HPAVC/HPAVC CD-ROM.iso/HOMEWORK.ZIP/NUKE-NY.TXT

Text File | 1998-07-25 | 18KB | 232 lines

Date sent:        Tue, 23 Apr 1996 14:21:14 +1100

Nuclear waste disposal is the way of transporting nuclear  high-level  waste and fuel
rods from a nuclear power production facility and safely isolating them from the environment
as much as possible. Many theories abound as how to achieve this; yet as of today, there is
no permanent storage facility in the United States licensed to take in this dangerous
byproduct-- even after 50 years of power production through nuclear fission.
     The first nuclear waste was produced by the military during the Manhattan Project in
     the
1940's.   The military undertook this project to produce the first nuclear weapons for use
during World War Two.
     During the beginning of the Cold War, the military continued to produce and stockpile
nuclear weapons, creating a huge amount of radioactive waste. By 1957, the first commercial
nuclear reactor for electricity production was finished.    Finally, in 1982, under strong
nuclear industry and public pressures, the US Congress passed a comprehensive group of laws.
These laws were collectively known as the Nuclear Waste Policy Act of 1982 [as amended], or
NWPA. The NWPA provided states with a limited veto to eliminate nuclear waste from being
placed in their state, and provided the same privilege to Native Americans on their
reservations.  Other provisions of the NWPA also set up the Nuclear Waste Fund that cost the
end consumer $.001 per kilowatt hour for those served by nuclear energy.  This fund was
supposed to provide the nuclear industry and government with enough money to build a
permanent disposal site.  The government also set up subsidies for nuclear power.  It also
authorized the Department of Energy (DOE) to conduct research for onsite-dry-storage
technology for isolating spent fuel. [This will be covered more later in the paper].  It
gave the DOE money to display and build prototypes for the above  technologies, and endorsed
a federal mid-range storage facility, the Monitored Retrievable Storage System (MRS) [this
too, will be covered later in the paper].
     The NWPA ordered the DOE to take title and responsibility for all nuclear waste by or
on January 1, 1998. This date is rapidly approaching today, but the government is still
without a place to put the waste.  It seems like the environment is being assigned a lower
priority to solve an urgent waste disposal problem that should have been addressed 40 years
ago. Scott Saleska, who has done lots of research into the disposal crisis, said  Finally,
the NWPA did not even address the fundamental issue that still remains today -- the
advisability of continuing to use nuclear energy in the absence of a proven method for the
permanent disposal of high-level nuclear waste.
     Today, the largest problem is finding an acceptable way of storing nuclear waste over
     the
long term since most nuclear wastes have a radioactive life of over 100,000 years a period
longer than all of recorded history.  The four main categories of waste disposal are:
     a.   Land disposal
     b.   sub-seabed disposal
     c.   ice-sheet disposal
     d.   space disposal
      The most research has been put into what is called  deep geologic disposal .  This
      places
nuclear waste into a repository below ground, usually in an isolated area with a solid rock
formation, this is the primary form of land disposal.  The waste is placed at a depth of
600+ meters, about 1/3 of a mile.  This was the first option seriously studied by both
scientists and the nuclear industry, and is still the most actively pursued option in the
U.S. today.  The most important issue is the  host rock , which is the type of rock
surrounding the repository site.  The most preferred are salt beds, which in 1957 was
endorsed by the National Academy of Sciences as the  most promising  rock form.  The good
points are that salt is virtually waterproof, so water will not seep down into the
groundwater travelling beneath the waste  Also,  most fractures in the salt are
self-sealing, stopping radiation from simply floating up to the surface through faults or
pores in rock.  Also, after a short period, the salt will move and seal the waste into a
solid mass of salt.  The current site being debated for deep-geologic disposal is a site at
Yucca Mountain, Nevada.  Rock surrounding the site is volcanic tuff, a type of igneous rock
formed by a volcanic eruption. Volcanic Tuff is a very stable type of rock, but water can
penetrate through it even down to the proposed waste site, 2,500 feet below ground.  Also,
near this site is an operating gold mine only 6 miles away.  The use of this site, then, is
undesirable, because future habitants of earth mining in these mountains could uncover the
waste we buried there.  Nevada's State Legislature also passed two resolutions outlawing
disposal of radioactive wastes at this site. Understandably, no one wants waste in their
city, state or region.  Therefore, the construction and use of a site within the borders of
the United States is difficult to achieve.
     However, in some isolated places, it has been possible to select a site, as with the
     WIPP
(Waste Isolation Pilot Plant) a repository for military produced nuclear wastes.  It is
located in southeast New Mexico s Eddy County.  If finished and used, it will be the
nation's first geologic storage facility for the sole purpose of isolating forms of nuclear
high-level waste.  It is located 650 meters below the desert surface, in a thick salt bed.
