JPH04245000A - Disposal system of radioactive waste refuse - Google Patents

Abstract

PURPOSE:To measure and discriminate efficiently the part of radioactive concrete of a large amount of concrete waste produced on the occasion of dismantling of a building with a measure of disuse of nuclear power generation facilities, before the building is dismantled, and to conduct a rational disposal on the basis of the results thereof. CONSTITUTION:After a radioactive apparatus is removed, the amount of surface radioactivity and the depth of permeation of contamination are measured and evaluated in respect to reference values of radioactive waste refuse disposal which are expected to be set in relation to radioactive concentration. Based on these measurement and evaluation, a method of decontamination corresponding to the form of contamination is applied and thereby a contaminated part is removed. Radioactive concrete, a decontamination waste liquid, etc. thus removed are discriminated in accordance with the level of radioactivity and packed in containers. The surface of an object of measurement wherefrom the contaminated part is removed is measured again for checking, so as to confirm that the concrete thereof is not radioactive.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] The present invention relates to a radioactive waste disposal system, and in particular, to efficiently dispose of radioactive concrete waste, which is generated in large quantities during the demolition of buildings associated with the decommissioning of nuclear power generation facilities, and whose radioactivity level is unreasonably low. The present invention relates to a radioactive waste disposal system that can be disposed of automatically.

0003

2. Description of the Related Art Nuclear power generation facilities are said to have a lifespan of 30 to 40 years, and nuclear power generation facilities that have reached the end of their lifespan are dismantled and removed after being hermetically managed for a predetermined period of time. In the decommissioning process for nuclear power generation facilities, first the equipment and piping installed within the facility are dismantled and removed, and then the building is dismantled. A large amount of concrete waste is generated during building demolition, and most of it is non-radioactive, and even if it is radioactive, its radioactivity level is very low, and only the area near the surface of the building is radioactive. have. If the facility were to be dismantled without any sorting of these concrete wastes, a large amount of radioactive concrete waste would be generated, requiring large-scale storage or disposal facilities. Furthermore, when attempting to carry out differential measurements to classify all concrete waste into respective disposal destinations after facility demolition, a considerable amount of measurement and processing time is required even if a considerable number of measurement systems are used.

[0004] Therefore, it is necessary to use an efficient disposal system for the large amount of non-radioactive and low-level radioactive concrete waste that is generated during the decommissioning of nuclear power generation facilities, so that the radioactive waste can be appropriately sorted by disposal site. , and the amount of radioactive concrete waste generated can be significantly reduced. As a result, storage or disposal facilities for radioactive waste can be made smaller, and non-radioactive concrete waste, which can be treated as general waste, can be effectively used, such as in landfills. Furthermore, since the amount of radioactive waste generated can be significantly reduced and the waste can be separated, radiation exposure to workers and the general public can be reduced.

[0005]

[Problem to be solved by the invention] Until now, operations related to disposal of radioactive concrete waste, such as measurement, decontamination, and packaging, have been carried out individually. Efficiency was not achieved through equipment.

Radioactive concrete waste is divided into radioactive concrete and contaminated concrete. In the case of radioactive concrete waste, the target is the concrete located around the reactor core, and it is possible to predict the range of radioactivity and the radioactivity level of the radioactive concrete through analysis and evaluation to some extent. Furthermore, since the entire radioactive concrete is radioactive, it cannot be decontaminated, so all of that part will be removed.

On the other hand, contaminated concrete is generated when radioactive materials adhere to the building concrete surface for some reason during operation or maintenance of a nuclear power facility, and some of the radioactive materials adhering to the concrete surface are transferred internally from the building concrete surface. It may also penetrate. In the case of contaminated concrete, the contaminated location (floor, wall, ceiling), the type of contamination of the contaminated concrete (contamination only on the surface/contamination that has penetrated into the interior), and the radioactivity concentration of the contaminated material vary depending on the history of each power generation facility. Therefore, it is impossible to easily evaluate the range and radioactivity concentration using analytical methods as in the case of radioactive concrete. If the building were to be demolished without clarifying the extent of the contaminated concrete, the contaminated concrete would be mixed with non-radioactive concrete, potentially turning the entire building concrete into radioactive waste. Therefore, before dismantling the building, we will clarify the extent of contaminated concrete and its radioactivity concentration on the floors, walls, and ceilings of each room in the building, and then completely remove the contaminated concrete and dispose of it according to its radioactivity level. After doing this, it is necessary to demolish the building.

Concerning concrete waste generated during decommissioning of nuclear power generation facilities, although measurement and discrimination systems for radioactive concrete generated during equipment dismantling and removal have been studied, contaminated concrete waste must be Devices that can rationally measure and discriminate are being considered for each individual task. However, there are issues that have not been studied regarding a radioactive waste disposal system that aims to improve efficiency by systematizing the entire system and optimizing the equipment.

