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Figure 1 Change in pH, Gas Concentration, and Nitrogen Compounds With Excess Oxygen Added | Up
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CHEMISTRY PARAMETERS |
Reactor Water Chemistry
DOE-HDBK-1015/2-93
EFFECTS OF RADIATION
ON WATER CHEMISTRY (SYNTHESIS)
Rev. 0
CH-03
Page 11
Summary
The important information in this chapter is summarized below.
Effects of Radiation on Water Chemistry (Synthesis) Summary
The intense radiation inside the core of an operating nuclear reactor produces several
chemical effects on the reactor coolant itself and on substances dissolved in the
coolant. Radiation causes pure water to decompose into H and O . The
2
2
decomposition is suppressed by adding excess hydrogen.
2H O 2H + O
2
2
2
Excess hydrogen is added to suppress the decomposition of reactor water. It also
reacts with any oxygen that enters the reactor coolant system, usually as a component
of air in makeup water, provided the amount of oxygen is not excessive. If the
amount of oxygen is more than enough to deplete the hydrogen, the excess oxygen
reacts with nitrogen (also a component of air) and forms nitric acid. In the case of
addition of very large amounts of air, the amount of nitric acid produced may be
more than enough to neutralize the normally basic coolant and cause it to become
acidic.
Radiation induces the combination of N and H to form ammonia, although the
2
2
extent of this reaction is small and usually has a negligible effect on the pH of reactor
coolant. All of the reactions in this chapter are reversible and reach an equilibrium
state under normal operating conditions. Changes in the concentrations of any of the
reactants disturb the equilibrium and causes the reaction to shift in the direction
which restores the equilibrium.
N + 3H 2NH
2
2
3
Radiation also produces several nuclear reactions in reactor coolant. The products
N and N, of two of these reactions, contribute radioactivity to the reactor coolant,
16
17
7
7
adding significantly to the shielding requirements for nuclear reactors. Others, N
13
7
and F, are also major contributors to the radioactivity in reactor coolant.
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9
N O +
+
N O +
+ n +
16
16
17
16
1
7
8
7
8
0
N C +
F O +
13
13
0
18
18
0
7
6
+1
9
8
+1
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