Argentina’s Nuclear Regulatory Authority (ARN – La Autoridad Regulatoria Nuclear) has provided an update on plans for the Long-Term Operation (LTO) of unit 1 at the Atucha NPP. The LTO project comprises two stages: A and B, and the execution of a Prolonged Period of Reconditioning (PPR), which will begin this year.

When nuclear utility Nucleoeléctrica Argentina SA (NA-SA) notified ARN oof its intention to extend the life of the Atucha 1 beyond its original design life, in line regulatory requirements, NA-SA carried out exhaustive evaluations on different aspects of the nuclear power plant and its past operation. These were independently reviewed by ARN, which concluded that the safe operation of Atucha I beyond its original design life was possible. ARN determined the need for the execution of various activities and the LTO project was divided into two stages: A and B.

Stage A was authorised by ARN through an amendment to Atucha 1’s operating licence in April 2018. This allowed NA-SA to continue operation of the unit during this stage while it undertook studies and establish programmes that would ensure that the design bases of the installation were maintained. Studies and maintenance tasks necessary to meet this requirement had to obtain ARN approval.

Currently, Atucha 1 is nearing the end of stage A. In 2024 the PPR will begin, which has a minimum expected duration of two and a half years. During this time, RNA will verify in detail the implementation of the updates and improvements required from NA-SA to raise the design bases of the facility to a higher level of security than the one with which it was originally licensed.

During the PPR outage Atucha I will carry out a series of relevant updates and improvements to elevate the facility’s design bases to a higher level of security. This will result in a plant with safety characteristics superior to the original design. The selection of these improvements was defined following extensive evaluations required and reviewed by ARN, taking into account the security impact, its applicability and its justification in relation to the design of the plant.

The original design life Atucha 1 was 32 equivalent years of full power, established in its initial operating licence and incorporated in the renewed licence issued by ARN in 2014. In order to grant this renewal ARN required NA-SA to execute a Periodic Security Review.

When it comes to licensing, the current 2018 operating licence has an established validity of five years of operation at full power or 10 calendar years from the previous renewal (2014), whichever comes first. Since the mentioned milestones would be reached, in practical terms, with a difference of a few months, NA-SA asked ARN to operate the plant until the maximum date provided for in the conditions, that is, for the 10 calendar years that would end on 29 September 2024. For the purposes of determining the acceptability of this request, ARN says it is evaluating compliance with the regulatory requirements established for stage A of the LTO, as well as the operational performance of the installation so far.

Stage B includes LTO after the implementation of relevant updates and improvements. Most of these will be done during the PPR outage.