Developing and Evaluating Candidate Materials for Generation IV Supercritical Water Reactors - Final Technical Report, INERI 2003-008-K

Abstract

The Generation IV Supercritical Water Reactor (GEN IV SCWR) is being proposed as an advanced high efficiency thermal reactor for baseload electricity production. One of the major unknowns with this reactor concept is the behavior of fuel cladding and structural components under the extremely aggressive SCWR environment. The objective of this project was to evaluate candidate materials for SCWR application. The path the project has taken is to first determine the most likely candidate materials by surveying the literature in three principle areas; existing supercritical water fossil plants (SCFP), commercial light-water reactors (LWR) and DOE research programs in liquid-metal-fast-breeder (LMFBR) and fusion reactors. The work then entailed efforts to evaluate candidate alloys in terms of high temperature mechanical properties, corrosion and stress corrosion cracking, radiation stability. As the diagram in Figure 1 below depicts, the qualification testing was designed to provide a better understanding of likely degradation processes, aiding in the development of potential mitigation strategies. Two anticipated outcomes of the project are the production of information that can ultimately be used by SCWR system designers and guidance for future investigations involving in-reactor irradiation experiments. Identify candidate materials from fossil, LWR, and LMFBR experience Perform qualification testing on selected candidate materials Develop understanding of life-limiting materials degradation processes Investigate degradation mitigation strategies Provide initial set of materials recommendations and guidance for future in-reactor testing Year 1 Year 2 & 3 Year 3 Identify candidate materials from fossil, LWR, and LMFBR experience Perform qualification testing on selected candidate materials Develop understanding of life-limiting materials degradation processes Investigate degradation mitigation strategies Develop understanding of life-limiting materials degradation processes Investigate degradation mitigation strategies Provide initial set of materials recommendations and guidance for future in-reactor testing Year 1 Year 2 & 3 Year 3 Figure 1 Chart of project objectives and research progress. vii Research Progress Highlights of Literature Survey The literature survey was completed in the first half of year 1, and candidate materials were selected. As part of this effort, the areas where particular information gaps existed were identified in order to guide selection of the qualification test matrix. Ferritic-martensitic (F-M) steels were chosen due to their extensive use in SCFP internals. In addition, one of the early generation ferritic alloys (HT-9) was tested extensively in the US LMFBR program and was shown to have extremely high swelling resistance. However, the creep strength of HT-9 is too low for application under SCWR conditions and thus it was not selected as a primary candidate alloy, although it was used in testing to establish baseline behavior on an alloy with well known radiation performance. F-M alloys...