atw - August/September 2018

_Akademik Lomonosov: Preparation for Premiere in Full Swing
_Westinghaouse EnCore Accident Tolerant Fuel
_Neutron Flux Fluctuation in PWR
_Coated Ceramic Honeycomb Type Passive Autocatalytic Recombiner
_Young Scientists Workshop

A Stark Warning to Trump on China, Russia and the ‘Crisis’ Facing US Nuclear Industry

NucNet, David Dalton

The US has the largest number of nuclear plants in the world – 99 in commercial operation at the time of writing – but its global leadership position is said to be declining as efforts to build a new generation of reactors have been plagued by problems, and aging plants have been retired or closed in the face of economic, market, and financial pressures. A recent report by the Atlantic Council issued a stark warning, arguing that the US nuclear energy industry is facing a crisis that the Trump administration must immediately address as a core part of its “all of the above” energy strategy.

Akademik Lomonosov: Preparations for Premiere in Full Swing

Roman Martinek

At the end of July 2018, the loading of the floating power unit Akademik Lomonosov with nuclear fuel started in Murmansk. This is one of the key stages of the project, which as of today has no analogues in the world. In 2019, the power unit will begin to supply local population and industrial facilities in North-Eastern Siberia with heat and electricity. The project is expected to open up opportunities for the mass production of floating nuclear power plants – a number of countries have already voiced their interest. The Akademik Lomonosov is intended for  providing energy to remote industrial facilities, port cities, as well as gas and oil platforms located on the high seas.

Nuclear Phase-out Last Act? Are the New Compensation Regulations for Frustrated Expenses in Accordance with the Constitution?

Tobias Leidinger

Shortly before it was passed, the legislature reacted to the constitutional deficiencies which the Federal Constitutional Court (BVerfG) objected to in its judgment of 6 December 2016 on the nuclear phase-out (BVerfGE 143, 246) and for which a constitutional situation had to be established by 30 June 2018. However, the newly created compensation regulations in the 16th amendment to the Atomic Energy Act raise new legal questions, especially those relating to their constitutionality.


Westinghouse EnCore® Accident Tolerant Fuel

Gilda Bocock, Robert Oelrich and Sumit Ray

The development and implementation of accident tolerant fuel (ATF) products, such as Westinghouse’s EnCore® Fuel, can support the long-term viability of nuclear energy by enhancing operational safety and decreasing energy costs. The first introduction of Westinghouse EnCore Fuel into a commercial reactor is planned for 2019 as segmented lead test rods (LTRs) utilizing chromium-coated zirconium cladding with uranium silicide (U3Si2) pellets. The EnCore Fuel lead test assembly (LTA) program, with LTAs planned for 2022 insertion, will introduce silicon carbide/silicon carbide composite cladding with U3Si2 pellets.

Analyses of Possible Explanations for the Neutron Flux Fluctuations in German PWR

Joachim Herb, Christoph Bläsius, Yann Perin, Jürgen Sievers and Kiril Velkov

During the last 15 years the neutron flux fluctuation levels in some of the German PWR changed significantly. During a period of about ten years, the fluctuation levels increased, followed by about five years with decreasing levels after taking actions like changing the design of the fuel elements. The increase in the neutron flux fluctuations resulted in an increased number of triggering the reactor limitation system and in one case in a SCRAM. Several models based on single physical effects are used to simulate the neutron flux. Each of these simple models can reproduce some of the characteristics of the observed neutron flux fluctuations.

Detailed Measurements and Analyses of the Neutron Flux Oscillation Phenomenology at Kernkraftwerk Gösgen

G. Girardin, R. Meier, L. Meyer, A. Ålander and F. Jatuff

Recent investigations on measured neutron flux noise at the Kernkraftwerk Gösgen-Däniken are summarised. The NPP in operation since 1979 is a German KWU pre-KONVOI, 3-Loop PWR with a thermal power of 3,002 MWth (1,060 MWe). In a period of approx. 7 cycles from 2010 to 2016, an increase of the measured neutron noise amplitudes in the in- and out-core neutron detectors has been observed, although no significant variations have being detected in global core, thermohydraulic circuits or instrumentation parameters. Verifications of the instrumentation were performed and it was confirmed that the neutron flux instabilities increased from cycle to cycle in this period. In the last two years, the level of neutron flux noise remains high but seems to have achieved a saturation state.

