WO2015199372A1

WO2015199372A1 - Method for preparing isotopes using heavy water nuclear reactor

Info

Publication number: WO2015199372A1
Application number: PCT/KR2015/006134
Authority: WO
Inventors: 박윤원
Original assignee: 박윤원
Priority date: 2014-06-24
Filing date: 2015-06-17
Publication date: 2015-12-30
Also published as: KR101502414B1; CA2950762A1; CA2950762C

Abstract

The present invention relates to a method for preparing isotopes using a heavy water nuclear reactor, and specifically, to a method for preparing isotopes using a heavy water nuclear reactor in which bundles comprising an isotope target including Co-59 (or Mo-99), instead of nuclear fuel pallets of natural uranium, are inserted into some nuclear fuel channels of a CANDU type nuclear reactor composed of 380 nuclear fuel channels, to radiate neutrons, thereby mass-producing Co-60 through the conversion of Co-59 into Co-60.

Description

Isotope production method using heavy water reactor

The present invention relates to a method for producing radioisotopes in deuterium reactors.

Nuclear power plant reactors are divided into light and heavy water reactors depending on whether they are cooled by ordinary light or heavy water. Most of them are light water reactors in Korea, but Wolsong Units 1, 2, 3, and 4 are heavy water reactors built on Canadian technology. Unlike the light reactor, which loads the fuel bundles vertically at once in the reactor, there are 380 fuel channels and 12 fuel bundles are charged in each fuel channel (FIGS. 1 and 2). The fuel in the heavy water reactor is made of natural uranium, and the fuel called pallet is filled in Zr Fuel Sheath made of Zircaloy alloy, sealed and bundled into 36 bundles. (FIG. 3). These fuel bundles are loaded into 12 fuel channels, and the fueling machine is the one that loads the fuel bundles into the fuel channel and takes out the used fuel bundles. In particular, because heavy water reactors use natural fuel, the fuel must be frequently replaced with new ones. Each time the fuel loader opens both ends of the fuel channel and charges and withdraws the fuel bundles. Usually, 380 fuel channels need to be completely replaced once a year because they will reload the same number of fuel bundles (approximately 23-24 fuel bundles) and take out the same number of burned fuels per day. Unlike light water reactors, however, nuclear fuel can be replaced during normal power operation. Spent fuel, which is a high-level radioactive waste, is equipped to be transported to prevent human exposure from the nuclear fuel loader to the spent fuel storage tank (FIG. 6).

Due to the characteristics of the heavy water reactor, the output coefficient is determined by the combination of three fuel temperature coefficients, coolant temperature coefficients, and moderator temperature coefficients. If you need to lower the output part of the heavy water reactor, you have to inject negative reactivity to absorb some of the neutrons coming out of the output.In the current method, you can insert an adjuster rod, a small amount of coolant. Boric acid is added, and the level of the liquid zone controller is increased. However, in all three cases, from the point of view of nuclear fuel combustion, it is true that the output is lost as much as it is lost. The present invention proposes a method for mass-producing a useful radioisotope by irradiating a radioisotope target with these neutrons, rather than the conventional method of capturing surplus neutrons by inserting (-) reactivity to reduce the output. I would like to.

The existing method of producing Co-60 in the heavy water reactor is to use 21 adjuster rods installed in the Callandria for the purpose of controlling the reactivity of the heavy water reactor (see FIG. 7). This control rod is made of stainless steel (Fig. 10), and it is necessary to work on the calandaria bolt as shown in Fig. 7 for installation and withdrawal. At this time, in order to withdraw and charge the control rod, all work must be done by man opening the gate at the upper part of the calandaria bolt, removing the control rod, and then inserting the heavy transport container into the manual crane to avoid exposure. It is necessary to put the adjusting rod drawn out of the water in the calandaria bolt by hanging it so that it is submerged in the calandaria bolt. This means that once the worker has to stay on the calandria bolt, there is a very high chance of excessive exposure, and the heavy transport container must be suspended from the calandaria bolt, and the drive cable must be connected and cut again during installation and withdrawal. There is a high possibility of foreign matter entering the calandria bolt due to work, and the upper part of the calandaria bolt is equipped with various facilities such as the control rod of the first stop system in addition to the adjusting rod, which can damage them. There is a difficulty to perform the task of repeatedly. Therefore, installation and withdrawal operations are possible only during the period of preventive maintenance of the reactors accessible to the Calandaria bolts, that is, at least one year or more, and each time a large container must be put into the containment building and removed. As a result, it is inconvenient to open and close the equipment hatch.

