JPH0351795A - Upper core structure of fast breeder reactor - Google Patents

Abstract

PURPOSE:To improve safety and reliability of an nuclear reactor by providing a receiving part at an outer circumferential surface of a jointed barrel and by providing a hooking part engaging with the receiving part on a thermal shield plate. CONSTITUTION:A receiving part 8 of a cross sectional shape of L of which upper part opens upwardly, is provided at an outer circumferential surface of a jointed barrel 2. On the other hand, a hooking part 9 of a cross sectional shape of L of which lower part opens downwardly, is provided at an upper inner part of a thermal shield plate 5 so as to be engaged with the aforementioned receiving part. With this structure, the thermal shield plate 5 can be fastened to the jointed barrel 2 by engaging the hooking part 9 with the receiving part 8 which is provided at the outer circumferential surface of the jointed barrel 2, and by fitting a stopper ring 10 between a holding part 11 and the hooking part 8. Consequently, the thermal shield plate 5 can be attached to the outer surface of the jointed barrel 2 without using stud bolts which is liable to become loose, and therefore safety and reliability of a nuclear reactor can be much improved.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to the upper core mechanism of a fast breeder reactor, and in particular, to prevent thermal stress caused by rapid temperature changes and temperature fluctuations of the coolant. The present invention relates to a mounting structure for a heat shield plate for protecting a torso.

(Prior Art) In general, the upper core mechanism of a fast breeder reactor consists of a joint shell 2 that is vertically installed on the lower surface of a shielding plug 1 that closes the upper opening of a reactor vessel (not shown), as shown in FIG. It is constructed by housing a control rod guide tube 3, an instrumentation well 4, etc. inside, and the outer periphery of the joint shell 2 protects the joint shell 2 from thermal stress caused by sudden temperature changes and temperature fluctuations of the coolant. A heat shielding plate 5 is provided with a gap therebetween.

Conventionally, the heat shielding plate 5 of such an upper core mechanism has a large number of stud bolts on the outer peripheral surface of the joint shell 2, as shown in FIG. 6, in order to prevent fluid vibrations caused by the flow of coolant. 6 was implanted by welding or screwing, and the mounting number was attached to the outer periphery of the joint body 2 using these stud bolts 6 and nuts 7.

(Problem to be Solved by the Invention) However, according to such a mounting structure, the stud bolts 6 installed on the outer peripheral surface of the joint body 2 are exposed to excessive heat caused by the coolant, fluid vibration, and furthermore, the heat shielding plate 5 These loads cause the stud bolts 6 to fatigue, and in the unlikely event that they break and fall into the reactor vessel, loose parts may be removed by the flow of coolant. There was a possibility that

The present invention was made in view of the above circumstances, and provides a core upper mechanism of a fast breeder reactor in which a heat shield plate can be attached to the outer periphery of a joint shell without using stud bolts that may become loose bolts. The purpose is to

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a heat shield on the outer periphery of a joint shell vertically installed on the lower surface of a shield plug that closes the upper opening of a reactor vessel. In the upper core mechanism of a fast breeder reactor having a plate, a receiving portion is provided on the outer peripheral surface of the joint shell, a hook portion that engages with the receiving portion is provided on the heat shielding plate, and the bone is provided above the portion. A presser portion is provided for fixing the hook portion to the bone portion via a retaining ring.

(Function) In the present invention, the hook part is engaged with the receiving part, and a retaining ring is installed between the presser part provided above the receiving part and the catching part, so that the hanging part can be attached to the receiving part. Because it can be fixed,
The heat shield plate can be attached to the outer periphery of the joint shell without using stud bolts that may become loose parts.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIGS. 1 to 3 show an embodiment of the present invention, in which a receiving portion 8 having an open upper part and a cross-section shaped like a letter L is provided on the outer circumferential surface of the joint body 2. As shown in FIGS. On the other hand, on the upper part of the inner surface of the heat shielding plate 5, there is provided a hooking part 9 which is open at the bottom and has an L-shaped cross section, and is adapted to engage with the receiving part 8. Also,
A presser portion 11 is provided above the bone portion 8 for fixing the hook portion 9 to the receiving portion 8 via a retaining ring 10.

According to such a structure, the hook part 9 is engaged with the receiving part 8 provided on the outer peripheral surface of the joint body 2, and the holding part 11 and the hook part 8 are connected to each other.
The heat shielding plate 5 can be fixed to the joint shell 2 by fitting the retaining ring 10 between them.

Therefore, in this embodiment, the heat shield plate 5 can be attached to the outer periphery of the joint shell 2 without using stud bolts that may become loose, and the safety and reliability of the reactor can be improved. .

Note that the present invention is not limited to the above embodiments,
For example, as shown in FIGS. 4 and 5, a receiving part 8 is provided on the lower outer periphery of the joint shell 2, and guide rails 12 are provided at four locations in the circumferential direction of the joint shell 2, and between these guide rails 12. The heat shielding plate 5 may be attached to the outer periphery of the joint shell 2 by incorporating a quarter-split heat shielding plate 5a.

[Effects of the Invention] As explained above, the present invention provides an upper core mechanism of a fast breeder reactor having a heat shield plate on the outer periphery of a joint body vertically installed on the lower surface of a shield plug that closes an upper opening of a reactor vessel. , a receiving part is provided on the outer circumferential surface of the joint body, and a hooking part that engages with the receiving part is provided on the heat shielding plate, and the hooking part is provided above the bone part to prevent it from coming off from the bone part. It is provided with a holding part that is fixed via a ring.

Therefore, the heat shield plate can be attached to the outer periphery of the joint shell without using stud bolts, and the safety and reliability of the nuclear reactor can be improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the upper core mechanism of a fast breeder reactor showing an embodiment of the present invention, Fig. 2 is a detailed view of section A shown in Fig. 1, and Fig. 3 is a detailed view of section B shown in Fig. 1. 4 is a sectional view of the upper core mechanism of a fast breeder reactor showing another embodiment of the present invention, FIG. 5 is a sectional view taken along line C-C in FIG. 4, and FIG. FIG. 2 is a cross-sectional view of the upper core mechanism of a fast breeder reactor. DESCRIPTION OF SYMBOLS 1... Shield plug, 2... Joint shell, 3... Control rod guide tube, 4... Instrumentation well, 5... Heat shield plate, 8...
- Receiving part, 9... Hooking part, 10... Retaining ring, 11... Holding part.

Claims (1)

[Claims] In a core upper mechanism of a fast breeder reactor having a heat shield plate on the outer periphery of a joint shell vertically installed on the lower surface of a shielding plug that closes an upper opening of a reactor vessel, a receiving part is provided on the outer peripheral surface of the joint shell, and A hook portion that engages with the receiving portion is provided on the heat shielding plate, and a presser portion is provided above the receiving portion for fixing the hook portion to the receiving portion via a retaining ring. Upper core mechanism of fast breeder reactor.