Materials for High-Temperature Nuclear Reactors

Goeddel, W.V.; Siltanen, J.N.

doi:10.1146/annurev.ns.17.120167.001201

Cited by 10 publications

(1 citation statement)

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“…The mechanical or material effects resulting from these basic radiation damage mechanisms are controlled by a number of factors, including the operating temperature, the degree of crystallinity within the microstructure, the variation of crystallite orientation, and the microdamage within the formed graphitic microstructure during fabrication processes. 4 All these parameters significantly affect the thermo-mechanical response of the graphite, but temperature plays the key role in determining the effects on graphitic structures.…”

Section: Radiation Effects On Graphitementioning

confidence: 99%

Graphite Technology Development Plan

Windes¹,

Burchell²,

Bratton³

2007

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SUMMARYThe Next Generation Nuclear Plant (NGNP) will be a helium-cooled High Temperature Gas Reactor (HTGR) with a large graphite core. Graphite physically contains the fuel and comprises the majority of the core volume. Graphite has been used effectively as a structural and moderator material in both research and commercial high-temperature gas-cooled reactors. This development has resulted in graphite being established as a viable structural material for HTGRs. While the general characteristics necessary for producing nuclear grade graphite are understood, historical "nuclear" grades no longer exist. New grades must be fabricated, characterized, and irradiated to demonstrate that current grades of graphite exhibit acceptable non-irradiated and irradiated properties upon which the thermomechanical design of the structural graphite in NGNP is based. This Technology Development Plan establishes the research and development (R&D) activities and associated rationale necessary to qualify nuclear grade graphite for use within the NGNP reactor.Background information from past graphite reactor experience, other relevant graphite grades, and the state of graphite technology developed for past gas reactors is presented to provide a perspective on what has been achieved previously in this area of research. The technology required to qualify the graphite for use in NGNP is being developed based on the historical graphite fabrication and performance database, the anticipated NGNP graphite design service conditions, and gaps in the fabrication and performance database.The resultant data needs are outlined and justified from the perspective of reactor design, reactor performance, or the reactor safety case. The approach allows direct comparison between data needs and the resulting technology development activities. Because there are many variables (i.e., reactor designs, multiple graphite types, a range of operating temperatures and fluence, etc.) that can significantly affect the development of graphite technology for the NGNP, a "baseline" reactor design was chosen to simplify the identification of needed data. The prismatic HTGR design with an outlet temperature of 950°C was chosen as the baseline technology. In this case, the expected doses and operation service lifetimes are expected to be fairly moderate. Technology development needs to satisfy requirements beyond this baseline (i.e., much higher doses expected at graphite reflector surfaces facing the fuel pebbles in the pebble-bed core) are presented separately to provide a more complete understanding of the important differences in the technical requirements for prismatic and pebble-bed HTGRs.The irradiation program proposed for the prismatic HTGR design consists of eight irradiations that span the proposed temperature-dose envelope for a prismatic NGNP. These irradiations will contain specimens of sufficient size, number, and type to support statistical assessments necessary to capture the inherent variability in graphite; to support traditional American Society for...

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Section: Radiation Effects On Graphitementioning

confidence: 99%