atw - May 2015

Safe Long-Term Operation of RPV
Improve Reactor Recirculation Pump Sealing 
Fire-Protection Concept Adaptation 
Reprocessing and Recycling for Research Reactor Fuel
NPP Operation 2014

Why the Risks of Nuclear are “Greatly Exaggerated”

NucNet

Environmentalist Bruno Comby, founder of the lobby group Environmentalists For Nuclear, says the anti-nuclear lobby has transformed a very safe energy source into a huge problem by distorting reality. He spoke to NucNet’s Lubomir Mitev about risk, radiation and the ‘problem’ of nuclear waste.

Bruno Comby trained as a nuclear engineer at the Ecole Polytechnique and Ecole Nationale Supérieure de Techniques Avancées de Paris. He established Environmentalists For Nuclear in 1996.

Towards Safe Long-Term Operation of Reactor Pressure Vessels

Jenny Roudén, Hieronymus Hein, Johannes May, Tapio Planman, Patrick Todeschini, Milan Brumovsky, Antonio Ballesteros, Ferenc Gillemot, Rachid Chaouadi, Pal Efsing and Eberhard Altstadt

This publication summarizes the long term operation (LTO) conditions in European NPPs and provides recommendations on reactor pressure vessel (RPV) irradiation surveillance based on the work performed in the Work Package 7 “Surveillance Guidelines” of the LONGLIFE international project. The LONGLIFE project “Treatment of Long Term Irradiation Embrittlement Effects in RPV Safety Assessment” was 50 % funded by the Euratom 7th Framework Programme of the European Commission. Specific scientific and technical issues addressed in this publication are the following:

  • Surveillance standards and procedures.
  • Reuse of tested irradiated surveillance specimens.
  • Transferability of test reactor results to LWR conditions.
  • Extension of RPV irradiation surveillance programmes.
  • Withdrawal scheme for LTO surveillance programmes.

The objective of the surveillance guidelines is to support the potential end-user (utilities, nuclear power plants, research institutes, etc.) in selecting the appropriate strategy and technical approaches for RPV irradiation surveillance for LTO. In this way contributing to a reliable monitoring of long-term irradiation effects in RPV, and supporting the European efforts towards harmonisation of procedures for RPV surveillance and safety assessment in the light of LTO.

Implementation of Multiple Measures to Improve Reactor Recirculation Pump Sealing Performance in Nuclear Boiling Water Reactor Service

Gerard van Loenhout and Jürg Hurni

A modern reactor recirculation pump circulates a large volume of high temperature, very pure water from the reactor pressure vessel back to the core by feeding into multiple stationary jet pumps inside the vessel. Together with the jet pumps, they allow station operators to vary coolant flow and variable pump speed provides the best and most stable reactor power control. A crucial technical problem with a recirculation pump, such as a mechanical seal indicating loss of sealing pressure, may result in a power station having to shut down for repair.

This article describes the sudden increase in stray current phenomenon leading to rapid and severe deterioration of the mechanical end face shaft seal in a reactor recirculation pump. This occurred after the installation of a variable frequency converter replacing the original motor-generator set. This article will also discuss the 2,500 hour laboratory test results conducted under reactor recirculation pump sealing conditions using a newly developed seal face technology recently implemented to overcome challenges when sealing neutral, ultra-pure water. In addition, the article will describe the elaborate shaft grounding arrangement and the preliminary measurement results achieved in order to eliminate potential damages to both pump and mechanical seal.

Newly Released EIA-Law: A Palette of Wishes?

Ulrike Feldmann

The EU-directive on Environmental Impact Assessment (EIA) for certain public and private projects was once again amended in 2014 after controversial discussions, three previous modifications during 1985 and 2010 and an aggregation of all amendments within the EU-EIA-2011/92 directive. This newly released EU-EIA-directive 2014/52/EU (hereinafter RL 2014/52) is published within the EU-official journal EU L 124 p. 1 from 25.04.2014, came into force on 15. May 2014 and has to be adopted into international law until 16.05.2017.

The modifications made are also valid, apart from certain exceptions, for licensing procedures (including decommissioning of nuclear power plants) in the field of nuclear energy, as far as they might have possible, significant environmental effects. The European EIA directive’s 30th “anniversary” on 27.06.2015 raises the question, which substantial changes will come soon along with the newly released EU-EIA law.

All in all it seems like if authorities and industry might get along with the newly released EU-EIA regulations. The responsible Federal Ministry for the Environment is already working on a first preliminary draft. It is under consideration if the EIA-regulation should be submitted additionally, beyond required amendments by EU-law, to a general revision. EIA-law remains exciting.

