Craig has 16 years’ experience in the nuclear industry, specialising primarily in criticality safety assessments and radiation shielding assessments. He has worked for multiple clients across the UK in the civil nuclear and defence industries, including Urenco, Magnox and AWE. He has extensive experience on operational and decommissioning projects, as well as the provision of independent checking and peer review. He has particular recent experience of criticality assessments, safety case support, HAZAN production and provision of ad hoc criticality advice in his role providing support to Urenco as senior criticality safety assessor.
Craig is highly experienced in the use of radiation transport and criticality codes such as MCNP, MONK and RANKERN, including the use of variance reduction techniques, and has extensive experience in production of safety case documentation, including HAZANs, criticality safety assessments, technical reports, CWS (CIDAS) omission cases, CWS placement studies and SOE assessments. He also has significant experience in criticality emergency planning.
Craig has been a director of Cerberus Nuclear since its inception in 2016.
Tom is a chartered physicist with a PhD in Nuclear Physics and over 20 years experience as a technical specialist in the nuclear industry. He is a director of Cerberus Nuclear and joined the company in 2018. Tom has a proven ability in leadership of teams engaged in technical work on a wide variety of projects and has applied principles from his APMP project management qualification and the Sellafield Ltd Leadership Academy to consistently deliver work to time and cost.
Tom began his career as a graduate criticality safety assessor for a major defence organisation in the UK, where he worked on fissile material systems, becoming an expert user of the MONK criticality code. Subsequently, Tom moved into consultancy, gaining 8 years experience as a principal consultant in both criticality safety assessment and radiation shielding, where he made extensive use of MCNP. Following this Tom moved to Sellafield Ltd, whereupon after successfully leading a characterisation and modelling team on-site at Sellafield for four years he then joined Cerberus Nuclear as a director in 2018.
Based in Chester, Tom represents the company at the British Energy Coast Business Cluster (BECBC).
Stewart is a Chartered Physicist, criticality safety and radiation shielding assessor. He is also a co-founder and Director of Cerberus Nuclear and represents the company on the UK Working Party on Criticality (WPC).
For over 19 years Stewart has worked across the UK nuclear industry with long-term secondments to a number of key clients including URENCO, AWE, NNL (Springfield Fuels) and Sellafield Limited. His project work has involved working with other safety disciplines, design engineers, plant management and regulators to achieve fit for purpose designs and processes.
Stewart is a highly experienced user of various computer codes, including MCNP, MONK and MCBEND, and has produced validation and verification documentation for several clients. Stewart is also an effective mentor of graduate and early career criticality assessors and has extensive experience of supervising the work of trainee criticality assessors.
Dan is the radiation shielding team lead for Cerberus Nuclear.
He has over 10 years’ experience in radiation shielding design, classification of areas and dose uptake assessments and has worked many for clients across the UK and abroad. He has provided independent technical advice regarding radiation safety issues as well as peer review support. Dan is highly experienced in the use of radiation transport codes such as MCNP, SCALE as well as ATTILA and provides training and development in Monte Carlo and deterministic methods.
Dan has previously been the chair for the UK Shielding Forum (TSF) which is a UK authority for shielding principles, methodologies and core skill requirements for the nuclear industry.
Emily is the Business and Commercial Strategy Lead at Cerberus Nuclear, providing business development and management support for the company. Her responsibilities include pursuing new business opportunities, and bid writing and management. Since starting with the company she has also been involved in the implementation of the Business Management System (ISO9001, 14001 & 45001), for which Cerberus Nuclear has been UKAS Accredited.
Emily is also an experienced radiation shielding assessor with over 6 years’ experience. She was a SQEP 3 assessor for Sellafield Ltd and has worked on a range of decommissioning and new build projects supporting safety, engineering and design teams. Highly proficient in radiation transport codes such as MCNP, MCBEND and RANKERN, she has produced key documents in line with the Shielding Design Process including Shielding Design Basis, Classification of Areas, Bulk Shielding, Detailed Design support, Dose Assessment as well as CID Placement Assessments.
Commercial email: nuclear@cerberusnuclear.com
Telephone: +44(0)1925 357311
Toby is a criticality assessor with 14 years’ experience in the nuclear industry. He has carried out criticality safety assessments for operational facilities, decommissioning projects, fissile material storage facilities and of packages intended for geological disposal. He has also produced analyses to support staged safety case reports. Toby is experienced in the use of handbook data and criticality calculations using MCNP (including the Whisper package to estimate EPD) and also has MONK experience. He has written VBA and Python scripts for pre- and post-processing of calculations.
