Heatpipe Power SystemHPS reactors are the most promising technology for the
power system of the Epsilon Eridani mission. HPS reactors are a
nuclear-powered system that makes use of a small nuclear reactor
on-board the spacecraft. These power systems have greater power
generation compared to RTGs, greater spacecraft longevity, and greater
range and propulsion power than any other technology available today.
NASA has produced a small experimental HPS nuclear fission reactor for
electricity production on deep space missions called Safe Affordable
Fission Engine, SAFE-400. Safe-400 was developed at Los Alamos National
Laboratory and can produce 400 kWt of thermal power that can be turned
into 100 kWe of electric energy using the Brayton cycle gas turbine. The
device weighs about 1,200 kg and is about 50cm tall and 30cm across,
making it an ideal size for use in a spacecraft.
Source: http://highpowerrocketry.blogspot.com/2010_10_01_archive.html
The SAFE-400 is fueled
by 381 uranium nitride, UN, pins that are clad with rhenium. There are
127 identical molybdenum-sodium heatpipes that are surrounded by 3 UN
pins. The fission energy is conducted from the UN pins to the
molybdenum-sodium heatpipes that carry the heat to an ex-core heatpipe
and-to-gas heat exchanger. The safety of this device is a key issue for
use on a spacecraft. The SAFE-400 is designed for all launch or reentry
accidents. The safety of the device is accomplished by using rhenium as
the primary fuel cladding material so the reactor remains sub-critical
even if entirely submersed in water. SAFE-400 is cooled by heatpipes
and does not require any hermetically sealed vessel or any component
required by a pumped-loop system. The result of this simplicity is a
very reliable system that has a long lifetime. The actual lifetime of
the device depends on the life of the fission fuel used to power the
reactor. SAFE-400 presents the capabilities of an HPS nuclear fission
reactor aboard a spacecraft and, as long as the fuel is chosen so that
it will last approximately 80,000 years, this form of a power system
proves to be the best choice for the mission to Epsilon Eridani. |
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