Dose Reconstruction for the Fernald Facility A Review of Task 4 (1994) / Chapter Skim
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II. STATUS OF SOURCE TERM
II. STATUS OF SOURCE TERM
Pages 12-18
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From page 12... ...
In its evaluation, the committee used the < 2.5 ,um and > 20 Em sizes as presented. The data were tested and found to be lognormally distributed; the geometric means and standard deviations calculated by the committee are shown in Table 1.
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From page 13... ...
Although particle-size data collected by impaction instruments tends to fall off at both the low and high ends of the particle-size scale, this fall off does not significantly affect the observed particle-size distribution, which appears to be lognormally distributed. Because of this lognormality, the geometric mean and standard deviation are readily calculated for use in estimations of deposition with standard national and international lung models that assume a lognormal distribution.
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From page 14... ...
Table D-1 Stack G4-2 8.7 1.85 Stack G4-5 6.6 2.20 Stack G4-12 7.9 1.71 Stack G4-14 8.3 1.97 Stack G5-249 6.5 2.06 Stack G5-250 7.7 2.05 Table D-2 Stack G4-2 7.5 1.70 Stack G4-5 5.8 2.05 Stack G4-12 9.2 1.67 Stack G4-14 12.5 1.55 Stack G5-249 9.5 1.74 Stack G5-250 13.3 1.53 Stack G5-253 8.1 1.88 Table D-3 Stack G5-254 5.5 1.88 Stack G5-256 5.4 1.96 Stack G5-261 6.7 1.82 Table D-4 Stack G5-254 7.0 2.05 Stack G5-256 7.9 1.74 Stack G5-260 6.9 i.84 Stack G5-261 10.1 1.79 14 Geometric Standard Deviation
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From page 15... ...
The model tends to underestimate uranium depositions as previously predicted with gummed-film measurements, primarily because of assumptions about removal of large particles by deposition and therefore overestimates the uranium concentrations in air at distances from the facility. Uncertainties in meteorologic data, about the source term, and in air measurements themselves also contribute.
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From page 16... ...
At the very least, the authors should discuss reasons why their report's source term is 100 times the results of Stevenson and Hardy. Soil measurements might have little bearing on validation of the airborne model, particularly if soil was disturbed, and they could be of questionable value if wake effects predominated.
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From page 17... ...
There also will be an appreciable uncertainty associated with estimates of early episodic releases, and it will be important to conduct a sensitivity analysis to eliminate minor, but highly uncertain, contributions to the total dose. Although the techniques of dealing with data distributions for the Cincinnati climate were most useful and helpful to the approach to determining dispersion input parameters, many of the assumed distributions seem arbitrary.
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From page 18... ...
RAC appears to have used monitoring measurements that deal only with radon seepage after the cracks in the dome were sealed. These might have little bearing on previous release conditions and their radon progeny equilibrium.
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