JP2001242250A - Radiation monitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate the form of an accident at nuclear installations to provide accurate information for disaster preventive measures. SOLUTION: A radiation measuring device 2 consists of a neutron ray sensor 21, a gamma ray sensor 22, a radioactive dust measuring device 23, a radioactive iodine measuring device 24, and a data transmission device 25 to monitoring posts. An accident form judging device 11 judges the form of an accident by a logical judging device 300 upon receiving a signal from the radiation measuring device 2, and displays the judged result on a display output device 308. The fixed monitoring post 26 is a conventional radiation monitor previously installed around nuclear installations, while the portable monitoring post 27 is a radiation monitor temporarily placed in an appropriate place when necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disaster prevention manager of a local government or the like in which an accident occurs at a nuclear facility, which measures radiation surrounding the facility to understand the situation of the accident. The present invention relates to a radiation monitoring device intended to assist in making a proper decision.

[0002]

2. Description of the Related Art When radiation or radioactive material leaks from a nuclear facility, a facility for detecting the leak is a monitoring post disposed around the facility. However, conventional monitoring posts are mainly configured with equipment that assumes leakage of radioactive materials, and measures for disaster prevention managers around residents are mainly to seal houses and evacuate indoors. Any further action required the support of experts.

[0003]

[Problems to be Solved by the Invention] When an accident occurs in a nuclear facility, the form and scale of the accident and the impact on the surrounding environment must be promptly determined in order to take measures to minimize the impact on the surrounding area. It is necessary to understand precisely.

[0004] It is an object of the present invention to determine whether the type of accident is radiation leakage or radioactive material leakage, and a manager such as a disaster prevention center of a municipal government having a nuclear facility specializes in making an accurate judgment for disaster preventive measures. It is intended to help people make quick decisions without waiting for home support.

[0005]

In order to achieve the above-mentioned object, a radiation monitoring apparatus according to the present invention monitors a space radiation dose rate by adding a neutron beam measuring apparatus to a conventional gamma ray measuring apparatus as a measuring apparatus, and monitors the radiation rate. The concentration of radioactive substances in the air is monitored by a dust measuring device and a radioactive iodine measuring device. This is a radiation monitoring device equipped with an accident type determination device that determines the type of accident by receiving signals from these radiation measurement devices.When an accident occurs at a nuclear facility, the accident can be quickly detected without waiting for expert support. It is characterized by supporting the determination of the form and the determination of an appropriate disaster prevention guideline.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in Table 1 and FIG.
6 will be described with reference to FIG.

Table 1 shows the decision logic of the accident form decision apparatus 11 of the present invention based on information from the radiation measurement equipment.

[0008]

[Table 1]

If the neutron or gamma ray air dose rate measurement results show a significant value above the natural radiation level,
It can be determined that the radiation leaked. However, in the case of gamma rays, even when a large amount of radioactive material leaks, the level increases, so it is necessary to check the concentration of radioactive dust and radioactive iodine in the air. In the case of radiation leaks, apart from places with high radiation shielding capacity, such as reinforced concrete buildings and basements, ordinary houses have little value for indoor evacuation, and evacuation to a point away from the facility where the accident occurred is promptly performed. is necessary. If the neutron beam level rise is the main factor, it is expected that a large amount of radiation will be generated due to the reactivity injection accident at the nuclear reactor and the criticality accident at the nuclear fuel processing facility or reprocessing facility. However, in the case of a nuclear reactor, since the shielding of the facility has a sufficient capacity, there is little possibility of direct radiation leakage unless the accident involves damage to the facility.

When the gamma ray level rises mainly, the radiation source moves to an unexpected position in the irradiation facility using radioisotope or radiation leakage from a place with little shielding due to an unexpected beam orbit in the accelerator facility. It is assumed that a gamma ray leaks from a place where there is little. In the case of accelerator facilities, neutron radiation may also be generated depending on the type of accelerator, but usually sufficient shielding is provided.

The release of fission products from the reprocessing facility is:
This can occur in the event of a gas exhaust treatment facility failure. In this case, the radioactive dust concentration increases. Radioactive iodine is also likely to be detected. Because radioactive iodine is selectively incorporated into the thyroid line, it may be necessary to administer iodine tablets as one of the measures to prevent damage to local residents.
Depending on the concentration of the released radioactive material in the air, the level of gamma rays also increases. Even in a nuclear reactor, in a situation where the fuel cladding of the reactor core is damaged due to reactivity input or loss of coolant, fission products accumulated in the fuel are released. Nuclear reactors are also equipped with gas exhaust treatment facilities,
Further, since barriers such as a pressure vessel and a containment vessel are provided, fission products released from the fuel are not directly released to the atmosphere.

