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The division was organized to promote the advancement of knowledge of the use of particle accelerator technologies for nuclear and other applications. It focuses on production of neutrons and other particles, utilization of these particles for scientific or industrial purposes, such as the production or destruction of radionuclides significant to energy, medicine, defense or other endeavors, as well as imaging and diagnostics.
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Maintaining RIPB in commercial LWRs
The new standard ANSI/ANS-30.3-2022, Light Water Reactor Risk-Informed, Performance-Based Design, has just been issued by the American Nuclear Society. Approved by the American National Standards Institute (ANSI) on July 21, 2022, the standard provides requirements for the incorporation of risk-informed, performance-based (RIPB) principles and methods into the nuclear safety design of commercial light water reactors. The process described in this standard establishes a minimum set of process requirements the designer must follow in order to meet the intent of this standard and appropriately combine deterministic, probabilistic, and performance-based methods during design development.
Raymond K. Maynard, Tushar K. Ghosh, Robert V. Tompson, Dabir S. Viswanath, Sudarshan K. Loyalka
Nuclear Technology | Volume 172 | Number 1 | October 2010 | Pages 88-100
Technical Paper | Materials for Nuclear Systems | dx.doi.org/10.13182/NT10-6
Articles are hosted by Taylor and Francis Online.
An experimental system was constructed in accordance with the standard ASTM C835-06 to measure the total hemispherical emittance (emissivity) of structural materials of interest in very high temperature reactor (VHTR) systems. First, data were acquired for 304 stainless steel as well as for oxidized and unoxidized nickel, and good reproducibility and agreement with the literature was found. Emissivity of Hastelloy X was then measured under different conditions that included (a) "as received" (original sample) from the supplier, (b) with increased surface roughness, (c) oxidized, and (d) graphite coated. Measurements were made over a wide range of temperatures. Hastelloy X, as received from the supplier, was cleaned before additional roughening of the surface and coating with graphite. The emissivity of the original samples (cleaned after received) varied from [approximately]0.18 to 0.28 in the temperature range of 473 to 1498 K. The apparent emissivity increased only slightly as the roughness of the surface increased (without corrections for the increased surface area due to the increased surface roughness). When Hastelloy X was coated with graphite or was oxidized, however, its emissivity was observed to increase substantially. With a deposited graphite layer on the Hastelloy, increases from 0.2 to 0.53 at 473 K and from 0.25 to 0.6 at 1473 K were observed - a finding that has strong favorable safety implications in terms of decay heat removal in postaccident VHTR environments. Initial oxidation of Hastelloy X surfaces was observed to notably increase the emissivity of the Hastelloy X but was not observed to progress significantly beyond the initial oxidation even with more prolonged exposure. Since there is likely to be initial surface oxidation of any Hastelloy X used in the construction of VHTRs, this represents an essentially neutral finding in terms of the safety implications in postaccident VHTR environments.