Impact of tritium discharged from a research reactor on concentrations in environmental water samples

A b s t r a c t . T h e d is tr ibut ion of environmental tritium concentrat ions in several samples taken near the K y o t o U n i v e r s i t y Research Reactor (KURR) was studied. The KURR Institute (KURRI) supports three major sources o f trit ium: a D 2 0 (heavy water) fac i l i ty and a Cold Neutron Source ( C N S ) fac i l i ty in the K U R R conta inment , and a tritium target fabricated in an accelerator in the crit ical a s s e m b l y bui ld ing . This report focuses on est imating the rate of release of tritium from these sources in to the env ironment , and grasping the relation between the rate and the concentrat ions in samples of water such as precipitat ion, air moisture and surface water taken near the re lease point . T h e concentrat ions of tritiated water (HTO) in the stack exhaust condensate were in the range 0 . 8 3 kBq dm" though those in air in the bui ldings that support the HTO sources ranged from 5 Bq dm" 3 to 2 kBq dm" . The HTO concentrat ions in the air decreased by ca. 1/500 within 3 0 0 m of the K U R R stack, which is f ive t imes the current global level about 5 km off-s i te . A s s e s s i n g the degree of attenuation of HTO concentrat ions in the field is informative for es t imat ing the chron ic impact of contaminants in the environment .