Critical soft landing technology issues for future US space missions

A programmatic need for research and development to support parachute-based landing systems has not existed since the end of the Apollo missions in the mid-1970s. Now, a number of planned space programs require advanced landing capabilities for which the experience and technology base does not currently exist. New requirements for landing on land with controllable, gliding decelerators and for more effective impact attenuation devices justify a renewal of the landing technology development effort that existed during the Mercury, Gemini, and Apollo programs. A study was performed to evaluate the current and projected national capability in landing systems and to identify critical deficiencies in the technology base required to support the Assured Crew Return Vehicle and the Two-Way Manned Transportation System. A technology development program covering eight landing system performance issues is recommended

Technical Support for Soviet C3/CM WARGAMING at the Naval Postgraduate School

The work described herein was conducted by ROLANDS & ASSOCIATES Corporation for the Naval Postgraduate School, Monterey, California, under Purchase Order Number N62271-89-M-0519, dated 12/06/88. The NPS Basic Research Group comprised Professors J. Sternberg, C. R. Jones, and R. Thackery. Lois Brunner provides technical support to the Group. This work was performed in support of the BRG evaluation of options for simulation (wargaming) support for their research

Rod ejection simulation on VVER 1000/320 core using PARCS/TRACE

The rod ejection (RE) is a design basis accident in accordance with NUREG-0800 and usually studied using point kinetics. In this thesis a 3D kinetic model is prepared and coupled with a thermal hydraulic system code for simulating this accident scenario for general VVER 1000 technology. This topic has been defined by the Research Centre Rez of the Czech Republic as a part of a larger project concerning beyond design basis accident focused on the Station Black Out (SBO) and a Loss of Ultimate Heat Sink (LOUHS). Because of this, the simulation conditions will considered under SBO scenario. Initially the state of the art is discussed, followed by the general information on the major documentation needed for the analysis (10-CFR, NUREG-0800). This thesis shows the complete coupling methodology from a cross section generation to transient coupled calculation

GEN-IV LFR development: Status & perspectives

Since Lead-cooled Fast Reactors (LFR) have been conceptualized in the frame of Generation IV International Forum (GIF), great interest has focused on the development and testing of new technologies related to Heavy Liquid Metal (HLM) nuclear reactors. In this frame, ENEA developed one of the larger European experimental fleet of experimental facilities aiming at investigating HLM thermal-hydraulics, coolant chemistry control, corrosion behavior for structural materials, and at developing components, instrumentations and innovative systems, supported by experiments and numerical tools. The present work aims at highlighting the capabilities and competencies developed by ENEA so far in the frame of the liquid metal technologies for GEN-IV LFR. In particular, an overview on the ongoing R&D experimental program will be depicted considering the actual fleet of facilities: CIRCE, NACIE-UP, LIFUS5, LECOR and HELENA. CIRCE (CIRColazione Eutettico) is the largest HLM pool facility presently in operation worldwide. Full scale component tests, thermal stratification studies, operational and accidental transients and integral tests for the nuclear safety and SGTR (Steam Generator Tube Rupture) events in a large pool system can be studied. NACIE-UP (NAtural CIrculation Experiment-UPgraded) is a loop with a HLM primary and pressurized water secondary side and a 250 kW power Fuel Pin Simulator working in natural and mixed convection. LIFUS5 (lithium for fusion) is a separated effect facility devoted to the HLM/Water interaction. HELENA (HEavy Liquid metal Experimental loop for advanced Nuclear applications) is a pure lead loop with a mechanical pump for high flow rates experiments. LECOR (LEad CORrosion) is a corrosion loop facility with oxygen control system installed. All the experiment actually ongoing on these facilities are described in the paper, depicting their role in the context of GEN-IV LFR development

Differentiator factors in the implementation of social network sites

Estágio realizado na Business Analyst da Documento Crítico - Desenvolvimento de Software, S. A. (Cardmobili) e orientado pelo Eng.ª Catarina MaiaTese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 200

