ONR has established its Safety Assessment Principles (SAPs) which apply to the assessment by ONR specialist inspectors of safety cases for nuclear facilities that may be operated by potential licensees, existing licensees, or other duty-holders. The Security Assessment Principles (SyAPs) apply to the assessment of security plans which include site security plans and transport security statements. The principles presented in the SAPs and SyAPs are supported by a suite of guides to further assist ONR's inspectors in their technical assessment work in support of making regulatory judgements and decisions.
This page contains Technical Assessment Guides (TAGs). These primarily provide guidance to ONR inspectors on the interpretation and application of the SAPs and SyAPs. However, some also contain guidance relevant to principles underlining the enforcement of licence condition compliance, which supplements the Technical Inspection Guides. Thus the TAGs have relevance to all inspectors within ONR, regardless of function. The TAGs also provide information to licensees and dutyholders regarding ONR's expectations of the nature and content of relevant technical elements of safety cases and security plans.
The TAGs provide guidance in particular technical areas, and they are to be used at the discretion of inspectors.
Responsibility for the maintenance of TAGs is shared between ONR's Professional Leads for individual technical areas and the Regulatory and Technical Standards sub programme within ONR's Technical Division.
The guides available below are the latest issues. As revised versions are produced they will replace the older versions.
Those civil nuclear industry dutyholders who need a document containing sensitive nuclear information, should contact cns.support@onr.gov.uk
Should you have any feedback on our guidance, please email contact@onr.gov.uk
NOTE: ONR operates a robust governance process for the review, and update as appropriate, of our regulatory standards and guidance. As a regulator, we are involved in the management of a range of relevant international standards and guidance, including International Atomic Energy Agency (IAEA) Safety Standards and Security Guidance, and the Western European Nuclear Regulators Association (WENRA) Safety Reference Levels (SRL). We ensure that all relevant expectations are reflected in the appropriate ONR internal guidance once those international documents are formally published.
In some cases, our guidance documents are updated in advance of the stated formal review date (because of a significant change in relevant good practice, updated international standards or guidance, or amendments to UK legislation). In other instances, where we have judged that there have been no changes that would materially affect our guidance and it therefore remains appropriate to continue use of the existing version, then the formal review date may be passed.
Where published documents have passed their formal review date, we confirm that there are no significant changes in relevant good practice, modifications to international standards or guidance, or amendments to UK legislation that might significantly alter the content of that internal guidance. Consequently, this has no impact on our robust regulation and our inspectors continue to hold the industry account against the high standards required under UK law.
Any documents that have passed their review date remain subject to our review processes, as stated on our website, and the review dates will be updated in due course.
