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NRC looks to leverage previous approvals for large LWRs
During this time of resurging interest in nuclear power, many conversations have centered on one fundamental problem: Electricity is needed now, but nuclear projects (in recent decades) have taken many years to get permitted and built.
In the past few years, a bevy of new strategies have been pursued to fix this problem. Workforce programs that seek to laterally transition skilled people from other industries, plans to reuse the transmission infrastructure at shuttered coal sites, efforts to restart plants like Palisades or Duane Arnold, new reactor designs that build on the legacy of research done in the early days of atomic power—all of these plans share a common throughline: leveraging work already done instead of starting over from square one to get new plants designed and built.
R. L. Crowther, J. W. Weil
Nuclear Science and Engineering | Volume 3 | Number 6 | June 1958 | Pages 747-757
Technical Paper | doi.org/10.13182/NSE58-A25508
Articles are hosted by Taylor and Francis Online.
The presence of a large, sharp resonance at 1 ev in Pu240 results in the effective pile cross section for this isotope being very much larger than the true thermal cross section. Furthermore, the narrowness of this resonance causes the absorption of epithermal neutrons in Pu240 to be strongly self-shielded. Consequently, the effective cross section of Pu240 will be a function of reactor spectrum and of the Pu240 concentration at any given time. The significance of this effect can be appreciated by noting that the effective cross section of this isotope is frequently more than twice the effective thermal value. An approximate method of calculation has been applied to long term reactivity problems. The importance of the resonance augmentation and concentration dependence of the Pu240 cross section is particularly evident in the first few thousand Mwd/t and causes significant changes in the reactivity required to reach any longer burnout. Sample calculations are presented and comparisons with the Canadian experimental determinations of the effective Pu240 cross section are made. An effective constant Pu240 cross section is presented which will yield approximately correct burnout results when used in conventional irradiation studies.
