Areva - Reference Document 2016

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RISK FACTORS

4.4 Industrial and environmental risks

4.4.1. NUCLEAR RISKS

4.4.1.1. RISKS OF NUCLEAR ORIGIN Risks of nuclear origin relate to the characteristics of radioactive substances. These risks thus concern all of the group’s industrial facilities in which these substances are found, whether regulated nuclear facility, regulated defense nuclear facility, environmentally regulated facility or mining operations. Risk prevention is based on a systemic and systematic analysis of the risks specific to each facility or activity undertaken and on the definition of means for preventing events of concern, for detecting and managing incidents and accidents, and for limiting their potential consequences, based on defense-in-depth principles. These principles involve a systematic analysis of potential technical, human or organizational failures, and definition and implementation of a series of independent lines of defense to protect against the consequences of those failures. These principles are implemented during the facility design phase, during the industrial production phase, and during cleanup and dismantling after the end of production operations. Dissemination of radioactive materials which could lead to contamination Radioactive materials in solid, liquid or gaseous form may disperse and lead to human and environmental contamination if they are insufficiently contained. Controlling this risk consists above all of limiting the dispersion of those substances from the facilities under all operating conditions, both normal and accidental, as well as after shutdown, in particular by interposing suitable containment barriers and ventilation systems. Radiation There is a risk of exposure to radiation whenever a person works in the presence of radioactive materials. The estimated biological impacts of radiation on the human body are generally expressed in millisieverts (mSv). The annual regulatory limits are as follows: p in the European Union, 1 mSv per year for the general public above naturally occurring radioactivity, and 100 mSv over five consecutive years for employees, not to exceed 50 mSv in any one year; p in the United States, 1 mSv per year for the general public and 50 mSv per year for employees; p in France, the maximum regulatory limit for employees is 20 mSv/year. AREVA applies this maximum limit to all of its employees and subcontractors in all of its facilities and operations, regardless of the country in which they are located. Collective protection and monitoring systems are installed to limit radiation at the source and optimize the doses received to levels that are as low as reasonably achievable (ALARA). In addition and if necessary, the working time of operators is limited. The group applies the ALARA principle, which holds that every action will be taken to reduce exposure to radiation as long as it is reasonable from the technical, economic, social and organizational standpoints. The radiation protection departments continually verify compliance with this principle of optimization. After a job study and approval by the occupational health physician, all operators and workers qualified for work in a radioactive environment receive thorough medical and radiological follow-up. Regular training sessions are held to maintain their knowledge at the appropriate level, in accordance with applicable regulations.

The results achieved (see Appendix 3. Social, environmental and societal responsibility ) testify to the effectiveness of these practices and the good level of radiation protection control in the group. Criticality The risk of a criticality accident corresponds to the risk of an uncontrolled chain reaction with a brief and intense emission of neutrons, accompanied by radiation. This risk, should it materialize, would result in irradiation of workers or individuals located near the event, causing lesions proportional in seriousness to the intensity of the radiation received. This risk is addressed in any facility likely to receive fissile materials. The prevention of this risk is based on limiting the factors leading to uncontrolled chain reactions. This limitation is factored into the design (e.g. equipment geometry) or operating requirements (e.g. mass limitation). In areas of facilities representing the greatest risk, prevention measures are strengthened with the use of shielding to sharply reduce the consequences of a potential criticality incident for personnel, and with the installation of a criticality accident detection, alarm and measurement system. For transportation, nuclear safety and criticality under both normal and accidental operating conditions are verified. Transportation regulations set forth rules for storage during transit, particularly in terms of the criticality risk. Thermal releases and radiolysis Matter absorbs the energy produced by intense radiation, which can lead to increase temperatures. The energy is removed to control the temperature increase and prevent the dispersion of radioactive materials. Cooling is provided by redundant cooling systems with heat exchangers and ventilation systems. Radiolysis corresponds to the decomposition of a hydrogenated compound (especially water) when exposed to radiation, leading to the release of hydrogen. In normal operations, the facilities are designed to limit hydrogen concentrations by flushing the equipment with air. A backup system is added if a loss of normal flushing capacity can cause concentrations to rise to the limit value in a few hours or tens of hours. As in any industrial activity, facility operations and the presence of personnel also give rise to risk. Since such incidents could affect equipment important to nuclear safety, strong prevention measures are taken in the nuclear industry. Prevention is based on factoring the potential causes of malfunctions into the design or operating instructions and on limiting their possible consequences. The most frequently encountered conventional risks are: p risks associated with the handling and use of hoisting, transfer and positioning equipment; 4.4.1.2. INTERNAL RISKS THAT COULD LEAD TO NUCLEAR RISK

p risks of fire and internal explosion;

p risks related to the use of chemical reagents or toxic raw materials such as HF or UF 6 ;

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2016 AREVA REFERENCE DOCUMENT