ALKAZAR: FROM A LIMESTONE QUARRY THROUGH A SECRET THIRD REICH FACTORY TO A NUCLEAR WASTE REPOSITORY
History of the Hostim I Quarry
Before the now well-known name Alkazar became commonly used, the quarry carried its original operational name Hostim I. Among local people, the names V Kozle or Na Kozle were also used. The name Alkazar appeared only later and came from a romantic designation of the massive limestone cliffs, which reminded people of ancient fortresses known as alcázars.
The quarry is located in the Bohemian Karst near the village of Hostim close to Beroun. Its origin was connected with the extraction of high-quality limestone, which shaped the surrounding landscape for many decades. Quarrying gradually created extensive underground spaces and tunnels, which gained a completely new significance after mining activities ended.
It was precisely the combination of a stable rock massif, existing underground cavities, and a relatively hidden location that attracted projects which had nothing more to do with stone extraction.
A Secret Underground Factory of the Third Reich
Towards the end of the Second World War, German industry came under increasing pressure from Allied bombing raids. Strategically important factories on the surface became more and more vulnerable, which led the Third Reich to move parts of its production into underground facilities.
One of the selected locations was the Hostim I quarry. The original plan involved the construction of the secret underground factory Sigma III by the Škoda company. The adapted underground spaces were intended for the production of 75 mm tank guns for the German army.
However, the situation on the fronts changed rapidly – and so did the priorities of the German war industry. The Sigma III project was replaced by a new plan, and excavation of large underground production halls began under the code name Kainit.
These underground halls were intended to serve the Avia company for the production of aircraft engines. However, the work began only during the final phase of the war, and by May 1945 the entire project could no longer be completed. The planned factory hidden inside the rock therefore never entered production.
Forgotten Tunnels After the War
After liberation, the unfinished underground complex remained abandoned. The tunnels that were originally intended to protect German wartime production from air raids lost their purpose.
However, their location and characteristics meant that they were not forgotten forever. Only a few years later, they found an entirely different use – during the development of the Czechoslovak nuclear programme.
The First Czechoslovak Radioactive Waste Repository
During the 1950s, radioactive materials began to be increasingly used in Czechoslovakia in science, medicine, and industry. At the same time, the question arose of how to safely store waste created during work with radioisotopes.
The former tunnels of the Hostim I quarry were eventually chosen as a suitable location. Between 1959 and 1964, the Hostim radioactive waste repository operated here – one of the first facilities of its kind in Czechoslovakia.
Two main underground sections were used. Tunnel A was designated for waste from the Institute of Nuclear Physics in Řež. Tunnel B was used by the Prague Institute for Research, Production and Application of Radioisotopes, which later became connected with the system responsible for radioactive waste management.
No spent nuclear fuel from nuclear power plants was stored in Alkazar. The material consisted mainly of low- and intermediate-level radioactive waste originating from research facilities, medicine, and industrial applications of radioactive substances.
Closure and Securing of the Repository
Operation of the repository ended in 1964. Further storage of radioactive waste continued in newer and more suitable facilities.
Security measures continued in the following decades. In 1970, two shafts in the quarry area were filled with clay for safety reasons. This work was carried out by the Rudné doly Mořina mining company.
The final securing of the site took place in 1997. The repository was technically sealed again and concreted by the ARAO company in order to create a long-term barrier separating it from the surrounding environment and preventing unauthorized access.
Alkazar Today
Today, visitors know Alkazar mainly as a remarkable rock area in the Bohemian Karst. It is a popular place for hikers, climbers, and people travelling through the Berounka River valley.
Few of them realize, while looking at the quiet limestone cliffs, how many different stories this place hides. Within a single rock, stone quarrying, secret wartime projects, and the beginnings of the nuclear age all came together.
Alkazar is therefore not just a former quarry. It is a place where an extraordinary chronicle of the 20th century has been preserved beneath the surface of the landscape – from industrial development, through the darkest period of the war, to the era of nuclear technology.
