Office for Nuclear Regulation

Our specialists

We have a range of specialists at ONR to ensure we have the skills and expertise to regulate. Our many highly qualified inspectors provide their specialist expertise to help us make our regulatory decisions.  They provide advice and guidance on their specialisms to the other divisions and to our Chief Nuclear Inspector. We also undertake research to inform our regulatory decisions. Read more about the research we conduct and why.

Electrical and Control and instrumentation specialism

Electrical, control and instrumentation equipment plays a key role in maintaining the safety of nuclear sites, and ensuring their continued efficient operation.

Inadequate design, maintenance, or use of these systems has the potential to affect nuclear safety at these sites.

Inspectors in our Electrical, Control and Instrumentation specialism are chartered engineers that have a wide range of nuclear and non-nuclear experience, both within the UK and internationally. They engage proactively with stakeholders to promote good practice and make evidence-based decisions to promote nuclear site safety.  

Inspectors from the specialism engage with nuclear site licensees to confirm that the risks associated with electrical, and control and instrumentation equipment are being properly managed, and if necessary, take action to ensure this, through the following:

  • Site inspections and targeted interventions on existing plant;
  • Assessment of proposed plant modifications;
  • Periodic safety assessments; and
  • Assessment of new nuclear designs.

Our specialist inspectors also recognise the importance of innovation in bringing about improvements to safety by:

  • Directing research both independently and in conjunction with licensees;
  • Stimulating cross industry working through a wide range of fora;
  • Encouraging industry development of new techniques and approaches; and
  • Participating in international fora to develop standards and guidance.

Our specialist inspectors also work collaboratively with other disciplines to develop an understanding of complex designs and promoting appropriate use of a range of technologies to achieve adequate levels of safety.

Chemistry and Chemical Engineering specialism

Inspectors in our Chemistry and Chemical Engineering specialism assess dutyholders’ safety cases and carry out inspections of nuclear sites across the entire nuclear fuel cycle, to ensure they meet our regulatory expectations.

Our inspectors in this specialism specifically examine site equipment and arrangements for maintaining confinement, cooling and control of radioactive substances and nuclear matter.

We do this by performing assessments and inspections related to chemical and thermal stability. This is to ensure all aspects covering radiological and non-radiological (i.e. combustible gases etc.) hazards and risks are appropriately considered, understood and safely controlled by the licensee.

We also examine whether dutyholders have appropriately identified potential fault and accident conditions at sites and have put in place suitable safety measures, limits and conditions to protect the workforce and members of the public.

Civil Engineering and External Hazards specialism

The Civil Engineering and External Hazards (CEEH) Specialism consists of a team of engineers and scientists who consider a range of safety and security features on UK nuclear sites and the challenges they will need to withstand throughout their operational life.

Civil engineering features often provide the most fundamental safety function on nuclear sites, including shielding from radiation and containment/confinement of nuclear materials. Most of the passive security preventing access to and protecting nuclear materials are also provided by civil engineering features. Civil structures are usually the first elements with a safety and security function to be created on a new nuclear site and the last to be removed at the end of a facility’s life.

Our specialist civil engineering inspectors consider the design, construction, operation, maintenance and decommissioning of these features at nuclear sites. Our inspectors seek evidence that these features will provide safety and security functions with very high reliability.

Some of the greatest potential challenges to nuclear safety and security are created by external hazards, which are defined as those hazards (natural or man-made) which originate externally from the site. This includes events such as earthquakes, flooding, storms and aircraft crash, many of which have the potential to adversely affect all safety and security features on a nuclear site and beyond the site boundary at the same time.

Our external hazards inspectors consider the range and severity of events that sites have been designed to safely and securely withstand. Our inspectors expect the industry to consider extreme events, far beyond those commonly experienced in the UK, together with combinations of events which could undermine safety or security at nuclear sites.

Climate change effects are also taken into account by our inspectors, with a range of climate change projections considered when making judgements on the safety of nuclear sites.

Cyber Security and Information Assurance specialism

Effective cyber security is increasingly important as modern technology and interconnected devices become a fundamental part of everyday life. It’s vital to protect the devices and services we access online and at work from harm.

Our Cyber Security and Information specialism is responsible for ensuring the civil nuclear sector protects the sensitive nuclear information it holds.

