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The article presents a health physicist perspective regarding the Standard Model of Particle Physics. Emphasis is given to the concepts important to health physics such as neutron and muon decay characteristics, accelerator radiation types and dark matter. The significance of symmetry is also reviewed in relation to a theoretical methodology that describes processes relevant to health physics applications.

The article discusses the correlation between the radionuclide concentration and gross beta activity through the introduction and estimate of gross beta conversion factors. The gross beta concentrations in downstream water intakes of a planned inland nuclear power plant (NPP) along the Yangtze River in China are estimated. It cites the use of decay data to estimate the gross beta activity in receiving water of NPP. It provides a simple gross beta prediction method for the environmental impact of inland NPP during the siting and design period.

The article presents a study which investigated the biokinetics of radiocarbon (C) in rats during 14 weeks of continuous ingestion of C-wheat to obtain the dosimetric data on organic C ingested as food. The study showed that after the start of continuous ingestion of C-wheat, the concentration of C in both wet and dry tissues gradually increased and revealed a tendency towards a steady-state condition for most of the tissues, except adipose tissue. It also concluded that the differences in the dose rate among the tissues seemed to be mainly dependent on the variation in the organic content of each tissue.

The article describes the process used and adjustments necessary to calculate uranium mass from proportional counting measurements during the field testing phase of the Capstone Depleted Uranium (DU) Aerosol Study. The aerosol samples collected during the study were generated by the perforation of armored combat vehicles and were used to characterize the DU source term for the subsequent Human Health Risk Assessment (HHRA) of Capstone aerosols. For the samples collected during the study, it was determined that the equilibrium between the uranium isotopes and their immediate, beta-emitting progeny has been disrupted when penetrators had perforated target vehicles.

The article examines on the development of methodology in the Nuclear Test Personnel Review Program for beta dose reconstruction. Such development was due to the personnel who are present in the nuclear weapons testing that had exposed external beta doses to the skin and lens of the eye. The methodology has been applied in support of the Nuclear Test Personnel Review (NTPR) Program which was implemented by the Department of Defense. Meanwhile, the NTPR program must evaluate the radiological hazards from the nuclear testing activities as required by the Code of Federal Regulations. On the other hand, photon and neutron has been quantified for external dose assessments prior to the development of the methodology.

The computer code LUDUC (Lung Dose Uncertainty Code), developed at the University of Florida, was originally used to investigate the range of potential doses from the inhalation of either plutonium or uranium oxides. The code employs the ICRP Publication 66 Human Respiratory Tract model; however, rather than using simple point estimates for each of the model parameters associated with particle deposition, clearance, and lung-tissue dosimetry, probability density functions are ascribed to these parameters based upon detailed literature review. These distributions are subsequently sampled within LUDUC using Latin hypercube sampling techniques to generate multiple (e.g., ∼1,000) sets of input vectors (i.e., trials), each yielding a unique estimate of lung dose. In the present study, the dosimetry component of the ICRP-66 model within LUDUC has been extended to explicitly consider variations in the beta particle absorbed fraction due to corresponding uncertainties and biological variabilities in both source and target tissue depths and thicknesses within the bronchi and bronchioles of the thoracic airways. Example dose distributions are given for the inhalation of absorption Type S compounds of 90Sr (Tmax = 546 keV) and 90Y (Tmax = 2,284 keV) as a function of particle size. Over the particle size range of 0.001 to 1 μm, estimates of total lung dose vary by a factor of 10 for 90Sr particles and by a factor of 4 to 10 for 90Y particles. As the particle size increases to 10 μm, dose uncertainties reach a factor of 100 for both radionuclides. In comparisons to identical exposures scenarios run by the LUDEP 2.0 code, Reference Man doses for inhaled beta-emitters were shown to provide slightly conservative estimates of lung dose compared to those in this study where uncertainties in lung airway histology are considered. [ABSTRACT FROM AUTHOR]

Environmental air sampling uses fiberglass filters to collect particulate matter from the air and then a gas flow detector to measure the alpha and beta activity on the filter. When counted, the filter is located close to the detector so the alpha and beta particles emerging from the filter travel toward the detector at angles ranging from zero to nearly 90° to the normal to the filter surface. The particles at small angles can readily pass through the filter, but particles at large angles pass through a significant amount of filter material and can be totally absorbed. As a result, counting losses can be great. For 4 MeV alpha particles, the filter used in this experiment absorbs 43% of the alpha particles; for 7.5 MeV alphas, the absorption is 13%. The measured beta activities also can have significant counting losses. Beta particles with maximum energies of 0.2 and 2.0 MeV have absorptions of 44 and 2%, respectively. [ABSTRACT FROM AUTHOR]

Inhaling metal tritide particles is a potential occupational hazard. The radiation dose to tissue from tritide particles depends on their solubility and retention in the body. In each tritide particle, a portion of the beta particles from decay of tritium is absorbed by the metal matrix and therefore cannot contribute to absorbed radiation dose to tissue. A theoretical model for estimating the self-absorption of tritium betas in spherical metal tritide particles is presented. Numerical calculations are made with this method for titanium, zirconium, and erbium particles from 0.5 to 50 um in diameter. The tritium spectrum is divided into energy groups to facilitate estimation of the energy that escapes the particle for dose calculations. Our results show considerable absorption of beta particles and their energy, even for respirable particles smaller than 5 um. Limited experimental data of selfabsorption for titanium and zirconium tritides supported the theoretical calculation. It is concluded that the self-absorption factors should be required for counting tritide particle samples as well as for estimating absorbed radiation dose to tissue. [ABSTRACT FROM AUTHOR]

59 hot particles were collected in Kiev, Ukraine, in 1987. All but one were prepared from a moss carpet of 360 cm2 area. Radionuclide composition of the hot particles was investigated by gamma-spectrometry and beta absorption method. Pure beta emitters 90Sr and 147Pm were determined in 25 hot particles measuring the beta absorption curves of the hot particles with an end-window Geiger-Muller counter and decomposing the curves in order to obtain the contributions of 90Sr and 147Pm to the total beta counting rate. All but one of the hot particles were found to be the debris of the fuel. The activity ratio 90Sr:144Ce was 0.052 in good agreement with theoretical calculations on core inventories. This means that strontium behaved as a nonvolatile element in the process of the formation of the hot particles investigated. The activity ratio 147Pm:144Ce was 0.078 which is half of the theoretical result. Although 147Pm is considered to be a refractory nuclide, it seems that significant part of 147Pm went to the homogeneous fraction of the general fallout. The surface density of hot particles (of higher than about 50 Bq activity) was about 1,600 m-2 and that of the activities of the nuclides 90Sr, 106Ru, 134Cs, 137Cs, 144Ce and 147Pm as components of hot particles was 12.2, 54.3, 5.9, 9.7, 234 and 18.3 kBq m-2 (activity values counted for 26 April 1986), respectively, in downtown Kiev city in 1987. [ABSTRACT FROM AUTHOR]