Masters Theses

Ying Feng

Date of Award

12-1991

Degree Type

Thesis

Degree Name

Master of Science

Major

Nuclear Engineering

Major Professor

L. F. Miller

Committee Members

J. E. Turner, D. J. Downing

Abstract

The possible occurrence of a criticality accident cannot be entirely disregarded even through the advanced technology has been developed for preventing accidents. The necessary procedures and facilities for dealing with criticality accidents must be provided to obtain a rapid dose assessment following a criticality accident for doctors to determine treatment methods for each victim.

A comprehensive study of the accident neutron dosimetry using blood and hair was performed and the results of this study are presented in this thesis. The primary objectives of this research are to establish blood-24Na and hair-32P activity measurement procedures for the accident dosimetry system at the Oak Ridge National Laboratory and to develop an accident neutron dosimetry system using blood and hair. These were accomplished through experiments conducted at the University of Tennessee, Knoxville and through calculations of blood and hair activations for 98 different neutron spectra.

A measurement procedure of blood-24Na was established based on a HPGe detector system. The sensitivity of the measurement process for a 20 ml sample is one to two rads of total neutron dose for hard spectra and below 0.5 rads for soft spectra based on 30 to 60 minute counting.

A procedure for direct counting hair samples using a liquid scintillation detector was established. About six to ten rads of total neutron dose can be measured from one gram of hair sample using this procedure. Detailed procedures for chemical dissolution and ashing hair samples were documented.

The established neutron dose assessment system using blood and hair is based on a collection of 98 neutron spectra. Ninety-eight blood activity-to-dose conversion factors were calculated. This dosimetry system make it possible to estimate the individual's neutron dose within a few hours after an accident if the accident spectrum can be approximated from one of the tabulated 98 neutron spectra.

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