RISK FACTORS
04
4.4 Industrial and environmental risks
p
risks associated with the use of pressurized equipment;
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.
4.4.1.3.
EXTERNAL RISKS THAT COULD LEAD
TO NUCLEAR RISK
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:
p
away from controlled airspace;
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.
4.4.1.4.
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:
p
materials containment;
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.
2016 AREVA
REFERENCE DOCUMENT
23