Abstracts - VGB PowerTech Journal 5/2017

Flexible operation of nuclear power plants – first steps for paradigm change worldwide?

Dr.-Ing. Tatiana Salnikova

The motivation for going flexible for a Nuclear Power Plant (NPP) can vary significantly according to the regional context. For some NPPs, several relevant measures for flexible operation are implemented and well-proven. For others, flexible operation is still not preferable and some actions are even not authorized, e. g. remote secondary control by the grid dispatcher. [more...]

Cyber security in nuclear power plants and its portability to other industrial infrastructures

Sébastien Champigny, Deeksha Gupta, Venesa Watson and Karl Waedt

Power generation increasingly relies on decentralized and interconnected computerized systems. Concepts like “Industrial Internet of Things” of the Industrial Internet Consortium (IIC), and “Industry 4.0” find their way in this strategic industry. Risk of targeted exploits of errors and vulnerabilities increases with complexity, interconnectivity and decentralization. Inherently stringent security requirements and features make nuclear computerized applications and systems a benchmark for industrial counterparts seeking to hedge against those risks. Consequently, this contribution presents usual cyber security regulations and practices for nuclear power plants. It shows how nuclear cyber security can be ported and used in an industrial context to protect critical infrastructures against cyber-attacks and industrial espionage.

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Retrofitting a spent fuel pool spray system for alternative cooling as a strategy for beyond design basis events

Christoph Hartmann and Zoran Vujic

Due to requirements for nuclear power plants to withstand beyond design basis accidents, including events such as happened in 2011 in the Fukushima Daiichi Nuclear Power Plant in Japan, alternative cooling of spent fuel is needed. Alternative spent fuel cooling can be provided by a retrofitted spent fuel pool spray system based on the AP1000 plant design. As part of Krško Nuclear Power Plant’s Safety Upgrade Program, Krško Nuclear Power Plant decided on, and Westinghouse successfully designed a retrofit of the AP1000 plant spent fuel pool spray system to provide alternative spent fuel cooling. The spent fuel pool spray system will be installed inside and outside the Fuel Handling Building. For diverse water supply, sources such as the fire protection system and river water were considered and chosen by Krško Nuclear Power Plant. The system has a robust design that employs local measurements and indicators and does not require electrically driven components. The spent fuel pool spray system is planned to be installed by the end of 2017.

Decommissioning – Success with competent staff and preparation

Jörg Klasen, Rolf Schulz and Oliver Wilhelm

The decommissioning of a nuclear power plant poses a significant challenge for the operating company. The business model is turned upside down and a working culture developed for power operation has to be adapted while necessary know-how for the upcoming tasks has to be built up. The trauma for the employees induced by the final plant shut-down has to be considered and respected. The change of working culture in the enterprise has to be managed and the organization has to be prepared for the future. Here the methods of Change-Management offer a systematic and effective approach. Confidence in the employee´s competencies is one of the key success factors for the change into the future.

Numeric determination and validation of neutron induced radioactive nuclide inventories for decommissioning and dismantling of light water reactors

Peter-W. Phlippen, Luc Schlömer, Roger Vallentin, Bernard Lukas and Stefan Palm

The deconstruction of nuclear power plants requires project planning and budgeting both during the project and in advance, as well as the secured provision of financial and human resources. When a facility is free from irradiated fuel, the reactor pressure vessel with the nuclear components as well as the biological shield determine the activity inventory of the facility, which almost exclusively consists of activated radionuclides located in the respective structures. Knowledge of the activity distribution and nuclide vectors of the involved components is of vital importance for deconstruction planning. In this context, the development of a computation procedure is described coupling the Monte Carlo method for the determination of neutron flux densities with a procedure to perform activation calculations for the determination of nuclide vectors. For this purpose, detailed knowledge of the material composition, particularly the trace-element concentrations of nitrogen and cobalt in steel and additionally of europium and caesium in concrete structures, considerably impacts the accuracy of the calculated activities. Extensive validation using data collected from various reactor facilities, such as nuclide activities, neutron flux densities, and neutron and gamma dose rates, demonstrates the reliability of the computed nuclide distributions showing ratios of computed over measured values of typically between 0.9 and 3. The practicality of the developed method as well as the convenient use of the results have already been demonstrated analysing several German BWR and PWR facilities and developing packaging strategies based on the produced results.

Clearance measurement for waste ­concerning contained radioactivity

Marina Sokcic-Kostic and Roland Schultheis

Clearance measurements are always a compromise between requirements of the measurement tech­nology and economic boundary conditions. ­Depending on the quantity and the type of waste, different solutions are obtained. For large volumes of more or less homogeneous waste, the conveyor belt method is the biggest favorite, which has ­already proved its suitability in practice. This is ­important, because numerous nuclear power ­stations are being decommissioned in Germany in the coming years and large quantities of waste will be arising. For some applications, e.g. Tritium or C-14, satisfying solutions either do not exist or are currently in the development stages. There is still great potential for the development of clearance methods.

Nuclear power economics

Ian Emsley and Jonathan Cobb

Many countries recognize the substantial role which nuclear power has played in providing ­energy ­security of supply, reducing import dependence and reducing greenhouse gas and polluting emissions. Nevertheless, as such considerations are far from ­being fully accounted for in liberalized or ­deregulated power markets, nuclear plants must demonstrate their viability in these markets on commercial ­criteria as well as their lifecycle advantages. Nuclear plants are operating more efficiently than in the past and unit operating costs are low relative to those of alternative generating technologies. The political risk facing the economic functioning of nuclear in a number of countries has increased with the imposition of nuclear-specific taxes that in some cases have deprived operators of the economic ­incentive to continue to operate existing plants.

What people really think about nuclear energy


Nuclear power is a reliable, baseload, low-carbon energy source that can contribute to the fight against climate change. It is also competitive and can help reduce energy dependency. It is vital that politicians take the lead and implement bold decisions regarding the energy mix. Developments in Finland and the UK show that if the political decision to include nuclear in the energy mix is taken and information is communicated in an open, inclusive and democratic way, people tend to become more favourable to nuclear power. The March 2011 accident at the Fukushima-Daiichi nuclear plant in Japan had an impact on public opinion towards nuclear power. Yet the results of opinion polls carried out throughout Europe after the accident show that opinion is polarised and country specific.

Operating experience with nuclear power plants 2016

VGB PowerTech

The VGB Technical Committee “Nuclear Plant Operation” has been exchanging operating experience about nuclear power plants for more than 30 years. Plant operators from several European countries are participating in the exchange. A report is given on the operating results achieved in 2016, events important to plant safety, special and relevant repair, and retrofit measures from Germany (Part I), Belgium, Finland, the Netherlands, Switzerland, and Spain (Part II).

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