Scope. Chapter 4 presents the numerical screening and evaluation guidelines used in this
standard to determine at what stage in the approach the analysis of aircraft crash is sufficient.
This appendix presents the basis for the selection of these guidelines.
Exposure Screening Guidelines. Protecting the health and safety of the public is a
primary concern when considering the risk from releases of hazardous material resulting
from aircraft crash. This standard establishes three screening criteria for determining
whether a particular facility poses a potential threat to the public. These criteria set
exposure levels below which there are unlikely to be any significant health effects, even
to the maximally exposed individual in the offsite population. Each of these criteria is
listed below, along with the basis for its selection. Note that the criteria reflect a
consistent approach toward the selection of radiological and chemical exposure
guidelines, as opposed to an attempt to provide directly comparable guidelines. It would
be ideal if there were total consistency between the guidelines for radioactive exposures
and chemical exposures. However, given that chemicals act in different ways upon the
human body, and given that regulation of hazardous chemicals and radioactive materials
has historically never sought consistency (and given the desire to make as much use as
possible of already established regulatory precedents), it is too much to expect that total
consistency could be achieved here.
A.1.1 Exposure Screening Guidelines for Exposures Evaluated at the Site Boundary.
Radiological exposure - 25 rem (0.25 sievert [Sv]) committed effective
dose equivalent (CEDE).
Basis: First, note the distinction between committed effective dose
equivalent (CEDE) and total effective dose equivalent (TEDE). The
former is the accumulated dose over 50 years following inhalation or
ingestion of radionuclides. The latter includes, in addition, the dose
resulting from external irradiation.
A TEDE of 25 rem (0.25 Sv) at the site boundary has precedent as a
siting criterion, referenced in DOE Order 6430.1A, General Design