Executive Team

Julianne became Chief Executive Officer of UKNNL in April 2025, bringing over 25 years of nuclear sector experience to the role. 

After beginning her career as a Graduate Radiation Protection Advisor with British Nuclear Fuels Ltd, UKNNL's predecessor organisation, Julianne went on to hold strategic leadership positions at Nuvia, Atkins and PA Consulting before returning as our CEO. 

Julianne’s expertise lies in strategic implementation and operational excellence. During her career she has led and implemented transformational growth strategies, established strategic joint ventures between UK, European and international organisations and secured long term strategic frameworks with Government and commercial entities. As Global Head of Nuclear at PA Consulting, Julianne established and grew an innovative nuclear practice, working with clients across the entire nuclear fuel cycle from new build to decommissioning. 

Passionate about diversity and inclusion, Julianne has been a driving force for women in STEM. Her contributions to the nuclear sector were recognised with an Honorary Fellowship from the Nuclear Institute in 2023 and the National STEM Ambassador Award from Forward Ladies. 

Julianne holds an MSc in Pollution and Environmental Control from the University of Manchester and a BSc (Hons) in Environmental Science from Manchester Metropolitan University. 

In her spare time Julianne enjoys being in the great outdoors with her family, from skiing and cycling to running and walking, with most big days out finishing with a refreshing glass of something cold and fizzy! 

Dr Gareth Headdock is Chief Science and Technology Officer at the United Kingdom National Nuclear Laboratory. Prior to this, he was VP for Government and New Build - in this role, Gareth worked with government to identify how UKNNL can support the delivery of national-important programmes of nuclear research such as the recent Advanced Fuel Cycle Programme – a £56m BEIS-funded programme led by UKNNL in collaboration with over 100 other organisations.

Gareth joined UKNNL in 2018 as Science and Technology Director – a position which he held until taking up his current role in 2021. Prior to joining UKNNL, he worked for 12 years at Johnson Matthey, latterly in the role of Research and Development Director, where he managed research groups in the UK, Europe and the US. Gareth is also a Partner Director at the Henry Royce Institute.

Responsible for delivering safe, sustainable and cost-effective operations across all UKNNL sites, Oli became UKNNL’s Chief Operations Officer in 2024.

A key member of the Executive Team, he applies a decade of experience in delivering nuclear operations to ensure performance excellence and efficiency throughout all of UKNNL’s work.

Well-versed in the requirements of nuclear license conditions and regulations, and having led work to build, test and commission nuclear submarines, he has a strong track record of delivery. As an Executive Partner at IBM, Oli gained extensive experience in balancing the complex needs of customers while leading and motivating a team of highly talented technical specialists to consistently exceed customer expectations. And during his time at Alexander Dennis, and BMW MINI, Oli gained a reputation for delivering innovation in engineering, exceeding delivery targets, driving improvements and generating significant business value.

He also has prodigious enthusiasm for growing niche and specialist skills for the sector, demonstrated through the creation of a specialist skills academy at BAE and being a champion for building long lasting business relationships.

In his spare time, Oli enjoys open water swimming.

Des joined UKNNL in 1995 as a technical specialist and during this period has undertaken a wide range of senior leadership roles including Laboratory Manager, Business Leader and Head of Capability before taking on his current position as Vice President Nuclear Authority within the Executive Leadership Team.

With over 25 years’ experience in the nuclear industry, and having also been part of the BNFL journey, Des’s experience ranges from direct contribution as a technical specialist to nuclear facility management, technical capability leadership and strategy development.

Des is a Fellow of the Royal Society of Chemistry with a PhD in chemistry from the University of Newcastle upon Tyne

Des is responsible for ensuring UKNNL maintains priority and focus on Nuclear Safety and Security, providing Independent Assurance to the Executive and the Board.

Rebecca became UKNNL's Chief Human Resources Officer in February 2025, bringing over 20 years of experience in strategic HR leadership across both public and private sectors.

As part of our Executive Team, she applies her broad expertise in organisational transformation and people strategies to drive UKNNL's ambition of being an employer of choice in the nuclear sector.

