Areva - Reference Document 2016

06

BUSINESS OVERVIEW

The world’s most prevalent reactor: the pressurized water reactor In light water reactors, the fuel is low-enriched uranium. The water in the primary cooling systembathes the reactor core, consisting of tubes containing the fuel, which heats up as a result of the fission reactions. In pressurized water reactors (PWR), the water is heated by the tubes containing the fuel and transfers its heat via heat exchangers to a secondary cooling system, where the water is converted into steam. The nuclear steam supply system consists of the reactor core and the steamgenerators, together with the pressurizer, the reactor coolant pumps, and the hot and cold legs connecting the pumps. The primary cooling system is separate from the secondary cooling system, which produces steam to drive the turbo-generator, making radioactive containment that much stronger. PWR reactors have a triple barrier system to prevent the release of radioactive fission products. The primary barrier in this system consists of the metal tubes containing the fuel. The secondary barrier consists of the separate primary and secondary cooling systems. The third barrier is comprised of the nuclear steam supply system enclosed in a concrete containment building capable of containing hazardous products in the event of a leak. All of the reactors in the French nuclear reactor fleet are PWRs, which represent the majority of reactors in service around the world.

BOILING WATER REACTOR

Primary cooling system Steam-water system

Reactor vessel

Steam

Feed water

Generator

Reactor core

Feedwater pump

Condenser

Cooling water

Heater

Control rod drive mechanisms

Reactor water recirculation pumps

Source:AREVA. AREVA is active in both of these reactor systems.

Difference between generation II and generation III reactor systems Nuclear reactor technologies are classified in terms of generation. The timeline for the different generations corresponds to the date at which the related technologies become mature. Most of the reactors currently in service around the world are generation II reactors consisting mainly of PWRs and some BWRs. AREVA’s generation III reactor models are based on evolutionary technology with additional features which factor in operating experience from previous generations of reactors, particularly in terms of nuclear and industrial safety. Renewable energies Renewable energies – hydropower, biomass, wind, solar, geothermal and ocean energies – do not consume natural resources for their operations. Their efficiency is contingent on their location (dam site, wind, sunshine, etc.). Some of these energy sources are spread out and intermittent, which makes them less suitable for centralized baseload power generation. Others aremore flexible and allow relatively high power densities to be achieved. Since the group is refocusing on operations related to the nuclear fuel cycle, AREVA has decided to gradually withdraw from the renewable energies segment. AREVA’s operations in renewable energies are presented in Section 6.4.3.2. Renewable Energies operations.

PRESSURIZED WATER REACTOR

Primary cooling system

Steam generator

Secondary cooling system

Pressurizer

steam

Control rod drive mechanisms

Reactor coolant pump

Generator

water

Reactor core

Feedwater pump

Condenser

Reactor vessel

Cooling water

Reheater

Source:AREVA. Boiling water reactors (BWR) are generally comparable to PWRs. The main differences are that the water boils when it comes into contact with the fuel, and there is only one steam system. The fuel core releases its heat to the water passing through it, which vaporizes at the top of the vessel containing the core. The resulting steam drives the turbine, then cools when it comes into contact with the cold source and is liquefied in the condenser before it is recirculated to the reactor vessel. Thus, in a BWR, the water is in a closed cycle in which the steam produced in the reactor core expands directly into the turbine.

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2016 AREVA REFERENCE DOCUMENT