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1. TECHNICAL AND
LEGAL FRAMEWORK
FOR DECOMMISSIONING
1.1 Decommissioning risks
Theriskspresentedbythefacilitywheninoperationchange
asitsdecommissioningprogresses.Evenifcertainrisks,such
as criticality, quicklydisappear, others, suchas those related
to radiation protection or conventional safety (numerous
contractorsworking together, falling loads,workat height,
and so on) gradually become more significant. The same
goes for the fire or explosion risks (due to the cutting up
of structures using thermal techniques that generate heat,
sparks and flames).
The decommissioning of a facility leads to the production
of large volumes of waste which must be properly
managed to limit the risks relating to safety and radiation
protection.
ASN also believes that management of the waste resulting
from decommissioning operations is crucial for the
smooth running of the decommissioning programmes
(availability of disposal routes, management of waste
streams). This subject receives particular attention when
evaluating the overall decommissioning strategies and
the waste management strategies established up by the
licensees at ASN’s request.
Decommissioning operations can therefore only
begin if appropriate disposal routes are available for
all the waste liable to be produced. The example of the
decommissioning of EDF’s first-generation reactors is
a good illustration of this problem (see point 2.1.4).
T
he term
decommissioning covers all the technical and administrative activities
carried out following the final shutdown of a nuclear facility, in order to achieve
a final predefined status in which all the hazardous and radioactive substances
have been removed from the facility. These activities can include, for example,
equipment dismantling operations, post-operational clean-out of premises and
ground, destructionof civil engineering structures, treatment, packaging, removal anddisposal
of waste, whether radioactive or not. This phase in the life cycle of the facilities is characterised
by rapid changes in the state of the facilities and changes in the nature of the risks.
In2015, about thirty nuclear installations of all types (electricity generating or research reactors,
laboratories, fuel reprocessing plants, waste treatment facilities, etc.), were shut down or were
undergoing decommissioning in France.
Decommissioning operations are usually long-termundertakings that represent a real challenge
for the licensees in terms of projectmanagement,maintaining skills currency and coordinating
the various types of workwhichoften involvemany specialised companies. The risks associated
with nuclear safety and radiation protection must be considered with the necessary rigour,
in the same way as the conventional risks associated with any construction site and the risks
linked to the loss of the design and operating memory due to the long duration of this phase,
which often lasts more than ten years. The size of the current French nuclear fleet, which will
have to be decommissioned at the end of its operating cycle, and the ongoing debates on the
energy transition make decommissioning a major challenge for the future, to which all the
stakeholders must devote sufficient resources.
The regulations relative to the decommissioning of Basic Nuclear Installations (BNI) were
clarified and supplemented as of 2006 through Act 2006-686 of 13th June 2006 relative to
Transparency and Security in the Nuclear field, which is now codified, and then through the
Decree of 2nd November 2007 and the Order of 7th February 2012. ASN is continuing the
development of the regulatory framework and the doctrine applicable to this phase of the
BNI life cycle.
The year 2015 saw the delicensing of two installations: the Siloé reactor inGrenoble in January,
and the LURE (Electromagnetic Radiation Laboratory) in Orsay in December.
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CHAPTER 15:
SAFE DECOMMISSIONING OF BASIC NUCLEAR INSTALLATIONS
ASN report on the state of nuclear safety and radiation protection in France in 2015