Loss-of-Coolant Reactivity Effect

The N-Reactor lattice is fail-safe upon loss of coolant. That is the dry lattice is less reactive than the wet lattice. The primary loop coolant loss reactivity effects for the green and ripe reactor are given in Table 6.6.1.1 The value for the cold, green reactor is an esqperimental value the others are theoretical values normalized to the es rimental value. 

Loss of Coolant Reactivity Bffeot (Ak/k) Zero Bxposuare 

The NPR has an undermoderated lattice and as Just discussed loss of coolant results in a reactivity loss. Conversely addition of more moderator to the lattice may result in an. increase in reactivity. The effect of core-flo.. ding has been analyzed theoretically 5, jn the analysis the lattice was progressively flooded with water in a favored (low thermal flux) position and the maximum reactivity increase determined. Such an investigation should establish an upper bound for the effect. The calculated maxlanim /ik/k for flooding under various lattice conditions are given in Table 6.6.2.1. 

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