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The aim of the strategy adopted in France is that:
•
the licensee prepares the decommissioning of its
installation from the design stage;
•
the licensee anticipates decommissioning before its
installationstopsoperatingandsendsthedecommissioning
authorisation application file before its installation is
shut down;
•
thedecommissioningoperationsarecarriedout“inasshort
a time as possible” after shutting down the installation, a
time which can vary from a few years to a few decades,
depending on the complexity of the installation.
1.2.2 Complete clean-out
The decommissioning and post-operational clean-out
operations for a nuclear installation must progressively
lead to elimination of the radioactive substances
resulting from the activation phenomena and/or of
any contamination deposits or migrations, in both the
structures of the installation premises and the ground
of the site.
The structure clean-out operations are defined on the basis
of the prior updating of the facility’s waste zoning plan
which identifies the areas in which the waste produced
is, or could be, contaminated or activated. As work
progresses (for example after cleaning the surfaces
of a room using appropriate products), the “possible
nuclear waste production areas” are downgraded to
“conventional waste areas”.
Pursuant to the provisions of Article 8.3.2 of the BNI Order,
“the final state reached on completion of decommissioning
must be such that it prevents the risks or inconveniences that
the site may represent for the interests mentioned in Article
L. 593-1 of the Environment Code, in viewmore particularly
of the projections for reuse of the site or buildings and the best
post-operational cleanout and decommissioning methods
available under economically acceptable conditions”.
In
this context, ASN recommends, in accordance with
its decommissioning policy developed in 2009, that
the licensees deploy clean-out and decommissioning
practices taking into account the best scientific and
technical knowledge available at the time and under
economically acceptable conditions, with the aim of
achieving a final status in which all the hazardous and
radioactive substances have been removed from the
BNI. This is the reference approach according to ASN.
Should it be difficult to apply this approach due to the
nature of the contamination, ASN considers that the
licensee must go as far as reasonably possible in the
clean-out process. Whatever the case, the licensee must
provide technical or economic elements proving that
the reference approach cannot be applied and that the
clean-out operations cannot be taken further under
acceptable economic conditions using the best technical
clean-out and decommissioning methods available.
In accordance with the general principles of radiation
protection, the dosimetric impact of the site on the
workers and public after decommissioning must be
as low as possible. ASN therefore considers that the
defining of a priori thresholds cannot be envisaged. More
specifically, achieving a threshold with an exposure level
leading to an annual dose of 300 µSv for the workers or
the public does not, in principle, constitute an acceptable
objective.
ASN is working on the updating of its technical guide
relative to structure clean-out operations (Guide No.14,
available on
www.asn.fr) with a view to publication in
2016. It had been issued in 2010 in draft form pending
publication of the Order of 7th February 2012 and the
resolution on the study of management of the waste
produced in basic nuclear installations. The provisions of
this guide have already been implemented on numerous
installations with diverse characteristics, such as research
reactors, laboratories, fuel manufacturing plant, etc.
In 2015, ASN also produced a draft guide on the
management of polluted soil in nuclear installations.
It was made available to the stakeholders for consultation
in view of publication in the first quarter 2016.
1.3 Decommissioning regulatory
framework
From the moment a BNI is definitively shut down, it
must be decommissioned and therefore changes its
purpose with respect to that for which its creation
was authorised, as the creation authorisation decree
specifies, among other things, the operating conditions
of the installation. Furthermore, the decommissioning
operations imply a change in the risks presented by the
installation. Consequently, these operations cannot be
carried out within the framework set by the creation
authorisation decree. The decommissioning of a nuclear
installation is prescribed by a new decree issued after
consulting ASN. This decree sets out, among other things,
the main decommissioning steps, the decommissioning
end date and the final state to be attained.
In order to avoid fragmentation of the decommissioning
projects and improve their overall consistency, the
decommissioning file must explicitly describe all the
planned operations, from final shutdown to attainment
of the targeted final state and, for each step, describe the
nature and scale of the risks presented by the facility as
well as the envisaged means of managing them. This
file is subject to a public inquiry.
Given the fact that installation decommissioning
operations are often very long, the decommissioning
decree can stipulate that a number of steps will, when
the time comes, be subject to prior approval of ASN
on the basis of specific safety analysis files (previously
called “hold points”).
The diagram below illustrates the corresponding
regulatory procedure.
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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