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OCR for page 39
THE HANFORD ENVIRONMENTAL DOSE RECONSTRUCTION PROJECT: A REVIEW OF FOUR DOCUMENTS APPENDIX: SPECIFIC COMMENTS ON HEDR DOCUMENTS PNWD 1983: HEDR Modeling Approach This is a useful summary of the modeling approach to the three environmental-transport pathways: air, surface water, and groundwater. It correctly recommends concentrating on the earlier periods of Hanford operations, when larger quantities of effluent were released. However, the committee makes the following observations: Page 5: There should be more detailed justification of the plans not to use any data for 1972-1992. Granted that the doses are much smaller than in the earlier years, total exclusion should not be decided on until the estimates are made. If “surrogate data” from the 1980s can be used to estimate earlier releases, as has been done, then it is hard to ignore the later releases without further evaluation. Pages 5 and 6: It is stated that “the HEDR Project has evidence that the necessary daily records no longer exist to allow detailed daily reconstruction for the period beginning 1950 through about 1953.” The nature of the missing data, the “evidence” for this assertion, and what is available for this period are not clear. The possible use of “surrogate data” from the 1980s and the Phase 1 calculations, which have been shown to be faulty, is of concern to the committee. It is not clear what “long-term monthly averages” means. Page 6: There seems to be some question about the need for a very high degree of resolution, e.g., a daily determination of soil, animal, and vegetation concentrations (paragraph 2.4) and a very fine grid. Agricultural produce and wild animals enter the food chain only at a few regional locations, and both consumption and concentration would not be expected to change rapidly, even after unusually large releases.
OCR for page 40
THE HANFORD ENVIRONMENTAL DOSE RECONSTRUCTION PROJECT: A REVIEW OF FOUR DOCUMENTS Page 7: For “selected individual releases calculations may be done if warranted. ” Under what circumstances would that occur? What criteria indicate a need for such calculations? Page 7: Beyond 1972, “doses will be done with reference to Hanford Site Annual Reports. ” Have the sources and accuracy of the annual reports been evaluated? This should be addressed if for no other reason than to ensure public acceptance of the reconstruction. Page 14: There is no indication that the models are to be validated by comparison with measured values of soil, food, and milk concentrations. In the absence of a correlation between measured and model-predicted values, use of increasingly sophisticated models would be futile. Each task group should identify gaps in the information with regard to its particular source terms at an early stage and indicate how it is proposed to bridge these gaps. Although it is important, for completeness, to review all potential pathways, development of models for unusual pathways, such as dermal absorption of iodine (page 14), can be justified only if published reports make this a believable scenario. Page 15: Clearly, the level of effort needed to model the river pathways is not yet determined. This seems to be of particular concern to some of the American Indian tribes, so the committee is concerned about the uncertainty. At the public meeting in Richland, a high level of public concern was raised for this particular pathway. Even if the contribution to dose from this pathway is relatively low, it should be established clearly and in detail. Page A.3: The exclusion of migrant farm workers from consideration (item 13) might be contentious, although it is recognized that it will be hard to collect reliable relevant data. Migrant farm laborers should probably be handled similarly as other short-term residents.
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