Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 351
E
Origin of Radioactivity in
Fuel-Cycle Facilities
Fuel-cycle facilities are involved in the extraction and processing of
uranium to produce fuel for nuclear reactors. Consequently, the most im-
portant radioactive effluent releases from these facilities involve uranium
and its decay products (Table E.1).
Uranium and its decay products are present in equilibrium at mining
and milling facilities (Figure E.1). The uranium decay products are removed
during the milling process1 and disposed of onsite as mill tailings (Fig-
ure E.2), which are potential sources of radioactive particulate and radon
gas effluent releases from these facilities.
Other radioactive isotopes are sometimes present in effluent releases
from enrichment and fuel fabrication facilities, usually at trace levels. These
include cesium-137, technetium-99, as well as a number of actinide iso-
topes, most notably uranium-236, neptunium-237, and plutonium-239/240.
These isotopes are produced by fission and neutron-capture reactions (these
reactions are described in Appendix D). Their presence in an effluent release
indicates that the facility has processed uranium that was previously irradi-
ated in a nuclear reactor.2
1 However, the decay products “grow back” into the uranium with time, especially those
decay products near the top of the uranium decay chains, which have short half-lives (see
Figure E.2).
2 For example, recycled uranium (i.e., uranium obtained from reprocessing spent nuclear
fuel) was enriched at the Paducah Gaseous Diffusion Plant between 1953 and 1975. This plant
is still reporting releases of radioactive effluents from this recycled uranium.
351
OCR for page 352
352 APPENDIX E
TABLE E.1 Typical Effluent Releases from Fuel-Cycle Facilities
Facility Type Typical Radioactive Effluents
Mining (in situ leaching) Uranium, radon, and progeny
Milling Uranium, radon, and progeny
Conversion Uranium, radium-226, thorium-230
Enrichment Natural uranium, uranium-235, thorium-230, technetium-99,
neptunium-237, plutonium-239, 240
Fuel Fabrication Uranium-234, 235, 236, 238
FIGURE E.1 Schematic illustration of the uranium-235, thorium-232, and ura-
Figure E.1.eps
nium-238 decay chains showing decay modes (i.e., alpha or beta decay), half-lives,
and progeny. SOURCE: U.S. Geological Survey, http://gulfsci.usgs.gov/tampabay/
bitmap
data/2_biogeochem/images/decaychain.gif.
OCR for page 353
353
APPENDIX E
FIGURE E.2 Aerial view of the White Mesa Uranium Mill near Blanding, Utah. The
Figure E.2.eps
mill facilities can be seen in the upper right quadrant of the photo. The filled and
active mill tailings ponds cells occupy bitmap remainder of the photo. SOURCE:
most of the
Elise A. Striz (USNRC) presentation at the Atlanta committee meeting.
OCR for page 354
