EPR (nuclear reactor)
The EPR is a Generation III+ pressurised water reactor design. It has been designed and developed mainly by Framatome and Électricité de France in France, and by Siemens in Germany. In Europe, this reactor design was called European Pressurised Reactor, and the internationalised name was Evolutionary Power Reactor, but it has been simplified to EPR.
The first operational EPR unit was China's Taishan1, which started commercial operation in December 2018. Taishan2 started commercial operation in September 2019. European units have been so far plagued with prolonged construction delays and substantial cost overruns. The first EPR unit to start construction, at Olkiluoto in Finland, originally intended to be commissioned in 2009, started commercial operation in 2023, a delay of fourteen years. The second EPR unit to start construction, at Flamanville in France, also suffered a more than decade-long delay in its commissioning. Two units at Hinkley Point in the United Kingdom received final approval in September 2016; the first unit was expected to begin operating in 2027, but was subsequently delayed to around 2030.
EDF has acknowledged severe difficulties in building the EPR design. In September 2015, EDF stated that the design of a "New Model" EPR was being worked on and that it would be easier and cheaper to build.
EPR type reactor has a design service lifetime of 60 years.
Design
First EPR design
The main objectives of the third generation EPR design are increased safety while providing enhanced economic competitiveness through improvements to previous pressurised water reactor designs scaled up to an electrical power output of around 1650MWe with thermal power of 4500MW. The reactor can use 5% enriched uranium oxide fuel, reprocessed uranium fuel or 100%mixed uranium plutonium oxide fuel, clad in Areva's M5 variant of zirconium alloy. The EPR is the evolutionary descendant of the Framatome N4 and Siemens Power Generation Division "" reactors. Siemens ceased its nuclear activities in 2011.The EPR was designed to use uranium more efficiently than older Generation II reactors, using approximately 17% less uranium per kilowatt-hour of electricity generated than these older reactor technologies.
The design has gone through a number of iterations. The 1994 conceptual design had an electrical power output of 1450MW, the same as the Framatome N4, but using Siemens Konvoi derived instrumentation and also including a new core catcher safety system. By 1995, there was concern over excessive cost per MW, and output was raised to 1800MW in the 1997 design, though this was subsequently reduced to 1650MW in the final certified design. It has 4 coolant loops with 1 steam generator per loop. There are concrete walls between loops and the hot and cold parts of each loop to protect against failures. Besides the double layer containment there is a concrete wall surrounding the primary system components inside the containment.
The EPR design has several active and passive protection measures against accidents:
- Four independent emergency cooling systems, each providing the required cooling of the decay heat
- Leak-tight containment around the reactor
- An extra container and cooling area if a molten core manages to escape the reactor
- Two-layer concrete wall with a total thickness of, designed to withstand impact by aeroplanes and internal overpressure, and a low vacuum in the annulus space between the two layers
Technical specifications
EPR2 design
, EDF acknowledged the difficulties it was having building the EPR design, with its head of production and engineering, Hervé Machenaud, saying EDF had lost its dominant international position in design and construction of nuclear power stations. Machenaud indicated EDF was considering designing two new lower powered reactors, one with output of 1500MW and the other 1000MW. Machenaud stated there would be a period of reflection on the best way to improve the EPR design to lower its price and incorporate post-Fukushima safety improvements.In September 2015, EDF's chief executive Jean-Bernard Lévy stated that the design of a "New Model" EPR, or "EPR2", was being worked on, which would be easier to build, and be ready for orders from about 2020, describing it in 2016 as "a reactor offering the same characteristics as today's EPR but it will be cheaper to build with optimised construction times and costs".
In 2016, EDF planned to build two new model EPR reactors in France by 2030 to prepare for renewing its fleet of older reactors. However, following financial difficulties at Areva and its merger with EDF, French Ecology Minister Nicolas Hulot said in January 2018, "for now is neither a priority or a plan. Right now the priority is to develop renewable energy and to reduce the share of nuclear." The industry-government plan for 2019–2022 included work on "a new version of the EPR".
In July 2019, the French nuclear safety authority ASN issued an opinion on the safety of an outlined new EPR model design. It found that general safety was on the whole satisfactory, though identifying areas for further examination. The most notable simplification is a single layer containment building with a liner as opposed to the EPR's double layer with a liner. ASN highlighted that the EPR design basis assumption that primary and secondary cooling circuit piping would not fail may no longer be appropriate for the simplified EPR2, and requires additional safety demonstrations. Another simplification is that, unlike the first EPR design, the EPR2 design does not allow access to the reactor building for maintenance during reactor operation, which simplifies the design of the reactor building.
