Detailed neutronic study of the power evolution for the European Sodium Fast Reactor during a positive insertion of reactivity

Abstract The new reactor concepts proposed in the Generation IV International Forum require the development and validation of new components and new materials. Inside the Collaborative Project on the European Sodium Fast Reactor, several accidental scenario have been studied. Nevertheless, none of them coped with mechanical safety assessment of the fuel cladding under accidental conditions. Among the accidental conditions considered, there is the unprotected transient of overpower (UTOP), due to the insertion, at the end of the first fuel cycle, of a positive reactivity into the reactor core as a consequence of the unexpected runaway of one control rod. The goal of the study was the search for a detailed distribution of the fission power, in the radial and axial directions, within the power peaked fuel pin under the above accidental conditions. Results show that after the control rod ejection an increase from 658 W/cm 3 to 894 W/cm 3 , i.e. of some 36%, is expected for the power peaked fuel pin. This information will represent the base to investigate, in a future work, the fuel cladding safety margin

Identification and categorisation of safety issues for ESNII reactor concepts. Part I: Common phenomena related to materials

International audience; With the aim to develop a joint proposal for a harmonised European methodology for safety assessment of advanced reactors with fast neutron spectrum, SARGEN-IV (Safety Assessment for Reactors of Gen IV) Euratom coordination action project gathered together twenty-two partners' safety experts from twelve EU Member States. The group consisted of eight European Technical Safety Organisations involved in the European Technical Safety Organisation Network (ETSON), European Commission's Joint Research Centre (JRC), system designers, industrial vendors as well as research and development (RandD) organisations. To support the methodology development, key safety features of four fast neutron spectrum reactor concepts considered in Deployment Strategy of the Sustainable Nuclear Energy Technology Platform (SNETP) were reviewed. In particular, outcomes from running European Sustainable Nuclear Industrial Initiative (ESNII) system projects and related Euratom collaborative projects for Sodium-cooled Fast Reactors, Lead-cooled Fast Reactors, Gas-cooled Fast Reactors, and the lead-bismuth eutectic cooled Fast Spectrum Transmutation Experimental Facility were gathered and critically assessed. To allow a consistent build-up of safety architecture for the ESNII reactor concepts, the safety issues were further categorised to identify common phenomena related to materials. Outcomes of the present work also provided guidance for the identification and prioritisation of further RandD needs respective to the identified safety issues. © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-NDlicense

Space weathering simulations through controlled growth of iron nanoparticles on olivine

Airless planetary bodies are directly exposed to space weathering. The main spectral effects of space weathering are darkening, reduction in intensity of silicate mineral absorption bands, and an increase in the spectral slope towards longer wavelengths (reddening). Production of nanophase metallic iron (npFe0) during space weathering plays major role in these spectral changes. A laboratory procedure for the controlled production of npFe0 in silicate mineral powders has been developed. The method is based on a two-step thermal treatment of low-iron olivine, first in ambient air and then in hydrogen atmosphere. Through this process, a series of olivine powder samples was prepared with varying amounts of npFe0 in the 7-20 nm size range. A logarithmic trend is observed between amount of npFe0 and darkening, reduction of 1 µm olivine absorption band, reddening, and 1 µm band width. Olivine with a population of physically larger npFe0 particles follows spectral trends similar to other samples, except for the reddening trend. This is interpreted as the larger, ~40-50 nm sized, npFe0 particles do not contribute to the spectral slope change as efficiently as the smaller npFe0 fraction. A linear trend is observed between the amount of npFe0 and 1 µm band center position, most likely caused by Fe2+ disassociation from olivine structure into npFe0 particles.Peer reviewe

Status of Generation-IV Lead Fast Reactor Activities

Since 2012 the Lead-cooled Fast Reactor provisional System Steering Committee (LFR-pSSC) of the Generation IV International Forum (GIF) has developed a number of top level strategic activities with the aim to assist and support development of Lead-cooled Fast Reactor technology in member countries and entities. The current full members of the GIF-LFR-pSSC (i.e., signatories of the GIF LFR Memorandum of Understanding /MoU/) are: EURATOM, JAPAN, the RUSSIAN FEDERATION, and the REPUBLIC OF KOREA. The pSSC also benefits from the active participation of its observers: the UNITED STATES and the PEOPLE’S REPUBLIC OF CHINA. The paper highlights some of the main collaborative achievements of LFR-pSSC, including the development of the LFR System Research Plan, the LFR White Paper on Safety, the LFR System Safety Assessment paper as well as the LFR Safety Design Criteria paper. The paper then presents the status of the development of LFRs in the GIF member countries and entities. The collaboration among partners of the GIF-LFR-pSSC has proven its effectiveness in assisting the development of LFRs through an open, interactive and collegial environment, developing important synergies and exchange of both technical and strategic information

Depletion analysis of the HELIOS experiment using the MCB code

The focus of our studies is to present an advanced depletion analysis of the HELIOS experiment by means of the Monte Carlo continuous energy burn-up code (MCB). The MCB was used mainly to calculate nuclide density evolution in nuclear reactor cores. We present the capability of the MCB to investigate the depletion of nuclear fuel samples irradiated in the HELIOS experiment. In our studies we traced the behaviour of the main fissile isotopes, 242mAm and 239Pu, respectively. We also perform a sensitivity analysis to the choice of JEF2.2 and JEFF3.1 cross section libraries in terms of the released fission power and the evolution of actinide inventories. The amount of He produced at the end of irradiation, as well as Am and Pu depletion, were also considered

Safety analysis results of the DBC transients performed for the ALFRED reactor

The LEADER project aims at the development to a conceptual level of a Lead Fast Reactor Industrial size plant and at a scaled demonstrator of the LFR technology - ALFRED. This paper presents the main safety transient analysis results using the system codes RELAP5, TRACE-FRED, SIM-LFR, CATHARE and SIMMER of the DBC (Design Basis Condition) transients for the ALFRED reactor. Apart from the traditional set of protected transients (PLOF, PTOP, LOOP), safety analysis was carried out for a number of carefully selected plant specific DBC transients, thus enveloping a wide spectrum of design basis conditions

SARGEN-IV Consideration on the possible content of the safety analysis report for innovative ESNII reactors

International audienceIn view of the potential deployment of demonstrators and prototypes associated with the European Sustainable Nuclear Industrial Initiative (ESNII), the present licensing framework, based on the current Light Water Reactor (LWR) technology, will have to adjust as necessary taking into account to the new safety aspects introduced by these innovative technologies. Within the SARGEN-IV project under the Euratom Framework Programme FP7, an extensive work has been done to review the critical safety features of the reactor concepts developed under ESNII. This review has also been used as a reference to provide guidelines on the structure and content of the Safety Analysis Report (SAR) for the innovative ESNII reactors. Structure and content of a SAR generally differ among countries. The approach followed to give recommendations and guidance was to adopt as far as possible the format of the current practices for LWR based on the US NRC Reg Guide 1.70 together with IAEA publication GS-G-4.1 and to identify those chapters whose subjects need to be adapted to the specific design. Due to the innovative nature of the design, the licensing process for new ESNII concepts may take longer. The early involvement of regulators in defining safety objectives and criteria and acceptable solutions to meet these criteria may be beneficial to shorten this process. Therefore, it is recommended that parts of the SAR should be submitted to the regulatory body at an early stage and in accordance with an agreed timetable; this approach will permit a smoother review process and help preventing unnecessary delays. © 2016 The Authors. Published by Elsevier B.V