Potential Radiological Consequences of a Multiple Steam Generator Tube Rupture

The range of radiological consequences that could result from a multiple steam generator tube rupture event has been examined. Efforts to obtain thermal-hydraulic data for the multiple tube rupture event were only partially successful Lacking a detailed knowledge of the thermal-hydraulic characteristics of a multiple tube rupture event, a three-variable parametric study was performed. Both thyroid and whole-body exposures were determined as a function of integrated primary to secondary flow and integrated secondary relief valve flow. For all cases considered, calculated exposures were below guidelines specified in 10CFR100 and far below a level where injury might be expected. On this basis and considering the conservatism employed in the exposure estimates, it was concluded that a multiple tube rupture event would not endanger the health and safety of the public. Furthermore, it would be overly conservative, in view of the significantly lower likelihood of a multiple tube rupture event, to base primary coolant technical specifications for iodine on a multiple tube rupture event and a limit of a 1.5-rem thyroid exposure at the site boundary.