The company

LeadCold Reactors (Blykalla Reaktorer) was founded in 2013 by J. Wallenius, P. Szakalos and J. Ejenstam as a joint stock company, with its basis in Stockholm. 


LeadCold is a spin-off from KTH Royal Institute of Technology in Stockholm, where J. Wallenius carried out research on design and safety analysis on lead-cooled reactor systems since 1996. The competences of the LeadCold team include fast reactor design, transient analysis, corrosion and materials science, nuclear fuel development, lead coolant chemistry, radiation damage, severe accident analysis, nuclear construction and operation of  nuclear power plants. 

Industrial partners

In 2021, LeadCold formed a joint venture with Uniper, the majority owner of the Oskarshamn nuclear power plant. The purpose of ”Swedish Modular Reactors AB” is to design and construct an electrically heated prototype of LeadCold’s SEALER reactor on the premises of OKG in Oskarshamn, Sweden.  Moreover, LeadCold is collaborating with TSP Engineering in Workington, UK on the design and manufacture of a compact steam generator for SEALER.

Scientific/Technical team

Janne Wallenius

Reactor physics

Peter Szakalos


Ignas Mickus

System Design

Staffan Qvist

Core design

Anders Blennermark

Configuration management

Karl-Axel Bartholf


Konny Njord


Lars Granström

Thermal hydraulics

Klara Insulander Björk


Jinzhen Leng

Control & safety

Management team

Olof Lindberg

CEO & Board Director

Janne Wallenius

CTO & Board Director

Peter Szakalos

CRO & Chair of board

Lars Franzén

Board Director

Anders Blennermark

Board Director


© LeadCold Reactors, 2022