The NEA Strategic Plan 2023-2028 highlights that small modular reactors (SMRs) are viable options to address long-term energy security and environmental challenges for both nuclear and non-nuclear countries. As with any nuclear technology, radiological protection is fundamental to its safe deployment and operation. The diversity of SMR designs and the potential for innovation in the design, regulation and operation of these facilities provide an opportunity to examine the approach to radiological protection.
On this basis, the Committee on Radiological Protection and Public Health (CRPPH) decided at its annual meeting held in March 2022 to establish the Task Force on SMRs to assess and report on whether there are areas of added value for CRPPH-led work concerning radiological protection issues of SMRs. The CRPPH asked the Task Force to provide a brief high-level analysis report on radiological protection challenges related to safety, licensing and operational issues of the deployment of SMRs.
From October 2022 to Mach 2023, the Task Force on SMRs, comprised of 15 experts nominated by 6 NEA member countries and one invitee from an international organisation, met several times to discuss the radiological protection aspects of SMRs and the challenges associated with their development, deployment and operation. The Task Force produced a high-level analysis and identified eight challenges, to be considered for further exploration by the CRPPH.
Eight radiological protection (RP) challenges[1] were selected from a preliminary list identified by the Task Force members. A template was used to describe each of these in a standardised manner by answering two questions: What are the associated RP challenges? What are the benefits of further exploring these challenges? The following summarises the high-level analysis of the challenges identified.
Small compact design: The compact design and modular construction of SMRs can potentially reduce costs and build times. However, such innovation comes with trade-offs on the range of radiological protection impacts that need to be managed. These may include a potentially higher gamma and neutron flux and higher activation levels of materials, loss of access to areas of the nuclear island, limited working space, issues with control of contamination, reduced shielding, and reduced space and distance for maintenance, all of which could pose challenges for managing worker dose during routine operations and potential emergencies. Addressing the challenges associated with the small compact design of SMRs could reduce worker dose and the generation of radioactive materials. For example, measures could be identified to reduce the neutron activation levels, coolant corrosion, fuel leakage, core inventory, and consequently, radiation risk to workers.
Source terms: A better knowledge of the potential source terms associated with the different SMR designs is required in order to understand the associated occupational, environmental and public exposures and the potential impact on a variety of regulatory and operational issues. Of particular interest are the different chemical and physical properties of the fuel, the potential for higher burnup rates and enrichment, new postulated initiating events of incidents, novel materials for the reactor design, smaller piping, and the lack of safety class filtered ventilation and other active containment systems in certain designs that would modify the source term. It is imperative to understand the implications of SMR source terms on radiological protection. Addressing this challenge could reduce uncertainties in human health and environmental impact assessments, enhance safety, help to optimise emergency preparedness and response, and improve RP practices.
Environmental impact assessments (EIA): EIA requires an understanding of, among other factors, the nature of the releases that can be expected, the release pathways, and the media through which they will travel to reach environmental compartments and enter the food chain. Given the anticipated variety of designs, deployment strategies, and novel siting environments, it could be challenging to assemble and validate all of the information required for different projects and to update models as appropriate, especially those in more remote or extreme environments. In some situations, it will be valuable to incorporate the knowledge of indigenous communities into EIAs, which may require adjustments to standardised approaches. If the challenge is addressed, it could increase protection of the environment, reduce uncertainty in analysis, improve regulatory efficiency, and promote public trust. It could also encourage collaborations to share experiences and data, including joint efforts to collate information, such as radionuclide transfer parameters for so far unconsidered environmental media, flora and fauna. Exploring this challenge could contribute to optimised scoping of EIAs for different types of SMR deployment, including appropriately considering safety features and non-radiological risks and benefits. Providing publicly accessible materials that address open questions about different kinds of SMR technologies might help facilitate effective dialogue with stakeholders.
Siting: Careful consideration needs to be given to the siting of new nuclear technologies, particularly where novel sites are being considered. Site-specific factors can affect the setup of a facility, its operation and potential impacts and benefits to the local area. Regulatory factors associated with licensing a site include geographic conditions, proximity to population centres, and site factors affecting public dose (e.g. topography, meteorology), discharges to the environment and emergency response. The public dose criteria and extent of siting analysis developed and used for licensing large reactors may not be the most appropriate for SMRs. In addition, guidance for applying a graded approach to SMR siting is currently lacking. Guidance should provide siting considerations specific to SMRs and propose approaches to meeting regulatory siting criteria. Additional guidance could also be developed to provide a framework for discussion and to inform/engage the public on the benefits and risks of SMRs that may be sited in their community.
Staffing issues: The ICRP recently highlighted in its “Vancouver call for action” a need to strengthen expertise in radiological protection worldwide (Rühm et al., 2023). Concerns are growing that there is a shortage in investment in training and education in radiological protection, added to the issue that there is a diminishing number of persons available largely due to age-related factors. To support wide-spread SMR development and deployment, it may be challenging to ensure that qualified radiological protection personnel are available for safe operation of a facility, especially for SMRs located in remote locations or for multiple SMRs at one site. There will also need to be enough RP specialists available 24/7 for managing abnormal conditions and emergencies, and it must be ensured that personnel have knowledge, training, and experience in RP issues specific to the particular design. Addressing this challenge could greatly benefit workforce management for SMRs. Guidance may be needed to define staffing requirements for different technologies under different operational states and exposure scenarios; necessary training and minimum qualifications for facility staff; and recommendations for sustainable training programmes to increase the number of radiological protection professionals available.
