PNNL

Nuclear power provides nearly 20 percent of the nation’s electricity. Nuclear fuel generates power for about six years, after which the spent nuclear fuel (SNF) rods are moved from the reactor into a pool of cooling water. Once the SNF has cooled sufficiently, it’s ready to be moved to long-term storage.

A permanent SNF disposal facility has yet to be designated. In the meantime, PNNL researchers are part of a team investigating potential risks posed to SNF during normal transport—including measuring the stresses SNF might experience. Supported by the U.S. Department of Energy’s Spent Fuel and Waste Science and Technology program, they recently completed a major milestone: an international journey to gauge mechanical loads (strain and vibration) on various system components.

Moving Parts

Starting in Spain, a test cask containing simulated SNF rods and assemblies (described in a previous highlight) gathered data over 9,548 miles of travel. During transport by truck, ship, and rail, and transfer by crane from each mode to the next, triaxial accelerometers and strain gauges inside and outside the equipment collected 512 to 10,000 data points every second. Measurements were recorded during the following activities:

• Nine cask-handling tests at the Equipos Nucleares (ENSA) facility in Maliaño, Spain
• Driving 395 kilometers by heavy-haul truck on roads in northern Spain
• Transport to the port of Santander on Spain’s northern coast
• Transfer to a roll-on/roll-off (Ro/Ro) vehicle, then shipment on a Ro/Ro cargo vessel to Zeebrugge, Belgium
• Sailing on a cargo ship across the Atlantic to Baltimore, Maryland.
• Transfer to a railcar for a cross-country trip to the Association of American Railroads’ Transportation Technology Center (TTCI) near Pueblo, Colorado
• Testing on TTCI's tracks, where measurements could be made under conditions replicating real-world track (e.g., grade crossings) over the same section of track at different speeds
• Return by railcar as far as St. Louis, Missouri.

Supporting Safe Shipment

In all, the data acquisition system collected nearly 6 terabytes of data. These results will be used to quantify the loads on surrogate fuel and then to estimate the loads on actual spent fuel. This will deepen our understanding of the risks of damage to SNF during future handling and transport.

The data can also be used to inform Nuclear Regulatory Commission regulations on the transport of SNF, and industry can use the data to better understand the performance of storage and transportation casks.

The international team includes PNNL, Sandia National Laboratories, Equipos Nucleares, S.A. (ENSA) and ENRESA (Empresa Nacional de Residuos Radiactivos, S.A.) of Spain, Transportation Technology Center, Inc., Korea Radioactive Waste Agency, Korea Atomic Energy Research Institute, and KEPCO Nuclear Fuel.