Assystem Bristol, United Kingdom

Join the Fusion and Modular Nuclear (FMN) Business Unit as a Senior Principal Mechanical Engineer. Be part of a team designing and developing cutting-edge technologies to enable net-zero power generation across multiple projects.

OverviewAssystem is a global leader accelerating the energy transition with 7,750 employees across 12 countries. We deliver engineering, project management, and digital solutions in highly regulated sectors with 55+ years of experience.

Your mission

Lead and support the development of designs for the following systems: Personnel Airlocks, Main Equipment Access Hatch, Fuel Transfer Channel, Piping Penetrations, Electrical Penetrations, Specialist Nuclear Doors

Conduct DFMEA (Design Failure Mode and Effects Analysis) to identify and mitigate potential failure modes early in the design process

Perform HAZID (Hazard Identification Study) to assess and document risks across the system

Complete and maintain Human Factors Checklists to ensure ergonomics and usability are considered in design decisions

Update and manage the project’s Risk Register to track, evaluate, and mitigate emerging risks

Design Package Production in line with requirements — oversee the creation of comprehensive design packages aligned with project specifications, technical standards, and operational needs

Management of Interfaces — coordinate between engineering teams, suppliers, and stakeholders to ensure seamless integration of cooling water systems with other reactor components

Prepare Technical Specifications to guide procurement, fabrication, and installation of key cooling water system components

Collaborate with cross-functional teams, including both new and existing FTEs and secondees across engineering and project functions

Why join the community of Switchers?

Over 55 years in nuclear engineering

Ranked among the top 3 largest nuclear engineering companies

Attractive benefits, including an Employee Committee and holiday bonuses

Ongoing training with numerous career opportunities

70% of managers promoted internally

Hybrid work: 1-2 days remote per week

Qualifications

Multi-disciplinary team leadership — experience managing and coordinating diverse engineering teams

Steam cycle modelling oversight — ability to define modelling outcomes and ensure accurate implementation

Project budget and lifecycle planning — experience budgeting and planning for full design lifecycles

Cooling water equipment expertise — track record designing and optimizing cooling water systems

Regulatory and compliance knowledge — familiarity with ONR, Environment Agency, and HSE regulations

Requirements capture experience — skilled in gathering and defining technical requirements

Systems engineering awareness — understanding of integrated design principles

Subcontractor management — experience coordinating subcontractors

Chartered Engineer (CEng) — professional accreditation in a relevant discipline

Security clearance eligibility — able to obtain SC clearance for secure projects

Additional information

Excellent communication skills, written and oral

Strong leadership and focus on delivering quality on time and within budget

Integrity and ability to inspire others

Appreciation of wider technical issues beyond own discipline

Independent work style with initiative and self-motivation

Confident in a multi-party, multi-national environment

Ability to travel to Assystem offices and customer sites within the UK

Support major UK and international Nuclear Clients

Due to the nature of work, applicants may be required to meet residency criteria to attain a minimum level of UK security clearance if not already cleared to SC level.

We are committed to equal treatment of candidates and to fostering diversity. We believe that bringing together people with different backgrounds and perspectives is essential for innovative and impactful solutions. Your skills and talents are what matter. Bring your unique contributions and help shape the future.

Location notes may appear in job postings where applicable.

Location details: Bristol, England, United Kingdom

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