atw - June/July 2018

_AMNT 2018: Opening Address
_TESPA-ROD Code Prediction of the Fuel Rod Behaviour During Long-term Storage
_Safery Assessment of the Research Reactors FRM II and FR MZ
_The Unnoticed Loss of the Carbon-free Generation in the Unites States
_Radiological Characterization of High-level Radioactive Waste

Poland Faces Delays and Decisions as It Makes Ambitious Plans to Go Nuclear


Poland has drawn up ambitious plans to build up to 6,000 MW of nuclear generating capacity, potentially at two sites, by the late 2030s or early 2040s. But the government is yet to take a final decision and the deadline has pushed back several times, with plans hampered by changes in government, problems putting in place the right domestic legislation and the need to find the right financing model. Poland needs nuclear because of its low carbon footprint and as a way to decrease the country’s carbon emissions. Poland is no newcomer to nuclear technology. The Polish National Centre for Nuclear Research (NCBJ) has operated a research reactor at Swierk. In 1971 the government made its first binding decision to build a nuclear plant. The project was formally scrapped in 1990.

49th Annual Meeting on Nuclear Technology (AMNT 2018): Opening Address

Ralf Güldner

As in other years, DAtF and the German Nuclear Society (KTG), offer a comprehensive program with their 49th Annual Meeting on Nuclear Technology, giving insights into many aspects of nuclear technology and contributing to the international exchange of knowledge and experience in industry, research, politics and administration. In keeping with long-standing tradition, even in the year preceding its 50th anniversary, on 7 and 8 May 2019 in Berlin, the AMNT remains the only conference in Germany, and one of the few in Europe, that combines all the issues surrounding nuclear technology under one roof and is dedicated to every sector of the industry.

TESPA-ROD Code Prediction of the Fuel Rod Behaviour During Long-term Storage

Heinz G. Sonnenburg

The fuel rod code TESPA-ROD is applicable to LOCA transients and RIA transients. Recently, code models have been implemented in order to predict the transitional fuel rod behaviour during long-term storage. In particular modelling for both long-term fuel swelling and associated helium gas release have been implemented. First TESPA-ROD code predictions for the long-term transient, including wet storage, drying procedure and dry storage indicate gap closure between fuel and cladding. Thus, stress level in the cladding may depend on both the internal fission gas pressure and the fuel/cladding mechanical interaction.

New Build Projects Abroad – A Challenge for Regulation

Christian Raetzke

Numerous reactors are under construction or in the planning stage worldwide. However, compared to the situation a few decades ago, when the majority of the plants in operation today were built, the project models and boundary conditions are much more diverse, so that traditional models of regulation, approval and supervision (regulation) sometimes reach their limits. The article provides examples of new challenges. Regulation must find new answers to the challenges. However, it must not ignore the proven principles and instruments in order to ensure nuclear safety.

Safety Assessment of the Research Reactors FRM II And FR MZ After the Fukushima Event

 Axel Pichlmaier, Heiko Gerstenberg, Anton Kastenmüller, Christian Krokowski, Ulrich Lichnovsky, Roland Schätzlein, Michael Schmidt, Christopher Geppert, Klaus Eberhardt and Sergei Karpuk

After the events at the Fukushima-I nuclear power plant (NPP) in 2011 the Reaktorsicherheitskommission (RSK) has carried out an overall assessment of the German nuclear fleet with respect to extreme (beyond design base) events. This paper deals only with the research reactors (RR) FRM II (Garching) and FR MZ (Mainz). The findings of the RSK, its recommendations and their status of implementation will be presented.

