‘We have always focused on safety,' says Areva India chief

| | Updated on: May 02, 2011
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In the backdrop of the nuclear incident in Japan, the nuclear industry worldwide has been forced to do a reality check on future plans. French reactor manufacturer Areva, which is set to commence work on its EPR reactor-based project at Jaitapur in Maharashtra, is confident about the safety systems built into its third generation pressurised water reactors. In an interview with the Business Line , Areva India chief, Mr Arthur De Montalembert, shares his views. Excerpts:

There is a general feeling that the nuclear industry globally has not always been transparent about risks and people have been repeatedly told that distrusting new technology is unwarranted. Do you think the disaster in Japan could possibly force a rethinking among both reactor manufacturers and operators to allay public concerns adequately before going ahead with new projects?

In France, as in most countries having nuclear reactors, the law institutes an independent nuclear watchdog, the Authority on Nuclear Safety (ASN), whose mandate is to regulate nuclear safety and radioprotection for all nuclear facilities, including new constructions. The law also institutes an independent High Committee for Transparency and Information on Nuclear Safety (HCTISN) whose mandate is to promote information, consultation and debate on the potential risks and impact from nuclear activities on health and environment. Thanks to such instances, France has always had a healthy debate about nuclear, and all queries and changes requested for by regulators have been complied with.

As for Areva, we have had a history of being transparent with all processes and systems. We have always focused on safety, which is the starting point of any project we plan. Safety does of course come at a higher capital cost, which we overcome with enhanced capacity, efficiency and plant life that help power utilities produce affordable power for the consumer.

As you may be aware, France has one of the worlds' lowest costs of per MW power, which is comparable even to power costs being paid by consumers in India.

Inherently, are pressurised water reactors (PWRs) safer than boiling water reactors (BWRs), specifically, in terms of being easier to breach the primary circuit on a BWRs than on PWRs?

The two technologies are different and both can be operated safely. Areva has used the PWR technology as the standard for the majority of reactors it supplied so far, as well as for the state-of-the-art ‘Gen-3+' EPR and Atmea-1 reactors. Areva also supplied BWR reactors, mainly to Germany where their safety and performance have been outstanding, and we are currently developing a ‘Gen-3+' BWR reactor called Kerena.

Areva has claimed that its third-generation EPRs are among the safest in the world. Are these features adequate in the light of the accident in Japan?

As an evolutionary design, the EPR reactor combines proven safety systems inherited from its highly efficient “parent” reactors, the French N4 and the German Konvoi, which total more than a hundred years of safe and effective operation and have generated over 1,160 TWh of electricity so far, and, innovative features that integrate the return on experience from past industry events. The EPR reactor therefore meets the highest safety requirements of the world's leading regulatory authorities and offers in-depth protection against both external and internal accidents.

If an event should occur that upsets the regular functioning of the EPR, control rods that stop the nuclear reaction would fall automatically into the core, shutting down the reactor while the cooling system would remove the residual heat. The main feed water system is the normal operational method of cooling the EPR reactor. It provides water to the secondary circuit (the steam circuit used to drive the electrical turbine) to remove heat from the reactor cooling circuit (the primary circuit). In case of loss of power from the grid, back-up cooling would be provided by four redundant safety systems located in four separated buildings, each of them being able to cool the reactor by itself.

Each cooling system is composed by an optimised combination of active and passive features: A safety injection system that uses pumps and valves (active), as well as four large pressurised accumulator water tanks that empty automatically as the system pressure is reduced (passive). Power supply to each system is secured by four dedicated emergency diesel generators (EDG) housed in two separate buildings which are designed to be anti-seismic and specifically laid out to provide protection against floods and tsunamis (adaptations being made according to site-specific requirements). Moreover, each of the separate buildings is located on either side of the plant, making it very unlikely for both of them to be damaged by external impact hazards.

