Author: Nikola Slívová Affiliation: Criminalistics and Forensic Studies, University of Finance and Administration, Prague Keywords: nuclear accident, CBRNE, radiological contamination, INES, emergency preparedness
Introduction
Jaslovské Bohunice, located in western Slovakia (then Czechoslovakia), is the site of one of the most significant nuclear accidents in Central European history. The A-1 Nuclear Power Plant, housing the experimental KS 150 heavy-water-moderated, carbon-dioxide-cooled reactor (HWGCR), experienced two major accidents during refuelling operations in 1976 and 1977, providing a compelling case study for CBRNE analysis. This article synthesizes publicly available technical and institutional sources to examine the CBRNE-relevant causes, consequences, and lessons of the Bohunice A-1 accidents through a rapid literature screening of peer-reviewed papers, official decommissioning reports, and IAEA-referenced databases.
Results
The KS 150 reactor was a first-generation channel-type reactor with an electrical output of 143 MWe, using natural metallic uranium as fuel, heavy water as a moderator, and carbon dioxide as coolant. Its design allowed on-power refuelling, which created repeated human-machine interfaces susceptible to procedural failure. Due to its experimental nature, the plant suffered over 30 unplanned shutdowns throughout its operational life.
On 5 January 1976, a mechanical failure during fuel loading caused a fresh fuel assembly to be ejected from the reactor into the reactor hall. The escaping carbon dioxide — a gas heavier than air — flooded the lower spaces of the reactor building, asphyxiating two workers: Libor Benda (57) and Izidor Ferech (52). Although no significant release of fission products occurred, the incident demonstrated that non-radiological chemical hazards (i.e., the "C" in CBRNE) can be lethal in nuclear environments.
The more severe accident occurred on 22 February 1977 during routine refuelling. Personnel failed to remove silica gel packets, used as moisture absorbents during fuel storage, from a fresh fuel assembly before loading it into the reactor. The residual silica gel restricted coolant gas flow, causing local overheating, which melted fuel rods and burned through the moderator vessel tube. This allowed heavy water to enter the primary gas circuit, rapidly increasing humidity and causing extensive corrosion damage to fuel cladding throughout the reactor. Both the primary and secondary circuits became heavily contaminated with fission products. The accident was rated INES Level 4 — an "Accident with Local Consequences" — placing it one level below Three Mile Island (INES 5) and three levels below Chernobyl (INES 7). On 17 May 1979, the Czechoslovak government ordered the permanent shutdown and decommissioning of the plant.
Subsequent environmental monitoring revealed contamination of soils in the A-1 area, as well as of the Manivier Canal and Dudvah River due to flooding events during decommissioning. The decommissioning process, managed by JAVYS, was initiated in 1999 and is divided into five stages with completion projected for 2033.
Discussion
From a CBRNE preparedness perspective, the Jaslovské Bohunice case offers several transferable lessons. First, the 1976 event illustrates the importance of integrating chemical-hazard protocols (asphyxiant gas management) into nuclear facility emergency planning. Second, the 1977 accident is a textbook example of how human error in routine procedural tasks — failure to verify removal of silica gel — can trigger a cascading radiological contamination event, underscoring the need for robust checklists, independent verification, and safety culture. Third, the long-term environmental monitoring and decommissioning challenges reinforce the principle that CBRNE response extends far beyond the acute phase into decades of remediation and waste management.
References
- Kuruc, J., Mátel, Ľ. (2007). Thirtieth Anniversary of Reactor Accident in A-1 Nuclear Power Plant Jaslovske Bohunice. Folia Veterinaria / Conference Proceedings, Comenius University. https://www.osti.gov/etdeweb/biblio/20895814
- Wikipedia contributors (2025). KS 150. Wikipedia, The Free Encyclopedia. https://en.wikipedia.org/wiki/KS_150
- JAVYS, a.s. (n.d.). Technology — A1 Nuclear Power Plant. https://www.javys.sk/en/nuclear-facilities/a1-nuclear-power-plant/technology
- JAVYS, a.s. (n.d.). History — Nuclear Facilities. https://www.javys.sk/en/nuclear-facilities
- Frost, N. (2025). Jaslovské Bohunice, Slovakia (then Czechoslovakia) — Fuel Damaged. Reveal.World. https://reveal.world/en/story/jaslovske-bohunice-slovakia-then-czechoslovakia-fuel-damaged
- IAEA/OECD-NEA (n.d.). International Nuclear and Radiological Event Scale (INES). https://www.hko.gov.hk/en/radiation/monitoring/ines.html
- Kuruc, J., Mátel, Ľ. (2006). 30th and 29th Anniversary of Reactor Accidents in A-1 Nuclear Power Plant Jaslovske Bohunice — Radioecological and Radiobiological Consequences. http://www.omegainfo.sk/Kuruc_28DRO_2006.pdf
- JAVYS, a.s. (2016). Decommissioning of Nuclear Facilities — Jaslovské Bohunice Site A1. https://www.javys.sk/data/web/dokumenty/Publikacie/brozura-2016/vyradovanie-je-a1-eng.pdf
VIMY Knowledge: let's think about it. Scientific Posts/Series are part of a prospective research program. Authors declare no conflict of interests. © (MD) 2026 Operation Compagnons D'Armes.