Office for Nuclear Regulation, Environment Agency & Natural Resources Wales

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Regulatory Observations and Resolution Plans

On this page you will find detail of each Regulatory Observation and the associated Resolution Plan.

Regulatory Observation title RO ref. RO res plan ref. Closure letter
Avoidance of Fracture - Margins Based on the Size of Crack-Like Defects RO-ABWR-0001 RO-ABWR-0001 res plan RO-ABWR-0001 closure letter
CRD Penetration Design RO-ABWR-0002 RO-ABWR-0002 res plan RO-ABWR-0002 closure letter
RPV Design RO-ABWR-0003 RO-ABWR-0003 res plan RO-ABWR-0003 closure letter
Material/Forging/Weld/Clad Specifications for RPV Pressure Boundary RO-ABWR-0004 RO-ABWR-0004 res plan RO-ABWR-0004 closure letter
Hitachi-GE Nuclear Energy Human Factors Specialist Resource and Organisation RO-ABWR-0005 RO-ABWR-0005 res plan RO-ABWR-0005 closure letter
Source Terms RO-ABWR-0006 RO-ABWR-0006 res plan RO-ABWR-0006 closure letter
Spurious C&I Failures as Design Basis Initiating Events RO-ABWR-0007 RO-ABWR-0007 res plan RO-ABWR-0007 closure letter
Common cause failure of electrical distribution systems RO-ABWR-0008 RO-ABWR-0008 res plan RO-ABWR-0008 closure letter
Analysis of Loss of Offsite Power Events RO-ABWR-0009 RO-ABWR-0009 res plan RO-ABWR-0009 closure letter
Design Basis Analysis of Essential Services and Support Systems RO-ABWR-0010 RO-ABWR-0010 res plan RO-ABWR-0010 closure letter
Safety Case for Spent Fuel Pool and Fuel Route RO-ABWR-0011 RO-ABWR-0011 res plan RO-ABWR-0011 closure letter
Presence of Single Doors on Class 1 Nuclear Safety Barriers RO-ABWR-0012 RO-ABWR-0012 res plan RO-ABWR-0012 closure letter
Probabilistic Safety Analysis: Project Plan and Delivery RO-ABWR-0013 RO-ABWR-0013 res plan RO-ABWR-0013 closure letter
Radiological Protection Safety Case: Project Plan and Delivery RO-ABWR-0014 RO-ABWR-0014 res plan RO-ABWR-0014 closure letter
Mechanical engineering SSCs qualification and layout provision RO-ABWR-0015 RO-ABWR-0015 res plan RO-ABWR-0015 closure letter
Mechanical Engineering Design Process Arrangement RO-ABWR-0016 RO-ABWR-0016 res plan RO-ABWR-0016 closure letter
Nuclear Ventilation Codes and Standards RO-ABWR-0017 RO-ABWR-0017 res plan RO-ABWR-0017 closure letter
Examination, Inspection Maintenance and Testing (EIM&T) Isolations and Configurations RO-ABWR-0018 RO-ABWR-0018 res plan RO-ABWR-0018 closure letter
Reactor Chemistry Safety Case: Strategy, Plan and Delivery RO-ABWR-0019 RO-ABWR-0019 res plan RO-ABWR-0019 closure letter
Internal Hazards Safety Case for the Main Steam Tunnel Room RO-ABWR-0020 RO-ABWR-0020 res plan RO-ABWR-0020 closure letter
Limits and conditions of operation for Interim Dry Fuel Storage RO-ABWR-0021 RO-ABWR-0021 res plan RO-ABWR-0021 closure letter
Primary Cooling System Chemistry ALARP RO-ABWR-0022 RO-ABWR-0022 res plan RO-ABWR-0022 closure letter
Severe Accident Safety Case RO-ABWR-0023 RO-ABWR-0023 res plan RO-ABWR-0023 closure letter
Human Reliability Analysis – Error of Commission / misdiagnosis RO-ABWR-0024 RO-ABWR-0024 res plan RO-ABWR-0024 closure letter
Hitachi-GE Nuclear Energy Ltd. Safety Case Process and Capability RO-ABWR-0025 RO-ABWR-0025 res plan RO-ABWR-0025 closure letter
Back-up Building C & I RO-ABWR-0026 RO-ABWR-0026 res plan RO-ABWR-0026 closure letter
Hardwired Back Up System RO-ABWR-0027 RO-ABWR-0027 res plan RO-ABWR-0027 closure letter
Safety System Logic & Control (SSLC) Class 1 HMI RO-ABWR-0028 RO-ABWR-0028 res plan RO-ABWR-0028 closure letter
