Lim J.,Fauske and Associates |
Ozar B.,Fauske and Associates |
Lee S.J.,Fauske and Associates
Annals of Nuclear Energy | Year: 2017
Enhancements are made in the Boiling Water Reactor (BWR) version of MAAP 5.04 to consider ex-vessel Control Rod Drive (CRD) housing heat transfer and melting. The in-vessel CRD tube model is extended below the reactor vessel and conduction and radiative heat transfer between the lower head, CRD tubes, pedestal gas and pedestal wall are considered. The possibility of corium melt flowing into collapsed CRD tubes and causing creep rupture of CRD tubes outside the reactor vessel, leading to vessel failure, is considered. Lastly, ex-vessel CRD tube melting due to the corium jet exiting the breached reactor vessel after vessel failure is considered. The BWR Station Blackout (SBO) scenario was simulated using the new code. The results show that explicitly modeling the ex-vessel CRD tube heat transfer did not affect the time of vessel failure. Also, vessel failure due to corium ingress into ex-vessel CRD tubes was not predicted. A small, but nontrivial mass of steel from ablated ex-vessel CRD tubes was added to the debris bed on the pedestal floor after vessel failure. © 2017 Elsevier Ltd
Turkevich L.A.,Centers for Disease Control and Prevention |
Dastidar A.G.,Fauske and Associates |
Hachmeister Z.,Fauske and Associates |
Lim M.,Fauske and Associates
Journal of Hazardous Materials | Year: 2015
Following a previous explosion screening study, we have conducted concentration and ignition energy scans on several carbonaceous nanopowders: fullerene, SWCNT, carbon black, MWCNT, graphene, CNF, and graphite. We have measured minimum explosive concentration (MEC), minimum ignition energy (MIE), and minimum ignition temperature (MITcloud) for these materials. The nanocarbons exhibit MEC 101-102g/m3, comparable to the MEC for coals and for fine particle carbon blacks and graphites. The nanocarbons are confirmed mainly to be in the St-1 explosion class, with fullerene, at KSt200bar-m/s, borderline St-1/St-2. We estimate MIE 102-103J, an order of magnitude higher than the MIE for coals but an order of magnitude lower than the MIE for fine particle graphites. While the explosion severity of the nanocarbons is comparable to that of the coals, their explosion susceptibility (ease of ignition) is significantly less (i.e., the nanocarbons have higher MIEs than do the coals); by contrast, the nanocarbons exhibit similar explosion severity to the graphites but enhanced explosion susceptibility (i.e., the nanocarbons have lower MIEs than do the graphites). MITcloud > 550°C, comparable to that of the coals and carbon blacks.
Worsfold S.M.,Dalhousie University |
Amyotte P.R.,Dalhousie University |
Khan F.I.,Memorial University of Newfoundland |
Dastidar A.G.,Fauske and Associates |
Eckhoff R.K.,University of Bergen
Industrial and Engineering Chemistry Research | Year: 2012
This paper explores the explosion characteristics of three nontraditional dusts: nanomaterials, flocculent materials, and hybrid mixtures. Nanomaterials have a high likelihood of explosion with minimum ignition energies potentially less than 1 mJ. These low ignition energies may therefore allow nanomaterials to ignite due to electrostatic sparks, collision, or mechanical friction. The severity of nanomaterial explosions is affected by agglomeration and coagulation of the particles. Flocculent materials with a high length-to-diameter ratio exhibit explosion behavior patterns similar to those for spherical dusts. The length of flocculent particles plays a role in explosion likelihood which is not yet fully understood. High voltage discharge during the electrostatic flocking process is a common flocculent ignition hazard. Hybrid mixtures of a combustible dust and a flammable gas/vapor display a higher explosion severity and a lower minimum explosible concentration than that of the dust alone. Violent hybrid explosions may occur even if the dust and the gas/vapor are below their respective lean limit concentrations. © 2012 American Chemical Society.
Kurko K.,Fauske and Associates
Design Institute for Emergency Relief Systems (DIERS) 2015 - Topical Conference at the 2015 AIChE Spring Meeting and 11th Global Congress on Process Safety | Year: 2015
When conducting relief sizing calculations for reactive systems, experimental data is of paramount importance. Experimental techniques for gathering the necessary kinetic data highlighting VSP2 (Vent Sizing Package 2) and ARSST (Advanced Reactive System Screening Tool) testing will be outlined. In addition, the principles behind the system classifications (vapor, gassy and hybrid) will be outlined with example experimental data sets. Relief sizing calculations and source term considerations for each system will be discussed. Two-phase flow and experimental techniques for determining flow regime (vapor, churn, bubbly or homogeneous flow) will be presented with the goal of providing the audience with a simple comprehensive experimental approach to designing relief systems.
