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Hanford begins removing waste from 24th single-shell tank
The Department of Energy’s Office of Environmental Management said crews at the Hanford Site near Richland, Wash., have started retrieving radioactive waste from Tank A-106, a 1-million-gallon underground storage tank built in the 1950s.
Tank A-106 will be the 24th single-shell tank that crews have cleaned out at Hanford, which is home to 177 underground waste storage tanks: 149 single-shell tanks and 28 double-shell tanks. Ranging from 55,000 gallons to more than 1 million gallons in capacity, the tanks hold around 56 million gallons of chemical and radioactive waste resulting from plutonium production at the site.
Rob P. Rechard
Nuclear Technology | Volume 190 | Number 2 | May 2015 | Pages 127-160
Technical Paper | Reactor Safety | doi.org/10.13182/NT14-41
Articles are hosted by Taylor and Francis Online.
This paper, Part II of two companion papers, demonstrates the concepts for evaluating the criticality scenario class after closure of a geologic repository for spent nuclear fuel (SNF) and high-level radioactive waste. As an example, the low-probability rationale used to exclude consideration of criticality in the performance assessment of the potential Yucca Mountain (YM) repository in southern Nevada is summarized. The Yucca Mountain Project (YMP) presented a quantitative rationale that the probability of criticality inside breached waste containers was <10−4 over 104 yr to show that criticality was not necessary to consider. The dominant probability occurred when neutron absorber material was inadvertently left out for a package disposing of SNF from experimental reactors owned by the U.S. Department of Energy. In addition, this paper develops a quantitative estimate of the low probability of criticality outside the package in either the engineered or geologic barrier to complement the qualitative rationale developed by YMP. Because consequence may also be used as the basis of screening, consequences of criticality at the potential YM repository are roughly estimated, based on results from the literature. The consequences are then combined with the low-probability estimates as a complementary cumulative distribution function to place the corresponding estimated consequences in context and, thereby, provide further perspective on excluding the criticality scenario class.