SPECTRAL SHIFT CONTROL REACTOR BASIC PHYSICS PROGRAM. MEASUREMENT AND ANALYSIS OF PERTURBED LATTICES OF SLIGHTLY ENRICHED UO$sub 2$ MODERATED BY D$sub 2$O-H$sub 2$O MIXTURES

Spectral Shift Control Reactor Basic Physics Program: Measurement of k_∞ and Other Lattice Parameters by the Small Lattice Experiment Technique

“…However, if ideal conditions are achieved, Equation 2-2 for the poisoned test region becomes 1 = (njf e p) p (l + 6 2°°5 ) p (2)(3) where the subscript p refers to the poisoned medium. Then the infinite medium multiplication factor of the unpoisoned medium is simply P-V 1 + 5 £) (2)(3)(4) In these experiments the change in n tn due to the shift in the thermal spectrum when the medium is poisoned is negligibly small, because n for U-235 is essentially constant over the thermal range. Therefore, Equation 2-4 can be written k _ = /CLU-1-V-P-V 1 + 5 "*> (2-5) p/V p py(i + 6S) P Another modification to Equation 2-4 can be made.…”

Spectral Shift Control Reactor Basic Physics Program: Measurement and Analysis of Uniform Lattices of Slightly Enriched UO₂ Moderated by D₂O-H₂O Mixtures

“…(1/k') (ak/8821 -- Cadmium Ratio of U238 7-8 7-3. Comparison of Dy and Cu as Intermediate Foils...,.. 7 the moderator is rich in heavy water, so the neutron spectrum is epithermal, and a relatively large fraction of the excess neutrons are absorbed in the fertile material. As fuel is consumed, the moderator z. is diluted with light water, thereby shifting the spectrum toward thermal energy and providing the necessary increase in core reactivity.…”