This sensitive nuclear information includes details about activities on nuclear sites which needs to be protected in the interests of national security - information that is of interest to those who may seek to harm the UK’s national interests. It can also be information that may be of use for the proliferation of weapons and needs to be tightly controlled.

Our specialist inspectors are responsible for ensuring the civil nuclear sector protects industrial processes from cyber-attack. The industrial sectors, including nuclear, have become more interconnected. This connectivity brings benefits, but it also presents additional risks to the safe operation of nuclear sites from those with malicious intent.

The specialism is a diverse mix of highly experienced cyber security professionals, apprentices and graduates, with backgrounds in a range of disciplines.

This breadth and depth of experience in the specialism, along with our strategic partnerships across government, intelligence agencies, industry and academia enables us to ensure that the civil nuclear sector adequately protects sensitive nuclear information and industrial systems against cyber-attack.

Fault Analysis specialism

Inspectors in our Fault Analysis specialism assess the fault analysis work undertaken by dutyholders.

The dutyholders’ fault analysis identifies all the potential events that can affect the safety of their facility, determines their potential consequences, and identifies suitable and sufficient means to prevent, protect or mitigate against them.

Our fault analysis specialism includes the following sub-specialisms:

  • Fault Studies – these inspectors consider the analysis of physical processes to predict how potential faults progress and determine how the identified safety measures will respond.
  • Fuel and Core – these inspectors consider the safety analysis of the nuclear fuel used within a reactor core; inadequate performance could lead to a reactor which is difficult to control or susceptible to overheating.
  • Probabilistic Safety Analysis – these inspectors consider the development and use of probabilistic models by dutyholders to justify the safety of a facility and to risk inform its design and operation.   
Our inspectors’ work is vital to ensuring safety at nuclear sites as it is essential that the dutyholder has correctly determined the safety performance of nuclear fuel. They must also understand how potential faults progress and control the risks from their operations.

Human and Organisational Capability specialism

Inspectors in our Human and Organisational Capability (HOC) specialism analyse the important role played by people and processes at nuclear sites.  

Nuclear sites are often analysed through the lens of the ‘three Ps’ - People, Processes and Plant. Our HOC inspectors focus on the way people working at nuclear sites interact with each other and the processes they follow.

This involves looking at how people working at nuclear sites respond to technical and managerial systems, culture and the work environment. The specialism does this for all UK nuclear sites for the complete life cycle of the plant.

Our HOC specialist inspectors are divided into the following five sub-specialisms:

  • Leadership and Management;
  • Human Factors;
  • Supply Chain;
  • Quality; and
  • Licensing.
Through targeted engagement with dutyholders these inspectors observe the role people and processes play, both positively and negatively, on the safe operations of nuclear sites to ensure they are meeting the required standards.

Mechanical Engineering specialism

Our Mechanical Engineering specialists assess and inspect the safety of mechanical equipment, seeking proportionate improvements where safety shortfalls are identified.

Our remit includes:

  • ventilation and containment systems
  • glove boxes
  • lifting equipment
  • fuel and radioactive waste handling equipment
  • power reactor mechanical systems
  • nuclear chemical and process plant
  • heat transfer equipment and design considerations
  • pressure systems
  • asset management and maintenance
  • transport containers
  • engineering design processes
  • safety case production and assessment

Our specialists have a wide range of nuclear and non-nuclear experience, both within the UK and internationally. The systems we assess are often complex and encompass elements that are outside of mechanical engineering. In these cases we work collaboratively with other ONR specialist disciplines. This collaborative approach enables us to promote safe application of a range of technologies.

We also collaborate with external stakeholders to improve safety across the industry. This is achieved by:

  • directing research both independently and in conjunction with licensees
  • stimulating industry to develop new techniques and approaches
  • participating in the development of international standards

Nuclear Internal Hazards and Site Safety specialism

Inspectors in our Nuclear Internal Hazards and Site Safety specialism ensure safety systems, structures and components at nuclear sites across the UK are safe and that risks are being appropriately managed.

Ensuring that systems, structures and components are safe is vital to protect workers and the public against radiation releases and other hazards to health, safety and welfare.  

The specialism consists of three disciplines regulating nuclear internal hazards, life fire safety and nuclear site health and safety (including major accident hazards) on all ONR regulated nuclear sites.

