Tritium Research Laboratory Research Articles

TEST OF CAP88-PC???S PREDICTED CONCENTRATIONS OF TRITIUM IN AIR AT LAWRENCE LIVERMORE NATIONAL LABORATORY

Based on annual tritium release rates from the five sources of tritium at Lawrence Livermore National Laboratory and the Tritium Research Laboratory at Sandia National Laboratory, the regulatory dispersion and dose model, CAP88-PC, was used to predict tritium concentrations in air at perimeter and offsite air surveillance monitoring locations for 1986 through 2001. These predictions were compared with mean annual measured concentrations, based on biweekly sampling. Deterministic predictions were compared with deterministic observations using predicted-to-observed ratios. In addition, the uncertainty on observations and predictions was assessed: when the uncertainty bounds of the observations overlapped with the uncertainty bounds of the predictions, the predictions were assumed to agree with the observations with high probability. Deterministically, 54% of all predictions were higher than the observations, and 96% fell within a factor of three. Accounting for uncertainty, 75% of all predictions agreed with the observations; 87% of the predictions either matched or exceeded the observations. Predictions equaled or exceeded observations at those sampling locations towards which the wind blows most frequently, except those in the hills. Under-predictions were seen at locations towards which the wind blows infrequently when released tritium was from elevated sources. When a high fraction of tritium was from area (diffuse) sources, predictions matched observations.

Tritium Activities in the United States

There have been many significant changes in the status of tritium activities in the US since the 4th Tritium Conference in October, 1991. The replacement Tritium Facility (RTF) at Savannah River Site and the Weapons Engineering Tritium Facility (WETF) at the Los Alamos National Laboratory are now operational with tritium. The Tokamak Fusion Test Reactor (TFTR) has initiated a highly successful experimental campaign studying DT plasmas, and has produced more than 10 Megawatts (MW) of fusion power in a D-T plasma. Sandia National Laboratory has ceased tritium operations at the Tritium Research Laboratory (TRL) and many of the activities previously performed there have been transferred to Los Alamos and Savannah River. The tritium laboratory at Lawrence Livermore National Laboratory has reduced the tritium inventory to <5 grams. The Tritium Systems Test Assembly (TSTA) at Los Alamos continues to be at the forefront of tritium technology and safety development for the fusion energy program.

Tritium practices past and present

History of the production and use of tritium, as well as handling techniques, are reviewed. Handling techniques first used at Lawrence Livermore National Laboratory made use of glass vacuum systems and relatively crude ion chambers for monitoring airborne activity. The first use of inert atmosphere glove boxes demonstrated that uptake through the skin could be a serious personnel exposure problem. Growing environmental concerns in the early 1970's resulted in the implementation by the Atomic Energy Commission of a new criteria to limit atmospheric tritium releases to levels as low as practicable. An important result of the new criteria was the development of containment and recovery systems to capture tritium rather than vent it to the atmosphere. The Sandia National Laboratories, Livermore, Tritium Research Laboratory containment and decontamination systems are presented as a typical example of this technology. The application of computers to control systems is expected to provide the greatest potential for change in future tritium handling practices.