Hanford Single-Shell Tank Leak Causes and Locations - 241-SX Farm Page: 21 of 611
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RPP-RPT-54910, Rev. 0
be assumed that the 18 F design temperature was applicable to the fabrication of ASTM A 283
carbon steel at the time of SX Farm construction.
The SX Farm Blue Print File (BPF) No. 4961 Chemical and Physical Test Reports for steel plate
was reviewed and found to meet the carbon and magnesium limits defined in HW-4957; carbon
0.26% maximum and manganese 0.60% maximum. Carbon ranged from 0.07 to 0.15% with an
average ~0.11%. Manganese ranged from 0.04% to 0.48% with an average ~0.43%. The one
report of manganese at 0.04% appeared to be an outlier as the lowest above that was 0.39%. All
of the 25 sheets with a total of 40 determinations were notarized and approved by the prime
contractor.
A review of toughness and the ductile-to-brittle transition temperature for carbon steels
(designated as "impact transition temperature") in Mark's Standard Handbook for Mechanical
Engineers, Tenth Edition, indicates that carbon content can have a significant effect. Decreased
carbon content not only raises the propagation energy needed for crack growth but also lowers
the temperature for transition from ductile-to-brittle behavior (reference Fig 6.2.11 in Marks),
suggesting that the B&PVC, Section VIII, low temperature service limit may be lower than what
could be expected for steel of the vintage used in SX Farm construction. The concentrations of
carbon and trace impurities and their effect on this property are not specifically known, and low
temperature impact resistance could only be determined reliably by impact testing of actual tank
liner specimens.
Below the transition temperature, the metal loses its ability to absorb forces such as induced
loads, or the impact of falling objects without fracturing. In these circumstances it is possible for
micro-fissures or hairline cracks to be created. Later, when the metal is subjected to high stress,
it might be possible for the cracks to propagate through the metal, or possibly subject the
weakened areas to increased corrosion.
Any low temperatures experienced during construction at or less than the 18 F allowable
temperature where impact loading (e.g. a dropped tool or piece of equipment from scaffolding)
had the potential for creating micro-fissures may have triggered fissures in the steel liner.
The possible variability of liner steel from either different runs from the same supplier, or
because of multiple suppliers, could affect the resistance to low temperatures.
3.2 IN-TANK DATA
The general information in this section is further developed and applied to the leaking tanks in
later sections of each tank segment to understand implications of the conditions that could affect
liner leaks and identify possible liner leak locations.
3.2.1 Liquid Level
The following is an excerpt from RPP-ENV-39658:
"Originally liquid levels were measured using pneumatic dip tubes (HW-10475-C,
Hanford Technical Manual Section C, page 908). This practice was later replaced and a
manual tape with a conductivity electrode was used to detect the liquid surface (H-2-3-10
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Girardot, Crystal L. & Harlow, Donald G. Hanford Single-Shell Tank Leak Causes and Locations - 241-SX Farm, report, January 8, 2014; Richland, Washington. (https://digital.library.unt.edu/ark:/67531/metadc870771/m1/21/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.