ANALYSIS OF ²³⁵U-Pu-²³⁸U-FUELED TIGHT-LATTICE WATER REACTORS.

When **2**3**5U is introduced into **2**3**8U-Pu-fueled tight-lattice water reactors, it improves the performance of these reactors in two ways. First, **2**3**5U tends to improve the reactivity void response of the core by making it less positive or even negative. Second, introducing **2**3**5U makes a high conversion reactor breed with respect to plutonium. This impacts positively on the plutonium inventory and the rate of the introduction of the high conversion tight-lattice reactors.