Patent Number: 
Section: description

Preferred embodiments of the invention will be described in conjunction with the attached drawings. FIGS. 3 and 4 represent a first embodiment of a target for a neutron scattering installation according to the invention which comprises a thin-wall container body 16 arranged such that a proton beam P advancing approximately horizontally can enter a forward end of the body 16, a thin-wall container outer shell 18 for covering the container body 16 such that a space 17 is defined between the outer shell 18 and an outer surface of the body 16 and incoming- and return-passage guide vanes 19a-19d and 20a-20d installed in the container body 16. A space in the container body 16 closer to one side of the body 16 provides a liquid-heavy-metal incoming passage 21 and a space in the container body 16 closer to the other side of the body 16 provides a liquid-heavy-metal return passage 22. The container body 16 has, at its base ends, a liquid-heavy-metal inflow port 23 for inflow of the mercury M from outside to the incoming passage 21 and a liquid-heavy-metal outflow port 24 for outflow of the mercury M from the return passage 22 to outside, independently from each other. A flange 25 is mounted to surround these ports 23 and 24. The outer shell 18 is liquid-tightly mounted at its base ends to the flange 25. A portion of the outer shell 18 closer to one base end thereof is provided with a cooling-medium inflow port 26 for inflow of cooling water W to the space 17 from outside. A portion of the outer shell 18 closer to the other base end thereof is provided with a cooling-medium outflow port 27 for outflow of the cooling water W to outside from the space 17. In the space 17, a guide member (not shown) contiguous with the inner surface of the outer shell 18 and with the outer surface of the container body 16 is installed at an appropriate position, which will contribute to prevention of short-circuit flow of the cooling water W from the inflow port 26 to the outflow port 27. The incoming-passage guide vanes 19a-19d are arranged in the incoming passage 21 and have upper and lower edges contiguous with the inner surface of the container body 16. The guide vanes 19a-19d are laterally spaced apart from each other and are gradually curved toward the center of the container body 16 in a direction from the base end to the forward end of the container body 16. The return-passage guide vanes 20a-20d are arranged in the return passage 22 and have upper and lower edges contiguous with the inner surface of the container body 16. The guide vanes 20a-20d are laterally spaced apart from each other and are gradually curved toward the center of the container body 16 in a direction from the base end to the forward end of the container body 16. These guide vanes 19a-19d and 20a-20d also serve as reinforcement members for the container body 16. The container body 16 is provided, at a center of its base end, with a beam stopper 28 for blocking protons which pass through the outer shell 18 and container body 16 and advance between the guide vanes 19a-19d and 20a-20d.  When neutrons are to be generated in the target shown in FIGS. 3 and 4, the cooling water W is continuously supplied from outside of the container body 16 to the inflow port 26, passes through the space 17 and is continuously discharged through the outflow port 27 to outside of the container body 16. The mercury M is continuously supplied from outside of the container body 16 to the inflow port 23, passes through the incoming and return passages 21 and 22 and is continuously discharged through the outflow port 24 to outside of the container body 16. Under such conditions, proton beam P is irradiated so that protons pass through the outer shell 18 and container body 16 and collide against the mercury M which is flowing through the incoming and return passages 21 and 22. As a result, neutrons are generated. In the target for the neutron scattering installation as described above, the flow of the mercury M through the incoming passage 21 toward the inner forward end of the container body 16 is rectified by a plurality of incoming-passage guide vanes 19a-19d and the flow of the mercury M through the return passage 22 toward the outflow port 24 is rectified by a plurality of return-passage guide vanes 20a-20d. As a result, occurrence of stagnation and/or re-circulation flows of the mercury M at the inner forward end of the container body 16 is suppressed. Consequently, a stead and highly uniform stream of the mercury M is formed throughout in the container body 16. Therefore, increase in temperature due to stagnation of the mercury M is avoided and erosion due to re-circulation, too fast flow or the like does not occur on the inner surface of the container body 16. Flow rate of the mercury M may be adjusted by varying the distance ratio between the guide vanes 19a-19d and/or 20a-20d.  Further, heat generated by nuclear spallation reaction can be removed by mercury and the cooling water W passing through the space 17, which will relieve thermal load on the container body 16, outer shell 18 and mercury M and alleviate the burden on cooling means of, for example, a pump 14 for circulating the mercury M and a heat exchanger 15 (FIG. 2). Thus, nuclear spallation reaction having higher heat generated can be coped with. Furthermore, since the thermal load is relieved as described above and the guide vanes 19a-19d and 20a-20d are used as reinforcement members for the container body 16, the container body 16 and outer shell 18 can be designed with thin wall, which will contribute to improvement of the efficiency to generate neutrons. In addition, the container body 16 in which the mercury M flows is covered with the outer shell 18, which will prevent any leakage of the mercury M to outside as may occur when the container body 16 is damaged. FIGS. 5 and 6 represent a second embodiment of a target for a neutron scattering installation of the present invention which comprises a thin-wall container body 31 arranged such that a proton