title: "Nuclear Site Licence Conditions (LC 1-36)" type: wiki source: onr.org.uk anchored_to: sources/onr/nuclear-site-licence-conditions.md updated: 2026-04-10 tags: [onr, nuclear, safety, licence-conditions, nia-1965, nuclear-site-licence, new-build]
Nuclear Site Licence Conditions (LC 1-36)
What they are and how they work
Every nuclear installation in Great Britain operates under a nuclear site licence granted by the Office for Nuclear Regulation (ONR) under the Nuclear Installations Act 1965. Section 4 of that Act requires ONR to attach to each licence conditions it considers necessary or desirable for safety.
ONR uses a standard set of 36 licence conditions (LCs), drawn from Schedule 2 of the standard nuclear site licence, attached in essentially identical form to all licensed sites. They apply across the full lifecycle: design, procurement, construction, commissioning, operation, maintenance, modification, decommissioning and clean-up. ONR may add, vary or revoke conditions at any time.
Most conditions follow a standard pattern: the licensee must make and implement adequate arrangements for a given topic, submit them to ONR for approval where specified, and not alter approved arrangements without further ONR approval. This gives ONR six legally binding powers within the conditions: directions, consents, approvals, notifications, specifications, and agreements.
The conditions are goal-setting rather than prescriptive. Licensees develop their own compliance arrangements. ONR assesses whether those arrangements are adequate.
The 36 conditions: grouped summary
Group 1 - Licensee administration (LC 1-5)
| LC | Title | Core obligation |
|---|---|---|
| 1 | Interpretation | Defines all terms used across the 36 conditions |
| 2 | Marking of the site boundary | Mark and maintain boundary; prevent unauthorised access |
| 3 | Control of property transactions | Classify all property transactions by safety significance; ONR consent required for freehold/leasehold transfers |
| 4 | Restrictions on nuclear matter on the site | Approved arrangements for bringing nuclear matter onto or storing it on site; ONR consent for first-time import at new installations |
| 5 | Consignment of nuclear matter | ONR consent to send nuclear matter to a non-licensed site; 30-year records (50 years if lost or stolen) |
Group 2 - Control of operations (LC 6-12)
| LC | Title | Core obligation |
|---|---|---|
| 6 | Documents, records, authorities and certificates | 30-year record retention for all licence-related documents and approvals |
| 7 | Incidents on the site | Notify, record, investigate and report all incidents; ONR may specify which incidents |
| 8 | Warning notices | Post notices covering emergency signals, exits and emergency procedures |
| 9 | Instructions to persons on the site | Brief everyone on site about risks, precautions and emergency actions |
| 10 | Training | Approved training arrangements for all staff with safety responsibilities |
| 11 | Emergency arrangements | Approved emergency plans; consult external bodies; rehearse at required intervals |
| 12 | Duly authorised and other suitably qualified and experienced persons | Only qualified and experienced persons may perform safety-significant duties; appoint duly authorised persons (DAPs) to supervise; ONR may disqualify a DAP |
Group 3 - Nuclear safety committee and safety documentation (LC 13-16)
| LC | Title | Core obligation |
|---|---|---|
| 13 | Nuclear safety committee | Establish a committee (minimum 7 members, at least 1 independent); minutes to ONR within 14 days; ONR must be told of rejected advice |
| 14 | Safety documentation | Produce and maintain safety cases across all lifecycle phases; ONR may require any documentation |
| 15 | Periodic review | Periodic systematic review of safety cases (10-year PSR cycle for operating reactors); ONR may direct a review at any time |
| 16 | Site plans, designs and specifications | Submit site plan with schedule of all buildings and plant; update ONR immediately on changes |
Group 4 - Operational management (LC 17-22)
| LC | Title | Core obligation |
|---|---|---|
| 17 | Management systems | Management systems must give due priority to safety; approved quality management arrangements |
| 18 | Radiological protection | Assess average effective doses for specified classes; notify ONR if doses exceed specified levels |
| 19 | Construction or installation of new plant | Approved arrangements for all new plant; staged construction with ONR consent gates where specified; ONR may halt construction |
| 20 | Modification to design of plant under construction | Classify design modifications by safety significance; staged consent mechanism |
| 21 | Commissioning | Staged commissioning with consent gates; no normal operation until commissioning complete and safety case assessed; ONR may withhold consent to operate |
| 22 | Modification or experiment on existing plant | Classify modifications and experiments by safety significance; staged consent; ONR may direct a halt |
Group 5 - Operating records and controls (LC 23-28)
| LC | Title | Core obligation |
|---|---|---|
| 23 | Operating rules | Produce a safety case identifying operating conditions and limits; comply with operating rules at all times; ONR may approve specific rules |
| 24 | Operating instructions | All safety-affecting operations must follow written instructions that implement the operating rules |
| 25 | Operational records | Records of operation, inspection and maintenance including all radioactive material and waste on site |
| 26 | Control and supervision of operations | Safety-affecting operations may only be performed under supervision of a qualified and experienced person |
