Containment Barriers Research Articles

Safety Analysis of a Loss-Of-Coolant Accident in a Breeding Blanket for Experimental Fusion Reactors

A LOCA in a blanket design proposed for NET (Next European Torus) is investigated. The structural analysis of a damaged breeder unit shows that this first containment barrier has a high probability of survival to this accident. The radioactive sources involved are evaluated and an assessment is made of all containment barriers and associated protection systems.

Bentonite slurry trenches

Soil-bentonite slurry trench cutoff walls have been extensively used as engineered barriers for contaminant containment. In some regions without appropriate sodium bentonite (NaB), local calcium bentonite (CaB) that is cheap and abundantly available may be considered as an alternative material. However, CaB has a poor swelling capacity and it is important to improve the properties to meet the requirements of the cutoff walls. As a highly effective filtrate reducer and viscosifier, polyanionic cellulose (PAC) has been used to modify NaB and Na activated CaB to enhance their chemical compatibilities, but its application to natural CaB has been seldom studied. Therefore, this study aimed to identify the optimal reaction condition for PAC-CaB preparation using a more systematic slurrying-drying-grinding method and preliminarily evaluate the application potential of PAC-CaB in slurry trench cutoff walls from the perspective of the workability of bentonite slurry. The effect of PAC modification on the physicochemical properties of CaB and workability of CaB slurry were explored by a series of laboratory experiments. The modification mechanisms of PAC were comprehensively revealed by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results show that as the PAC dosage (by mass) increased from 2 to 8%, the swell index of CaB increased almost linearly and exceeded that of NaB. Both 4% and 8%PAC-CaBs had a lower hydraulic conductivity and a better chemical compatibility (using 10 mM CaCl2) than NaB. Moreover, PAC modification could significantly enhance the workability of CaB slurry, approaching or even exceeding that of NaB slurry, and reduce the bentonite content. A planar or spatial network microstructure was observed in PAC-CaB due to the interactions between PAC and CaB involving bridging and bonding. Overall, PAC is a promising modifier for CaB and PAC-CaB has the potential to replace the NaB in stabilizing the trench wall during construction.

Airborne fiber control in buildings during asbestos material removal by amended water methodology

Removal of friable asbestos-containing material can cause high levels of airborne contamination. The potential efficacy of control methods recommended by the Environmental Protection Agency (EPA) was evaluated by examination of 503 air samples obtained in 40 removal projects in a number of locations. The EPA methodology with amended water for fiber emission control was utilized on all of the observed removal projects. The projects were also considered to be well controlled and the study cannot be considered representative of common work practices. The EPA amended water methodology, when effectively utilized and administered, can provide a high degree of contamination control. Mean fiber levels in the work area in this study (1.1 f/cm 3) were well below those of dry removal (38.9 f/cm 3) and control by application by untreated water (28.6 f/cm 3). Airborne contamination was higher during bagging debris (3.8 f/cm 3) than during material removal from structural surfaces. The range of fiber levels during removal was 0.0 to 37.0 f/cm 3 and fibers were detected from initial barrier construction through final cleaning. Contamination was also occasionally detected outside work area containment barriers. Air sampling produced 0.0 counts in areas of obvious contamination by settled dust and debris. Control methodologies, respiratory protection, and decontamination are discussed.

Hydraulic Fracture Propagation in Layered Rock: Experimental Studies of Fracture Containment

Abstract Fracture geometry is an important concern in the design of a massive hydraulic fracture for improved natural gas recovery from low-permeability reservoirs. Determination of the extent of vertical fracture growth and containment in layered rock, a priori, requires an improved understanding of the parameters that may control fracture growth across layer interfaces. We have conducted laboratory hydraulic fracture experiments and elastic finite element studies that show that at least two distinct geologic conditions can inhibit or contain the vertical growth of hydraulic fractures in layered rock: (1) a weak interfacial shear strength of the layers and (2) an increase in the minimum horizontal compressive stress in the bounding layer. The second condition is more important and more likely to occur at depth. Differences in elastic properties within a layered rock mass may be important—not as a containment barrier per se, but in the manner in which variations in elastic properties affect the vertical distribution of the minimum horizontal stress magnitude. These results suggest that improved fracture treatment designs and an assessment of the potential success of stimulations in low-permeability reservoirs can be made by determining the in-situ stress state in the producing interval and bounding formations before stimulation. If the bounding formations have a higher minimum horizontal stress, then one can optimize the fracture treatment and maximize the ratio of productive formation fracture area to volume of fluid pumped by limiting bottomhole pressures to that of the bounding formation.