The facility up to this point has cost $700 million to build.  If completed, it will hold
1,100,000 fifty-five-gallon drums filled with nuclear waste, a total of 6,500,000 cubic feet
of waste.  The site occupies 100 underground acres for storage, and 12 underground acres for
research and development.  The site, however, has a long list of problems.  There are
pressurized water pockets below the surface, and if one of them ruptures, it could saturate
the waste and possibly launch it straight back up to the surface.  Also, water already has
leaked into the site, and walls that surround the site have been cracking and allowing salt
to creep in which lock the barrels into salt masses too quickly.  Documentation and
construction permits are missing, and the construction quality was extremely poor.  It seems
as if speed was more important than safety in the creation of this facility, because it was
put on such an urgent timetable.
     Another alternative for disposal included the addition of Chemical Resynthesis of the
waste which converts the waste into a chemical that would be compatible with the host rock,
and insoluble to water.  It is currently just an idea, and would still require the waste to
be buried in a geologic repository.
     A totally different concept for land disposal is Very Deep Hole Disposal, where the
     waste
is put at the bottom of a hole 10-12 kilometers deep.  A total of 800-1200 holes would be
needed at each site.  There is a much smaller possibility that the waste will migrate to the
surface, and the heat inside Earth could cause the waste to be melted into the rock deep
underground. However, the depth and prohibitive number of holes would make this very
difficult to achieve.
     Another idea, Melted Rock Disposal, involves placing the high-level waste directly into
an underground rock cavity. Eventually enough heat will be created around the canister by
the heat from deep within the earth to melt all the rock surrounding the canister, and the
melted rock will trap the waste into an immovable rock cluster.
     One other concept for land disposal, Island Disposal, places the waste into a cavern
under an island, in the same manner as Deep Geologic Disposal, except that it is on an
island and not on the mainland.  The problem, however, is the danger of transporting the
waste over the sea, where a shipwreck could cause irreversible harm to the oceans. However,
this makes the waste less harmful to humans living on the mainland.
     Deep-Well Injection, the final plan for disposal on land, is where  waste in the form
     of
slurry, a watery mixture of insoluble matter is mixed with cement and clay and injected
between layers of rock at depths of up to 500 meters."  Used until 1983 by the DOE to
dispose 17,300 cubic meters of DOE and Military created low-level waste.
     Another place to put waste is the bottom of the ocean, in a method known as Sub-Seabed
Disposal.  In the most common way proposed of Sub-Seabed Disposal is where waste is placed
30 meters under clay on the seabed, most likely in the North Central Pacific, south of the
Aleutian Islands, or a similar site.  The wastes will be placed in fin-tailed, needle nosed
recepticals, and dragged across the sea floor. Clay will eventually re-seal itself over the
case. Other variations included using free-fall penetrators, dropped from sea-level, where
their momentum will plunge them beneath the seabed.  Also, holes could be drilled, with the
canisters lowered into these holes.   Sub-Seabed disposal has the advantages of the relative
long-term stability of the ocean bottom, as compared to the stability on land. The large
size of the ocean floor makes it ideal for disposal possibilities.  Ocean floors also
provide total  remoteness from human activities or major concentrations of natural
resources.  Also, it removes the need to resolve Federal/State disputes over where to put
the waste. However, it would require the support of many nations and international
organizations.  Also, an ocean transport facility, not currently available, would need to be
designed and produced.  Difficulty is also encountered in documenting the exact location of
where we deposited the waste for future generations. Potential for ecologic disruption of
the oceans exists if the canisters and clay could form balls of fluid mud or clay and rise
to the ocean floor.
     Up in Greenland and Antarctica another site for possible nuclear waste disposal exists
     in
the massive ice-sheets that cover the land and oceans.  The most popular method would be
meltdown, where each canister would be placed into a shallow hole, and the heat created
internally by the waste will cause the canister to sink down to the bedrock under the ice
sheet in approximately 5-10 years.  Also, the anchored method would attach each canister to
a 200-500 meter cable, which is anchored at the surface.  This way, the canister can be
retrieved for several hundred years until the whole system sinks, taking 30,000 years to
reach the bedrock.  There also could be a structure built at the surface, in a method called
Surface Storage, in which the waste would be stored inside the facility and can sit there
for hundreds of years before sinking.  The advantages of these methods would be that the
sites are almost totally remote from humans, and the conditions there will be approximately
the same for millions of years.  However, the long transport distances in moving the waste
and high cost and difficulty of working in these polar regions could remove this from
practical use.  The uncertainty of long-term ice/waste reactions is also still unknown.
     The final method of long-term storage is Space Disposal, in which the waste is attached
to a rocket, and sent into space, where it could be: 1.   Sent into the Sun 2.   Put into
orbit around the Earth or the Sun 3.   Sent out of the Solar System altogether
     The main advantage to this method is that the waste is permanently and totally removed
from the Earth, for today, tomorrow and future generations or inhabitants.  However, the
cost and risk of a launch accident have removed this from serious consideration, though the
amount of progress made recently into space research could possibly bring this back, as it
seems to represent the best possible way to remove the waste from the environment.
