Areva EPR

Heavy reflector
The heavy reflector is an innovative feature with significant
benefits:
† By reducing the flux of neutrons escaping from the core,
the nuclear fuel is better utilized (more neutrons are
available to take part in the chain reaction process),
thereby making it possible to decrease the fuel cycle
cost by reducing the fuel enrichment necessary to reach
a given burnup, or to increase burnup with a given
enrichment.
† By reducing the neutron leakages from the core, the
Reactor Pressure Vessel is protected against fast
neutron fluence-induced aging and embrittlement,
helping to ensure the 60-year design life of the EPR.
† The reactor also provides advances in terms of
mechanical behavior of the internal structure
surrounding the core:
• a smooth stress distribution inside the structure, due to
an efficient inside cooling of the reflector, limiting loads
and avoiding deformation,
• no discontinuities, like welds or bolts, in the most
irradiated areas,
• a large decrease of depressurization loads to take into
account in case of assumed loss of coolant accident,
because there is no significant quantity of water
trapped in the structure around the core.
CHARACTERISTICS
DATA
Reactor pressure vessel
Design pressure
176 bar
Design temperature 351 °C
Life time (load factor 0.9)
60 yrs
Inside diameter (under cladding)
4,885 mm
Wall thickness (under cladding)
250 mm
Bottom wall thickness
145 mm
Height with closure head
12,708 mm
Base material 16 MND 5
Cladding material Stainless steel (Cobalt 0.06%)
Mass with closure head
526 t
End of life fluence level (E 1 MeV) IN-OUT
fuel management scheme with UO 2 1 x 10 19 n/cm 2
Base material final RT NDT
(final ductile-brittle transition temperature) 30 °C
Closure head
Wall thickness
230 mm
Number of penetrations for:
• Control rod mechanisms 89
• Dome temperature measurement 1
• Instrumentation 16
• Coolant level measurement 4
Base material 16 MND 5
Cladding material Stainless steel (Cobalt 0.06%)
Upper internals
Upper support plate thickness
350 mm
Upper core plate thickness
60 mm
Main material Z3 CN 18–10/Z2 CN 19–10
Lower internals
Lower support plate thickness
415 mm
Lower internals parts material Z3 CN 18–10/Z2 CN 19–10
Neutron heavy reflector
Material Z2 CN 19–10
Mass
90 t
† The design of the EPR reactor pressure
vessel internals is based on the N4 and
KONVOI proven designs.
† The heavy neutron reflector brings
an enhanced fuel utilization and protects
the reactor pressure vessel against aging
and embrittlement.
† A low Cobalt residual content of the
stainless steels is specified and the use
of Stellite hard-facing is optimized so
as to reduce radiation source term.
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