Kwasny R.,Fauske and Associates
Process Safety Progress | Year: 2012
Drying is an especially hazardous operation. To make this operation safer, it is critical to understand the hazards associated with decomposition, fire, and explosion including worst-case scenarios resulting from operational and control failures. This article describes the tests and standards required to prevent accidents when handling bulk powders and dusts. The outcome of these tests and standards is to quantify the risks for normal and upset conditions and to implement adequate safeguards to prevent accidents. © 2012 American Institute of Chemical Engineers (AIChE).
Dale D.,Fauske and Associates
Institution of Chemical Engineers Symposium Series | Year: 2012
To demonstrate safe transportation the United Nations guidelines1 define seven classification groups that are determined by performing specific tests. Self-reacting substance should be subject to these testing criteria and classification procedures, and classified into one of the seven types (A-G) which relates their hazard to an allowable quantity/package size for transport. This paper presents an alternative methodology to the prescribed UN testing regime by utilising one easy to perform lOg Advanced Reactive System Screening Tool (ARSST) test to produce the necessary information that allows the packaging classification type to be determined. The UN guidelines allow such alternative procedures to be used provided adequate correlation has been obtained with the classification tests on a representative range of substances and examples of this correlation will be given. © 2012 IChemE.
Dastidar A.G.,Fauske and Associates
Process Safety Progress | Year: 2015
The National Fire Protection Agency (NFPA) has a standard on explosion protection systems, NFPA 69, which provides guidelines on effective inerting to prevent explosions. The standard specifies that for inerting to be effective the oxygen concentration must be kept below the Limiting Oxygen Concentration (LOC). It then goes on to specify that the ASTM International standard E2079 be used to establish the LOC. The shortcoming of this approach is that ASTM E2079 only applies to combustible gases and vapors and not combustible dusts. As a result of this deficiency ASTM International has just introduced a new standard, ASTM E2931, Standard Test Method for Limiting Oxygen (Oxidant) Concentration of Combustible Dust Clouds. This paper discusses the nuances of this standard and compares experimental results between the 20-L chamber and the 1-m3 chamber. Differences in the test results between the vessels and between test methods may have safety ramifications to the end user of the data. The large variation present in the repeatability and reproducibility of the LOC means that the current common practice of using a 2% safety margin for particle inerting (the least stringent of the inerting methods) may be insufficient to ensure dust cloud explosion mitigation. It is possible that additional study and improved laboratory proficiency as the test standard matures will bring down these repeatability and reproducibility errors. Additionally, if LOCs are reported in Safety Data Sheets without accompanying information regarding the test method or test vessel size used, the mitigation strategy may not provide adequate protection. © 2015 American Institute of Chemical Engineers.
Theis A.E.,Fauske and Associates
Journal of Loss Prevention in the Process Industries | Year: 2014
A tragic explosion resulting from a runaway chemical reaction occurred at the T2 Laboratories, Inc. facility in December 2007. The U.S. Chemical Safety Board (CSB) completed an incident investigation of the T2 explosion, identifying the root cause as a failure to recognize the runaway reaction hazard associated with the chemical it was producing. Understanding the consequences of process upset conditions is critical to determine risk. This paper will focus on lessons learned from this incident including a comprehensive hazard assessment for reactive chemicals as well as proper collection and application of adiabatic calorimetry data to characterize the chemical reaction and determine appropriate mitigation strategies. Examples will be provided to establish safer operating conditions, implement safeguards and reduce the overall risk. © 2014 Elsevier Ltd.
Fauske H.K.,Fauske and Associates
Process Safety Progress | Year: 2013
This article describes a simple cost effective alternative to the United Nations tests for determining the Self Accelerating Decomposition Temperature (SADT) for transporting reactive chemicals. The proposed method uses simple calorimetry results together with well known heat loss models. Some detailed results and analysis are included that show (a) the proposed method gives essentially identical results as the United Nations H.1, H.2, and H.3 results, (b) the proposed method is not sensitive to the shape of the reactant, and (c) the proposed method can be easily used to determine results as a function of various conditions. This alternative method provides correct SADT of the substance as packaged for transport, and is, therefore, consistent with suggestions by the United Nations "Recommendation on the Transport of Dangerous Goods." © 2013 American Institute of Chemical Engineers.
Fauske and Associates | Date: 2012-09-04
Calorimeters, namely adiabatic calorimeters; Calorimeter replacement parts.