Nuclear internal hazards are classed as hazards that present a significant threat to safety at a nuclear site. These hazards come from within the nuclear site’s structures, systems and components which are controlled by the licensee. They include fire safety, explosion, internal flooding, steam release, rotating machinery and toxic or corrosive gas releases amongst others.  

Regular inspections are undertaken by the specialism to ensure the licensee has adequate (i.e. meets the required standard) arrangements in place to protect engineering systems and equipment from damage. These measures safeguard the public and workers against the possibility of a release of radiation.

The specialism also considers nuclear site health and safety - conventional health and safety - at all ONR regulated nuclear sites. It considers the management of risks arising from hazards to workers and members of the public from all work activities on these nuclear sites.

Many of the health and safety areas regulated at nuclear sites by the specialism also have a direct impact on nuclear safety. Priority areas for our regulatory focus include:

  • construction operations (including new nuclear build and decommissioning);
  • work at height;
  • hazardous substances (including asbestos and legionella);
  • work in confined spaces;
  • electricity;
  • machinery safety;
  • workplace transport; and
  • exposure to noise and vibration.

Nuclear Liabilities Regulation specialism

Our Nuclear Liabilities Regulation (NLR) specialism is made up of inspectors from scientific and engineering backgrounds.

NLR inspectors carry out a range of inspection activities at nuclear sites across the UK to ensure the effective regulation of:

  • The accumulation, processing, storage, and disposal of radioactive waste;
  • The management of radioactive materials spent nuclear fuel, and other nuclear materials;
  • The decommissioning of nuclear sites;
  • The management of radioactively contaminated land on nuclear sites; and
  • The clean-up of nuclear sites to achieve a site end state suitable for delicensing and release from regulatory control.

NLR inspectors assess documentation including safety submissions about the above activities. These assessment inspection activities support the regulation of continued safe operation of nuclear sites, the remediation of legacy wastes and facilities and the construction of new facilities.

The specialism also delivers ONR’s statutory responsibility to ensure that the environmental impacts of decommissioning projects are managed appropriately, issuing consents when appropriate.

The activities the specialism regulates are often undertaken over long timescales. For example, the degradation of facilities and stored wastes, and the requirement to avoid the creation of unnecessary legacy wastes and facilities.

The specialism works closely with the other environment agencies on areas of joint interest, including drafting and publishing joint guidance to support compliance with legislation. An important area of joint working is related to the disposal of radioactive waste in a Geological Disposal Facility.

NLR inspectors also engage with industry on research and development for managing nuclear liabilities.

Our NLR inspectors undertake strategic work with national and international bodies, supporting government meet its obligations in the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management.

Protective Security specialism

The terrorist attacks in the United States of America on 11 September 2001 changed the world. We entered a new period of international terrorism which requires a global multilateral response to combat.

The Convention on the Physical Protection of Nuclear Materials was amended as a response to this event. The amendment expanded the scope of the convention to cover the physical protection of nuclear sites and material used for peaceful purposes in domestic use, storage and transport.

The UK is signed up to this convention, which places legally binding obligations on the UK regarding civil nuclear security. Our Protective Security specialism plays an integral part in ensuring those obligations are fulfilled through its regulation of the nuclear industry.

Our nuclear security regulation focuses on protecting the public from a radiological event caused by the theft or sabotage of nuclear materials, associated facilities (such as structures, systems and components important to nuclear safety), and transport of these materials.

We do this by thoroughly assessing and testing the nuclear industry’s security arrangements to ensure efficacy against a range of terrorist threats. We also conduct regular inspections to assure they are compliant with these arrangements as required by the Nuclear Industries Security Regulations (NISR) 2003.

We are also the workforce vetting authority for the civil nuclear industry of approximately 63,000 personnel - making us the third largest vetting authority in the UK. As well as overseeing pre-employment screening and national security vetting, we are also responsible for ensuring compliance with ongoing personnel security (known as aftercare) arrangements. This includes employer policies that promote an effective personnel security culture.

Together, vetting and aftercare are designed to assure the initial and ongoing honesty, integrity and trustworthiness of the workforce. Pre-employment screening checks are delivered by the respective licensed site.

