Some Aspects of Modelling MAPLE-10 Fuel

Abstract

MAPLE-10 is a small multi-purpose research reactor currently being developed in Canada for a broad range of nuclear research applications. The planned reactor total thermal power is initially up to 10 MW. The reactor is of an open pool type with light water cooled core, heavy water moderator, and heavy water and beryllium reflector. The cooling of the reactor core is achieved through forced upward flow. The core is arranged in a honeycomb geometry, with the fuel in vertically oriented bundles. A typical core contains ten 36-rod (driver) fuel bundles and six 18-rod (shim) fuel bundles. As part of the design work for the MAPLE-10 reactor, a design of UO, fuel rod (and bundle) has been established. This fuel, unlike CANDU power reactor fuel, has a free-standing sheath, suggesting the use of light water reactor (LWR) fuel design codes. We compared results from these codes and chose the most applicable options to evaluate aspects of fuel performance under normal operating conditions. Fuel centreline temperature, fission gas pressure, fuel-clad/gap conductance, sheath strain percentage, and stored energy were calculated by using both LWR and CANDU fuel computer codes. There was reasonable agreement between the "adjusted" Canadian codes and the LWR codes for this fuel. The centreline temperatures, gas release, internal gas pressures, stored energy and sheath strains are considered acceptable for the MAPLE-10 fuel lifetime, and are within the range of our experience for similar fuels.