Areva - Reference Document 2016

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RISK FACTORS

4.4 Industrial and environmental risks

p risks associated with the use of pressurized equipment;

p away from controlled airspace;

p risks associated with utilities (electricity, water, steam, industrial gases, etc.). These risks are managed using an approach similar to that used for nuclear risk management, depending on the nature of the risk and in compliance with regulatory requirements defined for each technical field: safety systems, fire containment, detection, Atex rules for explosive atmospheres, separation of incompatible chemicals, etc. These technical measures are supplemented as necessary by compliance inspections, periodic verifications and maintenance, and operator training and/or certification. Measures are also adopted to minimize the consequences of a failure when an incident may have an impact on nuclear safety. Automatic fire detection systems are used for early alerts to employees trained to respond to and extinguish a fire start. Response means are also provided (e.g. fire department in the event of a fire start). The use of uranium hexafluoride (UF 6 ) is a risk highly specific to the group’s operations Enrichment operations involve the handling of uranium in the chemical form of uranium hexafluoride (UF 6 ), which is solid at normal temperatures and pressures and becomes gaseous when heated (sublimation at about 56°c). This gas can react when it comes into contact with water vapor in the air, forming uranium oxide and hydrofluoric acid, a compound which is highly toxic to humans, plants and animals. In view of the large quantities of UF 6 handled at the production sites, the inherent risks were factored into the design of the facilities (double containment barrier, automated monitoring of high-risk areas, etc.). Other risks, such as those related to parallel activities and to human and organizational factors, are also taken into account. Prior coordination of activities by the parties involved and the establishment of a suitable organization combined with personnel training in particular help limit these risks. Unlike risks of internal origin, it is not always possible to act on risks of external origin related to the facility’s environment. However, their originmust be taken into account to reduce and manage their consequences, particularly in terms of radiation. The desired level of protection is ensured by considering in particular unforeseen but highly improbable events in the context of each site. Earthquake Earthquakes and their possible repercussions, such as a tsunami, can cause damage that could disable nuclear safety systems. For facilities in which nuclear materials are handled, the risk of an earthquake is factored into the design of equipment, systems and buildings. Risk analysis consists of demonstrating that no damage affecting the nuclear safety of the facility is likely to occur for the event scenario considered. Airplane crash This risk concerns the crash of an airplane or part of an airplane on a facility. Its probability of occurrence depends on the number of aircraft that could reach the site without being detected; its potential severity depends on the type of aircraft and the surface area of sensitive areas in each facility. Each site is located: 4.4.1.3. EXTERNAL RISKS THAT COULD LEAD TO NUCLEAR RISK

p away from airspace used by military aircraft; and

p far from any airport. Safety studies are carried out to assess the risk of an airplane crash, including the risk of deliberate attack, and to determine the means for limiting its consequences (factoring in the organization of airspace use, types of flights, known crash statistics, etc.). Special measures are taken to protect nuclear facilities from terrorism. These measures have been strengthened under the French national security plan known as “Vigipirate”. For security reasons, these measures may not be disclosed to the public. Adverse meteorological conditions and flooding This risk is factored into the design based on potential local weather conditions. Advance warning is given for any threatening weather conditions, and there are instructions for each facility concerning additional measures to be taken, such as increased monitoring or specific actions. The possible causes of external flooding (rain, river flooding, breach of levies, tsunami) are factored into the design of the facilities and operating measures. The risk of a thousand-year flood is taken into account, in particular by locating facilities above the thousand-year flood plain. Other risks caused by potential external events, such as the loss of power supply or utilities (water, steam, compressed air, etc.), are addressed through redundant or independent backup systems. Following the accident at the Fukushima Daiichi nuclear power plant in Japan, in addition to measures taken in the design of the facilities or during operations, supplementary safety assessments (SSA) were carried out to evaluate the facilities’ ability to withstand a malfunction. Based on these assessments, special programs to improve the level of facility protection led to work and actions (see Appendix 3, Section 2. Environmental information of the 2015 Reference Document). Other measures are being implemented in accordance with regulatory decisions by ASN applicable to the group’s nuclear facilities. TRANSPORTATION OF RADIOACTIVE MATERIALS To protect members of the public, property and the environment from the effects of radiation during the transportation of radioactive materials on public lands, the “defense in depth” concept applies to these operations, as it does to other nuclear operations. This concept consists of setting up a series of barriers – safety systems, procedures, technical or administrative controls, etc. – to prevent accidents and limit their consequences. The design of the shipping cask is the main component of this system. As with any nuclear activity, these operations are governed by stringent international regulations. If the materials transported exceed a certain level of activity set by regulation, the cask must, under normal and accidental operating conditions, provide: 4.4.1.4.

materials containment;

p

p constant sub-critical conditions when fissile materials are transported;

p control of radiation intensity; and

p protection from the heat of the materials transported to prevent damage.

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2016 AREVA REFERENCE DOCUMENT