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A day in the life of the nuclear community
The November issue of Nuclear News is focused on the individuals who make up our nuclear community.
We invited a small group of those individuals to tell us about their day-to-day work in some of the many occupations and applications of nuclear science and technology, and they responded generously. They were ready to tell us about the part they play, together with colleagues and team members, in supplying clean energy, advancing technology, protecting safety and health, and exploring fundamental science.
In these pages, we see a community that can celebrate both those workdays that record progress moving at a steady pace and the exceptional days when a goal is reached, a briefing is delivered, a contract goes through, a discovery is made, or an unforeseen challenge is overcome.
The Nuclear News staff hopes that you enjoy meeting these members of our community—or maybe get reacquainted with friends—through their words and photos.
M. P. Sharma, A. K. Nayak
Nuclear Science and Engineering | Volume 184 | Number 2 | October 2016 | Pages 280-291
Technical Paper | dx.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.