Calculation of radiative energy release in the PIK reactor

Distribution of γ radiation in the core, vessel, light-water trap and heavy-water reflector of the PIK-type reactor is calculated by the Monte Carlo method. Inside the core due to a hard γ quanta spectrum the value of specific energy release in materials with small and medium Z is determined generally by the Compton scattering process and it is proportional to Z/A. Uranoim essential comcemtration in fuel elements leads to the increase of the absorption part (by 10-15% in comparison with a homogeneous case). The part of soft quanta in reflector and trap water is hogher than in the core due to the value of photoabsorption cross section which is lower. Materials with medium and high Z placed in water will capture soft quanta mainly in near-surface layer as the growth of photoabsorption cross section leads to strong self-shielding. For such specimens the contribution of surface absorption of soft quanta can be noticeable. It should be taken into account when gauging γ radiation detectors as well as when constructing channels and other experimental devices in the reflector and trap. Energy release from γ quanta absorbtion in the wall of a steel reactor vessel on the level of a central plane of the core can be 0.20-0.25 W/gxMW causing in it considerable temperature stresses. 8 refs.; 10 figs.; 1 tab