Environmental Engineering Reference
In-Depth Information
Temperature: in the case of organic materials, commonly used as insu-
lation and/or sealing parts of components, high temperature is the main
factor of ageing
Radiation: inside the containment,
-rays are mainly taken into account.
The most sensitive material is PVC and the least sensitive is XLPE.
Therefore, PVC insulated cables are not used for safety-related func-
tions inside the containment. Neutron radiation is be considered only
for copper parts located next to the reactor, where these parts may be
activated
Pressure changes: extreme pressure changes may occur in loss-of-cool-
γ
ant conditions and may endanger the proper operation of systems and
components by affecting the sealing materials of some equipment
Humidity: humidity in the containment may change for several reasons,
for example leakage or pipe breakage, unintended operation of fi re
extinguishing appliances. Penetrating humidity may result in malfunc-
tion of electrical and I&C equipment.
Steam: under LOCA conditions, steam may condense on the surface of
equipment causing rapid temperature rise and it may also penetrate into
the equipment.
Chemicals: the applied chemicals (boric acid, hydrazine, etc.) may pene-
trate into seals of electrical equipment, reducing dielectric strength, and
causing corrosion.
Seismic events: seismic effects and vibration may degrade the func-
tionality of certain electrical and I&C equipment (relays, transmitters,
motors, etc.)
Identifi cation of the ageing mechanisms for civil structures and structural
components is discussed by Katona
et al
. (2009a). Examples are given in
Table 8.5 on the basis of Hungarian regulatory guide No. 1.26.
Structuring of ageing management programmes
The VVER plants developed different types and systems of ageing manage-
ment programmes:
Overall plant AMP
AMPs addressing a degradation mechanism
Structure- or component-oriented AMP.
Overall plant AMP
An AMP for an overall plant can be developed and implemented for: defi -
nition of goals of the operating company, distribution of responsibilities in
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