The Global Threat Reduction Initiative (GTRI) is a National Nuclear Security Administration (NNSA) nonproliferation program which aims to convert research reactors from the use of highly enriched uranium (HEU) to low enriched Uranium (LEU). Oregon State University is contracted by the Idaho National Laboratory to aid in the qualification of an ultra-high density Uranium-Molybdenum fuel for use in these reactors. As part of this project, the Endurance Flow Loop will study the long-term effects of the in-pile conditions on the fuel elements over the cycle length of the reactor, which is about one year

The Endurance Flow Loop (EFL) is a parallel system welded stainless steel flow loop designed to force a controlled volumetric rate of water over mock-up reactor fuel plates to simulate in-pile hydraulic conditions. Although compact in size, the EFL is outfitted with a number of different flow paths balanced by strategically placed valves to divert flow in the necessary manner to achieve desired flow and pressure conditions over the fuel elements. All hardware and sensors on the EFL are controlled or monitored through a Data Acquisition System (DAS) and displayed in a Graphical User Interface (GUI) control panel on the computer.

The driving force for the flow in the EFL is the twin-stage 10-hp vertical in-line pump that can deliver 35-225 GPM and can provide a differential pressure of up to 200 ft. dynamic head. This pump is controlled via a Variable Speed Drive (VSD) which adjusts the rotational speed of the pump. Flow through the EFL is measured from three vortex-style Rosemount flowmeters, which cover the whole operational range of the system. Pressure transmitters are placed around the facility to monitor the gage pressure of the inlet test sections, and the differential pressure across the fuel elements, and across the pump. Three thermocouples are located on the facility to measure the bulk coolant temperature and the differential temperature across the pump. Water quality is measured from the PH and Conductivity probes.


The Endurance Flow Loop
The EFL (left) and one of two test sections (right) in the LIFT Laboratory.


measured flow in the EFL

Measured flow versus pressure drop.