JPS59155681A - Control method of valve associated with accumulator - Google Patents

Abstract

PURPOSE:To prevent water hummer at the downstream upon opening of scrum valve by measuring pressure across valve while controlling accumulator pressure through gas feed system such that the differential pressure will be constant. CONSTITUTION:Pressures at the upper and downstream sides of scrum valve 2 are measured by pressure gauges while pressure of accumulator 1 is cntrolled through gas feed system 5. In such system, when the pressure at the downstream of scrum valve 2 will drop below normal level while pressure across scrum valve 2 will increase, pressure of accumulator 1 can be decreassed through gas feed system 5 thus to prevent water hummer at the downstream of scrum valve 2.

Description

[Detailed Description of the Invention] [Original Field of the Invention] The invention relates to a piping system that disables pressure accumulators and normally closed valves, particularly in the piping system when the scram valve of a boiling water reactor suddenly opens. This is related to i-dynamic leveling.

[Prior art]

A conventional control rod drive system has a scram insertion system consisting of a pressure accumulator and a normally closed scram valve. In the event of an abnormality in the atomic system or door, the scram pilot valve is switched to remove the gas pressure applied to the scram valve and quickly open the scram valve.

In the conventional example, the pressure of the pressure accumulator was constant, and the opening time of the scram valve was also set to be constant.

For this reason, if the scram valve is suddenly opened when the pressure on the downstream side of the scram valve is low and the differential pressure across the valve is large, the pressure in the high pressure accumulator may propagate downstream as a water hammer wave.

[Purpose of the invention]

An object of the present invention is to provide a method for preventing water hammer waves generated on the downstream side of the scram valve 2 when it is opened, and a device most suitable for carrying out the method.

[Summary of the invention]

In the present invention, there are cases where the pressure before and after the scram valve 20 is large depending on the operating state of the reactor, and in such a case, when a reactor scram is required and the scram valve is suddenly opened, a water hammer wave is generated due to the pressure difference. Therefore, as a means to eliminate the water hammer wave, it is possible to achieve this by controlling the pressure in the pressure accumulator5 or by increasing the opening time of the scram valve.

[Implementation sequence of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. The system is such that the pressure can be controlled by the gas supply system 5.

The control of this system is such that, for example, when the pressure on the downstream side of the scram valve 2 decreases compared to normal operation and the differential pressure across the scram valve 2 increases, the pressure in the pressure regulator 1 is increased by the gas supply system 5. The pressure difference is controlled so that the differential pressure across the scram valve 2 is within a certain value or at a constant value, as shown in FIG.

Thereby, even when the scram valve 2 is suddenly opened, excessive water hammer on the downstream side of the scram valve 2 can be completely prevented.

Incidentally, the reactor scram needs to be performed within a predetermined time, but this can also be achieved by setting the differential pressure across the scram valve 2 to be equal to or slightly larger than the differential pressure during rated operation.

FIG. 3 shows another embodiment of the invention. In this embodiment, the stem 6 of the scram valve 2 is opened and closed in relation to the spring 7 and the gas pressure 8 so that the opening speed of the scram-1P2 can be switched in two stages or in multiple stages. A pilot valve 9 is installed to supply/exhaust the gas 8 of the scram valve 2 from two locations.

When the differential pressure across the scram valve 2 is relatively small, gas 8 is supplied to the spring 7 side of the valve seat, and gas 8 on the opposite side of the spring 7 is exhausted so as to open the scram valve 2 quickly. .

When the differential pressure across the scram valve 2 is large, the gas 8 on the opposite side of the spring 7 is exhausted, but the gas 8 on the spring 7 side is kept sealed so that the scram valve 2 opens slowly.

In this way, the valve opening speed can be changed by the differential pressure across the scram valve 2, and excessive water hammer can be prevented from occurring.Figure 4 shows the valve opening time and water hammer mitigation rate. It can be seen that water hammer waves can be sufficiently alleviated by changing the valve opening time by a factor of about 2 to 3 times.

〔Effect of the invention〕

According to the present invention, it is possible to effectively reduce or prevent water hammer waves that may occur during reactor scram, and provide a safe and highly reliable nuclear reactor.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing one embodiment of the present invention, Fig. 2 is a line diagram showing the effects of the present invention, Fig. 3 is a configuration diagram showing another embodiment of the present invention, and Fig. 4 is a diagram showing the present invention. It is a -F diagram showing the effect of 1... pressure accumulator, 2... scram valve, 3... scram pilot valve, 4... pressure gauge, 5... gas supply system, 6... ... Valve stem, 7... Spring, 8... Gas, 9
...Pilot valve. I T Sengu Rinp (currently Gaijin) No. 3m (Q)

Claims (1)

[Claims] 1. A pressure accumulator characterized by measuring the pressure before and after the valve in a piping system having a normally closed valve and a pressure accumulator, and controlling the pressure in the pressure accumulator using a gas supply system so that the differential pressure remains constant. How to control Tsukisho.