1,721,195 research outputs found
Reliability estimation for double containment piping
No full textDouble walled or double containment piping is considered for use in the ITER international project and other next-generation fusion device designs to provide an extra barrier for tritium gas and other radioactive materials. The extra barrier improves confinement of these materials and enhances safety of the facility. This paper describes some of the design challenges in designing double containment piping systems. There is also a brief review of a few operating experiences of double walled piping used with hazardous chemicals in different industries. The authors recommend approaches for the reliability analyst to use to quantify leakage from a double containment piping system in conceptual and more advanced designs. The paper also cites quantitative data that can be used to support such reliability analyses
Tritium management and safety issues in ITER and DEMO breeding blankets
No full textSafe, reliable and efficient tritium management in the breeder blanket faces unique technological challenges. Beside the tritium recovery efficiency in the tritium extraction and coolant purification systems, the tritium tracking accuracy between the inner and outer fuel cycle shall also be demonstrated. Furthermore, it is self-evident that safe handling and confinement of tritium need to be stringently assured to evolve fusion as a reliable technique. The present paper gives an overview of tritium management in breeder blankets. After a short introduction into the tritium fuel cycle and blanket basics, open tritium issues are discussed, thereby focusing on tritium extraction from blanket, coolant detritiation and tritium analytics and accountancy, necessary for accurate and reliable processing as well as for book-keeping. © 2013 Elsevier B.V. All rights reserved
Summary of the 1st International Workshop on Environmental, Safety and Economic Aspects of Fusion Power
No full textThe 1st International workshop on Environmental, Safety and Economic Aspects of Fusion Power (ESEFP) was held on 13 September 2015 at Jeju Island, South Korea. The workshop was initiated by the International Energy Agency Implementing Agreement on a Co-operative Program on ESEFP. The workshop was well attended with about forty participants representing twelve institutions in ten countries. The presentations covered safety issues and environmental impacts, availability improvement and risk control and socio-economic aspects of fusion power. Safety and licensing gaps between DEMO and ITER were discussed in depth with the consensus output presented as a plenary presentation at the 12th International Symposium on Fusion Nuclear Technology (ISFNT-12). The next workshop is planned to be held in conjunction with the ISFNT-13 in 2017. © 2016 IAEA, Vienna
RAMI analyses for the primary heat transfer systems of breeding blankets and the related balance of plant of DEMO reactor
No full textTwo models are currently taken as reference for the breeding blanket (BB) of DEMO, the Helium Cooled Pebble Bed (HCPB) and the Water Cooled Lithium Lead (WCLL). For both the models two Balance of Plant (BOP) configurations are currently investigated. They are all based on four independent primary heat transfer systems (PHTSs). The largest PHTS is devoted to remove the BB thermal power, two PHTSs for the divertor (DIV) and one for the vacuum vessel (VV) heat removals. Both DIV loops and VV loop transfer their thermal power directly to the power conversion system (PCS). The two BOP configurations are investigated to cope with the pulsed operation of the reactor. The first configuration consists of an “indirect coupling” of the BB PHTS to the PCS by an Intermediate Heat Transfer System placed in between them. The second configuration consists in a “direct-coupling” of the BB PHTS to the PCS. Reliability, availability, maintainability and inspectability (RAMI) analyses for the four PHTS and PCS configurations are presented in this paper. The Failure Mode, Effect Analysis (FMEA) and the Reliability Block Diagram (RBD) methodologies have been used to perform the studies. As main result can be highlighted that even the low reliability of the systems to operate without failure and the large number of requests of corrective maintenance, all the systems are in compliance with an operational availability target of 30 %
Design and R&D activities of TriPla-CA Consortium in support of ITER Tritium Plant development
No full textThe design of ITER tritium processing systems should benefit from experimental data and process validation on experimental facilities that are ITER relevant. TriPla-CA, which is a consortium of four EU laboratories aiming to support tritium relevant activities for ITER design is carrying out R&D and design for ITER Tritium Plant. Several rigs and experimental facilities have been enhanced and developed in order to explore a wide range of envisaged scenarios of some ITER Tritium Plant systems such as water detritiation system (WDS), isotope separation system and highly tritiated water processing. Beside the experimental activities, the enhancement of the relevant software for simulation and design of various tritium processing systems is ongoing. The main achievements concerning the R&D, the mechanical design including the seismic calculations of some ITER WDS components and the main expertize and the hardware available inside the consortium are presented. © 2014 Elsevier B.V
Reliability and availability requirements analysis for DEMO: Fuel Cycle system
