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Nuclear News - Nuclear Monitor #818 - 11 Feb 2016

Nuclear Monitor Issue: 

French government report questions passive safety systems

The French Institut de Radioprotection et de Sûreté Nucléaire (IRSN) has released a report questioning claims made about so-called passive nuclear reactor safety systems. The report outlines the main characteristics of passive safety systems and the main difficulties associated with assessing their performance and reliability, as well as priority research areas to be developed in order to overcome these difficulties.

Passive safety systems aim to bring the reactor to a safe shutdown state and maintain this state for a long period of time without need for human intervention and with limited reliance on support functions. They are mainly characterized by reduced reliance on active components for proper actuation; reliance on natural phenomena (gravity, differential pressure, etc.) for proper operation; not requiring support functions for proper operation; and not requiring human intervention for actuation and operation.

IRSN identifies a number of intrinsic difficulties, particularly concerning the following:

1. Performance assessment: assessing the performance of passive safety systems requires a very good understanding of the physical phenomena underlying their operation, as well as the necessary simulation capabilities for such phenomena;

2. Reliability assessment: specific development approaches appear to be necessary in order to properly evaluate the reliability of passive safety systems, with particular emphasis on assessing the failure probabilities of thermal-hydraulic mechanisms used by these systems.

The report notes that the demonstration of passive safety systems in reduced-scale tests raises the issue of their representativity and transposition to full-scale operating reactors.

The effective operation of passive safety systems may depend on ambient conditions (e.g. containment temperature increase caused by initiating event) or external hazards (climatic, seismic, etc.).

The report questions the passivity of some 'passive' safety systems:

"However, caution should be exercised as to the truly passive nature of safety systems which, according to their designers, rely solely on natural phenomena. Indeed, most of these systems rely on changes in mechanical equipment status (e.g. valve open), actuation signals and battery power.

"Furthermore, a passive safety system may not be capable of performing its assigned function, even
in the absence of mechanical or electrical failure. Indeed ... a passive safety system may rely on low-intensity phenomena (e.g. natural convection) which, under certain conditions, may be insufficient to perform its function. Such failure may occur when the phenomena at play are sensitive to system geometry (e.g. head loss sensitivity), ambient parameters and mismatches between design expectations and actual conditions.

"This type of failure, referred to as a functional failure, may lead to non-actuation or shutdown of a passive safety system, or unexpected operating conditions. If the same phenomenon is used to ensure proper operation of various passive safety system components, a functional failure could affect all components. This is referred to as a common mode failure."

The report states that further research is required in order to properly assess the performance and reliability of passive safety systems to be implemented in new reactor designs.

IRSN, January 2016, 'Considerations on the performance and reliability of passive safety systems for nuclear reactors',

PGE EJ1 cancels plans to build a nuclear power plant in the Lubiatowo Dunes

According to information received by Greenpeace, the Polish utility PGE EJ1 has removed the location 'Choczewo' from the list of potential sites for the construction of the first Polish nuclear power plant and has no plans to conduct further preparatory work on the site. According to Greenpeace, this is a good step toward ditching the costly and inefficient nuclear program.

The Lubiatowo Dunes, where PGE EJ1 planned the construction of a nuclear power plant, is one of the most beautiful dune areas in the country, and falls under protection of the European Habitat and Bird directives.

One of the sites still under consideration for a nuclear plant is just 4 kms to the west, and also threatens dunes and a vital corridor for animals and birds. Another site being considered is the site of the old and never finished Zarnowiec nuclear power plant – with too little cooling water available and currently hosting a breeding colony of different coastal and sea birds.

Jan Haverkamp, Greenpeace Central and Eastern Europe expert in the field of nuclear energy and energy policy, said: "The decision to abandon the idea for a nuclear power plant in the Lubiatowo Dunes was taken shortly before the fifth anniversary of the Fukushima disaster, and is an important step towards the withdrawal of PGE EJ1 from its costly nuclear fantasies. Nuclear power is not necessary for the phase-out of Poland's unhealthy addiction to coal. It is a risky technology and too costly for the Polish consumer. A realistic scenario for Poland is to increase energy efficiency and develop the production of affordable energy from wind, solar and sustainable biomass."

