An engineer in the electrical engineering field, Charles has worked in the field of equipment qualification for nuclear facilities since 2017.
Equipment qualification is a major challenge for the New Nuclear Power Plant, but also for major maintenance operations on operating facilities (known as "Grand Carénage"). Excellent control of the qualification process is essential to successfully qualify equipment while optimizing time and costs.
In any operating nuclear power plant, some equipment is classified as “Important to Safety” (ITS). It is therefore essential to ensure that they function properly under all the ambient and environmental conditions for which they are required. They must therefore be qualified (by testing, analysis, calculation, etc.) before installation, in order to guarantee that they will function correctly throughout their lifetime.
The nuclear operator is responsible for this qualification, a process that can be carried out either by the operator itself, or subcontracted to equipment suppliers or external service providers like Assystem. It all depends on how the nuclear operator contracts for its project.
The two main types of qualification
Initial qualification of equipment mainly concerns new nuclear facility projects, such as the Flamanville EPR, the Hinkley Point EPR in the United Kingdom, the Jaitapur EPR in India, EPR2 or the ITER project at Cadarache.
Progressive qualification refers to the extension of the lifetime of power plants (Grand Carénage) beyond the 4th ten-yearly inspections (about 40 years). "The exercise consists in setting up a strategy, most often using materials taken from the site (at the end of their qualified life), to establish a qualification line representative of the desired life extension; most often 10 years. The conclusions will make it possible to indicate the components to be replaced as well as the points of attention to be taken into account to extend the service life without risk to safety."
The progressive qualification process will make it possible to justify the possibility of keeping certain equipment beyond their initial qualified life span
The poor control of the process and/or the failure of a test has a major impact on the planning for the new nuclear power plant and a financial impact for the Grand Carénage.
Lessons learnt from the FA3 new build mega project
The Flamanville 3 (FA3) EPR – currently under construction by EDF in the Manche department, is a perfect illustration of the challenges of the qualification business and its impact on a major industrial project. As a new mega-project, with no previous experience or recent references, from the start, the difficulty lay in:
- the volume and duration of the qualification work (some 400 items of equipment); and
- the lack of experience of some of the suppliers carrying out the process.
As a result, some qualification files were late and incomplete. They had to be revised, and the reworking of a qualification file can delay the qualification of the equipment by at least one year, especially if tests have to be carried out again; all these elements explain the impact of the delay...
"We realize that qualification is not to be taken lightly and that it is essential that all suppliers master the qualification process perfectly or, failing that, that they receive support to carry it out," says the technical referent.
Each to their own job: a win-win approach
In the EDF/DIPDE client case, the approach chosen was to bring together all the trades involved to develop and qualify a new piece of equipment. Thus, in 2018, EDF/DIPDE launched an invitation to tender for the study, design, qualification, supply and turnkey installation of a high-voltage source inverter cabinet to supply the spray pump for the 900 MW unit.
EDF wanted the design of a new equipment by an industrial expert in its technical field. In this context, AMC ETEC, an SME specializing in the design and production of electro-intensive circuits but with no experience of nuclear power, joined forces with SPIE, a historic player in the nuclear industry, and called on Assystem to help it carry out the qualification process for its source inverter cabinet.
Assystem's mission includes studies related to the qualification of the inverter (from the definition of the qualification strategy to the validation of the laboratory tests), reliability and maintainability studies of the inverter, while ensuring the associated transverse support (drafting of test non-conformity sheets, contracting of the tests with the laboratories...).
The first phase aimed to limit the risks of failure of the qualification test campaign itself. To this end, seismic and short-circuit resistance tests were successfully carried out, thus validating the design chosen for the equipment. The next step will be a complete campaign of qualification tests, on which the Qualification Summary Note (QSN) will be based.
The common goal is to have a prototype that has successfully passed all the tests intrinsic to high-stress operation in a nuclear power plant by the end of 2022.
This example clearly illustrates the contribution of a Qualification "pole" with an industrialist who is an expert in his technical field but has no experience of nuclear power, for the development of equipment for the benefit of the nuclear operator.
An industrial player with no nuclear experience was able to develop and successfully qualify equipment
Another example of successful qualification is the industrial mixer for the CEA.
