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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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2024 ANS Winter Conference and Expo
November 17–21, 2024
Orlando, FL|Renaissance Orlando at SeaWorld
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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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New laws offer nuclear industry incentives for existing power plant uprates
This year, the U.S. nuclear industry received a much-needed economic boost that could help preserve operating nuclear power plants and incentivize upgrades that extend their lifespan and power output.
Signed into law in 2022, the Inflation Reduction Act offers production tax credits (PTCs) for existing nuclear power plants and either PTCs or investment tax credits (ITCs) for new carbon-free generation. These credits could make power uprates—increasing the maximum power level at which a commercial plant may operate—a much more appealing option for utilities.
B. J. Toppel
Nuclear Science and Engineering | Volume 5 | Number 2 | February 1959 | Pages 88-98
Technical Paper | doi.org/10.13182/NSE59-A25561
Articles are hosted by Taylor and Francis Online.
A common method used to determine reactivity is to measure the reactor period and then refer to the inhour equation which relates asymptotic period to reactivity. The implicit assumption in such a method is that the neutron population is varying exponentially with time. The conditions necessary for this assumption to be valid have been obtained by a quantitative examination of the time behavior of the neutron population. The results obtained show that under common experimental conditions, several minutes may be required following a positive step change in reactivity in order to achieve accuracy by means of a period determination. In addition, in the case of the reactor with a constant extraneous source, a significant increase in this waiting time can result even if the reactor is initially only very slightly subcritical. Whereas in principle both positive and negative reactivities may be obtained from period observations, it is pointed out that in practice serious objections exist for the case of negative reactivities.