| 摘要 |
A nuclear reactor arrangement (1), esp. a boiling water reactor, comprises the following sections: (A) reactor tank (2); (B) pipe (4) for supplying coolant, pref. water; (C) coolant supply inlet (5) in the tank wall; (D) steam outlet (6) in the upper part of the tank; (E) pipe (8) for coolant vapour produced during operation of the reactor; (F) circulation pump (9) in the lower part of the tank for passing coolant through a reactor core (10) located in the tank, which has vertical elongated fuel rods and into which control rods can be lowered parallel with the fuel rods, so that coolant can flow upwards through the core; (G) first radiation level detector (12); (H) second radioactivity detector (14) positioned near the first detector; (I) radiation shield (20) which is more effective against photon with an energy of 1 MeV than against photons with higher energies; and (J) evaluation unit (16) that compares the signals received from the two detectors in order to detect a change in the radiation level for photons with an energy of ca. 1 MeV; Also claimed are (i) a radioactivity measuring device for a nuclear reactor comprising components (G) - (H), and (ii) a method for the detection of radiation due to relatively low energy photons from fission gases, in the presence of higher energy photons from other radioactive materials, using the device, in which the damping factors (K1, K2) by which the second detector is protected by the shield against low and high energy photons respectively are combined with the two detector signals (D1, D2), from which the more energy-rich signal is filtered out to leave a signal (DX) representing the lower photon energy radiation. |
