The core of the nuclear reactor at the Tehran University is located in
a pool with capacity 500,000 liters at a depth of 8 meters. The pool is filled
with city water after passage through a demineralizer system which Increases
the specific resistance of city water from 2000 Ohms per cc to about 1000,000
Ohms per cc.
The reactor is used as a source of neutrons for radioisotope production,
etc. The reaction of neutrons with the constructional material of the reactor
such as aluminum produces ions which are all radioactive. 24Na , 27Mg , 28Al
are produced from 27AI by neutron absorption. Due to the existence of these
radioactive ions and the following reasons, a nuclear reactor such as the one
at the Tehran Univ. Nuclear Center, must have a demineralizer system to remove
the ions:
a--The impurities III the city water, such as Ca, K etc. become radioactive
in the reactor.
b - Pool water must be free of impurities III order to prevent the fuel
element corrosion.
c - The higher the specific resistance of the water, the less will be the
penetration of the core gamma rays to the pool surface area.
Details of the de mineralizer system J its recharging process and other
characteristics are given in the paper.