Office for Nuclear Regulation

Permissioning inspection - Technical assessment guides

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.

Official sensitive

Those civil nuclear industry dutyholders who need a document containing sensitive nuclear information, should contact cns.support@onr.gov.uk

Feedback

Should you have any feedback on our guidance, please email contact@onr.gov.uk

Document ID Review date Title
Nuclear safety
NS-TAST-GD-002 (Rev 8) July 2023 Radiation Shielding
NS-TAST-GD-003 (Rev 9) October 2022 Safety Systems
NS-TAST-GD-004 (Rev 7) April 2023 Fundamental Principles
NS-TAST-GD-005 (Rev 11) March 2023 Guidance on the Demonstration of ALARP (As Low As Reasonably Practicable)
NS-TAST-GD-006 (Rev 5) October 2025 Design Basis Analysis
NS-TAST-GD-007 (Rev 4) September 2020 Severe Accident Analysis
NS-TAST-GD-009 (Rev 6) October 2023 Examination, Inspection, Maintenance and Testing of Items Important to Safety
NS-TAST-GD-010 (Rev 6) September 2021 Early initiation of safety systems
NS-TAST-GD-011 (Rev 2) Withdrawn pending review The single failure criterion
NS-TAST-GD-013 (Rev 8) October 2023 External hazards
NS-TAST-GD-014 (Rev 6) November 2024 Internal Hazards
NS-TAST-GD-015 (Rev 3) May 2025 Electromagnetic Interference
NS-TAST-GD-016 (Rev 7) April 2025 Integrity of Metal Structures, Systems and Components
NS-TAST-GD-017 (Rev 4) November 2025 Civil Engineering
NS-TAST-GD-018 (Rev 8) October 2023 Criticality Warning Systems
NS-TAST-GD-019 (Rev 5) April 2024 Essential Services
NS-TAST-GD-020 (Rev 6) May 2025 Civil Engineering Containments for Reactor Plants
NS-TAST-GD-021 (Rev 6) June 2024 Containment: Chemical Plants
NS-TAST-GD-022 (Rev 7) December 2024 Ventilation
NS-TAST-GD-023 (Rev 6) August 2024 Control of Processes Involving Nuclear Matter (SAP - ENM. 1 to 8)
NS-TAST-GD-024 (Rev 7) June 2023 Management of Radioactive Material and Radioactive Waste on Nuclear Licensed Sites
NS-TAST-GD-026 (Rev 5) September 2022 Decommissioning
NS-TAST-GD-027 (Rev 6) December 2021 Training and assuring personnel competence
NS-TAST-GD-028 (Rev 6) October 2024 Control and Instrumentation Aspects of Nuclear Plant Commissioning
NS-TAST-GD-029 (Rev 5) November 2023 Graphite reactor cores
NS-TAST-GD-030 (Rev 7) April 2024 Probabilistic Safety Analysis
NS-TAST-GD-031 (Rev 6) April 2023 Safety related Systems and Instrumentation
NS-TAST-GD-033 (Rev 7) February 2024 Duty Holder Management of Records
NS-TAST-GD-035 (Rev 6) December 2022 The Limits and Conditions for Nuclear Safety (Operating Rules)
NS-TAST-GD-036 (Rev 5) February 2021 Diversity, redundancy, segregation and layout of mechanical plant
NS-TAST-GD-038 (Rev 9) November 2022 Radiological Protection
NS-TAST-GD-041 (Rev 7) January 2024 Criticality Safety
NS-TAST-GD-042 (Rev 5) September 2023 Validation of Computer Codes and Calculation Methods
NS-TAST-GD-043 (Rev 6) July 2024 Radiological Analysis - Normal Operation
NS-TAST-GD-045 (Rev 6) April 2024 Radiological analysis - Fault conditions
NS-TAST-GD-046 (Rev 6) October 2023 Computer Based Safety Systems
NS-TAST-GD-048 (Rev 6) July 2023 Organisational Change
NS-TAST-GD-049 (Rev 7) November 2023 Licensee Core Safety and Intelligent Customer Capabilities
NS-TAST-GD-050 (Rev 8) October 2025 Periodic Safety Reviews (PSRs) [NS-TAST-GD-050]
NS-TAST-GD-051 (Rev 7) December 2024 The purpose, scope and content of safety cases
NS-TAST-GD-056 (Rev 7) February 2023 Nuclear Lifting Operations
NS-TAST-GD-057 (Rev 6) October 2022 Design Safety Assurance
NS-TAST-GD-058 (Rev 4) March 2023 Human Factors Integration
NS-TAST-GD-059 (Rev 5) December 2022 Human Machine Interface
NS-TAST-GD-060 (Rev 4) March 2022 Procedure Design and Administrative Controls
NS-TAST-GD-061 (Rev 4) March 2022 Staffing levels and task organisation
NS-TAST-GD-062 (Rev 4) October 2025 Workplaces and Work Environment
NS-TAST-GD-063 (Rev 5) July 2022 Human Reliability Analysis
NS-TAST-GD-064 (Rev 4) December 2021 Allocation of Function between Human and Engineered Systems
NS-TAST-GD-065 (Rev 4) January 2023 Function and Content of the Nuclear Baseline
NS-TAST-GD-067 (Rev 2) February 2022 Pressure Systems
NS-TAST-GD-072 (Rev 4) July 2022 Function and Content of a Safety Management Prospectus
NS-TAST-GD-075 (Rev 3) September 2025 Safety of Nuclear Fuel in Power Reactors
NS-TAST-GD-077 (Rev 6) July 2024 Supply Chain Management Arrangements for the Procurement of Nuclear Safety Related Items or Services
NS-TAST-GD-079 (Rev 6) April 2024 Licensee Design Authority Capability
NS-TAST-GD-080 (Rev 4) January 2023 Challenge Culture, Independent Challenge Capability (including an Internal Regulation function) and the Provision of Nuclear Safety Advice
NS-TAST-GD-081 (Rev 4) June 2024 Safety Aspects Specific to Storage of Spent Nuclear Fuel
NS-TAST-GD-083 (Rev 2) November 2023 Land Quality Management
NS-TAST-GD-087 (Rev 2) June 2022 Control of Property Transactions on Licensed Sites
NS-TAST-GD-088 (Rev 3) January 2024 Chemistry of Operating Civil Nuclear Reactors
NS-TAST-GD-089 (Rev 1) February 2026