SSLC Production Excellence RO-ABWR-0029 RO-ABWR-0029 res plan RO-ABWR-0029 closure letter
Embedded C&I subsystems and smart devices RO-ABWR-0030 RO-ABWR-0030 res plan RO-ABWR-0030 closure letter
SSLC and Support System Architecture RO-ABWR-0031 RO-ABWR-0031 res plan RO-ABWR-0031 closure letter
Safety System Logic & Control (SSLC) Design RO-ABWR-0032 RO-ABWR-0032 res plan RO-ABWR-0032 closure letter
Human Reliability Analysis – Error of Commission / misdiagnosis RO-ABWR-0033 RO-ABWR-0033 res plan RO-ABWR-0033 closure letter
Demonstrating the inclusion of a 'bottom drain line' in the UK ABWR design achieves inherent safety and reduces risks SFAIRP RO-ABWR-0034 RO-ABWR-0034 res plan RO-ABWR-0034 closure letter
Robust justification for the materials selected for UK ABWR RO-ABWR-0035 RO-ABWR-0035 res plan RO-ABWR-0035 closure letter
Demonstration that the approach taken to radioactive waste management reduces risks SFAIRP RO-ABWR-0036 RO-ABWR-0036 res plan RO-ABWR-0036 closure letter
Safety Case for Faults not Directly Related to the Reactor RO-ABWR-0037 RO-ABWR-0037 res plan RO-ABWR-0037 closure letter
Additional electrical power source RO-ABWR-0038 RO-ABWR-0038 res plan RO-ABWR-0038 closure letter
UK learning from the Fukushima Dai-ichi events RO-ABWR-0039 RO-ABWR-0039 res plan RO-ABWR-0039 closure letter
Probabilistic Safety Analysis: Identification of Applicable Internal Hazards RO-ABWR-0040 RO-ABWR-0040 res plan RO-ABWR-0040 closure letter
Probabilistic Safety Analysis: Identification of Applicable External Hazards RO-ABWR-0041 RO-ABWR-0041 res plan RO-ABWR-0041 closure letter
Probabilistic Safety Analysis (PSA) internal initiating events at power RO-ABWR-0042 RO-ABWR-0042 res plan RO-ABWR-0042 closure letter
Demonstration of the adequacy of pH control in the Suppression Pool during accident conditions RO-ABWR-0043 RO-ABWR-0043 res plan RO-ABWR-0043 closure letter
Demonstration UK ABWR has been designed to safely manage radiolysis gases generated under normal operations RO-ABWR-0044 RO-ABWR-0044 res plan RO-ABWR-0044 closure letter
Operational Experience (OPEX) RO-ABWR-0045 RO-ABWR-0045 res plan RO-ABWR-0045 closure letter
Containment Performance Analyses for Severe Accidents RO-ABWR-0046 RO-ABWR-0046 res plan RO-ABWR-0046 closure letter
Mechanical Engineering – Wet Lifting Beams – Material of Construction RO-ABWR-0047 RO-ABWR-0047 res plan RO-ABWR-0047 closure letter
Probabilistic Safety Analysis: Level 2 PSA methodology RO-ABWR-0048 RO-ABWR-0048 res plan RO-ABWR-0048 closure letter
Mechanical Engineering – Dropped Load Counter Measures RO-ABWR-0049 RO-ABWR-0049 res plan RO-ABWR-0049 closure letter
Mechanical Engineering – Crane control measures RO-ABWR-0050 RO-ABWR-0050 res plan RO-ABWR-0050 closure letter
Mechanical Engineering – SSCs Qualification RO-ABWR-0051 RO-ABWR-0051 res plan RO-ABWR-0051 closure letter
Mechanical Engineering - Design Process - SSCs' Detailed Design RO-ABWR-0052 RO-ABWR-0052 res plan RO-ABWR-0052 closure letter
Probabilistic Safety Analysis (PSA) – level 1 and level 2 PSA for internal events during operation at power - System Analyses RO-ABWR-0053 RO-ABWR-0053 res plan RO-ABWR-0053 closure letter
Chemical/Process Engineering Design Approach RO-ABWR-0054 RO-ABWR-0054 res plan RO-ABWR-0054 closure letter
UK ABWR Generic Site Envelope - Seismic Hazard Definition RO-ABWR-0055 RO-ABWR-0055 res plan RO-ABWR-0055 closure letter
Demonstration that adequate optioneering has been carried out for the removal of Spent Fuel from the Reactor Building RO-ABWR-0056 RO-ABWR-0056 res plan RO-ABWR-0056 closure letter
