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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.
Heba K. Louis
Nuclear Technology | Volume 188 | Number 1 | October 2014 | Pages 1-7
Technical Paper | Fission Reactors | doi.org/10.13182/NT13-120
Articles are hosted by Taylor and Francis Online.
The lifetime of prompt neutrons is a basic characteristic of reactors since it determines the neutron kinetics of the reactor in all transient processes. This paper focuses on calculation of the prompt neutron lifetime for pressurized water reactors (PWRs). The calculation was performed using two independent methods. The first method uses the fundamental definition of the neutron lifetime with adjoint weighting that has recently been included in MCNPX. The second method is the 1/v absorber insertion method, where a 1/v absorber such as 10B is placed uniformly throughout a nuclear reactor and the change in reactivity is calculated. This prompt neutron lifetime is then extracted from the changes in the reactivity as the 10B concentration approaches zero. The results of the two methods are compared together at two points in the operation cycle [at beginning of cycle (BOC) and at end of cycle (EOC)]. The values of the prompt neutron lifetime as calculated with MCNPX are compared to values calculated with another independent method, and the results are in reasonable agreement with each other. Also, these results compared with the PWR final safety analysis report show good agreement. In the two methods of calculation, the prompt neutron lifetime was determined to be longer at EOC when compared to that at BOC.