The present invention has been made to solve the above-mentioned problems, and it is possible to efficiently remove radioactive concrete from a large amount of concrete waste generated during building demolition due to decommissioning of nuclear power generation facilities before the building is dismantled. The objective is to provide a radioactive waste disposal system that can measure and differentiate radioactive waste and perform rational treatment based on the results. [Structure of the invention]

0010

[Means for Solving the Problems] The present invention is designed to measure surfaces to be measured such as floors, walls, and ceilings of concrete building structures in controlled areas after removing equipment, piping, etc. installed in a nuclear power generation facility. The amount of surface contamination radioactivity and the degree of contamination penetration are measured to determine whether the surface to be measured is radioactive concrete or non-radioactive concrete, and based on the determination result, if the surface to be measured is radioactive concrete, radioactive contamination is determined. Determine the type of contamination, whether it is only on the surface, permeating from the surface to the inside, or penetrating into cracks, etc. existing on the surface, and based on this determination of the type of contamination, Decontamination methods are applied to remove each contaminated part, and the removed radioactive concrete, decontamination waste liquid, etc. are classified according to the radioactivity level they contain, and then packed in containers and removed from contaminated areas. The method is characterized in that a confirmation measurement is performed again on the surface to be measured from which a portion has been removed to confirm that the concrete is non-radioactive.

[0011]

[Operation] In the disposal system configured as described above, the amount of surface contamination radioactivity and the depth of contamination penetration are precisely measured on the floors, walls, and ceilings of building structures to determine whether or not they are radioactive. For areas determined to be radioactive, decontamination such as wiping is performed if only the surface of the area is contaminated, and if the contamination has penetrated into the interior, it is determined whether the contamination is in the form of cracks or not. Determine and remove according to the penetration depth. In addition, the removed radioactive concrete, decontamination waste liquid, etc. are classified according to their radioactivity levels.

0012

[Embodiment] An embodiment of the radioactive waste according to the present invention will be explained with reference to the drawings.

FIG. 1 is a flowchart showing the steps of a processing system for explaining a first embodiment. In Figure 1, pre-dismantling survey information, equipment, and
Radioactivity measurement 2 on surfaces to be measured that may be contaminated based on prior information such as smear from pipe removal 1 and survey information
I do. In this radioactivity measurement 2, precise measurement and evaluation of the amount of surface contamination radioactivity and the degree of contamination penetration is carried out on floors, walls, and ceiling surfaces using radioactivity detectors such as Ge semiconductor detectors and NaI (Tl) scintillators. . This determines whether the surface to be measured is radioactive concrete or non-radioactive concrete. If the radioactivity measurement results in less than level 3 for disposal, it is determined to be non-radioactive. Further, at the same time as the contaminated surface is determined to be radioactive, surface condition measurement 4 is performed on the contaminated surface. In surface condition measurement 4, a combination of a radioactivity detector, an ultrasonic flaw detector, etc. is used to measure whether there is surface contamination, penetrating contamination, or crack-like contamination. Next, depending on these forms of contamination, if surface contamination is determined (5), surface contamination is removed by a decontamination method (6) such as water jetting or ice blasting. Then, radioactivity measurement 2 is performed again, and if the determination level is less than 3, the process is completed. If it is above the determination level, decontamination is carried out again or a predetermined amount of the contaminated area is removed using a mechanical surface layer removal method such as a scabler 7. In addition, if it is determined that the contamination is penetrating contamination or crack-like contamination, the contaminated portion is removed using a mechanical surface layer peeling method such as a scabler 7. Subsequent treatment operations are similar to those for surface contamination. Radioactive waste 8 such as radioactive concrete that has been decontaminated or removed and decontamination waste liquid generated due to decontamination is classified according to its radioactivity level and processed 9 such as being packed into containers. Further, after the contaminated portion has been removed, the surface to be measured is subjected to the above-mentioned treatment and then subjected to a measurement to determine whether the surface has been decontaminated to a predetermined radioactivity level. On the other hand, if the contamination cannot be removed by decontamination, the contaminated part is removed in the same manner as in the case of penetrating contamination and crack-like contamination. The above processing is performed as a series of work steps.

FIG. 2 shows an example in which each device used in the processing system necessary for the processing work shown in FIG. 1 is mounted on a trolley with a moving mechanism by remote control or the like to form a single unit. . This device can perform a series of operations of the disposal system described above, and is particularly effective when disposing of floors. That is, in FIG. 2, a cart 10 is equipped with a radioactivity detector 11, an ultrasonic flaw detector 12, a surface contamination decontamination device 13, and a mechanical surface layer stripping device 14.
, waste storage container 15 and control device 1 for these devices
It is equipped with a 6th class aircraft and has been turned into a device. For example, the radioactive waste disposal system shown in Figs.
It becomes possible to dispose of the 10,000 tons of building demolition waste that is generated as shown in Table 1.

