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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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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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Deep Space: The new frontier of radiation controls
In commercial nuclear power, there has always been a deliberate tension between the regulator and the utility owner. The regulator fundamentally exists to protect the worker, and the utility, to make a profit. It is a win-win balance.
From the U.S. nuclear industry has emerged a brilliantly successful occupational nuclear safety record—largely the result of an ALARA (as low as reasonably achievable) process that has driven exposure rates down to what only a decade ago would have been considered unthinkable. In the U.S. nuclear industry, the system has accomplished an excellent, nearly seamless process that succeeds to the benefit of both employee and utility owner.
Üner Çolak, Volkan Seker
Nuclear Science and Engineering | Volume 149 | Number 2 | February 2005 | Pages 131-137
Technical Paper | doi.org/10.13182/NSE04-17
Articles are hosted by Taylor and Francis Online.
In this study, the criticality analysis for a pebble bed reactor, HTR-10, is performed with Monte Carlo simulations. The MCNP4B code package is utilized in the analysis with ENDF/B-VI continuous energy cross sections. The full core with the initial loading case is considered in simulations. The variation of the effective multiplication factor as a function of core loading height is also analyzed. Three different geometrical models are employed to see the effect of geometrical detail on the criticality calculations. Results are compared with diffusion calculations as well as the experimental data. Results show that the use of the homogenized fuel zone model does not yield acceptable results and underestimates the core criticality. However, the results obtained by using models with uniform and randomly distributed coated fuel particles in the fuel zone are in quite good agreement and there is not any systematic difference. Furthermore, criticality values do not change significantly with different random arrangements of coated fuel particles in fuel spheres. However, the random and irregular arrangements of pebbles may result in statistically different criticality values at least due to varying streaming effect.
