High Temperature Test Laboratory
Established in the 1990s, the High Temperature Test Laboratory (HTTL) attracts work from key U.S. and international research organizations to study severe accidents in nuclear reactors. It is a multi-purpose facility that is uniquely equipped for such research.
In recent years, the HTTL staff has attracted funding for high temperature material property testing and for instrumentation development and testing from a host of nuclear and non-nuclear programs. Development activities have already led to several specialized sensors, such as the High Temperature Irradiation Resistant Thermocouples (HTIR-TCs), the Transient Hot Wire Method Needle Probe (THWM NP), silicon carbide temperature monitors, a creep test rig, and encapsulated melt wires and flux wires, for in-pile high temperature measurements of fuels during irradiation. Specialized equipment for instrumentation fabrication and evaluation at the HTTL to support this project includes several high temperature tube furnaces, a high temperature vacuum furnace, several autoclaves, a laser welder, and a real-time x-ray imaging system.
The HTTL has established itself in the international community with an impressive number of publications in archival journals and peer-reviewed conference proceedings. Several products developed by this group have received patents or have patents pending. Efforts are underway to relocate the HTTL to the new REL building that is under construction in Idaho Falls. In addition to existing HTTL equipment, this new facility will include several new features such as a clean-room capability for sensor fabrication.
Below are HTTL key capabilities:
- Material Properties Testing
One of the HTTL staff's primary tasks is to test materials used in nuclear reactor core and support structures. Researchers use several methods to measure material properties, including laser flash thermal diffusivity, pushrod dilatometry, and differential scanning calorimetry systems at the HTTL. This multi-purpose lab is equipped with high-temperature furnaces (capable of heating to 3000 °C) and autoclaves, which allow researchers to obtain high-temperature properties for existing and advanced Light Water Reactor (LWR) materials and to test potential coatings for specific LWR components. In addition, material property measurement systems provide staff comparison data from in-pile sensors being developed at HTTL.
- Specialized Instrumentation Development and Testing
The HTTL staff designs, develops, and evaluates specialized high-temperature sensors for nuclear and non-nuclear applications, including new methods for measuring temperature, thermal conductivity, and deformation in nuclear materials and test reactors. HTTL houses specialized equipment to support that work, including high-temperature tube furnaces, a high-temperature vacuum furnace, swagers, a draw bench, a laser welder, a helium leak detector system, a real time X-ray imaging system, and various high-temperature material property measurement systems to provide comparison data. Several customers are now using HTTL-designed sensors for nuclear and non-nuclear high temperature applications. HTTL's efforts also support key INL initiatives that require specialized in-pile sensors for fuels and materials irradiations, such as the Advanced Test Reactor National Scientific User Facility, the Next Generation Nuclear Plant, and the Advanced Fuel Cycle Research & Development.
- Severe Accident Testing and Consulting
The HTTL staff has long studied severe accidents that occur in nuclear reactors to determine their cause and how to prevent them. The lab is certified to test a wide range of nuclear reactor fuel and structural materials, including depleted uranium dioxide, thorium dioxide, zirconium dioxide and zirconium. Materials are tested in a stainless steel enclosure that allows off-gases to be filtered through a dedicated ventilation system with a High Efficiency Particulate Absorption filter and a Continuous Air Monitor. HTTL-developed heaters with industrial DC power supplies that can be used to heat core materials until molten and maintain them in that state in either steam of gas environments. HTTL staff uses various sensors, including one- and two-color optical pyrometers, specialized thermocouples, and gas flowrate meters, to monitor such tests. They have performed complex severe accident tests with prototypic materials found in LWRs for the Japanese Nuclear Power Engineering Corporation and in collaboration with the Seoul National University, Pennsylvania State University, and the Korea Atomic Energy Research Institute. HTTL researchers also have developed several Nuclear Regulatory Commission-funded computational tools to glean insights about the potential for steam-generator tube ruptures, in-vessel retention, and vessel lower head failure. They currently provide training to the NRC and other international research organizations and consult with vendors seeking certification for advanced reactor designs.