Use a radioactive eyepiece!

On Feb 1, 4:50*am, Helpful person wrote:
On Feb 1, 2:53*am, Martin Brown
wrote:









On 01/02/2013 04:35, RichA wrote:

On Jan 31, 8:42 am, Brad Guth wrote:
On Jan 31, 12:20 am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. *Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.

A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. *The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in *the lens.

I hate to agree with the Venusatic but he is closer than you are to the
truth. Assuming that the banana and thorium glass have equal weight.

Banana * * K40 0.01% half life 1.25 x 10^9 *= 32 Bq
Eyepiece * Th232 40% half life 1.4 x 10^10 *= 1.7 Bq

There is 4000x more thorium but it is approx exp(12).40/232 times less
radioactive per unit mass = 160,000 x 5.8 = 944,000

So although there is 4000x more thorium the thorium itself provides only
1/230 th of the dose from the banana. The faster decaying daughter
nucleides are responsible for the rest which is another factor of 12 in
output down to stable Pb208 (and fast enough to ignore half lives).

So the ball park numbers for the eyepiece vs the banana is that weight
for weight the banana is 20x more radioactive than the eyepiece. But K40
is an 90% beta and 10% gamma emitter doing little real damage.

However, the eyepiece emits much more damaging alpha particles and by a
happy coincidence that Q factor for radiation damage is 20.

So in terms of biological damage the eyepiece and the banana are
probably about equal. Old uranium glass is more impressively radioactive
even though the amount used to colour it is much smaller.

I wouldn't worry about using the eyepiece or eating a banana either.

--
Regards,
Martin Brown

Except you ingest the banana. *If the Thorium is mainly an alpha
emitter and it is in an interior lens then the radiation will not
reach the eye.

http://www.richardfisher.com

Perhaps if that thorium lens were twelve foot thick and being targeted
by a sufficient number of protons, it could get interesting.
Otherwise as you say, its relatively harmless if it's only at best an
alpha emitter.

On Feb 1, 10:04*am, Brad Guth wrote:
On Jan 31, 8:35*pm, RichA wrote:









On Jan 31, 8:42*am, Brad Guth wrote:

On Jan 31, 12:20*am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. *Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.

--
Regards,
Martin Brown

A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. *The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in *the lens.

A half gram of potassium 40 stuck up against your eyeball would not be
such a good idea. *Thorium is essentially inert unless it's getting
externally nailed by protons or otherwise activated. *It takes a
sphere of roughly 6 foot diameter of pure thorium in order to even
sustain itself.

What does sustain itself mean?

On Feb 1, 2:53*am, Martin Brown
wrote:
On 01/02/2013 04:35, RichA wrote:









On Jan 31, 8:42 am, Brad Guth wrote:
On Jan 31, 12:20 am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. *Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.

A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. *The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in *the lens.

I hate to agree with the Venusatic but he is closer than you are to the
truth. Assuming that the banana and thorium glass have equal weight.

Banana * * K40 0.01% half life 1.25 x 10^9 *= 32 Bq
Eyepiece * Th232 40% half life 1.4 x 10^10 *= 1.7 Bq

There is 4000x more thorium but it is approx exp(12).40/232 times less
radioactive per unit mass = 160,000 x 5.8 = 944,000

So although there is 4000x more thorium the thorium itself provides only
1/230 th of the dose from the banana. The faster decaying daughter
nucleides are responsible for the rest which is another factor of 12 in
output down to stable Pb208 (and fast enough to ignore half lives).

So the ball park numbers for the eyepiece vs the banana is that weight
for weight the banana is 20x more radioactive than the eyepiece. But K40
is an 90% beta and 10% gamma emitter doing little real damage.

However, the eyepiece emits much more damaging alpha particles and by a
happy coincidence that Q factor for radiation damage is 20.

So in terms of biological damage the eyepiece and the banana are
probably about equal. Old uranium glass is more impressively radioactive
even though the amount used to colour it is much smaller.

I wouldn't worry about using the eyepiece or eating a banana either.

--
Regards,
Martin Brown

Here is a shot of the lens. Try getting any kind of reading from a
banana with a geiger counter. Maybe from a truck full.
The CPM is approx 12x the background. The count jumps to 1000cpm when
an alpha probe is exposed to the bottom element, no alpha is see at
the eye lens.

http://www.pbase.com/andersonrm/image/148573186

On 01/02/2013 15:33, RichA wrote:
On Feb 1, 10:04 am, Brad Guth wrote:
On Jan 31, 8:35 pm, RichA wrote:

On Jan 31, 8:42 am, Brad Guth wrote:

On Jan 31, 12:20 am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.


A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in the lens.