Decommissioning of Germany’s First Nuclear Reactor

Ulrich Lichnovsky, Julia Rehberger, Axel Pichlmaier and Anton Kastenmüller

FRM started operating in 1957 as the first nuclear reactor in Germany. Reactor operation ended in 2000. Licensing procedures for the deconstruction and dismantling of the reactor started in 1998. In 2014 the Technical University of Munich (TUM) was granted the license to decommission the reactor. The article describes the (long) way to the license for dismantling of the reactor and gives a short overview of the current state of the decommissioning project. Results of the (pre-)licensing stage are presented: disposal of spent nuclear fuel (SNF) and preparation of the safety report containing details on fire protection, radiological characterization (neutron activation and contamination), waste management and safety analysis. With regard to the current state of the project we will discuss: clearance of material and current obstacles.

While You were Sleeping: The Unnoticed Loss of Carbon-free Generation in the United States

Chris Vlahoplus, Ed Baker, Sean Lawrie, Paul Quinlan and Benjamin Lozier

The United States has embarked on actions to combat climate change by putting a focus on lowering the carbon emissions from the electric generation sector. A pillar of this approach is to promote the greater use of renewable resources, such as wind and solar. The past decade has seen significant growth in carbon-free energy from wind and solar. Generation from these resources reached 333,000 GWh in 2017. However, unbeknownst to many who care about climate change, most of the progress made to date through renewables is at significant risk due to the loss or potential loss of more than 228,000 GWh of nuclear carbon-free generation.

German Secretarial Management ISO/TC 85/SC 6 Reactor Technology

Janine Winkler and Michael Petri

On behalf of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) and represented by the Office of the Nuclear Safety Standards Commission (KTA), DIN has taken over the Secretariat of ISO/TC 85/SC 6 Reactor technology in conjunction with China in 2018. The new role provides an opportunity to increase German participation and influence in the field of International Standardization, for instance via conversion of German Industrial and KTA Standards into International Standards. This demonstrates that Germany is willing to actively participate in the ongoing efforts to increase Nuclear Safety in the peaceful use of Nuclear Energy.

Thermal Hydraulic Analysis of the Convective Heat Transfer of an Air-cooled BWR Spent Fuel Assembly

Christine Partmann, Christoph Schuster and Antonio Hurtado

Since the reactor accident in Fukushima Daiichi, the vulnerability of spent fuel pools (SFP) is more focused in nuclear safety research. This paper presents the experimental findings about the convective heat transfer of a boiling water reactor (BWR) spent FA under the absence of water. These studies are performed within the joint project SINABEL that is funded by the German Federal Ministry of Education and Research to investigate the thermal hydraulics of selected accident scenarios in SFP experimentally and numerically.

Further Development of a Thermal-Hydraulics Two-Phase Flow Tool

Verónica Jáuregui Chávez, Uwe Imke, Javier Jiménez and V.H. Sánchez-Espinoza

The numerical simulation tool TWOPORFLOW is under development at the Institute for Neutron Physics and Reactor Technology (INR) of the Karlsruhe Institute of Technology (KIT). TWOPORFLOW is a thermal-hydraulics code that is able to simulate single- and two-phase flow in a structured or unstructured porous medium using a flexible 3-D Cartesian geometry. The main purpose of this work is the extension, improvement and validation of TWOPORFLOW in order to simulate the thermal-hydraulic behavior of Boiling Water Reactor (BWR) cores.

Special Features of Measurement for the Radiological Characterization of High-level Radioactive Waste

Marina Sokcic-Kostic and Roland Schultheis

In nuclear power plants occasionally highly radioactive waste is produced, such as fragments of defective fuel elements or filters from hot cells. NUKEM Technologies Engineering Services has designed and implemented waste treatment options for such waste in projects that characterise high-level radioactive waste and condition it in accordance with the requirements for long-term storage. This also includes a volume reduction to minimize future storage costs. The focus of this article is on the measurement of highly active waste and its implications.

Confidence in Nuclear Safeguards at Risk as Trump Quits One Deal to Pursue Another

John Shepherd

Confidence in nuclear safeguards at risk as Trump quits one deal to pursue another. By the time you sit down to read this article, Donald Trump and Kim Jong Un may have had an historic sit-down of their own – in fact the first meeting between a sitting US president and a leader of North Korea.


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