Environmental Engineering Reference
In-Depth Information
Enclosed electrical equipment
Battery packs.
2
Equipment of the technological systems:
Fixtures for transmitters
Impulse pipes and assemblies
Operation monitors
Relay boards
Cables for E, I&C equipment
Cables of containment electrical penetration for E, I&C
Cable joints and assemblies
Terminal boxes.
The basic issue at all VVER plants regarding electrical and I&C equip-
ment is the lack of or insuffi cient environmental qualifi cation. Lack of
initial qualifi cation of the VVER equipment was recognized in the 1980s
at all VVER-440/213 plants as well as at VVER-1000 “small series” and
VVER-1000/320 models.
Establishing the initial qualifi cation is understood as a current licensing
basis requirement at all VVER plants. This consists of the following steps:
D e fi nition of environmental parameters characteristic of the installation
site.
In the case of safety equipment, defi nition of environmental parameters
characteristic to the installation site under accidental (loss-of-coolant)
conditions.
Defi nition of accelerated thermal and radiation ageing test parameters.
Performing laboratory tests with the above parameters (accelerated
thermal and radiation ageing, radiation exposure with accident condi-
tion and simulation of loss-of-coolant conditions).
Performance checks on tested samples to verify conformity with accep-
tance criteria.
The maintenance of qualifi ed condition of the cables for harsh environmen-
tal conditions is a critical issue at VVER plants.
In regard to the cables, the technical task of qualifi cation is rather dif-
fi cult. For example at the Paks NPP there are 130 000 cables and among
them, several hundred types. The fi rst necessary measure related to the
cables was to develop a comprehensive database, instead of having the
cable sheets on paper. The database identifi es for each cable the safety clas-
ses, types and routes. The environmental conditions to which the particular
cables are exposed are identifi ed in the database. It also shows whether these
safety-related cables are affected by the harsher conditions after accidents.
Examples of ageing mechanisms of important cables are shown in Table 8.2.
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