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Conference Spotlight
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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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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.
J. G. B. Saccheri, N. E. Todreas, M. J. Driscoll
Nuclear Technology | Volume 158 | Number 3 | June 2007 | Pages 315-347
Technical Paper | Fission Reactors | doi.org/10.13182/NT07-A3845
Articles are hosted by Taylor and Francis Online.
An 8-yr core design for an epithermal, water-cooled reactor has been developed based upon assessments of nuclear reactor physics, thermal hydraulics, and economics. An integral-vessel configuration is adopted, and self-supporting wire-wrap fuel is employed for the tight lattice of the epithermal core. A streaming path is incorporated in each assembly to ensure a negative void coefficient. A whole-core simulation of the tight core with the stochastic, continuous-energy, transport code MCNP shows a negative void coefficient for the whole cycle during normal operating conditions. Analysis of in-core, flow-induced vibrations indicates that the design has a greater margin to fluid-elastic instability than a standard pressurized water reactor, allowing for higher coolant mass flux and improved safety. Enhanced flow mixing and thermal margins are also achieved, and the VIPRETM code for subchannel thermal-hydraulic analysis has been used to calculate the critical heat flux (CHF) by means of a wire-wrap CHF correlation specifically introduced in the source code. The combination of increased fuel enrichment (~14 wt% 235U, still below the proliferation-resistant limit of 20 wt% 235U), relatively low core-average discharge burnup (70 MWd/kg HM), and very long core life (8 yr) lead to high lifetime-levelized fuel cycle unit cost [in mills/kWh(electric)]. However, both operation and maintenance (O&M) and capital-related expenditures strongly benefit from the higher electric output per unit volume, which yields quite small lifetime-levelized capital and O&M unit costs for the overall plant. Financing requirements are included, and an estimate is provided for the lifetime-levelized total unit cost of the epithermal core, which is ~16% lower than that of a more open-lattice thermal spectrum core, fitting into the same core envelope and with a 4-yr lifetime.
