silo 3 - U.S. Department of Energy

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Assumptions:
E N 0 I N E E R I N ai.
PageNoA o f 3
35H19605
The joint-frequency distribution of wind speed and atmospheric stability as a function of 16 directions
contained in Feasibility Study Report for Operable Unit 2, Vo1.4, Appendix D, Femald Environmental
Management Project, March 1995, (Ref. 1) is indicative of average climatic conditions in the vicinity of
Silos 1 and 2 (Attachment A).
Stack height and outlet diameter of 125 ft and 27 in., respectively (Ref. 2).
Stack discharge rate of 13,900 ft3/min at 100°F during pneumatic waste removal in Phase 1. Stack
discharge rate of 12,700 ft3/min at 100 O F during mechanical waste removal in Phase 2 (Ref. 3). The
exhaust temperature ranges from 86°F in the winter to 106°F in the summer. The increase in exhaust
temperature relative to ambient temperature is due to heating from the fans (Ref. 4). Since a momentum
release is assumed in the calculations, the temperature-of theexhausted air is not an input parameter.
1000 m atmospheric mixing heighfflid
Estimates of air flow rates and radioactive particulate and radon concentrations in the stack discharge
provided by Hazard Category Calculations for Silo 3, 40430-RP-0006 (Ref. 5) and Process Flow
Diagram, Material Balance Table, Drawing 94X-3900-F-01428, Sheet F-0001, Rev. 0. (Ref. 3)
Standard exposure, radon equilibrium fractions, and default 'assumptions and dose conversion factors of
CAP88-PC for the evaluation of dose to a public receptor. Dose to workers is not evaluated in these
calculations.
Receptor assumed to spend 100% outdoors at the exposure location, 0% indoor at the exposure location
and 0% away from the exposure location. (Note: The maximum dose consequence to workers from
Silo 3 stack emissions would be lower than that to a member of the public since the maximum
atmospheric concentrations occur off-site. In addition, the worker occupancy will be lower.)
Conservative doses Lorn the exposure to radon progeny are calculated using an outdoor dose
conversion factor for Rn progeny of 570 mremhrorking level month, where a working level month is
defined as the product of the working level and the exposure duration (hrs) divided by 170 hrs (Ref 6).
This dose factor was obtained from ResRad (Ref .6)
Approximately 35 percent of the radon generated in the solid matrix material is free to emanate from the
solid into the waste pore space based on measured values (Ref.7).
The density of the Silo 3 waste is 50 lW3.