Office For Nuclear Regulation Research Articles

Designing and implementing temporary works schemes on UK nuclear licensed sites

Nuclear projects in the UK demand high levels of assurance and substantiation during both design and construction. As a result, site licensees must demonstrate control over construction works in the vicinity of, or modifications to safety-related structures, systems and components in accordance with their nuclear site licence conditions. Furthermore, the Office for Nuclear Regulation will scrutinise designs, management controls and processes prior to permissioning the works. This paper discusses examples of additional considerations for the design and implementation of temporary works during the construction phase to demonstrate compliance with the regulators, Safety Assessment Principles and licence conditions, and to demonstrate that nuclear safety risks have been reduced to as low as reasonably practicable. References of good practice are from a confidential BAE Systems project in Cumbria, UK, titled D58, involving nuclear Class 1 concrete construction and informing of the steps taken to obtain Nuclear Safety Committee and regulatory permissioning.

Monte Carlo Investigation of the UK’s First EPR Nuclear Reactor Startup Core Using Serpent

Computationally modelling a nuclear reactor startup core for a benchmark against the existing models is highly desirable for an independent assessment informing nuclear engineers and energy policymakers. For the first time, this work presents a startup core model of the UK’s first Evolutionary Pressurised Water Reactor (EPR) based on Monte Carlo simulations of particle collisions using Serpent 2, a state-of-the-art continuous-energy Monte Carlo reactor physics burnup code. Coupling between neutronics and thermal-hydraulic conditions with the fuel depletion is incorporated into the multi-dimensional branches, obtaining the thermal flux and fission reaction rate (power) distributions radially and axially from the three dimensional (3D) single assembly level to a 3D full core. Shannon entropy is quantified to characterise the convergence behaviour of the fission source distribution, with 3 billion neutron histories tracked by parallel computing. Source biasing is applied for the variance reduction. Benchmarking the proposed Monte Carlo 3D full-core model against the traditional deterministic transport computation suite used by the UK Office for Nuclear Regulation (ONR), a reasonably good agreement within statistics is demonstrated for the safety-related reactivity coefficients, which creates trust in the EPR safety report and informs the decision-making by energy regulatory bodies and global partners.

An accident scenario-based statistical test method for RPS in nuclear power plant

RPS (Reactor Protection System) plays a critical role in assuring safety operation and relieves the consequence of accident in Nuclear Power Plant (NPP). With widely use of digital instrumentation and control (I&C) system, since LingAo phase II, Chinese NPP started the introduction of digital I&C system. After ten years of effort, the first domestic independent researched and developed digital I&C system, which named FirmSys, has been deployed in Yang Jiang NPP and intended to export with 3rd generation HPR1000 reactor to the UK. To achieve this export, the method to satisfy generic design assessment (GDA) requirements from the office for nuclear regulation (ONR) of UK is being explored. Statistical test is a recommendation way for independent confidence-building measure (ICBM) and production excellence (PE) of GDA. According to the requirements of statistical test from standard IEC 60880, and with the analysis of current test method limitation in test coverage and operation state simulation, the content and process design is the key point for statistical test in finite test times. For safety critical software in nuclear power plant, whose probability of failure is very small, the critical operation of dealing with accident for avoiding of disaster by user will rarely happen but requires high reliability. Therefore, the common practice of statistical test could not make a sufficient test for the operation during accident happening, and the cost of test is unacceptable. This paper proposes a scenario-based innovation statistical test method for RPS, and describes the test architecture, process, and achievement. This method uses accident scene as test case that focus on the protection functions, it covers parameters, values, operation states, and protection actions. All selected scenes is designed to occur in their relatively probability, target systems are responding in real input and output environment to prove their protection ability as the accident is really happening. Meanwhile, to test the effectiveness of redundant design, channels are randomly selected for success data transform while others are set failure. At last, an engineering practice with this scenario-based test method is made on FirmSys, the pressure water reactor typical accident scenes LOCA, SGTR and MSLB have been successfully simulated, achieves protection sequence verification with high parameters coverage during parameters constantly variation. This method also provides reference for system verification, reliability evaluation and GDA, and be applied in engineering project.

