FRA020056.3 VOLETS N4 GB - AREVA

Successful
implementation at Chooz
and Civaux (France)
The Chooz and Civaux
N4 units exceed initial
expectations.
The nominal power of Chooz B and Civaux
units, for base-load operation on the grid,
has been increased by 50 MWe, from 1,450 to
1,500 MWe.
In 2003, the Chooz and Civaux units were
in their fifth and fourth production cycles.
In January 2002, one N4 unit produced as
much as 1.13 TWh in one month (a world
record).
In 2002-2003, one N4 unit operated 700 days
without an automatic shutdown (scram).
The recorded annual radioactive releases
(both gases and liquids) are less than 1% of
the regulatory limits.
The average annual collective radiation
dose (operation and maintenance) per reactor
recorded for the N4 units is less than
0.5 man.Sievert (the average value observed
in OECD countries’ fleets of reactors are
close to 1 man.Sievert).
Ease of maintenance has been
demonstrated.
The N4 concept: a concrete
basis for developing new
NPP projects
N4 TECHNICAL CHARACTERISTICS
Net electrical output
1,450/1,500 MW
Gross thermal output
4,250 MW
Net efficiency 34/35%
Inner containment
prestressed concrete 1.2 m thick
Outer containment
reinforced concrete 0.55 m thick
Number of reactor loops 4
Operating pressure
155 bar abs.
RV* inlet temperature
292.2°C
RV* outlet temperature
329.6°C
Steam pressure at SG** outlet 72.3 bar abs.
Steam temperature at SG** outlet 288°C
Number of fuel assemblies 205
Average linear power density 179.6 W/cm
Number of control rod assemblies 73
*RV: reactor vessel
**SG: steam generator
Innovative and high performing steam generators
are one of the major advances of the N4.
Main features:
• axial mixed-flow economizer enhancing
the plant’s efficiency;
• heat transfer surface enlarged to 7,300 m 2
(6,900 m 2 for the previous 1,300 MW units);
• triangular pitch tube array instead of square
pitch for previous designs to increase tube
bundle compactness;
• tubes made of Inconel 690 to resist to stress
corrosion cracking;
• design improvements to facilitate inspection
and maintenance.
SECTION A
Pressure shell
Double wrapper
Bundle wrapper
Divider plate
90% recirculated water
10% recirculated water
100% feedwater
Pressure shell
A
Divider plate
Hot leg
Double wrapper
A
Bundle wrapper
Cold leg