THE NEED FOR A NEW JOINING TECHNOLOGY FOR THE CLOSURE WELDING OF RADIOACTIVE MATERIALS CONTAINERS Page: 4 of 8
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WMO9 Paper
The Need for a New Joining Technology for the
Closure Welding of Radioactive Materials Containers - 9516
G.R. Cannell, G. J Grant, Burt E. Hill
Hanford Site
P.O Box 1000, Richland, WA 99352
ABSTRACT
One of the activities associated with cleanup throughout the Department of Energy (DOE)
complex is packaging radioactive materials into storage containers. Much of this work will be
performed in high-radiation environments requiring fully remote operations, for which existing,
proven systems do not currently exist. These conditions demand a process that is capable of
producing acceptable (defect-free) welds on a consistent basis; the need to perform weld repair,
under fully-remote operations, can be extremely costly and time consuming. Current closure-
welding technology (fusion welding) is not well suited for this application and will present risk to
cleanup cost and schedule. To address this risk, Fluor and the Pacific Northwest National
Laboratory (PNNL), are proposing that a new and emerging joining technology, Friction Stir
Welding (FSW), be considered for this work.
FSW technology has been demonstrated in other industries (aerospace and marine) to produce
near flaw-free welds on a consistent basis. FSW is judged capable of providing the needed
performance for fully-remote closure welding of containers for radioactive materials for the
following reasons:
- FSW is a solid-state process; material is not melted. As such, FSW does not produce the
type of defects associated with fusion welding, e.g., solidification-induced porosity, cracking,
distortion due to weld shrinkage, and residual stress. In addition, because FSW is a low-heat
input process, material properties (mechanical, corrosion and environmental) are preserved
and not degraded as can occur with "high-heat" fusion welding processes. When compared
to fusion processes, FSW produces extremely high weld quality.
- FSW is performed using machine-tool technology. The equipment is simple and robust and
well-suited for high radiation, fully-remote operations compared to the relatively complex
equipment associated with the fusion-welding processes.
- Additionally, for standard wall thicknesses of radioactive materials containers, the FSW
process can perform final closure welding in a single pass (GTAW requires multiple passes)
resulting in increased productivity.
Together, the performance characteristics associated with FSW, i.e., high weld quality, simple
machine-tool equipment and increased welding efficiency, are expected to reduce risk to
upcoming DOE radioactive materials packaging campaigns.
FSW technology requires some development/adaptation for this application, along with approval
from the governing code of construction prior to production operations. This paper addresses the
need for a new joining technology, a description of the FSW process and why it is well-suited for
this application, and several activities required for commercialization.
INTRODUCTION
Over the past five years, the U.S. Department of Energy (DOE), Richland Operations Office
(DOE-RL), has completed several significant, radioactive materials packaging campaigns at the
Hanford Site. Included are those for packaging Special Nuclear Materials (SNM) into some 2,000
DOE-3013 containers, packaging of Spent Nuclear Fuel (SNF) into more than 400 Multi-Canister
Overpack (MCO) canisters, and overpacking of TRIGA research reactor fuel. A key element in1
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GR, CANNELL; BE, HILL & GJ, GRANT. THE NEED FOR A NEW JOINING TECHNOLOGY FOR THE CLOSURE WELDING OF RADIOACTIVE MATERIALS CONTAINERS, article, October 29, 2008; Richland, Washington. (https://digital.library.unt.edu/ark:/67531/metadc902552/m1/4/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.