Effects of Airborne Volatile Organic Compounds on the Performance of Pi/TiO2 Coated Ceramic Honeycomb Type Passive Autocatalytic Recombiner

Chang Hyun Kim, Je Joong Sung, Sang Jun Ha and Phil Won Seo

Ensuring the containment integrity during a severe accident in nuclear power reactor by maintaining the hydrogen concentration below an acceptable level has been recognized to be of critical importance after Fukushima Daiichi accidents. Although there exist various hydrogen mitigation measures, a passive autocatalytic recombiner (PAR) has been considered as a viable option for the mitigation of hydrogen risk under the extended station blackout conditions because of its passive operation characteristics for the hydrogen removal. As a post-Fukushima action item, all Korean nuclear power plants were equipped with PARs of various suppliers. The capacity and locations of PAR as a hydrogen mitigation system were determined through an extensive analysis for various severe accident scenarios.

49th Annual Meeting on Nuclear Technology (AMNT 2018): Young Scientists Workshop

Jörg Starflinger

During the Young Scientists Workshop of the 49th Annual Meeting on Nuclear Technology (AMNT 2018), 29 to 30 May 2018, Berlin, 13 young scientists presented results of their scientific research as part of their Master or Doctorate theses covering a broad spectrum of technical areas. Vera Koppers, Katharina Amend and Maria Freiria were awarded for their presentations by the jury.

Heuristic Methods in Modelling Research Reactors for Deterministic Safety Analysis

Vera Koppers and Marco K. Koch

A new method for rapid and reliable modelling of research reactors for deterministic safety analysis is presented. A rule-based software system is being developed to support the modelling process in ATHLET for selected research reactor types in the light of limited available data. The fundamental elements of the input deck are generated automatically by few input data necessary.

Development and Validation of a CFD Wash-Off Model for Fission Products on Containment Walls

Katharina Amend and Markus Klein

The research project aims to develop a CFD model to describe the run down behavior of liquids and the resulting wash-down of fission products on surfaces in the reactor containment. The paper presents a three-dimensional numerical simulation for water running down inclined surfaces coupled with an aerosol wash-off model and particle transport using OpenFOAM. The wash-off model is based on Shields criterion. A parameter variation is conducted and the simulation results are compared to experiments.

A Preliminary Conservative Criticality Assessment of Fukushima Unit 1 Debris Bed

María Freiría López, Michael Buck and Jörg Starflinger

A conservative criticality evaluation of Fukushima Unit 1 debris bed has been carried out. In order to obtain a multi-dimensional criticality map, parameters, such as debris size, porosity, particle size, fuel burnup, water density and boration were varied. As a result, safety parameter ranges where recriticality can be excluded have been identified. It was found that most of the possible debris would be inherently subcritical because of its porosity and 1600 ppm B would ensure subcriticality under any conditions.

49th Annual Meeting on Nuclear Technology (AMNT) Key Topic | Outstanding Know-How & Sustainable Innovations

Christian Raetzke

The report summarises the presentations of the Focus Session International Regulation | Radiation Protection: The Implementation of the EU Basic Safety Standards Directive 2013/59 and the Release of Radioactive Material from Regulatory Control presented at the 49th AMNT 2018, Berlin, 29 to 30 May 2018.

Report: GRS Workshop “Safety of Extended Dry Storage of Spent Nuclear Fuel”

Klemens Hummelsheim, Florian Rowold and Maik Stuke

Conference report on the GRS Workshop “Safety of Extended Dry Storage of Spent Nuclear Fuel”, 6 to 8 June 2018.

Why do We Allow Nuclear to Take the ‘Silly Season’ Media Heat?

John Shepherd

The time of year always means all manner of weird and wonderful stories finding their way into the news. For the nuclear industry, the hot spell fanned the media flames of an old anti-nuclear favourite, as it became clear operations at some nuclear power plants were being halted temporarily to comply with restrictions that prevent cooling water further heating local rivers and waterways. It’s a question why the nuclear community does not use the time of year to communicate their important and interesting topics.


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