Examples for nuclear innovation part 1: thermosiphons and heat pipes

Currently, there are numerous innovations worldwide that make nuclear technology more efficient, safer and environmentally friendly. Examples are thermosiphons and heat pipes, hermetically sealed pipes containing vaporizing agents and passively transport heat from a heat source to a heat sink (usually the environment). Of particular scientific and technological interest is the reliable removal of decay heat both from the spent fuel pool and from the reactor core, especially in accident scenarios like the loss of the ultimate heat sink or a station black out. An innovative and passive approach are thermosiphons, which can be used to cool the spent fuel pool in new and existing reactors or in dry storage facilities located away from the reactor in an external building. Heat pipes are also a key component for heat pipe cooled microreactor designs with a power level less than 10 MW el . Several designs are transportable or mobile, which makes them attractive for use in civilian as well military crises areas or even in space, e.g., on Moon or for powering space propulsion systems. In this publication an overview of all three technologies is provided (thermosiphons for cooling the spent fuel pool, heat pipes for microreactor core cooling as well as transportable and mobile, heat pipe cooled microreactors). It is divided into two parts. The first part discusses the regulations, thermosiphons and heat pipes, and the second part the microreactors.