[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Technical and Economic Feasibility for Extracting Fissile Fuel for NuclearReactors from Coal Fly Ash
I've had some interesting discussions with Alex Gabbard concerning this
subject. Alex has given me permission to post his remarks that provide
additional details to his original article (see below).
It appears from his comments that the one major roadblock to using coal fly
ash waste as a resource is the cost of handling and disposing of the
leftover radioactive waste after an enrichment process. The handling and
storage of radioactive waste is routine business for us and we do it well.
However, the cost of disposal is the real barrier. The current regs only
identify natural thorium and uranium as radioactive material when they are
"technologically enhanced". My understanding of the current interpretation
of the regs is that burning coal does not technologically enhance the
natural products but the process of extracting these and other elements
does technologically enhance the resulting waste containing natural
products. And this technologically waste containing natural products
requires burial as radwaste. Disposal seems the only real barrier to
taking existing waste and turning it into useful products in great demand.
We should be able to come up with solutions to overcome this barrier.
Anyone have any suggestions?
John M. Sukosky, CHP
Dominion
Surry Power Station
(757)-365-2594 (Tieline: 8-798-2594)
----- Forwarded by John Sukosky/NUC/VANCPOWER on 12/05/03 12:20 PM -----
Alex Gabbard
<gabbardwa@ornl.g To: John_Sukosky@dom.com
ov> cc:
Subject: Re: Technical and Economic Feasibility for Extracting Fissile Fuel for
12/04/03 01:33 PM Nuclear Reactors from Coal Fly Ash
Hello John,
Many references exist for additional information on nuclear aspects of
coal. Some primary references are as follows:
1. Lyon, W. S. et al: Nuclear Activation Techniques in the Life Sciences,
IAEA, 1978
2. Valkovic, V., Trace Elements in Coal, Vol 1, CRC, 1983
3. Facer, J. F. Uranium in Coal, Rep. GJBX-56(79), USDOE, Grand Junction
office, Colorado, May 1979
4. Background Information Document (Integrated Risk Assessment); Final
Ruling for Radionuclides, USEPA Report EPA 520/1-84-002=2 Vol II, 1984
5. Coal Fired Power Plant Trace element Study, Vol 1, A Three Station
Comparison, US Dept of Commerce, PB-257293, Sept 1975
6. Wilder, R. F. et al, Recovery of Metal Oxides from Fly Ash Including Ash
Benefaction Products, Electric Power Research Institute, CS-4384, Vols 1-3,
1986
Reference 6 is an extensive study concluding that metal extraction using
1986 technology was not only economical then but a potentially significant
additional income source from power production.
Coal is, I believe, an untapped resource for a multitude of valuable
elements. For example, at least 73 elements have been identified in coal
(1), but little use is made of its ingredients other than bulk fly ash for
building materials such concrete filler. Of the elements identified in
coal, combustion throughput each year in metals alone constitutes billions
of dollars of potentially useful resources.
To calculate throughput, a coal fired plant of 1 GWe capacity requires 4-5
million metric tons of coal each year. With components expressed in parts
per million (ppm), calculating element throughput becomes easy as related
to such a plant. Determining throughput for any plant can then be
calculated as a matter of comparative capacity.
Looking at just a few metals, elemental analysis as reported in several
references (2) provides the following: Al = 26,400 ppm; Cr = 29.54; Cu =
20.38; Fe = 15,100; Hg = 0.335; Mg = 3,419; Mn = 39.5; Ni = 17.9; Pb =
10.8; Th = 4.58; Ti = 1,242; U = 2.08; V = 45.49; Zn = 26.42; Zr = 30.
Thus, calculating annual throughput of these metals is simple: (4 million
metric tons) x (concentration in ppm) = throughput in metric tons per 1 GWe
plant. Consequently, annual throughput of elements in metric tons: Al =
105,600; Cr = 118; Cu = 81; Fe = 60,400; Hg = 1.3; Mg = 13,676; Mn = 158;
Ni = 72; Pb = 43; Th = 18.3; Ti = 4,968; U = 8.3; V = 182; Zn = 106; Zr =
120.
Since the US consumes coal annually at a rate equivalent to about 250
plants of GWe capacity, multiplying these tonnages times 250 arrives at
nationwide throughput of these metals. Using metal spot market prices of
1995, just these 15 metals comprise a worth of about $100 B/yr wasted in
the US alone. Worldwide coal usage is greater than 5x US usage, thus at
least a factor of five higher in value.
Using the petrochemical industry as a model, which did not exist a hundred
years ago, one can project the potential value of coal as a resource in the
coming century. However, "folklore" continues to say, "if it were
economical, we would be doing it." In EPRI's study of 1986 (6), the
conclusion based on currently available technology was that extraction of
metals for sale to available markets would be profitable. Yet, no such
undertaking has resulted for a number of reasons. The radioactivity in the
U and Th components in coal are instructive in understanding why.
Since these elements are radioactive, and since their age in coal is such
that each daughter is populated in secular equilibrium, a total of 39
radioisotopes from the parents U-238, U-235 and Th-232 (+ K-40 naturally
occurring in potassium in coal, K = 4,550 ppm) yields 40 radioisotopes in
coal. Secular equilibrium allows calculating radioactivity and
radiotoxicity resulting in about 60 Ci/yr of activity and greater than 100
gm Pu-239 equivalent (Hazard Equivalent Plutonium) for each 1 GWe/yr. The
quantity of U + Th = 4(6.66 ppm) = 26.6 metric ton largely collected in ash
ponds indicates that as coal is burned, its volume decreases to about 1/10
the original volume. Consequently, the rad-stuff in the ash is enrichened
proportionately, to about U = 11 ppm and Th = 45 ppm. Analyses of raw fly
ash has shown radioactivity to be several times background.
As a result of further depletion of coal ash of valuable elements such as
metal oxides, the total volume of remaining ash declines while
concentrating the U + Th families. Ultimately, when all other ingredients
are removed, handling metric tons of residual U + Th and associated
radioactivity will drive the cost of handling combustion wastes into the
prohibitive range because of regulatory requirements on handling, storing,
shipping, etc nuclear material. Whether or not a market exists for such
large volumes of radiological material is questionable, and even if
collected uranium oxide is sold at ~$2000/lb, the non-marketable rad
species will likely incur significant long term cost.
Thus, no one is interested in tapping coal of its resources knowing the
regulatory climate associated with rads. Meanwhile, coal combustion waste
streams do contain these materials that are constantly and freely exhausted
to the biosphere, with EPA's blessing (4,5).
Regarding U-235: natural uranium, as found in coal, contains about 0.71%
U-235. Technologies for separation of U-235 are well known but tightly
controlled. They are also costly, time consuming and difficult processes.
Hope this is helpful.
Alex Gabbard
Oak Ridge National Laboratory
Metals and Ceramics Division
P.O. Box 2008
Oak Ridge, TN 37831-6090
************************************************************************
You are currently subscribed to the Radsafe mailing list. To
unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu Put the
text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,
with no subject line. You can view the Radsafe archives at
http://www.vanderbilt.edu/radsafe/