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Peristaltic Crawler for the Removal of Radioactive Plugs

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Peristaltic Crawler for the Removal of Radioactive Plugs. Presented by: Lee Brady DOE Fellow. Overview . Problem Statement Motivation Proposed Solution Design Metrics Mechanical Designs Vs. Pneumatic Design Prototype Characterizing Sludge Final Design Fault Tolerant

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Presentation Transcript
  • Problem Statement
  • Motivation
  • Proposed Solution
  • Design Metrics
  • Mechanical Designs Vs. Pneumatic Design
  • Prototype
  • Characterizing Sludge
  • Final Design
  • Fault Tolerant
  • Modeling and Engineering Analysis
  • Force Analysis
  • Tether Length?
  • Environmental Impact
  • Future Work
  • Acknowledgements
problem statement
Problem Statement
  • The Manhattan Project left behind an estimated 55 million gallons of radioactive waste in Hanford, WA
  • 69 of 149 single-shell tanks have begun to leak
  • Complete transfer into secure double-shell tanks is required by 2040
  • Delays due to blockages in transfer pipelines delay the process further
    • Increasing costs
    • Threatening the Environment
  • Radioactive materials can reach the Columbia River in as little as 3 years
  • 270 billion gallons of contaminated soil and ground water in neighboring aquifers
  • Previously tested unplugging technologies failed to achieved satisfying results
    • Unplugging capabilities drastically reduce as the distance to the plug increases
proposed solution
Proposed Solution
  • A crawler that will crawl to the plug and apply abrasive techniques to remove the plugs
  • Thus reducing the distance to the plug
design metrics
Design Metrics
  • Based on Hanford pipelines the crawler and components must:
    • Fit in a pipe having inner diameter of 3”
    • Negotiate through 90˚ bends w/ turning radius of 4.25”
    • Be able to pull its own weight including weight of tether.
    • Never exceed 300 psi
    • Be radiation resistant for a10 Gy/hr environment
    • Be capable of removing clogs that exist in pipelines
prototype construction
Prototype Construction
  • 6061 Aluminum
  • 1.5” Hoover Vacuum Hose
  • 2” Black Duct Hose
  • Spiral Hose
  • Boot Clamps
  • Inner Tubes
  • Pressure Nozzle Bracket
characterizing sludge
Characterizing Sludge
  • Simulants can be grouped into three major categories:
    • sludge simulants (most prominent)
    • hardpan waste simulants
    • saltcake waste simulants
  • The Pacific Northwest National Laboratory has extensive documentation on different waste simulants
    • Non-hazardous to the environment
    • Formulated to resemble the physical properties of radioactive plugs that occur in the pipelines
  • The mechanical strength, porosity, dissolution rate, solubility and thermal conductivity of the simulant are studied by DOE scientists.
  • Due to availability, Bentonite Clay, a sludge type simulant was used for testing of the crawler’s unplugging tool.
final crawler design of bodies
Final CrawlerDesign of Bodies
  • 516 Stainless Steel Bodies
final crawler design of bellows
Final CrawlerDesign of Bellows
  • 516 Stainless Steel custom made, edge welded bellow
    • Duraflex, Inc
    • 8:1 collapse ratio
fault tolerant design
Fault Tolerant Design
  • Inner Tube Ruptures
  • Crawler Jamming
  • Inner/Outer Bellow Ruptures
  • Rim Separation
cost analysis
Cost Analysis

Labor Costs

  • According to ThermoFisher Company, a commercial charge couple device(CCD) camera could last one hour at 300 Gy/hr. (Hanford = 10 Gy/hr)
  • The exact life of a CCD camera in a 10Gy/hour environment is unknown.
  • However, another radiation hardened inspection device can survey where the blockage is in the pipeline.
  • After, the peristaltic crawler can be sent in once the location and distance of the plug is known.
stress on inner tubes
Stress on Inner Tubes
  • Polyurethane 5511 PSI Ultimate Stress
tether length
Tether Length?
  • 300 PSI bellow = 345 lbs of pulling force
  • 100 ft of final tether ~ 15 lbs
    • Four 1/16” and One 1/8” pneumatic tubes
    • One .48” OD Hydraulic Hose
    • One1/16” S.S winch cable
  • 345 lbs = 2300 feet (neglecting friction)
  • 2300 feet is improbable
    • Due to frictional forces inside the pipeline and how the 90 degree elbows affect the force required to pull the tether.
    • More feasible for unplugging the pipes in treatment facilities
      • Few hundred feet
anchoring force
Anchoring Force
  • To preserve the realistic integrity of the parts and mathematical stability of the model thickness equates to .38 inches.
environmental impact
Environmental Impact
  • While the crawler is in a vacuum stage it is possible that it may pull contaminated air out into the atmosphere.
    • An air filter used in the nuclear industry will prevent contaminated air from expelling into the environment
  • The crawler and tether will be radioactive the instant it is introduced to the pipeline.
  • To prevent the contamination of objects outside the pipeline, the crawler will be contained in a lead housing with a reeling system
  • The crawler will be stored inside this unit and removed from the site safely.
future work
Future Work
  • The successful removal of a plug is based on two things:
    • Tool Effectiveness
    • Sufficient Path for Removed Debris travel to the rear of the crawler
  • A hydraulic pressure nozzle was used in the project but may not be the most effective tool against certain types of plugs.
  • Implementation of a mechanical type abrasive tool.
    • Can be powered by hydraulics as to avoid the use of circuitry.
future work1
Future Work
  • Four-piston type mechanism mounted on the perimeter of the front rim, the nozzle will be able to adjust the aim of the trajectory of the nozzle plume.
  • By using pneumatics the individual pistons can be adjusted to aim the crawler head left, right, up or down.
  • The four-piston feature may also improve the maneuverability of the crawler.
  • Peristaltic Crawler was designed under all the design metrics
    • Versatile platform that can implement more powerful unplugging tools
    • Simple, Robust and Fault Tolerant
  • ARC Faculty
    • Leonel Lagos, Ph.D, PMP
    • Tomas Pribanic, MS
    • Dwayne McDaniel, Ph.D, PE
    • Seckin Gokaltun, Ph.D
    • Amer Awwad, PE
  • Prof. Rick Zicarelli
  • Engineering Colleagues