No full textTwo of the key elements of the engineering development of the DEMO reactor are the definitions of reliability and availability requirements (or targets). The availability target for a hypothesized Fuel Cycle has been analysed as a test case. The analysis has been done on the basis of the experience gained in operating existing tokamak fusion reactors and developing the ITER design. Plant Breakdown Structure (PBS) and Functional Breakdown Structure (FBS) related to the DEMO Fuel Cycle and correlations between PBS and FBS have been identified. At first, a set of availability targets has been allocated to the various systems on the basis of their operating, protection and safety functions. 75% and 85% of availability has been allocated to the operating functions of fuelling system and tritium plant respectively. 99% of availability has been allocated to the overall systems in executing their safety functions. The chances of the systems to achieve the allocated targets have then been investigated through a Failure Mode and Effect Analysis and Reliability Block Diagram analysis. The following results have been obtained: i) the target of 75% for the operations of the fuelling system looks reasonable, while the target of 85% for the operations of the whole tritium plant should be reduced to 80%, even though all the tritium plant systems can individually reach quite high availability targets, over 90%-95%; ii) all the DEMO Fuel Cycle systems can reach the target of 99% in accomplishing their safety functions. © 2015, American Nuclear Society. All rights reserved
Preliminary safety studies for the DEMO HCPB blanket concept
No full textHelium Cooled Pebble Bed (HCPB) blanket concept is one of the DEMO (Demonstration Power Plant) blanket concepts running for the final design selection. Concept relevant safety needs to be addressed at the early stage of the design. In this paper the preliminary safety studies for the current concept have been performed with respect to the FFMEA (Functional Failure Mode and Effect Analysis), the confinement strategy, identification of source terms, and selection of critical event sequences. © 2015 Elsevier B.V. All rights reserved
RAMI assessment for IFMIF lithium facility
No full textA RAMI (reliability, availability, maintainability and inspectability) assessment performed on the IFMIF (International Fusion Materials Irradiation Facility) Lithium Facility (LF) is presented. Given the high availability requirements for the IFMIF plant, a target requirement of 94% availability has been attributed to the LF and its feasibility verified for the proposed system design. The LF performance for the foreseen operation mission has been investigated by the mean of failure mode, effect and criticality analysis (FMECA) and reliability block diagrams (RBDs). The first assessment performed on the base of the present design did not satisfy the above target requirement. Then, possible optimizations in design solutions and maintenance policy have been investigated. The RBD analysis shows that with some improvements the LF could be able to comply with the availability target requested, as the obtained mean availability for 10 years of simulation is of 93.4% and the inherent availability more than 99%. The reliability to operate the LF without failure during the yearly scheduled operation time is about 64%. Most critical components in terms of impact on LF reliability and availability, are: (i) the Li loop Target Section (back plate) and electro-magnetic pumps for the main loop, (ii) the getter beds of the hydrogen hot trap and the electromagnetic pump for the impurity control system. © 2015 Elsevier B.V. All rights reserved
RAMI analysis for DEMO HCPB blanket concept cooling system
No full textA preliminary RAMI (reliability, availability, maintainability and inspectability) assessment for the HCPB (helium cooled pebble bed) blanket cooling system based on currently available design for DEMO fusion power plant is presented. The following sub-systems were considered in the analysis: blanket modules, primary cooling loop including pipework and steam generators lines, pressure control system (PCS), coolant purification system (CPS) and secondary cooling system. For PCS and CPS systems an extrapolation from ITER Test Blanket Module corresponding systems was used as reference design in the analysis. Helium cooled pebble bed (HCPB) system reliability block diagrams (RBD) models were implemented taking into account: system reliability-wise configuration, operating schedule currently foreseen for DEMO, maintenance schedule and plant evolution schedule as well as failure and corrective maintenance models. A simulation of plant activity was then performed on implemented RBDs to estimate plant availability performance on a mission time of 30 calendar years. The resulting availability performance was finally compared to availability goals previously proposed for DEMO plant by a panel of experts. The study suggests that inherent availability goals proposed for DEMO PHTS system and Tokamak auxiliaries are potentially achievable for the primary loop of the HCPB concept cooling system, but not for the secondary loop. A sensitivity analysis is also presented to explore results dependency on key estimated parameters and analysis assumptions. © 2015 Elsevier B.V. All rights reserved
Approach in improving reliability of DEMO
No full textReliability, Availability, Maintainability and Inspectability (RAMI) are key elements in the engineering development of the Demonstration Power Plant (DEMO) reactor. RAMI assessments play an important role during all design cycle phases by focusing on different aspects depending on the development stage. In fact, system functions, related requirements and deriving constraints are the main objective of RAMI assessment during pre-conceptual and conceptual design phases, when getting insight on the rationale of the plant. The identification of potential failure mechanisms, needs of design updates to remove such mechanisms or mitigate related consequences, become the main goal of analysis as design details increase during subsequent plant development phases. Some of the RAMI analyses performed in the 2019 for different DEMO systems and breeding blanket configurations are here presented. Results in terms of expected annual frequency of failures of components, of specific failure events and reliability/availability parameters are reported together with indications about criticality and suggestions for designers to improve reliability and availability of the systems and of the reactor. The study is based on Failure Mode and Effect Analysis (FMEA) and Reliability Block Diagram (RBD) analysis methodologies
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