Nobuhito Ishigure

Analytical Solution of the Compartment Model for Respiratory Tract Clearance Used in the New ICRP Lung Model

A new ICRP human respiratory tract model, Publication 66, consists of a larger number of clearance compartments than the former lung model in Publication 30. The number of the differential equations which express the retention of inhaled materials in the compartments increases from 10 to 27 in the new model. It needs long calculation time to solve numerically the differential equations with a conventional personal computer, because the integral time sometimes reaches 50 years. In the present paper, analytical solutions of the differential equations under instantaneous intake of unit activity are presented so as to calculate rapidly the retention of the deposited activity.

Calculation of Retention and Excretion of Some Selected Radionuclides after Acute Intake by Inhalation According to New ICRP Dose Estimation Models

For interpretation of the measured data in individual monitoring for internal exposure, information to relate the measurement results with the intake of radionuclides is essential. In 1998, the International Commission on Radiological Protection (ICRP) issued Publication 78 “Individual monitoring for internal exposure of workers. This publication presented the monitoring data of retention and excretion calculated for 29 selected radionuclides (15 elements). However, there are some more radionuclides which are important from the viewpoint of occupational exposure in nuclear industry, research and medicine. In this paper, eight important radionuclides: 32P, 51Cr, 34Mn, 65Zn, 95Zr, 140Ba, 141Ce and “141Ce, were selected and the whole-body content and the daily urinary excretion for them after acute intake by inhalation were calculated, where the new ICRP human respiratory tract model and the new ICRP biokinetic models were applied.

An investigation to assess which component in the air is concerned with the vacuum effect on plastic track detector sensitivity

Abstract It has recently been found that the storage of plastic track detectors in vacuum prior to irradiation decreases the track registration sensitivity. We tested the main gases composing the air: nitrogen, oxygen and water vapour, to assess whether they could recover the sensitivity of the detector once decreased after it had been stored in a vacuum, adopting as intermediate criterion of detector sensitivity the diameters of etch pits left by normally-incident α-particles. The present results demonstrate that oxygen itself is concerned with the vacuum effect on plastic track detectors.