| Document ID | Review date | Title |
|---|---|---|
| Nuclear safety | ||
| NS-TAST-GD-002 (Issue 8.1) | July 2028 | Radiation Shielding |
| NS-TAST-GD-003 (Issue 9.2) | September 2024 | Safety Systems |
| NS-TAST-GD-004 (Issue 8) | April 2028 | Fundamental Principles of safety assessment |
| NS-TAST-GD-005 (Issue 11.2) | December 2023 | Guidance on the Demonstration of ALARP (As Low As Reasonably Practicable) |
| NS-TAST-GD-006 (Issue 5.1) | October 2025 | Design Basis Analysis |
| NS-TAST-GD-007 (Issue 5.1) | August 2027 | Severe Accident Analysis |
| NS-TAST-GD-009 (Issue 7) | November 2028 | Examination, Inspection, Maintenance and Testing of Items Important to Safety |
| NS-TAST-GD-010 (Issue 7.1) | December 2024 | Early Initiation of Safety Systems |
| NS-TAST-GD-011 (Issue 2) | Currently under review | The single failure criterion |
| NS-TAST-GD-013 (Issue 9) | October 2028 | External hazards |
| NS-TAST-GD-014 (Issue 7.1) | October 2026 | Internal Hazards |
| NS-TAST-GD-015 (Issue 3.1) | May 2025 | Electromagnetic Interference |
| NS-TAST-GD-016 (Issue 7) | April 2025 | Integrity of Metal Structures, Systems and Components |
| NS-TAST-GD-017 (Issue 4.1) | November 2025 | Civil Engineering |
| NS-TAST-GD-018 (Issue 8) | October 2023 | Criticality Warning Systems |
| NS-TAST-GD-019 (Issue 5.1) | April 2024 | Essential Services |
| NS-TAST-GD-020 (Issue 6.1) | May 2025 | Civil Engineering Containments for Reactor Plants |
| NS-TAST-GD-021 (Issue 6) | June 2024 | Containment: Chemical Plants |
| NS-TAST-GD-022 (Issue 8.1) | June 2027 | Ventilation |
| NS-TAST-GD-023 (Issue 6.1) | August 2024 | Control of Processes Involving Nuclear Matter (SAP - ENM. 1 to 8) |
| NS-TAST-GD-024 (Issue 7.2) | December 2023 | Management of Radioactive Material and Radioactive Waste on Nuclear Licensed Sites |
| NS-TAST-GD-026 (Issue 5.2) | September 2023 | Decommissioning |
| NS-TAST-GD-027 (Issue 7) | December 2027 | Training and assuring personnel competence |
| NS-TAST-GD-028 (Issue 6.1) | October 2024 | Control and Instrumentation Aspects of Nuclear Plant Commissioning |
| NS-TAST-GD-029 (Issue 5) | November 2023 | Graphite reactor cores |
| NS-TAST-GD-030 (Issue 7) | April 2024 | Probabilistic Safety Analysis |
| NS-TAST-GD-031 (Issue 7) | May 2028 | Safety related Systems and Instrumentation |
| NS-TAST-GD-033 (Issue 7.1) | February 2024 | Duty Holder Management of Records |
| NS-TAST-GD-035 (Issue 7) | March 2028 | The Limits and Conditions for Nuclear Safety (Operating Rules) |
| NS-TAST-GD-036 (Issue 6) | October 2028 | Redundancy, Diversity, Segregation and Layout of Structures, Systems and Components |
| NS-TAST-GD-038 (Issue 10) | November 2027 | Radiological Protection |
| NS-TAST-GD-041 (Issue 7) | January 2024 | Criticality Safety |
| NS-TAST-GD-042 (Issue 5.1) | September 2024 | Validation of Computer Codes and Calculation Methods |
| NS-TAST-GD-043 (Issue 6) | July 2024 | Radiological Analysis - Normal Operation |
| NS-TAST-GD-045 (Issue 6) | April 2024 | Radiological analysis - Fault conditions |
| NS-TAST-GD-046 (Issue 6) | October 2023 | Computer Based Safety Systems |
| NS-TAST-GD-048 (Issue 7) | July 2028 | Organisational Change |
| NS-TAST-GD-049 (Issue 7.1) | July 2024 | Licensee Core Safety and Intelligent Customer Capabilities |
| NS-TAST-GD-050 (Issue 8.1) | October 2025 | Periodic Safety Reviews (PSRs) [NS-TAST-GD-050] |
| NS-TAST-GD-051 (Issue 7.1) | December 2024 | The purpose, scope and content of safety cases |
