Determination of absorbed and effective dose from natural background radiation around a nuclear research facility

This paper presents result of outdoor absorbed dose rate and estimated effective dose from the naturally occurring radionuclides ''2''3''2Th, and 238U series 40K, around Centre for Energy Research and Training, Zaria, Nigeria, using high-resolution in-situ gamma ray spectrometer. CERT houses a 30kW research reactor and other neutron and gamma sources for research and training. The values of absorbed dose rate in air for 232Th, 238U and 40K range from 8.2±2.5 to 24.5±3.6 nGyh-1, 1.9±1.2 to 4.6±2.5 nGyh-1 and 12.2±5 to 38±6.7 nGyh-1 respectively. The estimated total annual effective dose for the sites range from 27.3 to 79.9μSvy-1. This showed that radiation exposure level for the public is lower than the recommended value of 1mSvy-1. Hence, the extensive usage of radioactive materials within and around CERT does not appear to have any impact on the radiation burden of the environment.