A half gram of potassium 40 stuck up against your eyeball would not be
such a good idea. Thorium is essentially inert unless it's getting
externally nailed by protons or otherwise activated. It takes a
sphere of roughly 6 foot diameter of pure thorium in order to even
sustain itself.

What does sustain itself mean?

A big enough lump of Th232 would eventually reach critical mass since
neutron capture by the bulk material to produce more fissile U233 sets
up a chain reaction. This method has been advocated for using a thorium
fuel cycle. (although using a rather more controlled approach)

Don't know if his numbers are right or not.

--
Regards,
Martin Brown

On 1/31/13 8:45 PM, RichA wrote:

Unless they had fax machines in WW2...

Machines recognizable as "Fax Machines" have existed since 1881.

On 01/02/2013 15:46, RichA wrote:
On Feb 1, 2:53 am, Martin Brown
wrote:
On 01/02/2013 04:35, RichA wrote:









On Jan 31, 8:42 am, Brad Guth wrote:
On Jan 31, 12:20 am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.

A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in the lens.

I hate to agree with the Venusatic but he is closer than you are to the
truth. Assuming that the banana and thorium glass have equal weight.

Banana K40 0.01% half life 1.25 x 10^9 = 32 Bq
Eyepiece Th232 40% half life 1.4 x 10^10 = 1.7 Bq

There is 4000x more thorium but it is approx exp(12).40/232 times less
radioactive per unit mass = 160,000 x 5.8 = 944,000

So although there is 4000x more thorium the thorium itself provides only
1/230 th of the dose from the banana. The faster decaying daughter
nucleides are responsible for the rest which is another factor of 12 in
output down to stable Pb208 (and fast enough to ignore half lives).

So the ball park numbers for the eyepiece vs the banana is that weight
for weight the banana is 20x more radioactive than the eyepiece. But K40
is an 90% beta and 10% gamma emitter doing little real damage.

However, the eyepiece emits much more damaging alpha particles and by a
happy coincidence that Q factor for radiation damage is 20.

So in terms of biological damage the eyepiece and the banana are
probably about equal. Old uranium glass is more impressively radioactive
even though the amount used to colour it is much smaller.

I wouldn't worry about using the eyepiece or eating a banana either.

Here is a shot of the lens. Try getting any kind of reading from a
banana with a geiger counter. Maybe from a truck full.
The CPM is approx 12x the background. The count jumps to 1000cpm when
an alpha probe is exposed to the bottom element, no alpha is see at
the eye lens.

http://www.pbase.com/andersonrm/image/148573186

So about 1uSv/hr compared to banana equivalent dose 0.1Sv/hr.
All food consumed in a year is about 400uSv out of 4mSv or so in total.

http://en.wikipedia.org/wiki/Banana_equivalent_dose

Alpha particles get stopped by a piece of paper.

Potassium radioactivity is measurable with the right kit. eg

http://www.nuc.berkeley.edu/node/4742


--
Regards,
Martin Brown

On Feb 1, 10:55*am, Martin Brown
wrote:
On 01/02/2013 15:33, RichA wrote:









On Feb 1, 10:04 am, Brad Guth wrote:
On Jan 31, 8:35 pm, RichA wrote:

On Jan 31, 8:42 am, Brad Guth wrote:

On Jan 31, 12:20 am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. *Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.

A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. *The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in *the lens.

A half gram of potassium 40 stuck up against your eyeball would not be
such a good idea. *Thorium is essentially inert unless it's getting
externally nailed by protons or otherwise activated. *It takes a
sphere of roughly 6 foot diameter of pure thorium in order to even
sustain itself.

What does sustain itself mean?

A big enough lump of Th232 would eventually reach critical mass since
neutron capture by the bulk material to produce more fissile U233 sets
up a chain reaction. This method has been advocated for using a thorium
fuel cycle. (although using a rather more controlled approach)

Don't know if his numbers are right or not.

--
Regards,
Martin Brown

Yes, as a side issue, there doesn't seem to be much enthusiasm for
thorium reactors despite supposed benefits. They need some kind of
initiator to start the fusion process, correct?

On Feb 1, 11:42*am, Martin Brown
wrote:
On 01/02/2013 15:46, RichA wrote:









On Feb 1, 2:53 am, Martin Brown
wrote:
On 01/02/2013 04:35, RichA wrote:

On Jan 31, 8:42 am, Brad Guth wrote:
On Jan 31, 12:20 am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. *Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.

A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. *The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in *the lens.

I hate to agree with the Venusatic but he is closer than you are to the
truth. Assuming that the banana and thorium glass have equal weight.