| NS-TAST-GD-056 (Issue 7.1) | October 2028 | Nuclear Lifting Operations |
| NS-TAST-GD-057 (Issue 7) | May 2027 | Design Safety Assurance |
| NS-TAST-GD-058 (Issue 5) | March 2026 | Human Factors Integration (HFI) |
| NS-TAST-GD-059 (Issue 5.2) | December 2024 | Human Machine Interface (HMI) |
| NS-TAST-GD-060 (Issue 5) | December 2027 | Procedure Design and Administrative Controls |
| NS-TAST-GD-061 (Issue 5) | June 2028 | Staffing Levels and Task Organisation |
| NS-TAST-GD-062 (Issue 4.2) | October 2025 | Workplaces and Work Environment |
| NS-TAST-GD-063 (Issue 6) | December 2027 | Human Reliability Analysis |
| NS-TAST-GD-064 (Issue 5) | May 2028 | Allocation of Function between Human and Engineered Systems |
| NS-TAST-GD-065 (Issue 5) | July 2028 | Function and Content of the Nuclear Baseline |
| NS-TAST-GD-067 (Issue 3.2) | June 2027 | Pressure Systems Safety |
| NS-TAST-GD-072 (Issue 4.1) | July 2027 | Function and Content of a Safety Management Prospectus |
| NS-TAST-GD-075 (Issue 3.1) | September 2025 | Safety of Nuclear Fuel in Power Reactors |
| NS-TAST-GD-077 (Issue 6.2) | July 2024 | Supply Chain Management Arrangements for the Procurement of Nuclear Safety Related Items or Services |
| NS-TAST-GD-079 (Issue 6.1) | July 2024 | Licensee Design Authority Capability |
| NS-TAST-GD-080 (Issue 5) | January 2028 | Nuclear Safety Advice and Independent Challenge |
| NS-TAST-GD-081 (Issue 4.1) | June 2024 | Safety Aspects Specific to Storage of Spent Nuclear Fuel |
| NS-TAST-GD-083 (Issue 2.2) | November 2024 | Land Quality Management |
| NS-TAST-GD-087 (Issue 2.1) | July 2027 | Control of Property Transactions on Licensed Sites |
| NS-TAST-GD-088 (Issue 3) | January 2024 | Chemistry of Operating Civil Nuclear Reactors |
| NS-TAST-GD-089 (Issue 1.1) | February 2026 | Chemistry Assessment |
| NS-TAST-GD-093 (Issue 2) | Document replaced - TD-HOC-GD-002 - Leadership and Management for Safety Reviews | Guidance for undertaking Leadership and Management for Safety Reviews |
| NS-TAST-GD-094 (Issue 2) | July 2024 | Categorisation of Safety Functions and Classification of Structures and Components |
| NS-TAST-GD-096 (Issue 1.2) | November 2027 | Guidance on Mechanics of Assessment |
| NS-TAST-GD-097 (Issue 2) | April 2025 | Criticality Safety Assessment of Transport Packages |
| NS-TAST-GD-098 (Issue 2.1) | October 2024 | Asset Management |
| NS-TAST-GD-099 (Issue 2.2) | August 2027 | Transport Engineering Assessment |
| NS-TAST-GD-100 (Issue 2) | October 2024 | Shielding and Dose Rate Safety Assessment of Transport Packages |
| NS-TAST-GD-101 (Issue 1.3) | March 2028 | Geological Disposal |
| NS-TAST-GD-102 (Issue 2) | June 2028 | General Guidance for Mechanical Engineering Specialism Group |
| NS-TAST-GD-103 (Issue 1.1) | October 2023 | Emergency Power Generation |
| NS-TAST-GD-104 (Issue 1) | February 2025 | Corporate Governance for Safety |
| NS-TAST-GD-105 (Issue 1) | June 2028 | The Assessment of the Nuclear Reactors (Environmental Impact Assessment for Decommissioning) Regulations Submissions |
| NS-TAST-GD-107 (Issue 1.2) | April 2027 | Safety Leadership |
NS-TAST-GD-109 (Issue 1) |
February 2028 | Ageing and Degradation Management |
| Civil Nuclear Security | ||
| CNS-TAST-GD-1.1 (Issue 1) | March 2025 | Security Governance and Leadership |
| CNS-TAST-GD-1.2 (Issue 2.1) | April 2027 | Organisational Security Capability |
| CNS-TAST-GD-1.3 (Issue 1) | March 2025 | Security Decision Making |
