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The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
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2024 ANS Annual Conference
June 16–19, 2024
Las Vegas, NV|Mandalay Bay Resort and Casino
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Latest News
Framatome signs contracts with Sizewell C
French nuclear developer Framatome is slated to deliver key equipment for Sizewell C Ltd.’s two large reactors planned for the United Kingdom’s Suffolk coast.
The agreement, reportedly worth multiple billions of euros, was announced this week and will involve Framatome from the design phase until commissioning. The company also agreed to a long-term fuel supply deal. Framatome is 80.5 percent owned by France’s EDF and 19.5 percent owned by Mitsubishi Heavy Industries.
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.