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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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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.
Nicholas T. Saltos,* Richard N. Christensen, Tunc Aldemir
Nuclear Technology | Volume 83 | Number 1 | October 1988 | Pages 93-109
Technical Paper | Heat Transfer and Fluid Flow | doi.org/10.13182/NT88-A34178
Articles are hosted by Taylor and Francis Online.
A methodology is presented to determine the transient temperature distributions in fuel bundles under loss-of-coolant-accident (LOCA) conditions using a recently developed variational technique for the solution of radial-azimuthal heat conduction in the fuel rods and the modified view factor concept proposed by Uchida and Nakamura to model the radiative heat transfer between the rods. The variational technique is based on the Lebon-Labermont restricted variational principle and represents the temperature distribution in the rods at a given time during the LOCA via parabolic and circular trial functions in the radial and azimuthal directions, respectively. The methodology is implemented to a 4 × 4 boiling water reactor fuel bundle under typical LOCA conditions to investigate the effects of changes in rod heat transfer characteristics and simplifying modeling assumptions on predicted rod temperature distributions. The results show that these effects depend on the rod location in the assembly and LOCA phase under consideration and indicate that same degree of modeling detail may not be necessary for all the rods in the bundle at all times during the LOCA. An important advantage of the methodology is that it selects the optimum number of trial functions for each rod and for each time step in the simulation to reduce the computation time without compromising solution accuracy. Other advantages are that (a) the variational technique is faster than finite difference techniques for comparable accuracy and uses the same algorithm for one-dimensional radial and two-dimensional solutions, and (b) formulation of the heat conduction problem in the rods is compatible with the modular accident analysis codes already in use in the nuclear industry.
