Re: Yucca Mtn. This should raise some hackles

[Bernard Cleyet <anngeorg@PACBELL.NET>]

"Also, the shorter half-life means higher energy radiation, which further
increases the danger."


This is certainly true for Alpha decay, but I don't think so for gammas,  i.e.
the energy of the excited state of a daughter is not easily related to the
half life of the parent, yes?

For Betas, I estimate the six order change in 1/2 life results in ~ 40 X
increase in end point energy (assuming similar matrix elements).  In both
cases "so what":  A sheet of paper will stop the most energetic Alphas, and a
few inches of concrete the Betas.

bc who has measured (lab exercise) the specific activity of a nuclear species
(K-40) to determine its half life

P.s.  Radioactive fallout intensity is ~ T^-1.2 from ~ten min. to 200 days or
a reduction in activity of 4* E-6; after that it is more rapid.  This is a
result of the varying half lives of > 200 isotopes of 36 elements.  (The
gasses krypton and xenon are not included.)    A further reduction to 1*E-9 is
reached in 25 years.  This is a drop in the bucket considering the two ounces
of fission products per kiloton yield is, in gamma activity, equivalent to
30,00 TONS of radium in equilibrium with its daughters!!!!  (Remember one
milligram of radium has an activity of one milliCi.)  As the shorter isotopes
decay the rate will approach exponential decay.  quick calc.:  initial 2 oz.
(2.7E10 Ci) in 25 years is 270 Ci or 4.8 Ci / initial gram of fission
products.  The power station's waste will additionally include depleted U -- ~
10E9 yr. half life?   (source:  Glasstone, 'The Effects of Nuclear Weapons"
1962)


Tim Folkerts wrote:

> > BTW, why are we so much more worried about shipping spent rods than
> > fresh ones, which are being shipped all the time with no apparent
> > controversy. There may be a good explanation for this. I just don't
> > know one.
>
> I was wondering about this too, but then had an idea.  Presumably the mass
> & volume are similar before and after use.  However, the uranium fuel has a
> 1/2 life of ~10^9 years, while the waste is ~10^3 yr.  This means an equal
> amount of material is 10^6 more radioactive.  Also, the shorter half-life
> means higher energy radiation, which further increases the danger.
>
> Tim Folkerts
> Department of Physics
> Fort Hays State University
> Hays, KS  67601
> 785-628-4501