Experimental Study of Standardised Fluence and Dose Data, Neutron Fluence-to-Dose Conversion Factors and Quality Factors for the Health Physics Research Reactor Using the Single Sphere Albedo Technique

Abstract

The single sphere albedo technique makes use of TLD600/TLD700 detector pairs in the centre of a 30 cm polyethylene sphere and in three positions on the surface of the sphere of the Karlsruhe albedo dosemeter. Experimental results obtained with this technique have been used to establish reference data for the different neutron spectra and to analyse the neutron field at the HPRR. Data are presented for _, D, H and effective values for the fluence-to-dose/fluence-to-dose equivalent conversion factor and quality factor. The measured results are compared with ORNL reference data and with calculated data based on ORNL computed neutron spectra using the fluence-to-dose conversion factors recommended by ICRP as well as conversion factors for element 57 and for kerma in wet tissue. For the analysis of the neutron field, the neutron fluence values for thermal, epithermal and fast neutrons have been studied along with the calculated readings of the albedo and sphere detector and the attenuation factor for the reactor shields. High consistency has been found for the experimental results for five different PDIS and NAD intercomparison experiments. Measured and calculated data agree for the unshielded reactor. For the shielded reactor spectra differences between measurement and calculation are smaller than 20% for most of the data.