Reliability and fault tolerance in the European ADS project

After an introduction to the theory of reliability, this paper focuses on a description of the linear proton accelerator proposed for the European ADS demonstration project. Design issues are discussed and examples of cases of fault tolerance are given.Comment: 14 pages, contribution to the CAS - CERN Accelerator School: Course on High Power Hadron Machines; 24 May - 2 Jun 2011, Bilbao, Spai

Cyclodipeptide synthases, a family of class-I aminoacyl-tRNA synthetase-like enzymes involved in non-ribosomal peptide synthesis

Cyclodipeptide synthases (CDPSs) belong to a newly defined family of enzymes that use aminoacyl-tRNAs (aa-tRNAs) as substrates to synthesize the two peptide bonds of various cyclodipeptides, which are the precursors of many natural products with noteworthy biological activities. Here, we describe the crystal structure of AlbC, a CDPS from Streptomyces noursei. The AlbC structure consists of a monomer containing a Rossmann-fold domain. Strikingly, it is highly similar to the catalytic domain of class-I aminoacyl-tRNA synthetases (aaRSs), especially class-Ic TyrRSs and TrpRSs. AlbC contains a deep pocket, highly conserved among CDPSs. Site-directed mutagenesis studies indicate that this pocket accommodates the aminoacyl moiety of the aa-tRNA substrate in a way similar to that used by TyrRSs to recognize their tyrosine substrates. These studies also suggest that the tRNA moiety of the aa-tRNA interacts with AlbC via at least one patch of basic residues, which is conserved among CDPSs but not present in class-Ic aaRSs. AlbC catalyses its two-substrate reaction via a ping-pong mechanism with a covalent intermediate in which l-Phe is shown to be transferred from Phe-tRNAPhe to an active serine. These findings provide insight into the molecular bases of the interactions between CDPSs and their aa-tRNAs substrates, and the catalytic mechanism used by CDPSs to achieve the non-ribosomal synthesis of cyclodipeptides

ETUDE DE CAVITES SUPRACONDUCTRICES POUR LES ACCELERATEURS DE PROTONS DE FORTE PUISSANCE

ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Dynamic compensation of an rf cavity failure in a superconducting linac

An accelerator driven system (ADS) for transmutation of nuclear waste typically requires a 600 MeV–1 GeV accelerator delivering a proton flux of a few mA for demonstrators, and of a few tens of mA for large industrial systems. Such a machine belongs to the category of the high-power proton accelerators, with an additional requirement for exceptional “reliability”: because of the induced thermal stress to the subcritical core, the number of unwanted “beam trips” should not exceed a few per year, a specification that is several orders of magnitude above usual performance. In order to meet this extremely high reliability, the accelerator needs to implement, to the maximum possible extent, a fault-tolerance strategy that would allow beam operation in the presence of most of the envisaged faults that could occur in its beam line components, and in particular rf systems’ failures. This document describes the results of the simulations performed for the analysis of the fault-tolerance capability of the XT-ADS superconducting linac in the case of an rf cavity failure. A new simulation tool, mixing transient rf behavior of the accelerating cavities with full 6D description of the beam dynamics, has been developed for this purpose. Fast fault-recovery scenarios are proposed, and required research and development is identified

Investigation of different layouts for the EURISOL driver

This technical note describes, first, the main parameters of the driver optimised for the protons and, in a second part, shows optimised layouts which include the additional features

The Myrrha linear accelerator

Ac­cel­er­a­tor Driv­en Sys­tems (ADS) are promis­ing tools for the ef­fi­cient trans­mu­ta­tion of nu­cle­ar waste prod­ucts in ded­i­cat­ed in­dus­tri­al in­stal­la­tions, called trans­muters. The Myrrha pro­ject at Mol, Bel­gium, placed it­self on the path to­wards these ap­pli­ca­tions with a mul­ti­pur­pose and ver­sa­tile sys­tem based on a liq­uid PbBi (LBE) cooled fast re­ac­tor (80 MWth) which may be op­er­at­ed in both crit­i­cal and sub­crit­i­cal modes. In the lat­ter case the core is fed by spal­la­tion neu­trons ob­tained from a 600 MeV pro­ton beam hit­ting the LBE coolant/tar­get. The ac­cel­er­a­tor pro­vid­ing this beam is a high in­ten­si­ty CW su­per­con­duct­ing linac which is laid out for the high­est achiev­able re­li­a­bil­i­ty. The com­bi­na­tion of a par­al­lel re­dun­dant and of a fault tol­er­ant scheme should allow ob­tain­ing an MTBF value in ex­cess of 250 hours that is re­quired for op­ti­mal in­tegri­ty and suc­cess­ful op­er­a­tion of the ADS. Myrrha is ex­pect­ed to be op­er­a­tional in 2023. The forth­com­ing 4-year pe­ri­od is fully ded­i­cat­ed to R&D ac­tiv­i­ties, and in the field of the ac­cel­er­a­tor they are strong­ly fo­cused on the re­li­a­bil­i­ty as­pects and on the prop­er shap­ing of the beam trip spec­trum

Control System Developments for the MYRRHA Linac

International audienceThe goal of the MYRRHA project is to demonstrate the technical feasibility of transmutation in a 100 MWth Accelerator Driven System by building a new flexible irradiation complex in Mol (Belgium). The MYRRHA facility requires a 600 MeV linear accelerator delivering a maximum proton flux of 4 mA in continuous operation, with an additional requirement for exceptional reliability. The control system of the future MYRRHA linac will have an essential role to play in this extreme reliability scenario. On the one hand the intrinsic reliability of the entire control system must be ensured. On the other hand control system will have to take up very high level duties of complex decision taking. This paper summarizes the ongoing developments for the concept design of such a control system. The related experimental activities performed and planned around the MYRRHA injector platform (ECR ion source + LEBT + RFQ) will also be described