Combustible Dust Testing

Laboratory testing to quantify dust explosion & reactivity hazards

Flammable Gas & Vapor Testing

Laboratory testing to quantify explosion hazards for vapor and gas mixtures

Chemical Reactivity Testing

Laboratory testing to quantify reactive chemical hazards, including the possibility of material incompatibility, instability, and runaway chemical reactions

DIERS Methodology

Design emergency pressure relief systems to mitigate the consequences of unwanted chemical reactivity and account for two-phase flow using the right tools and methods

Deflagrations (Dust/Vapor/Gas)

Properly size pressure relief vents to protect your processes from dust, vapor, and gas explosions

Effluent Handling

Pressure relief sizing is just the first step and it is critical to safety handle the effluent discharge from an overpressure event

Thermal Stability

Safe storage or processing requires an understanding of the possible hazards associated with sensitivity to variations in temperature

UN-DOT

Classification of hazardous materials subject to shipping and storage regulations

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Biological

Model transport of airborne virus aerosols to guide safe operations and ventilation upgrades

Radioactive

Model transport of contamination for source term and leak path factor analysis

Fire Analysis

Model transport of heat and smoke for fire analysis

Flammable or Toxic Gas

transport of flammable or toxic gas during a process upset

OSS consulting, adiabatic & reaction calorimetry and consulting

Onsite safety studies can help identify explosibility and chemical reaction hazards so that appropriate testing, simulations, or calculations are identified to support safe scale up

Mechanical, Piping, and Electrical

Engineering and testing to support safe plant operations and develop solutions to problems in heat transfer, fluid flow, electric power systems

Battery Safety

Testing to support safe design of batteries and electrical power backup facilities particularly to satisfy UL9540a ed.4

Hydrogen Safety

Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen

Spent Fuel

Safety analysis for packaging, transport, and storage of spent nuclear fuel

Decommissioning, Decontamination and Remediation (DD&R)

Safety analysis to underpin decommissioning process at facilities which have produced or used radioactive nuclear materials

Laboratory Testing & Software Capabilities

Bespoke testing and modeling services to validate analysis of DD&R processes

Nuclear Overview

Our Nuclear Services Group is recognized for comprehensive evaluations to help commercial nuclear power plants operate efficiently and stay compliant.

Severe Accident Analysis and Risk Assessment

Expert analysis of possible risk and consequences from nuclear plant accidents

Thermal Hydraulics

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Environmental Qualification (EQ) and Equipment Survivability (ES)

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Laboratory Testing & Software Capabilities

Testing and modeling services to support resolution of emergent safety issues at a power plant

Adiabatic safety calorimeters (ARSST and VSP2)

Low thermal inertial adiabatic calorimeters specially designed to provide directly scalable data that are critical to safe process design

Other Lab Equipment (DSC/ARC supplies, CPA, C80, Super Stirrer)

Products and equipment for the process safety or process development laboratory

FERST

Software for emergency relief system design to ensure safe processing of reactive chemicals, including consideration of two-phase flow and runaway chemical reactions

FATE

Facility modeling software mechanistically tracks transport of heat, gasses, vapors, and aerosols for safety analysis of multi-room facilities

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Recent Posts

Innovative Hydrogen Removal Design, Shielded Containers: Nuclear Plant

Posted by The Fauske Team on 03.16.15

By James P. Burlebach, PhD, Manager, Waste Technology & Post-Fukushima Services, Fauske & Associates, LLC

Nuclear waste that contains metallic spent nuclear fuel pieces or sludge generates hydrogen as a product of chemical reactions and from radiolysis of water. These waste materials may be stored in shielded boxes with filtered vents for removal of the hydrogen to prevent formation of flammable gas mixtures.  Bore holes drilled through shielding add resistance to hydrogen removal that can allow unwanted accumulation of hydrogen. 

The innovative work described here was performed by Fauske & Associates, LLC, (FAI) a wholly owned subsidiary of Westinghouse Electric Company, LLC, in partnership with Sellafield, Ltd. In partnership, we have conceived, modeled, and experimentally verified an effective method for hydrogen removal from shielded boxes with significant hydrogen generation rates. This innovation minimizes the number of filters required for passive storage of spent metallic nuclear fuel pieces and other hydrogen-generating waste streams.

Many commercially available filters are suitable for removal of hydrogen from unshielded nuclear waste containers such as 200 L drums. The rate of hydrogen removal through a filter varies with filter size and materials. The key filter specification provided by the manufacturer is the filter coefficient, expressed in units of moles hydrogen per second per mole fraction difference across the filter. The size of filter for a given application is chosen based on the hydrogen source rate and the required upper limit for hydrogen concentration. 

Shielded containers are made of much thicker materials than conventional containers. In order for the hydrogen to escape from the container, it must first pass through a channel drilled into the shielding material (the flow path) then through the filter and out into the surrounding atmosphere. The rate at which hydrogen escapes from the container depends upon the difference in hydrogen concentration between the two sides of the filter. Because shielding keeps the fuel, and the bulk of the hydrogen, away from the filter, the hydrogen flow rate through the filter is reduced. So, removal of hydrogen through any filter is less effective in a shielded container than it would be for the same filter on an unshielded container. For systems where the hydrogen source is chemical reactions, the source rate is typically much larger than from radiolysis, and this might make hydrogen removal impractical.

For example, a shielded container with a bore hole of 20 mm diameter and 300 mm length drilled through the shielding would allow hydrogen to escape at only one-tenth the rate that it would in an unshielded container (in engineering terms, the system efficiency is 10%). As a consequence, the number of filters required would increase tenfold.

The key to hydrogen removal from a shielded container is to reduce the flow resistance such that the filter is the main resistance. We have developed an innovative arrangement to promote hydrogen flow to the filter via a pair of bore holes in the shielded container lid, Figure 1. This design takes advantage of buoyancy induced natural circulation. Gas from the container flows up one of the bore holes into the plenum beneath the filter and then down the other bore hole, returning to the container.  We have performed modeling for this design which demonstrates that the efficiency of the double bore system can be in the range of 80% to 90%.  This high efficiency minimizes the number of vents required.

 Double bore hole arrangement with single filter

Figure 1. Double bore hole arrangement with single filter

For additional information, be sure to stop by Dr. Burelbach's poster session titled  Innovative Hydrogen Removal Design for Self-Shielded Containers at the WM2015 Conference this Wednesday, March 18 from 1:30 - 5:00 in the first floor foyer of the Phoenix Convention Center, or contact Dr. Burelbach at 630-887-5221 or burelbach@fauske.com

Nuclear plant, nuclear safety

Subscribe to FAI's "Nuclear Technical Bulletins"

Preventing Phenolic Resin Reactor Accidents: "Easy to Use" Procedure for Checking Adequacy of Emergency Relief Vent Sizes

               

Topics: nuclear plant, nuclear safety, nuclear waste

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