The Niigata Prefectural Government has been carrying out an environmen
tal radiation monitoring around the Kashiwazaki Kariwa Nuclear Power S
tation. Most of the gamma-ray dose late was dependent on the natural r
adiation from the ground. ?he investigations wanted to determine the n
atural radiation level in the Kashiwazaki Kariwa area. Gamma-ray dose
rates were measured with a scintillation detector. Additionally, the q
uantity of radionuclides and their contribution to the dose rate were
obtained by an in situ measurement method.