Energy Supply and Decarbonisation Beyond Brexit: Politics and Policy

Energy Supply and Decarbonisation Beyond Brexit: Politics and Policy

The susceptibility of glacigenic deposits to liquefaction under seismic loading conditions: a case study relating to nuclear site characterization in West Cumbria

Previous research has established a chronostratigraphy of glacial/deglacial events together with a lithostratigraphical framework for the Quaternary deposits of the Sellafield area in West Cumbria. The glacial record is dominated by sediments and landforms laid down during the deglaciation of the Devensian ice sheet. The Quaternary deposits are characterized by complex sequences resulting from oscillating ice sheet margins, changing glacial lake and outwash environments, relative sea level changes and glacio-tectonic deformation. The resulting deposits comprise sequences which possess a wide range of grain size, shape and sorting; some are normally consolidated and have very low to low in situ density. An understanding of the geotechnical behaviour of these deposits is critical during geological site characterization studies for the design of new buildings and infrastructure on existing and proposed nuclear sites. The geotechnical engineering behaviour of a sequence of glacial deposits on the Sellafield nuclear site is evaluated together with their susceptibility to potential liquefaction under certain seismic load conditions. The evaluation identified that layers of very loose to loose deposits within the ice sheet marginal landsystem are particularly susceptible to liquefaction under specified seismic loading conditions that are required to be modelled by the UK Office for Nuclear Regulation (ONR).

The Position and Roles of Occupational Health and Safety Functions in the UK Risk Management System

Studying the crisis management systems of other developed countries has been effective in clarifying what the position and roles of occupational health and safety functions should be in the crisis management system in Japan. In addition to previous studies on the US system, we studied the UK system. We gathered relevant information by visiting the headquarters of the Health and Safety Executive (HSE) and the Office for Nuclear Regulation (ONR), as well as obtaining information available via the internet. In the UK, the crisis management system was developed based on the Civil Contingencies Act of 2004, which regulated the system of planning and actual correspondence. The system was established with a framework that is consistent at both the national and local levels regardless of the type of crisis. The HSE has health and safety experts involved in all aspects and levels of the crisis management system. The HSE and ONR also assist in emergency planning for serious accidents involving chemical and radioactive substances. We observed the following three common features for ensuring the health and safety of crisis responders in the US and UK: 1) establishing an all-hazard model, a common crisis response system for all types of crisis, 2) ensuring functions to protect the health and safety of workers in a crisis at the national and local levels, 3) ensuring provision of expertise on health and safety for effective management during a crisis. These findings should be used to improve the system in Japan.

Safety Demonstration of a Class 1 Smart Device

Horizon Nuclear Power intends to build advanced boiling water reactors at Wylfa and Oldbury in the United Kingdom based on the Hitachi-GE (Hitachi) design. In accordance with U.K. policy for new nuclear build, Hitachi, as the reactor designer, is the requesting party to the Generic Design Assessment (GDA), during which the reactor design will be reviewed by the Office for Nuclear Regulation and the Environment Agency. An important step in the GDA process is to demonstrate the viability of the approach developed by Hitachi-GE for the assessment and justification of smart devices. This was done by means of pilot studies of safety class 1 (SC1) and SC2 devices. This paper describes the scope, criteria, process, and approach for the SC1 pilot study and summarizes the results of the study.

Publisher Correction: Science and research policy at the end of Moore’s law

In the version of this Perspective originally published, in the penultimate paragraph 'Office for Nuclear Regulation' should have read 'Office of Naval Research'. This has now been corrected.

Off-site Emergency Planning at UK Nuclear Licensed Sites.