The results of expert analysis clearly indicate that nuclear power is the most expensive and inefficient way of producing energy for Poland. Iwo Los, Greenpeace expert on energy security in Poland, said the entire nuclear program, already delayed for several years, could cost up to €160 billion. Poland has no power reactors but six are planned.

More information:

Europe's challenging nuclear future

In a leaked draft document obtained by Energy Post, the European Commission (EC) outlines the bleak future facing the nuclear power industry in EU.1

The "Communication for a Nuclear Illustrative Programme" or PINC is a report produced periodically by the Commission. The draft report states that 27% of electricity in the EU is currently produced from nuclear energy and 27% from renewables. It estimates that nuclear electricity generation capacity will decline by 20% by 2025; and that nuclear capacity in 2050 will be 95–105 GWe, well short of the current figure of 121 GWe. Nuclear's share of electricity generation is expected to fall from 27% now to 17– 21% in 2050. (A 2013 EC report estimates that nuclear capacity in 2050 would be considerably higher, 122 GWe.2 French legislation to reduce nuclear's share from 75% to 50% of electricity generation is the main reason for the lower expectations in the latest EC report.)

The EC report notes that there is a "historical trend of cost escalation" for nuclear power. Even in France, construction costs per MWe in 1974 were three times lower than those of units connected to the grid after 1990. Building ever-bigger reactors means longer construction times with major impacts on cost. Moreover the EC believes that the investment cost (per KW) of small modular reactors is likely to be higher than for large plants.

The average age of the nuclear fleet in Europe is 29 years, and by 2030 most of the fleet will be operating beyond its original design life. More than 50 of the EU's 131 reactors are likely to be shut down by 2025, the EC report says.

The projected costs of long-term geological storage depositories for nuclear waste run from less than half a billion in Slovenia and Croatia to over €20 billion in France, the report says. Total waste management costs (for spent fuel and other nuclear waste streams) will add up to an estimated €142 billion by 2050. That equates to €3.23 per MWh, and the EC report notes that that figure is more than double the estimate of other recent studies.

France will be the only country to operate reprocessing facilities after 2018 (when those in the UK are shut down). The report states that the future of recycled nuclear fuel is limited by the lack of fast-breeder reactors, more safety requirements, a higher risk of proliferation, lower competitiveness, and the fact that it still requires a final waste depository.

The report states that given "the ageing status of the European reactors, the capability of the industry and regulators to develop safe and cost effective decommissioning programs will determine to a great extent the future of nuclear commercial power in Europe". The EC comes up with a total cost of €126 billion for decommissioning out to 2050.

Estimates of decommissioning costs per unit also vary "significantly" between Member States – €0.20 billion in Finland, €0.32 billion in France, €0.85 billion in the UK, €1.06 billion in Germany, and €1.33 billion in Lithuania.

Decommissioning experience is scarce: although 89 reactors had been permanently closed in Europe as of October 2015, only three had been fully decommissioned (all of them in Germany).

Of the €268 billion needed for waste management and decommissioning in the EU by 2050, €150 billion is in the bank.

Energy Post notes some gaps in the draft EC report: "There are a few other things the draft PINC does not (yet) do. It does not advise on the involvement of foreign firms in supposedly strategic energy projects (e.g. China in Hinkley Point C). It does not draw lessons from recent upheavals in the nuclear industry (e.g. Areva's bankruptcy). It does not tackle liability, although a former PINC suggested setting up a harmonised system of liability and financial mechanisms in case of an accident. And finally, it does not discuss harmonising strategies for decommissioning funds – also suggested in the former PINC – beyond proposing a European Centre of Excellence."

1. Sonja van Renssen, 2 Feb 2016, 'Exclusive: EU paints challenging picture of Europe's nuclear future',

2. WNN, 9 Jan 2014, 'Policies hold European nuclear steady',