The present invention has been made to solve the above problems, the object of the present invention, when the operation is to lower the output of a certain portion in the heavy water reactor, it is necessary to absorb a portion of the neutron coming out of the output by injecting a negative (-) reactivity Current methods include inserting an adjuster rod, adding a small amount of boric acid to the coolant, and raising the level of the liquid zone controller. However, in all three cases, from the point of view of nuclear fuel combustion, it is true that the output is lost as much as it is lost. The present invention proposes a method for mass-producing a useful radioisotope by irradiating a radioisotope target with these neutrons, rather than the conventional method of capturing surplus neutrons by inserting (-) reactivity to reduce the output. I would like to.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. Furthermore, the objects and advantages of the present invention can be realized by means and combinations indicated in the claims.

The present invention is a means for solving the above problems, by producing a bundle of a target bundle inserted with a radio target including Co-59 in place of the nuclear fuel pellets in the heavy fuel cell fuel rods, and the same co-59 in some fuel channels By loading elemental target bundles to investigate neutrons in heavy water operation, large-scale production of Co-60 is achieved by allowing Co-59 to be converted to Co-60 and periodically removing the isotopic target bundles containing the converted Co-60. To be done. In this case, from the viewpoint of reactivity control, the target bundle containing Co-59 is to insert (-) reactivity in the core instead of the three conventional methods described above. If the output is evenly distributed over 380 channels, the quantity of nuclear fuel channel (Ne) corresponding to the output reduction can be determined proportionally, such as 38 channels if the output is reduced by 10%. This can be done by preventing output from the fuel channel or by absorbing 10% of the neutrons throughout the core. Therefore, in the present invention, some of the nuclear fuel channels Ne (e.g., Ne / 2) are charged with the normal fuel, and the remaining (e.g., Ne / 2) are charged with the surplus output part by charging the bundle containing the Co-59 target. It absorbs neutrons from Ne / 2 channels into other Ne / 2 channels, lowers the output as much as necessary and operates only in safe area, satisfies safety, and absorbs neutrons with excess output (Ne / 2). By producing Co-60, a useful radioisotope, it is possible to compensate for economic losses.

In addition, the co-target bundle proposed in the present invention is charged and withdrawn using the same procedures and methods as the handling of fuel bundles when replacing fuels, so it may cause problems such as overexposure, damage to other equipment, and the like. There is no possibility of problems such as foreign matter entering into the calandaria bolt. In addition, since fuel replacement is performed every day, the loading and withdrawal of Co targets is possible at any time as needed, so that Co can be supplied in a timely manner when Co supply is required, and loading the extracted Co target bundles into a transport container is also possible. Since it is possible to work in the tank, it can be freed from the time constraints such as waiting for the planned preventive maintenance period as in the conventional method.

As described above, radioisotopes are widely used for nondestructive testing in the industry, and are widely used for radiotherapy, sterilization and disinfection, and diagnostic tests in the pharmaceutical industry. Among these radioisotopes, Co-60 accounts for more than 45% of the total market, and the half-life is about 5.2 years, which is sufficiently long, transformed into stable beta-decomposed Ni-60. Emit gamma rays of 1.17 MeV and 1.33 MeV, respectively.

One gram of Co-60 emits 44 TBq (1100 Ci) of radiation through its half-life decay. The Co-60 can be produced in heavy water reactors, providing 83% of the world's supply in Canada, where heavy water reactors are located. In Canada, however, the closure of G-2 reactors, which accounted for a large portion of Co-60 production, is expected to cause serious disruptions to Co-60 supply worldwide. There are 4 heavy water reactors in Korea, but they do not produce Co-60, so they need to rely on imports. Therefore, the present invention is capable of mass production of Co-60 by using No. 1, 2, 3, and 4 as Wolseong Heavy Water in Korea, and has the effect of sufficiently producing domestic exports as well as domestic demand.

