The development, characterization, and performance evaluation of a new combination type personnel neutron dosimeter

A new combination type personnel neutron dosimeter has been designed and developed at the Oak Ridge National Laboratory. The combination personnel neutron dosimeter (CPND) consists of a Harshaw albedo neutron thermoluminescent dosimeter and two bubble detectors. The CPND was developed with the aim of having crude neutron spectrometric capability, universal applicability, better angular response, and an improved lower limit of detection (LLD). The CPND has been well characterized in the following areas: reusability, linearity, LLD, detection capability in mixed neutron-gamma fields, angular dependence, and neutron energy dependence. The characterization was accomplished with irradiations using a 238Pu-Be source, a 252Cf(D2O) source, a 252Cf source, a 252Cf(PE) source, monoenergetic neutrons from accelerator and reactor filtered beams, 137Cs, and X-rays. Optimum signal readout procedures, signal processing techniques, routine operational usage, and neutron dose equivalent evaluation algorithms for the CPND were developed. Various reference spectra were developed to evaluate the performance (mainly the spectrometric and the dose equivalent measurement capabilities) of the CPND. The performance of the CPND was evaluated by in-situ tests in radiation fields existing in the working environment at ORNL. The spectra in these areas were measured previously with a calibrated Bonner multisphere spectrometer. The CPND also was tested with laboratory radioisotopic sources in single-source and multi-source exposure situations. Finally, the CPND was tested by participating in the fourteenth Personnel Dosimetry Intercomparison Study. The results of the tests mentioned above demonstrated that the CPND meets the ambitious design purposes