Commercial boiling water reactors are implemented as a way to provide energy in a clean and efficient manner.  These reactors have been in use for years however information regarding fuel rods and their behavior in these extreme environments have not been studied in depth.  This presents a need for a test bench that allows the ability of fuel rods of differing properties to be studied under these conditions.  The INL facilities have expressed a desire and shown a need to fully understand the behavior of the fuel rods throughout their life to failure.  A BWTL provides a test bench that recreates the environment seen in a commercial boiling water reactor and allows  for a full examination of the life cycle of fuel rods and their surroundings. 

Provisional BWTL
Figure 1.  Process flow diagram for provisional BWTL auxiliary loop
provided by S. St. Germain and K. Steuhm

The achievability of this project was analyzed, taking into consideration cost, experience, and time. In order to make the most of available resources, a simpler BWTL was proposed that would have lower temperature and pressure operating points. The main advantage of operating at lower conditions is that “off the shelf” products can be used. This simplified BWTL will contain the majority of the same features and will enable a thermodynamic cycle, similar to the one used in the full size loop.
The simplified loop has been designed for the purpose of providing a test bench to verify the boiling regime and heat transfer coefficients in the test section. In addition, the system will be useful for the testing of instrumentation and control systems.
Listed in the table below are the design requirements for the system:
Scaled BWTL Specs

In addition to the specifications listed above, below is a process flow diagram for the scaled test bench.  Included in the diagram are the desired conditions for boiling verification and components critical to project realization.  These components include a cartridge heater, clear test section, line heater, pump, expansion tank, and heat exchanger.  Each of these components are essential to creating a scaled version of the conditions seen in a commercial boiling water reactor.

Scaled BWTL Flow DiagramFigure 2.  Process flow diagram for proposed BWTL system showing critical components to satisfy desired system conditions.

*Note: The placement for the sensors are not final. When more information has been collected for the control system, a more accurate diagram with the placement of the sensors will be made.

What is a BWTL?

Boiling water test loops are used to research the behavior  of materials in the same conditions seen in a  boiling water nuclear reactor.  This will be done  by creating a closed loop that will circulate water at the same state as seen in a reactor.

Important dates:

Detailed Design Package   Jan. 29
Parts Ordered                   Feb. 5
Loop Built                         Apr. 9
Finish Testing                  May 7
 University of IdahoIdaho National Laboratory