JPH03122593A - Tank type fast bredder reactor - Google Patents

Abstract

PURPOSE:To enable treatment of a leak flow at a discharge side of a main circulation pump by providing an outer cylinder outside the main circulation pump and, at the same time, by providing a small hole in a vicinity of a suction side of the main circulation pump. CONSTITUTION:Surrounding a main circulation pump 3, piping joints 7 and in-core pipings 6, an outer cylinder 15 of which bottom end is fastened to a reactor core support structure 5, si provided. A to end of the outer cylinder 15 is connected to an outer barrel of an inetermediate heat exchanger 2 through seal bellows 16. In this case, a leak flow from a connection part of the main circulation pump 3 and the picking joints 7, flows out into the outer cylinder 15, however, as a coolant is sucked out from a small hole 17 provided at a suction side of the main circulation pump 3. no coolant flows out to an outside of the outer cylinder 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention particularly relates to a tank-type fast breeder reactor with improved reactor vessel internal structure.

(Prior art) As shown in Fig. 2, a tank-type high-speed pump is designed to reduce size and simplify the design by combining an intermediate heat exchanger 2 provided inside a reactor vessel 1 and a main circulation pump 3 using an electromagnetic pump. A breeder reactor has been proposed.

That is, a primary coolant 11 is accommodated in the reactor vessel 1, and the upper opening of the reactor vessel 1 is closed by the loop slab 10. A reactor core 4 composed of a plurality of fuel assemblies (not shown), control rods (not shown), etc. is provided inside the reactor vessel 1, and this reactor core 4 is supported by a core support structure 9. .

Further, an intermediate heat exchanger 2 for exchanging heat between a primary coolant and a secondary coolant is supported on the loop slab 10, and a main circulation pump 3 composed of an electromagnetic pump is located below the intermediate heat exchanger 2. are combined, and the discharge side thereof allows coolant 11 to be sent into the reactor core 4 via a piping joint 7 and an in-furnace piping 6.

Furthermore, the coolant storage space within the reactor vessel 1 is divided into an upper plenum 12, a lower plenum 13, and an intermediate plenum 14 by the upper partition wall 8 and the core support structure 5.

(Problems to be Solved by the Invention) In the tank type fast breeder reactor proposed in Fig. 2, the main circulation pump 3 combined with the intermediate heat exchanger 2 is pulled out of the reactor from the viewpoint of maintenance and repair. I need to take it out. Therefore,
The lower part of the main circulation pump 3 and the joint part of the piping joint 7 have to have a fitting structure, and since this part is under high pressure of several kg/crl on the discharge side of the main circulation pump 3, the pressure is about 1 to 2%. There is a leak flow of (pump flow rate). This leakage flow is not negligible for the coolant volume of the intermediate plenum 14, and is large enough to completely replace the coolant in the intermediate plenum 14 within about one hour at rated conditions. Therefore, the intermediate plenum 14 is filled with a low-temperature coolant that has been cooled by exchanging heat with the secondary coolant in the intermediate heat exchanger. Upper plenum 12, in which the resulting high temperature coolant is contained. This will damage the structural integrity of the upper partition wall 8 that partitions the space. In addition, the reactor vessel 1 near the boundary between the upper plenum 12 and the intermediate plenum 14
and the core barrel (a part of the core support structure located on the side of the core), resulting in a large axial temperature distribution, impairing their structural integrity. Furthermore, the low-temperature coolant flowing from the intermediate plenum 14 to the upper plenum 12 causes temperature fluctuations in the vicinity of the outflow section, which may impair the structural integrity of the corresponding section.

The present invention was made in order to solve the above problems, and it treats the leak flow from the joint between the main circulation pump 3 and the pipe joint 7, and uses the coolant in a state where there is no flow (stagnant) in the intermediate plenum 14. An object of the present invention is to provide a tank-type fast breeder reactor in which temperature stratification of a secondary coolant is produced in an intermediate plenum to ensure structural integrity of a reactor vessel, etc.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a reactor vessel that houses a coolant and has an upper opening closed with a loop slab, and a reactor vessel that houses a coolant and has an upper opening closed with a loop slab. A reactor core heated by reaction heat, a core support structure that supports the core, a primary coolant inside the reactor vessel that is provided through the loop slab, and a secondary cooling that circulates outside the reactor vessel. an intermediate exchanger that exchanges heat with the reactor; a main circulation pump that is installed at the bottom of the intermediate heat exchanger and that sends coolant into the reactor core through the reactor piping; and a main circulation pump that is installed inside the reactor vessel that In a tank-type fast breeder reactor consisting of a partition wall that partitions a coolant storage space in a reactor vessel, an outer cylinder is provided on the outside of the main circulation pump, and a small hole is provided near the suction part of the main circulation pump. It is characterized by

(Function) Coolant leaking from the main circulation pump and piping joints does not flow outside the outer cylinder. Therefore, the coolant in the intermediate plenum becomes a stagnant coolant, resulting in temperature stratification of the coolant within the intermediate plenum.

