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1.3 The back-end fuel cycle:
fabrication of MOX fuel
The Mélox uranium and plutonium-based
fuel fabrication plant
BNI 151 Mélox, situated on the Marcoule nuclear site,
operated by Areva NC, is today the world’s only nuclear
installation producing MOX fuel, which consists of a
mixture of uranium and plutonium oxides.
The facility’s periodic safety review file was sent by the
licensee on 21st September2011. One of main issues
which came out of the review was controlling worker
exposure to ionising radiation and adaptation of the
facility and its organisation to changes in the composition
of the materials used. In its resolution of 15th July
2014, ASN stipulates that continued operation of the
plant is dependent on compliance with the prescriptions
for controlling the risk of worker exposure to ionising
radiation, the criticality risk and the risk of fire. It in
particular prescribes the oversight of the measures
identified during the review and the undertakings
made by the licensee.
In 2012, Mélox submitted an application for authorisation
to implement an internal authorisations process. This
authorisation was granted by the ASN resolution of
23rd September 2014.
In 2015, ASN observed that the safety situation in the
facility is on the whole satisfactory. The containment
barriers remain effective, the radiation protection and
criticality risk control issues are dealt with rigorously.
However, ASN did observe that monitoring of
subcontracted operations needs to be significantly
improved. ASN also observed that the management of
equipment subject to pressure equipment regulations
was inadequate, which led Areva NC to implement a
programme to guarantee compliance.
The licensee has expressed its aimof producing a limited
quantity of experimental fuels in the coming years, to
qualify new types of fuels for the possible construction of
fast neutron reactors. This operation is not authorised by
theMélox Creation AuthorisationDecree andwould need
to be the subject of a modification of the authorisation
decree covering this facility.
2. INTEGRATION OF EXPERIENCE
FEEDBACK FROM THE FUKUSHIMA-
DAIICHI ACCIDENT
All of the fuel cycle facilitieswere dealt with as a priority in
the light of the experience feedback fromthe Fukushima-
Daiichi accident. The licensees supplied stress test reports
in September 2011 for all facilities and sites, with the
exception of BNI 63 (Cerca), for which the report was
submitted in September 2012.
In its resolutions of 26th June 2012, ASN set additional
prescriptions for theArevaGroup facilities assessed in2011,
in the light of the conclusions of the stress tests. These
prescriptionsmore specifically require the implementation
of a “hardened safety core” of material and organisational
provisions designed to prevent a severe accident or limit
its spread, mitigate large-scale releases and enable the
licensee to fulfil its emergency management duties. The
licensee is more specifically required to propose the level
characterising the extremenatural hazards tobe considered
in the design and sizing of the “hardened safety core”
equipment.
ASNreviewed the proposals fromtheAreva group todefine
the “hardened safety core” and its functions, including for
the Areva NP BNI 63 in Romans-sur-Isère.
The ASN resolutions of 9th January 2015 prescribe
the hazard levels and associated requirements for the
“hardened safety core” and the deadlines for deployment
of this “hardened safety core” for all cycle installations.
The reference earthquake was in particular defined in
it, based on an earthquake liable to occur every twenty
thousandyears.Thecurrentstateofknowledgeinseismology
makes it particularly difficult to characterise such events,
whereas the design of industrial facilities presupposes a
precise definition of the loadings the facilitymust be able
towithstand. Even if a reference earthquake has todaybeen
characterised for the “hardened safety core” at La Hague,
technical discussions are continuing for the other Areva
sites at Romans-sur-Isère, Marcoule and Tricastin. With
the aimof ensuring consistency and stringency, ASN thus
allowed more time for the technical debate and will rule
in 2015 on the levels to be adopted by all the licensees.
Similarly, ASNwill decide on the definition of the tornado
risks tobe considered for the components of the “hardened
safety cores” of all French nuclear facilities in 2016.
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CHAPTER 13:
NUCLEAR FUEL CYCLE INSTALLATIONS
ASN report on the state of nuclear safety and radiation protection in France in 2015