Principal Nuclear Mechanical Engineer

Date: Oct 27, 2025

Location: Oak Ridge, TN, US, 37830

Company: Oak Ridge National Laboratory

Requisition Id 15526 

 

Overview:  

We are seeking a Principal Nuclear Mechanical Engineer to join the Systems Engineering (SE) Group within the Research Reactors Division (RRD) at Oak Ridge National Lab (ORNL). Our group is responsible for the High Flux Isotope Reactor (HFIR) configuration management program. The SE Group also provides technical support to operations and maintenance and performs systems analysis. In this role, you will perform expert level design engineering, and support manufacturing and fabrication of reactor core components, fuel elements, control rods and plates, etc. You will also handle maintaining overall cognizance of assigned HFIR structures, systems, and components (SSCs) and provide systems engineering support for operations and maintenance. 

 

Major Duties/Responsibilities: 

Configuration Management:

  • Provide technical authority for mechanical design and configuration of HFIR structures, systems, and components.
  • Oversee design, analysis, and documentation for upgrades and replacements to ensure compliance with safety and design bases.
  • Approve engineering work against applicable codes and standards (ASME, AWS, ASTM, ISO, etc.).
  • Lead development of long-term reactor component replacement and modernization plans.
  • Define design and material specifications for complex component upgrades and procurements.
  • Direct fabrication, assembly, and installation of core components and special tooling.
  • Ensure design changes meet configuration control requirements and maintain accurate as-built records.
  • Lead major mechanical modification projects from concept through implementation. 

 

Maintenence & Operations Support:

  • Provide expert consultation on system performance, maintenance strategy, and operational decisions.
  • Resolve complex equipment and system issues through technical analysis and corrective actions.
  • Guide preventive and predictive maintenance planning to sustain system reliability.  
  • Lead and manage programs under the ASME Boiler and Pressure Vessel (B&PV) Code such as Inservice Inspection/Inservice Testing (ISI/IST) program.
  • Provide technical support to HFIR Upgrade Projects office such as the HFIR Pressure Vessel Replacement project.

 

Systems Analysis & Reliability:

  • Lead system health and reliability assessments under the HFIR Reliability Program.
  • Identify performance trends, vulnerabilities, and priorities for long-range planning.
  • Oversee resolution of obsolescence and spare-part issues and mentor staff in reliability engineering methods.
  • Deliver ORNL’s mission by aligning behaviors, priorities, and interactions with our core values of Impact, Integrity, Teamwork, Safety, and Service. Promote equal opportunity by fostering a respectful workplace – in how we treat one another, work together, and measure success.

 

Basic Qualifications:

  • A BS in mechanical engineering related field and at least 20 years of proven experience. 
  • Advanced experience in project management, leading maintenance tasks, procedure development, procurement of materials and equipment analysis. 
  • Experience and thorough understanding of ASME vessel and piping codes. 

 

Preferred Qualifications:

  • Ability to diagnose mechanical equipment problems and develop formal work package instructions for performance and documentation of repairs. 
  •  A strong understanding of reading and interpreting mechanical design drawings as well as understanding of GD&T principles from ASME Y14.5. 
  •  Familiarity with mechanical design and maintenance activities in a nuclear reactor operating environment.   
  • Experience in operation and troubleshooting HVAC systems, and familiarity with the code on Nuclear and Gas Treatment ASME AG-1. 
  • Experience with cryogenics and working with cryogenic equipment. 
  • Strong thermodynamics background and experience. 
  • Familiarity with the regulatory programs which define the HFIR work environment, including DOE Orders pertaining to conduct of operation and maintenance, OSHA requirements.   

 

Special Requirements:

  • Physical Requirements: Work involves various physical requirements and working conditions. As such, a pre-hire physical will be required after offer.
  • L Clearance: This position requires the ability to obtain and maintain a clearance from the Department of Energy. As such, this position is a Workplace Substance Abuse (WSAP) testing designated position. WSAP positions require passing a pre-placement drug test and participation in an ongoing random drug testing program.

 

Benefits at ORNL:  

We offer competitive pay and benefits programs to attract and retain hardworking people! The laboratory offers many employee benefits, including medical and retirement plans and flexible work hours, to help you and your family live happy and healthy. Employee amenities such as on-site fitness, banking, and cafeteria facilities are also provided for convenience.

 

Other benefits include the following: Prescription Drug Plan, Dental Plan, Vision Plan, 401(k) Retirement Plan, Contributory Pension Plan, Life Insurance, Disability Benefits, Generous Vacation and Holidays, Parental Leave, Legal Insurance with Identity Theft Protection, Employee Assistance Plan, Flexible Spending Accounts, Health Savings Accounts, Wellness Programs, Educational Assistance, and Employee Discounts. Relocation Assistance is available for this position.

 

If you have difficulty using the online application system or need an accommodation to apply due to a disability, please email: ORNLRecruiting@ornl.gov.

 

#LI-LK1

 

This position will remain open for a minimum of 5 days after which it will close when a qualified candidate is identified and/or hired.

 

We accept Word (.doc, .docx), Adobe (unsecured .pdf), Rich Text Format (.rtf), and HTML (.htm, .html) up to 5MB in size. Resumes from third party vendors will not be accepted; these resumes will be deleted and the candidates submitted will not be considered for employment.

 

If you have trouble applying for a position, please email ORNLRecruiting@ornl.gov.

 

ORNL is an equal opportunity employer. All qualified applicants, including individuals with disabilities and protected veterans, are encouraged to apply.  UT-Battelle is an E-Verify employer.


Nearest Major Market: Knoxville