Toby has led several high-profile decommissioning criticality safety assessments at SL and AWE, including providing criticality advice to facilities and project teams. He has also been the criticality representative on HAZOPs and Human Factors reviews. Toby has also supported decommissioning work at UNS, UUK and LLWR. He is a SQEP QA checker and has contributed to peer reviews of criticality safety assessments and presented to Management Safety Committees. Toby has operational criticality assessment experience using the DBAA methodology at NNL and preliminary design phase experience, having supported Urenco’s Flexible Enrichment Module.
Toby has undertaken technical oversight and project management roles, acting as the technical point of contact on for NWS, projects for the Winfrith site, SL HAW Thermal Treatment and LLWR (HAW vaults and Silos). He has defined the technical approach required for work, managed resources and made regular project updates to client ICs.
Toby has considerable experience in criticality training. He runs Cerberus Nuclear’s Criticality College training programme for graduates and has provided training to NWS, UUK and Winfrith, including Cerberus Nuclear’s CARTA VR criticality training aid. Toby represents Cerberus Nuclear as a deputy member of the Working Party on Criticality and is a member of the Handbook Data and Criticality Training sub-groups.
Hannah is a technical specialist in the field of radiation shielding and dose assessment with 17 years’ experience. She has provided support to safety, engineering and design teams for a variety of new build, operational plant and decommissioning projects on nuclear sites across the UK, including managing the delivery of shielding support on high-profile projects such as Sellafield’s SIXEP Contingency Plant, BEPPS-DIF & Silos Direct Encapsulation Plant and AWE’s HUB. She is highly experienced in the use of radiation transport codes such as MCNP, SCALE, OpenMC, ATTILA, MCBEND & RANKERN. She has mentored many junior members of staff and has provided numerous radiation shielding training courses, both for Sellafield and for Cerberus. Hannah is responsible for coordinating the delivery of all of Cerberus Nuclear’s shielding assessments.
Daniel Murphy is a Chartered Physicist and a Radiation Shielding Consultant with 8 years’ experience in the nuclear industry in radiation shielding and operational health physics. He is an expert user of MCNP and other shielding codes and has led the shielding design on many challenging projects.
He has worked for clients across the UK nuclear industry on projects ranging from design to operation to decommissioning. Example UK projects include the SMR-300 GDA for Holtec, the HYA/HRA pressurised sand filter replacement for EDF Energy and B52 ILW retrievals for Sellafield. He has also worked on major international decommissioning projects such as at Monju, Tokai and Fukushima in Japan.
Thomas joined Cerberus Nuclear as a consultant in 2024, having previously completing a PhD and working as Teaching Fellow for the Department of Mechanical Engineering, University of Birmingham. Thomas has since completed radiation shielding projects for Urenco and AWE. His work has included using MCNP to perform bulk shielding assessments and create dose contours for both large-scale, open-air radiation environments with multiple sources, and enclosed cells with high energy accelerators.
In addition to this, Thomas has been developing software for the company’s DrumSight Game Changers project and other innovation challenges in an expanding range of industries. Most recently, Thomas has been leading the development of a Materials in Orbital Radiation Environments Database tool (MORED), funded by the UK Space Agency.
Andrew Weaver is a Criticality Safety and Radiation Shielding Consultant at Cerberus Nuclear with over a year of experience. He has become experienced in a variety of radiation transport codes, such as MCNP, OpenMC and PHITS whilst conducting a vast array of shielding assessments. He has contributed to high-energy LINAC bunker design by generating detailed source terms, analysing compound scatter angles, and evaluating material choices through cross-section analysis. He has delivered the detailed design of bespoke shield doors for a radioactive waste handling facility and undertaken a small penetrations assessment for the AWE HUB calibration facility; this involved modelling a range of radiation sources and complex geometries to develop tailored shielding solutions to reduce dose rates and meet design criteria. His work also includes shielding verification using high-density laser scanning to produce a precise 3D point cloud, enabling accurate measurement of wall and roof thicknesses, verification of shielding integrity, and determination of penetration geometry to ensure compliance with safety requirements.
Andrew’s background in field of nuclear physics research makes him particularly adept at novel project approaches. He conducted experimental studies, ion‑beam simulations, and data analysis at the IGISOL facility in Finland, before further advancing his expertise in data acquisition, electronics, and project development as a postdoctoral researcher at TRIUMF’s TITAN facility.
