[en] The behavior of the materials used for designing nuclear reactor cores is necessary to be predicted under severe irradiation and high-temperature regimes with high accuracy. The accumulation of gaseous fission products is of great importance for the performance of the materials. We have summarized the results, obtained by Doppler Broadening of the Annihilation Line (DBAL) technique using a Slow Positron Beam (SPB) of UO2and ZrC implanted by Xe-ions, in order to simulate in core conditions, at different fluences up to 16 -21×10Xe cm. The sensitivity of the DBAL to discriminate single Xe atoms and Xe bubbles is discussed. Common trends in the formation of Xe bubbles as a result of the Xe fluence and/or post-implantation annealing of the studied materials were found. We also report DBAL results on structural modification by ion irradiation in B4C. The DBAL spectroscopy using an SPB is demonstrated to be an excellent complementary technique to SIMS, RBS, and TEM.A project to build an SPB laboratory at the Extreme Light Infrastructure -Nuclear Physics (ELI-NP) in Magurele (Ilfov, Romania) is presented. The Gamma Beam System at ELI-NP is a unique machine which will produce a brilliant gamma beam, with energy up to 19 MeV, by Compton backscattering of laser photons on electrons from a warm LINAC. Part of the time, the gamma beam will be used for pair production in a tungsten converter and, after moderation, slow positrons of high intensity (>106 s-1) will be extracted to form an SPB. As a user dedicated facility, ELI-NP will provide access to scientists interested in condensed matter studies by slow positrons. (authors)

[en] The paper presents a new methodology for a more realistic controlling earthquake evaluation, associated with seismic hazard on a site, characterized by magnitude and epicentral distance, MC and DC. The calculation procedure currently used is based on the RG 1.208 guide, (A Performance-Based Approach to Define the Site-Specific Earthquake Ground Motion, U.S. NRC, March 2007). These values characterize the source-site and are used to choose recorded accelerograms for a site analysis and to develop the ground response spectrum for design earthquake. Introducing control values MC and DC in ground motion prediction equations (used for hazard evaluation) there are obtained acceleration values that strongly differ to the design values, PGA for the design annual probability of exceeding. These two control values are not correlated. The new methodology aims to correlates control values with the design values (seismic hazard-acceleration) from which they have been calculated. (authors)

[en] This paper investigated 230 Alloy (UNS N06230) after some heat-cycling tests. Others common trade names for Alloy 230: Haynes® 230, Inconel® 230 (UNS N06230). The study continues prior tests realized in INR Pitesti concerning utilization of some nickel-based alloys in the heat exchangers and steam generators construction. The thermal cycling consists in heating-cooling successive with some rates in a range temperature. Technical parameters of thermal cycling: 50 & 200 cycles, 25 C°/minute heating-cooling rate, 4501000°C temperature range, and argon working medium. The analysis consisted in metallographic examination (microstructure), Vickers microhardness, and traction tests. The average grain size was determined automatically. The micro hardness was calculated by the relationship of the device technical book. On the Strength-Deformation diagrams were obtained: tensile strength and elongation. The tested samples were compared with the „as received” material. The results showed a good metallographic and mechanical behaviour of Haynes 230 alloy at these thermal-cycling tests. (authors)

[en] The method described in this paper to characterize the drag force on pump case, and on the molten liquid metal, is based on experiments using spinning disks near stationary permanent magnets. In order to verify the results, the experimental results have been compared with the results calculated using the equations from magneto hydro dynamic literature. A software has been also developed. The software is able to compute the drag force generated in the flowing liquid metal, inside the pipe, but it is also able to compute the drag force developed on the pump case. The analytical method implemented is based on calculation of drag force generated in layers. The experiments have been done using aluminium disks and neodymium magnets. Different configurations of magnets positions have been used. (authors)

[en] The motor with transverse magnetic flux consists of a primary part, which is moving and a secondary part which is stationary and does not have any windings. The motor can operate under AC or DC supply. When supplied from an AC source it must be equipped with a capacitor connected in series with the coil. In this case the motor operates on the basis of resonance in an RLC primary circuit. When supplied from a DC source it must be equipped with a controlled switch connected to the primary circuit. In this case it operates as a linear switched reluctance motor. The objectives of the paper were to describe the principle of operations of the LRM motor on the basis of one chosen structure. Equations that describe the electromagnetic energy conversions and different types of switched reluctance motors and their features are discussed. (authors)

