Office for Nuclear Regulation

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Office for Nuclear Regulation (ONR) 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


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Document ID Review date Title
Nuclear safety
NS-TAST-GD-002 (Rev 7) June 2022 Radiation Shielding
NS-TAST-GD-003 (Rev 8) March 2021 Safety Systems
NS-TAST-GD-004 (Rev 7) April 2022 Fundamental Principles
NS-TAST-GD-005 (Rev 10) December 2022 Guidance on the Demonstration of ALARP (As Low As Reasonably Practicable)
NS-TAST-GD-006 (Rev 4) Withdrawn pending review Deterministic Safety Analysis and The Use of Engineering Principles in Safety Assessment
NS-TAST-GD-007 (Rev 4) September 2020 Severe Accident Analysis
NS-TAST-GD-009 (Rev 5) November 2021 Examination, Inspection, Maintenance and Testing of Items Important to Safety
NS-TAST-GD-010 (Rev 5) May 2020 Early initiation of safety systems
NS-TAST-GD-011 (Rev 2) Withdrawn pending review The single failure criterion
NS-TAST-GD-013 (Rev 7) October 2021 External hazards
NS-TAST-GD-014 (Rev 5) November 2022 Internal Hazards
NS-TAST-GD-015 (Rev 2) Withdrawn pending review Electromagnetic compatibility
NS-TAST-GD-016 (Rev 5) March 2020 Integrity of Metal Components and Structures
NS-TAST-GD-017 (Rev 3) Withdrawn pending review Civil Engineering
NS-TAST-GD-018 (Rev 7) June 2022 Criticality Warning Systems
NS-TAST-GD-019 (Rev 4) July 2022 Essential Services
NS-TAST-GD-020 (Rev 4) December 2020 Containment for Reactor Plant
NS-TAST-GD-021 (Rev 5) July 2022 Containment Chemical Plants
NS-TAST-GD-022 (Rev 5) April 2020 Ventilation
NS-TAST-GD-023 (Rev 5) August 2022 Control of Processes Involving Nuclear Matter (SAP - ENM. 1 to 8)
NS-TAST-GD-024 (Rev 6) September 2022 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) July 2020 Training and assuring personnel competence
NS-TAST-GD-028 (Rev 5) October 2022 Control and Instrumentation Aspects of Nuclear Plant Commissioning
NS-TAST-GD-029 (Rev 4) November 2021 Graphite reactor cores
NS-TAST-GD-030 (Rev 6) June 2022 Probabilistic Safety Analysis
NS-TAST-GD-031 (Rev 5) September 2021 Safety related Systems and Instrumentation
NS-TAST-GD-033 (Rev 6) February 2022 Duty Holder Management of Records
NS-TAST-GD-034 (Rev 4) April 2022 Transient Analysis for DBAs in Nuclear Reactors
NS-TAST-GD-035 (Rev 5) August 2021 The Limits and Conditions for Nuclear Safety (Operating Rules)
NS-TAST-GD-036 (Rev 4) April 2020 Diversity, redundancy, segregation and layout of mechanical plant
NS-TAST-GD-038 (Rev 8) November 2020 Radiological protection
NS-TAST-GD-041 (Rev 6) June 2022 Criticality Safety
NS-TAST-GD-042 (Rev 4) March 2022 Validation of Computer Codes and Calculation Methods
NS-TAST-GD-043 (Rev 5) July 2022 Radiological Analysis Normal Operation
NS-TAST-GD-045 (Rev 5) July 2022 Radiological analysis Fault conditions
NS-TAST-GD-046 (Rev 5) April 2022 Computer Based Safety Systems
NS-TAST-GD-048 (Rev 5) September 2021 Organisational Change
NS-TAST-GD-049 (Rev 6) April 2022 Licensee Core Safety and Intelligent Customer Capabilities
NS-TAST-GD-050 (Rev 7) July 2020 Periodic Safety Reviews (PSRs) [NS-TAST-GD-050]
NS-TAST-GD-051 (Rev 6) December 2022 The purpose, scope and content of nuclear safety cases
NS-TAST-GD-056 (Rev 6) October 2021 Nuclear Lifting Operations
NS-TAST-GD-057 (Rev 5) December 2020 Design Safety Assurance
NS-TAST-GD-058 (Rev 3) March 2020 Human factors integration
NS-TAST-GD-059 (Rev 4) November 2022 Human Machine Interface
NS-TAST-GD-060 (Rev 3) November 2020 Procedure Design and Administrative Controls
NS-TAST-GD-061 (Rev 3) March 2020 Staffing levels and task organisation
NS-TAST-GD-062 (Rev 3) February 2020 Workplaces and work environment
NS-TAST-GD-063 (Rev 4) October 2021 Human Reliability Analysis
NS-TAST-GD-064 (Rev 3) December 2020 Allocation of function between human and engineered systems
NS-TAST-GD-065 (Rev 3) August 2021 Function and content of the Nuclear Baseline
NS-TAST-GD-067 (Rev 1) November 2020 Pressure Systems Safety
NS-TAST-GD-072 (Rev 3) July 2021 Function and content of a safety management prospectus
NS-TAST-GD-075 (Rev 2) September 2020 Safety of Nuclear Fuel in Power Reactors
NS-TAST-GD-076 (Rev 4) February 2020 Construction Assurance
NS-TAST-GD-077 (Rev 5) July 2022 Supply Chain Management Arrangements for the Procurement of Nuclear Safety Related Items or Services
NS-TAST-GD-079 (Rev 4) April 2022 Licensee Design Authority Capability
NS-TAST-GD-080 (Rev 3) July 2021 Challenge Culture, Independent Challenge Capability (including an Internal Regulation function) and the Provision of Nuclear Safety Advice
NS-TAST-GD-081 (Rev 3) June 2022 Safety Aspects Specific to Storage of Spent Nuclear Fuel
NS-TAST-GD-082 (Rev 5) December 2020 The Technical Assessment of REPPIR Submissions
NS-TAST-GD-083 (Rev 1) November 2021 Land Quality Management
NS-TAST-GD-087 (Rev 1) June 2020 Control of Property Transactions on Licensed Sites
NS-TAST-GD-088 (Rev 2) January 2022 Chemistry of Operating Civil Nuclear Reactors
NS-TAST-GD-089 (Rev 0) February 2021

