Distribution of the effective dose of ionizing radiation in the central hall of the IGR reactor after startups

Abstract

The paper considers the developed calculation model of the IGR reactor with an upper cover and concrete biological protection. We have simulated photon transport using the MCNP5 code and the ENDF/B‑5, 6 constant libraries. IAEA and JAEA nuclear data libraries were used to describe the characteristics of fission products, as well as the processes of uranium-235 decay and gamma-ray field formation. The proposed approach can be used to spatially visualize the operating conditions of a nuclear reactor after startups. We have assessed the field and rate of the effective dose in the central hall of the IGR reactor during its operation at a constant power of 100 MW for 40 s. The effective dose rate was determined to estimate potential radiation load on small-sized neutron detectors (fission chambers). These detectors are supposed to measure local values of fast neutron flux density during irradiation of devices in the reactor. We have validated the proposed method for calculating the effective dose of gamma radiation using the results of direct measurements in the central reactor hall. Validation results confirm the correctness of the proposed calculation models and methods, as well as the admissibility of their use for assessing the radiation situation in the central hall of the IGR reactor.