In 2020, French Energy Minister Élisabeth Borne announced the French government would not decide on the construction of any new reactors until the much delayed Flamanville 3 started operation after 2022. EDF had estimated that building six EPR2 nuclear reactors would cost at least €46billion. A Court of Audit report concluded that EDF is no longer able to finance EPR2 construction on its own, so financing and profitability issues need to be resolved.
The audit office requires that EDF ensure the financing and profitability of EPR2 before constructing any in France.
In January 2022, junior environment minister Bérangère Abba said that plans for new EPR2 reactors, to be operational between 2035 and 2037, should be submitted around 2023. The decision was accelerated by the impact of the 2021 global energy crisis. In June 2023, EDF announced it was starting the authorisation process to build two EPR2 reactors at Penly Nuclear Power Plant.
The EPR2 requires 250 types of pipes instead of 400 for the EPR, 571 valves instead of 13,300 valves for the EPR, and 100 types of doors instead of 300 in the EPR. The EPR2 also uses more prefabricated components, and the electrical buildings can be completely prefabricated. The fourth emergency/safety cooling system/train of the reactor is removed which means maintenance can only be performed when the plant is shut down. This train was added at the request of German electricians in the original EPR design to allow for on-power maintenance. The core catcher has been modified. It has a net power output of 1670MWe.
EPR1200 design
A smaller variant of the EPR2 is being developed using three instead of four coolant loops generating 1200MW net of electrical power, the EPR1200, intended for export. In February 2023, regulator ASN issued a positive opinion on the safety features of the EPR1200.Operational plants
Olkiluoto 3 (Finland)
Construction of the Olkiluoto 3 power station in Finland began in August 2005. The station has an electrical power output of 1600MWe. The construction was a joint effort of French Areva and German Siemens AG through their common subsidiary Areva NP, for Finnish operator TVO. Siemens ceased nuclear activities in 2011. Initial cost estimates were about €3.7billion, but the project has since seen several severe cost increases and delays, with latest published cost estimates of more than €8billion. The station was initially scheduled to go online in 2009.In May 2006, construction delays of about one year were announced, following quality control problems across the construction. In part, the delays were due to the lack of oversight of subcontractors inexperienced in nuclear construction. The delays led to disappointing financial results for Areva. It blamed delays on the Finnish approach to approving technical documentation and designs.
In December 2006, TVO announced construction was about 18 months behind schedule so completion was now expected 2010–11, and there were reports that Areva was preparing to take a €500million charge on its accounts for the delay.
At the end of June 2007, it was reported that Säteilyturvakeskus, the Finnish Radiation and Nuclear Safety Authority, had found a number of safety-related design and manufacturing 'deficiencies'. In August 2007, a further construction delay of up to a year was reported associated with construction problems in reinforcing the reactor building to withstand an aeroplane crash, and the timely supply of adequate documentation to the Finnish authorities.
In September 2007, TVO reported the construction delay as "at least two years" and costs more than 25% over budget. Cost estimates by analysts for the overrun range up to €1.5billion.
A further delay was announced in October 2008, making the total delay three years, giving an expected online date of 2012. The parties entered into arbitration to resolve a dispute over responsibility for the delays and final cost overruns. Areva settled the long-running dispute in 2018 by agreeing to pay €450million for cost overruns and delays.
As of May 2009, the station was at least three and a half years behind schedule and more than 50 percent over-budget. Areva and the utility involved "are in bitter dispute over who will bear the cost overruns and there is a real risk now that the utility will default". In August 2009, Areva announced €550million additional provisions for the build, taking station costs to €5.3billion, and wiped out interim operating profits for the first half-year of 2009.
The dome of the containment structure was topped out in September 2009. 90% of procurement, 80% of engineering works and 73% of civil works were completed.
In June 2010, Areva announced €400million of further provisions, taking the cost overrun to €2.7billion. The timescale slipped from June 2012 to the end of 2012. In December 2011, TVO announced a further delay to August 2014. As of July 2012, the station was scheduled to start electricity production no earlier than 2015, a schedule slippage of at least six years. In December 2012 Areva's Chief Executive estimated costs to €8billion.
In September 2014, Areva announced that operations would start in 2018. In October 2017, the date was pushed back to the spring of 2019. During testing between 2018 and 2021, multiple further delays were announced, of around three years in total.
Olkiluoto 3 achieved first criticality in December 2021. Grid connection took place in March 2022. In May 2022, foreign material was found in the turbine steam reheater, and the plant was shut down for about three months of repair work. Regular production had been expected to begin in December 2022, after a test production phase. On 28 October 2022, it was announced cracks of a few centimetres had been found in all four of the feedwater pump impellers. The cause of the cracks was yet to be determined, and it was unclear how the commissioning schedule would be affected. The feedwater pumps are larger than in other nuclear reactors.
Olkiluoto 3 started regular electricity production in April 2023.