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

5.91
salt. If an adequate source of water is available, nine wells each operating at about
23 /sec would be sufficient.
The actual solution chemistry of leached radionuclides moving into the salt brine is
not known. An assumption of the scenario is that radionuclides leached from spent fuel mix
completely with the salt brine and are carried to the surface. Although it may take 1/2 to
1-1/2 years to bring a brine well to production, in the scenario, the brine well produces
immediately and continuously for 50 years, at the end of which the entire quantity of salt
surrounding the waste would have been mined out. Water flow would follow a course of least
resistance and would follow the previously mined cavern boundaries where possible; this
maximizes the consequences.
Details of the calculations for leaching of radionuclides in spent fuel and in repro-
cessing waste with the disposed salt may be found in Sections 4.4.and 9.3, respectively, of
DOE/ET-0029.
If 3% of the 2.4 million metric tons of salt mined per year is used for human consump-
tion, then about 72,000 metric tons would be used for that purpose. If a person consumed
1800 g/yr then 72,000 metric tons of salt would provide for about 40 million persons. For
purposes of this analysis the exposed population consists of 40 million persons.
Although daily monitoring controls on the salt would bring attention to the presence
of contaminated salt, the possible failure of such monitoring was recognized. The pro-
ducers' quality assurance laboratory may not recognize the failure for a week. That fail-
ing, it might take as much as a year before a consumer discovered the contamination. On
this pessimistic series of circumstances the conclusion was that a reasonable upper bound
on waste entering the food trade would be that in salt produced in one year. Therefore, the
consequences of this accident in terms of radiation dose to an exposed population of 40 mil-
lion persons from ingestion of contaminated salt for one year were calculated. The quanti-
ties of radionuclides which contributed significantly to whole-body dose and the doses
are listed in Table 5.5.11.
TABLE 5.5.11. Amounts of Radionuclides (Ci) and 70-Year Whole-Body Dose
(in rems to an individual) Resulting from Ingestion of 1800 g of
Contaminated Salt 1000 years after Repository Closure
2 3 9 Pu 1.5 x 10 - 6
- 6
240Pu 2.2 x 10
- 6
241Am 4.5 x 10
2 4 3 Am 6.6 x 10 - 8
Curies rems
Spent Fuel Reprocessing Spent Fuel Reprocessing
Repository Waste Repository Repository Waste Repository
2.2 x 10
- 8
- 7
1.2 x 10
- 6
1.3 x 10
- 7
2.4 x 10
- 2
3.6 x 10
5.3 x 10- 2
- 4
5.5 x 10
- 3
3.1 x 10
- 2
3.0 x 10-1 8.6 x 10
4.0 x 10 1.5 x 10
Total 3.9 x 10-1 1.0 x 10-1
The 70-yr whole-body dose commitment to the exposed population of 40 million persons
would amount to 1.6 x 107 man-rem for such an event occurring in a spent fuel repository and
to 4.0 x 106 man-rem from a similar event at a repository for reprocessing wastes. These