Lead Thermohydraulics Analyst - Nuclear Systems

Blykalla; Stockholms kommun; On-site; SEK 750,000 - 1,100,000; Full time

Job summary

Blykalla in Stockholm seeks a Senior Thermohydraulic Analyst to lead system-level analyses of the SEALER primary loop, supporting design-basis transients and safety demonstrations. You will perform CFD studies where needed, maintain TH models, and document assumptions.

You will collaborate with Nuclear and Safety, Test and Validation, and Materials teams, with strong emphasis on safety and accuracy. Fluent English is required; Swedish is a plus.

Qualifications

• Approximately 10+ years of thermohydraulic analysis experience in nuclear or related field.
• Degree in nuclear, mechanical, energy, chemical engineering, or related discipline.
• Hands-on experience with at least one nuclear system-level TH code (RELAP5/TRACE/CATHARE/APROS/MELCOR).
• Strong fundamentals in single-phase & two-phase TH, natural circulation, reactor safety analysis.
• Fluent scripting in Python or MATLAB for pre-/post-processing, studies, and uncertainty propagation.
• Ability to write rigorous technical reports that withstand independent review and regulatory scrutiny.
• Fluent in English; Swedish language is a plus.
• Experience with CFD tools (STAR-CCM+/ANSYS OpenFOAM) is highly valued.

Responsibilities

• Perform system-level thermohydraulic analyses of the SEALER primary loop under normal and design-basis transients.
• Perform CFD analyses on components/regions where system-level tools are insufficient.
• Support fluid system engineers with pressure drop budgets, transient response calculations, NPSH assessments, and related analyses.
• Set up and maintain plant TH models; document modelling assumptions, uncertainties, and limitations.
• Conduct sensitivity and uncertainty analyses to understand modelling impacts on design conclusions.
• Contribute TH input to safety analyses and interface with Nuclear and Safety team on accident analyses.
• Coach junior engineers on TH fundamentals, modelling practices, and code use.
• Support qualification, verification, and validation of in-house codes against benchmarks.

Skills

Thermohydraulic analysis

Nuclear industry experience

Python or MATLAB

CFD tools

Technical writing

English fluent

Swedish a plus

Lead-bismuth TH knowledge

Gen IV reactor familiarity

Code validation/compliance

Education

Engineering degree (Nuclear/Mechanical/Energy)

Tools

RELAP5

TRACE

CATHARE

MELCOR

STAR-CCM+

OpenFOAM

Job description

Blykalla in Stockholm seeks a Senior Thermohydraulic Analyst to lead system-level analyses of the SEALER primary loop, supporting design-basis transients and safety demonstrations. You will perform CFD studies where needed, maintain TH models, and document assumptions.

You will collaborate with Nuclear and Safety, Test and Validation, and Materials teams, with strong emphasis on safety and accuracy. Fluent English is required; Swedish is a plus.