Review of the risk assessment of buoyancy loss (RABL) project
This report presents a review of the Norwegian 'Risk Assessment of Buoyancy Loss' (RABL) project, completed in 1988. RABL was undertaken in the aftermath of the Alexander L. Kielland and Ocean Ranger accidents. RABL's stated purpose was to investigate causes of loss of buoyancy of semisubmersible drilling platforms, with the overall objective of developing an analytical procedure for consideration of buoyancy loss. This procedure was intended to be analogous to guidelines applied to fixed platforms in Norwegian waters. RABL demonstrated that it is practical to carry out a risk assessment of buoyancy loss for semisubmersibles. The RABL methodology and procedure were considered to be robust and sensitive to differences between concepts, and RABL recommended that the new analysis methodology should be used to assess safety levels for new platform designs, or for existing platforms subject to changes in operational premises. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy. ISBN 0 7176 2729 2 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the copyright owner. iv v EXECUTIVE SUMMARY This report presents a review of the Norwegian 'Risk Assessment of Buoyancy Loss' (RABL) project, completed in 1988. RABL was undertaken in the aftermath of the Alexander L. Kielland and Ocean Ranger accidents. RABL's stated purpose was to investigate causes of loss of buoyancy of semi-submersible drilling platforms, with the overall objective of developing an analytical procedure for consideration of buoyancy loss. This procedure was intended to be analogous to guidelines applied to fixed platforms in Norwegian waters. RABL demonstrated that it is practical to carry out a risk assessment of buoyancy loss for semi-submersibles. The RABL methodology and procedure were considered to be robust and sensitive to differences between concepts, and RABL recommended that the new analysis methodology should be used to assess safety levels for new platform designs, or for existing platforms subject to changes in operational premises. RABL found that the main hazards were ship collisions, ballast system failures and blowouts. Technical recommendations were made on each of these aspects. RABL concluded that upper-deck reserve buoyancy (as required by NMD) provides …
Marine and Hydrokinetic Technology Development Risk Management Framework
Over the past decade, the global marine and hydrokinetic (MHK) industry has suffered a number of serious technological and commercial setbacks. To help reduce the risks of industry failures and advance the development of new technologies, the U.S. Department of Energy (DOE) and the National Renewable Energy Laboratory (NREL) developed an MHK Risk Management Framework. By addressing uncertainties, the MHK Risk Management Framework increases the likelihood of successful development of an MHK technology. It covers projects of any technical readiness level (TRL) or technical performance level (TPL) and all risk types (e.g. technological risk, regulatory risk, commercial risk) over the development cycle. This framework is intended for the development and deployment of a single MHK technology—not for multiple device deployments within a plant. This risk framework is intended to meet DOE’s risk management expectations for the MHK technology research and development efforts of the Water Power Program (see Appendix A). It also provides an overview of other relevant risk management tools and documentation.1 This framework emphasizes design and risk reviews as formal gates to ensure risks are managed throughout the technology development cycle. Section 1 presents the recommended technology development cycle, Sections 2 and 3 present tools to assess themore » TRL and TPL of the project, respectively. Section 4 presents a risk management process with design and risk reviews for actively managing risk within the project, and Section 5 presents a detailed description of a risk registry to collect the risk management information into one living document. Section 6 presents recommendations for collecting and using lessons learned throughout the development process.« less
Parametric Study of Vortices Shed from Airfoil Vortex Generators
Extensive parametric study of vortices shed from the tips of airfoil vortex generators has been conducted to determine the dependence of initial vortex circulation and peak vorticity on elements of airfoil geometry and impinging-flow conditions. The vortex generators were symmetric airfoils examined in subsonic airflow on the surface of a straight pipe. The circulation and peak-vorticity data were derived from cross-plane velocity measurements acquired with a seven-hole probe one chord length downstream of the airfoil-trailing-edge-tip location. Circulation and peak vorticity are observed to be proportional to the freestream Mach number, the angle of attack, and the span-to-boundary-layer-thickness ratio