Selection of Barrier Metals for a Waste Package in Tuff

ABSTRACTThe Nevada Nuclear Waste Storage Investigations (NNWSI) project under the Civilian Radioactive Waste Management Program is planning a repository at Yucca Mountain at the Nevada Test Site for isolation of high-level nuclear waste. Lawrence Livermore National Laboratory is developing designs for an engineered barrier system containing several barriers such as the waste form, a canister and/or an overpack, packing, and near field host rock. In this paper we address the selection of metal containment barriers.

The Mixing of Oil Spills Into the Sea by Breaking Waves

An important pollution-control problem on the high seas is the mixing of an oil spill into the sea caused by breaking waves. This paper presents a theoretical model for determining the amount of oil mixed into the sea by breaking waves. The model is based primarily on probabilistic methods, with experimental observations and data as the foundation. Numerical examples are given. Introduction Due to the strong increase in activity on the Norwegian continental shelf over the past few years and the ensuing danger of a major oil spill accident, national research into the different aspects of removal and containment of oil spills under adverse weather conditions has experienced a concurrent rapid growth.The work presented in this paper is part of a research program being carried out at The Ship and ocean Laboratory (SOL) in Trondheim to gain sufficient knowledge to give proper design criteria for oceangoing oil containment barriers and removal equipment.A problem intimately connected with this is the assessment of the oil distribution with depth under given weather conditions. The primary cause for this vertical distribution of oil is to be found in the presence of breaking waves, which lead to a mixing presence of breaking waves, which lead to a mixing of the oil into the water. This, of course, significantly affects the ability of a mechanical oil boom and/or skimmer to remove oil spills from the sea, and it may well prove to represent the ultimate barrier to such efforts, as they all require the oil to be concentrated near or on the water surface. The importance of this problem has made it highly desirable to try to find problem has made it highly desirable to try to find methods of estimating the vertical distribution of oil in the sea as a function of environmental conditions.At the time we started to study the mixing of oil into the water column, very little work had been done or reported in the literature on this problem. However, we should mention the work by S. Leibovich. He seems to have been the first to attempt to calculate the vertical dispersion of an oil slick into the water column, and his paper served as an inspiration for this work even though we disagreed with his line of attack. In working with this problem we soon realized that if any progress was to be made there were quite a few gaps in the existing knowledge that needed immediate attention. In an attempt to fill in some of the most conspicuous ones, a series of experiments on the effect of breaking waves on an oil slick were performed in one of the wave tanks at SOL.Of particular concern were the effective mixing depths induced by breaking waves passing the oil slick and an estimate of the size distribution of oil droplets formed by the breakup of the oil slick due to the strong mixing created by the passing breaker. Both these factors will influence significantly the expected amount of oil at a certain depth below the surface. During these experiments it was observed that the time constant of the mixing process induced by a breaking wave generally was much smaller than the time periods to be expected between the passing of breaking waves.The mixing mechanism we have described is not the only one present. JPT P. 1113

State of the art in high sea-state oil pollution response capabilities

This paper describes the state-of-the-art approaches to dealing with the two major types of open-water pollution incidents encountered in bad weather — a tanker stranding where the oil is still contained within the tanks, and an actual spillage from a damaged tanker or fixed source. In the stranding case, the cargo off-loading approach is compared with cargo jettisoning (pumping part of the cargo overboard) and stabilization approaches. In the spillage case, the basic approaches that are feasible are skimming and the use of dispersants. The advantages of each are discussed. Systems including large containment barriers are estimated to be less effective than direct-acting skimmers because of the operational control problems in high sea states. Effective direct-acting skimmers are not in wide-spread use at present, although several systems are under development. Dispersant systems are estimated to have the highest sea-state operating capability, particularly aircraft-application systems, which could be effective in conditions up to where a slick is rapidly dispersed through natural wave turbulence.

低速水流上のオイルスリックについて

Model studies of oil containment barriers were conducted in an open channel of 30 cm in width and 45 cm in depth. Currents up to 40 cm/s were used with different oils. Water current speed was measured by a calibrated vane-type turbine meter. Acryl viewing windows in both sides of the tank permitted observations of the flow characteristics. The incipient oil drops from barriers were observed using different oils. With the current set up to about 20 cm, oil was poured slowly onto a flat plate just below the water surface to prevent droplet formation and penetration into the flowing water. The length of the oil slick and some oil thickness were measured along the tank centerline after the oil had “piled up” into the barrier.A simple analysis of the oil slick thickness was made, referd to the current speed and densities.