1 is an internal structural diagram of an embodiment showing the structure of a CANDU reactor.

2 is a structural diagram of an embodiment showing the structure and fuel channel of the CANDU reactor.

3 is a perspective view of one embodiment showing a CANDU reactor fuel and fuel bundles.

4 is a cross-sectional view of one embodiment of a cross section of a CANDU fuel bundle.

FIG. 5 is an illustration of one example showing a CANDU reactor fuel replacement and a fuel loader. FIG.

Figure 6 is a block diagram of an embodiment showing the CANDU fuel loading and withdrawal path.

Figure 7 is an internal perspective view of one embodiment showing the CANDU reactor structure and adjuster rod position.

FIG. 8 shows decay and gamma emission, CANDU core fission reaction and neutron balance (from CNSC Training Manual for CANDU Reactor Physics) of Co-60.

FIG. 9 is a diagram illustrating an embodiment showing the heavy water reactor fuel channel Index and adjuster rod position. FIG.

FIG. 10 is an internal perspective view of one embodiment showing an adjuster rod of a heavy water reactor. FIG.

Before describing the various embodiments of the present invention in detail, it will be appreciated that the application is not limited to the details of construction and arrangement of components described in the following detailed description or illustrated in the drawings. The invention can be implemented and carried out in other embodiments and can be carried out in various ways. In addition, device or element orientation (e.g., "front", "back", "up", "down", "top", "bottom" The expressions and predicates used herein with respect to terms such as "," "left", "right", "lateral", etc. are used merely to simplify the description of the present invention, and related apparatus. Or it will be appreciated that the element does not simply indicate or mean that it should have a particular direction.

The present invention has the following features to achieve the above object.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

Looking at one embodiment according to the present invention, characterized in that the isotope is prepared by inserting the target bundle consisting of a plurality of radioisotope targets in a predetermined region of the mounting hole of the nuclear reactor nuclear reactor fuel rods.

In addition, the target bundle is inserted into the nuclear reactor reactor, by irradiating the neutron during the operation of the reactor, the internal radioisotope Co-59 is converted to Co-60, the target bundle containing the changed Co-60 periodically It is characterized in that to be discharged to produce Co-60.

In addition, when the reactor has to operate at a lower output, the reactor is injected with a negative reactivity corresponding to the lowered output so that the surplus neutrons emitted during the output can be irradiated to the radioisotope target. It is characterized in that the production of can be increased.

In addition, the radioisotope target is characterized in that the pallet having a cobalt material.

Hereinafter, a method for producing isotopes using a deuterium reactor according to a preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 10.

As shown, an isotope manufacturing method using a heavy reactor reactor according to the present invention by producing a target bundle containing a radio-target including Co-59 in place of the nuclear fuel pellet in the nuclear fuel rod of the heavy reactor reactor, the Co in the fuel channel By charging isotope target bundles containing -59 and investigating the neutrons in heavy water operation, the Co-59 is converted to Co-60 and periodically removed from the converted isotopic target bundles containing Co-60. Allow Co-60 to be produced.

At this time, from the viewpoint of reactivity control, the target bundle containing Co-59 is to insert (-) reactivity in the core instead of the three conventional methods. If the output is evenly distributed over 380 channels, the quantity of nuclear fuel channel (Ne) corresponding to the output reduction can be determined proportionally, such as 38 channels if the output is reduced by 10%. This can be done by preventing output from the fuel channel or by absorbing 10% of the neutrons throughout the core. Therefore, in the present invention, some of the nuclear fuel channels Ne (e.g., Ne / 2) are charged with the normal fuel, and the remaining (e.g., Ne / 2) are charged with the surplus output part by charging the bundle containing the Co-59 target. It absorbs neutrons from Ne / 2 channels into other Ne / 2 channels, lowers the output as much as necessary and operates only in safe area, satisfies safety, and absorbs neutrons with excess output (Ne / 2). By producing Co-60, a useful radioisotope, it is possible to compensate for economic losses.

