Full-Time

Senior Mechanical Engineer

ASSYSTEM

ASSYSTEM

5,001-10,000 employees

Engineering services for design, construction, commissioning

No salary listed

Derby, UK

Hybrid

Hybrid role: 1-2 days remote per week.

UK Top Secret Clearance Required

Category
Mechanical Engineering

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Requirements
  • Industry Experience: Previous work in nuclear, thermal power, oil and gas, or other regulated sectors. Experienced with steam turbines, condensers, feedwater heaters, pumps, and piping systems.
  • Thermal Power Expertise: Strong background in thermal power systems, with experience from FEED to detailed design and EPC delivery.
  • Procurement Skills: Skilled in developing procurement specifications and collaborating with equipment suppliers.
  • Technical Proficiency: Extensive technical experience in thermal power or similar projects.
  • Communication: Excellent at engaging with internal and external stakeholders.
  • Project Management: Capable of identifying and managing critical interfaces on major projects.
  • Safety Knowledge: Proficient in UK Health and Safety regulations, safety systems, HAZOP, and engineering standards.
  • Codes & Standards: Knowledgeable in ASME, European, and UK codes and standards.
  • Educational Background: Bachelor’s degree or Higher National Diploma in engineering.
  • Professional Registration: CEng or working towards it.
  • Security Clearance: SC Clearance or ability to achieve it.
Responsibilities
  • Intelligent Customer Role: Ensure supplier deliverables meet requirements by critically assessing designs.
  • Develop & Review Designs: Create and review Process Flow Diagrams, Piping and Instrumentation Diagrams, Layout Drawings, Sizing Calculations, Datasheets, and Specifications.
  • Conduct Optioneering: Lead and review optioneering studies, Decision Record Files, Design Descriptions, and Requirement Specifications.
  • Apply Systems Engineering: Develop and review Functional and Design Requirements using Systems Engineering principles.
  • Integrate Turbine Island: Seamlessly integrate Turbine Island design into the wider power plant.
  • Provide Technical Support: Serve as the technical contact for Turbine Island interfaces and stakeholder activities.
  • Support Design Reviews: Participate in Design Reviews and HAZID/HAZOP studies with multidisciplinary teams.
  • Liaise on Safety: Work with the safety team on nuclear safety licensing, environmental planning/permitting, and related activities.
  • Ensure Compliance: Adhere to statutory H&S policies, project quality, and the Quality Management System.
Desired Qualifications
  • Systems Engineering: Experience or awareness in Systems Engineering is a plus.

Assystem provides engineering services for complex projects, covering design, construction, supervision, commissioning, and operation, with a strong focus on the nuclear and energy sectors. Its approach combines multidisciplinary engineering teams and project-management capabilities to move projects from initial concept through to operation. The company differentiates itself through a long track record, strategic acquisitions (including Alphatem in 1995 and Mactech Energy Group in 2025) and an early public offering in 2013, which have expanded its capabilities and market reach in the energy and nuclear fields. Its goal is to be a leading, reliable partner for clients by delivering end-to-end engineering services and helping them meet safety, performance, and regulatory requirements across the project lifecycle.

Company Size

5,001-10,000

Company Stage

IPO

Headquarters

Paris, France

Founded

1966

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Simplify Jobs

Simplify's Take

What believers are saying

  • H1 2026 nuclear revenue grew 8.0% organically and reached 81% of total revenue.
  • French revenue rose 4.2% organically to €201.1 million, driven by nuclear new-builds.
  • UK civil nuclear engineering, defence, and government frameworks expand its addressable pipeline.

What critics are saying

  • Heavy nuclear concentration exposes Assystem to French or UK project delays and cancellations.
  • International volumes fell in India and the Middle East from project endings and slower phasing.
  • Currency weakness in sterling, rupee, and riyal continues to pressure reported growth.

What makes ASSYSTEM unique

  • Founded in 1966, Assystem specializes in nuclear engineering and project lifecycle services.
  • Its France business supports EDF across commissioning, new-builds, fuel cycle, and operations.
  • The 2025 Mactech Energy Group acquisition deepens its nuclear delivery capabilities.

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Benefits

Health Insurance

Dental Insurance

Vision Insurance

Unlimited Paid Time Off

Flexible Work Hours

Remote Work Options

Paid Vacation

Paid Holidays

Hybrid Work Options

401(k) Retirement Plan

Wellness Program

Mental Health Support

Gym Membership

Professional Development Budget

Conference Attendance Budget

Stock Options

Company Equity

Phone/Internet Stipend

Home Office Stipend

Relocation Assistance

Childcare Support

Meal Benefits

Parental Leave

Family Planning Benefits

Fertility Treatment Support

Company News

Bdaily
Jan 30th, 2025
Assystem expands UK footprint with takeover

A global nuclear engineering firm has strengthened its UK presence with the acquisition of a specialist construction company. Paris-headquartered Assystem has… | North East | Construction | Engineering | International | Energy | Mergers & Acquisitions | Commercial Partnerships | Manufacturing & Construction |

Assystem
Jan 17th, 2024
Assystem acquires KEOPS Automation, engineering specialist in automated systems and data enhancement

Assystem, an international engineering, digital services and project management company, has acquired 100% of the shares of KEOPS Automation, a French company specializing in the integration of industrial operating platforms and the enhancement of their data (industrial OT and IT, automated systems, supervision systems, BI applied to manufacturing).

Global Construction Review
Jan 5th, 2024
France’s Assystem acquires India’s L&T Infrastructure Engineering - Global Construction Review

France-headquartered engineer and project manager Assystem has acquired India’s L&T Infrastructure Engineering, a subsidiary of the Larsen & Toubro group.

Tech.eu
Feb 11th, 2022
Germany’s SQS acquired by Assystem Technologies for over Ā£280 million

German company Software Quality Systems (SQS), a provider digital quality assurance services,…