| 摘要 |
<p>PURPOSE:To decrease the quantity of radiation toward a detecting portion by varying the positions of a radiation shielding member and a neutron detecting portion relative to a reactor core using a drive. CONSTITUTION:The neutron detecting portion 5 of a radiation source region system and the neutron detecting portion 7 of an intermediate region system are incorporated into the same detecting portion assembly 6 and each include a cable 8 and a connector 9. A radiation shielding member 10 is rotated on the detecting portion 5 and is mounted to a drive 11 in such manner that its portion 10a with a low shielding ability and its portion 10b with a high shielding ability can be switched around between the detecting portion 5 and a reactor core. The shielding member 10 is made from an element such as lead in order to efficiently attenuate gamma-rays or made from an element such as cadmium in order to shield neutrons. Most of gamma-rays and radiation such as neutrons that the detector 5 receives come from one direction from the reactor ore. The intensity of radiation impinging on the detecting portion 5 can then be varied and the quantity of radiation can be reduced up to the low intensity at which characteristic deterioration does not occur over a long period of time.</p> |
