HTTR benchmark analysis

Thomas Saller, University of Michigan

In collaboration with Oak Ridge National Laboratory (ORNL), we are working to develop the Nuclear Regulatory Commission’s neutronics code suite for the Next Generation Nuclear Plant (NGNP) program. The NGNP is based on an inherently safe high-temperature gas-cooled reactor which aims to meet and exceed current nuclear standards in reliability, proliferation resistance and waste management capabilities. This involves a multi-level approach in which fractions of the reactor fuel assemblies are run in high spatial detail and the results are then used in a homogenized full-core model. The fuel assembly calculations are done using ORNL’s TRITON code, a discrete ordinates solver, and the full-core calculations are done with the University of Michigan’s nodal methods code, PARCS. Part of this work included development of a triangular solver for PARCS, TRIPEN, to replace the current hexagonal solver, TPEN. This was necessary for fuel assemblies with strong heterogeneities, such as neutron-absorbing control rods inside the fuel assembly. TRIPEN is currently undergoing verification and validation. Four test cases have been run to verify the TRITON-PARCS method before moving on to the High Temperature Test Reactor (HTTR) benchmark. The HTTR is a 30 MW graphite-moderated gas-cooled prismatic research reactor operating in Japan. A fresh, critical core calculation has been done using TRITON-PARCS and compared to the benchmark, as well as a fresh, rods fully withdrawn case.

Abstract Author(s): T. Saller, V. Seker, T. Downar, B. Kochunas