Preconceptual Design of Multifunctional Gas-Cooled Cartridge Loop for the Versatile Test Reactor: Instrumentation and Measurement—Part II

An integrated effort by the Versatile Test Reactor (VTR) Gas-Cooled Fast Reactor (GFR) Team to develop an experiment vehicle or extended-length test assembly for the VTR experiments is led by Idaho National Laboratory and supported by an industrial partner, General Atomics, and university partners, including Texas A&M University, University of Michigan, Oregon State University, University of Houston, and University of Idaho. The focus of the effort is to design a helium gas-cooled cartridge loop (GCL) to assist with the testing of fuels, materials, and instrumentation to further support development of advanced reactor systems. This study is divided into two parts. Part I provides the functional requirements and critical irradiation data needs for advancing gas-cooled fast reactor (GFR) technologies. The objective of Part I is to describe the overall preliminary conceptual design of the VTR helium cartridge loop, the design of a fission product venting system, thermal-hydraulic effects of flow direction, and gamma-heating generation in the cartridge.

This paper, Part II, includes the measurement techniques being developed to measure the thermophysical properties of the different materials that make up the GCL, as well as the instrumentation and control system within the cartridge required for advancing GFR technologies. The purpose of Part II is to describe the functionality and efficacy of the measuring systems being developed to support the GCL. These systems include (a) a unique measurement platform that joins ion irradiation and a laser beam with an infrared camera and X-ray detection equipment developed and used to investigate more accurately and efficiently the influence of radiation and fission gases on the material properties under high temperatures; (b) a laser-induced breakdown spectroscopy to demonstrate its capability of monitoring possible fuel failure by detecting sub–part-per-million levels of xenon in the helium coolant stream, providing experimental data to better understand the interactions of fuel elements and coolant at high temperature, pressure, and fast neutron flux; (c) fiber-optic sensors with the ability to measure both the temperature demonstrated using a three-dimensional printed heat exchanger and, potentially, the strain in harsh environments; and (d) surface emissivity measurement test rigs to understand the effect of temperature, radiation, and surface finish on the silicon carbide cladding surface emissivity. Additional analyses and development, as well as integrated out-of-pile testing, are planned to demonstrate and validate the accuracy of the measuring systems and instrumentation in a more prototypic environment prior to their implementation into the VTR.