TNAG-1508-FCO40-2066-Guangdong-nuclear-power-station-project-at-Daya-Bay-safety-c-1987 — Page 79

line" analysis such as analysing the suplhur content of oil etc;

(2)

Gamma logging instruments:

seams. The logging instrument

These are used for finding coal

equipped with a cobalt-60 source

and a detector is placed into a borehole. The gamma rays emmitted

in all

radiation in different ways,

directions. Since

gamma

different levels of gamma radiation.

thickness of the coal seam can be accurately distuinguished

measured.

from the cobalt-60 penetrate the walls of the bore hole

coal seams and rock strata scatter and absorb

detector the

measures

As a result, the depth and

and

(3)

Neutron

logging

instruments:

exploitation of oil fields.

These are

used

in

the

The logger, equipped with a neutron

The neutron source gives

off

source, is placed in a borehole. fast neutrons in all directions. Hydrogen is very good at slowing down neutrons. Other elements are not so effective.

down neutrons are captured by other

The slowed

elements and

a

nuclear

reaction (n, gamma) occurs in which gamma radiation is given off. measuring the intensity of the gamma radiation it is possible to discover the hydrogen content of the rock strata and work

By

out

levels. Neutron logging

the position of

oil,

gas and water

provides

reliable

data

to aid the

rational

exploitation

and

consistently high production of oil fields.

1.

The use of excitation and ionization

The following isotopic instruments have been designed on the principle that matter is excited and ionized through irradiation. (1) Ionic smoke detector and automatic fire alarm: This uses the

effect of radiation from a radio-isotope on air

ionization

and

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