If all four emergency diesel generators should fail to start, two additional station blackout diesel generators are available to provide power to essential equipment and remove core heat until power is restored. Moreover, in case of loss of the main cooling source, in addition to each of the 50 cubic metres tanks of borated water present in the accumulator (pressurised tanks) of each safeguard division, the EPR contains an emergency feedwater tank of 1,600 cubic metres which would provide time to put a more sustainable solution in place. Finally, another cooling source available in the EPR is the IRWST (In-Reactor building Water Storage Tank) with an additional 1800 cubic metres. This water can be used for safety injection to cool the core. The steam produced in the process condensates back to the IRWST to be further re-circulated.

In the extremely unlikely event of a core meltdown situation, the EPR reactor has been designed to prevent any exposure of the corium to external air. A passive safety system, requiring no human intervention, would ensure that the corium automatically falls in a core-catcher where it would be automatically flooded, thanks to gravity, by the water storage tank housed in the reactor building (the IRWST). In addition, the core catcher is designed in such a way that the corium will cause no damage to the basement of the building. In the same time, spray nozzles will spray water from the ceiling to control residual heat and pressure in the entire reactor building.

To avoid hydrogen-based explosions inside the reactor building, 48 passive autocatalytic recombiners would combine hydrogen releases with oxygen to make water. This process is chemically activated and thus does not require any electrical power. But even in the case of hydrogen combustion inside the containment building, its steel-lined structure made from pre-stressed concrete has been designed to withstand the deflagration without losing integrity.

The double concrete shell of the reactor is designed to avoid critical damage to the building structure, both from external and internal sources. The outer shell can absorb the impact of a large commercial aircraft whereas the inner shell can endure high pressure. As a last resort, this double shell would be capable of preventing any radioactive leakage.

Finally, the EPR reactor does not house the fuel pool in the reactor building, but in a separate and dedicated fuel building which is also protected by a double concrete shell. This, again, protects the pool from external hazards and prevents any external release.

The residual heat of the used fuel stored in the pool is removed by two physically separated and independent cooling water systems and a third back-up cooling system is available in case of common failure of the latter, to ensure that the temperature of the pool remains under control. Under electrical power default situation, the emergency diesel generators (EDG) supported by the two station blackout diesel generators would take over to keep the fuel pool cooling systems operating.

In addition, the pools are designed in such way that there is about 10 meters of water above the used fuel assemblies, stored primarily for radiological protection purposes, which will give operators valuable additional time (days, even weeks depending on the conditions) to find alternative solutions in the very unlikely case of failure of all the above safety systems.

As described above, the EPR design relies on optimised safety system architecture to achieve the level of safety that is required. It integrates the best technologies to maximise the overall safety of the plant.

Are there any specific additional safety features that you think might be necessitated in the third generation EPR design in the wake of the Fukushima incident?

As you are aware, there is a global safety check going on under the responsibility of nuclear safety regulators in each and every country having nuclear power plants in operation or in construction. There may be lessons to learn from the Fukushima accident in three areas: Design robustness, operations and crisis management. As far as design is concerned, there is no major change expected for the EPR because of its already very high safety level, as described above. Nevertheless, we are ready to address any query from nuclear safety regulators.

A group of 15 nuclear experts has written to the IAEA Director General on the need to beef-up safety, after Fukushima, in the interest of the future of the nuclear industry. One of the suggestions is that ‘NPP (nuclear power project) vendor countries should establish centres to train specialists for nuclear technology in recipient countries'. Will the French Government and Areva consider this as an option for Jaitapur?

While we are not in a position to comment on the outcome of the discussions you have referred to, we at Areva have already offered information sharing and training systems to India and to NPCIL in particular, in order to ensure safe and reliable operation of the reactors.

We remain open to new ideas in that direction. As a matter of reference, Areva has already undertaken technical information sharing with Indian partners, such as L&T, to manufacture components for our global customers. Areva is more than willing to support India's already highly robust nuclear power programme and help put it on the world stage.

Published on March 12, 2018

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