[0015]

[Table 1]

[0016] Table 1 shows the relationship between the level and weight of general waste and radioactive (contaminated) waste after applying the disposal system according to the present invention in the case where the concrete of the building structure of a nuclear reactor facility is 500,000 tons. This is what is shown. The weight of contaminated waste is determined by applying the present invention to an area of about 15,000 m2, which is assumed to be contaminated, and considering the depth of contamination penetration.
This is an example of a trial calculation of the amount of radioactive waste generated when 5 mm is removed, and it can be seen that the present invention allows a large amount of building concrete to be sorted by disposal destination. In addition, in the example shown in Table 1, the present invention can significantly reduce the amount of radioactive waste to about 1/1000, compared to the possibility that all 500,000 tons would have become radioactive waste in the measurement and discrimination after the building was dismantled. It is possible.

FIG. 3 is a block diagram showing an example of a radioactivity concentration calculation method of the system shown in FIG. This example corresponds to a case where the allowable radioactivity concentration standard value for each disposal is expressed, for example, in Bq/ton. That is, in FIG. 3, the contamination penetration degree measurement result 1 measured by the contamination penetration measurement
Contamination removal technology 1 applied based on the degree of penetration of contamination from 7 to 18
The nuclide type or total radioactivity concentration (contained radioactivity amount/removed amount) 22 is evaluated from the amount of contaminants 20 removed by 9 and the amount of radioactivity contained in the removed portion 21. In addition, in the contamination penetration measurement, if it is assumed that there is crack-like contamination, an ultrasonic flaw detector and a radioactivity detector are used in combination to detect it. By evaluating the allowable surface radioactivity amount for each disposal in the disposal system of this embodiment, more rational discrimination of radioactive waste becomes possible.

[0018]

[Effects of the Invention] According to the present invention, it is possible to efficiently measure and evaluate residual radioactivity in controlled areas of nuclear power plant facilities, etc., and to quickly reduce the enormous amount of concrete waste from building structures. It can be disposed of in a timely and efficient manner according to its radioactivity level. As a result, the amount of radioactive waste can be significantly reduced, and waste can be rationally classified and discriminated. This can significantly shorten working time, contribute to a significant reduction in radiation exposure for workers and the general public, and reduce waste disposal costs.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an embodiment of a radioactive waste disposal system according to the present invention.

FIG. 2 is a perspective view schematically showing an example in which the disposal system in FIG. 1 is configured as a unit.

FIG. 3 is a block diagram showing an example of calculation of radioactivity concentration of the system in FIG. 1.

[Explanation of symbols]

1...Radioactive equipment/piping removal, 2...Radioactivity measurement, 3...Each disposal judgment level, 4...Surface condition measurement, 5...Contamination state judgment, 6...Water jet, ice blast, etc., 7...Scabler, etc., 8... Radioactive waste, 9... Container packing, etc., 10... Trolley,
11... Radioactivity detector, 12... Ultrasonic flaw detector, 13...
Surface contamination decontamination device, 14... Mechanical surface layer peeling device, 15...
Waste storage container, 16... Control device, 17... Contamination penetration measurement result, 18... Contamination penetration depth, 19... Contamination removal applied technology, 20... Amount removed by peeling, 21... Amount of radioactivity contained in the peeled part, 22
...Nuclide type or total radioactivity concentration.

Claims (1)

[Claims] [Claim 1] Equipment installed in a nuclear power generation facility.
Measure the amount of surface contamination radioactivity and the degree of contamination penetration on the surfaces to be measured such as floors, walls, and ceilings of concrete building structures in the controlled area after removing piping, etc., and determine whether the surfaces to be measured are radioactive concrete or non-radioactive concrete. It is determined whether the concrete is radioactive or not, and based on the determination result, if the surface to be measured is radioactive concrete, it is determined whether the radioactive contamination is only on the surface, has penetrated from the surface to the inside, or whether there are cracks, etc. on the surface. Determine the form of contamination that has entered the
Based on this judgment of the contamination form, each contaminated part is removed by applying a decontamination method according to each contamination form, and the removed radioactive concrete, decontamination waste liquid, etc. A radioactive waste disposal system is characterized in that after being classified according to the radioactivity level, the waste is packed in containers, and the surface to be measured from which contaminated parts have been removed is subjected to confirmation measurement again to confirm that it is non-radioactive concrete.