Exposure Pathways

DOE-STD-1027-92

ATTACHMENT 1

The NRC then stated that "for all materials of greatest interest for fuel cycle and other

radioactive material licensees, the dose from the inhalation pathway H I will dominate the

dose" and dismissed the other contributors. Simplifying assumptions for Gaussian

dispersion and particle deposition were then used to calculate inhalation doses.

In modifying the NRC results, DOE has restated the equation above as

(1 rem)/(RF*SA*X/Q*(CEDE*RR + CSDE))

where

Quantity of material used as threshold (grams)

Airborne release fraction of material averaged over an entire facility

RF =

(unitless)

Specific activity of radionuclide released (Ci/gm)

SA=

Expression accounting for dilution of release at a point under given

X/Q=

meteorological conditions (sec/m 3)

CEDE= Committed effective dose equivalent for a given radionuclide

(rem/Ci)

RR=

Respiration rate, which is assumed equal to the standard value

used for an active man (3.5 E-4 m3/sec)

CSDE= Cloud shine dose equivalent (rem*m3/Ci*sec)

Specific modifications to forms of the equation are discussed in distinct sections below.

Exposure Pathways

As can be seen from the modified equation, DOE concurred with the NRC's dismissal of the

ground contamination exposure pathway. In general, DOE concurred with the dismissal of

cloudshine exposure as well because this path accounted for, on average, slightly less than

2% of dose for all radionuclides but the noble gases. Although, for the types of material that

DOE handles, it is expected that the values for noble gases will be included in the mixed

fission product threshold, DOE decided to retain this exposure pathway in the calculation for

Meteorological Conditions

DOE chose to modify the NRC meteorological assumptions used for hazard categorization

purposes. NRC used F stability at 1 m/sec meteorological conditions whereas DOE used D

stability at 4.5 m/sec for the following reasons:

A-6