Nuclear development in Brazil

BRAZIL IS VERY PROUD OF the good energy availability factor achieved by its two nuclear plants last year, when they ranked seventh in the world with a figure of 89.6%, Leonam Dos Santos Guimara~es, CEO of Eletronuclear told a webinar on Nuclear Power Developments in Brazil, organised by Nuclear Engineering International on 30 July. Eletronuclear is a subsidiary of state-controlled power utility Eletrobras, which accounts for 31% of installed capacity, 88% of which is hydropower. Nuclear power accounts for 3% of total energy production in Brazil, he said.

The first of Eletronuclear’s short-term goals is to reinforce safety culture, “because without a safety culture we can do nothing in nuclear”, he said. The second goal is continuous improvement in safety and performance of Angra 1 and 2. Completion of the used fuel dry storage facility is the third goal, as existing storage capacity will run out in June 2022 for Angra 1 and in August 2021 for Angra 2.

Leonam Dos Santos Guimara~es said life extension of Angra 1 to 2045 is the fourth goal and this should begin in 2024. A large amount of preparatory work is already completed. The work is being done in line with International Atomic Energy Agency (IAEA) standards and with US regulations, as Angra 1 is a Westinghouse reactor. Work has included two periodic safety reviews in 2004 and 2014 and an IAEA pre-Salto review mission in 2013.

The life extension process is expected to require investment of BRL1.2 billion ($230m). Angra 1 has already completed replacement of its steam generators in 2009, its reactor pressure vessel (RPV) closure head in 2013 and its main transformers in 2017. In 2019 it completed a mechanical stress improvement process on the pressure vessel nozzles.

The next goal is to resume construction of Angra 3, which was 67% complete when work stopped in 2015 due to the collapse of financial support. “We are making great efforts to restructure the financial support for the project and need BRL15 billion to finish the work,” he said. Civil structures have been built and the equipment supplied is being carefully maintained. Eletrobras has approved a Critical Path Acceleration Plan with the aim of completing the project by 2023, and says it has the financial resources for that. Commercial operation would start by the end of 2026.

Another important goal is to build new nuclear plants in Brazil, as the hydro potential is almost exhausted. The National Energy Plan to 2050 envisages additional nuclear capacity of 10GWe.

Eletronuclear has been working with EPE (Energy Research Company), COPPE-UFRJ (Federal University of Rio de Janeiro) and GARTA (Group for Analysis of Environmental Technologic Risk) on site selection and produced a ‘Brazilian Nuclear Atlas’ which shows all potential sites. “We started this work a long time ago but it was stopped. However, with the movement we have now through the National Energy Plan we will go ahead to select a site and technology for a new plant,” Dos Santos Guimara~es said.

He stressed the need to study the experience of other countries with respect to public attitudes, including government leadership, public opinion at the national and local level, the response to Fukushima, building public support and trust, understanding risk and risk governance and community benefit. In terms of the business model, it is necessary to consider the role of the market, ownership (state and private or national and foreign). Other key considerations are methods of financing and the supply chain and skills.

On the selection of PWR technology, he said it is necessary to consider plants already in operation, under construction or in the design stage as well as the selection of passive or active safety systems.

Angra 1 life extension

More details of the life extension programme were provided by Jose Augusto Ramos do Amaral, coordinator of Eletronuclear’s technical directorate and manager of the Angra 1 Long Term Operation (LTO) programme.

“We have been working for a long time with our nuclear regulator and environmental regulator and we are developing ageing studies for the systems, structures and components and of the plant, following the US Nuclear Regulatory Commission (NRC) approach for licence renewal with a hybrid approach using the IAEA PSR methodology,” he explained.

Angra nuclear power plant in Brazil

The aim is to extend the life of Angra 1 to 2045. The next periodic safety review will be in December 2023. A licence renewal application was submitted to the Brazilian regulator Comissa~o Nacional de Energia Nuclear (CNEN) in October 2019.