For its STEMA installation, the CEA had to replace the process of blocking active sludge from the STEL (Station d'Effluents Liquides) of Marcoule in bitumen by a blocking in a concrete matrix. The CEA had chosen EIRICH, a company specialized in industrial mixers but with no experience in the nuclear field. Following the technical proposal of Assystem, they decided to trust the expertise of Assystem to accompany the supplier to nuclearize the STEMA mixer and to be in conformity with the requirements of the ANDRA. We defined the requirements for which the mixer had to be designed, such as compliance with safety requirements (seismic resistance, dynamic mixer ventilation, fire risk linked to the mixer motor), choice or protection against irradiation of mixer components, means to avoid dispersion of material outside the conditioning drum via a tight docking, feasibility of mixer maintenance.
Assystem then deployed several complementary qualification methodologies: by calculation for static/dynamic and seismic sizing, by calculation for the fire extinguishing system, by specifications for procurement/manufacturing/assembly/testing of mixer components, by carrying out on-site tests, etc.
Thus, thanks to Assystem's engineering skills, an industrial company with no experience in the nuclear industry was able to successfully develop and qualify equipment that met the specific needs of the CEA.
Equipment qualification – a profession in its own right
Once the qualification requirements have been determined and the equipment to be qualified has been defined, the first step is to determine the qualification strategy, which can be demonstrated either by analysis, or by tests (on model equipment to be determined), or by the mixed method (analysis and tests). The chosen strategy is detailed and justified in the qualification program (written by the supplier if it is his responsibility), which the operator must validate. "Entrusting the qualification to the qualification center as soon as the strategy is established reduces the risk of failure due to poor representativeness of the model material or to avoid qualifications by analysis that turn out to be impossible," he insists, while recommending that the materials that present the greatest risk of failure in tests be prioritized from the start. Indeed, a major "non-conformity" observed during the last tests of the test line can lead to a modification of the equipment design and then to the resumption of a new complete test campaign; this scenario considerably lengthens the time required to qualify the equipment, given that a complete qualification campaign can last from 6 to 18 months..
The goal of the qualification strategy is to define the qualification campaign as accurately as possible before it is launched, in order to optimize its duration and reduce the risks associated with a failure or lack of prior analysis.
Assystem thus considers qualification as a business in its own right. Carrying out this activity in the design office encourages synergies between the various engineers and the different projects handled and makes it possible to gain in efficiency. "This makes it possible to optimize the overall process, hence the interest in calling on qualification specialists. These engineers can then respond either to the needs of the nuclear operator who is short of resources (to help supervise the qualifications or to carry them out if they are done in-house); or to the needs of the equipment suppliers. But of course never both for a given project and the same equipment."
In relation to FA3, we can see the relevance of the existence of such a skills cluster. "Assystem's qualification center brings together all the skills and feedback needed to successfully complete any qualification, from the qualification strategy, for the representativeness of the model equipment, to the drafting of the Qualification Summary Note (QSN) that pronounces the qualification."
Digital solutions to boost effectiveness: moving towards augmented qualification
The qualification phases result in a strong multi-business knowledge coupled with the processing of a volume of heterogeneous data and a very complex scheduling of activities linked to a multiplicity of actors and interfaces.
This business/data/project execution complexity is taken into account by the new organization presented in the previous paragraphs, coupled with system modeling and a document-centric approach, which will improve the qualification processes and reduce the completion times as well as the impacts on project delivery.
The automation of tasks is difficult in the qualification domain. This difficulty comes mainly from the fact that the input data defined for the realization of a qualification are sometimes incomplete, only a team with a seasoned eye will be able to delimit in an exhaustive way the perimeter of the qualification process.
Nevertheless, Assystem's qualification team seeks to automate the work where possible; this is the case for the Hard Core seismic re-evaluation. Thanks to our expertise in earthquake resistance, we have set up algorithms allowing comparisons of seismic spectra according to databases provided by EDF and completed by Assystem. This automation allows to improve the costs and delays of seismic re-evaluation projects as well as to facilitate and make reliable the analysis of seismic spectra.