The Hanford Tanks Environmental Impacts and Policy Choices (1996) / Chapter Skim
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3 Findings
3 Findings
Pages 20-43
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From page 20... ...
TECHNOLOGY UNCERTAINTIES With the exception of the No Action and Long-Term Management Alternatives, He technologies for the tariff waste remediation alternatives presented in the DElS have not been demonstrated for He Hanford tank wastes. Therefore, not only is the effectiveness of the alternatives unknown, but whether Hey are feasible at all for use with the tank wastes is also largely unlmown The uniqueness, complexity, and enormous scale of the Hanford tank waste problem make the remediation task unprecedented In DOE's experience.
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From page 21... ...
However, this is not the case with the Hanford tank wastes for the In-Situ and Ex Situ No Separations Alternatives and is not certain to be the case for He Ex Situ/In Situ Combination, the Ex Situ/ Situ Combination Variation, arid the Ex Situ Intermediate Separations Alternatives. In these alternatives, the waste feed to the vitnfier will be alkaline, much larger In quantity than any in previous expenence, and of variable composition.
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From page 22... ...
The higher cost estimates for certain alternatives are driven In part by significant uncertainties In waste amount, cost of waste recovery and processing, numbers of waste canisters produced, disposal repository acceptance criteria, and number and timing of repository operations. As an example, estimates of fees at repositories for Me ex situ alternatives range from $0.6 billion to $211 billion (DENS, Vol.
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From page 23... ...
Because of the many uncertainties about Me tank wastes, contracts may have to be repeatedly modified to reflect new information. There is a potential for enormous cost increases as the program develops.
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From page 24... ...
In order to reduce these uncertainties, the following steps must be talcen on a priority basis: · The wastes must be eilaract~ized expeditiously, · Viable, competitive alternatives for dealing with various types of wastes must be defined; · Thme competitive alternatives must be tested following the proven engineering practices that begins at the laboratory scale and progresses to bench and pilot scales; arid · Rigorous trade-off studies using technically defensible criteria at each stage along this path are needed to produce defensible selections of processes for TWRS."
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From page 25... ...
The decision by DOE and the Washington State Department of Ecology to adopt a phased approach for removing and treating the tank wastes is clearly a prudent approach In a situation such as Hat at the Hanford Site, where there are many uncertainties. A phased decision strategy, as recommended by He committee, allows for process improvements to be made based on experience and provides a credible basis for estimating the perfonnance of filture operations.
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From page 26... ...
Regulation of the Hanford tanks under Environmental Protection Agency (EPA) rules written for ordinary chemical wastes is such a case.
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From page 27... ...
Nuclear Regulatory Commission as incidental waste not subject to their regulatory jurisdiction; · Any residual material left in the tanks after practical retrieval operations will be suitable for in situ tactic closure, i.e., how clean is clean; · The bansuranic waste can be blended with high-level waste for disposal in the geologic repository if it is detennined that separation of some, or all, of the in-tank transuranic waste for disposal at the Waste Isolation Pilot Plant is more costly or presents significant safety or environmental hazards; · The projected volumes of immobilized 0th-level waste in the selected size canisters will, in fact, be accepted for the geologic repository, and that the expected and bounding fees for permanent disposal of waste will be established expeditiously, and · Multiple, nonconforming glass compositions, significantly different than Defense Waste Processing Facility and West Valley Project borosilicate glass, are to be pursued despite risks that regulators might not accept one or more ofthese glasses." (U.S. Department of Energy, 1995, pp.
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From page 28... ...
Given He large scale of He Hanford Site environmental remediation, it is prudent to review periodically total costs, total risks, and cumulative and indirect environmental impacts for the entire Hanford Site environmental remediation, and for the TWRS program specifically, In a public process. UNCERTAINTIES IN TANK AND ENVIRONMENTAL CHARACTERIZATION An important component of a long-term commitment to remediating the s~ngle-shell tanks at He Hanford Site is an adequate understanding of the nature of the present contents in the tandcs and He extent to which the soil and ground water beneath the tank farms have been contaminated.
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From page 29... ...
More discoveries are possible as tariff and environmental characterization studies proceed, and it is unclear at this point what Implications Hey may have for He conduct of He remediation program. The committee understands Hat a first step in characterizing single-shell tank conditions under the new Hanford Tanks Initiative (U.S.
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From page 30... ...
