Mariam Thomas on returning to a STEM career and thriving in nuclear

Mariam Thomas is a project manager working within the energy sector who returned to the workforce with a clear sense of purpose and a wealth of transferable skills after a five-year career break to raise her children.

With a background in civil engineering and a Master’s in transportation systems engineering, Mariam began her career in the transport sector before stepping away to focus on family.

Her journey at Mott MacDonald has since seen her transition from transport to nuclear and from stay-at-home mum to project leader. Her career path is a powerful example of how non-linear journeys can lead to meaningful impact and lasting job satisfaction.

What was it like returning to work after a five-year career break?

It was exciting and daunting all at once. I was nervous but also thrilled at the thought of doing something more. I’d been a full-time mum to two young boys and, while I was fulfilled, I knew I had more to give professionally.

The biggest challenge initially for me was overcoming my own self-doubt. I used to see the gap on my CV as a weakness, but I’ve come to realise it was formative. That period gave me resilience, patience and perspective. I’ve learned these skills have been invaluable in my career.

How did Mott MacDonald support your return to work?

From day one, I was treated as someone with valuable experience, not just someone starting from scratch. My team included people who had also taken career breaks, which made me feel seen and understood.

My line manager once told me that the best project managers are mothers – probably due to our ability to juggle multiple things at once – and that stuck with me. I was never made to feel small for asking questions or needing flexibility. The culture here genuinely respects career journeys that don’t follow a straight line.

How did your experience in transport help you succeed in the nuclear sector?

My engineering experience in the transport sector laid a strong foundation for my transition into nuclear. Working as a civil engineer, I developed a systems-based mindset, always thinking about deliverables, risks, scope and timelines. That way of thinking is essential in nuclear, where precision and attention to detail are critical.

The structured approach I developed in transport helps me manage complex programmes with clarity and calm. Now, as a project manager, I use those same principles to bridge the gap between technical teams and client outcomes, ensuring delivery in a high-stakes, regulated environment.

How do you balance work and family life?

Balance is a constant recalibration. Some weeks, work needs more from me; other weeks, it’s my children. What makes it possible is the trust and flexibility I have at Mott MacDonald. I can do school drop-offs, manage appointments and still deliver on my projects. Work is flexible as long as the work gets done. That kind of trust is rare and I don’t take it for granted.

Why is it important to support and elevate women in nuclear?

Nuclear has historically been male-dominated and, while change is happening, it can feel slow. For that change to be meaningful, we need women in leadership, delivery and technical roles. Women bring different perspectives to safety, risk, innovation and collaboration – all of which are essential in this sector.

Supporting women isn’t just the right thing to do, it’s the smart thing to do. That’s why I’ve made it a priority to share my journey openly, especially my return to work after a significant career break, to show others what’s possible.

As deputy lead for women in project management at the Association for Project Management, I’m proud to help create inclusive spaces where women can thrive. I also mentor others, speak candidly about the realities of balancing motherhood and career and advocate for flexible working and inclusive policies. For me, this work is about more than representation, it’s about driving lasting change in a sector that needs diverse voices to grow and evolve.

What advice would you give to someone returning to work after a break?

Don’t underestimate your value. Whether your break was for family, mental health or a career change, the skills you’ve gained such as resilience, time management and patience are all valuable assets. Growth isn’t linear and that’s okay. It’s all about easing in gently, connecting with others and remembering that a community is powerful.

Why should someone consider Mott MacDonald to restart or grow their career in nuclear?

Mott MacDonald “walks the talk”. I’ve experienced first-hand how supportive, flexible and empowering the culture is. There’s room for ambition, but also space for humanity. I’ve never felt like I had to choose between being a good mum and a good employee. In nuclear, we’re working on accelerating a low carbon energy future. At Mott MacDonald, you don’t have to choose between making a difference and living a life; you get to do both.

Curious about where your skills could take you and ready to restart or grow your career in nuclear?

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