COMBINED SKIMMER-BARRIER HIGH SEAS OIL RECOVERY SYSTEM1

ABSTRACT This paper describes the development of an oil recovery system to be used in conjunction with the U.S. Coast Guard's high seas oil containment barriers. The system was tested at the EPA's OHMSETT facility in 1975. Its oil recovery capability was shown to be good, with promise for yet better recovery when used on a large spill. Operational practicality was demonstrated in sea trials during May 1976, when the barrier was string towed, catenary towed, and moored in a tidal current. Because of the difficulty of handling large or complicated equipment in offshore conditions, a major design criterion was that the system be as simple as possible. Weir skimmers are particularly simple, but collection of more oil than water or air requires that the weirs follow the vertical motion of the waves. Simplicity and efficiency were achieved by utilizing the wave-following ability of the Coast Guard barrier design. Weirs were built into six struts at the center of a length of barrier, so that barrier deployment results in simultaneous skimmer deployment. To recover oil, it is only necessary to attach pump hoses to the barrier. Three double-acting diaphragm pumps are used. These self-priming pumps were specifically designed to pass any debris that can enter through the three-inch diameter suction hoses. Hydraulic drive was chosen so the pumps could be powered by the Coast Guard's ADAPTS diesel-engine-driven hydraulic power units.

Dynamic Response of Surface-Moored Vertical Barrier to Wave Action by Analog and Digital Simulation

The two-dimensional dynamics of an oil containment barrier, which was designed to have very low tensile loads due to current and waves, were simulated with a theoretical model. The model was solved on both analog and digital computers, and a lab test program conducted to verify the model. For nonlinear problems such as this, for which “exact” solutions do not exist, the analog computer has many advantages, principally rapid parameter studies and convenient plotting output, plus giving the engineer a real time “feel” for the problem. The problem treated here was especially well-suited to analog simulation. Charts and graphs present maximum force and amplitude data, and experimental verification of the solution was obtained from wave tank studies.

OIL SPILL CONTAINMENT AND RECOVERY SYSTEMS

Systems for containment and recovery of oil spills in the offshore environment have been recently developed and tested.Containment SystemA containment barrier system has been designed to maintain structural integrity in 20 ft seas, 3 knot currents and 60 mph winds, and to contain oil in 4 to 5 ft seas and 40 mph winds. The system uses the properties of foam materials to make it lightweight, easily deployable, flexible, and highly wave-conforming. One unique property of the barrier is a special "dynamic keel" which permits the barrier to have static and dynamic stability without a significant weight penalty. The barrier uses foam "memory" to store energy, eliminating the need for auxiliary deployment equipment such as compressors. The barrier is designed so that it can be rapidly deployed to increase containment effectiveness.Recovery SystemA system for recovery of petroleum products from accidental offshore spills has been developed and tested. The testing has included both model testing and prototype testing of a 60 ft long system capable of recovering oil at a rate of 2000 gallons per minute. A 500 gpm system has also been designed.The tests have shown the system capable of recovering spilled oil at high efficiencies (less than 10% water in the recovered oil) at the 2000 gpm rate under environmental conditions ranging from calm to low State 5 seas (8 ft significant wave height) and in currents up to three knots.The oil recovery system is air, truck and ship transportable for rapid deployment to a remote spill location. It is completely self-contained having its own power unit, control system, and pumps. In its preferred deployment configuration it is used with oil containment booms such as the "dynamic keel" barrier, for funnelling the oil to the recovery system.A double weir system is employed to obtain high performance. The system is operated in such a way that oil thickens in front of the primary weir and then further thickens in front of the secondary weir, where it is withdrawn.

Requirement for Open Sea Oil Containment Barriers

ABSTRACTNavy oil pollution control can be divided into open sea and protected water situations. The more rigorous open sea containment requirements are considered in this paper. Containment must be achieved before skimming, removal and other measures can be initiated. The aspects of oil containment considered are spills associated with such ship accidents such as collisions and groundings and the subsequent ship salvage operations in the open sea. The required barrier characteristics and the deployment and recovery thereof are treated.

N S Savannah Containment Integrity, Its Measurement and Improvement

Leak-rate tests for the N S Savannah were initially conducted at pressures lower than those encountered in a maximum credible accident, requiring extrapolation to predict the release of radioactivity. Improved test procedures have reduced extrapolation errors by making it possible to increase the test pressure to 60 lb/in.2 Leak rates determined by both absolute and reference methods show close agreement. The most extensive Savannah containment tests are described. These tests showed that the most significant leakage was through the containment electrical penetrations. Replacement of the original penetration fittings with an improved design using hermetically sealed conductors is eliminating this leakage. Significant leaks were also detected at the seats of valves forming a single containment barrier. Installation of double valves and valves using seats with teflon inserts is eliminating this leakage.