The effects of chelation therapy by combined administration of Ca-DTPA and Zn-DTPA on the removal of inhaled “high-fired” plutonium oxide initiated at different times after exposure were examined in rats. After inhalation of plutonium oxide, the rats were divided into four groups of five. Chelation therapy was initiated 1 day after the inhalation in the first group, 7 days after in the second group, and 14 days after in the third group, the final group was a control (no DTPA treatment). A daily dose of 150μmol/kg of Ca-DTPA was administered by peritoneal injection for the first four days and subsequently, a same dose of Zn-DTPA was given orally for 26 days. In order to examine the effects of chelation therapy, we measured lung retention of plutonium with a phoswich detector, the amount of plutonium in excreta after Ca-DTPA injection, and the plutonium contents in various organs at the end of the experiment. The results indicate that DTPA therapy is not effective in removing “high-fired” plutonium oxide from the body.
Some of the superannuated equipment were replaced in the nuclear fuel reprocessing plant at the Tokai-works of the Power Reactor and Nuclear Fuel Development Corporation (PNC). The authors have been investigating the airborne particle sizes of radiological materials in the decommissioning process using Andersen samplers. This paper describes information on the particle sizes during the cutting processes. The activity median aerodynamic diameters (AMAD) of the aerosols ranged from 2 to 4μm, and their geometric standard deviations were in the range of approximately 2-3.
From October 1988 to September 1991, we measured radon gas concentrations in different types of residential buildings in Tokyo and outlying prefectures for the purpose of evaluating potential radiation risk to the people living in the area. The characteristics of seasonal variation and relevant factors influencing the radon gas concentration levels were analyzed. However, in order to estimate the radiation risk to people, we also needed to obtain data of buildings other than residences in which people may spend time for working, shopping, etc. As a part of such investigation, we measured the indoor radon gas concentrations in four different buildings at the Tokyo Metropolitan Isotope Research Center. The average indoor concentration level in a three-storied concrete steel building was lower than that of the residential concrete steel building, and mostly showed a similar seasonal variation (i. e., higher in winter and lower in summer). The average indoor concentration level in a one-story prefabricated building was almost equivalent to that in an ordinary prefabricated residential building, but the phase of variation was different. Measurements in two other concrete steel buildings showed different average levels depending on the ventilating conditions (i. e., a lower concentration level in a more frequently ventilated room). Seasonal variations in these two buildings also showed different tendencies depending on ventilating conditions (i. e., smaller variation in a more frequently ventilated room).