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Division Spotlight
Operations & Power
Members focus on the dissemination of knowledge and information in the area of power reactors with particular application to the production of electric power and process heat. The division sponsors meetings on the coverage of applied nuclear science and engineering as related to power plants, non-power reactors, and other nuclear facilities. It encourages and assists with the dissemination of knowledge pertinent to the safe and efficient operation of nuclear facilities through professional staff development, information exchange, and supporting the generation of viable solutions to current issues.
Meeting Spotlight
Utility Working Conference and Vendor Technology Expo (UWC 2024)
August 4–7, 2024
Marco Island, FL|JW Marriott Marco Island
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Nuclear Science and Engineering
August 2024
Nuclear Technology
Fusion Science and Technology
Latest News
ARPA-E announces $40 million to develop transmutation technologies for UNF
The Department of Energy’s Advanced Research Projects Agency–Energy (ARPA-E) announced $40 million in funding to develop cutting-edge technologies to enable the transmutation of used nuclear fuel into less-radioactive substances. According to ARPA-E, the new initiative addresses one of the agency’s core goals as outlined by Congress: to provide transformative solutions to improve the management, cleanup, and disposal of radioactive waste and spent nuclear fuel.
F. Zhou, D. R. Novog, L. J. Siefken, C. M. Allison
Nuclear Science and Engineering | Volume 190 | Number 3 | June 2018 | Pages 209-237
Technical Paper | doi.org/10.1080/00295639.2018.1442060
Articles are hosted by Taylor and Francis Online.
In different stages of postulated severe accidents in CANDU reactors, the fuel channels may experience a series of thermomechanical deformations, some of which may have significant impacts on accident progression; however, they have not been mechanistically modeled by integrated severe accident codes such as MAAP-CANDU and SCDAP/RELAP5. This paper focuses on the development and benchmarking of mechanistic models for pressure tube (PT) ballooning and sagging phenomena during the fuel channel heatup phase as well as for the sagging of fuel channel assemblies during the core disassembly phase. These models, which are based on existing phenomena in literature, are coupled with RELAP5 and/or integrated into RELAP/SCDAPSIM/MOD3.6 as new SCDAP subroutines to provide more robust treatment of the deformation phases of severe accidents.
The ballooning of a PT will lead to contact with its calandria tube (CT) and occurs during conditions where the coolant pressure is moderately high. At initial contact the high contact thermal conductance and the large temperature difference between the two tubes result in a large transient heat flux that challenges the channel integrity through potential film boiling on the outer calandria surface if moderator subcooling is low. A one-dimensional ballooning and contact model (BALLON) has been developed. BALLON calculates the ballooning-driven transverse strain of PT and CT and modifies the effective conductivity of the annulus before and after contact.
Pressure tube sagging is the dominant deformation mechanism at low pressures and occurs at relatively high PT temperatures. A model based on simple beam theory (SAGPT) has been developed. SAGPT calculates the longitudinal strain and the deflection of PT, and it also determines PT-to-CT sagging contact. The sagging and disassembly of the entire fuel channel assembly occur when the fuel channels are uncovered and the moderator heat sink is lost; thus, the entire PT-CT assembly sags together, possibly contacting channels at lower elevations. A model named SAGCH is created to track fuel channel assembly sagging after moderator boil off and also determines the extent of channel-to-channel contact, channel disassembly, suspended debris bed characteristics, and eventual core collapse.
This paper presents detailed descriptions of the models, the coupling schemes, and their benchmark against experiments, together with an extensive review of relevant studies in the literature.