nations (7) of moderator, reflector and 
fuel element; it is not possible to list 
here more than a small fraction of these 
possibilities. 
In the open-pool reactor fuel can be 
added easily in increments of a single 
element to compensate for burn-up or 
experimental equipment and the shim 
rods need not control more than 7 or 
8% in reactivity. In the tank type on 
the other hand, because the cover must 
be removed and replaced, changing ele- 
ments is a time-consuming process and 
sufficient fuel is loaded at one time to 
allow for full burnup as well as the 
other effects. The shim rods must 
now be capable of controlling 15-20% 
in reactivity. 
Experimental Programs 
The number of experiments that can 
be performed with the aid of a research 
reactor is much too great to list in an 
article of this type. Detailed descrip- 
tions of a large number of physics ex- 
periments have been given by Hughes 
(8) and various materials investigations 
have been discussed by several other 
authors (9). 
It is possible, however, to make a 
general division into a group that can 
be carried out satisfactorily with fluxes 
less than 1013 n/em2/sec and those that 
require higher intensities. In the first 
group are found the so-called physics 
experiments. Of particular interest to 
the reactor designer are investigations 
of Fermi age in various materials, res- 
onance-integral measurements, cross- 
section determinations, and flux distri- 
butions in exponential assemblies. 
On the other hand, engineering in- 
vestigations of radiation damage, cor- 
rosion in the presence of radiation, fuel- 
element burnup, and circulating-fuel 
loops are performed more satisfactorily 
with fluxes in the neighborhood of 10'4 
n/em?/sec. Significant results often 
necessitate total doses (nvt) in excess 
of 102°n/em?. Such a dose requires an 
exposure time of nearly two weeks in 
a flux of 1014 n/cm?/sec. 
The equipment to take full advantage 
of neutron fluxes of the order of magni- 
tude of 10!4n/cm?/sec is generally com- 
plicated and expensive. The samples 
may need special cooling during irradi- 
ation and their activity is such that re- 
moval from the reactor and subsequent 
handling calls for extensive shielding 
and rather special remote-handling 
equipment. 
Beside work of immediate signifi- 
72 
cance to the development of power re- 
actors, the research reactor can be used 
for a host of experiments in physics, 
chemistry, and biology. Programs 
covering fields such as neutron diffrac- 
tion, activation analysis, production of 
radioactive isotopes, biological irradi- 
ations, food sterilization, catalytic ac- 
tions, and many others can all be car- 
ried out very satisfactorily in fluxes less 
than 10'3 n/cm2/sec or with the gam- 
mas from spent fuel elements. An 
alert and imaginative staff can keep a 
1-Mw research reactor busy on such 
programs for many years. 
Operating Personnel 
The personnel associated with a re- 
search reactor can be divided into two 
groups, (a) those directly concerned 
with the operation of the reactor, and, 
(b) those responsible for carrying out 
the various experiments and tests. 
Normally, the second group is by far 
the larger and since its size and com- 
position depend on the experimental 
program no detailed description of this 
group will be attempted here. 
A minimum organization for oper- 
ating a 0—5-Mw research reactor is as 
follows: 
Supervisor (one)—In charge of the 
reactor and facility operation. He 
schedules the work, oversees operation, 
decides whether adequate safety pre- 
cautions have been taken when a new 
experiment is introduced into the facil- 
ity, sets maintenance schedules, and in 
general is responsible for safe operation 
of the facility. 
Health physicist (one per shift)—Re- 
sponsible for safety of personnel. He 
maintains exposure records by means 
of film badges and dosimeters, exam- 
ines experimental equipment to insure 
that personnel will not be overexposed, 
oversees cleanup after any spill, and is 
available for consultation on shielding 
and similar matters. 
Reactor operator (one per shift)—In 
charge of actual operation of reactor. 
He is responsible for routine startups, 
maintenance of proper power level, 
routine instrument testing to insure 
that the control and safety circuits are 
functioning properly, and immediate 
supervision aimed at preventing any 
dangerous situations from arising. 
Instrument mechanic (one)—Respon- 
sible for testing and repair of safety 
and control circuits and other reactor 
mechanisms. 
Auxiliary personnel. Onesecretary, 
janitors, guards, or night watchmen, 
etc. as ordinarily found in a research 
installation of this size. 
This organization should be ex- 
panded if members of the experimental 
group lack experience in working with 
radioactive material. For example, it 
may be desirable for the operating 
group to offer irradiation service and 
one technician can be employed full 
time for this work. 
Visitors pose a problem. In most 
cases they should not be allowed to 
wander unaccompanied through the 
facility. If the reactor is the first of 
its kind near a populous area the num- 
ber of visitors may justify the appoint- 
ment of an assistant director to cope 
with them. 
Operating Costs 
Operating costs of the reactor and 
cooling system are small compared 
with the cost of the experimental pro- 
gram. Again no figures are given for 
the latter since its magnitude is deter- 
mined by the scope of the experimental 
work. The principal operating costs 
for a 5-Mw research reactor are as 
follows: 
Fuel burnup. At $25/gm of U?** the 
burnup cost will be $31.25/Mw-day. 
(Approximately 1.25 gm of U?** are 
fissioned or are converted to U2%* per 
Mw-day of energy released.) 
Fuel rent. At 4% per annum the 
cost of holding 5 kg of U?** is $5,000 
per year. 
Electric power. A 5-Mw reactor, 
controls and cooling system will re- 
quire about 250 kw of electric power. 
(The building services are in addition 
to this.) Thus the electric power cost 
will be of the order of $85/day for 24- 
hr/day operation. 
Process water. Pool makeup re- 
quires 2 gpm; 2-40 gpm makeup is 
required for the cooling tower, depend- 
ing on wet bulb temperature. 
Supplies and equipment. Those 
peculiar to reactor operation include 
film badges, certain electronic items, 
chemicals for regenerating demineral- 
izer, etc. Experience indieates an an- 
nual cost between $5,000 and $10,000 
for these. Ordinary supplies and serv- 
ices, those normal to operation of any 
research establishment of this size such 
as telephones, pick-up truck, janitor’s 
materials, etc., cost another $5,000— 
$10,000 annually. 
How costs scale. As the size of the 
reactor increases the operating costs go 
