Development of a Neutron/gamma Ray Radiation Monitor.

Personnel radiation monitoring is essential to the operation of any nuclear facility and work in this area continues to strive for an accurate determination of personnel dose. In particular recent attention has been focused upon the need to improve the accuracy of neutron dosimetry, mainly because of their high Relative Biological Effectiveness. In this work the feasibility of using the NE-213 liquid scintillation detector as an efficient neutron/gamma ray radiation monitor is demonstrated. Derivative method spectrum unfolding used in MATXUF for on-line analysis of fast neutron spectra has also been applied to real time gamma spectrum unfolding (MATXUF2), making possible simultaneous on-line monitoring of both fast neutrons and gammas. To eliminate the negative fluxes in the unfolded gamma spectra created by the photopeak-compton edge combination in the plateau portion of the knee response, correcting equations using a linearized approximation to the electron recoil spectrum has been developed and incorporated in the MATXUF2 unfolding code. A neutron/gamma ray discriminator based on the method of Adams and White but using two Analog-To-Digital Converters (ADC's) similar to the design of Morris et al has also been designed and its performance evaluated by using it in combination with MATXUF and MATXUF2 to unfold neutron and gamma ray spectra for some standard sources and filters. Finally suggestions are given for the incorporation of the software and hardware into a single unit micro processor -based instrument for real time neutron/gamma ray dose and/or spectral measurements.