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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.
Mei-Ya Wang, Tsung-Kuang Yeh, Hong-Ming Liu, Min Lee
Nuclear Science and Engineering | Volume 174 | Number 2 | June 2013 | Pages 179-187
Technical Paper | doi.org/10.13182/NSE12-16
Articles are hosted by Taylor and Francis Online.
Among the six types of Generation IV reactors, the supercritical water reactor (SCWR) is the only one that adopts light water as the reactor coolant. Different from the boiling, two-phase coolant in the core of a traditional boiling water reactor (BWR), the coolant in an SCWR would remain in one phase throughout the entire primary coolant circuit (PCC) due to its much higher operating temperature (>374°C) and pressure (>22.1 MPa). For a conventional BWR, the coolant is relatively oxidizing due to the presence of hydrogen peroxide and oxygen, directly or indirectly produced via water radiolysis. This outcome eventually leads to degradation of structural materials, primarily stress corrosion cracking. In an SCWR, the solubility of oxygen in the reactor coolant is extremely high. In the absence of the gas stripping effect in a single-phase coolant, worse degradation phenomena are expected to appear in the structural and core components. To ensure proper designs of the structural components and suitable selection of the materials to meet the requirements of operation safety, it would be of great assistance to the design engineers of an SCWR to be aware of the intrinsic state of water chemistry in the entire PCC. Since SCWRs are still at the stage of conceptual design and no practical data are available, a computer model was developed for determining the water chemistry variation and the corrosion behavior of metallic materials in the PCC of a conceptual SCWR. Radiolysis parameters used for calculating the concentrations of major redox species (i.e., [O2], [H2], and [H2O2]) in the reactor coolant were collected from literature reports. However, the lack of sufficient data necessitated that some were derived by extrapolation. Calculations indicated that the concentrations of the two major oxidizing species (H2O2 and O2) could become extremely high at locations inside or near the core, considerably higher than those in typical BWRs. It was therefore speculated that the structural materials in an SCWR may be exposed to an environment not only at a much higher temperature but also one that is more oxidizing than that in a conventional BWR.
