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6 APPENDIX A - MARTIAN SURFACE NUCLEAR REACTOR
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 403 of 422
In the frame of the present study, the option of using a nuclear fission reactor to provide power
for the surface operations was considered in an early stage of the analysis. The design of the
reactor was primarily based on recent European space reactor studies.
Given the short surface stay of the proposed mission and the general conservative approach
chosen, the reactor option was considered not appropriate and is given here for completeness
sake and in the light of further studies involving longer surface stay times.
6.1 General parameters and initial assumptions
It is assumed that the nuclear fission reactor
• serves (only) to deliver electrical power;
• delivers 50 kWe (nominal);
• has a lifetime of about 10 years (minimum of 6 years at operational power);
• complies with international legal standards (especially 1992 UN COPUOS principles and
ICRP recommendations) in terms of operations, safety and radiation protection;
• is activated only after installation on the Martian surface (apart from zero-power testing
on Earth), (no operation during cruise);
• only one reactor is delivered – no system level redundancy.
As regards the total surface power of 50 kWe, note that the final power need of the surface stay
of the current mission scenario is only 3500 Wh/day, which corresponds to an average of 145W.
The power level of 50 kWe for the reactor assessment was made earlier and was maintained
essentially due to two reasons: there is a certain minimum power level for fission reactor systems
to become interesting in terms of specific power, furthermore, fission reactor power systems as
not scale linearly with the power levels provided and even strong decreases of the power need
might not change the total power system mass significantly.
6.2 Reactor type, mass and sizing aspects
6.2.1 General parameters
Compared to terrestrial and naval nuclear reactors, space reactors are orders of magnitude
smaller, in size as well as in power. While the basic principles remain identical – nuclear core
sustaining the controlled chain reaction, heat transport system, electricity generation from heat –
some subsystems are significantly different: waste heat rejection system (e.g. absence of
abundant water), natural coolant/moderator fluent circulation due to gravity, emergency systems
based on gravity.
6.2.2 Main differences to terrestrial systems