Areva EPR

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■ EPR NUCLEAR ISLAND REACTOR CORE † The reactor core contains the fuel material in which the fission reaction takes place, releasing energy. The reactor internal structures serve to physically support this fissile material, control the fission reaction and channel the coolant. The core is cooled and moderated by light water at a pressure of 155 bar and a temperature in the range of 300 °C. The coolant contains soluble Boron as a neutron absorber. The Boron concentration in the coolant is varied as required to control relatively slow reactivity changes, including the effects of fuel burnup. Additional neutron absorbers (Gadolinium), in the form of burnable absorber-bearing fuel rods, are used to adjust the initial reactivity and power distribution. Instrumentation is located inside and outside the core to monitor its nuclear and thermal-hydraulic performance and to provide input for control functions. The EPR core consists of 241 fuel assemblies. For the first core, assemblies are split into four groups with different enrichments (two groups with the highest enrichment, one of them with Gadolinium). For reload cores, the number and characteristics of the fresh assemblies depend on the type of fuel management scheme selected, notably cycle length and type of loading patterns. Fuel cycle lengths up to 24 months, IN-OUT and OUT-IN fuel management are possible. The EPR is designed for flexible operation with UO 2 fuel and/or MOX fuel. The main features of the core and its operating conditions have been selected to obtain not only high thermal efficiency of the plant and low fuel cycle costs, but also extended flexibility for different fuel cycle lengths and a high level of maneuverability. Core instrumentation The core power is measured using the ex-core instrumentation, also utilized to monitor the process to criticality. The reference instrumentation to monitor the power distribution in the core is an “aeroball” system. Vanadium balls are periodically inserted in the core. Their activation level is measured, giving values of the local neutron flux to construct the three-dimensional power map of the core. The fixed in-core instrumentation consists of neutron detectors and thermocouples to measure the neutron flux distribution in the core and temperature distribution at the core outlet. The whole in-core instrumentation package is introduced from the top of the reactor pressure vessel head. Therefore, the bottom of the reactor pressure vessel is free from any penetration. For additional information see the “Instrumentation and Control systems” chapter, page 42. The core design analyses demonstrate the feasibility of different types of fuel management schemes to meet the requirements expressed by the utility companies in terms of cycle length and fuel cycle economy (reload fraction, burnup), and to provide the core characteristics needed for sizing of the reactor systems. The nuclear analyses establish physical locations for control rods, burnable poison rods, and physical parameters such as fuel enrichments and Boron concentration in the coolant. The thermal-hydraulic analyses establish coolant flow parameters to ensure that adequate heat is transferred from the fuel to the reactor coolant. Isar 2 unit, Germany (KONVOI, 1,300 MWe): fuel loading operation. 16 I
In-core instrumentation 12 lance yokes, each comprising: – 3 T.C core outlet – 6 in-core detectors – 3 or 4 aeroball probes 1 T.C upper plenum 89 control assemblies 4 water level CHARACTERISTICS DATA Reactor core Thermal power 4,500 MWth Operating pressure 155 bar Nominal inlet temperature 295.6 °C Nominal outlet temperature 328.2 °C Equivalent diameter 3,767 mm Active fuel length 4,200 mm Number of fuel assemblies 241 Number of fuel rods 63,865 Average linear heat rate 156.1 W/cm Typical initial core loading T.C G G G G G G G G Ex-core Aeroball In-core G G G G G G G G G G G G G G G G G G G G T.C: Thermocouple G High enrichment with Gadolinium High enrichment without Gadolinium Medium enrichment Low enrichment † The EPR core is characterized by considerable margins for fuel management optimization. † Several types of fuel management (fuel cycle length, IN-OUT/OUT-IN) are available to meet utilities’ requirements. † The main features of the core and its operating conditions give competitive fuel management cycle costs. † The EPR core also offers significant advantages in favor of sustainable development: • 17% saving on Uranium consumption per produced MWh, • 15% reduction on long-lived actinides generation per MWh, • great flexibility for using MOX (mixed UO 2 -PuO 2 ) fuel assemblies in the core, i.e. of recycling the plutonium extracted from spent fuel assemblies. I 17
Page 1 and 2: EPR
Page 3 and 4: • EDF (Electricité de France), a
Page 5 and 6: FOREWORD Security of energy supply
Page 7 and 8: TABLE OF CONTENTS page 08 page 44 p
Page 9 and 10: EPR LAYOUT page 10 >PRIMARY SYSTEM
Page 11 and 12: Water outfall Switchyard Water inta
Page 13 and 14: 2 t +8.50m 1 2 3 4 5 6 1 2 8 6 1 5
Page 15: CHARACTERISTICS DATA Reactor coolan
Page 19 and 20: 17 x 17 fuel assembly CHARACTERISTI
Page 21 and 22: Plug connector Upper limit position
Page 23 and 24: Reactor pressure vessel and interna
Page 25 and 26: Heavy reflector The heavy reflector
Page 27 and 28: Steam generator cutaway Secondary m
Page 29 and 30: Reactor coolant pump cutaway 1 2 3
Page 31 and 32: CHARACTERISTICS DATA Main coolant l
Page 33 and 34: CHARACTERISTICS DATA Pressurizer De
Page 35 and 36: SAFETY INJECTION / RESIDUAL HEAT RE
Page 37 and 38: OTHER SAFETY SYSTEMS The Extra Bora
Page 39 and 40: FUEL HANDLING AND STORAGE The react
Page 41 and 42: Computer-generated image of the EPR
Page 43 and 44: Limitation functions and protection
Page 45 and 46: NUCLEAR SAFETY The fission of atomi
Page 47 and 48: EPR SAFETY The first important choi
Page 49 and 50: Optimized management of accidental
Page 51 and 52: The dedicated corium spreading and
Page 53 and 54: EPR CONSTRUCTION TIME SCHEDULE The
Page 55 and 56: PLANT OPERATION, MAINTENANCE & SERV
Page 57 and 58: Operators have developed ambitious
Page 59 and 60: EPR Key to power station cutaway 1

Areva EPR

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