“From the point of view of safety and radiation protection, the impact on installations and transports of the French fuel cycle of the current fuel management of reactors and envisaged until 2030, does not show any major technical difficulty for this period,” L'Institut de Radioprotection et de Sûreté Nucléaire (IRSN) said in a report of 24 October.
IRSN, set up in 2001, is a public authority under the joint authority of the Ministries of Defence, the Environment, Industry, Research, and Health. It is France’s public service expert in nuclear and radiation risks, and its activities cover all the related scientific and technical issues.
The report adds that its study of prospective scenarios for the evolution of the nuclear power park as defined in the Energy Transition Law for Green Growth (TECV), shows that the shutdown of reactors loaded with mixed oxide (Mox) fuels may lead to “a short-term saturation of spent fuel storage”. The report is the result of a process which began in 2016. At the request of France's Nuclear Safety Authoirty (ASN), since 2000, EDF periodically transmits an "Impact Cycle" file, written jointly with fuel company Orano, nuclear company Framatome, and nuclear waste agency Andra. This presents the consequences, at each stage of the cycle, of EDF's strategy of using the different types of fuel in its reactors over the coming ten years. In June 2016, EDF submitted its "Impact cycle 2016" and IRSN sent ASN the conclusions of its expertise on this in May 2018. These conclusions were then presented to ASN's permanent group of experts.
IRSN's examination focused on:
• Adaptation to needs and changes that may occur in the short or medium term (fuel switching, installation evolution, etc.), means (production or storage facilities, logistical means, etc.) involved in the fuel cycle operation;
• The study of different reactor operating scenarios, including scenarios for reducing the share of nuclear power to 50% of electricity production by 2025, in accordance with TECV;
• The study of hazards for each stage of the cycle, with identification of associated solutions;
• The analysis of major inflections and changes that may appear by 2040.
IRSN underlined the importance of examining the impact of the shutdown of reactors on the overall operation of the fuel cycle.
ASN had previously, on 18 October, published its own opinion on the coherence of the nuclear fuel cycle. It concluded that, to avoid the over-saturation of existing storage capacities over the next decade (reactor pools and La Hague), any reduction in production by reactors consuming Mox fuel must be accompanied by a decrease in the use of enriched natural uranium fuel so that all spent fuel can be processed. This would help reduce inventories and would also solve a potential problem caused by increased stocks of plutonium from the reprocessing of spent fuel as plutonium cannot be stored for any length of time because fission products accumulate.
In the longer term, new storage capacities will be needed “that are significantly higher than the current and projected volume” unless Mox fuel is used in reactors other than the older 900MWe units. Developing these options will require “delays in the order of a decade” and ASN “is therefore asking industrialists to study these two options”.
Orano is the only company in France producing Mox fuel. Its Melox plant in Marcoule produces enough Mox each year to supply 25 to 30 reactors as a supplement to enriched natural uranium fuels. Orano says Mox conserves uranium resources, reduces the quantity of final waste generated by the nuclear industry by five and provides a use for plutonium, which would otherwise accumulate. Orano says the use of Mox fuel “keeps plutonium inventories in balance”. Mox has been used in France since 1987. In 2017, 22 of the 58 French reactors were using mox and 24 more had permission to use it.
ASN asked EDF to considered various scenarios for future nuclear generation over the 2016-2030 period, and their consequences. EDF’s "reference" scenario, assumes nuclear generation will be constant at 420TWh/year, with the transition in 2018 from 22 to 24 reactors using Mox, and with no reactor shutdown. This leads to a saturation of spent fuel storage capacities shortly after 2030.
EDF’s second scenario supposes a decrease in 2020 of nuclear generation from 420 to 408TWh/year, a transition to 2018 from 22 to 24 reactors using Mox, and the shutdown in 2020 of two reactors. This reduces the amount of fuel reprocessed, resulting in saturation of spent fuel storage around 2025.
The third EDF scenario assumes a progressive decrease between 2016 and 2025 of nuclear electricity production from 420 to 306TWh/year through the progressive shutdown of ninetreen 900MWe reactors, 13 of which use Mox. This significant decreases the amount of fuel reprocessed, resulting in saturation of storage capacities less than five years after shutdown of the first reactor.
The fourth scenario envisages the progressive decrease between 2016 and 2025 of the nuclear electricity production from 420 to 288TWh/year by phasing out fifteen 1300MWe reactors.
ASN stressed the need to anticipate for at least ten years any strategic evolution of the fuel cycle operation, “so that it can be designed and implemented under controlled safety and radiation protection conditions”. In particular it stressed the need to ensure that, “given the unavoidable delays in the development of industrial projects, the need to create new spent fuel storage facilities or transport packaging is sufficiently anticipated”.
ASN stressed that, irrespective of the evolution of the reactor fleet, the proportion between reactors consuming Mox and reactors consuming conventional fuel “needs to be maintained over the next decade at a level close to or at its current level” so that all used uranium fuels are reprocessed and the resulting plutonium is consumed. ASN further says the use of mox in 1300MWe reactors should be considered. However, “given the volume of studies to be conducted and the changes to be made to ensure the safety of their operation with this new fuel, the delay between the decision of the manufacturer and its implementation is in the order of the decade”.
EDF plans, by 2030, to commission new pool storage for both Mox and uranium fuels. ASN says this deadline is close to the date for saturation of storage capacities estimated in the EDF reference scenario. “ASN considers it necessary to present the difficulties envisaged in the event of a delayed commissioning of the centralised storage pool.” It also says the consequences of an extended shutdown of reprocessing at a La Hague plant will have to be revalued.