Second phase of Nuward review completed

In June 2022, EDF announced that the Nuward design would be the case study for a European early joint regulatory review led by the Autorité de Sûreté Nucléaire (ASN) with the participation of Finland's Radiation and Nuclear Safety Authority (STUK) and the Czech State Office for Nuclear Safety (SÚJB). The review would be based on the current set of national regulations from each country, the highest international safety objectives and reference levels, and up-to-date knowledge and relevant good practice. The main objectives of the multilateral review were to identify key issues towards the hypothetical licensing of a Nuward small modular reactor (SMR) in the three countries, and to identify divergences and convergences between the regulatory frameworks in these countries - it was not intended to replace any future licensing review of any participating regulator.

The six areas covered during the year-long joint early review were: the general safety objectives; the list of design basis conditions and design extension conditions; the use of passive cooling systems; the development plan for computer codes; the integration of two reactor units in a single facility; and the Probabilistic Safety Assessment approach. The three regulators published their report on the first phase of the review in September 2023.

At that time, a second phase of the review was announced, which was joined Poland's National Atomic Energy Agency (PAA), the Swedish Radiation Safety Authority (SSM) and the Netherlands' Authority for Nuclear Safety and Radiation Protection (ANVS).

This second phase built upon the successes of the pilot phase - particularly the work of reviewing a specific project and establishing a direct dialogue with the designer - while evolving to address new challenges, notably broader participation. During the second phase, the scope of the assessment was extended to new technical topics, including: management of extended design conditions; assessment of containment and radiological effects; architecture of electrical systems and measurement, control and management systems; and criticality risk management.

The final report of the second phase, which was published on 2 December, presents the programme carried out, the working methodology implemented, as well as the main lessons learned.

"This second phase confirmed the benefits of such an initiative in enhancing regulators' effectiveness and responsiveness in licensing new reactors," the report says. "In particular, it was a helpful input for members revising their regulatory framework. It also confirmed that most of the identified divergences stem from differences at the guidance level and the way of implementing regulatory requirements but not really from differences in requirements as such.

It adds: "The results confirmed that the joint regulatory approach increases the efficiency of information exchange, accelerates the identification of technical differences and allows to address key safety issues earlier than would be possible under separate national licensing processes. The Joint Early Review thus strengthens the readiness of individual states for future assessment of SMR proposals and at the same time creates space for further harmonisation of procedures in Europe.

"A dedicated forum where regulators can engage with a vendor on a specific reactor design is a highly effective tool for early interactions. It allows safety-related issues to be addressed at an early stage, minimising findings later in the licensing process, while also enabling the deployment of a reactor design across multiple countries through joint regulatory evaluation. Furthermore, such cooperation facilitates practical, in-depth assessment of safety features, making the process both concrete and results-oriented."

"The project has taught everyone involved how safety assessments can be carried out together in practice," said Eero Virtanen, Principal Advisor for STUK. "During the project, we also saw how different interpretations of safety requirements can affect the final design of the nuclear reactor."

ANVS licensing authority Thierry Louis added: "During a real licensing procedure, an initiator has to convince us substantively that they can guarantee nuclear safety. The Joint Early Review gave Nuward the opportunity to discover what fellow regulators are looking for. Conversely, we learned about a modern SMR and benefited from the collaboration with fellow regulators."

Discussions are currently under way to continue the joint review of the Nuward reactor project, focusing on new topics.

The Nuward project

The Nuward project was launched in September 2019 by the French Alternative Energies and Atomic Energy Commission, EDF, Naval Group and TechnicAtome. The Nuward - consisting of a 340 MWe SMR plant with two pressurised water reactors (PWRs) of 170 MWe each - was jointly developed using France's experience in PWRs. The technology is intended to replace old high CO2-emitting coal, oil and gas plants around the world and support other applications such as hydrogen production, urban and district heating or desalination.

According to Nuward's previously announced SMR roadmap, the detailed design and formal application for a new nuclear facility was scheduled to begin in 2026, followed by first concrete in France in 2030 with the construction of that first unit anticipated to take about three years.

However, in July 2024, EDF said that in response to feedback from potential European customers it planned to optimise the Nuward design, focusing on existing and proven technologies, in order to guarantee that project deadlines and budgets are met.

In January this year, Nuward said: "The studies conducted in recent months have been decisive: Nuward has refined its SMR strategy to fully meet the expectations of the utilities and industry. The Nuward SMR will deliver 400 MW of power and offer an option for cogeneration, up to approximately 100 MWt. It will rely on well-known and perfectly mastered technological building blocks within the nuclear sector to offer a safe product adapted to market needs."

The company said the aim now is to finalise the conceptual design of the reactor by mid-2026 and "market a product for the 2030s", with a first-of-a-kind reactor built in France.