atw - April 2018

_Heat Transfer Systems for Novel Nuclear Power Plant Designs
_Safety Research of GEN IV Reactors
_Numerical Analysis of MYRRHA Project
_Passive Heat Removal Systems Research
_‘Ugly’ Nuclear Deserves a Political Makeover

Euratom: Industry Softens Stance as Government Lays Out Plans for Transition


The UK’s nuclear industry has welcomed a government commitment to continuity with existing arrangements with Euratom, Europe’s nuclear safety and research watchdog, a softening of its earlier stance that the UK needed to stay in the group to protect vital nuclear research and new-build projects, and to make sure access to nuclear fuel and medical isotopes is not disrupted. The next phase of discussions will focus on the UK’s future relationship with Euratom. Specific objectives include a close association with the Euratom Research and Training Programme, including the Joint European Torus (JET) and the International Thermonuclear Experimental Reactor (ITER) projects.

Heat Transfer Systems for Novel Nuclear Power Plant Designs

Sebastian Vlach, Christoph Fischer and Herman van Antwerpen

This article focuses on designing or modifying heat exchangers found in the auxiliary systems of any power plant. The basic premise is to show that the software provides a one-stop solution for designing many types of heat transfer systems, where the interaction between various loops connected by heat exchangers can be assessed. The nuclear power plant industry is addressed as the quality control in the development of the software makes it most suitable for nuclear related applications. Moreover, the software discussed has the capability to do contaminant tracing, which could be very useful for nuclear contamination studies in designing specialized ventilation systems. To highlight the versatility of the software network approach it will be shown how to model any setup and kind of heat exchanger such as plate, tube-in-tube, liquid/gas, finned tube etc. Additionally, the Koeberg pressurized water reactor  steam generator comparison and the THTR steam generator comparison are shown as examples.

Experimental and Analytical Tools for Safety Research of GEN IV Reactors

G. Mazzini, M. Kyncl, Alis Musa and M. Ruscak

Current research on nuclear safety in the world, in addition to supporting existing nuclear power plants is focused on the more detailed aspects of the new reactors. The new generation reactors are expected inter alia to use innovative types of fuel and new types of coolants, such as e.g. Super-Critical Water (SCW), supercritical CO2, liquid metals, fluoride salts or high-temperature Helium. The paper will describe new experimental infrastructure build recently in Research Centre Řež under the SUSEN (Sustainable Energy) project and available analytical tools for supporting safety research of GEN IV reactors. Two experimental loops – SCWL (Supercritical Water Loop) and HTHL (High Temperature Helium Loop) will serve as in-pile loops in the active core of the research reactor LVR-15. The paper provides examples of analyses made using codes ATHLET (supercritical water) and TRACE (high temperature He) illustrating process of their assessment and practical use. 

Numerical Analysis of MYRRHA Inter-wrapper Flow Experiment at KALLA

Abdalla Batta and Andreas G. Class

The MYRRHA reactor, which is developed at SCK-SCN in Belgium, represents a multi-purpose irradiation facility. Its prominent feature is a pool design with the nuclear core submerged in liquid metal lead bismuth. During transients between normal operation and accident conditions decay heat removal is ensured by forced and natural convection, respectively. The flow in the gap between the fuel assemblies plays an important role in limiting maximum temperatures which should not be exceeded to avoid core damage. Due to the scarce database, within the Horizon 2020 – research and innovation framework program of the EU, the SESAME project was established to develop and validate advanced numerical approaches, to achieve a new or extended validation base and to establish best practice guidelines including verification & validation and uncertainty quantification. In particular the current work supports the inter-wrapper flow experiment at KALLA.

Heat Balance Analysis for Energy Conversion Systems of VHTR

SangIL Lee, YeonJae Yoo, Deok Hoon Kye, Gyunyoung Heo, Eojin Jeon and Soyoung Park

VHTR(Very High Temperature Gas Reactor) with helium used as a coolant can easily produce heat required in high-temperature thermochemical process, and because of low heat output density, the possibility of core melting is low. In this study, provided that VHTR is located in the primary system, the heat conversion system will be discussed in which hydrogen production and power supply are possible. In order to control the ratio between power and hydrogen production, the helium flowing through nuclear reactor is made to pass through heat exchanger for hydrogen production and steam generator or heat exchanger. This study proposes the whole heat conversion system model, and carries out thermodynamic feasibility calculation according to major design variable at each point and sensitivity analysis for efficiency optimization.

