Senior Mechanical Engineer

weServed; United Kingdom; Hybrid; GBP 100,000 - 125,000; Full time

Job summary

A leading nuclear engineering firm is seeking a Senior Mechanical Engineer to join their team in Harwell, Oxfordshire with hybrid working arrangements. The role involves leading design and delivering innovative solutions for critical nuclear decommissioning projects. Candidates should hold an engineering degree with significant experience in trials and detailed design. This position offers attractive compensation and a comprehensive benefits package including generous leave, pension schemes, and various development opportunities.

Benefits

Generous holiday allowance

Matched contribution pension scheme

Access to a Digital GP

Employee share scheme

Employee shopping savings portal

Payment of Professional Fees

‘Be Kind Day’ for volunteering

Holiday Trading opportunities

Qualifications

• Significant demonstrable experience in mechanical engineering.
• Ability to achieve and maintain Security Clearance (BPSS/SC).

Responsibilities

• Lead and support plant and equipment trial activities.
• Contribute to design reviews and ensure project coordination.
• Prepare and produce drawings for design in line with ISO standards.
• Provide technical assistance to the team.
• Resolve technical and delivery issues.

Skills

Practical experience in plant or laboratory trials

Detailed design for manufacture experience

Education

Engineering degree (or equivalent) in a relevant discipline

Job description

Job Title: Senior Mechanical Engineer

Location: Harwell, Oxfordshire + Hybrid Working Arrangements

Compensation: Attractive Salary + Benefits

Role Type: Full time / Permanent

Shape the Future of Nuclear Innovation

At Cavendish Nuclear we're working to create a safe and secure world, together, and if you join us, you can play your part as a Senior Mechanical Engineer at Harwell, near Didcot, Oxfordshire.

The role

As a Senior Mechanical Engineer, you'll have a role that is out of the ordinary. You'll be at the fore‑ground of designing and delivering innovative solutions for one of the UK's most critical nuclear decommissioning projects. Your work will directly contribute to the safe clean out of legacy waste storage facilities, paving the way for future building decommissioning.

Day to day, you will

• Lead and support plant and equipment trial activities, recommending and reviewing design updates.
• Contribute to design reviews and ensure coordination and functionality across projects.
• Prepare and produce drawings for basic, detail, and production design in line with ISO standards.
• Provide technical assistance and guidance to the wider Cavendish Nuclear team.
• Resolve technical and delivery issues, keeping project managers fully informed.

You’ll work 37 hours per week, Monday to Friday, based at Harwell, Oxfordshire. Hybrid working patterns are available (three days on site, two days remote).

Essential experience of the Senior Mechanical Engineer

• Practical experience in plant or laboratory trials, including writing and implementing Risk Assessments and Method Statements.
• Detailed design for manufacture experience.

Qualifications for the Senior Mechanical Engineer

• Engineering degree (or equivalent) in a relevant discipline, with significant demonstrable experience.

Security Clearance

The successful candidate must be able to achieve and maintain Standard (BPSS) / Security Check (SC) security clearance for this role. Further details are available at United Kingdom Security Vetting: clearance levels – GOV.UK ().

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 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: 17/12/2025