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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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April 27–30, 2025
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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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Latest News
TerraPower begins U.K. regulatory approval process
Seattle-based TerraPower signaled its interest this week in building its Natrium small modular reactor in the United Kingdom, the company announced.
TerraPower sent a letter to the U.K.’s Department for Energy Security and Net Zero, formally establishing its intention to enter the U.K. generic design assessment (GDA) process. This is TerraPower’s first step in deployment of its Natrium technology—a 345-MW sodium fast reactor coupled with a molten salt energy storage unit—on the international stage.
R.R. Parker, the ITER Joint Central Team
Fusion Science and Technology | Volume 26 | Number 3 | November 1994 | Pages 273-283
International Thermonuclear Experimental Reactor (ITER) | Proceedings of the Eleventh Topical Meeting on the Technology of Fusion Energy New Orleans, Louisiana June 19-23, 1994 | doi.org/10.13182/FST94-A40175
Articles are hosted by Taylor and Francis Online.
The Engineering Design Activities (EDA) for the International Thermonuclear Experimental Reactor (ITER) are now entering their third year, and an Outline Design has been developed which includes specifications of the important machine parameters and conceptual designs for the major device subsystems. Prospects for reaching ignition are good, as an H-mode factor of only 1.3 is required. However, producing a sustained burn, as will be necessary for the testing program, depends on the steady-state helium level, which in turn depends on core particle transport and the efficiency of helium removal in the divertor. A steady-state helium level of 15% requires an H-mode factor of 2 for sustained ignition. A new concept for the divertor has been developed which relies mainly on removal of the power by radiation. Divertor modeling efforts show that power removal by charge exchange (CX) is ineffective for scrape-off layer densities and connection lengths expected in ITER. However, CX remains an important mechanism for momentum removal. While removal of power in the divertor channel is the reference mode of operation, flexibility is incorporated into the design by permitting the bulk of the power also to be radiated to the first wall. The main concept for the first wall and blanket/shield systems is an integrated one, where the first wall also forms a structural boundary of the blanket. An alternative design in which the functions are separate is also being developed. Both approaches satisfy the main design requirements, specifically a first wall heat flux of 0.5 MW/m2 and a shielding performance adequate to permit rewelding of the vacuum vessel. The latter is a double-walled structure, typically 40–70 cm thick, filled with steel balls which are directly cooled by relatively low temperature (∼150°C) water. Inconel 625 is the reference structural material for the vessel, with stainless steel (316L) as a backup. Although more straightforward in concept than the divertor and blanket, the vacuum vessel is a primary safety barrier and must be designed to rigorous standards. The auxiliary heating requirements for ITER are met by a baseline design of 50 MW of RF power provided by ICRF heating. Both NBI and ECH heating systems are being developed as design options. These systems have advantages over ICRF in the degree to which they require integration with the first wall and blanket/shield systems. However, NBI has a greater overall impact on the design since it extends the tritium boundary outside the nominal boundary of cryostat. A decision on the selection of the heating and current drive system is expected in 1995.
