Return to Sender: System Maintenance, Reverse Logistics, and Hazardous Materials Transportation

by Scott Gunderson, Portland, Oregon
 

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Design for Decontamination
Decontamination may not be a trivial task, both in terms of required effort and the consequences of incomplete work. A checklist approach to design does not adequately summarize the sample space for risk analysis, but the nature of contamination, the purpose of component removal and the level of expected maintenance provide a framework for decisions. Analysis of hazardous material inputs and outputs should trace the flows through the system and the component designated for removal and shipment. Flow analysis of hazardous materials should include transformations, reactions, byproducts and residues. In the case of gases, design for purging with inert gas and bleeding may remove chemical and pressure hazards. In the case of liquids, design for flushing with water or applicable neutralizers followed by draining may remove hazards, but internal "traps" may prevent complete decontamination or provide a source of false alarms if water leaks in transit. Design for disassembly and drying may eliminate this problem, or capping and plugging inlets and drains may provide adequate containment for liquids. Disassembly for removal, and capping or plugging openings, may provide similar resolution for solids. Decontamination, if complete, can eliminate the initial source of risk in the fault tree and prevent the top event of hazardous materials release in transit. This achieves the transportation goal of hazard elimination as the highest priority in the system safety engineering hierarchy.

Verifying Decontamination
Use of qualitative or quantitative methods of verifying decontamination prior to shipment will depend on managerial risk tolerance, and desired or required time for return to service. Qualitative methods include visual review or physical wiping for evidence of solid or liquid residues. Quantitative methods range from on-site testing such as pH verification for non-corrosive surfaces, to lengthier off-site analysis of wipe tests to verify the absence of fluoride or chloride [Ref. 7]. In terms of reducing third-party liability for transfer to other component handlers, and also verifying safety beyond the scope of hazardous materials transportation compliance, off-site analysis of wipe tests can confirm that component surfaces meet "health-based" levels [Refs. 9, 13]. These represent the highest levels of decontamination and due diligence to recognized standards. The oral and dermal levels, respectively, for arsenic at 0.05 mg/100 cm2 and 0.33 mg/100 cm2 are not qualitatively verifiable through visual inspection of component surfaces.

Conclusion
As economic and competitive pressures increase for system owners and operators, reverse logistics can reduce the cost of system ownership by use of central or contract maintenance personnel at offsite locations [Ref 2]. This effectively extends the system across multiple locations, requiring consideration of transportation risks as part of the system risk analysis. Transportation of components contaminated with hazardous materials increases risk and complicates the analysis. However, initiatives such as design for regulated shipment and design for decontamination can permit the integration of reverse logistics into the system life cycle, while reducing the potential for hazardous materials events during component transportation.

References

  1. 49 CFR 172.
  2. Blanchard, B.S. Logistics Engineering and Management. 5th ed. Upper Saddle River, New Jersey: Prentice Hall, 1998.
  3. Blanchard, B.S. and W.J.Fabrycky. Systems Engineering and Analysis. 3rd ed. Upper Saddle River, New Jersey: Prentice Hall, 1998.
  4. Fleischmann, M. Quantitative Models for Reverse Logistics. Berlin: Springer, 2001.
  5. Kumar, U.D. and J. Crocker. "Maintainability and Maintenance – A Case Study on Mission Critical Aircraft and Engine Components." In Case Studies in Reliability and Maintenance. W.R. Blischke and D.N.P. Murthy, eds. Hoboken, New Jersey: Wiley, 2003.
  6. Peters, G.A. and B.J.Peters. "The Expanding Scope of System Safety." In Journal of System Safety, Vol. 38, No. 2, 2002, pp. 12-16.
  7. Semiconductor Equipment and Materials International. "Decommissioning Task Force Report (Draft)." Arizona State University, Construction, Research and Education for Advanced Technology Environments.
  8. Semiconductor Equipment and Materials International. "SEMI S2-0200 Environmental, Health, and Safety Guideline for Semiconductor Manufacturing Equipment." San Jose, California. 2001.
  9. Semiconductor Equipment and Materials International. "SEMI S12-0298 Guidelines for Equipment Decontamination." San Jose, California. 1998.
  10. Semiconductor Equipment and Materials International. "SEMI S16-0600 Environmental, Health, and Safety Guidelines for Semiconductor Manufacturing Equipment Disposal." San Jose, California. 2000.
  11. United States Department of Transportation. "49 CFR Part 107, et al. Hazardous Materials: Enhancing Hazardous Materials Transportation Security: Interim Final Rule." In Federal Register, Vol. 68, No. 86, May 5, 2003.
  12. United States Department of Transportation. "49 CFR Part 172. Hazardous Materials: Security Requirements for Offerors and Transporters of Hazardous Materials: Final Rule." In Federal Register, Vol. 68, No. 57, March 25, 2003.
  13. United States Environmental Protection Agency, Integrated Risk Information System, http://www.epa.gov/iris/index.html.
  14. United States National Transportation Safety Board. "Aircraft Accident Report: In-Flight Fire and Impact With Terrain Valujet Airlines Flight 592 DC-9-32, N904VJ Everglades, Near Miami, Florida May 11, 1996." NTSB Report Number AAR-97-06, 1997.

 

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