Daniel is a Criticality Safety Consultant with an MSc in Nuclear Science and Technology and an MPhys in Physics. Daniel is proficient with MCNP and MONK codes and has produced criticality calculations as part of transport assessment for the SWTC, in the development of the novel High Active Waste Thermal Treatment concept for PCM management, and in handbook curve generation. He has provided criticality support for numerous assessments across the Sellafield Ltd site as part of the remediation team, and has contributed to the development of the criticality strategy for the Rep-U project at Springfields Fuels Ltd.
Andrew is a consultant in the Criticality Safety and Radiation Shielding teams at Cerberus Nuclear. Since starting with the company, Andrew has worked on a number of projects, including the calculation of a variety of criticality dose contours, converting and subsequently verifying criticality calculations from SCALE to MCNP, a dose assessment for a set of large, unshielded, penetrations as part of the AWE Hub Project, as well as working on the optimisation of a shielded store for both gamma and neutron sources, and the determination of safe activity limits for a range of radionuclides in a containment vessel. Before starting with the company, Andrew took a master’s degree in Nuclear Science and Technology at the University of Manchester. As part of this, Andrew worked with Cerberus Nuclear on his master’s dissertation. His project focused on criticality calculations for a NWS transport package, for which some parameters would be varied in order to examine the sensitivity of the multiplication factor to these variations. This was in preparation for possible use in a future criticality transport toolkit.
Tu is a Criticality Safety and Radiation Shielding consultant at Cerberus Nuclear. He has been involved in a number of radiation shielding projects for a range of clients in the Nuclear Industry. Tu has supported the shielding design of a betatron training facility, a calibration facility and he has contributed significantly to the design of a remote retrievals and handling facility from early stage to detail design. He is experienced in using MCNP, SCALE and MicroShield for radiation shielding calculations. In criticality safety, Tu is experienced in generating handbook curves for nuclear facilities and has participated in the development of hazard management strategies for the geological disposal facility. Tu has also engaged in feasibility studies for digital safety cases. Before joining Cerberus Nuclear, Tu completed a PhD on nuclear safety, regulation and digital transformation for fission and fusion powerplants. He participated in the STEP program at UKAEA, completed reactor operation training at the Tsing Hua Open-pool Reactor in Taiwan, and holds an MSc in Physics and Technology of Nuclear Reactors from the University of Birmingham.
Nick, an Assessor on the Radiation Shielding team at Cerberus Nuclear, holds an MSc in Nuclear Science and Technology. He brings extensive experience in the field, including gamma spectrometry, both in the UK and Germany. In his current role at the company, Nick has worked on a wide range of projects in the radiation shielding team. Nick has worked on the optimisation of bulk shielding for a Betatron testing facility as well as the assessment of an X-Ray irradiator design, the shield door design for neutron and gamma cells for the AWE Hub Project and detailed design elements of the Remote Retrieval and Handling Facility at Rutherford Appleton Laboratory. His experience includes the use of radiation transport codes MCNP and SCALE. Nick also has experience in working on innovation projects, such as creating a digital twin for monitoring of changes to shape and size of nuclear storage vessels and the development of new shielding materials.
Sarah is a Criticality Consultant with three years prior experience in criticality safety and a further two years of safety case experience supporting waste treatment projects for civil nuclear clients. She has produced criticality hazard assessments for DSRL/NRS, EDF Cyclife and Urenco UK and has experience of using handbook data to provide criticality advice for various clients. Sarah has participated in HAZOPs both as a criticality specialist and in the secretary role. In addition to her criticality role, Sarah supports upkeep of Cerberus Nuclear's business through roles in project management, maintaining the company ISO accreditation and as a Security Controller. Prior to joining the nuclear industry, Sarah completed a PhD in Nuclear Materials Science and has experience of laboratory and synchrotron characterisation of uranium, thorium and technetium compounds.
Lisa Shenton is a Business Administrator at Cerberus Nuclear. She provides invaluable support to the Cerberus Nuclear management team and consultants. Her role is varied and includes supporting the business in finance, commercial, marketing and bid management. She is also responsible for invoicing, and will be in regular contact with our clients.
Zachary is a Radiation Shielding Consultant with an MSc in Physics and Technology of Nuclear Reactors. He has experience managing projects as well as providing radiation shielding support for clients such as AWE, BAE Systems, NUVIA, and Urenco, completing various shielding assessments during his time at Cerberus Nuclear. He has completed training in the use of radiation transport codes such as MCNP, SCALE, OpenMC, PHITS, FLUKA, and MCBEND. Zachary also has experience carrying out shielding verification and critical examinations of nuclear facilities using sealed source and X-ray devices.