Augusto Ramos do Amaral said technical assessments within the LTO included:

• Integrated plant assessment (IPA)
• Time limited aging analysis (TLAA) review
• Obsolescence management
• Maintenance rules for active components

The IPA comprises ageing management review and ageing management programmes for passive long-lived systems and the evaluation and modification of plant programmes.

The ageing management programme is divided into four phases:

Phase 1 - a pilot programme applied to the residual heat removal system, elaboration of project procedures, and ALEX database development - was concluded in March 2010. Phase 2 - a time-limited aging analysis, which was reviewed by Westinghouse - was concluded September 2013.

Phase 3 – the IPA, to identify which structures and components are subjected to an ageing management review and to review plant procedures - started in 2015.

Phase 4 – improving the operation, maintenance and engineering programmes, and elaborate new programmes – has just been completed.

Eletronuclear is working closely with Westinghouse, which supplied the plant and is looking at the experience of more than 90 plants in the USA.

Actions already taken include:

• Replacing components to eliminate Cu-alloy in the secondary system with stainless steel tubes
• Implementing a fatigue monitoring programme
• Implementing a thermal stratification monitoring programme
• Ageing management assessments in the scope of the first PSR
• Implementing a flow accelerated corrosion programme
• Upgrading the obsolescence management programme
• Replacing the pressure vessel internals split pins
• Replacing steam generators
• Inspecting and repairing cabling inside the containment
• Weld overlay at the pressuriser surge line, spray line, safety valve lines, and relief valve line nozzles
• Replacing the pressure vessel closure head and control rod drive mechanisms (CRDMs)
• Time limited ageing analysis reviews, with external technical assistance from Westinghouse
• Hosting two IAEA Pre-SALTO missions at Angra 1, in November 2013 and May 2018
• Replacing the CRDM electric cables and connectors in the junction box area
• Reviewing the fire hazards analysis
• Developing inspections, condition evaluation, monitoring plan and maintenance plan for safety related civil structures (Concremat)

Eletronuclear has 70 other projects in development to assure the safety of the plant in the long term. These include: RPV baffle bolt inspection and repair, extension of the operating cycle from 12 to 18 months, digital I&C modernisation, replacement of electrical cables and penetrations, expansion of the used fuel dry storage facility and facility for low and medium level waste, modernisation of the radiation monitoring systems, a power uprate and fire detection system upgrade.

All this work is being done in co-operation with Westinghouse for the reactor, Siemens for the turbine and Holtec for the waste facilities. “All this is a big challenge”, Augusto Ramos do Amaral said. He noted that finance was being sought from US Eximbank along with support from the US and Brazilian governments. He stressed the importance of continued close co-operation with CNEN.

Building a dry storage facility at Angra

Lucio Dias B. Ferrari, design engineering superintendent at Eletronuclear, gave details of Brazil’s dry storage facility for spent fuel, which is to be built between Angra 2 and Angra 3. Currently fuel stays in the reactors for 3-4 years before being transferred to the used fuel storage pool, where it will remain for 10 years. However, the Angra 1 pool will reach full capacity in June 2022 and Angra 2 in August 2021. Eletronuclear decided to build a dry storage facility in 2015 and started an international bidding process in 2016. Holtec International won the bid and signed a contract in 2017. The contract is for services and supplies for the transfer of 510 used fuel assemblies and construction of an installation for 72 canisters containing about 2400 assemblies from Angra 1 and 2. This is a safe and proven technology based on a fully passive system which has been licensed by US NRC Currently there are more than 80 such installations in operation.

The facility will also be expected to house used fuel from Angra 3, which means that by 2090 the three units, operating for 60 years, will have produced 8300 fuel assemblies requiring 253 casks. First concrete for the first module of the storage pad was poured in June 2020 and construction of the warehouse and control cabin is underway. All the equipment will be delivered to Brazil by September, including Holtec’s Hi-Train-300 crane. Construction is expected to be completed by the end of this year with commissioning scheduled for the end of March 2021.

