About Fuse

We are building one of the most potentially consequential companies of the century. Our mission is to accelerate the world's transition to fusion energy while safeguarding humankind. This is not a normal company. This is not a normal job. We are committed for the long term to win.

About the Role

You are the lead Health Physicist on site, responsible for the technical radiation-protection program: source terms, shielding, instrumentation, dosimetry, surveys, and the operational decisions that flow from them. This is a hands-on lead role.

Core Responsibilities

• Independently verify shielding designs developed by physics and engineering — geometry, source definition, tally choice, variance reduction, and uncertainty. Catch the errors before the concrete is poured.

• Run MCNP, PHITS, or GEANT4 transport calculations for the fusion generators, target chambers, beamlines, diagnostic ports, and shielded penetrations.

• Build and maintain validated source-term models: D-T neutron yield and spectrum, capture and inelastic gammas, bremsstrahlung, and characteristic line emission.

• Perform activation analysis on hardware in the neutron field and produce contact dose-rate vs. cool-down curves that operations can plan around.

• Dosimetry & Instrumentation

• Specify the radiological instrument fleet from first principles. Match detector physics to field characteristics: pulsed vs. continuous response, neutron energy range, photon discrimination, deadtime behavior, and true dose-equivalent response across the spectrum we produce.

• Select personal dosimetry technology appropriate for mixed neutron/photon fields and tritium-intake monitoring.

• Be responsible for the calibration program for high-end instruments to a standard that survives regulator review.

• Operational Release & Clearance

• Be the technical authority on whether hardware and areas are safe to touch or enter. Survey activated and potentially contaminated hardware, evaluate against release criteria, and document the basis.

• Develop and be responsible for activation-based clearance procedures: wait times, dominant nuclides over time, allowable contact handling, and packaging for off-site transfers.

• Conduct radiological surveys before, during, and after non-routine operations.

• Author radiological work permits with credible dose estimates derived from your own field characterization.

• Partnership with the Team

• Sit in design reviews with physicists and engineers from the start, not at the end.

• Partner with the RSO: you produce the technical basis; they translate it into licensed scope, procedures, and regulatory submissions.

• Train operators, engineers, and physicists on what their dosimeters and area monitors are actually telling them, including their limitations.

Minimum Qualifications

• Master's degree in Health Physics, Nuclear Engineering, Radiological Sciences, Physics, or a related field.

• Certification by the American Board of Health Physics (CHP). Fuse will support maintenance of certification status.

• 5+ years of operational health physics experience in environments with non-trivial neutron and photon fields, with at least 2 years in a tritium-handling environment.

• Demonstrated production-grade proficiency with at least one major transport code: MCNP, MCNPX, PHITS, GEANT4, or FLUKA.

• Working knowledge of 10 CFR 835 or 10 CFR 20, DOE-STD-1098, DOE-HDBK-1129, and 20.3 NMAC.

• Hands-on experience with tritium bioassay programs, internal-dose assessment, and ICRP biokinetic models for HTO.

• Experience leading activation analysis and authoring defensible "safe to handle" decisions on activated hardware.

Preferred Qualifications

• Experience with pulsed radiation sources such as DPF, Z-pinch, ICF drivers, or pulsed accelerators and the dosimetry challenges they create.

• Prior role specifying or commissioning a radiation-instrument fleet for a new facility.

• Track record partnering with R&D physicists and engineers as a working collaborator, not a downstream reviewer.

• Prior responsibility for DoD/DOE environmental monitoring programs and safety protocols.

• Experience integrating radiation controls with non-radiological hazards including HV, vacuum, cryogenics, and lasers, and with broader EHS systems.

• Familiarity with PDM/PLM and document-control practices, including change control for procedures and drawings.

What We Value

• Give a shit. Build things you're proud of.

• Take responsibility. If something is broken and you can fix it, fix it. See things through.

• Move fast. Make decisions, learn quickly, and keep moving forward.

• Think bigger. Simplify relentlessly. Don't default to the safe answer.

• Disagree and commit. The best idea wins. Once a decision is made, we move.

• Desire to win. This is hard. Expect intensity. We are here to win.

• Plan B is to make Plan A work.

Additional Requirements

• This is not a remote position and will require relocation if not already local to the applicable Fuse facility.

• Security Clearance

• This role may require the ability to obtain and maintain a U.S. government security clearance.

Benefits

• Medical, dental, and vision coverage.

• Relocation assistance for roles that require it.

• Flexible time off. Take what you need, no accrual tracking.

• 2 weeks of paid time off built into the end of each year, subject to team and business needs.

• Supportive leave of absence policies.

• Paid leave for new parents.

ITAR Requirements

To conform to U.S. Government technology export regulations, including the International Traffic in Arms Regulations (ITAR), you must be a U.S. citizen, lawful permanent resident of the U.S., protected individual as defined by 8 U.S.C. 1324b(a)(3), or eligible to obtain the required authorizations from the U.S. Department of State.

Equal Opportunity

Fuse is an Equal Opportunity Employer; employment with Fuse is governed on the basis of merit, competence, and qualifications and will not be influenced by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, ancestry, immigration status, sexual orientation, gender identity, marital status, mental or physical disability, or any other legally protected status.