[en] Since 1998 SCK•CEN is developing the MYRRHA project as an accelerator driven system (ADS) based on the lead-bismuth eutectic (LBE) as a coolant of the reactor and a material for its spallation target. MYRRHA is a flexible fast-spectrum pool-type research irradiation facility, also serving since the FP5 EURATOM framework as the backbone of the Partitioning & Transmutation (P&T) strategy of the European Commission concerning the ADS development in the third pillar of this strategy. MYRRHA is proposed to the international community of nuclear energy and nuclear physics as a pan-European large research infrastructure in ESFRI to serve as a multipurpose fast spectrum irradiation facility for various fields of research. In this paper, we present the current design of MYRRHA and the updated implementation strategy. (authors)

[en] Transient testing of MYRRHA type fuel started at the TRIGA-ACPR Reactor. MYRRHA is a lead-bismuth cooled fast reactor under development by SCK-CEN. The goal of our project is to develop new testing methodologies and experimental devices for transient tests on Liquid Metal Fast Reactor type fuel, aimed to establish the fuel failure threshold (expressed in energy deposition) for cladding failure due to the Pellet Cladding Mechanical Interaction (PCMI). Based on the reactor physics assessment and the test fuel segment design, the design, fabrication and licensing of a new irradiation rig has been completed. Twenty uranium dioxide test fuel segments have been manufactured at SCK-CEN to be used in the tests. The un-irradiated test segments have been designed such that they resemble, as much as possible, a MYRRHA fuel pin at high burnup level. This is achieved by reducing the pellet-cladding gap size and a modification of the cladding cold-worked fraction. Fuel performance simulations have been carried out to evaluate expected values of energy deposition producing fuel failure. The paper presents a synthesis of the computational and experimental effort carried out, as well preliminary results and conclusions based on the first pulse experiments performed at the TRIGA-ACPR reactor. (authors)

[en] The paper investigates the influence of the hydrogen precipitates (hydrides platelets) on fatigue crack initiation at volumetric flaws on the CANDU pressure tube specimens -Zr-2.5% Nb alloy. Delayed Hydride Cracking (DHC) is the main damaging phenomenon, which can affect the life of CANDU pressure tubes when absorbed deuterium greater than the equivalent hydrogen solubility at the operation temperatures. Some typical volumetric flaws (Debris Fretting Flaw and Bearing Pad Fretting Flaws) were found by in-service inspections and they can promote DHC initiation if they have a sharp flaw at the flaw tip. The fatigue mechanism may induce a small sharp crack at blunt tip flaws and further by DHC mechanism the crack will grow under certain stress-temperature scenarios. Experimental investigations from present paper are based on the fatigue tests in elastic stress range. The specimens were prepared in a typical „C-ring” shape from the circumferential direction of the CANDU pressure tube. Few thermal cycles under constant stress were applied to hydrided specimens to achieve reorientation of hydrides at high stress spot from flaw tip. The mechanical stress analyses of the specimens with flaw were performed by finite element method, and the results are compared with predictions N285.8 Canadian standard methodology. The results can be used for the structural integrity analyses of pressure tubes in CANDU fuel channels subject to periodic inspections at Cernavoda NPP. (authors)

[en] This paper describes a robotic equipment to be integrated into the technology for the in-service investigation and / or the replacement of CANDU 600 reactor fuel channels. This equipment includes a robot part which is remotely operated and moves autonomously inside the pressure tubes. The robot takes samples from the interior surface of the pressure tube for hydrogen concentration determination. If the hydrogen concentrations in a pressure tube are above critical levels it must be closed and then replaced. The use of this remotely operated equipment for routine inspections will reduce the overall radiation exposure of the personnel working in nuclear power plant. In addition, continuous monitoring of the hydrogen concentrations in pressure tubes is undoubtedly an important part of the overall maintenance of a nuclear power plant. This manuscript has relevance by the fact that it is directly related to the safety of both personnel and the plant itself. (authors)

[en] In this paper it is presented an experimental test for non-radioactive antimony removal from aqueous solutions using magnetite (Fe3O4) powder. Antimony (Sb) solubility in water was tested in autoclave using primary heat transport conditions. Solution obtained from autoclave was sent to Inductively Coupled Plasma Optic Emission Spectrometry (ICPOES) for quantitative analysis of Sb and a part of it was used for the adsorption tests. Furthermore, it was studied how pH influences antimony adsorption onto magnetite surface. After adsorption, solutions were filtered on Cellulose Mixed Ester membrane to remove magnetite powder and then the aqueous solutions were sent to ICP-OES to determine the Sb concentration. Forwards, magnetite powder from the filters were examined by optical microscopy. The experimental tests have shown that antimony adsorption on magnetite is decreasing at high pH of solution. (authors)