Hanford Review of Double-Shell Tank Construction

Double-shell waste storage tanks located at the Hanford site in Washington state store millions of gallons of mixed waste which contains hazardous and radioactive constituents. To monitor their condition and ensure continued viability, these tanks are inspected periodically through a comprehensive integrity program. Tank configuration variations and construction conditions present several access challenges that will need to be overcome in the future. In August 2012, material was seen during routine visual inspection of double-shell tank (DST) 241-AY-102 on the annulus floor. Further investigation confirmed primary tank bottom failure. As discussed in the leak assessment report for tank AY-102, bulges in the secondary liner led to deterioration of refractory during post-weld heat treatment. Refractory degradation likely created unsupported areas of the primary bottom. This combined with welding rework during construction left residual stresses that may have accelerated corrosion and contributed to the primary tank failure. The exact failure location and damage mechanism are both still undetermined. Further detail of access challenges and the resulting as-built configuration that an inspection system would encounter will be presented in a graphic manner. Details obtained through extensive tank construction records review will add further perspective of materials utilized, construction practices, and final condition of the Hanford double-shell tanks that we are now tasked with effectively monitoring and managing today.

References
  1. J.K. Engeman, et al., “Tank 241-AY-102 Leak Assessment Report,” Washington River Protection Solutions LLC Company Report, RPP-ASMT-53793, Rev. 0, November 2012.
  2. T.J. Barnes, et al., “241-AY-101 Tank Construction Extent of Condition Review for Tank Integrity,” Washington River Protection Solutions LLC Company Report, RPP-RPT-54817, Rev. 0, August 2013.
  3. T.J. Barnes, et al., “241-AZ Tank Farm Construction Extent of Condition Review for Tank Integrity,” Washington River Protection Solutions LLC Company Report, RPP-RPT-54818, Rev. 0, August 2013.
  4. T.J. Barnes, et al., “241-SY Tank Farm Construction Extent of Condition Review for Tank Integrity,” Washington River Protection Solutions LLC Company Report, RPP-RPT-54819, Rev. 0, July 2013.
  5. T.J. Barnes, et al., “241-AW Tank Farm Construction Extent of Condition Review for Tank Integrity,” Washington River Protection Solutions LLC Company Report, RPP-RPT-55981, Rev. 0, November 2013.
  6. T.J. Barnes, et al., “241-AN Tank Farm Construction Extent of Condition Review for Tank Integrity,” Washington River Protection Solutions LLC Company Report, RPP-RPT-55982, Rev. 0, February 2014.
  7. T.J. Barnes, et al., “241-AP Tank Farm Construction Extent of Condition Review for Tank Integrity,” Washington River Protection Solutions LLC Company Report, RPP-RPT-55983, Rev. 0, April 2014.
  8. ASME BPVC Section VIII (1971), “Rules for Construction of Pressure Vessels” (New York, NY: ASME).
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