IAEA reviews long-term safety of Argentinean plant

The 11-member Pre-SALTO (Safety Aspects of Long Term Operation) mission team focused on aspects essential to the safe long-term operation of the 362 MWe (gross) pressurised heavy water reactor, which began commercial operation in 1974. Nucleoelectrica Argentina SA (NA-SA), operator of the plant, is preparing to extend its operating period until 2024. The review mission was requested by NA-SA.

The plant has made progress in ageing management and preparedness for long-term operation (LTO), the IAEA said. The team noted that the plant's LTO project already addresses several topics recommended by IAEA safety standards, with some activities partially implemented and many others already begun. The team - comprising nine experts from Belgium, Canada, Finland, Spain, Sweden, Switzerland and the UK, as well as two IAEA staff members - found plant personnel to be "professional, open and receptive to suggestions for improvement".

The team identified several good performances that will be shared with the nuclear industry globally. These included that the plant has implemented short-term trending of preventative maintenance activities, allowing for information to be validated and short-term abnormalities to be identified. Condition assessment reports in the mechanical area are well developed with regards to both traceability and completeness. In addition, the plant has also revalidated time limited ageing analysis (TLAA) to confirm effective management of cumulative fatigue in certain areas. TLAAs are plant calculations and analyses that consider the effects of ageing, involve time–limited assumptions defined by the current operating term and generate conclusions or provide the basis for conclusions related to the capability of a structure or component to perform its intended function.

The mission team provided several recommendations for further enhancing LTO safety at Atucha I, including that the plant should improve LTO organisational arrangements and processes to ensure timely implementation of all activities to demonstrate preparedness for safe LTO. The plant should also establish and consistently apply a clear and unambiguous scope setting methodology for LTO assessment. In addition, it should fully establish and implement a comprehensive equipment qualification programme.

The team provided a draft report to the plant management at the end of the mission. A final report will be submitted to the plant, the Argentinean regulatory authority and the government within three months.

The plant management said it was committed to implementing the recommendations and requested that the IAEA schedule a SALTO mission in November 2020.

A SALTO peer review is a comprehensive safety review addressing strategy and key elements for the safe long-term operation of nuclear power plants. SALTO missions complement IAEA Operational Safety Review Team (OSART) missions which are designed as a review of programmes and activities essential to operational safety. SALTO peer reviews can be carried out at any time during the lifetime of a nuclear power plant, although according to the IAEA the most suitable time lies within the last ten years of the plant's originally foreseen operating period. SALTO and OSART reviews are carried out at the request of the IAEA member country in which the review is to take place.

In April, Argentina's nuclear regulator issued an amendment to the operating licence of Atucha I, which authorises the start of Stage A of the plant's long-term operation. The Autoridad Regulatoria Nuclear said that during this phase progress will be made in the preparation of the plant's modernisation project, which would make its operation viable in the longer term, at Stage B. The new permit allows Atucha 1 to operate for five years of full power generation, or until 29 September 2024, the end date of the current periodic safety review, whichever occurs first.

Atucha is home to two of Argentina's three operating nuclear power plants, all pressurised heavy water reactors. With total generating capacity of 1627 MWe, the three units - Atucha I and II plus Embalse - provide about 10% of the country's electricity. A prototype domestically designed and developed 25 MWe small pressurised water reactor - CAREM - is under construction at a site adjacent to the Atucha plant.