Tritium Air Concentration Calculation Using Passive Monitors.

Passive tritium air monitoring was conducted at Sandia National Laboratories' Z-Machine located in New Mexico. When conducting low-level measurements, indication of the measurement's uncertainty and of the detection limit of the counting technique are important to understand. Therefore, a calculational methodology is presented to enable the determination of the airborne tritium concentration by analysis of the minimum detectible activities for the Passive Tritium Monitoring System and the laboratory counting system used. General discussions of the advantages and disadvantages of the Passive Tritium Monitoring System are provided.

Methodology for a bounding estimate of activation source-term.

Sandia National Laboratories' Z-Machine is the world's most powerful electrical device, and experiments have been conducted that make it the world's most powerful radiation source. Because Z-Machine is used for research, an assortment of materials can be placed into the machine; these materials can be subjected to a range of nuclear reactions, producing an assortment of activation products. A methodology was developed to provide a systematic approach to evaluate different materials to be introduced into the machine as wire arrays. This methodology is based on experiment specific characteristics, physical characteristics of specific radionuclides, and experience with Z-Machine. This provides a starting point for bounding calculations of radionuclide source-term that can be used for work planning, development of work controls, and evaluating materials for introduction into the machine.

A prediction of accelerator-produced activation products.

The operational radiation protection issues associated with the Z-Machine accelerator located at Sandia National Laboratories are large: a variety of materials can be placed into the machine; these materials can be subjected to a variety of nuclear reactions, producing a variety of activation products. Without full understanding of the most likely contaminants, a realistic identification of the radiological hazards and appropriate controls is not possible. This paper presents a process developed to provide a realistic prediction of the accelerator-produced radionuclides of interest.

Development of a routine 125I bioassay program for athyrotic individuals using a pseudo uptake retention function.

Individuals working in iodine production require bioassay to determine if intakes have occurred. This is both to determine dose received for regulatory purposes and to verify whether workplace controls limiting the spread of contamination are adequate. Thyroid monitoring is commonly used as a bioassay technique to detect isotopes of iodine. If an individual performing iodine processing does not have a thyroid gland, other means must be used to determine intake and infer dose. Data was obtained from a previously published thesis that attempted to verify a model for absorption and retention of iodine by athyrotic individuals. These data were reevaluated to determine a pseudo uptake retention function. This analysis does not attempt to identify a biokinetic model, only to describe excretion of iodine and calculate an intake. Once the pseudo uptake retention function was derived, it was combined with the standard respiratory and gastrointestinal tract models as an inhalation intake retention function. A periodic urine bioassay protocol has been designed using the intake retention function described above and a conservative dose coefficient derived using organ dose coefficients for reference man, excluding the thyroid, and the appropriate weighting factors.