Having already led significant change programmes at UKNNL since joining in 2018, Rebecca has demonstrated excellence in modernising HR operations and strengthening industrial relations. During her time at Rolls-Royce, PA Consulting and BAE Systems, she built a strong track record in delivering complex transformation projects, including managing multi-million pound change initiatives and developing innovative people solutions across global operations.

As a Fellow of the Chartered Institute of Personnel and Development, Rebecca brings valuable expertise in workforce effectiveness and strategic HR leadership. Her experience in unionised environments and track record of building collaborative relationships with Trade Unions has been particularly valuable in transforming UKNNL's employee relations landscape.

Outside of work Rebecca’s interests include travelling, music, reading and art.

Matt joined UKNNL in June 2018 and was appointed Chief Financial Officer in April 2019. He joined us from BAE Systems where he had spent the previous 16 years in a wide variety of roles, leaving his position as Finance Director for the Dreadnought Submarine Programme to join UKNNL.

Matt worked across multiple businesses within BAE Systems where he developed a deep understanding of financial management, corporate governance and information management and technology.

Matt is a Fellow of the Chartered Institute of Management Accountants and sits as a member of the CIMA Benevolent Fund. Outside work, he is a qualified rugby league coach with Chorley Panthers.

With more than 35 years’ experience in the nuclear industry, Nick’s expansive network and deep insight are especially valuable in his role as Special Advisor to the CEO.

He has previously served UKNNL and our executive leadership team as Chief Customer Officer, Finance Director, and Director Health & Nuclear Medicine and Space, driving forward our research at the cutting edge of nuclear science.

Nick was instrumental in setting up UKNNL’s waste management and decommissioning directorate, a cornerstone of our work. He also pioneered our Technical Services Agreement with Sellafield Ltd – Enhancing the work to decommission and safely clean up the Sellafield site securely, cost effectively and in ways that protect people and the environment.

With a record of innovation throughout his career, Nick served as an assessor and panel member for Innovate UK, helping businesses bring new products and processes to life.

Nick has a keen interest in geology, and his passion for dinosaurs was rewarded when one was named after him – the Dracoraptor hanigani. He holds a biochemical engineering degree and is a Fellow of the Institute of Chemical Engineers and a previous member of the board of the British Geological Survey.

As Chief Strategy Officer, Emma oversees UKNNL’s engagement with government, industry leaders and academia, exploring how we can work together to address society’s great challenges through nuclear science.

After joining UKNNL as VP Strategy, Emma led on the development of our corporate strategy and managing our relationship with government, keeping nuclear on the map through four changes of administration and a General Election.

An innovative and committed leader, Emma supported the development of UKNNL’s value framework, which guides how we operate and how we engage throughout the nuclear sector. This relentless focus on the standards we expect at UKNNL, aligned to our purpose and what our partners expect from us, has hugely enhanced our ability to engage effectively and our potential to influence policy.

With a degree and PhD in aeronautical engineering, Emma began her career at Atkins where she worked on nuclear projects, before moving on to the University of Nottingham where engagement and corporate strategy became an increasingly important part of her skillset.

Subsequent senior strategic roles at the Energy Research Accelerator and Nuclear Advanced Manufacturing Research Centre mean Emma is well-placed to guide UKNNL’s strategic function through an ever-changing nuclear landscape.

Leveraging his knowledge and relationships across the nuclear sector, James ensures a seamless experience and mutually beneficial relationship between UKNNL and our customers.

As Chief Customer Officer, James is responsible for identifying, securing and delivering our world-leading nuclear research and development programmes to our customers and partners across the UK and around the world.

He joined UKNNL as Chief Strategy Officer in 2017, leading the Strategy, Communications & Corporate Affairs directorate, a multi-disciplinary team responsible for defining and delivering how UKNNL fully realises its purpose of using ‘nuclear science to benefit society’. He became CCO in October 2024.

James has worked across a number of business sectors including management consultancy, tech, defence and national security, and the media, much of it internationally and often in roles that required effective stakeholder management in complex, dynamic and politically sensitive environments.

In addition to his responsibilities as CCO, James is also the executive sponsor for UKNNL’s sustainability agenda, in support of which he completed a Masters degree in Sustainability Leadership at the University of Cambridge. James also sits on the Strategic Advisory Committee of the Idaho National Laboratory in the US.