The nuclear power plant A1 was designed as an experiment with possibility of energy production. It was constructed between 1958 and 1972. Natural (unenriched) metallic uranium was used as fuel. The main characteristic of this power plant was a two-circuit construction of the reactor. It had a separate circuit of coolant used for cooling the fuel assemblies and the moderator, which reduced the energy of neutrons in the reactor and thus affected fission as well as other reactions. Carbon dioxide was used to cool the active zone. Heavy water was used as a moderator. The power plant operated at different output levels from 1972 to 1977.

Two incidents occurred during its operation. During the first incident in 1976, a fresh fuel assembly was ejected into the reactor hall after its loading in the cooling channel of the active zone (fuel replacement in this reactor was executed continually without pausing the operation of the reactor), which resulted in subsequent loss of tightness of the reactor and leakage of cooling carbon dioxide. Overheating of the fuel assembly resulting from the incomplete removal of absorbing material, which was inserted into the fuel assemblies in order to absorb moisture during the storage, caused the second incident in 1977. Consequently, moderator penetrated the cooling circuit of carbon dioxide, which damaged the fuel cladding. The power plant was permanently shut down after the second incident.

The process of decommissioning, also due to the above-mentioned reasons, was preceded by a long preparatory stage. The whole process was divided into 5 subsequent stages scheduled from 1999 to 2033. Specific feature of decommissioning of this particular power plant is the fact that some facilities will be re-classified under nuclear installations of Technologies for treatment and conditioning of radioactive waste (TTC RAW), with which this power plant is spatially and technologically interconnected. Therefore, the demolition costs of these installations are included in the costs of decommissioning of non-reactor nuclear facilities TTC RAW. Another specific feature is the presence of contaminated soils and concrete at the plant site.

The third and the fourth stage of decommissioning of this nuclear power plant is currently in progress.

The time line and overview of crucial activities implemented before decommissioning as well as during its all stages are depicted in following charts.

Costs for decommissioning of this nuclear power plant are covered from the levy collected by the operators of transmission and distribution systems. The levy serves to repay the so-called historical debt arisen in respect of the formation of resources for the coverage of the costs connected with the back-end of nuclear power engineering. This levy is collected from end-users of electricity, forms part of price for delivered electricity and serves not only to cover the costs connected with the back-end of the nuclear power plant A1, but also the costs for activities related to the back-end of the nuclear power plant V1.

The NJF creates dedicated sub-accounts and analytical accounts from its resources, while the financial resources intended for the decommissioning of the nuclear power plant A1 and for the management of radioactive waste from this decommissioning (with the exception of radioactive waste disposal) are accumulated in the analytical account of the nuclear power plant A1. Resources for decommissioning of the nuclear power plant A1 are provided from this analytical account to the applicants, who fulfill all the conditions pursuant to Act No. 308/2018 Coll. on the National Nuclear Fund. Financial resources for the decommissioning of the nuclear power plant A1 and for the management of radioactive waste from this decommissioning are currently provided to the company JAVYS, a. s., which annually submits the applications for provision of financial resources from the NJF and the licence holder for decommissioning of this power plant. The total amount of financial resources spent for the coverage of costs in the analytical account of the nuclear power plant A1 from 1995 to 2018 is € 682.7 million. This sum includes financial resources spent for decommissioning itself, management, repairs and maintenance of facilities of the nuclear power plant A1, innovation, enlargement and refurbishment of facilities, as well as management of radioactive waste from decommissioning (with the exception of radioactive waste disposal). Financial resources for the disposal of low-activity and very low-level waste from decommissioning of the nuclear power plant A1 are provided from the analytical account e) „The National Radioactive Waste Repository in the locality of Mochovce“.

Eligible costs connected with the implementation and ensuring of decommissioning activities of the nuclear power plant A1 from 2015 to 2033 with regard to the current National Programme for the Management of Radioactive Waste and Spent Nuclear Fuel were estimated at € 578.4 million (at the price level of 2014, with the exception of radioactive waste disposal).