Radionuclide measurements in contaminated building water in the aftermath of the 1979 Three Mile Island (TMI) and 2011 Fukushima Daiichi (FD) nuclear power plant accidents are used to inform the development of physics-based release inventories for use in development of source terms for hypothetical severe accident scenarios. The measured radionuclide concentrations provide a basis for partitioning individual radionuclides from a given nuclear reactor core inventory to the water phase. The dissolved radionuclide partitioning can be combined with techniques that estimate core inventories as a function of reactor type, fuel mass, and burnup, to yield a general methodology for estimating the aqueous activity of individual radionuclides that could potentially be released in an accident scenario. This approach affords greater flexibility in addressing conditions different from TMI and FD. The methodology is based on the radionuclide partitioning observed at TMI and previously published estimates of radionuclide inventories for reactor cores as a function of reactor type, amount of fuel, and burnup (Ramsdell et al. 2000). In a test of the methodology using attributes of the March 2011 FD reactor core, the predicted building water radionuclide concentrations were all within a factor of two of observed. For the principal radionuclides contributing to dose, the highest aqueous activities are associated with the largest fuel mass and highest burnup.
Revised: March 27, 2014 |
Published: January 1, 2014