In the case of the release of nuclear fuel material from a nuclear fuel processing facility, the concentration of radioactive dust in the air exhibits a significant level increase. Although gamma rays from nuclear fuel materials such as uranium are smaller than gamma rays from fission products, any radioactive dust detector equipped with a beta ray detector can detect it with high sensitivity.

The release of radioisotopes from facilities using radioisotopes depends on the isotopes to be released, but generally, there are many isotopes that emit gamma rays and beta rays. Therefore, it is often detected by an increase in the level of radioactive dust. If the amount of radioisotopes released is high, gamma rays also show significant levels. The facilities that use radioisotopes also have gas waste treatment facilities.

When an accident involving radiation leakage becomes large-scale and mechanical damage occurs in a part of the facility, signs of both radiation leakage and radioactive material leakage are detected.

In the case of a radioactive substance leakage accident, the emitted radioactive substance is diffused downwind, so that anisotropy of the radioactive substance concentration in the air due to the wind direction is characteristic. On the other hand, in a radiation leak accident, there is no effect of wind. Observed radiation levels differ depending on whether there is any radiation shielding capability, such as terrain and structures, between the facility where the accident occurred and the radiation observation point.

As described above, by determining the type of the accident, whether radiation leakage or radioactive material leakage, based on the logic of Table 1, it is possible to determine whether necessary evacuation or immediate evacuation should be assisted by an expert. You can do it quickly without waiting.

FIG. 1 shows a functional configuration of a radiation monitoring apparatus 1 provided with an accident type judging apparatus 11 according to the present invention. The radiation measuring device 2 includes a neutron sensor 21, a gamma ray sensor 22, a radioactive dust measuring device 24, and a data transmission device 25 for monitoring posts. The accident type determination device 11 receives the signal from the radiation measurement device 2, determines the type of the accident by the logic determination circuit 300, and displays the determination result on the display output device 308. The fixed monitoring post 26 is a conventional radiation monitoring device installed in advance around a nuclear facility.
The portable monitoring post 27 is a radiation monitoring device that is temporarily placed in an appropriate place as needed. The meteorological observation device 3 is a facility for obtaining information for estimating the state of diffusion of radioactive substances released from a nuclear facility, and includes a wind direction sensor, a wind speed sensor, and the like. The position measuring equipment 4 is an equipment for ascertaining the current position of the radiation monitoring device 1 and uses a car navigation device. The video monitoring device 5 is a facility for visually capturing the surrounding situation such as the damage situation of the nuclear facility, the presence or absence of an injured person, the leakage situation of cooling water, steam, and the like when the accident occurs. It consists of a video camera and a floodlight for night monitoring. The communication terminal 6 is a communication means for communicating with the radiation monitoring apparatus 1 and the disaster prevention center 10 which controls the response to the accident, and is constituted by a telephone, a facsimile, a personal computer, and the like.

The communication equipment 7 is a communication means between the radiation monitoring apparatus 1 and the disaster prevention center 10 installed by the national or local government and uses satellite communication. The loudspeaker 8 and the display panel 9 are facilities for notifying nearby residents of the radiation level measured by the radiation monitoring device 1 in real time and supporting an accurate evacuation behavior. Such information is originally transmitted from the disaster prevention center 10, but has a public information function for the purpose of promptly providing information to nearby residents and gaining an understanding of radiation monitoring activities.

FIG. 2 shows a detailed configuration example of the accident form judging device 11. Neutron beam sensor 21, gamma ray sensor 22,
Outputs of the radioactive dust measuring device 23 and the radioactive iodine measuring device 24 are input to comparators 301 to 304, respectively. The comparator compares the natural radiation level with a reference value which is set with reference to the reference value.
05 and 306 are input. The logical decision unit 305 is the comparator 3
It operates by OR logic that outputs an output signal when a signal is received from one or both of 01 and 302. Similarly, the logic determiner 306 outputs a result determined by OR logic with respect to the outputs of the comparators 303 and 304. Logical decision unit 3
07 receives the output signals of the logic decision units 305 and 306 and
Operates with ND logic. That is, the logic decision unit 307 outputs an output signal when the logic decision units 305 and 306 output an output signal at the same time. The display output device 308 is provided for the logical decision unit 30.
Three types of determination results are displayed corresponding to the output signals of 5, 306 and 307. When the output signal of the logic decision unit 305 is received, the display “radiation leakage” is displayed. Similarly,
The display "radioactive substance leak" is displayed for the output signal of the logical judgment unit 306, and the display "large accident scale" is displayed for the output signal of the logical judgment unit 307.