Hitachi-GE's development of arrangements for the safety case to be met in practice RO-ABWR-0057 RO-ABWR-0057 res plan RO-ABWR-0057 closure letter
Step 3 MSQA Improvement Actions RO-ABWR-0058 RO-ABWR-0058 res plan RO-ABWR-0058 closure letter
Provision of Water Cooling for the RCCV Drywell Head of the UK ABWR RO-ABWR-0059 RO-ABWR-0059 res plan RO-ABWR-0059 closure letter
Environmental impact of emissions to air from diesel generators RO-ABWR-0060 RO-ABWR-0060 res plan RO-ABWR-0060 closure letter
Reactor Pressure Vessel Instrumentation Connections RO-ABWR-0061 RO-ABWR-0061 res plan RO-ABWR-0061 closure letter
Testing and Maintenance of Safety Systems RO-ABWR-0062 RO-ABWR-0062 res plan RO-ABWR-0062 closure letter
ABWR compliance with UK grid code RO-ABWR-0063 RO-ABWR-0063 res plan RO-ABWR-0063 closure letter
Design approach to identification and provision of both permanent and temporary features necessary for the adequate control of radioactive contamination across the full lifetime of UKABWR RO-ABWR-0064 RO-ABWR-0064 res plan RO-ABWR-0064 closure letter
Demonstration of adequate design and implementation of inherently safe techniques and structures to minimise radiation dose rates via through wall penetrations during all operating modes and for the lifetime of the facility, whilst being cognisant of design requirements relating to other discipline areas RO-ABWR-0065 RO-ABWR-0065 res plan RO-ABWR-0065 closure letter
Demonstration of suitable and sufficient consideration of chemistry effects in fault analysis RO-ABWR-0066 RO-ABWR-0066 res plan RO-ABWR-0066 closure letter
UK ABWR Generic Site Envelope - External Flooding and Beyond Design Basis events RO-ABWR-0067 RO-ABWR-0067 res plan RO-ABWR-0067 closure letter
Civil Engineering Step 3 GDA Observation on Seismic Analysis Methodology RO-ABWR-0068 RO-ABWR-0068 res plan RO-ABWR-0068 closure letter
HMI: Strategy, Application and Cognitive Issues RO-ABWR-0069 RO-ABWR-0069 res plan RO-ABWR-0068 closure letter
Discharges to surface waters RO-ABWR-0070 RO-ABWR-0070 res plan RO-ABWR-0070 closure letter
Turbine Gland Steam System: Discharges and Optimisation RO-ABWR-0071 RO-ABWR-0071 res plan RO-ABWR-0071 closure letter
Suitable and sufficient consideration of chemistry control during UK ABWR commissioning RO-ABWR-0072 RO-ABWR-0072 res plan RO-ABWR-0072 closure letter
Robust demonstration that the design of the UK ABWR off-gas system reduces risks SFAIRP RO-ABWR-0073 RO-ABWR-0073 res plan RO-ABWR-0073 closure letter
6.9kV Switchgear design for UK ABWR RO-ABWR-0074 RO-ABWR-0074 res plan RO-ABWR-0074 closure letter
Robust demonstration that the design of the UK ABWR HVAC system has been adequately conceived and reduces risks SFAIRP RO-ABWR-0075 RO-ABWR-0075 res plan RO-ABWR-0075 closure letter
PSA ALARP Demonstration and Optioneering RO-ABWR-0076 RO-ABWR-0076 res plan RO-ABWR-0076 closure letter
Demonstration of adequate protection for Pellet-cladding Interaction in response to Control-rod Movement Faults RO-ABWR-0077 RO-ABWR-0077 res plan RO-ABWR-0077 closure letter
Exceptions to Segregation RO-ABWR-0078 RO-ABWR-0078 res plan RO-ABWR-0078 closure letter
Turbine Disintegration Safety Case RO-ABWR-0079 RO-ABWR-0079 res plan RO-ABWR-0079 closure letter
Development of Spent Fuel Export Contingency Arrangements RO-ABWR-0080 RO-ABWR-0080 res plan RO-ABWR-0080 closure letter
UK ABWR Sampling Capabilities RO-ABWR-0081 RO-ABWR-0081 res plan RO-ABWR-0081 closure letter
Substantiation of the UK ABWR Class 1 Barriers against Internal Hazard Loads RO-ABWR-0082 RO-ABWR-0082 res plan RO-ABWR-0082 closure letter