12.107. In considering the hazards of fission product release in an ac­cident sequence, a number of factors determine the importance of indi­vidual radionuclides.

1. The total core inventory of the isotope. This depends on the balance between formation from fission, destruction, and decay as discussed in §2.203 et seq.

2. Chemical properties determine reactions that may occur during the accident sequence which could affect transport of the isotope.

3. Physical properties and characteristics such as volatility, particle size, and deposition behavior require attention.

4. Radiological and biological importance. Such matters as postaccident iso­topic changes, biological uptake and half-life, and specific effects on organs are all relevant.