The alternative low-enriched uranium (LEU) design for the; FRM-II proposed by the Reduced Enrichment Research and Test Reactor (RERTR) Program at Argonne National Laboratory (ANL) has a compact core consisting of a single fuel element that uses LEU (<20%) silicide fuel with 4.5 g U/cm{sup 3} and operates at 32 MW. Both the high-enriched uranium (HEU) (93%) design by the Technical University of Munich (TUM) and the LEU design have the same fuel lifetime (50 days) and the same neutron flux performance (8 X 10{sup 14} n/cm{sup 2}{center_dot}s in the reflector). Computer models for the HEU and LEU designs have been exchanged between TUM and ANL, and discrepancies have been resolved.

An alternative LEU design for the FRM-II

The Alternative LEU Design for the FRM-II proposed by the RERTR Program at Argonne National Laboratory (ANL) has a compact core consisting of a single fuel element that uses LEU silicide fuel with a uranium density of 4.5 g/cm{sup 3} and has a power level of 32 MW. Both the HEU design by the Technical University of Munich (TUM) and the alternative LEU design by ANL have the same fuel lifetime (50 days) and the same neutron flux performance. LEU silicide fuel with 4.5 g/cm{sup 3} has been thoroughly tested and is fully-qualified, licensable, and available now for use in a high flux reactor such as the FRM-II. The following issues raised by TUM were addressed in Ref. 1: qualification of HEU and LEU silicide fuels, gamma heating in the heavy water reflector, radiological consequences of larger fission product and plutonium inventories in the LEU core, and cost and schedule. The conclusions of these analyses are summarized below. This paper addresses three additional safety issues that were raised by TUM in Ref. 2: stability of the involute fuel plates, a hypothetical accident involving the configuration of the reflector, and a loss of primary coolant flow transient due to an interrupted power supply. Based on the excellent results for the Alternative LEU Design that were obtained in these analyses, the RERTR Program concludes that all of the major technical issues regarding use of LEU fuel instead of HEU fuel in the FRM-II have been successfully resolved and that it is definitely feasible to use LEU fuel in the FRM-II without compromising the safety or performance of the facility.

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Numerical investigation of hydraulic instability of circular arc shell-type fuel elements under axial flow conditions

The thin fuel plates planned for the Advanced Neutron Source are to be cooled by forcing heavy water at high velocity, 25 m/s, through thin cooling channels on each side of each plate. Because the potential for structural failure of the plates is a design concern, considerable effort has been expended in assessing this potential. As part of this effort, experimental flow tests and analyses to evaluate the structural response of circular arc plates have been conducted, and the results are given in this report.

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R.L. Battiste

Papers

Circular arc fuel plate stability experiments and analyses for the advanced neutron source