The existing way of producing Co-60 in heavy water reactors is to use 21 adjuster rods installed in Callandia to control the reactivity of the heavy water reactors (see Figure 7). This control rod is made of stainless steel, and in order to install and withdraw it, it is necessary to work on the calandaria bolt as shown in FIG. At this time, in order to withdraw and charge the control rod, all work must be done by opening the gate at the upper part of the calandaria bolt, removing the control rod, and inserting the heavy transport container into the manual crane to avoid exposure. It is necessary to put the adjusting rod drawn out of the water in the calandaria bolt by hanging it so that it is submerged in the calandaria bolt. This means that once the worker has to stay on the calandria bolt, there is a very high chance of excessive exposure, and the heavy transport container must be suspended from the calandaria bolt, and the drive cable must be connected and cut again during installation and withdrawal. There is a high possibility of foreign matter entering the calandria bolt due to work, and the upper part of the calandaria bolt is equipped with various facilities such as the control rod of the first stop system in addition to the adjusting rod, which can damage them. There is a difficulty to repeatedly perform the task of difficulty. Therefore, installation and withdrawal operations are possible only during the period of preventive maintenance of the reactors accessible to the Calandaria bolts, that is, at least one year or more, and each time a large container must be put into the containment building and removed. As a result, it is inconvenient to open and close the equipment hatch.

In heavy water reactors, the fuel is replaced using a fueling machine (Refueling Machine) for about 2 channels (about 23 ~ 24 fuel bundles) every day. When the fuel loader is used, the charge and withdrawal of fuel bundles Since there is little possibility of exposure because it is not touched directly, the extracted spent fuel with very high radiation level can be moved in the fuel magazine's internal magazine, making handling very easy. The spent fuel contained in the magazine of the nuclear fuel loader is safely discharged while submerged in the spent fuel discharge tank as shown in FIG. 6 and finally transferred to the spent fuel storage tank located outside the containment building along the transfer route in the water. . In particular, damaged fuel, which is a problem in the extracted fuel, can be sealed in a can in a spent fuel discharge tank and safely transported to a damaged fuel storage tank next to the spent fuel storage tank outside the containment building. This work is always done at the time of nuclear fuel replacement, and all processes are automated and under water, with little chance of an operator being exposed and rarely disturbing other work.

Co target bundle proposed in the present invention is charged and withdrawn using the same procedures and methods as the handling of such fuel bundles, so the problem of overexposure, damage to other facilities, and calandria bolts, as with the conventional control rods. There is no possibility of problems such as foreign matter inflow. In addition, since fuel replacement is performed every day, the loading and withdrawal of Co targets is possible at any time as needed, so that Co can be supplied in a timely manner when Co supply is required, and loading the extracted Co target bundles into a transport container is also possible. Since it is possible to work in the tank, it can be freed from the time constraints such as waiting for the planned preventive maintenance period as in the conventional method.

Theoretical Co-60 productivity (when irradiated with 1g Co-59 in the neutron flux)

(from PRODUCTION OF COBALT-60 IN PARR-1 / KANUPP (CANDU), Mushtaq Ahmad

Isotope Production Division, PINSTECH, Islamabad)

As mentioned above, although this invention was demonstrated by the limited Example and drawing, this invention is not limited by this and is described below by the person of ordinary skill in the art, and the following. Various modifications and changes may be made without departing from the scope of the appended claims.

Claims

In order to enable mass production of radioisotopes, while replacing them with the same procedures and methods as for heavy water reactor fuel bundles,

Some of the fuel channels equipped with heavy fuel reactors are equipped with nuclear fuel bundles replaced with radio targets to produce fuel pellets in the fuel rods constituting the fuel bundles. Manufacturing,

The nuclear fuel bundles containing the radiation targets are inserted into the reactors and irradiated with neutrons, thereby converting the internal radioisotope Co-59 to Co-60, and the fuel bundles containing the converted Co-60. Isotope production method using a heavy water reactor, characterized in that to be periodically discharged to the outside to produce Co-60.