Information Requirements Versus Confidentiality Obligations – Extension of the In-Camera Procedure Planned

Tobias Leidinger

The justified right of the public to detailed information on a project requiring nuclear licensing is opposed by the state’s interest in effective protection of sensitive data. This conflict is manifested in licensing procedures but also at court. The differentiated legal provisions that regulate the balancing of these conflicting interests are now to be supplemented by a further facet: An expanded in-camera trial at court. According to the coalition agreement of 7 February 2018, the regulation is to take place in the current 18th legislative period.

CFD Modeling and Simulation of Heat and Mass Transfer in Passive Heat Removal Systems

Amirhosein Moonesi, Shabestary, Eckhard Krepper and Dirk Lucas

The CFD-modelling and simulation of condensation inside passive heat removal systems are presented. Designs of future nuclear boiling water reactor concepts are equipped with emergency cooling systems which are passive systems for heat removal. The emergency cooling system consists of slightly inclined horizontal pipes which are immersed in a tank of subcooled water. The focus of the project is on detection of different morphologies such as annular flow, stratified flow, slug flow and plug flow and also modeling of the laminar film which is occurring during the condensation near the wall. 

The Decommissioning of the ENEA RB3 Research Reactor in Montecuccolino

F. Rocchi, C. M. Castellani, A. Compagno,I. Vilardi, R. Lorenzelli and A. Rizzo

The ENEA RB3 reactor was a 100 Wth research installation owned and operated by ENEA, in its center of Montecuccolino near Bologna, from 1971 to 1989. In 1989, the RB3 reactor was shut down, and in the late 2010 ENEA received by ministerial decree the authorization to its dismantling, with the aim of reaching the “green field” status. This paper presents the three main pillars of the decommissioning of RB3, namely the strategy and methods for the dismantling, the strategy and methods for the radiological characterization of the building, and finally the strategy and methods for the radiological characterization of the site.

Irradiation Tests of a Flat Vanadium Self-Powered Detector with 14 MeV Neutrons

Prasoon Raj and Axel Klix

Self-powered detector (SPD) represents a class of neutron and gamma monitoring instruments used in the fission reactor cores worldwide. This detector has inherent advantages of functioning without a bias voltage, simple measurement scheme, compactness, ease of maintenance, and high reliability. We are studying SPD for application as flux monitors in the European test blanket modules (TBM) of ITER, fusion reactor under construction in southern France.

Nanofluid Applied Thermo-hydrodynamic Performance Analysis of Square Array Subchannel Under PWR Condition

Jubair Ahmed Shamim and Kune Yull Suh

Efficient engineered design of heat transfer and fluid flow with enhanced heating or cooling requires two pivotal aspects that must be taken into consideration for extracting thermal energy from nuclear fission reactions in order to save energy, reduce process time, raise thermal rating and increase the operating life of a reactor pressure vessel. Hence, one of the major challenges in designing a new nuclear power plant is the quantification of the optimal flow of coolant and distribution of pressure drop across the reactor core. Recently, nanofluid has gained much renewed attention as a promising coolant for pressurized water reactors (PWRs) due to its enhanced thermal capabilities with least penalty in pressure drop. 

Czechs and Balances and Why ‘Ugly’ Nuclear Deserves a Political Makeover

John Shepherd

As if Europe does not have enough on its plate to deal with at the moment – politically and economically just for starters – could Brussels be on a collision course with the Czech government over the countries plans to expand nuclear energy?

There is certainly friction over the issue between Prague and the European Commission (EC), to put it mildly. But why?

The veteran head of the Czech Republic’s State Office for Nuclear Safety, Dana Drábová, last month accused other EU member states of “pressurising” Prague over the early closure of its oldest nuclear reactor units.


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