Job Description

Job Title: Principal Mechanical Engineer
Location: Whitehaven, Cumbria + Hybrid Working Arrangements
Compensation: Competitive + Benefits
Role Type: Full time / Permanent
Role ID: SF70329
Lead Engineering Excellence in Nuclear Decommissioning
At Cavendish Nuclear, we're working to create a safe and secure world, together. If you join us, you can play your part as a Principal Mechanical Engineer at either of our Westlake's Science Park, Moor Row or Warrington, Cheshire sites.
The role
As a Principal Mechanical Engineer, you'll play a pivotal role in one of the UK's major civil nuclear decommissioning programmes. Working as a senior technical authority within a multidisciplinary engineering environment, you'll drive the integration of complex mechanical systems and develop innovative solutions that directly support the safe deconstruction and long-term management of nuclear facilities.
You'll lead engineering teams, oversee high-integrity technical outputs, safeguard design quality, and act as a primary interface for customers-while mentoring engineers and championing continuous improvement across projects. This role places you at the technical forefront of a major expansion within the Cavendish Nuclear Design Services Alliance.
Day-to-day, you'll have the following responsibilities:

• Lead and manage multidisciplinary engineering teams to deliver high-quality technical solutions
• Supervise and mentor engineers and technical specialists to ensure performance and development
• Act as a key liaison with customers, ensuring transparent communication and technical clarity
• Oversee production, review, and approval of engineering outputs-including calculations, specifications, and reports
• Champion safety, quality, and engineering best practice across all project activities.

This is a full-time position working 37 hours, 5 days per week, based at either of our Westlake's Science Park, Moor Row or Warrington, Cheshire sites.
Essential experience of the Principal Mechanical Engineer:

• Extensive experience leading multidisciplinary engineering teams and delivering complex technical projects
• Proven ability to supervise and mentor engineers and technical specialists
• Strong background in producing, reviewing, and approving detailed engineering outputs
• Demonstrated expertise in applying procedures, codes, and standards to ensure compliance and integrity
• Track record of effective customer engagement, issue resolution, and technical support.

Qualifications for the Principal Mechanical Engineer:

• Engineering degree (or equivalent) in a relevant engineering discipline.

Security Clearance
The successful candidate must be able to achieve and maintain Standard (BPSS) security clearance for this role. Further details are available at
What we offer

• Generous holiday allowance
• Matched contribution pension scheme, with life assurance
• Access to a Digital GP, annual health check, and nutritional consultations through Aviva DigiCare+
• Employee share scheme
• Employee shopping savings portal
• Payment of Professional Fees
• Reservists in the armed forces receive 10-days special paid leave
• Holiday Trading is a benefit that allows UK Cavendish employees to buy additional leave or to sell up to one working week of annual leave from their annual entitlement. This Window opens February through to March annually.
• 'Be Kind Day' enables employees to take one working day's paid leave a year (or equivalent hours) to undertake volunteering work with their chosen organisation or registered charity
• Excellent development opportunities and benefits package including an employee assistance programme supporting physical, mental and financial wellbeing.

Cavendish Nuclear
As a leader within the UK nuclear industry, Cavendish Nuclear, part of Babcock International Group, provides a comprehensive range of critical nuclear solutions in clean energy, defence and civil new build and decommissioning projects. Together, we're innovating to make nuclear safer, faster and cost-effective across the nuclear energy life cycle. Your career with us could take you anywhere within Babcock International Group - from Canada, the USA to Japan. Work with us to create a safe and secure world, together.
We are a disability confident committed employer. If you have a disability or need any reasonable adjustments during the application and selection stages, please email with the subject header 'Reasonable adjustments requirement'. We're committed to building an inclusive culture where everyone's free to thrive. We are happy to talk about flexible working - please ask about alternative patterns of work at interview.
Closing date: 17/02/2026
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Skills Required