Lack of operating experience (OPEX): Developing and deploying novel technologies means that there is minimal pre-existing experience of how the technology will perform throughout its life cycle. Although some knowledge can be drawn from existing large reactors and other industries, the lack of specific operating experience (OPEX) in SMRs raises a number of RP-related concerns. OPEX informs best practice, such as managing radiological protection issues related to the handling of fuel defects or proper disposal of waste and contaminants. OPEX also informs emergency preparedness and could be useful to address automation challenges. A lack of OPEX also means that applicants/vendors will need to carry additional research and collect evidence from other sources to demonstrate that they meet regulatory requirements. This, in turn, may make it difficult for regulators to ensure compliance with existing requirements without the insights that OPEX provides to review technical analyses. Addressing this challenge could facilitate the rapid enhancement of adiological protection practices related to new nuclear technologies and aid regulatory decision making. There would be the possibility of developing regulatory guidance, understanding the appropriateness of software modelling, and improving the sharing of OPEX, for example by creating a database for sharing knowledge/OPEX.
Emergency preparedness and response (EPR): EPR for nuclear facilities follows a graded approach based on the assessment of the potential hazards and consequences of an accident (considering the timing, types and amounts of radionuclides and exposure pathways of concern). SMRs are expected to have smaller source terms than traditional reactors and enhanced safety features to prevent or mitigate a potential radiological release. As such, the resources and capabilities needed to ensure an effective response and the types of protective action strategies needed will depend on the facility. Educational programmes for emergency managers, government officials, and the public are necessary to ensure appropriate and proportionate EPR arrangements for SMRs. Engaging with local communities will enhance public health and safety of surrounding communities, strengthen communication and help build trust with SMR operators and national and local authorities.
Further efforts are needed to develop evidence-based approaches to EPR for SMRs. This includes guidance on technology-specific protection strategies, considerations on the use of all-hazards response capabilities, and considerations on the size of an Emergency Planning Zone (EPZ) required for response planning. Appropriate and proportionate planning for SMRs emergency response will be beneficial in terms of cost-savings for communities and operators without compromising environmental and public health and safety. Addressing the SMR EPR issue with adequate resources, regulations, procedures, and capabilities should also include the development and promotion of an appropriate safety culture for radiological and nuclear emergencies by educating emergency managers, public officials, communication specialists and the public about the risks and benefits of SMRs and providing the information needed to make risk-informed protective action decisions.
Public risk perception and risk communication: Risk perception is mainly determined by trust, familiarity and knowledge of the issue, and the perceived benefits of action. It is influenced by effective risk communication, active engagement of the affected community and the strength of relationships. Challenges associated with public risk perception include differences in risk perception between experts and members of the public, lack of community and stakeholder engagement, socially divisive policy decisions, and differences in community concerns. Without appropriate dialogue between concerned parties, stakeholders will not be empowered to make informed decisions. It will be necessary to ensure that resources are available for public education and that a risk communication strategy is in place that incorporates a holistic view of public health and protection of the local environment into decision-making. The benefits of exploring the challenges associated with risk perception and communication will lead to a better understanding of the technology, strengthening of public trust and an appreciation of how regulation and operation interact in risk governance with relationships between diverse stakeholders. Existing guidance on effective communication strategies, public education, and improved community engagement leading to a better trust-building process could be adapted for SMRs.
The Task Force recognised that many of the above challenges are interrelated, and that there is considerable overlap between topics. The Task Force also recognised that radiological protection is only one of the issues to be considered under each of the challenges, and that they will also need to be addressed for other disciplines. For example, a lack of operational experience (OPEX) will also be a key consideration of nuclear safety, radioactive waste management, nuclear liabilities etc. associated with the development and deployment of new nuclear technologies.
The following matrix has been prepared by the Task Force to illustrate the cross-cutting nature of the challenges related to radiological protection. The matrix should be read by column. If the specific challenge affects another challenge, it is coloured yellow. If the specific challenge is affected by another challenge, it is coloured blue. If a column has more parts in yellow than in blue, then the challenge can be seen as having a tendency to be cross-cutting.
The Task Force prioritised the challenges in terms of importance from a radiological protection point of view, taking into consideration the specific and cross-cutting nature of the challenges. The importance of a specific challenge was largely based on expert elicitation considering many aspects, including safety relevance, timeliness, necessity, difficulty, and technological maturity of SMR designs. The Task Force recognises that prioritisation based on these factors may vary depending on areas of expertise and country-specific circumstances, among other factors. Therefore, rather than providing a quantitative ranking, the challenges were categorised as either ‘highly important’ or ‘important for further consideration. The prioritisation of the challenges will be used to inform the next phase of the Task Force’s work plan and to make recommendations to the CRPPH in terms of the areas to be targeted for in-depth review.
Highly important challenges:
Important challenges:
The prioritisation of addressing the challenges will vary depending upon factors beyond those the Task Force considered. Such factors, which are likely to be country-specific include: What SMR technology is being adopted? To what extent has the technology been developed? and What are the prevailing circumstances within a country (such as regulatory readiness, grid capacity, domestic or imported use of SMRs to be built, and prior experience with nuclear facilities)?
Many discussions on SMRs are underway at the NEA and internationally. In 2023-2024, the Task Force will work to identify where the radiological protection challenges can be integrated into existing mechanisms and where they are specific to the CRPPH by communicating with other divisions and committees of NEA and international organisations.
[1] In this context, ‘challenge’ refers to the Radiological Protection issues that national governments, regulators, industry, and other key stakeholders, such as the local community, could experience with the deployment of new nuclear technologies. Such challenges need to be addressed at the pre-operational phase to reduce the potential impacts and maximise opportunities for improvements.
NEA secretariat: kazuhiko.hiruta@oecd-nea.org
