Full-Time

Director of Nuclear Engineering

Xcimer Energy

Xcimer Energy

51-200 employees

Develops inertial fusion power using laser

Compensation Overview

$220k - $260k/yr

+ Equity

No H1B Sponsorship

Denver, CO, USA

In Person

US Citizenship Required

Bachelor's, PhD

Category
Aerospace Engineering (1)

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Requirements
  • Advanced degree in Nuclear Engineering or closely related technical field; PhD strongly preferred.
  • 15+ years of experience in nuclear engineering, including senior technical leadership responsibilities.
  • Demonstrated experience building, mentoring, and leading high-performing technical teams.
  • Strong foundation in radiation physics, nuclear engineering fundamentals, and analytical methods.
  • Experience with deterministic and Monte Carlo neutron/photon transport methods.
  • Experience using nuclear engineering analysis tools such as MCNP, OpenMC, or equivalent software.
  • Experience planning and managing technical work, including schedules, budgets, and performance metrics.
  • Experience operating effectively within matrix organizations and multidisciplinary technical environments.
  • Excellent written and verbal communication skills with the ability to communicate complex technical concepts to both technical and non-technical audiences.
  • Must be a U.S. citizen or national, U.S. permanent resident (current Green Card holder), or lawfully admitted into the U.S. as a refugee or granted asylum.
Responsibilities
  • Build, lead, and grow the Nuclear Engineering Department, including hiring, onboarding, mentoring, and performance development of engineering staff.
  • Develop career paths and technical leadership pipelines for nuclear engineers while fostering a culture of technical rigor, collaboration, safety, and continuous improvement.
  • Establish, document, and maintain nuclear engineering standards, methods, and best practices across concept development, design, testing, and operations.
  • Define and maintain the nuclear design basis for Xcimer facilities and programs, ensuring assumptions, analyses, and requirements support performance, safety, and regulatory objectives.
  • Partner with Program Directors and Managers to ensure nuclear engineering activities are appropriately scoped, resourced, prioritized, and scheduled.
  • Identify nuclear engineering risks early and collaborate cross-functionally to develop and implement mitigation strategies.
  • Ensure disciplined execution of core nuclear engineering activities, including radiation transport and shielding analysis, activation analysis, source term definition, uncertainty analysis, and support for radiological safety and hazards analysis.
  • Collaborate closely with Systems Engineering, Facilities, Test, Operations, ES&H, and peer engineering departments to integrate nuclear engineering considerations into system architectures, facility designs, and operational procedures.
  • Define and execute a long-term roadmap for nuclear engineering capability growth, including external partnerships with national laboratories, academic institutions, and industry collaborators.
  • Represent Xcimer in technical forums and within the broader nuclear engineering community to build technical credibility and attract top-tier talent.
Desired Qualifications
  • Experience within fusion energy, high-radiation facilities, or other advanced energy systems.
  • Experience collaborating with national laboratories, universities, or large multi-institution technical programs.
  • Experience establishing engineering standards and improving technical rigor across organizations.
  • Publication record or recognized technical leadership within the nuclear engineering community.

Xcimer Energy develops inertial fusion energy technology aiming to generate fusion-powered electricity. Its system uses a 10+ megajoule KrF laser to ignite a hydrogen fusion target inside a HYLIFE-style liquid-wall chamber, which absorbs fusion energy and shields reactor walls for long life. The approach combines a high-energy laser, a consumable fusion target, and a liquid-wall chamber to pursue scalable, laser-driven inertial confinement fusion for power generation. The company’s goal is to make commercial fusion power a reality for utilities within the next decade.

Company Size

51-200

Company Stage

Series A

Total Funding

$117.8M

Headquarters

Denver, Colorado

Founded

2021

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Simplify Jobs

Simplify's Take

What believers are saying

  • DOE approved Athena on June 10, 2026, after reviewing Xcimer's 724-page roadmap.
  • Phoenix started operations June 3, 2026, inside Xcimer's 74,000-square-foot Denver facility.
  • Xcimer hired nearly 200 employees and plans to double headcount by 2027.

What critics are saying

  • Vulcan site selection remains unfinished, delaying the 2031 engineering-breakeven target.
  • KrF module scaling from Phoenix to 12 MJ demands unproven cost-down and reliability.
  • If Phoenix or Vulcan misses milestones, DOE support and fusion credibility collapse.