Eletronuclear faced a number of challenges in proceeding with this project. These included:

• Deciding on an appropriate technology for Brazil, at the right time, considering the short and long term.
• Evaluating, together with the nuclear and environmental authorities, the basis for licensing, and adopting international standards.
• Assuring public acceptance for the first installation of this type in Brazil.
• Preparing a good technical bidding specification for a turnkey contract, within a tight schedule and fixed completion time.
• Performing construction activities during the COVID-19 pandemic.
• Making the first ever transfer of used fuel assemblies in Brazil.

Ferrari said, “we are confident that in March next year we will complete pool to pad transfer from Angra 2 on time”.

Development of research reactors in Brazil

Jose Augusto Perrotta, technical coordinator of the Brazilian Multipurpose Research Reactor (RMB) Project at CNEN, described Brazil’s extensive experience in the development of research reactors and explained why a new one was needed.

Brazil has four research reactors. The 5MWt (originally 2MWt) IEA-RI open-pool type materials test reactor at the Nuclear and Energy Research Institute (IPEN) at Sa~o Paulo university, began operation in 1957 and is managed by CNEN. The 100kW IPN-RI Triga Mark 1 reactor started up in 1960, at the university of Belo Horizonte in the province of Minas Gerais. The 500kW Argonauta reactor, began operation at the University of Rio de Janeiro in 1965. These three research reactors laid the groundwork for the education of nuclear engineers and scientists in Brazil.

The fourth reactor was built in 1988 at IPEN. The MB-01 is a critical facility with a PWR core, designed and constructed in Brazil.

Perrotta explained that these three research reactors became the basis of large research institutes, but as they are all sited at university campuses within large cities, there is a limit to the possibilities for their expansion. So the new RMB, which will replace the IEA-RI, will be built at a new site outside the city limits of Sao Paolo. It will be a 30MW reactor, which can be used for radioisotope production for medical and industrial applications as well as for fuel and materials irradiation testing for nuclear plants, and for education and training. Brazil offers masters and doctorate degrees in the nuclear field and has 1000 students at its institutes. The RMB will have a neutron beam national laboratory and a NAA national laboratory.

RMB will play a key role in supplying radioisotopes for Brazil, which aims for national autonomy in producing radioisotopes for medicine, industry, agriculture and environmental applications. Currently Brazil carries out two million procedures every year using nuclear medicine. Perrota said it is currently difficult to import the radioisotopes needed for this because of restrictions on movement. The emphasis will be on Mo-99 production for Tc-99 provision for the nuclear medicine application.

This project comes under the Ministry of Science, Technology and Innovation and is the responsibility of CNEN’s Research and Development Directorate. Brazil’s five main research institutes are all involved in the project (IPEN, the Nuclear Technology Development Centre, the Institute of Nuclear Engineering, the Institute of Radiation Protection and Dosimetry and the Nuclear Sciences Regional Centre). There is also a partnership with naval company Amazo^nia Azul Tecnologias de Defesa and widespread support for the project from state and federal institutions and from the scientific community.

“It is a very important project for our country,” Perrotta noted.

The project is in mid development with site set-up, conceptual design, basic engineering design, fuel assembly design and fabrication, and environmental licensing complete. Nuclear licensing and the detailed engineering design is under way.

The main construction company is INVAP (Argentina), which joined with IPEN on the reactor design. Brazil has developed enrichment to 20% for the reactor fuel, at the Navy research centre in Sao Paolo. Fuel fabrication is at IPEN, which also supplies targets for isotope production.

The estimated cost of the RMB project is $500 million over a six-year period.

“Now we are just waiting for this budget to start the phase of construction and procurement,” Perrotta said.

He added that the new reactor with its supporting laboratories and facilities will eventually be the biggest and most important nuclear research centre in Brazil.

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Author information: Judith Perera, Contributing Editor, Nuclear Engineering International