I.Care.fire – EDP-Supported Dynamic Fire-Protection Concept Adaptation in the Course of Dismantling Nuclear Facilities

Maxi Mummert and Anke Traichel

Through the political resolution to terminate the use of nuclear energy, the number of dismantling projects in the nuclear area will significantly increase in the years to come. In the course of dismantling, the buildings and plant measures for fire protection will change constantly, this means that the existing fire-protection concept of the plant must be subjected to ongoing adaptation. This adaptation is based on preparation of fire load lists and execution of safety analyses. Previously this adaptation was executed manually, this was both time-intensive and personnel-intensive. The transition to EDP-supported fire protection should occur with the aid of adaptive fire-protection design to optimise adaptation of the fire protection. This adaptive fire protection design, with the aid of a software tool, enables electronic recording of the fire load lists, automatic execution of safety analyses and facilitation of dismantling steps relative to fire protection.

Available Reprocessing and Recycling Services for Research Reactor Spent Nuclear Fuel

Sandor Miklos Tozser, Pablo Adelfang, Ed Bradley, Madalina Budu und Mustapha Chiguer

International activities in the back-end of the research reactor (RR) fuel cycle have so far been dominated by the programmes of acceptance of highly-enriched uranium (HEU) spent nuclear fuel (SNF) by the country where it was originally enriched. These programmes will soon have achieved their goals and the SNF take-back programmes will cease. However, the needs of the nuclear community dictate that the majority of the research reactors continue to operate using low enriched uranium (LEU) fuel in order to meet the varied mission objectives. As a result, inventories of LEU SNF will continue to be created and the back-end solution of RR SNF remains a critical issue. In view of this fact, the IAEA, based on the experience gained during the decade of international cooperation in supporting the objectives of the HEU take-back programmes, will draw up a report presenting available reprocessing and recycling services for research reactor spent nuclear fuel. This paper gives an overview of the guiding document which will address all aspects of Reprocessing and Recycling Services for RR SNF, including an overview of solutions, decision making support, service suppliers, conditions (prerequisites, options, etc.), services offered by the managerial and logistics support providers with a focus on available transport packages and applicable transport modes.

“Rückbau 2014” – KWS Congress Regarding Decommissioning and Dismantling at Nuclear Training Power Plant Zwentendorf

Herbert Maaßen

From September 24th to 25th, 2014 the KRAFTWERKSSCHULE E.V. (KWS) held the congress “Rückbau 2014“. This first congress about the deconstruction of nuclear power plants was combined with an exhibition in the fully equipped nuclear training power plant Zwentendorf. The exhibitors had the opportunity to present and test their products in the ambience of a real nuclear power plant, close to original plant components. The visitors got a general overview of the on-site conditions. During the lectures the process of decommissioning and dismantling of a nuclear power plant was described, problems within this process were discussed, and possible solutions were recommended. The congress influenced significantly the dialogue of all parties involved and contributed to an extensive exchange of knowledge and experience.

60th year atw: Human Performance and its Influence on the Safety of Nuclear Installations

Karl-Heinz Berg and Jochen B. Fechner 

Nuclear facilities need to be handled in all safety considerations as „man-machine- system“ as humans considered as liveware are of equally importance ensuring safety as hardware and software. The Federal Minister of the Interior is attempting to give greater focus to this knowledge for the practice of nuclear safety measures. Therefore hardware and software need to be improved according to ergonomic findings and greater importance needs to be issued to the qualification of the operational staff as well as to the qualification of experts consulted by local authorities.

Is a New Dawn on the Horizon for Nuclear in the Land of the Rising Sun?

John Shepherd

Since the start of this year Japan’s Prime Minister Shinzo Abe’s government has clearly been hard at work behind the scenes, with the result that support for nuclear is far from being forced off the political agenda in that country, as we are often led to believe. Indeed, it is worth taking a fresh look at the situation that is now unfolding across the energy sector in Japan.

The most interesting piece of the ‘political jigsaw’ that will make up future energy policy in Japan was provided by the Ministry of Economy, Trade and Industry (METI). The Japan Atomic Industrial Forum (JAIF) reported that METI, in its new strategic energy plan, aims to increase the level of renewables in the national energy mix to more than 20 percent by 2030. In terms of “baseload” power sources, including nuclear, hydropower, coal-fired plants and geothermal, METI and Abe’s governing Liberal Democratic Party want to set their contribution to the energy mix at about 60 % of the total. JAIF points out that given that it is difficult to substantially increase hydro, coal-fired and geothermal, nuclear power may eventually settle in at more than 20 %.

In the land of the rising sun it seems there may yet be a new dawn approaching for nuclear. There is still a long way to go. The path ahead will not be an easy one and both government and industry will need to tread with the utmost care – not least in taking into account public opinion.

 

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