What makes Xcimer Energy unique

  • Phoenix validates KrF excimer lasers and SBS compression at fusion-relevant energies.
  • Xcimer pairs DOE-approved Athena design with HYLIFE liquid-wall chamber economics.
  • The company owns a vertically integrated path from Phoenix to Vulcan to Athena.

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Benefits

Health Insurance

Dental Insurance

Vision Insurance

Life Insurance

Disability Insurance

401(k) Company Match

Paid Vacation

Paid Sick Leave

Paid Holidays

Company Equity

Growth & Insights and Company News

Headcount

6 month growth

-3%

1 year growth

-5%

2 year growth

0%
Business Wire
Jun 10th, 2026
DOE approves Xcimer's fusion power plant design, clears path to commercial laser fusion

Xcimer Energy has secured US Department of Energy approval for its preconceptual design and technology roadmap for Athena, its fusion power plant architecture. The milestone, part of the DOE's Fusion Milestone Development Program, positions the Denver-based startup amongst frontrunners to commercialise fusion energy. Xcimer's 724-page submission detailed plant performance targets, economics, engineering requirements, safety analyses and development pathways. Athena integrates the company's proprietary excimer laser platform with target delivery, fusion chamber, tritium breeding and power generation systems designed for industrial scale. The approval follows Xcimer's launch of Phoenix, the world's largest privately owned laser system, at its 74,000-square-foot Denver facility. Founded in 2022, Xcimer is developing laser fusion technology targeting costs under $100 per joule with a chamber design requiring no first-wall replacement.

TechCrunch
Jun 3rd, 2026
World's largest privately owned laser switched on by fusion startup Xcimer Energy

Fusion startup Xcimer Energy has activated its Phoenix laser system, which the company claims is the world's largest privately owned laser. The system uses excimer amplification to generate over one kilojoule of energy through a 38-metre-long krypton-fluoride laser core. Xcimer's approach mirrors the National Ignition Facility, which in December 2022 demonstrated a controlled fusion reaction producing more power than required to ignite it. The company aims to improve upon this concept using more powerful, less complex lasers that compress fuel targets in nanoseconds rather than microseconds. Phoenix represents an early step towards a commercial fusion power plant, which Xcimer estimates would require lasers exceeding 12 megajoules. The company plans to complete a prototype by 2028 and build its first commercial-scale power plant in the mid-2030s.

Business Wire
May 12th, 2026
Xcimer Energy hires defence VP as fusion startup scales team to 400 amid $90M facility build

Xcimer Energy has hired Doug Kunzman as Vice President of Defence as the Denver-based fusion startup scales towards commercial operations. Kunzman brings extensive military and aerospace experience, including commanding US Navy warships and leading operations at Blue Origin and Astra. The company, which now employs nearly 200 people, plans to double its workforce over the next year to advance Vulcan, its next-generation laser fusion facility. Xcimer is developing excimer-laser architecture for scalable inertial fusion energy with applications in energy resilience and national security. Recent leadership additions include Brad Appel as Chief Engineer for Vulcan, previously CTO at Ursa Major and SpaceX; Justin Brynestad as Senior Vice President overseeing Vulcan programme execution; and Rachel Konrad as Senior Vice President of Strategic Communications. Founded in 2022, Xcimer has secured Department of Energy funding.

Business Wire
Jun 6th, 2024
Xcimer Raises $100 Million to Put Inertial Fusion Energy on Path to Commercialization

Xcimer Energy Inc. today announced that it has raised $100 million in Series A financing led by Hedosophia, with participation from investors includin

Yahoo Finance
Jun 5th, 2024
Xcimer Raises $100 Million to Put Inertial Fusion Energy on Path to Commercialization

DENVER, June 04, 2024--Xcimer Energy Inc. today announced that it has raised $100 million in Series A financing led by Hedosophia, with participation from investors including Breakthrough Energy Ventures, Lowercarbon Capital, Prelude Ventures, Emerson Collective, Gigascale Capital and Starlight Ventures. Xcimer will use this financing to establish a new facility in Denver, where it will build a prototype laser system including the world’s largest nonlinear optical pulse compression system to adv