THE IMPACT OF NEW ICRU95 QUANTITIES AND SPECTRUM DATA ON THE DOSIMETRIC QUANTITIES OF THE NEUTRON REFERENCE FIELDS AT PTB.

In 2020, the ICRU released a new report which includes the re-definition of the operational quantities used in radiation protection and new conversion coefficients from physical quantities to operational radiation protection quantities. An assessment of the ambient and personal dose conversion coefficients for the reference neutron fields of radionuclide sources at PTB is necessary based on these new definitions. In this work, a numerical estimation of the conversion coefficients of moderated and unmoderated 252Cf and 241Am-Be neutron sources based on ICRU57 and ICRU95 reports and using spectrum data available in the ISO 8529-1 standard and at PTB are discussed. Two numerical approaches are used for this estimation to ensure the reliability of the calculated values: a direct calculation using MCNP6, and cubic interpolation of conversion coefficients datasets written in Python. The results show large differences between the spectrum-averaged operational quantities for the current and new conversion coefficients of up to 23%. The choice of spectrum data affects conversion coefficient values by 6-8%.

CALCULATIONS FOR THE HEAVY WATER MODERATED 252CF REFERENCE FIELDS AT PTB.

Knowledge of the neutron spectra of reference fields is very important for calibration purposes. This paper presents new calculations of the neutron spectra and dosimetric parameters of a D2O moderated 252Cf source assembly used to produce a neutron reference field at the Physikalisch-Technische Bundeanstalt (PTB), based on recent 252Cf fission neutron spectrum data and conversion coefficients for operational radiation protection units recommended by the International Commission on Radiological Protection (ICRP) report 57. Neutron fluence and dose calculations were carried out using a detailed simulation model of the source assembly implemented using MCNP6 and the cross-section data library ENDF/B-VIII.0. The PTB moderator was compared with the International Organization for Standardization, ISO 8529 model and to previous calculations done at PTB. The results show differences to the previous calculations performed at PTB of the order of 5% and a slight discrepancy with the ISO 8529 moderator model regarding the values of the operational quantities.

Comparison study of CR-39 and CN-85 detectors to evaluate the alpha radioactivity of some samples of drinks in Iraq.

Radon and progeny concentration measurements in various drink samples are intrinsically important for assessing the health risks resulting from daily consumption of these drinks. In this study the comparison between two Solid State Nuclear Track Detectors (SSNTDs), the CR-39 and the CN-85 has been conducted for the purpose of evaluating the radon concentration, annual effective dose, the rate of exhalation of radon and the effective radium content in thirty-two different samples of soft drink, water, and milk available in the local Iraq markets. The results showed that there are significant differences in the measurement results for the two detectors. The annual effective dose of the investigated samples is still below the limit of International Commission on Radiological Protection (ICRP) recommendation in the measurements of both detectors.