Our Protective Security specialism reviews employer policies on the existence of suitable employee support services for those experiencing difficulties, for example, with finance or stress; drug and alcohol testing arrangements; social media etc. This helps to identify and mitigate the potential for individuals to exercise poor judgement or be susceptible to coercion, blackmail, or becoming an insider threat.

These measures are important to provide confidence that the workforce within the industry - who may have access to certain materials or safety-critical systems - do not deliberately or carelessly take actions which could potentially cause harmful radiological consequences.

Radiation Protection and Criticality specialism

Our Radiation Protection and Criticality (RP&C) specialism supports regulatory activity across ONR to ensure that workers and the public are protected from ionising radiation, on and around nuclear sites and via the transport of radioactive materials. This includes both normal operation and emergency situations.

We carry out assessments and inspections of civil, defence and transport dutyholders, primarily to measure compliance with the Ionising Radiations Regulations 2017 (IRR17) and Radiation (Emergency Preparedness and Public Information) Regulations 2019 (REPPIR19). Our inspectors ensure new power stations are designed in a way that restricts radiation exposure, and our experts ensure dutyholders’ arrangements remain safe with respect to criticality.

Our experts in personal protective equipment, shielding, emergency preparedness and radiation consequences work to support ONR’s activities. This includes managing ONR’s dosimetry needs, and we have a dedicated Radiation Protection Adviser (RPA) who can advise any ONR employee on their own radiation protection safety.

RP&C is also responsible for a number of ONR’s statutory duties:

As well as working within the UK to promote the development and adoption of relevant good practice, our inspectors attend and support international fora to positively influence global standards and best practice in all aspects of radiation protection, including the IAEA’s Radiation Safety Standards (RASSC) and Emergency Preparedness and Response Standards (EPReSC) Committees, the Heads of European Radiation protection Competent Authorities association (HERCA) and the Nuclear Energy Agency (NEA).

Safeguards specialism

Nuclear safeguards are measures to verify that countries comply with international obligations not to use nuclear materials (uranium, plutonium and thorium) from civil nuclear programmes for non-peaceful purposes.

ONR is the UK’s safeguards regulator, and forms part of the UK State System of Accounting for, and Control of, Nuclear Materials.

The inspectors within our Safeguards specialism are responsible for the operation of the domestic nuclear safeguards regime. This involves assessing and inspecting dutyholder arrangements, procedures and records relating to nuclear material accountancy.

Inspectors in this specialism also assess and inspect dutyholders safeguards-relevant design information of nuclear facilities, and accountancy and control plans to regulate compliance against Nuclear Safeguards (EU Exit) Regulations 2019.

Our inspectors in this specialism are also responsible for ensuring that we enable the UK to meet its international safeguards obligations with the International Atomic Energy Agency (IAEA) and other international partners.

The Safeguards specialism provides expert regulatory advice and guidance to government and is represented on a number of international forums and working groups. This includes the European Safeguards Research and Development Association, the Institute of Nuclear Materials Management and IAEA consultancy groups.

The specialism covers the following issues at these international forums:

  • Safeguards by design;
  • Implementation of safeguards;
  • Training and knowledge management for safeguards;
  • Development of an international safeguards practitioners certification;
  • Material balance evaluation; and
  • Safeguards considerations for geological disposal.

Structural Integrity specialism

Inspectors in our Structural Integrity specialism ensure that the integrity of key components of nuclear reactors meets the required standards to safely operate.  

These components include reactor pressure vessels, nuclear pipework, boiler tubes, storage tanks, structures internal to the reactor and the graphite core in gas cooled reactors.  

They carry out regular inspections and assessments of safety cases to ensure the parts listed above are being appropriately looked after by the operators. This is done for the design, manufacturing, operation and decommissioning phases of all nuclear sites to ensure worker and public safety.

Our Structural Integrity specialism inspectors are highly skilled and experienced. They understand how the inter-relationship between stresses, materials, defects and degradation mechanisms can affect the components of the plant listed above. They then carry out inspections to ensure the nuclear site is safe to operate.  

Our specialist inspectors make important regulatory decisions on plant integrity issues. These include the end-of-life condition of the gas-cooled reactor, graphite core of reactors and the demonstration of reactor pressure vessel reactor integrity. Our specialist inspectors do this throughout a reactor’s life cycle taking account of any degradation that occurs over time.