[TheForge] Hellooooooo!

[Todd Rich]

On Mon, 8 May 2006, wmullett at bright.net wrote:

> Medical waste is NOT the problem.
>
> "Reactor waste remains hazardous for a very long time. Most medical waste from treatment and diagnosis is hazardous for a very short time. Research and industrial waste can contain small amounts of some long-lived radioactive materials.
>
> Among the radioactive elements commonly found in nuclear reactor 
> "low-level" waste are: Tritium, with a half-life of 12 years and a 
> hazardous life of 120-240 years;

However, Tritium is valuable in and of itself, so signifigant effort is 
made to seperate it out.

> Iodine-131, half-life of 8 days, 
> hazardous life of 80-160 days;

Very dangerous, and very short lived. Unless there is an active nuclear 
accident going on (Chernobyl), you won't find it in the envoronment.

> Strontium-90, half life of 28 years, 
> hazardous life of 280-560 years;

Fairly dangerous, mainly due to the fact it decays into Yttrium-90, which 
has a half life of 64 hours, and a specific activity of 550,000 Curies per 
gram as opposed to Strontium-90s 140 Curies per gram.

> Nickel-59, half life of 76,000 years, 
> hazardous life of 760,000-1,520,000 years,

From: http://www.ead.anl.gov/pub/doc/nickel.pdf

]The long half-life of nickel-59 (with its subsequent low specific 
]activity) combined with its low decay energy limits the radioactive 
]hazards associated with this isotope.

Are you sure you didn't mean nickel-63? It occurs in higher 
concentrations, has a shorter half life and a much higher specific 
activity.

>and Iodine-129, half-life of 
> sixteen million years, hazardous life of160-320 million years.
>
From: http://www.ead.anl.gov/pub/doc/iodine.pdf

]A small amount of radioactive iodine-129 is produced naturally in the 
]upper atmosphere by the interaction of high energy particles with xenon. 
]Iodine volatilizes at ambient temperatures into a pretty blue-violet gas 
]with an irritating odor. Iodine exhibits some metal like properties and 
]is only slightly soluble in water. It occurs in nature as iodide ions, 
]and it is in this form that it is taken into our bodies.
]Of the fourteen major radioactive isotopes of iodine, only iodine-129 has 
]a half-life sufficiently long to warrant concern for Department of Energy 
](DOE) environmental management sites such as Hanford. (Isotopes are 
]different forms of an element that have the same number of protons in
]the nucleus but a different number of neutrons.) Iodine-129 decays by 
]emitting a beta particle with a half-life of about 16 million years; the
]half-lives of all other iodine radionuclides are less than 60 days. The 
]very long half-life of iodine-129 (with its subsequent low specific
]activity) combined with the low energy of its beta particle and minimal 
]gamma radiation limit the hazards of this radionuclide.

Btw, hazardous life is really a bit of a misnomer here.  If the material 
isn't that hazardous to begin with, stating the amount of time it takes to 
go through enough half lives to almost completely decay doesn't mean much.

A good rule of thumb for radionuclides is the shorter the half life, the 
hotter the isotope, and the more dangerous while it is decaying.

> By contrast, common medical waste elements include Technetium-99m, with 
> a half-life of 6 hours and a hazardous life of 2.5-5 days; Galium-67, 
> half-life of 78 hours and hazardous life of 1-2 months; and Iodine-131, 
> with its half-life of 8 days and hazardous life of 80-160 days.
>
> The vast majority of medical waste is hazardous for less than 8 months. 
> Yet, it is in the same category as reactor waste that will be hazardous 
> for hundreds of thousands to millions of years.
>
> Clearly, the definition of "low-level radioactive waste" must be 
> changed. It would make sense to redefine the more concentrated and/or 
> longer-lived waste as high-level. Active recontainerization and 
> operational control must be provided for the entire hazardous life of 
> the waste, yet the NRC requires only 100 years of passive institutional 
> control. Thus, waste hazardous longer than 100 years could be forgotten. 
> Retrievability is essential. "
>

Actually, it would make more sense to use this stuff as fuel, rather than 
leave it as waste.