Preliminary analysis of dose rates distribution of experimental power reactor 10 MW using MCNP

The reaktor daya eksperimental (RDE) is 10 MWth experimental power reactor HTR Pebble-bed type. Comparing with water pool research reactors, the distance between the core and the reactor vessel is very close while the medium mainly is graphite. Thus, the main role of the radiation shield relies on biological shields to obstruct radiation exposure coming from the reactor core. Meanwhile, the RDE reactor should be met with the operation standard safety limits of a nuclear reactor. Therefore, the purpose of this study is to estimate the radiation dose rates in the working area and outside the RDE reactor building. By analyzing the distribution of radiation dose rates can be estimated radiation safety levels for workers and society and the surrounding environment. The radiation dose rates calculation was done using MCNP. By determining the tally position, it can be determined the radiation dose rates inside and outside the RDE reactor building. The results show that the maximum dose rates on the outer surface of the biological shielding (working area) under normal operating conditions are 8 μSv/h. That dose rates are below the limit value determined by BAPETEN showing the radiation shielding design make the RDE safe for workers and the community and the surrounding environment from radiation hazards.