The safety of advanced reactors

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Álvaro Acevedo discusses the security challenges facing advanced reactors and the work carried out by the World Institute for Nuclear Security.


OVER THE PAST YEARS, THERE IS A growing interest in advanced reactor designs to provide carbon-free power for a range of commercial applications that go beyond the mere provision of electricity. Advanced reactors can also address some of the long-term challenges of nuclear technology, including costs and competitiveness, potential proliferation issues, waste, safety and security.

The World Institute for Nuclear Security (WINS) believes that building stakeholder confidence is vital for the implementation of these technologies. It has published a special report on the safety of advanced reactors which is based on more than 20 interviews with developers, regulators and subject matter experts.

The report provides an overview of the international environment in the deployment of advanced reactors, examines the safety considerations and challenges of various reactor designs, and recommends “safety by design” methodologies.

International perspective and regulatory issues

The report provides a high-level perspective of the available international instruments, standards and guidance that shape national regulations and laws relating to advanced reactors.

WINS recognizes that the International Atomic Energy Agency (IAEA) is the primary international organization providing relevant guidance to developers and has two key documents on this subject. The first is the IAEA Nuclear Security Series (NSS) 13, which provides general guidance on physical protection and interfaces with nuclear material safety and accounting and control activities. The IAEA also provides comprehensive guidance on NSS 35G (Safety During the Lifespan of a Nuclear Installation) and suggests integrating nuclear security from the initial design phase and integrating security into safety measures, guarantees, operational and others.

Two international working groups are assessing the viability of advanced reactors in a number of areas, including physical protection. The first is the International Project on Nuclear Reactors and Innovative Fuel Cycles (INPRO), and the second is the Proliferation Resistance and Physical Protection Working Group.

WINS interviewed officials from three regulatory bodies to understand common challenges in their approach to developing regulations and licensing these advanced reactors. They examine a performance-based approach with fewer requirements, which recognizes that advanced reactors may require a flexible and technologically neutral approach to cope with the large variations between different reactor designs. They recognize the importance of emerging technologies and threat capabilities, especially cybersecurity, a new and evolving threat that will require an update of the regulatory framework.

Safety Considerations for Advanced Reactor Designs

One of the main goals of the WINS Special Report is to encourage developers of advanced reactors to integrate “safety by design” as early as possible. Developers must first understand the safety considerations for advanced reactor designs. WINS research has revealed that the risk of theft or sabotage depends on the amount of material used and the frequency of refueling, which varies depending on the technical characteristics of the reactor. All of these considerations will affect safety.

Some designs will be less susceptible to overheating and core damage, as they will use passive safety features and rely less on external power. Some designers incorporate technical physical protection systems into their designs, such as siting underground to defend against potential scenarios such as a plane crash.

According to WINS research, developers see the cost of licenses as a major concern. This means that developers can only offer optimization for security provisions that do not compromise safety or security. This is made even more difficult because the incorporation of safety features similar to those required by traditional nuclear power plants in the design of the reactor is not economical, mainly in terms of operation and maintenance costs. Developers interviewed by WINS say the improved safety characteristics of advanced reactors should form the basis for demonstrating risk-informed safety requirements.

The developers also say automation is an important design goal. The automation of safety and security will make the operation of reactors more economical. This can dramatically reduce human error and the potential for insider threats. Likewise, the inclusion of robotic technologies such as drones can reduce costs by reducing the number of security personnel. Advanced technologies could improve threat detection.

During its research, WINS was able to map the following different security challenges:

  • Low enriched uranium in high dosage (HALEU) and the supply chain. HALEU is enriched between 5% and 20%. Some developers interviewed by WINS are concerned about the differentiation between LEU and HALEU. The description of HALEU introduced confusion as to its categorization for physical protection purposes.
  • Remote implantation. A significant number of advanced reactor designs such as heat pipe reactors are intended for use in remote sites and at sea. Difficult access to these remote sites can have safety advantages and disadvantages. Problems can include effective cyber teams or response teams.
  • Transport. Some reactor designs will include fuel and in others the fuel will be transported separately. It is important for the designer to consider transportation during the fuel cycle, including during decommissioning.
  • Cyber ​​security. The approach taken to tackling cybersecurity is no different from the one that exists. Advanced reactors are not particularly unique from a cybernetic point of view beyond the potential for remote implantation.

Safety by design for advanced reactors

Safety by Design requires that safety be an integral part of the design from the start. It is a risk-informed approach that requires a clear security strategy and a commitment to making security a primary design consideration alongside nuclear safety. It also requires a coordinated approach from all parties, including operators, project managers and regulators.

The key principles of security are deter, deny, detect and delay. We can add design to it. These principles can reduce the risk of a major security incident. Although the initial design costs may be higher, “Safety by Design” will help reduce the cost of preventing a nuclear security incident, and the savings will accrue over the life of the reactor. advanced.

The steps towards developing a holistic ‘safety by design’ approach are as follows:

  • Configure your organization. “Security by design” can only work if your organization is configured to implement it. Everyone, from the CEO to the bottom, must see safety as an integral part of the organization.
  • Understand the threats and consequences. Understand the threats your advanced reactor facility could face, including unauthorized removal of materials and sabotage.
  • Establish your design goals. Depending on the possible threats to your installation and the resources you have available to manage them.
  • Develop your protection model. There are many design solutions available to meet your security goals. The choice will depend on what you are protecting, their status, the nature of the threat, and the resources available.

WINS recognizes the existence of other methodologies, but its special report recommends three comprehensive methodologies and provides detailed “security by design” guidance for developers. The starting points include: the Security by Design manual (Sandia National Laboratories); Secure by Design (a guidance document developed by Adrian Prior and Robert Barnes in the UK); and an assessment methodology (developed by the Gen IV Proliferation Resistance and Physical Protection Working Group). The latter identifies a set of challenges, analyzes a system response to those challenges, and evaluates the results of a proposed design. The characteristics of advanced reactor systems (technical and institutional) are used to assess the response of the system and further determine its resistance to proliferation threats and robustness to threats of sabotage and terrorism.

Preparation is the key to reaping the benefits

Lower costs, less maintenance, and easier operations are strong incentives to use advanced reactors in a wide range of environments and geographic locations. Advanced reactors are inherently safer than operating commercial nuclear power plants, could be located closer to densely populated areas, and provide power where it is needed. Their flexibility means that they could play a key role in the emerging market for decentralized electric power.

As confirmed by the WINS report on the safety of advanced reactors, their safety implications should be identified and addressed as early as possible, as design and technological choices will affect the risk picture and may require changes in the process. regulatory approach.


Author Details: Alvaro Acevedo is Program Manager at the World Institute for Nuclear Security



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