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Nuclear modules for space electric propulsionAnalysis of interplanetary cargo and piloted missions requires calculations of the performances and masses of subsystems to be integrated in a final design. In a preliminary and scoping stage the designer needs to evaluate options iteratively by using fast computer simulations. The Oak Ridge National Laboratory (ORNL) has been involved in the development of models and calculational procedures for the analysis (neutronic and thermal hydraulic) of power sources for nuclear electric propulsion. The nuclear modules will be integrated into the whole simulation of the nuclear electric propulsion system. The vehicles use either a Brayton direct-conversion cycle, using the heated helium from a NERVA-type reactor, or a potassium Rankine cycle, with the working fluid heated on the secondary side of a heat exchanger and lithium on the primary side coming from a fast reactor. Given a set of input conditions, the codes calculate composition. dimensions, volumes, and masses of the core, reflector, control system, pressure vessel, neutron and gamma shields, as well as the thermal hydraulic conditions of the coolant, clad and fuel. Input conditions are power, core life, pressure and temperature of the coolant at the inlet of the core, either the temperature of the coolant at the outlet of the core or the coolant mass flow and the fluences and integrated doses at the cargo area. Using state-of-the-art neutron cross sections and transport codes, a database was created for the neutronic performance of both reactor designs. The free parameters of the models are the moderator/fuel mass ratio for the NERVA reactor and the enrichment and the pitch of the lattice for the fast reactor. Reactivity and energy balance equations are simultaneously solved to find the reactor design. Thermalhydraulic conditions are calculated by solving the one-dimensional versions of the equations of conservation of mass, energy, and momentum with compressible flow.
Document ID
19980209999
Acquisition Source
Headquarters
Document Type
Conference Paper
Authors
Difilippo, F. C.
(Oak Ridge National Lab. TN United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1998
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
CONF-980103-1
DE97-009366
Meeting Information
Meeting: Space Technology and Applications International Forum
Location: Albuquerque, NM
Country: United States
Start Date: January 25, 1998
End Date: January 29, 1998
Funding Number(s)
CONTRACT_GRANT: DE-AC05-96OR-22464
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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