Effect of coolant channel width on group constants and multiplication factor of research reactors using MTR type low enriched uranium fuel

One dimensional transport theory lattice code WIMS-D/4 and three dimensiona l diffusion theory code CITATION have been used to study the effect of fuel loading on critical cores of low enriched uranium (LEU) fuelled material t esting reactors (MTRs). The fuel loading in a fuel element was varied by ch anging the fuel density in the fuel meat. In order to keep the reactor crit ically moderated, the optimal coolant channel width for a given fuel loadin g was calculated. For the purpose of optimization, the group constants D, S igma (a) and v Sigma (f), and infinite multiplication factor (k(infinity)) were calculated as a function of coolant channel width using wims-D/4. An i ncrease in U-235 loading per fuel plate results in an increase in the optim al coolant channel width and k(infinity) The calculated values were found t o be in good agreement with the typical design of MTR, CITATION was then us ed to determine the critical cores for different fuel loading with optimize d fuel dimensions. Both critical mass and volume were found to decrease wit h an increase in the fuel loading. The criticality studies of Pakistan rese arch reactor-1 (PARR-1) are in good agreement with the predictions. (C) 200 1 Elsevier Science Ltd. All rights reserved.