     Until a site is found for permanent disposal, a variety of methods for mid-term waste
disposal have been sought out, starting with the mid-range system proposed in the 1982 NWPA,
the MRS, or Monitored Retrievable Storage System.  The purpose of such a facility would be
to receive and prepare waste from a commercial reactor into temporary storage, before final
disposal in a geologic site.  Another clause in the NWPA said that no one MRS site could
hold more than 10,000 metric tons, and that it cannot be constructed until a permanent site
has been completed, so that the MRS site does not turn into a permanent storage facility.
     Until the completion of a permanent or even mid-term storage facility, the main site
     for
waste storage is at the nuclear plant itself. Many new technologies for waste disposal have
emerged from the need for these sites, including various Dry Casks, used to hold nuclear
waste and fuel rods. They are explained in the coming paragraphs. The Dry Casks offer the
advantages of not using water, so they cannot trigger a chain reaction among themselves, and
no low-level waste water is created.  They are self-contained, and there is little need for
maintenance.  There are no mechanical parts that could rust or break, as in many water based
temporary storage solutions.  It is not totally safe, but as I have found through this
research, nothing really is.
     The oldest and most common dry cask is the Metal Storage Casks. A Metal Storage Cask
looks like a casket or a safe and is made of lead or another dense metal. These casks were
first experimented with in 1984, as one of the first onsite repositories for nuclear wastes.
     Also gaining serious support, especially in West Germany, are the Dual Purpose Casks,
which are similar to metal, but offer the advantages of use in both storage and
transportation. They  potentially eliminate the handling operations needed to transfer the
irradiated fuel from storage to transportation casks.   They are not currently used in the
U.S..
     The Concrete Storage Casks, which are also similar to metal, have linings of metal
     inside
a highly reinforced concrete body to offer more resistance against corrosion or oxidation of
the metal. These are not currently used in the US.
     The Horizontal Concrete Modules, where  in this design, irradiated fuel is stored in
     large
stainless steel containers that are filled with gas and sealed inside a concrete module."
One plant is currently using this design, and three others are at various stages of
development. This may be the most useful and efficient method of waste disposal.
     Modular Concrete Vaults: An array of vertical tubes in which intact fuel rods are
     stored.
After the tubes are filled, the tubes are surrounded and encased in concrete.  They have
been used in Great Britain for 17 years, but have not been set up into the U.S. as of today.
     Current Plants using Dry Casks for storing their waste include:
1.   Virginia Power Company, with Metal Casks at its Surry Nuclear Plant
2.   Carolina Power and Light, with Horizontal Concrete Modules at its H.B.Robinson Plant
     near Hartsville, SC
3.   Developmental Stages at: Duke s Power s Oconee Plant near Seneca, SC
4.   Developmental Stages at: Baltimore G+E s Calvert s Cliffs facility near Annapolis, MD
     However, by far the most popular method of isolating waste for the short-term, onsite
     is
the Water Pool Method, where the rods are dropped into large pools of water, which is an
excellent barrier to nuclear radiation, to keep emission levels low. However, this method is
unsafe, the water can possibly ignite a chain reaction and low-level waste water is created.
     The effects of radiation on humans are well known, and can be very harmful to all
aspects of the body.  The average human receives 360 millirems/year or one per day.  An
average chest x-ray inflicts .03 rads of radiation on the human body, and just living a
normal life inflicts .1 rad a year. A rad is a unit measuring the amount of radiation
absorbed by the body. Death occurs when the body absorbs over 300-600 rads, and the nuclear
worker limit for radiation absorbed is five rads/year.  Most nuclear workers receive about
.25 rads/year.
     Obviously, there are many possibilities on how to safely remove nuclear waste from the
environment, and all have advantages and disadvantages, and while it is not up to me to play
God with such a serious problem, the most logical plan of action is to store the waste
onsite in Horizontal Concrete Modules, then have the wastes processed at MRS sites, then
sent off into space, where it can be totally separated from the environment. However,
someday, very soon, we must make some serious decisions as how to receive, process, and
store our nuclear wastes. However,  until we decide what to do with this long-lasting
poison, maybe the continuation of producing  nuclear energy isn't such a good idea, after
all.  America needs an enforceable, affordable and efficient method of storing this waste,
and time is running out.  It's time to make something happen.



Name : Nuclear.TXT
 Uploader: John Doe
  EMail: [e-mail]
  Language: English
  Subject: Physics
  Title: Nuclear Waste.
  Grade: 91%
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  Country: New York
  Comments:
  Where I got Evil House of Cheat Address: my teacher