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Division Spotlight
Materials Science & Technology
The objectives of MSTD are: promote the advancement of materials science in Nuclear Science Technology; support the multidisciplines which constitute it; encourage research by providing a forum for the presentation, exchange, and documentation of relevant information; promote the interaction and communication among its members; and recognize and reward its members for significant contributions to the field of materials science in nuclear technology.
Meeting Spotlight
International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
Standards Program
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
Argonne’s METL gears up to test more sodium fast reactor components
Argonne National Laboratory has successfully swapped out an aging cold trap in the sodium test loop called METL (Mechanisms Engineering Test Loop), the Department of Energy announced April 23. The upgrade is the first of its kind in the United States in more than 30 years, according to the DOE, and will help test components and operations for the sodium-cooled fast reactors being developed now.
Fei-Jan Tsai, Min Lee
Nuclear Technology | Volume 205 | Number 4 | April 2019 | Pages 524-541
Technical Paper | doi.org/10.1080/00295450.2018.1500831
Articles are hosted by Taylor and Francis Online.
This study assessed the effectiveness of in-vessel retention (IVR) in terminating the progression of an accident sequence initiated by a station blackout and large loss-of-coolant accident in a pressurized water reactor with thermal power of approximately 5000 MW. In the IVR design, external reactor vessel cooling is established by flooding of the reactor cavity. A water channel is introduced into the outer wall of the reactor vessel, and an insulated layered structure is added around the vessel. The amount of heat removed from the corium pool in the vessel lower plenum is limited by the critical heat flux (CHF) at the outer surface of the vessel wall. An integrated assessment was conducted in three steps. First, the responses of the reactor coolant system and containment were simulated using MELCOR. The predicted transient heat load at the vessel wall was then fed into RELAP5-3D, where the flow of natural, buoyancy-driven convection within the IVR water channel was simulated. Finally, the main thermal-hydraulic parameters in the IVR channel were substituted into the ULPU, SULTAN, SBLB, and MELCOR CHF correlations, and the effectiveness of IVR was assessed. The MELCOR simulation demonstrated that the heat load at the vessel wall of the lower plenum is dependent on the configuration of the debris. The heat flux to the vessel wall reached a maximum at 483 min, at an inclination angle of approximately 68 deg. The peak heat flux moved from a small inclination angle to a larger angle as the accident progressed. Both MELCOR and RELAP5-3D calculations predicted a gradual buildup of natural convection flow within the IVR channel following the application of a heat load to the vessel wall. The MELCOR code significantly overpredicts the mass flow of natural convection flow. Both codes predicted that the flow would experience large-amplitude fluctuations as the water in the IVR flow channel reached saturation. These fluctuations were attributed to instability induced by two-phase flow.
If the inlet temperature can be kept sufficiently low to obviate boiling in the IVR channel, RELAP5-3D predicts that the channel flow will approach an approximately steady state. The selected CHF correlations predicted significantly different CHFs. The MELCOR correlation, which is a correlation based on pool boiling, produced the most conservative predictions, and the CHFs predicted by SBLB had the highest value. The minimum margin was found between 55 and 75 deg in all correlations. With the exception of the MELCOR correlation, the CHF ratio predicted by the other three correlations is greater than 1.2.