Senior Principal Mechanical Engineer

Our Vacancy
** Senior Principal Mechanical Engineer
*** Nuclear* Permanent /
* Blackburn* United Kingdom
* 14/04/25
* On site
* Share  Assystem is a global leader committed to accelerating the energy transition. With 7,750 employees across 12 countries, we tackle the monumental task of switching to low-carbon energy. Our 55+ years of experience in highly regulated sectors ensure we deliver top-notch engineering, project management, and digital solutions.
** Job Description*
* ** Join the Fusion and Modular Nuclear Business Unit!
** Assystem has an exciting opportunity for a Senior Principal Mechanical Engineer to join our expanding Fusion and Modular Nuclear (FMN) business unit. As leaders in the design and development of new technologies, you will have the opportunity to work across multiple cutting-edge projects developing technical solutions making net-zero power generation a reality.
** 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, ensuring alignment with project specifications, technical standards, and operational needs.
* ** Management of Interfaces** – Coordinate effectively between engineering teams, suppliers, and stakeholders to ensure seamless integration of cooling water systems with other reactor components.
* ** Preparation of Technical Specifications** – Develop clear, detailed 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.
* Over 55 years in nuclear engineering.
* Ranked among the top 3 largest nuclear engineering companies.
* Attractive social benefits, including an engaging Employee Committee and holiday bonuses.
* Ongoing training with numerous career opportunities.
* 70% of our managers are promoted internally!
* Hybrid work: 1-2 days remote per week.
* Multi-Disciplinary Team Leadership – Skilled in managing and coordinating diverse engineering teams.
* Steam Cycle Modelling Oversight – Ability to define modelling outcomes and ensure accurate implementation.
* Project Budget & Lifecycle Planning – Experienced in budgeting and planning for full design life cycles.
* Cooling Water Equipment Expertise – Strong track record in designing and optimizing cooling water systems.
* Regulatory & Compliance Knowledge – Well-versed in ONR, Environment Agency, and HSE regulations.
* Requirements Capture Experience – Skilled in gathering and defining technical requirements.
* Systems Engineering Awareness – Strong understanding of integrated design principles.
* Subcontractor Management – Experienced in overseeing and coordinating subcontractors.
* Chartered Engineer (CEng) – Professional accreditation in a relevant discipline.
* Security Clearance Eligibility – Capable of obtaining SC clearance for secure projects.
* ** Excellent communication skills, written and oral**
* ** Strong leadership skills**
* ** Focus on delivering quality output to time and budget**
* ** Act with integrity and instils this in others**
* ** Has an appreciation of wider technical issues beyond own discipline** – Understands interdisciplinary challenges and their impact on projects.
* ** Ability to work with a high degree of independence, using their own initiative and self-motivation** – Proactive and capable of managing tasks autonomously.
* ** Confident in a multi-party,…