As a result, it is effective in solving problems regarding the structural integrity of the reactor, core tank, and upper bulkhead. In addition, leakage flow from the joint between the main circulation pump and the piping joint flows into the outer cylinder, but since the coolant is sucked through the small hole provided on the main circulation pump suction side, the coolant does not flow out of the outer cylinder. It disappears. As a result, since there is no leakage flow, the coolant does not flow from the intermediate plenum to the upper plenum, and temperature fluctuations do not occur.

(Example) An example of a tank-type fast breeder reactor according to the present invention will be described with reference to FIG.

In FIG. 1, inside the reactor vessel 1 there is a lower intermediate heat exchanger 2. A near live circulation pump 3 is disposed and is supported by a core support structure 5 via an in-core piping 6 outside the reactor core 4 . A piping joint 7 is connected to the furnace piping 6. An upper partition wall 8 is provided along the upper inner wall surface of the reactor vessel 1 from the upper part of the reactor core 4 . A core upper mechanism 9 is provided extending from the top of the core 4 through the loop slab 10 . Inside the reactor vessel 1 is a coolant 1 that cools the reaction heat from the reactor core 4.
1 is housed therein, and the upper part forms an upper plenum 12, the lower part forms a lower plenum 13, and the central part forms an intermediate plenum 14, respectively. An outer cylinder 15 whose lower end is fixed to the core support structure 5 is provided to surround the main circulation pump 3, the piping joint 7, and the in-reactor piping 6. This outer cylinder 1
The upper end of 5 is connected to the intermediate heat exchanger 2 via a seal bellows 16.
is connected to the outer body of the A large number of small holes 17 are formed in the upper wall surface of the outer cylinder 15, and these small holes 17 are located near the suction side of the main circulation pump 3.

According to the above embodiment, leakage flow from the joint between the main circulation pump 3 and the piping joint 7 flows into the outer cylinder 15, but the coolant flows through the small hole 17 provided on the suction side of the main circulation pump 3. Since the coolant is sucked in, the coolant does not flow out to the outside of the outer cylinder 15.

Although FIG. 1 shows an example of a structure in which the reactor core 4 is supported from the bottom of the reactor vessel 1, the same method can be applied to other support methods, such as a structure in which the core is supported from the side of the reactor vessel. The structure allows leakage flow on the discharge side of the main circulation pump to be treated.

[Effects of the Invention] According to the present invention, the leak flow on the discharge side of the main circulation pump can be treated, and temperature stratification of the coolant is created in the intermediate plenum, and damage to the reactor vessel, core tank, upper bulkhead, etc. Issues regarding the structural integrity of the relevant section can be resolved.

It is also effective for cooling the coil of the electromagnetic pump as a by-product of collecting glue in the outer cylinder 15.

[Brief explanation of drawings]

Figure 1 is an elevational view schematically showing an embodiment of a tank-type fast breeder reactor according to the present invention, and Figure 2 is an intermediate heat exchanger and main circulation pump proposed for this type of tank-type fast breeder reactor. 1 is an elevational view schematically showing a tank-type fast breeder reactor in which the 1...Reactor vessel 2...Intermediate heat exchanger 3...Main circulation pump 4...Reactor core 5...Core support structure 6...In-reactor piping 7...Piping joint 8 ...Upper bulkhead 9...Upper core mechanism 0...Loop slab...Coolant 2...Upper plenum 3...Lower plenum 4...Intermediate plenum 5...Outer cylinder 6...Seal Bellows 7...Koko (8733) Agent Patent attorney Yoshiaki Inomata (and others)
1 person) Difference 1 circle

Claims (1)

[Claims] A reactor vessel that houses a coolant and has an upper opening closed with a loop slab, a reactor core that heats the cooling section provided in the reactor vessel with nuclear reaction heat, and a core support structure that supports this core. and an intermediate heat exchanger that is provided through the loop slab and performs heat exchange between the primary coolant inside the reactor vessel and the secondary coolant circulating outside the reactor vessel;
A main circulation pump is provided at the lower part of the intermediate heat exchanger and feeds coolant into the reactor core via the in-reactor piping, and a main circulation pump is provided inside the reactor vessel and partitions a coolant storage space within the reactor vessel. A tank type fast breeder reactor comprising a partition wall, characterized in that an outer cylinder is provided outside the main circulation pump, and a small hole is provided near the suction part of the main circulation pump.