Senior Project Manager

At Amentum, we're not just solving problems; we're engineering the future. Our team is driven by an unyielding commitment to innovation, integrity, and collaboration, tackling some of the most significant challenges in science, security, and sustainability. If you're passionate about making a real impact and want to be part of a community that values ethical excellence, this is the place where your ambition can thrive.

Here, we believe that success comes from continuously pushing boundaries and working together to deliver on our promises. We embrace challenges with confidence and are dedicated to creating a secure and vibrant future for all.

We’ll inspire and empower you to deliver your best work so you can evolve, grow and succeed – today and into tomorrow. We offer an exciting range of opportunities to develop your career within a supportive team who always strive to do the right thing for our people, clients and communities.

People are our greatest asset, and we offer a competitive package to retain and attract the best talent.

In addition to the benefits you’d expect, UK employees also receive free single medical cover and digital GP service, family-friendly benefits such as enhanced parental leave pay and free membership of employee assistance and parental programmes, plus reimbursement towards relevant professional development and memberships.

Work‑life balance and flexibility is a key focus area for us. We’re happy to discuss hybrid, part‑time and flexible working hours, patterns and locations to suit you and our business.

Amentum is a Lot 1 delivery partner within the Decommissioning and Nuclear Waste Partners (DNWP) Framework, a major Sellafield programme worth up to £4.6 billion and running for up to 15 years. The framework is focused on safely accelerating decommissioning, remediation and high‑hazard risk reduction across one of the most complex nuclear sites in the world.

Our nuclear team supports the front‑end design, engineering, technical leadership and delivery expertise required across the DNWP portfolio. We are looking for individuals with high‑value expertise from across regulated and comparable sectors to who can work collaboratively, embrace new challenges and contribute to the mission of safely and efficiently delivering Sellafield’s decommissioning and nuclear waste objectives.

As a Senior Project Manager you will be responsible for planning, executing, and closing projects, ensuring they are completed on time, within budget, and meet stakeholder expectations.

You will conduct work alongside Delivery Leads, Package Managers, Engineers and with support from Administrators.

Employee will be expected to contribute to the delivery of social value in line with the DNWP framework, supporting positive outcomes for local communities. Voluntary engagement is supported, with up to 16 hours per full‑time equivalent allocated.

• Provide strategic leadership and oversight for multiple complex or high value projects, ensuring alignment with organisational objectives and client expectations.
• Take full accountability for end‑to‑end project delivery performance, including cost, schedule, quality, safety, and risk across assigned portfolios.
• Lead, mentor, and develop Project Managers and other delivery staff, providing professional guidance, performance management, and succession planning support.
• Act as the primary senior interface with clients, joint venture partners, regulators, and internal senior leadership, managing key relationships and escalation matters.
• Oversee the development, approval, and governance of project execution plans, ensuring consistent application of best practice project management methodologies.
• Provide assurance that robust project controls are in place, including programme management, cost control, risk and opportunity management, and change control processes.
• Review and challenge project budgets, forecasts, and schedules, ensuring early identification of risks, trends, and recovery actions where required.
• Sponsor and lead resolution of complex project issues, claims, disputes, and contractual matters, providing direction and support…