Evaluation of Aluminum-Boron Carbide Neutron Absorbing Materials for Interim Storage of Used Nuclear Fuel

Technical Report · Wed Apr 08 00:00:00 EDT 2015

DOI:https://doi.org/10.2172/1178572· OSTI ID:1178572

Wang, Lumin ^[1]; Wierschke, Jonathan Brett ^[1]

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1. Univ. of Michigan, Ann Arbor, MI (United States). Department of Nuclear Engineering and Radiological Science

The objective of this work was to understand the corrosion behavior of Boral® and Bortec® neutron absorbers over long-term deployment in a used nuclear fuel dry cask storage environment. Corrosion effects were accelerated by flowing humidified argon through an autoclave at temperatures up to 570°C. Test results show little corrosion of the aluminum matrix but that boron is leaching out of the samples. Initial tests performed at 400 and 570°C were hampered by reduced flow caused by the rapid build-up of solid deposits in the outlet lines. Analysis of the deposits by XRD shows that the deposits are comprised of boron trioxide and sassolite (H₃BO₃). The collection of boron- containing compounds in the outlet lines indicated that boron was being released from the samples. Observation of the exposed samples using SEM and optical microscopy show the growth of new phases in the samples. These phases were most prominent in Bortec® samples exposed at 570°C. Samples of Boral® exposed at 570°C showed minimal new phase formation but showed nearly the complete loss of boron carbide particles. Boron carbide loss was also significant in Boral samples at 400°C. However, at 400°C phases similar to those found in Bortec® were observed. The rapid loss of the boron carbide particles in the Boral® is suspected to inhibit the formation of the new secondary phases. However, Material samples in an actual dry cask environment would be exposed to temperatures closer to 300°C and less water than the lowest test. The results from this study conclude that at the temperature and humidity levels present in a dry cask environment, corrosion and boron leaching will have no effect on the performance of Boral® and Bortec® to maintain criticality control.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE). Nuclear Energy University Programs (NEUP)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1178572
• Report Number(s): DOE/NEUP-10-961; 10-961; TRN: US1500357
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BORON CARBIDES
SPENT FUEL STORAGE
BORON
ALUMINIUM
CORROSION
CASKS
X-RAY DIFFRACTION
SCANNING ELECTRON MICROSCOPY
ARGON
BORIC ACID
BORON OXIDES
LEACHING
DEPOSITS
LOSSES
OPTICAL MICROSCOPY
EVALUATION
HUMIDITY
PARTICLES
NEUTRON ABSORBERS
CONTROL
CRITICALITY
MATRIX MATERIALS
PERFORMANCE
DRY STORAGE
TEMPERATURE RANGE 0400-1000 K
PHASE STUDIES