Thermal-Hydraulic Analyses of the Submersion-Subcritical Safe Space (S⁴) Reactor


Detailed thermal-hydraulic analyses of the S[logical and]4 reactor are performed to reduce the maximum fuel temperature of the Submersion-Subcritical Safe Space (S[logical and]4) reactor to below 1300 K. The fuel pellet diameter is reduced from 1.315 cm to 1.25 cm, decreasing the thermal resistance of the pellets and each of the 1.54 cm diameter coolant channels in the reactor core are replaced with several 0.3 cm ID channels to increase the effective heat transfer area and to encourage mixing of the flowing helium-28% xenon coolant. The calculated maximum fuel temperature decreased from more than 1900 K to 1302 K and the relative pressure drop across the reactor core increased from 1.98% to 2.57% of the inlet pressure. Moving the concentric inlet and outlet pipes 1 cm towards the center of the reactor core encouraged more flow through the center region, further reducing the maximum fuel temperature by 14 degrees to 1288 K, with a negligible effect on the core pressure losses.


Nuclear Engineering and Radiation Science

Keywords and Phrases

Fission Reactor Collants; Fission Reactor Design; Power Systems; Space Vehicles

Document Type

Article - Conference proceedings

Document Version


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© 2007 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 Jan 2007