FIG. 3 shows the configuration of the alarm device. The signal from the radiation measurement equipment 2 is compared with a reference signal 106 set in advance by a comparator 101, and if the signal exceeds a reference value, the amplifier 10
2 and 104. Amplifiers 102 and 104
Amplifies this signal and activates the audible alarm 103 and the optical alarm 105 to indicate that the vehicle has entered the radiation level alert zone. In this case, the signals from the radiation measurement equipment 2 use the signals from the neutron sensor 21 and the gamma ray sensor 22 that are easily monitored continuously.

When an alarm occurs, the signal levels of the neutron sensor 21 and the gamma ray sensor 22 are carefully checked, and at the same time, the radioactive dust measuring device 23 and the radioactive iodine measuring device 2 are checked.
4 is also operated to determine the type of accident and determine whether it is appropriate to approach the facility further.

FIG. 4 shows a facility configuration for real-time disclosure of data collected by the radiation monitoring apparatus 1 to nearby residents. The signal of the radiation measurement equipment 2 is stored in the memory 201. The voice synthesizer 202 converts the data in the memory 201 into a voice signal and inputs the voice signal to the amplifier 203. Amplifier 203
Drives the loudspeaker 204 to output information in the form of a voice such as "the current radiation level is 2 microsieverts per hour". On the other hand, the amplifier 205 amplifies the signal of the memory 201 and drives the display panel 206. The display panel 206 uses a method that can be visually recognized even in the daytime, such as an electric sign.
FIG. 5 shows an example of display on the display panel.

FIG. 6 shows a state where the loudspeaker 204 and the display panel 206 are mounted on an automobile 400 on which the radiation monitoring apparatus 1 is mounted. Two display panels 206 are installed back to back as needed to enhance visibility from the surroundings.

[0024]

As described above, according to the present invention, the following effects can be obtained by accurately determining the type of accident and estimating the scale of the accident in the event of an accident at a nuclear facility.

In the event of an accident at a nuclear facility, by judging whether the accident is a radiation leak or a radioactive substance leak, an administrator of a local government's disaster prevention center or the like having the facility can quickly proceed without waiting for expert support. Appropriate disaster prevention measures can be taken.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a radiation monitoring apparatus of the present invention.

FIG. 2 is a diagram illustrating an example of an accident type determination device provided in the radiation monitoring device.

FIG. 3 is a diagram illustrating an example of a radiation level warning device.

FIG. 4 is a diagram illustrating an example of a radiation level information device.

FIG. 5 is a diagram showing an example of display on a radiation level display panel.

FIG. 6 is a diagram showing an example in which a loudspeaker for public information and a display panel are mounted on an automobile.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Radiation monitoring device, 2 ... Radiation measurement equipment, 21 ... Neutron ray sensor, 22 ... Gamma ray sensor, 23 ... Radioactive dust measurement device, 24 ... Radioactive iodine measurement device, 25 ... Data transmission device, 26 ... Fixed monitoring post, 27 ... portable monitoring post, 3 ... meteorological observation equipment, 4 ... position measuring device, 5 ... video monitoring equipment, 6 ... communication terminal, 7 ... communication equipment, 8 ... loudspeaker, 9 ... display panel, 10 ... disaster prevention center, 1
DESCRIPTION OF SYMBOLS 1 ... Accident form determination apparatus, 201 ... Memory, 202 ... Speech synthesis apparatus, 203 ... Amplifier, 204 ... Loudspeaker, 205 ...
Amplifier, 206: display panel, 300: logic judgment circuit, 30
1 to 304: a comparator; 305, 306: a logical determiner of an OR operation; 307: a logical determiner of an AND operation; 308: a display output device;

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaaki Fujii 3-2-1 Sachimachi, Hitachi-shi, Ibaraki Hitachi Engineering Co., Ltd. (72) Katsuhiro Okusawa 3-2-2 Sachimachi, Hitachi-shi, Ibaraki No. 1 Hitachi Engineering Co., Ltd. (72) Inventor Kenji Sano 3-2-1 Kochicho, Hitachi City, Ibaraki Prefecture Inside Hitachi Engineering Co., Ltd. (72) Inventor Takio Mano 3-chome, Kochicho, Hitachi City, Ibaraki Prefecture No. 1-1 In the Nuclear Power Division of Hitachi, Ltd. (72) Inventor Toshihiko Onjin 3-2-2, Sachimachi, Hitachi-shi, Ibaraki F-term in Hitachi Engineering Services Co., Ltd. 2G088 EE10 EE11 EE12 FF04 FF09 KK24 KK29 MM02 MM05 MM09

Claims (1)

[Claims] 1. A radiation monitoring apparatus comprising a space dose rate measuring device and an airborne radioactive material concentration measuring device as a radiation measuring device, wherein the form of the accident is determined to be radiation leakage or radioactive material leakage by a signal from these radiation measuring devices. A radiation monitoring device, comprising: an accident type determination device that determines whether the radiation is monitored.