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Division Spotlight
Decommissioning & Environmental Sciences
The mission of the Decommissioning and Environmental Sciences (DES) Division is to promote the development and use of those skills and technologies associated with the use of nuclear energy and the optimal management and stewardship of the environment, sustainable development, decommissioning, remediation, reutilization, and long-term surveillance and maintenance of nuclear-related installations, and sites. The target audience for this effort is the membership of the Division, the Society, and the public at large.
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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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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.
M. P. Sharma, A. K. Nayak
Nuclear Science and Engineering | Volume 184 | Number 2 | October 2016 | Pages 280-291
Technical Paper | doi.org/10.13182/NSE15-112
Articles are hosted by Taylor and Francis Online.
The Advanced Heavy Water Reactor (AHWR) is a vertical pressure tube–type, heavy water–moderated and boiling light water–cooled natural circulation–based reactor. The fuel bundle of an AHWR contains 54 fuel rods arranged in three concentric rings of 12, 18, and 24 fuel rods. This fuel bundle is divided into a number of imaginary interacting flow passages called subchannels. The transition from single-phase to two-phase flow occurs in a reactor rod bundle with an increase in power. Two-phase flow regimes like bubbly, slug/churn, and annular flow are normally encountered in a reactor rod bundle. Prediction of the thermal margin of the reactor necessitates the determination of the turbulent-mixing rate of the coolant among these subchannels under these flow regimes. Thus, it is vital to evaluate turbulent mixing between the subchannels of an AHWR rod bundle.
In this paper, experiments were carried out to determine the two-phase turbulent-mixing rate in different flow regimes in the simulated subchannels of the reactor. The size of the rod and the pitch in the test were the same as those of an actual rod bundle in the prototype. Three subchannels are considered in 1/12th of the cross section of the rod bundle. Water and air were used as the working fluid, and the turbulent-mixing tests were carried out at atmospheric conditions without addition of heat. The void fraction was varied from 0 to 0.8 under various ranges of superficial liquid velocity. The turbulent-mixing rate was experimentally determined by adding tracer fluid in one subchannel and measuring its concentration in other subchannels at the end of the flow path. The test data were compared with existing models in the literature. It was found that none of the models could predict the measured turbulent-mixing rate in the rod bundle of the reactor.