Nuclear emergency planning arrangements in the UK are continually kept under review. This work proposes to outline how experience from nuclear exercises and undertaking emergency response duties can be based on radiological knowledge of specific sites and utilised in the future. In 2014, the UK regulator, the Office for Nuclear Regulation (ONR) revised their principles for the determination of off-site emergency planning areas around nuclear sites where predetermined countermeasures and other protection measures are applied to protect those people who may be affected by a radiation emergency. The revised principles also enhanced communication from the nuclear site operators and local authorities to the public. This updated ONR's application of the UK Radiation (Emergency Preparedness and Public Information) Regulations 2001 (REPPIR) http://www.hse.gov.uk/radiation/ionising/reppir.htm, which includes details of minimising potential doses to the public, as well as assessment and reassurance, linked to other concurrent risks such as flooding. ONR undertakes site-specific assessments of each operators' hazard identification and risk evaluation, which include consideration of whether the public might receive a significant radiation dose in the year following the emergency (excluding countermeasures in the first 24 hours). In defining the areas for off-site emergency planning, practical and strategic factors are then considered, which include other local non-nuclear emergency planning arrangements and experience, and whether local geographic and demographic aspects could aid public credibility and confidence.

Practical experience of failure analysis on nuclear facility or how I learned to love a well-structured FMEA

The safety assessment principles for nuclear facilities, produced by the Office for Nuclear Regulation (ONR), define Engineering Principles which require a formal and structured analysis to be undertaken to identify all potential failure modes for structures, systems and components important to safety within a nuclear facility.It has been widely publicised, for example in “Mitigating the Loss of Critical Knowledge” by Bell (2014), that there is a skills shortage in engineering design assurance in highly regulated industries within the UK. This paper presents examples and lessons learnt from 5 years of practical experience in performing structured failure analysis, particularly Failure, Modes and Effects Analysis (FMEA), on nuclear facility design: these lessons learnt are considered applicable to all highly regulated industries. It is hoped that the following examples included in this report, might inspire and guide others in the development of FMEA in support of design assurance activities:Tailoring the level at which FMEA is undertaken to the nuclear classification of the safety function; detailed component level FMEA for higher level safety functions, and high level functional FMEA for lower level safety functions;Running the FMEA in parallel with design development and working with the design engineers to ensure results from the FMEA can influence the design at the appropriate time;Using FMEA to identify design mitigation and Examination, Maintenance, Inspection and Test (EMIT) recommendations during early phases of the design;Using FMEA to identify redundancy within a design to reduce the maintenance burden through life;Inclusion of component failure mode failure rate data to calculate the Probability of Failure on Demand (PFD) of safety functions;Inclusion of dependability analysis between systems to calculate the PFD of a higher level function;The positive impact of integrating Human Factors (HF) assessors in the development of the failure analysis.

Impact of Fukushima disaster on international nuclear transport safety: UK perspective

On 11 March 2011, Japan was struck by an earthquake measuring over 9·0 on the Richter magnitude scale, the strongest known to hit Japan and one of the top five largest earthquakes ever recorded in the world. The epicentre was 175 km (110 miles) east-north-east from the Fukushima Daiichi nuclear power plant, and within an hour a massive tsunami had inundated the site. This caused a serious nuclear accident, with an International Nuclear and Radiological Event Scale (INES) rating of Level 7 (the highest). Following the events at Fukushima, the nuclear industry in the UK responded quickly to review UK nuclear installations against seismic and flooding hazards. On 14 March 2011 the UK Secretary of State for Energy and Climate Change requested that Dr Mike Weightman, HM Chief Inspector of Nuclear Installations, examine the circumstances of the Fukushima accident to see what lessons could be learnt to enhance the safety of the UK nuclear industry. An Interim Report was published in the middle of May 2011, with a Final Report six months later. A further report was published in October 2012 that provided an update on progress in implementing the lessons for the UK’s nuclear industry. In addition to the Weightman Reports, the UK Office for Nuclear Regulation (ONR) produced two national reports on the European Council ‘Stress Tests’ focusing on licensed nuclear sites. The first covered all civil nuclear power plants with the second, on the instructions of the Chief Inspector, covering all of the remaining UK nuclear installations. In both these reports, areas for potential improvement (known as ‘considerations’) were identified by licensees and these were augmented by Stress Test Findings identified by ONR. The key findings of these reports are reviewed, with the objective of extracting and drawing out key learning which could translate to and impact nuclear transport safety. The potential impact of these findings on INS and its nuclear transport operations is assessed, and the progress made to date reported.