| CNS-TAST-GD-1.4 (Issue 1) | March 2025 | Organisational Learning for Security |
| CNS-TAST-GD-1.5 (Issue 1) | March 2024 | Security Assurance Processes |
| CNS-TAST-GD-2.1 (Issue 2) | March 2025 | Maintenance of a Robust Security Culture |
| CNS-TAST-GD-3.1 (Issue 3.1) | April 2027 | Identification and Analysis of Security Tasks and Roles |
| CNS-TAST-GD-3.2 (Issue 3) | April 2027 | Sufficiency and Competence of Personnel Delivering Security |
| CNS-TAST-GD-3.3 (Issue 3) | April 2027 | |
| CNS-TAST-GD-3.4 (Issue 3) | April 2027 | Procedures and Administrative Controls |
| CNS-TAST-GD-4.1 (Issue 1) | March 2024 | Procurement and Intelligent Customer Capability |
| CNS-TAST-GD-4.2 (Issue 1) | March 2024 | Supplier Capability |
| CNS-TAST-GD-4.3 (Issue 1) | March 2024 | Oversight of Suppliers |
| CNS-TAST-GD-4.4 (Issue 1) | March 2024 | Commissioning |
| CNS-TAST-GD-5.1 (Issue 2) | March 2025 | Reliability and Resilience of the Security System |
| CNS-TAST-GD-5.2 (Issue 2) | March 2025 | Examination, Inspection, Maintenance and Testing of Physical Protection Systems |
| CNS-TAST-GD-5.3 (Issue 2) | March 2025 | Sustainability of Nuclear Security Arrangements |
| CNS-TAST-GD-6.1 (Issue 2) | March 2025 | Categorisation for Theft |
| CNS-TAST-GD-6.2 (Issue 2) | June 2025 | Categorisation for Sabotage |
| CNS-TAST-GD-6.4 (Issue 1.1) | April 2027 | Vulnerability Assessments |
| CNS-TAST-GD-6.5 (Issue 1.1) | April 2027 | Adjacent or Enclave Nuclear Premises |
| CNS-TAST-GD-6.6 (Issue 2) | March 2025 | Nuclear Construction Sites |
| CNS-TAST-GD-6.7 (Issue 2) | March 2025 | Class A Carriers – Transport Security Statements and Plans |
| CNS-TAST-GD-7.1 (Issue 2) | March 2026 | Effective Cyber and Information Risk Management |
| CNS-TAST-GD-7.2 (Issue 2.1) | March 2027 | Information Security |
| CNS-TAST-GD-7.4 (Issue 2) | April 2026 | Physical Protection of Information |
| CNSS-TAST-GD-7.5 (Issue 3) | March 2024 | Preparation for and Response to Cyber Security Events |
| CNS-TAST-GD-8.1 (Issue 1) | November 2024 | Cooperation of Departments with responsibility for delivering vetting and ongoing personnel security arrangements |
| CNS-TAST-GD-8.2 (Issue 1) | November 2024 | Pre-employment Screening and National Security Vetting |
| CNS-TAST-GD-8.3 (Issue 1) | November 2024 | Ongoing Personnel Security Aftercare |
| CNS-TAST-GD-9.1 (Issue 1) | March 2024 | CNC Response Force |
| CNS-TAST-GD-9.2 (Issue 1) | March 2024 | Local Police Forces |
| CNS-TAST-GD-9.3 (Issue 1) | March 2024 | Security Guard Services |
| CNS-TAST-GD-10.1 (Issue 2) | October 2024 | CT Measures EP&R Planning |
| CNS-TAST-GD-10.2 (Issue 2.1) | October 2024 | Testing and Exercising the Security Response |
| CNS-TAST-GD-10.3 (Issue 3) | March 2025 | Clarity of Command, Control and Communications Arrangements During and Post a Nuclear Security Event |
| CNSS-TAST-GD-11.1 (Issue 1.2) | May 2026 | Guidance on the Security Assessment of Generic New Nuclear Reactor Designs |
| CNS-TAST-GD-11.4.1 (Issue 1.1) | January 2028 | Secure by Design |
| CNS-TAST-GD-11.4.2 (Issue 1) | April 2027 | The Threat |
| CNS-TAST-GD-11.4.5 (Issue 1) | April 2027 | Functional Categorisation and Classification of Security Structures, Systems and Components |
| CNS-TAST-GD-11.4.6 (Issue 1.1) | April 2027 | Managing Changes to Security Standards, Procedures and Arrangements |
| Safeguards | ||
| SG-TAST-GD-001 (Issue 4) | January 2026 | Safeguards |
| SG-TAST-GD-002 (Issue 2) | January 2025 | Nuclear Material Accountancy |