The operation of the White Sands Missile Range Fast Burst Reactor is discussed. Space radiation studies in radiobiology, dosimetry, and transient radiation effects on electronic systems and components are described. Proposed modifications to increase the capability of the facility are discussed

Delapaz, A.

English

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SPACERADIATIONSTUDIESATTHE WHITE SANDS MISSILE RANGE FAST BURST REACTOR
A. De La Paz
(Nuclear Weapon Effects Division, Army Missile Test and Evaluation,
White Sands Missile Range, New Mexico)
The White Sands Missile Range Fast Burst
Reactor (FBR) has been employed in the perform-
ance of various types of space radiation tests.
The FBR is operated by the Department of the
Army to provide the radiation environment in
support of requirements of experimenters from
private industry, government agencies and
their contractors. The FBR is an unreflected
and unmoderated reactor employing an alloy or
uranium-lO weight percent molybdenum as the
fuel material. The reactor core, consisting
of a stacked array of fuel rings, and the
control components, including a safety block,
control rods and burst rod, are all made of
the same fuel material.
The FBR is operated at either an outdoor site
or inside an underground reactor cell having
approximately a 50 x 50 ft floor area and a
height of 20 ft. Because of the size of the
reactor cell, most of the experiments are
conducted with the reactor in the cell. Out-
door reactor operations are conducted where large
items, such as vehicles, are to be irradiated,
or when the distance from the experiment to the
reactor is to be large. In the usual case, where
the reactor is in the cell, the experiment
being studied is placed on an experimenter table
through which the reactor core protrudes. A
safety shield surrounds the reactor core assembly
and serves to prevent movement of the experiment
to a point where it could touch the reactor fuel
surface. The FBR can be operated in either a
burst or steady-state mode, depending on the
experimenter requirements that apply.
The experiment being studied is instrumented and
the necessary cabling _s run from the reactor
cell to the experimenter room at the reactor
facility where the response of the experiment
to radiation is observed, recorded and evaluated.
Included with the instrumentation of the
experiment is the dosimetry measurement techniques
that are provided. Normally, the neutron fluence
is measured by use of sulfur foils and the gamma
measurements are made with calcium fluoride
or lithium fluoride thermoluminescent dosimeters.
Dosimetry support for experimenters using the
reactor facility is provided by the Nuclear
Weapon Effects Division. This support includes
the foils and dosimeters and the counting and
analysis necessary to obtain the required
dosimetry data. The neutron and gamma output
characteristics of the reactor are presented in
Figures i and 2.
Space radiation studies conducted at the FRB
include radiobi01oglcal experiments, dosimetry
studies and transient radiation effects studies
on electronic systems and components. Radio-
biological experiments conducted using the FBR
have involved the evaluation of the behaviorial
response of animals subjected to the radlatio_
environment associated with a reactor burst
operation. In one category of experiments rhesus
monkeys, trained to perform tasks such as
maintaining a moving platform on a stable basis,
are subjected to a radiation burst which gives
them a dose of approximately 2500 Reds to the
head. The response and performance of the animal
is followed for an extended period of time.
Studies of this type are being carried out at
lower doses to the animal. In addition, studies
have been carried out using baboons instead of
rhesus monkeys. For the most part, however,
radiobiological experiments are conducted with
the rhesus monkeys because of the more extensive
performance degradation data that can be obtained
as compared to the baboons. An additional
complicating factor involved with the baboons is
that more elaborate measures must be taken to
insure that the animal is restrained so that it
cannot move in a manner such that it would alter
the reactivity state of the reactor. Radio-
biological experiments have also been conducted
at the reactor facility with other animals; for
example, dogs and laboratory rats.
Performance of space radiation studies on
electronic systems and components is a major use
of the reactor facility. Individual components,
such as transistors or diodes, are placed in very
close proximity to the reactor, approximately
six inches from the core eenterline, and receive
the programmed radiation deposition depending
on the fission yield associated with the reactor
burst operation. Performance of experiments of
this type is expanded to include entire electronic
systems, such as missile guidance packages.
Modification of the FRB facility is planned for
1971 which will include provision for an internal
irradiation cavity within the reactor core for
high intensity radiation deposition of small
components. In addition, the operational
capability of the reactor is being upgraded to
provide progressively higher radiation doses to
experiments in either the burst or steady-state
mode of operation.
618
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619


Space radiation studies at the White Sands Missile Range Fast Burst Reactor

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