation path A.
After exchanging heat with the secondary gas coolant, the reactor main body 2
It is circulated to As the primary coolant, liquid metals such as sodium or lithium are generally used in high-temperature fast reactors, and gases such as carbon dioxide, helium, and nitrogen are generally used in high-temperature gas reactors.

The secondary gas coolant heated to a high temperature by heat exchange in the heat exchanger 3 is led to the turbine 4 through the circulation path B to drive it, and then passes through the economizer 9 to the gas cooler 8. be introduced. In the gas cooler 8, the gas is cooled by heat being removed to the surrounding low-temperature seawater by heat conduction through the pressure shell 1. The cooled gas whose density has increased is taken out from the lower part of the gas cooler and guided to the compressor 6, where it is compressed and then sent to the economizer 9.
The gas is then sent to the heat exchanger 3 again, where it is converted into a high-temperature gas by heat exchange with the primary coolant. In the economizer 9, the relatively high temperature gas discharged from the turbine 4 warms the low temperature gas. As the secondary gas coolant, He or a mixed gas of He (60%) + Xe (40%) can be used.

[0015] When the pressure shell is relatively thick, for example about 10 cm, made of martensitic stainless steel, the temperature difference between the inner and outer surfaces of the pressure shell of the gas cooler needs to be close to 100°C. In this invention, by using a high-temperature fast reactor or a high-temperature gas reactor for the reactor body and by using a gas-based closed Brayton cycle for the power generation system, the temperature difference between the inside and outside surfaces of the pressure shell is made approximately 100°C. be able to. That is, for example, the temperature of the primary coolant at the outlet of the reactor vessel in a high-temperature fast reactor is approximately 700°C, and at this time, the average gas temperature during exhaust heat in a closed Brayton cycle using a secondary gas coolant is approximately 180°C.
℃. The temperature drop in the gas inside the gas cooler is 70℃
, the temperature difference between the pressure shell outer surface and the seawater in seawater is 5℃.
, assuming that the temperature of seawater is 5°C, the temperature difference ΔT between the inner and outer surfaces of the pressure shell can be calculated as follows. ΔT=180 −70−5−5=100 (° C.) Therefore, the required temperature difference between the inner and outer surfaces of the pressure shell can be provided, and sufficient cooling efficiency can be provided.

On the other hand, if a light water reactor is used as the reactor body, water will be used as the secondary coolant. In this case, if the gas cooler 8 as in the present invention is used, water vapor will condense on the inner surface of the pressure shell. Since the condensation temperature at this time is 35 to 45°C, the temperature difference ΔT between the inner and outer surfaces of the pressure shell
is ΔT=(35~45)-5-5=25~35 (℃)
, which is 1/4 of the value of ΔT in this invention described above.
It becomes ~1/3. This means that the heat transfer area of the cooler needs to be 4 to 3 times larger, and therefore the size of the pressure shell itself has to be 4 to 3 times larger, providing a small nuclear reactor for deep-sea research vessels. This becomes practically impossible.

[0017]

[Effects of the Invention] As can be seen from the above description, according to the nuclear reactor for deep sea research vessels of the present invention, a gas cooler is disposed along the inner surface of the pressure shell, and the reactor is a closed Brayton cycle in which gas is used as the working fluid. Since it is adopted as a power generation system, gas, which is the working fluid of the power generation system, can be efficiently cooled with a gas cooler, and there is no need to install a cooler or condenser outside the pressure shell via piping, etc. Therefore, it is possible to improve pressure resistance against deep sea water pressure.

Furthermore, since a high-temperature fast reactor or a high-temperature gas reactor is used as the reactor body instead of a light water reactor, there is no need to perform water quality control as in the case of using a light water reactor.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a preferred embodiment of a nuclear reactor for a deep-sea research vessel according to the present invention.

FIG. 2 is an explanatory diagram showing a primary coolant circulation path and a secondary gas coolant circulation path in the nuclear reactor of FIG. 1; 1...Pressure shell, 2...Reactor body, 3...Heat exchanger,
4... Turbine, 5... Generator, 6... Compressor, 8... Gas cooler, A... Primary coolant circulation path, B
...Secondary gas coolant circulation path.

Claims (3)

[Claims] Claims 1: A reactor body consisting of a high-temperature fast reactor or a high-temperature gas reactor, a heat exchanger for circulating primary coolant from the reactor body, a turbine, a generator driven by the turbine, and a secondary gas system. A compressor for compressing the coolant is disposed inside a closed cylindrical pressure shell submerged in seawater, and a gas cooler with the inner surface of the pressure shell as a heat transfer surface is disposed along the inner surface of the pressure shell, A deep sea system characterized by having a secondary gas coolant circulation path for circulating the secondary gas coolant through the heat exchanger, the turbine, the gas cooler, and the compressor to the heat exchanger. Research vessel nuclear reactor. 2. An economizer is disposed in the secondary gas coolant circulation path, gas from the compressor is passed through the economizer and then supplied to the heat exchanger, and gas from the turbine is passed through the economizer. 2. A nuclear reactor for a deep-sea research vessel according to claim 1, wherein the reactor is circulated to said gas cooler after being circulated to said gas cooler. 3. The nuclear reactor for a deep-sea research vessel according to claim 1, wherein a screw is disposed in seawater near the outside of the pressure shell.