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Modeling transient thermalhydraulic behavior of a thermionic fuel element for nuclear space reactors

A transient code (TFETC) for calculating the temperature
distribution throughout the radial and axial positions of a
thermionic fuel element (TFE) has been successfully developed.
It accommodates the variations of temperatures, thermal power,
electrical power, voltage, and current density throughout the
TFE as a function of time as well as the variations of heat
fluxes arising from radiation, conduction, electron cooling,
and collector heating. The thermionic fuel element transient
code (TFETC) is designed to calculate all the above variables
for three different cases namely: 1) Start-up; 2) Loss of flow
accident; and 3) Shut down.
The results show that this design is suitable for space
applications and does not show any deficiency in the
performance. It enhances the safety factor in the case of a
loss of flow accident (LOFA). In LOFA, it has been found that
if the mass flow rate decreases exponentially by a -0.033t,
where t is a reactor transient time in seconds, the fuel
temperature does not exceed the melting point right after the
complete pump failures but rather allows some time, about 34
seconds, before taking an action. If the reactor is not shut
down within 34 seconds, the fuel temperature may keep
increasing until the melting point of the fuel is attained. On
the other hand, the coolant temperature attains its boiling
point, 1057 ��K, in the case of a complete pump failure and may
exceed it unless a proper action to trip the reactor is taken.
For 1/2, 1/3, and 1/4 pump failures, the coolant temperatures
are below the boiling point of the coolant. / Graduation date: 1994

Identiferoai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/35507
Date20 September 1993
CreatorsAl-Kheliewi, Abdullah S.
ContributorsKlein, Andrew C.
Source SetsOregon State University
Languageen_US
Detected LanguageEnglish
TypeThesis/Dissertation

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