JPS58146894A - Exposure redusing system at main steam pipe rupture accident - 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 treatment of radioactive materials in water vapor and blowdown water released into the reactor building and turbines in the event of a main steam pipe rupture accident outside the containment vessel. This is a system that reduces the II dose received by operators staying indoors.

Figure 1 shows the conventional technology, and the nuclear reactor is great! 11
．． Turbine! 2. Containment vessel 4. Main steam tunnel room A1
Consists of main steam pipe l. Nuclear reactor 1 when main steam pipe 1 ruptures
And released into turbine aphrodisiac 2, #a! In order to prevent the internal pressure from rising, it is discharged into the atmosphere through the blowout panels 10 and 11 of each amotivation.

Therefore, in the event of a main steam pipe rupture accident outside the containment vessel 4, radioactive materials cannot be stored in the nuclear reactor [lNi11, I-hy[l[3].

In addition, in order to reduce exposure to radioactive materials taken in from the outside air intake port 13 in the event of an accident in the central control room 12, a recirculation system 14 and an iodine removal filter 9 have been installed to make the central control room 12 more economical. It becomes.

The object of the present invention is to provide a system for reducing released radioactivity that closes the opening after opening a blowout panel and processes it in an emergency gas treatment system in the event of a main steam pipe rupture accident outside the containment vessel;
The purpose of this project is to provide a system for reducing the exposure of nearby residents and operators in the central control room due to high-altitude emissions from the emergency gas treatment system exhaust stack and main exhaust stack.

In the present invention, the blowout panel part that is opened at the time of a main steam pipe rupture accident outside the containment vessel is made of 5# structure, and J11+
The radioactive materials released into the JL are released into the atmosphere from the main exhaust stack in the emergency gas treatment system exhaust stack.

As a result, it is possible to reduce the amount of radioactivity released, reduce the radiation exposure of nearby residents due to high-altitude releases, and significantly reduce the exposure of operators in the central control room near the release point due to high-altitude releases.

An embodiment of the present invention will be explained with reference to the drawings.

As shown in FIG. 2, the system of the present invention adds a shutter 15 that covers the ref.&R blowout panel portion to the blowout panel structure 10.11 of the reactor building and turbine building in the conventional system. It consists of an emergency gas treatment system exhaust stack 16 and a main exhaust stack 20, which release radioactive materials present in the room into the atmosphere.

The pressure in the main steam tunnel 3 increases due to the blowdown water and steam released by the rupture of the main steam pipe 1. In order to reduce this pressure rise, it is discharged to the reactor building Jll and the turbine building Ji12, and the blowout panels 10 and 11 of each building are opened to prevent pressure inside the building. After opening, the pressure inside the building is relieved, so the shutter 15, which was previously installed at the upper end of the blowout opening, is closed. At this time, the emergency gas treatment system 16 and the turbine ventilation system 1
Since the AM internal pressure will not rise due to ventilation at 7, no problem will occur even if the building is isolated after the initial building pressure rises.

In the emergency gas treatment system, the iodine is removed by the iodine removal filter 9 and then released into the atmosphere through the emergency gas treatment system exhaust stack 16.

On the other hand, radioactive substances existing in the turbine building can be released into the atmosphere through the turbine building ventilation system 17 and the main exhaust window 20.

According to the present invention, there are the following effects.

In the current safety assessment in the event of a main steam pipe rupture accident, the following two processes are considered for the amount of radiation received.

(1) Exposure due to blowdown water and steam released from the blowout panel opening before closing the main steam isolation valve (2) Blowout of steam leaking from the valve after closing the main steam isolation valve Radiation exposure due to radiation released from the panel to the environment In general, the amount of aSS received in a hypothetical accident in safety evaluation is that the dose in (2) above is 2 to 3 times the dose in (1).

According to the present invention, the exposure dose due to (2) above can be reduced as follows.

(2) The iodine removal filter in the emergency gas treatment system can reduce the amount of iodine released to about 1/10 to 1/20.

■When released from the high places of the emergency gas treatment system exhaust stack and the main exhaust stack, as shown in Figure 31 and Figure 4, compared to conventional ground release (release from the building blowout), the entire body is released at the site boundary. The amount of iodine exposed to the thyroid can be reduced to approximately 115%, and the thyroid radiation exposure due to iodine can be reduced to approximately 1/10.

■If the emergency gas treatment system exhaust stack or main exhaust stack is released from a high place, the concentration at a relatively short distance from the release point (for example, the central control room ventilation system intake) will be lower than the ground level, as shown in Figure 5. This is negligible compared to that during dissipation.

Therefore, the exposure dose due to this is negligible.

As a result, the processing capacity of the iodine removal filter in the emergency ventilation system of the central control unit can be significantly reduced.

As a result of the above, according to the present invention, the exposure due to the released radioactivity after the main steam isolation valve is closed can be reduced to a negligible level compared to the exposure due to the released radioactivity before the main steam isolation valve is closed. Therefore, according to the present invention, compared to the conventional coating amount, the amount of coating is about 1/3 to about 1/
It can be reduced to 4.

Furthermore, as another effect, the emission amount can be continuously monitored by the emergency gas treatment system radiation monitor 18 and the main exhaust stack monitor 19.

Another modification is shown in FIG. According to this variant! Ia indoor positive internal pressure prevention shutter 21 can reduce the internal pressure in the event that the building internal pressure increases.

[Brief explanation of drawings]

Figure 1(a) is an explanatory diagram of the conventional example, Figure 1(b) is a detailed diagram of part A, Figure 2(a) is a detailed diagram of the present invention, and Figure 2(b)
) is a detailed view of part B, Figure 3 is a relationship diagram between emission point height and whole body exposure dose, Figure 4 is a relationship diagram between emission point height and thyroid exposure dose, and Figure 5 is a relationship diagram between emission point height and evaluation point distance. The relationship diagrams of radioactivity concentration, FIGS. 6(a) and 6(b) are explanatory diagrams of other embodiments of the present invention. 1... Nuclear reactor charm, 2... Turbine building, 3...
Main steam tunnel presentation, 4... Containment vessel, 5... Main steam pipe, 6... Blowout panel, 7... Turbine,
8... Condenser, 9... Accumulative removal filter, 10.
...Reactor building blowout panel, 11...Turbine mat blowout panel, 12...Main control room,
13... Central control room chivalry system outside air intake, 14... Central 111! Omuro emergency recirculation thread, 15...Blowout panel opening closing shutter, 16...Emergency gas treatment system exhaust stack, 17...Turbine ventilation system, 18.
・・Emergency gas treatment system radiation monitor, 19...Main exhaust stack radiation monitor, 20 糟3Fig. N'fJ, 5'' There is no need for books.

Claims (1)

[Claims] 1. The blowout panels installed in Atomic PIa Otori and Turbine AM have a structure that can be closed after opening in the event of a main steam pipe rupture accident, reducing the release of radioactive materials from the blowout panel opening. ,l! This is a radiation exposure reduction system in the event of a main steam pipe rupture accident, which is designed to reduce the radiation exposure of Chianbe residents and center operators.