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Transient Response to Rapid Cooling of a Stainless Steel Sodium Heat PipeCompact fission power systems are under consideration for use in long duration space exploration missions. Power demands on the order of 500 W, to 5 kW, will be required for up to 15 years of continuous service. One such small reactor design consists of a fast spectrum reactor cooled with an array of in-core alkali metal heat pipes coupled to thermoelectric or Stirling power conversion systems. Heat pipes advantageous attributes include a simplistic design, lack of moving parts, and well understood behavior. Concerns over reactor transients induced by heat pipe instability as a function of extreme thermal transients require experimental investigations. One particular concern is rapid cooling of the heat pipe condenser that would propagate to cool the evaporator. Rapid cooling of the reactor core beyond acceptable design limits could possibly induce unintended reactor control issues. This paper discusses a series of experimental demonstrations where a heat pipe operating at near prototypic conditions experienced rapid cooling of the condenser. The condenser section of a stainless steel sodium heat pipe was enclosed within a heat exchanger. The heat pipe - heat exchanger assembly was housed within a vacuum chamber held at a pressure of 50 Torr of helium. The heat pipe was brought to steady state operating conditions using graphite resistance heaters then cooled by a high flow of gaseous nitrogen through the heat exchanger. Subsequent thermal transient behavior was characterized by performing an energy balance using temperature, pressure and flow rate data obtained throughout the tests. Results indicate the degree of temperature change that results from a rapid cooling scenario will not significantly influence thermal stability of an operating heat pipe, even under extreme condenser cooling conditions.
Document ID
20110008814
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Mireles, Omar R.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Houts, Michael G.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 25, 2013
Publication Date
February 7, 2011
Subject Category
Energy Production And Conversion
Report/Patent Number
M11-0088
Meeting Information
Meeting: Nuclear and Emerging Technologies for Space 2011
Location: Albuquerque, NM
Country: United States
Start Date: February 7, 2011
End Date: February 10, 2011
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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