Mechanical Commissioning Engineer – Nuclear Systems

About Assystem

At Assystem, our mission is to accelerate the global energy transition. With over 7,500 Switchers worldwide, we combine engineering expertise, project management, and digital innovation to deliver major infrastructure programmes. In the UK, we're at the forefront of landmark projects including Hinkley Point C, Sizewell C, and future Small Modular Reactors (SMRs). By joining us, you'll be contributing to some of the most exciting and important engineering challenges of our time.

Why Join the Community of Switchers?

At Assystem, you'll be part of one of the top three largest nuclear engineering companies in the world. Joining us means working in a collaborative and supportive environment where innovation thrives. You'll be empowered to grow your skills while contributing to cutting-edge projects that have a lasting global impact.

Please note: Due to project security requirements, Unfortunately, visa sponsorship is not available for this position.

The Job Mission

This is a hybrid role, based in Bridgwater (Hinkley Point C). We can consider those within a commutable distance or open to relocation — with a relocation package available to support your move.

As a Mechanical Commissioning Engineer, you'll join the Nuclear Island team supporting key mechanical and process systems. Working with experienced leads, you'll take ownership of defined systems and support commissioning documentation, testing, and validation.

Key Responsibilities:

• Prepare commissioning documents and test procedures for assigned systems.
• Support readiness reviews and verify system pre-requisites are complete.
• Coordinate mechanical tests including flushing, leak tests, and pump runs.
• Analyse test results and produce clear, concise technical reports.
• Ensure all activities meet nuclear, environmental, and safety standards.
• Work with design and site teams to resolve technical issues quickly.
• Track system changes using approved configuration control processes.
• Support hazard identification and risk assessments for test activities.
• Participate in field execution of inspections and walk-downs.
• Build technical knowledge of assigned systems and plant operations.

Essential Skills and Qualifications

• Experience in mechanical commissioning, maintenance, or plant operations.
• Experience in regulated or heavy industrial environments.
• Familiarity with mechanical drawings and commissioning procedures.
• Ability to interpret data and write clear documentation.
• Degree, HNC, or equivalent in Mechanical Engineering.
• UK Nationals only – we cannot offer visa sponsorship.

Desired Skills

• Knowledge of pumps, valves, and process system testing.
• Understanding of CDM regulations and on-site safety.
• Experience in nuclear or process plant commissioning.
• Knowledge of fluid or radwaste system operations.
• Awareness of QA/QC processes and document control.
• Understanding of system turnover or handover procedures.
• Motivation to progress toward full system ownership.

Please note: Due to project security requirements, Unfortunately, visa sponsorship is not available for this position

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Why Apply?

This is your chance to work on a project that defines the future of clean energy in the UK. You'll join a forward-thinking organisation where your contribution directly supports a safer, more sustainable world. If you're ready to take on the challenge and grow with your future team, apply today.

Benefits include:

Hybrid Working Opportunity

Flexible working hours

Pension scheme (8% company contribution / 4% personal contribution)

25 days' paid annual leave + bank holidays + option to buy or sell days

Professional fees reimbursed

Employee referral scheme

Competitive Sick Pay – Support when you need it

Income Protection & 3x Salary Death-in-Service Cover

Free Digital Gym Access – Expert-led fitness classes

24/7 Employee Support Line – Mental health, financial & legal help

We are committed to equal treatment of candidates and promote, as well as foster all forms of diversity within our company. We believe that bringing together people with different backgrounds and perspectives is essential for creating innovative and impactful solutions. Skills, talent, and our people's ability to dare are the only things that matter . Bring your unique contributions and help us shape the future.