Blykalla is a Swedish deep-tech company at the forefront of the nuclear industry, pioneering the development of small modular reactors that provide clean, safe, and reliable energy. Thanks to lead-cooling, we achieve high safety in a very compact format, allowing for a simple and cost-effective design that can be mass-produced. Our unique reactor design will provide safe and green baseload energy that perfectly complements solar and wind power.
We're seeking a junior / mid-level Core Designer to join our Nuclear Engineering & Safety team in Stockholm. In this role, you will design and analyze fast reactor core configurations, optimize fuel loading patterns, and ensure safe, efficient, and economical operation of nuclear reactors throughout their fuel cycles.
Design and optimize reactor core variants for our cutting-edge lead-cooled fast reactor designs
Perform neutronic and burn-up analysis using industry-standard codes
Conduct safety analyses including shutdown margin, power peaking, and thermal-hydraulic evaluations
Develop and validate core design models and methodologies
Prepare technical documentation, design reports, and licensing submittals for regulatory review
Support transient and accident analyses to demonstrate compliance with safety limits
Stay current with advances in fuel designs, computational methods, and regulatory requirements
The core designer sits in the Nuclear engineering & safety team within Blykalla, and reports to the manager of Nuclear engineering & safety. We are a diverse team that is passionate about our work and our company.
You will be part of a highly skilled team with a can-do attitude. We value personal chemistry and strive to create a workplace where you enjoy coming to. There are however a few things that we think will help for you to succeed in this role, these are:
Master's degree in nuclear engineering, physics, or a related field
0-5 years of experience in reactor core design, reactor physics, or fuel management
Proficiency with Monte Carlo neutron transport codes (e.g. Serpent, MCNP) and experience setting up and running full-core or assembly-level models
Familiarity with the full core design workflow including cross-section generation, uncertainty propagation, depletion analysis and burnup-dependent reactivity feedback characterization
Strong understanding of reactor physics, thermal hydraulics, and fuel performance
Familiarity with regulatory frameworks (SSM, NRC, IAEA, or equivalent)
Excellent analytical, problem-solving, and technical writing skills
Fluency in English, spoken and written
Meritorious skills:
Experience with core design for PWR, BWR or advanced reactors
Programming skills in Python, Fortran, or MATLAB
Experience in methods development and/or verification & validation of computational tools
Experience in supporting licensing activities or in regulatory interaction
Fluency in Swedish, spoken and written
If you are not sure that you are 100% qualified, but are up to the challenge, we encourage you to apply.
Location
This position is for our office in Stockholm.
So, what do you think?
Joining our team means being part of a supportive and innovative environment where your ideas are valued and your expertise is recognized. You will have the opportunity to work with industry leaders and contribute to the safe and sustainable use of nuclear power.
If you are ready to take on this exciting challenge and play a pivotal role in nuclear safety, apply now and help shape the future of the nuclear energy industry!
Note: We encourage applicants from diverse backgrounds and are an equal-opportunity employer.
We do not accept applications via email.
We are not open to external help from recruitment agencies.

Blykalla is on a mission to change the energy future of the world, by providing green, safe, baseload energy through next generation small modular lead-cooled reactors.
Blykalla is a Swedish deep-tech company founded in 2013 by Janne Wallenius, Peter Szakalos and Jesper Ejenstam as a spin-off from the Royal Institute of Technology in Stockholm, where Janne Wallenius carried out research on design and safety analysis on lead-cooled reactor systems since 1996.
We develop and build lead-cooled small modular reactors (SMRs) to deliver safe, scalable and carbon-free baseload power supply. Thanks to lead-cooling, we achieve high safety in a very compact format, allowing for a simple and cost effective design that can be mass produced. Our unique reactor design will provide safe and green baseload energy that is a perfect complement to solar and wind power.