Estimates of potential health effects, both short- and long-term, for each of the remediation alternatives are scattered throughout He DElS volumes, malting comparison difficult. Risks are frequently presented as individual health effect probabilities without reference to time frame or size
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From page 31... ...
lithe uncertainties must not only be stated, but should be used to determine the extent to which the collective dose can be used as a surrogate for risk When the combined uncertainties in the exposed population, e.g., size, those related to characteristics, exposure pathways and individual doses, result in a collective dose with a relative uncertainty of more than an order of magnitude, neither estimates of collective dose nor estimates of collective risk are adequate for malting decisions." (National Council on Radiation Protection and Measurements, 1995, p.
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From page 32... ...
The NCRP admonitions concem~ng the use of collective dose as a risk surrogate should be recognized In We risk projections. Moreover, all estimates of exposures that could lead to future adverse heath effects were calculated on an upper-bound basis In the DElS rawer Han on He basis of expected values.s In keeping with He NCRP guidance and to facilitate a more meaningfill comparison of alternatives, both the expected value and range of heady risk estimates, as well as He upper-bound values, should be provided when possible for each remediation alternative.
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From page 33... ...
The practice of maximizing risk by upper-bounding of Me parameters inevitably leads to biased decision malting when comparing alternatives. As noted in a recent report of the National Research Council: Organizations responsible for characterizing risks should plan to blend analysis wad deliberative processes Cat cIanfy Me concerns of interested and affected parties, help prevent avoidable errors, offer a balanced and nuanced understanding of Me state of knowledge, and ensure adequately broad participation for a given risk decision.
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From page 34... ...
, tanlc proximity, and ground water flow direction. The nventones from individual tank farms were combined to create the waste inventory for each source area (DEIS, p.
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From page 35... ...
107) In the DENS, estimates of risk based on upper-bound assumptions do not represent expected values or reflect changing conditions over We 10,000year period.6 For example, the I-~n-1 risk of latent cancer fatality given to a waste site intruder (DENS, Table S.7.4)
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From page 36... ...
The term "closure" refers to a legal determination by regulators that an acceptable technical job of remediation has been accomplished. As applied to He Hanford tanks, closure requires remediating the tank wastes, as well as the tanks, ancillary equipment, and contaminated soil and ground water.
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From page 37... ...
Discounting any dilution during Me waste slurrying process, retrieval of We s~ngle-shell tank wastes could result In Me release of an additional I.7 million Ci of radioactivity to the surrounding soil, an amount on the same order of magnitude as the I.4 million Ci already estimated to have been released or leaked to the soil in Me 200 Areas. This leakage is explicitly excluded from Me scope of the DElS (p.
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From page 38... ...
Basing heads and environmental risk estimates solely on on-site source terms results In inconsistencies and gives an inappropriate basis for comparing various remediation alternatives. In other environmental Impact statements DOE has prepared comparative analyses of risks for alternatives involving waste disposal on and off site, including transportation risks Such a comparison need not require elaborate analysis; for example, risks Tom final repositories could be assumed to equal Me risk targets set in the EPA regulations.
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From page 39... ...
The numerous commitments that have been made in He Tri-Party Agreement to specific timetables for elements of He cleanup have rendered coordination of environmental documentation for the Hanford Site difficult, a problem exemplified by He limited discussion in the DElS of land use consequences of TWOS cleanup alternatives. CAPSULES AND MISCELLANEOUS TANKS There is little substantive discussion in the DEIS of the management and disposal of the cesium and strontium capsules and of the miscellaneous underground storage tarps.
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From page 40... ...
Additionally, the large number and wide distribution of the miscellaneous underground storage tanks make a more complete discussion of Heir management necessary. Cesium and Strontium Capsules Although the DElS describes the capsules and discusses their treatment and disposal, it is not clear that adequate attention has been given to the changes in chemical and isotopic composition that wall occur over time.
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From page 42... ...
hazard from He i37Cs or ] 35Cs in the capsules was considered charactenz~ng the Impacts of cesium capsule management alternatives.
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From page 43... ...
In approximately 830 years the concentration of 90Sr in the capsules would be less Man the low-level waste Class A level of 0.04 Ci/m3. Miscellaneous Underground Storage Tanks There is too little discussion of the miscellaneous underground storage tanks In Me DElS for a mearungfu} analysis of Weir proposed treatment and management and an evaluation of the adequacy of the alternatives In this application.
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