Environmental Engineering Reference
In-Depth Information
8.2.1 Basic design features of the VVER-440
The V-179, V-230 and V-213 types of VVER plants are equipped with a
six-loop VVER-440 reactor. In each loop, there are main isolating valves
(MIV) on the cold and hot legs, one main circulation pump (MCP) per loop
and horizontal steam generators (SG). The pressurizer, with safety valves, is
connected to the primary loop. The two generations of the VVER-440 type
of reactors have very similar layouts in their primary systems. Typical oper-
ating parameters are
T
hot
=297 ° C,
T
cold
=266 ° C,
p
=12.3 MPa. However, the
design bases of the VVER-440/230 and the VVER-440/213 are essentially
different, which manifests in the design of safety systems and confi nement
(IAEA, 1992; 1996a).
There are 16 nuclear power plant units of type VVER-440/213, namely,
four in Hungary, four in the Czech Republic, four in Slovakia, two in Russia
and two in Ukraine. The owners of these plants are preparing for the LTO
of these units.
The design bases for the VVER-440/213 safety systems are similar to
those used in Western PWRs, including the postulating of a double-end
guillotine break of the main circulation line in the reactor coolant sys-
tem. The safety systems exhibit triple redundancy and the reactors have
bubbler condenser-type, pressure suppression containments capable
of withstanding the imposed loads and maintaining containment func-
tionality, even following large break LOCA events. The design of the
VVER-440/213 plants considered internal and external hazards to some
extent. Protection against single failures in the auxiliary and safety sys-
tems has generally been provided in the design. The safety concerns with
VVER-440/213 plants are discussed in the IAEA report (1996a). The
VVER-440/213 has essentially inherent safety characteristics, for example
robustness of the design, low heat fl ux in the core, large water inventory
in the primary system and a large containment volume, which compen-
sates to a large extent for other defi ciencies in the containment concept.
At all of the plants, most of the safety defi ciencies have been addressed by
retro-fi tting and plant modifi cations. Due to the robustness of the design,
it was feasible to upgrade the safety of the original VVER-440/213 design
to a level comparable with the PWR plants of the same age. The latest
constructed units of VVER-440/213, such as Mochovce NPP Units 1 and 2,
had several improvements and modifi cations made during the design and
construction phase.
There are specifi c modifi cations of the VVER-440 design: the
Finnish nuclear power plant at Loviisa, represents a combination of
the VVER-440/230 basic design and nuclear island equipment with a
Westinghouse-type, reduced pressure, ice-condenser containment and sev-
eral other western-designed and manufactured systems, like the complete
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