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5.4. SHIELD MOCKUP CORE
C. E. Clifford L. B. Holland
PERIOD ENDING JUNE 70, 7956
Tests of optimized reactor shield desSgns are the inlet cooling line. The CFRMR has a control
made, currently, with a full-scale mockup of the rod of slightly smaller diameter in this position,
shield and a known source. The effectiveness of but calculations have shown that the effect of the
the shield in its final application is then predicted cooling line will not be significant. The SMC will
by making source corrections. To date the source be controlled by using thin, curved plates confor
the shielding tests has often been a swimming- taining Blo at the outer edge of the island between
pool type of reactor, but with the circulating-fuel the fuel plates and the beryllium. In the core region
reflector-moderated reactor (CFRMR) now being it is proposed to use fixed fuel plates of UO, and
considered for aircraft propulsion it is considerably stainless steel, which will be similar in cross
more difficult to correct for the differences between section to the Army Package Power Reactor fuel
the two sources. In recent months it has become plates. The shape of the plates will be peculiar
apparent that a shield test with a reactor that more to the SMC. The feasibility of the shape has
nearly mocks up a CFRMR is required.
The construction of a 5Mw reactor that will use
already been determined with test fuel plates.
There will be a total of 200 vertical fuel plates
fixed fuel elements which will correctly mockup'all placed radially around the beryllium island, and
the radiation expected from the CFRMR designed normal water will be used as the coolant. The
by Pratt & Whitney, except the decay gamma rays core region will be separated from the beryllium
and rleutrons from the circulating fuel in the heat island and the reflector by lnconel shells, as reexchanger,
has been proposed. A preliminary de- quired by the CFRMR.
sign and a cost estimate are being prepared on The region above the CFRMR reactor core will
which to base a formal construction proposal. The be difficult to mock up. Since it constitutes a
reactorwill be called the Shield Mockup Core (SMC) small total angle,, it seems best, in the SMC, to
and will be used with the latest optimized shield attempt to black out radiation from this region.
at the Tower Shielding Facility (TSF) to determine Another feature in favor of this idea is that the
whether the calculated dose in the crew comport- control-rod drives and controlshamber leads will
ment agrees with the measured dose. It will also be in this region.
be used at the Bulk Shielding Facility (BSF), The reactor is being designed so hat it can be
where measwernents will be made of the spectra transported between the TSF artd the BSF with a
of neutrons and gamma rays emerging from the minimum amount of dismantling. The fuel can be
reactor shield. removed without disturbing the control rods of the
Calculations for the SMC have thus far been control chambers. This will be accomplished by
directed toward obtaining a go nts in a rotating rig that can be
the design effort has been dit
a simple yet flexible over-all de
on. A removable plug in the rig
as it is now planned, is described
differences between it and the
HE REFLECTOR
signs are noted. The SMC s lector of the SMC will be similar
CFRMR to show how c
the CFRMR, except at the top
ere the question of hydraulics
e CFRMR design. The sodium
May 1' 1957.
lector will be simulated
Ilium. If cooling is re-
Gometry of the CFRMR in the SMC (see Fig. 5.4.1). The first region outside the beryllium reflector
The central beryllium island will be cylindrical, will be the first boron curtain. In the CFRMR this
and its center will be removed to provide space for region consists of a layer of sodium, followed by
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