Concentration of Evaporator Concentrates - NUKEM Technologies

CONCENTRATION OF
EVAPORATOR CONCENTRATES
Introduction
The main liquid radioactive waste
stream generated during the
operation of nuclear power plants
consists of evaporator concentrates
produced in the central evaporator of
the plant. The quantity of that kind of
waste can be in the range of 30
m 3 /year to 300 m 3 /year, depending on
the reactor type and on the waste
water treatment technology.
The composition is variable as shown
in table 1.
Table 1: Composition of evaporator concentrates
Characteristics Range Typical
Total salts concentration (g/dm 3 ) 200 to 500 300
Total salts content (% by weight) 20 to 38 25
BO 3- 3 concentration (g/dm 3 ) * 80 to 180 120
Density (g/dm 3 ) 1150 to 1340 1200
Total activity concentration (Bq/dm 3 ) 3 ·10 6 to 2 ·10 8 5.5 ·10 7
* Not relevant in the case of boiling water reactor.
Depending on the storage
requirements of the chemical
composition and the activity
concentration of the final product, and
based on some economical
considerations, the treatment method
of the evaporator concentrates can
follow different processes, for
example:
• concentration to obtain a superconcentrate
which can be
cemented or bituminized
• concentration to obtain a product
suitable for vitrification
• concentration to obtain a salt block
which can be stored in approved
containers (the formation of salt
blocks is only possible if the
content of salts with crystal-water,
e.g. borates, is higher than 20% by
weight)
• concentration to obtain a dry
granular product that can be stored
in acceptable container
NUKEM Technologies GmbH
2007
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