10.116. In designing a specific operation, attention is given to the above considerations. For example, a high-neutron-leakage geometry can be pro­vided. Neutron absorbers, such as cadmium or boron, either in solution or in a geometric array, are useful. Accumulations of fissile material that might cause problems can be avoided by careful administrative control.

10.117. Design and analysis go hand-in-hand. A prediction of criticality is necessary to confirm the adequacy of design options. This is normally done by machine calculations using suitable codes supplemented by data from critical experiments. Since a nuclear criticality safety calculation should predict a noncritical condition with high reliability, conservative values of constants and inputs should be selected when uncertainty exists. However, since safety margins are provided in the design, the calculation methods can be relatively unsophisticated, provided that the confidence level of the results is known.

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INTRODUCTION