ORNL-1771 - Oak Ridge National Laboratory

Four years of work on the ANP Project at ORtdL
have led to the belief that the circulating-fluoride-
fuel reactor with reflector moderation and a spheri-
cal-shell heat exchanger can be developed into
an aircraft power plant of exceptionally high per-
formance.' This view has been supported in
recent months by the results of studies by USAF
contractors. The question has now became how
best to bridge the gap between the ARE and a
prototype aircraft power plant.
It was proposed about a year ago that a 50-Mw
reactor be built so that the feasibility of con-
structing and operating a circulating-fuel reflector-
moderated reactor could be investigated and its
performance characteristics, particularly with ref-
erence to control, shielding, heat transfer, and fluid
flow, could be determined. Preliminary estimates
indicated that a power of at least 25 Mw would
be required to disclose the more important control
characteristics. Other studies indicated that an
output of 50 Mw would be required for the lowest
powered aircraft likely to be tactically useful (for
radar picket ships, patrol bombers, etc.), while
an output of 150 to 200 Mw would be required (with
chemical-fuel augmentation) to power a strategic
bomber. Preliminary reactor test unit designs and
cost estimates indicated that the time and cost
involved would be roughly proportional to the rated
output of the reactor (largely because the size
and cost of the heat exchangers, pumps, and heat-
dump equipment vary directly with reactor power).
After much analysis and discussion it was decided
that 60 Mw represented a good compromise for the
power rating and that such a reactor, to be called
the Circulating-Fuel Reactor Experiment (CFRE),
should be built by QRNL, with the aid of the
Pratt & Whitney Aircraft Division. This test unit
is to embody the basic features and proportions
that have made the circulating-fuel reactor ottractive
for aircraft use, but the details of the
pumps, radiators, and auxiliary equipment w~ll not
have to meet aircraft requirements of size, weight,
etc. An operating life of 500 hr, of which a sub-
stantial portion should be at or near 60 Mw, was
'A. P. Fraas and A. W. Savolainen, ORNL Azrcra/t
Nuclcnr Power Planf Deszgns, ORNL-1721 (in press].
2. REFLECTOR-MODERATED REACTOR
A. P. Fraas
Aircraft Reactor Engineering Division
PERIOD ENDING SEPTEMBER 70, 7954
considered to be a desirable goal. The information
gained from this project should serve to provide
a sound basis for the design of the full-scale
aircraft reactor.
As has been the case with the ARE, the CFRE
will require a major supporting effort on the part
of various groups in the QRNL organization to
obtain much essential information not yet avail-
able. The program on fuel chemistry, for example,
will continue along the lines it has followed. The
results of research on Loth the basic chemistry
and the in-pile and out-of-pile corrosion tests are
obviously vital to the project. Metallurgical re-
search on promising alloys, welding and brazing
techniques, strength properties at various tempera-
tures and in various ambients, and related work
will help greatly to increase the reliability, and
possibly the operating temperature, of the system.
Tests under way at the Tower Shielding facility
coupled with further Lid Tank Shielding Facility
tests will provide a more complete basis for the
aircraft shield design. Multigroup calculations
coupled with critical experiments should provide
additional information on the static physics of
the reactor. Much test work in experimental engi-
neering will be required to validate key features
of the design.
DESIGN OF THE CFRE
A. P. Fraas R. W. Bussard
Aircraft Reactor Engineering Division
The design of the CFRE is still preliminary,
but some tentative data can be presented at this
stage. As presently conceived, the CFRE will
i nc lude a react or, heat-exchanger, pres sure-she I I ,
and shield assembly, as described in previous
report^.^^^ A quasi-unit shield structurally and
functionally similar to one suitable for an aircraft
will probably be used,4 although the structure will
2A. P. Fraas, ANP Qunr. Prog. Rep. Mar. 10, 1953,
ORNL-1515, p 61.
3R. W. Bussard and A. P. Fraas, ANP Quur. Prog.
Rep. Dec. 10, 1953, ORNL-1649, p 31.
4E. P. Blizord and H. Goldstein (eds), Report u/ the
1953 Sunrmer Thzrldzng Sesrzon, ORNL-1575 (June 11,
1954).
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