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 1) July 2022 Categorisation of Safety Functions and Classification of Structures and Components
NS-TAST-GD-097 (Rev 0) October 2020 Criticality Safety Assessment of Transport Packages
NS-TAST-GD-098 (Rev 1) December 2022 Asset Management
NS-TAST-GD-099 (Rev 0) April 2020 Transport Engineering Assessment
NS-TAST-GD-100 (Rev 0) April 2020 Shielding and Dose Rate Safety Assessment of Transport Packages
NS-TAST-GD-101 (Rev 0) March 2021 Geological Disposal
NS-TAST-GD-102 (Rev 0) January 2022 General Guidance for Mechanical Engineering Specialism Group
NS-TAST-GD-103  (Rev 0) February 2022 Emergency Power Generation
Civil Nuclear Security
CNS-TAST-GD-1.1 (Rev 0)March 2020Security Governance and Leadership
CNS-TAST-GD-1.2 (Rev 0)March 2020Organisational Security Capability
CNS-TAST-GD-1.3 (Rev 0)March 2020Security Decision Making
CNS-TAST-GD-1.4 (Rev 0)March 2020Organisational Learning for Security
CNS-TAST-GD-1.5 (Rev 0)March 2020Security Assurance Processes
CNS-TAST-GD-2.1 (Rev 0)March 2020Maintenance of a Robust Security Culture
CNS-TAST-GD-3.1 (Rev 0)March 2020Analysis of Security Roles & Associated Competencies
CNS-TAST-GD-3.2 (Rev 0)March 2020Identification of Learning Objectives and Training Needs
CNS-TAST-GD-3.3 (Rev 0)March 2020Measurement of Competence
CNS-TAST-GD-3.4 (Rev 0)March 2020Organisation of and Support to the Training Function
CNS-TAST-GD-4.1 (Rev 0)March 2020Procurement and Intelligent Customer Capability
CNS-TAST-GD-4.2 (Rev 0)March 2020Supplier Capability
CNS-TAST-GD-4.3 (Rev 0)March 2020Oversight of Suppliers
CNS-TAST-GD-4.4 (Rev 0)March 2020Commissioning
CNS-TAST-GD-5.1 (Rev 0)March 2020Reliability and Resilience
CNS-TAST-GD-5.2 (Rev 0)March 2020Examination, Inspection, Maintenance and Testing
CNS-TAST-GD-5.3 (Rev 0)March 2020Sustainability
CNS-TAST-GD-6.1 (Rev 0)March 2020Categorisation for Theft
CNS-TAST-GD-6.2 (Rev 0)March 2020Target Identification for Sabotage
CNS-TAST-GD-6.3 (Rev 0) March 2020 Physical Protection System Design (Offical sensitive)
CNS-TAST-GD-6.4 (Rev 0)March 2020Vulnerability Assessment
CNS-TAST-GD-6.5 (Rev 0)March 2020Adjacent or Enclave Nuclear Premises
CNS-TAST-GD-6.6 (Rev 0) March 2020 Nuclear Construction Sites
CNS-TAST-GD-6.7 (Rev 0) November 2020Class A Carrier Transport Security Statements
CNS-TAST-GD-7.1 (Rev 0)March 2020Effective Cyber and Information Risk Management
CNS-TAST-GD-7.2 (Rev 0)March 2020Information Security
CNS-TAST-GD-7.3 (Rev 0)March 2020 Protection of Nuclear Technology and Operations
CNS-TAST-GD-7.4 (Rev 0)March 2020Physical Protection of Information
CNS-TAST-GD-7.5 (Rev 1)March 2020Preparation 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 0)March 2020CNC Response Force
CNS-TAST-GD-9.2 (Rev 0)March 2020Local Police Forces
CNS-TAST-GD-9.3 (Rev 0)March 2020Security Guard Services
CNS-TAST-GD-10.1 (Rev 0)March 2020CT Measures EP&R Planning
CNS-TAST-GD-10.2 (Rev 0)March 2020Testing and Exercising the Security Response
CNS-TAST-GD-10.3 (Rev 0)March 2020Clarity of C3 Arrangements for Nuclear Security Events
CNS-TAST-GD-11.1 (Rev 0) June 2020 Guidance on the Security Assessment of Generic New Nuclear Reactor Designs