Job Description

The Head of SIXEP leads, directs and develops a complex sub-portfolio which may consist of a combination of operations, programme, projects and decommissioning activities to ensure safe and secure delivery to meet strategic performance outcomes, targets and realise benefits while reducing waste and maximising value for our stakeholders.

Authorities & Dimensions

The Head of SIXEP holds full accountability for the overall SIXEP programme and is formally appointed as its Senior Responsible Owner (SRO). This strategically significant role centres on complex programme leadership, business case development and the integration of multiple major capital projects within a £4–9 billion new capability programme. These include potential GMPP projects such as SIXEP Continuity, SIXEP Retrievals, and the SIXEP Waste Treatment Project, supported by a wider suite of enabling activities that collectively secure the site’s long‑term effluent treatment capability. While the SRO does not directly deliver these projects, the role provides strategic alignment, governance, assurance and sponsorship to ensure they collectively achieve the required programme outcomes and future operational capacity.

In parallel with this change portfolio, the postholder manages an annual programme budget of approximately £30 million. This demands rigorous prioritisation, robust financial governance and effective performance management to maintain safe, efficient and value‑driven delivery. The Head of SIXEP also leads a substantial organisational footprint, with accountability for up to 100 direct staff and a similar number indirectly through contractors and partnered delivery models. The role requires high‑quality engagement with executive, board‑level and government stakeholders, representing the programme externally, shaping strategic decisions and securing sustained long‑term support.

Alongside these programme responsibilities, the postholder holds full accountability for the safe, reliable and compliant operation of the existing SIXEP plant, ensuring ongoing operational performance while balancing day‑to‑day plant demands with the delivery of transformational future capability.

Principal Accountabilities

• Manage all activities within the business area to ensure agreed performance targets are met and nuclear safety remains an overriding priority.
• Responsible for the overall leadership and safe operation of facilities, programmes and projects to realise agreed programme and portfolio outcomes.
• Deliver and embed transformational improvements across the business area, promoting, stimulating, encouraging and leading change, sharing learning and best practice.
• Lead a continuous improvement culture within their area that is intolerant of waste and focused on acceleration in line with the programme and portfolio value proposition and agreed performance targets.
• Drive a similar focus and culture across the areas that support delivery, including enterprise functions, supporting the identification and removal of waste from their processes.
• Where required develop, set and communicate the performance requirements and measures in line with overall portfolio requirements and work collaboratively with supporting services and functions to align their measures to drive value.
• Support and deliver the COO cross cutting performance objectives. Working collaboratively across the portfolios and the enterprise operating model. Ensuring that decisions made support the long-term ambition of the organisation and do not adversely impact other portfolio’s and enterprise objectives.
• Understand and identify the commercial opportunities that exist to further improve area efficiency and effectiveness whilst also understanding the socioeconomic impact of their work and the associated aspects of the company strategy.

Role Context and Challenges

The Head of SIXEP is a senior leader who delivers value adding outcomes and benefits within a portfolio whilst maximising value for our stakeholders. They will drive safe and secure transformational change and continuous improvement whilst ensuring full alignment with the value stream and overall enterprise. This will require collaborative engagement, influence and behaviours across the portfolio and with other parts of the business (other portfolios and enterprise functions) to drive change and remove waste.

The incumbent requires a broad understanding of the business as well as an appreciation of nuclear safety, security and programme and project principles. For example, the incumbent must be able to scope and initiate studies, develop and communicate functional requirements for projects and operational delivery plans which realise the programme and portfolio benefits from the new capabilities delivered. This requires close collaboration with other portfolios, functions and services.

The role requires the incumbent to be commercially astute as some of the activities will require close collaboration with the supply chain where delivery models can be developed to drive innovation and improved value for money for the UK taxpayer. This may include understanding the value of the capabilities within their teams and the business development opportunities and socioeconomic aspects with the supply chain and wider community.

Within a portfolio and as a collective, they will take ownership and drive the required business behaviours and culture towards the creation of value and working collaboratively. To be successful, they need to work strongly together as all the portfolios and supporting functions have high interdependency. They must therefore avoid the creation of a polarised position that is too focused to their objectives and take a wider portfolio and enterprise perspective.

Knowledge & Experience

• A Degree level graduate/ or significant relevant experience within the Nuclear Industry.
• Significant leadership experience in a public or private sector organisation.
• Extensive experience of site operations capable of operating at a strategic level across the full business lifecycle. Ideally operating in complex, highly regulated, high hazard and uncertain delivery environments. With significant experience of the challenges of delivering complex change as well as continuous improvement projects.
• Extensive experience of risk management and pragmatic/effective mitigation strategies/implementation in a highly complex organisation.
• Lead and manage senior stakeholder relationships, internally and externally, with proven ability to build productive, diplomatic and beneficial relationships with external, internal and government partners and other key stakeholders.
• Role model and promote the required leadership and organisational behaviours.

Additional Information

• Open VN
• Number of Vacancies: 1
• Contact/s: Stuart Pearson

The date of the interviews for this position will be confirmed in due course.

If you choose to apply for this role and your application is shortlisted by the hiring manager, you will be invited to a competency based interview. In the interview, you will be assessed against the NDA Leadership Standard.

Sellafield Ltd are recognised as a Disability Confident Employer (Level 3). Disability Confident employers offer an interview to disabled applicants that meet the minimum criteria for a vacancy. Sellafield Ltd define the minimum criteria as the ‘essential skills’ which are listed on the vacancy notice. Whilst completing your application form, you will be able to indicate if you wish to be considered under the disability confident scheme. If you would prefer to discuss this directly with us, please contact the GBS Recruitment team on recruitment@sellafieldcloud.co.uk

Please ensure that you save a copy of this advert for future reference if you make an application for this role.

The closing date for this vacancy is Friday 20th February 2026.