Nathan is a Radiation Shielding Consultant with over 3 years of experience supporting Radiation Shielding and Characterisation projects at Cerberus Nuclear. While working at Cerberus Nuclear Nathan has completed Shielding assessments for clients such as AWE, Urenco, Sellafield and Nuvia. He’s completed Dose Uptake assessments, participated in HAZOPs, worked on innovation projects such as the Sellafield MSSS Characterisation robot and carried out internal QA. His calculation experience includes the use of MCNP, SCALE, ADVANTG, and OpenMC. He has also been involved in site visits to carry out Shielding Verification tests for the B3Ts project, and MOD sites. Nathan also currently leads the company’s internal Radiation Shielding training program and fulfils the role of Security Controller in addition to his consultancy work.
Haleema is a Criticality Consultant with an MSc in Nuclear Decommissioning and Waste Management and BSc in Physics. Haleema has been completing project work for the Safety Case Team at UUK, including a criticality transport assessment, MCNP Validation, Handbook Curve Generation, Criticality Memorandums, Notes for the Record, QA and a CWS Omission Case. She has built complex models and run calculations in MCNP of nuclear waste storage, such as ponds and bunkers. She has calculation experience in MCNP, MONK, MCBEND and SCALE. Additionally, Haleema is an active member of the SRP Magazine Editorial team, with a diverse skillset from her role as the Cerberus Nuclear Office Manager, and her previous experience in the Aviation Industry.
John Billingsley is a radiation shielding specialist with more than 6 years’ experience in the nuclear industry. Since joining Cerberus Nuclear in 2021, he has led the delivery of shielding and activation assessments for a wide range of high-profile projects spanning civil nuclear, defence, decommissioning, waste management, fusion, high-energy facilities, and new build programmes.
John has a broad technical capability and experience across shielding design, material activation, criticality dose consequence assessment, and CWS placement. He is an advanced user of radiation transport codes, including MCNP, OpenMC, SCALE, and PHITS, and is experienced in Python-based workflows, software development, and collaborative working practices.
John is currently the Secretary of The Shielding Forum and is an active member of the nuclear professional community, having presented at multiple international conferences, contributed to notable open-source neutronics projects, and delivered postgraduate training through the EPSRC Fusion CDT and NTEC programmes.
Katrina is a Criticality Assessor with over five years’ experience in the nuclear industry. She has contributed to a wide range of projects, from new build to decommissioning, for clients including AWE, UUK, UNS and NWS. Her experience includes fulfilling a technical criticality lead role, authoring HAZANs and PSR documents, chairing optioneering studies and attending HAZIDs and HAZOPs as a criticality specialist.
Katrina is highly skilled in the use of criticality codes for calculations, with particular expertise in MONK and MCNP, as well as the MCNP validation tool Whisper, applied on client projects. She has completed the Los Alamos Criticality Calculations Training Course for MCNP. In addition, Katrina has worked as part of integrated project safety teams, providing criticality support and safety assessments, and has been involved in fault analysis, collaborating closely with key stakeholders.
Alongside her consultancy roles, Katrina previously served as secretary for the Working Party on Criticality (WPC), where she actively supported the group by producing meeting agendas and minutes and managing WPC papers. Katrina also contributes to in-house development work, including Cerberus Nuclear’s criticality safety VR training aid, CARTA, and played an active role in recruitment, graduate training sessions, and student project supervision.
Sam Hilton is a radiation shielding consultant with over six years’ experience delivering shielding assessments across medical, commercial nuclear, fusion, and defence sectors, from concept design through to commissioning verification. His experience includes detailed design, transport, beamlines, target activation, source term generation and dose uptake calculations. Sam is highly proficient in Monte Carlo codes including MCNP, PHITS, OpenMC, FLUKA, and SCALE, with strong capability in data processing for shielding optimisation and advanced visualisation of dose information.
Sam recently managed the shielding design for the planning and construction of an AWE new build facility. He provided shielding expertise during HAZOP and design meetings while coordinating the team to deliver multiple assessments in line with the shielding design process. These assessments covered bulk shielding, penetration and door design for several highly intense X-Ray generators and Alpha‑Neutron sources. This project required design of bespoke shielding solutions that accommodated complex geometry and operational criteria in both gamma and neutron radiation environments.
