Introduction

12.104. The designations source term or fission product source terms refer to the amount and type of radioactive materials which would be available for escape to the environment from a reactor plant that has undergone a severe accident. Source term studies consider various accident sequences as described above and the chemical and physical processes that affect the transport of radionuclides from the point of origin, such as a damaged fuel element, to the environment. Probability considerations and the behavior of the radionuclides once they reach the environment are normally considered beyond the scope of source term studies.

12.105. Consideration of the fission product nuclides and their behavior during an accident release is a logical starting point in our study of accident consequences. However, space limitations prevent a detailed step-by-step discussion of the various processes that contribute to fission product trans­port during typical severe accident scenarios.