The lead-cooled fast reactor (LFR) is one of the concepts of the Generation IV reactorsystems. There are some issues that have to be solved before a research orcommercial LFR can be built. The objective of this thesis was to identify these keyissues and analyse them by studying results from previous research: choice of fuel,corrosion on structural materials and corrosion/erosion on pumps.The major fuel candidates for the LFR are MOX fuel (Mixed OXide fuel), metallic fuel,nitride fuel and carbide fuel. Nitride fuel has desirable properties but its production ismore difficult than for MOX fuel.Most of today’s commercial steels are not corrosion resistant at higher temperaturesbut they could possibly be used for an LFR test demonstrator with an operatingtemperature lower than 450 ºC. A new type of steel called oxide dispersionstrengthened (ODS) steel and a new ceramic material MAXTHAL both showpromising corrosion resistance even at higher temperatures.By controlling the oxygen concentration a protective oxide film is produced. Flowingliquid coolant causes erosion and wears down the oxide film. Pumps are exposed tocoolant velocities of 10-15 m/s causing both erosion and corrosion. There is nosolution today, but MAXTHAL shows promising results in tests with liquid lead of lowvelocity. There are also other issues unsolved, such as irradiation damage onstructural materials, thus more research is needed.Economic and political aspects were not covered in this study. This thesis work wasperformed at Vattenfall Research and Development AB.

The goal of this work is to investigate the capabilities of two different commercial codes, OpenFOAM and ANSYS CFX, to predict forced convection heat transfer in low Prandtl number fluids and investigate the sensitivity of these predictions to the type of code and to several input parameters.The goal of the work is accomplished by predicting forced convection heat transfer in two different experimental setups with the codes OpenFOAM and ANSYS CFX using three different turbulence models and varying the input parameters in an extensive sensitivity analysis. The computational results are compared two the experimental data and analyzed for qualitative and quantitative parameters, such as shape of velocity and temperature profiles, thickness of the boundary layers and wall temperatures.The results show that predictions of the temperature and velocity field are generally sufficient to good, however, the sensitivity especially to the turbulent Prandtl number has to be taken into account when computing forced convection heat transfer in low Prandtl number fluids. The results also show that methods applied to OpenFOAM cannot directly be applied to ANSYS CFX. / <p>QC 20130531</p> / GENIUS

In this work the susceptibility of Fe-10Cr-4Al steel to liquid metal embitterment (LME)in low oxygen environment was investigated. slow strain rate testing (SSRT) wereconducted on 10-4 FeCrAl steel in a stagnant lead from 340-480◦C, lead-bismutheutectic (LBE) from 140-450◦C and lead-bismuth mixture at 375◦C with increasingbismuth content from 0.1wt%-40wt%. The results showed that in the stagnant leadenvironment the FeCrAl steel showed no sign of LME with all samples being subjectedto around 25% strain before final break. In LBE the samples were affected by LMEespecially at 350-400◦C. The total elongation to failure reduced in LBE from 25%to 13.1% and a ductility trough from 190-400◦C was observed. In the lead-bismuthmixture there was a reduction in ductility at 5wt% going from 25% to 20% totalelongation, at 15wt% going from 20% to 16% total elongation and at 30wt% going from16% to 13% total elongation. / I det här arbetet har stålet Fe-10Cr-4Al känslighet till liquidmetal embrittlemnt(LME)i låga syre miljöer av flytande bly, mellan 340-480 °C, och Bly/Vismut eutektisk (LBE),mellan 140-450 °C, undersökts. En stegvis ökning av Vismut halten i flytande blygenfördes också från 0.1 wt% Bi till 40 wt% Bi med en fast temperatur på 375 °C.Resultaten från dessa experiment visade att i ren bly miljö så visade stålet Fe-10Cr-4Al inga tecken på LME, alla prover gick till brott runt 25% strain. I LBE blev ståletsvårt på verkat av LME, framför allt inom temperaturer intervallet 350-400 °C. Dentotala förlängningen av proverna blev här reducerat från 25% ner till 13.1% och en klarduktilitets tråg mellan 190-400 °C kunde observeras. I experimenten med gradvisökande Vismut halt observerades markanta nedgångar i stålets duktilitet vid 5 wt%Bi då den droppar från 25% till 20% förlängning, nästa dropp observerades vid 15 wt%Bi, 20%-16% och vid 30 wt% Bi med ett reduktion från 16% till 13%.

This master’s thesis deals with usage of burn-up (spent) nuclear fuel in nuclear power plants of next generation – accelerator driven transmutation plants which is produced in current nuclear power plants. This system could significantly reduce the volume of dangerous long-lived radioisotopes and moreover they would be able to take advantage of its great energy potential due to fast neutron spectrum. In the introduction are listed basic knowledge and aspects of spent nuclear fuel along with its reprocessing and the possibility of further use while minimizing environmental impact. As another point detailed description of accelerator driven systems is described together with its basic components. In addition this search is followed by individual chronological enumeration of projects of global significance concerning their current development. Emphasis is placed on SAD and MYRRHA projects, which are used like base for calculations. This last, computational part, deals with the creation of the geometry of subcritical transmutation reactor driven by accelerator and subsequent evaluation which assembly is the most effective for transmutation and energy purposes along with changing of target, nuclear fuel and coolant/moderator.