A NUCLEONICS Survey— 
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Gamma-lrradiation Facilities 
in the United States 
By R. HOBART ELLIS, Jr., Associate Editor, NUCLEONICS 
About 40 high-level isotopic irradia- 
tion facilities are currently in use by 
schools and industrial and research 
establishments of the United States. 
They include a total of ~ 350,000 
curies of Co® and nine spent-fuel 
installations. These are among the 
results of a NUCLEONICS survey of such 
facilities. Some of the results are 
tabulated on the facing page. 
The survey supplements an earlier 
bibliography of similar information 
(NU, Nov. ’57, p. 170). No attempt 
has been made to include medical 
installations, particle-irradiation facili- 
ties or other sources of high-energy 
photons such as accelerators and X-ray 
generators. 
Many for public use. Of the facili- 
ties listed 20 indicate that they are 
available for public use, and 27 say 
that they are not. In some cases the 
answers were qualified to indicate that 
while the facility is generally used 
only by the owner company, there is 
no real objection to inquiries for 
service irradiation. 
Only eight facilities indicate that 
clearance is required for their use. 
Twenty-nine can accommodate classi- 
fied experiments. 
Largest source of the group is the 
Osk Ridge storage facility (NU, 
134 
March ’57, p. 98), currently rated at 
200,000 curies of Co®. This facility 
is no longer available for public use. 
Rapid Development 
The irradiator field is in a state of 
rapid change and development. So 
many companies have established their 
own facilities and so many of these 
offer service irradiations to outsiders 
that the Atomic Energy Commission 
has bowed out of the business. As of 
last March 31 it no longer offers gamma 
irradiations where industrial facilities 
are adequate for the purpose. Co® 
prices have been reduced and placed 
on a new schedule that gives advantage 
to large-quantity orders. The current 
range is $2-5 per curie, replacing a 
former range of $2-10 per curie (NU, 
Sept. ’57, p. 32). The price of Cs}37, 
often suggested as a substitute for 
Co® and widely used in Britain, has 
been reduced by a much larger factor— 
from $14 to $1-2 per curie (NU, May 
’58, p. 27). This isotope will soon be 
available in increased quantities from 
Oak Ridge. 
At least one irradiator is planned to 
use more Co® than all current sources 
combined. This High Intensity Food 
Irradiator (HIFI) will be installed at 
the Quartermaster Corps’s Sharpe 
General Depot at Lathrop, Calif. 
It is likely to contain ~2-million 
curies. The current annual Co® pro- 
duction rate in the United States of 
300,000 c/yr will have to be increased 
several fold if it is to supply irradiators 
of this magnitude. Additionally an 
AEC-sponsored study will evaluate 
the potential demand for large irradia- 
tors, and this may inspire further 
construction (NU, April ’58, p. 24). 
Lack of Standardization 
A serious difficulty in surveying the 
field is a need for vocabulary. It is 
probably impossible to find commonly 
recognized units for size, prices and 
irradiation capacity. 
Consider, for example, the matter of 
size. The curie of Co® is adequate 
for cobalt sources, but it does not 
permit comparison with photon radia- 
tion from other sources. The situa- 
tion becomes further complicated if one 
tries to include particle accelerators. 
The survey questionnaire asked for the 
radiation power in watts, but few of 
the people answering had this figure 
available. 
Prices for service irradiations are 
another potential source of confusion. 
They have probably not become 
important to irradiation people yet, 
but they will be more important when 
radiation becomes a commercial com- 
modity. Few people sent prices in 
terms of the units offered: $/hr, $/hr 
/ft? and $/megarad-lb. 
Irradiation capacity would be an 
interesting figure of merit, but no 
generally acceptable figure appears to 
be available to describe it. Few 
facilities were prepared to estimate 
their outputs in megarad-lb/hr. 
A set of suggested standards. It 
appears possible and desirable to 
define a set of quantities that would 
make irradiation facilities comparable. 
Preferably the set would include all 
types of irradiators—accelerators as 
well as isotopic sources. A usable set 
would appear to be the following: total 
radiation power (watts), potentially 
useful radiation (total radiation power 
less the amount inevitably lost by 
absorption in source and shielding), 
radiation efficiency (per cent of the 
useful radiation delivered to the sample 
in a particular geometry), radiation 
cost (dollars per megarad-lb). Other 
useful units could be derived; for 
example, the irradiation rate or produc- 
tion capacity in megarad-lb/hr. The 
irradiation field is growing at a rate 
that indicates the need for some 
standardization of this kind. 
