JPS5810679A - Upper core mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of the upper structure inside the reactor of a tank-type fast breeder reactor (tank-type FBR). The present invention relates to a support structure for a core upper structure that is suitable when controlling core power fluctuations due to changes in the position of control rods becomes a problem.

The purpose of the present invention is to prevent rapid fluctuations in core output due to fluctuations in the position of control rods in the core caused by relative displacement between the roof slab and the core due to vertical vibrations during an earthquake with large vertical motions, and to facilitate power control. The objective is to provide a support structure for the control rods.

The control rod device of the tank-type FBH, which consists of control rods, guide tubes, and drive devices, is supported on the roof slab via the core superstructure (UIS) and rotating plug, while the core is supported via the core support structure. Since the control rods are supported by the main vessel, relative vertical displacement occurs between the control rods and the reactor core. The present invention aims to eliminate vertical relative displacement between the control rods and the reactor core by directly mounting the UIS, which directly supports the control rod device, on the core barrel at the upper part of the reactor core.

Figures 1a and 1b show a typical core structure.

Reference numeral 1 denotes a roof slab serving as a lid for a reactor vessel (not shown) of a nuclear reactor, which is a large disk-shaped structure with a diameter of ~20 m and a weight of approximately 5,000 tons, and is relatively easy to vibrate and move in the vertical direction. In the center of the roof slab 1, a rotary plug 2 is supported by the roof slab. The control rod guide tube 7 is fixed to the rotating plug 2 together with the control rod drive device (CHD) 9, and hangs downward to several tens of inches above the core barrel 6, and is supported halfway by the vibration isolating plate of the UIS 4. has been done.

UIS4 has a cylindrical structure, and its upper end is connected to the rotating plug 2.
It is fixed to the bottom plate of the UIS with bolts, etc., and its lower end connects several seismic keys 5 fixed to the UIS to the keyway 12 of the core barrel 6 at the top of the core, with a gap in order to absorb vertical relative displacement between the UIS and the core barrel. are provided and fitted to prevent the UIS 4 from shaking in the horizontal direction.

A CRD housing 10 is fixed to the upper surface of the rotating plug to prevent the CRD from swaying laterally. When rotating the rotary plug 2, lift the TJ I S 4 together with the rotary plug 2 using the jack 11 that is based on the half slab 1, pull out the seismic key 5 through the keyway 12 of the core barrel 6, and then rotate it. let

FIG. 1 is a detailed view of section A in FIG. 1a.

An embodiment of the present invention will be described below with reference to FIGS. 2a and 2b.

The control rod drive device 9, the control rod guide tube 7, and the control rod 17 are
It is fixed and supported by a cylindrical in-furnace upper structure (UIS) 4. During operation, the UIS 4 is fitted into the seismic apparel 6 by the seismic key 5, and its own weight is absorbed by the core barrel 6.
, the upper part of which is supported against lateral loads by a slide bearing 16 in the rotating plug 2,
In addition, the UIS 4 and the rotary plug 2 are connected by a bellows 18, forming a pressure boundary in the furnace, and the UIS
4 is a rotating plug 2 and a roof slab 1 that supports it;
It is expressed as a structure that can be displaced vertically relative to the The jack 11 connecting the UIS 4 and the rotating plug 2 is
This is for jacking up the UIS 4 in order to pull out the earthquake-resistant key 5 of the UIS 4 from the core barrel 6 during fuel exchange.

FIG. 2 is a detailed view of section A in FIG. 2a.

According to the present invention, since the UIS 4 that supports the control rods 17 is supported by the core barrel, in principle, relative displacement between the control rods 17 and the reactor core does not occur, and sudden fluctuations in the reactor core power can be prevented.

[Brief explanation of the drawing]

FIGS. 1a and 1b are overall vertical sectional views showing a general core structure, and FIG. 2 is an overall vertical sectional view showing the reactor core structure of the present invention. 4...UIS, 7...Control rod guide tube, 9...Control rod drive device, 5...Earthquake resistant key, 6...Core barrel. Agent Patent Attorney Akio Takahashi

Claims (1)

[Claims] 1. In a fast breeder reactor, the control rod drive device, control rod guide tube, and core upper structure that supports the control rods are connected and supported by the core barrel of the reactor core, supporting vertical and horizontal loads, and
A core upper structure characterized in that a rotating plug penetration part has a sliding structure that supports horizontal loads and allows vertical displacement.