Chemistry Assessment
NS-TAST-GD-093 (Rev 2) Withdrawn pending review Guidance for undertaking Leadership and Management for Safety Reviews
NS-TAST-GD-094 (Rev 2) July 2024 Categorisation of Safety Functions and Classification of Structures and Components
NS-TAST-GD-096 (Rev 0) April 2023 Guidance on Mechanics of Assessment
NS-TAST-GD-097 (Rev 2) April 2025 Criticality Safety Assessment of Transport Packages
NS-TAST-GD-098 (Rev 2) October 2024 Asset Management
NS-TAST-GD-099 (Rev 1) June 2021 Transport Engineering Assessment
NS-TAST-GD-100 (Rev 2) October 2024 Shielding and Dose Rate Safety Assessment of Transport Packages
NS-TAST-GD-101 (Rev 1) January 2023 Geological Disposal
NS-TAST-GD-102 (Rev 1) June 2023 General Guidance for Mechanical Engineering Specialism Group
NS-TAST-GD-103  (Rev 1) October 2023 Emergency Power Generation
Civil Nuclear Security
CNS-TAST-GD-1.1 (Rev 1) March 2025Security Governance and Leadership
CNS-TAST-GD-1.2 (Rev 2) March 2022Organisational Security Capability
CNS-TAST-GD-1.3 (Rev 1) March 2025Security Decision Making
CNS-TAST-GD-1.4 (Rev 1) March 2025Organisational Learning for Security
CNS-TAST-GD-1.5 (Rev 1) March 2024Security Assurance Processes
CNS-TAST-GD-2.1 (Rev 1) March 2023Maintenance of a Robust Security Culture
CNS-TAST-GD-3.1 (Rev 2) March 2022Analysis of Security Roles & Associated Competencies
CNS-TAST-GD-3.2 (Rev 2) March 2022Identification of Learning Objectives and Training Needs
CNS-TAST-GD-3.3 (Rev 2) March 2022Measurement of Competence
CNS-TAST-GD-3.4 (Rev 2) March 2022Organisation of and Support to the Training Function
CNS-TAST-GD-4.1 (Rev 1) March 2024Procurement and Intelligent Customer Capability
CNS-TAST-GD-4.2 (Rev 1) March 2024Supplier Capability
CNS-TAST-GD-4.3 (Rev 1) March 2024Oversight of Suppliers
CNS-TAST-GD-4.4 (Rev 1) March 2024Commissioning
CNS-TAST-GD-5.1 (Rev 1) March 2023Reliability and Resilience
CNS-TAST-GD-5.2 (Rev 1) March 2023Examination, Inspection, Maintenance and Testing
CNS-TAST-GD-5.3 (Rev 1) March 2022Sustainability
CNS-TAST-GD-6.1 (Rev 1) April 2023Categorisation for Theft
CNS-TAST-GD-6.2 (Rev 1) March 2022 Categorisation for Sabotage
NS-TAST-GD-6.4 (Rev 1) March 2022Vulnerability Assessment
CNS-TAST-GD-6.5 (Rev 1) March 2022Adjacent or Enclave Nuclear Premises
CNS-TAST-GD-6.6 (Rev 1) March 2024 Nuclear Construction Sites
CNS-TAST-GD-6.7 (Rev 1) May 2023Class A Carriers – Transport Security Statements and Plans
CNS-TAST-GD-7.1 (Rev 1) March 2023Effective Cyber and Information Risk Management
CNS-TAST-GD-7.2 (Rev 1) March 2023Information Security
CNS-TAST-GD-7.3 (Rev 1) March 2022 Protection of Nuclear Technology and Operations
CNS-TAST-GD-7.4 (Rev 1) March 2022Physical Protection of Information
CNSS-TAST-GD-7.5 (Rev 3) March 2024Preparation for and Response to Cyber Security Events
CNS-TAST-GD-8.1 (Rev 1) November 2024 Cooperation of Departments with responsibility for delivering vetting and ongoing personnel security arrangements
CNS-TAST-GD-8.2 (Rev 1) November 2024Pre-employment Screening and National Security Vetting
CNS-TAST-GD-8.3 (Rev 1) November 2024Ongoing Personnel Security Aftercare
CNS-TAST-GD-9.1 (Rev 1) March 2024 CNC Response Force
CNS-TAST-GD-9.2 (Rev 1) March 2024Local Police Forces
CNS-TAST-GD-9.3 (Rev 1) March 2024Security Guard Services
CNS-TAST-GD-10.1 (Rev 2) October 2024CT Measures EP&R Planning
CNS-TAST-GD-10.2 (Rev 2) October 2024Testing and Exercising the Security Response
CNS-TAST-GD-10.3 (Rev 2) October 2021Clarity of C3 Arrangements for Nuclear Security Events
CNSS-TAST-GD-11.1 (Issue 1.2) May 2026 Guidance on the Security Assessment of Generic New Nuclear Reactor Designs
Safeguards
SG-TAST-GD-001 (Rev 3) January 2023 Safeguards technical assessment guidance
SG-TAST-GD-002 (Rev 1) January 2022 Nuclear Material Accountancy