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Management of Commercially Generated Radioactive Waste - U.S. ...

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93<br />

CONSEQUENCE ANALYSIS<br />

about 1,000 years and that no significant release is expected for one million years. This<br />

is in apparent contradiction to results given in TM-36/21 (pp. xiv, 8.5 and 8.6). What is<br />

the expected rate <strong>of</strong> corrosion <strong>of</strong> the canister and the sleeve in salt brine or in fresh<br />

water? What are the values (or ranges) <strong>of</strong> effective hydraulic conductivity, porosity,<br />

retardation factors and hydraulic gradients <strong>of</strong> the rock mass surround the repository that<br />

were used to obtain Tables I.1 to 1.12? (208-NRC)<br />

Response<br />

This was intended to be a parametric analysis and actual container life was not given.<br />

The commenter may have misunderstood the term "release". In some cases, no significant<br />

releases to the biosphere may occur for a million years.<br />

Draft Appendix I<br />

Issue<br />

This appendix is deficient. It is based on leaching <strong>of</strong> the entire repository by ground<br />

water, passage <strong>of</strong> nuclides through a rather freely flowing aquifer, and discharge into a<br />

large surface stream (10,000 cubic feet per second or 8.9 x 1012 liters per year). If we<br />

apply the generic density <strong>of</strong> population in terms <strong>of</strong> river flow from our forthcoming dose<br />

assessment report, which is 3.3 x 10 -7 person years per liter, the river is capable <strong>of</strong><br />

being a water supply for about three million people, a great many <strong>of</strong> whom would receive<br />

close to the maximum individual dose. (113-EPA)<br />

Response<br />

The R river in the reference environment supplies about two million people which is<br />

close to the three million as estimated above using a generic population density. The<br />

drinking pathway is the only pathway <strong>of</strong> exposure. In the dose distribution a large fraction<br />

<strong>of</strong> the down stream population might receive nearly that dose received by the maximum indivi-<br />

dual. In another groundwater scenario a ratio <strong>of</strong> 1/5 was determined between the maximum<br />

individual and the per capita dose.<br />

Draft Appendix I<br />

Issue<br />

An apparent conflict exists between the basic assumptions in the main text and<br />

Appendix I. The main text stated that "....disposal in salt has been emphasized..."<br />

(p. 3.1). However, the assumptions made in Appendix I (p. 1.9) for an earlier analysis<br />

(which was the basis <strong>of</strong> the current version <strong>of</strong> the Impact Statement) assumed that the repos-<br />

itory is in a non-salt media. Furthermore, some <strong>of</strong> the details <strong>of</strong> the model should be<br />

briefly summarized in the appendix. The statement "Detailed descriptions <strong>of</strong> these models

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