| 27 | Safety mechanisms, devices and circuits | Plant may not be operated, inspected, maintained or tested unless safety systems are connected and working |
| 28 | Examination, inspection, maintenance and testing | Regular systematic EIMT under approved arrangements; plant maintenance schedule; report any safety concern immediately under LC 7 |
Group 6 - Emergency and decommissioning (LC 29-36)
| LC | Title | Core obligation |
|---|---|---|
| 29 | Duty to carry out tests, inspections and examinations | ONR may specify additional tests beyond LC 28; results to ONR promptly |
| 30 | Periodic shutdown | Shut down plant for scheduled maintenance as required; ONR may extend operating period; ONR consent for restart where specified |
| 31 | Shutdown of specified operations | ONR may direct immediate shutdown of any operation; restart requires ONR consent |
| 32 | Accumulation of radioactive waste | Minimise waste accumulation ALARP; record all waste; comply with ONR-specified quantity/form limitations |
| 33 | Disposal of radioactive waste | ONR may direct disposal in accordance with environmental permit |
| 34 | Leakage and escape of radioactive material and radioactive waste | Contain radioactive material ALARP; detect and report any leak under LC 7; does not restrict authorised discharges |
| 35 | Decommissioning | Approved decommissioning arrangements and programmes for each plant; staged with consent gates; ONR may direct commencement or halt |
| 36 | Organisational capability | Maintain adequate financial and human resources; approved arrangements for managing organisational change; ONR may halt a change |
Relationship to the ONR regulatory regime
ONR operates a permissioning regime. The most significant regulatory interactions take place where a condition requires ONR consent, approval or notification before the licensee may act. These are legally binding where explicitly stated in the condition text.
ONR's Safety Assessment Principles (SAPs) and Technical Assessment Guides (TAGs) provide the criteria against which inspectors assess whether licensee arrangements are adequate. Compliance with licence conditions is likely to satisfy related HSWA duties, though HSWA compliance must be separately demonstrated.
Key conditions for new build (NPS EN-7 context)
NPS EN-7 (Nuclear Power Generation, 2025) sits alongside the nuclear site licence. A new nuclear power station requires both a Development Consent Order (DCO) from the Secretary of State and a nuclear site licence from ONR. This dual-consent requirement means NPS EN-7 cannot override any licensing condition.
The conditions most actively engaged during the new build phase are:
- LC 4 - first-time import of nuclear fuel requires ONR consent
- LC 15 - safety case review arrangements must be in place from the start
- LC 19 - all construction stages require approved arrangements; ONR consent gates at each stage
- LC 20 - any design change during construction must be classified and justified
- LC 21 - commissioning is staged with consent gates; no operation until commissioning complete and safety case approved
- LC 22 - once plant exists, any modification requires classification and may require consent
For small modular reactors (SMRs), the same 36 conditions apply. Generic design assessment (GDA) allows certain aspects of safety to be assessed in advance, but the LC framework is applied to the specific site and licensee.
Enforcement powers
ONR may enforce licence conditions through:
- Directions - directly requiring the licensee to do something (binding)
- Consents - authorisation to proceed with a specified action; can be withheld
- Approvals - freeze arrangements so they cannot be changed without further approval
- Specifications - require information or specify how something must be done
- Improvement notices and prohibition notices under HSWA 1974
- Prosecution under NIA 1965 or HSWA 1974
ONR may also revoke the nuclear site licence, though this is rare. The most common enforcement route for licence condition failures is the improvement notice, which sets a timetable for compliance.
Key conditions in ONR enforcement practice
LC 14 and LC 15 (safety documentation and periodic review): The continuous safety case requirement. LC 14 requires the case to exist; LC 15 requires it to be kept current through systematic review. The ten-year PSR cycle governs whether operating reactors may continue. Major ONR regulatory interventions on operating stations are typically framed under these two conditions.
LC 22 (modification control): The central day-to-day interface between ONR inspectors and licensee engineering teams. Every physical or procedural change must pass the LC 22 classification and justification process. Failures - inadequate justification, proceeding without consent, misclassifying safety significance - are the most common trigger for formal enforcement action.
LC 32 (radioactive waste accumulation): The ALARP obligation applies to waste accumulation at long-term storage sites. ONR quantity and form limitations under LC 32 paragraph 4 can constrain site operations.
LC 36 (organisational capability): Covers financial resource adequacy as well as personnel. ONR uses this condition to scrutinise outsourcing arrangements, supply chain dependency, and corporate ownership changes. Increasingly relevant in transactions involving licensed site operations.
Primary source: ONR Licence Condition Handbook (October 2014 / February 2017 update), Schedule 2 of the standard nuclear site licence. Published under Open Government Licence v2.0.