Banana * * K40 0.01% half life 1.25 x 10^9 *= 32 Bq
Eyepiece * Th232 40% half life 1.4 x 10^10 *= 1.7 Bq

There is 4000x more thorium but it is approx exp(12).40/232 times less
radioactive per unit mass = 160,000 x 5.8 = 944,000

So although there is 4000x more thorium the thorium itself provides only
1/230 th of the dose from the banana. The faster decaying daughter
nucleides are responsible for the rest which is another factor of 12 in
output down to stable Pb208 (and fast enough to ignore half lives).

So the ball park numbers for the eyepiece vs the banana is that weight
for weight the banana is 20x more radioactive than the eyepiece. But K40
is an 90% beta and 10% gamma emitter doing little real damage.

However, the eyepiece emits much more damaging alpha particles and by a
happy coincidence that Q factor for radiation damage is 20.

So in terms of biological damage the eyepiece and the banana are
probably about equal. Old uranium glass is more impressively radioactive
even though the amount used to colour it is much smaller.

I wouldn't worry about using the eyepiece or eating a banana either.

Here is a shot of the lens. *Try getting any kind of reading from a
banana with a geiger counter. *Maybe from a truck full.
The CPM is approx 12x the background. *The count jumps to 1000cpm when
an alpha probe is exposed to the bottom element, no alpha is see at
the eye lens.

http://www.pbase.com/andersonrm/image/148573186

So about 1uSv/hr compared to banana equivalent dose 0.1Sv/hr.
All food consumed in a year is about 400uSv *out of 4mSv or so in total..

http://en.wikipedia.org/wiki/Banana_equivalent_dose

Alpha particles get stopped by a piece of paper.

Makes a quick way to separate them out from the beta and gamma.

Potassium radioactivity is measurable with the right kit. eg

http://www.nuc.berkeley.edu/node/4742

Yes, the Ludlum machines are very nice, especially equipped with a
pancake probe.

On Feb 1, 7:33*am, RichA wrote:
On Feb 1, 10:04*am, Brad Guth wrote:









On Jan 31, 8:35*pm, RichA wrote:

On Jan 31, 8:42*am, Brad Guth wrote:

On Jan 31, 12:20*am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. *Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.

--
Regards,
Martin Brown

A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. *The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in *the lens.

A half gram of potassium 40 stuck up against your eyeball would not be
such a good idea. *Thorium is essentially inert unless it's getting
externally nailed by protons or otherwise activated. *It takes a
sphere of roughly 6 foot diameter of pure thorium in order to even
sustain itself.

What does sustain itself mean?

It means nuclear fissions, as found within a thorium fueled reactor
designed to generate superheated steam of 650~850 F, requires a
volumetric cross-section of 6+ feet in order for that volume of
thorium fuel to sustain its own fission.

On Feb 1, 12:06*pm, RichA wrote:
On Feb 1, 10:55*am, Martin Brown
wrote:









On 01/02/2013 15:33, RichA wrote:

On Feb 1, 10:04 am, Brad Guth wrote:
On Jan 31, 8:35 pm, RichA wrote:

On Jan 31, 8:42 am, Brad Guth wrote:

On Jan 31, 12:20 am, Martin Brown
wrote:

On 31/01/2013 00:22, RichA wrote:

The Kodak Ektamate and Ektar lenses all use thorium glass. *Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

The half life of natural Thorium 232 is 3x the age of the Earth and
something similar for Lanthanum 138 rare earth glasses. The only worry
with the latter is that uranium was often present as an impurity.

A banana offers a thousand times as much radiation as any thorium
glass.

Uh, no. *The amount of potassium 40 in the banana is FAR lower than
the (up to 40% of thorium oxide) in *the lens.

A half gram of potassium 40 stuck up against your eyeball would not be
such a good idea. *Thorium is essentially inert unless it's getting
externally nailed by protons or otherwise activated. *It takes a
sphere of roughly 6 foot diameter of pure thorium in order to even
sustain itself.

What does sustain itself mean?

A big enough lump of Th232 would eventually reach critical mass since
neutron capture by the bulk material to produce more fissile U233 sets
up a chain reaction. This method has been advocated for using a thorium
fuel cycle. (although using a rather more controlled approach)

Don't know if his numbers are right or not.

--
Regards,
Martin Brown

Yes, as a side issue, there doesn't seem to be much enthusiasm for
thorium reactors despite supposed benefits. *They need some kind of
initiator to start the fusion process, correct?

Thorium doesn't create weapons grade secondaries, so the Pentagon, DoD
and oligarchs invested in those are always 100% opposed to any use of
thorium that's also failsafe as well as the all-inclusive (birth to
grave) cost of its clean and/or environmentally friendly energy to the
end-use customers would not have to cost at most 10% of what we're
currently paying.