beam P advancing approximately horizontally can enter a forward end of the body 31, a thin-wall container intermediate shell 33 for covering the container body 31 such that a space 32 is defined between the intermediate shell and an outer surface of the container body 31, a thin-wall container outer shell 35 for covering the intermediate shell 33 such that a space 34 is defined between the outer shell 35 and an outer surface of the intermediate shell 33 and incoming- and return-passage guide vanes 36a-36d and 37a-37d installed in the container body 31. A space in the container body 31 closer to one side of the body 31 provides a liquid-heavy-metal incoming passage 38 and a space in the container body 31 closer to the other side of the body 31 provides a liquid-heavy-metal return passage 39. The container body 31 has, at its base ends, a liquid-heavy-metal inflow port 40 for inflow of the mercury M from, outside to the incoming passage 38 and a liquid-heavy-metal outflow port 41 for outflow of the mercury M from the return passage 39 to outside, independently from each other. The container body 31 and intermediate shell 33 are closely fitted at,their base ends to each other to close a base end portion of the space 32 which is filled with helium (He) gas. The intermediate and outer shells 33 and 35 are closely fitted at their base ends to each other to close a base end portion of the space 34. Through a cooling-medium feed passage (not shown), heavy water is supplied from outside of the container body 31 to the space 34 and is discharged to outside of the container body 31 via a cooling-medium discharge passage (not shown). In the space 34, a guide member (not shown) contiguous with the inner surface of the outer shell 35 and outer surface of the intermediate shell 33 is installed at appropriate position, which will contribute to prevention of short-circuit flow of the heavy water from the cooling-medium feed passage to the cooling-medium discharge passage. The incoming-passage guide vanes 36a-36d are arranged in the incoming passage 38 and have upper and lower edges contiguous with the inner surface of the container body 31. The guide vanes 36a-36d are laterally spaced apart from each other and are gradually curved toward the center of the container body 31 in a direction from the base end toward the forward end of the container body 31. The return-passage guide vanes 37a-37d are arranged in the return passage 39 and have upper and lower edges contiguous with the inner surface of the container body 31. The guide vanes 37a-37d are laterally spaced apart from each other and are gradually curved toward the center of the container body 31 in a direction from the base end to the forward end of the container body 31. These guide vanes 36a-36d and 37a-37d also serve as reinforcement members for the container body 31. The container body 31 is provided, at a center of its base end, with a beam stopper 42 for blocking protons, which pass through the outer shell 35, intermediate shell 33, and container body 31 and advance between the guide vanes 36a-36d and 37a-37d.  When neutrons are to be generated in the target shown in FIGS. 5 and 6, the heavy water is continuously supplied from outside of the container body 31 to the feed passage, passes through the space 34 and is continuously discharged through the discharge passage to outside of the container body 31. The mercury M is continuously supplied from outside of the container body 31 to the inflow port 40, passes through the incoming and return passages and 3839 and is continuously discharged through the outflow port 41 to outside of the container body 31. Under such conditions, proton beam P is irradiated so that protons pass through the outer shell 35, intermediate shell 33 and container body 31 and collide against the mercury M which is flowing through the incoming and return passage 38 and 39. As a result, neutrons are generated. In the target for neutron scattering installation as described above, the flow of the mercury M through the incoming passage 38 toward the inner forward end of the container body 31 is rectified by a plurality of the incoming-passage guide vanes 36a-36d and the flow on the mercury M through the return passage 39 toward the outflow port 41 is rectified by a plurality of return-passage guide vanes 37a-37d. As a result, occurrence of stagnation and/or re-circulation flows of the mercury M at the inner forward end of the container body 31 is suppressed. Consequently, highly uniform and steadily flowing stream of the mercury M is formed throughout in the container body 31. Therefore, increase in temperature due to stagnation of the mercury M is avoided and erosion due to recirculation, too fast flow or the like does not occur on the inner surface of the container body 31. Flow rate of the mercury M may be adjusted by varying the distance ratio between the guide vanes 36a-36d and/or 37a-37d.  Further, heat generated by nuclear spallation reaction can be removed by mercury and the heavy water passing through the space 34, which will relieve thermal load on the container body 31, intermediate shell 33, outer shell 35 and mercury M and alleviate the burden on cooling means of, for example, a pump 14 for circulating the mercury M and a heat exchanger 15 (FIG. 4). Thus, nuclear spallation reaction having high heat generated can be coped with. Furthermore, since the thermal load is relieved as described above and the guide vanes 36a-36d and 37a-37d are used as reinforcement members for the container body 31, the container body 31 and intermediate shell 33 can be designed with thin wall, which will contribute to improvement of the efficiency to generate neutrons. In addition, the container body 31 in which the mercury M flows is dually covered by the intermediate and outer shells 33 and 35, which will prevent any leakage of the mercury M to outside as may occur when the container body 31 is damaged. The space 32 may be filled with fluid other than helium. Fluid other than heavy water may be passed through the space 34.