Approaching Dynamic PSA within CANDU 6 NPP

The outline of this dissertation is going to present the applications that are the subject of the work and also the lay down of work content. Chapter 1 reviews the conventional PSA main concepts, summarizes a short introduction history of Dynamic PSA (DPSA) and presents a non-exhaustive DPSA state-of-the-art with the recent and future developments. Chapter 2 presents the first application of the thesis, which is actually an introduction in the context of the Integrated Dynamic Decision Analysis (IDDA) code, that represents the main tool used in the attempt of approaching the Dynamic PSA. Starting from a description that reflects the level of knowledge about the system, IDDA code is able to develop all the scenarios of events compatible with the description received, from both points of view: either logical construction, or probabilistic coherence. By describing the system configuration and operation in a logically consistent manner, all the information is worked out by the code and is made available to the analyst as results in terms of system unavailability, minimal cut sets, uncertainty associated. The code allows also the association of different consequences that could be of interest for the analyst. The consequences could be of any type, such as economical, equipment outage time, etc.; for instance it can be considered an outage time for certain components of the system and then is calculated the “expected risk”. The association of consequences provides the inputs for a good decision making process. Chapter 3 represents the core applications of the present work. The applications purpose is the coupling between the logic probabilistics of the system or plant and associated phenomenology of primary heat transport system of a generic CANDU 6 NPP. First application is the coupling between the logic-probabilistic model of EWS system and associated phenomenology of primary heat transport system of CANDU 6 NPP. The considered plant transient is the total Loss of Main Feed-water with or without the coincident failure of the Emergency Water Supply System. The second application is considering the CANDU 6 Station Blackout as plant transient-consequential condition, moreover the loss of all AC power sources existing on the site. The transient scenarios development consider the possibility to recover the offsite grid and the use of mobile diesel generators in order to mitigate the accident consequences. The purpose is to challenge the plant design and response and to check if the plant conditions of a severe accident are reached. The plant response is challenged for short and long periods of time. The IDDA code allows interfacing the logic-probabilistic model of the system with the plant response in time, therefore with the evolution in time of the plant process variables. This allows raising sequences of possible events related in cause-consequence reasoning, each one giving place to a scenario with its development and its consequences. Therefore this allows acquiring the knowledge not only of which sequences of events are taking place, but also of the real environment in which they are taking place. Associating the system sequences that lead to system unavailability on demand with the resulting phenomenology proves to be a useful tool for the decision making process, both in the design phase and for the entire power plant life time. Chapter 4 presents future possible applications that could be developed with the present Dynamic PSA approach. A particular application could be the optimization or development of robust plant emergency operating procedures. In fact it consists in the coupling between the logic-probabilistics of the plant configurations corresponding to the Emergency Operating Procedure (EOP) and the associated phenomenology of the primary heat transport systems with the consideration for the plant safety systems. The application could highlight those situations where the plant fails either because of hardware failures or system dynamics and furthermore to reveal those situations where changing of the hardware states brings the process variables of the system state out of the system domain. A timeline course should be created for the process variables characterizing the plant state and that should reveal the time windows that operators have at disposition for intervention, in order to avoid potentially catastrophic conditions. Some week points in the EOP could be identified and then resolutions to be provided for their improvement, on the basis of sensitivity analyses. Chapter 5 presents the conclusions and the insights of the work and outlines possible improvements in terms of the present methodology proposed

A Bayesian Network Approach to Estimating Software Reliability of RSG-GAS Reactor Protection System

Reliability represents one of the most important attributes of software quality. Assessing the reliability of software embedded in the safety of highlycritical systems is essential. Unfortunately, there are many factors influencing software reliability that cannot be measured directly. Furthermore, the existing models and approaches for assessing software reliability have assumptions and limitations which are not directly acceptable for all systems, such as reactor protection systems. This paper presents the result of a study which aims to conduct quantitative assessment of the software reliability at the reactor protection system (RPS) of RSG-GAS based on software development life cycle. A Bayesian network (BN) is applied in this research and used to predict the software defect in the operation which represents the software reliability. The availability of operation failure data, characteristics of the RPS components and their operation features, prior knowledge on the software development and system reliability, as well as relevant finding from references were considered in the assessment and the construction of nodes on causal network model. The structure of causal model consists of eight nodes including design quality, problem complexity, and defect inserted in the software. The calculation result using Agenarisk software revealed that software defect in the operation of RPS follows binomial statistic distribution with the mean of 1.393. This number indicated the high software maturity level and high capability of the organization. The improvement of software defect concentration range on the posterior distribution compared with the prior’s is also identified. The result achieved is valuable for furtherreliability estimation by introducingnew evidence and experience data, and by setting up an appropriate plan in order to enhance software reliability in the RPS