From: George Murphy (gmurphy@raex.com)
Date: Sun Jun 01 2003 - 14:26:05 EDT
Larry -
I appreciate the historical insights from you and Moorad. Concerning the
original question about the source of tritium for the D-T reaction, I quote from the now
ancient (1960) _Project Sherwood_ by Amasa Bishop:
"In addition, since tritium does not occur naturally in nature (sic!), the
neutrons (from the D-T reaction) must be used to regenerate the tritium from lithium, by
means of the reaction
n + Li6 -> T + He4 + 4.8 MeV.
In this way the tritium may be completely recovered. Thus, it acts as a sort of
catalyst for the reaction, the fuel actually consumed being deuterium and lithium."
My own experience with plasma physics has been wholly theoretical, an offshoot
of my Ph.D. work on MHD in general relativity. & my only encounter with the hazards of
tritium was when somebody in the spectroscopy lab at Hopkins broke a tube of it, causing
a shut-down of the building.
Shalom,
George
Lawrence Johnston wrote:
>
> Moorad - thank you for the information on your Advisor, Emil
> Konopinski, and his calculations of the D-T reaction. Emil was a
> good friend of MY thesis advisor, Luis Alvarez. I think I met
> Emil at a party at Alvarez' house, in 1944. His calculations
> were good, but I guess Oppenheimer did not sufficiently trust
> their calculations of the Fat Man bomb's energy release.
>
> Just as Alvarez and I (and Wolfgang Panofsky) were about to take
> off in our instrumented B-29 to make measurements of the Trinity
> test, July 16, 1945, Oppenheimer called Alvarez and ordered him
> to stay at least 25 horizontal miles from the Alamogordo Trinity
> test site, since he felt unsure of the bomb's energy output. We
> were planning to use the Trinity explosion as a dress-rehearsal
> for our soon-to-come measurements of the energy output of the
> bombs that were later dropped on Hiroshima and Nagasaki. Our
> measurements were not needed for the Trinity test itself, since
> there was a large amount of instrumentation on the ground. Most
> of those detectors were blown up in the explosion, but not before
> their output was recorded remotely behind the personnel bunkers.
>
> We took off anyway from Kirtland Airforce base, and went through
> our routine drop of parachute gages at 30,000 feet altitude,
> while we listened by radio to the countdown from the ground
> bunker for the explosion on top of the steel tower. When the
> bomb went off as hoped for, all of us were thankful that our
> particular components of the Implosion system worked. If it had
> fizzled, we would forever since have wondered if the fizzle was
> our fault. And of course I was thanking The Lord. Alvarez was an
> atheist so I don't know whom he was thanking.
>
> Thanks, Moorad. Larry Johnston
>
> =======================================================
> Lawrence H. Johnston home: 917 E. 8th st.
> professor of physics, emeritus Moscow, Id 83843
> University of Idaho (208) 882-2765
> Fellow of the American Physical Society
> http://www.uidaho.edu/~johnston/homepage.html =========
>
> Moorad Alexanian wrote:
>
> > It was Emil J. Konopinski, my PhD thesis advisor, who suggested when
> > at Los Alamos the use of D-T (deuterium-tritium) rather than D-D
> > reaction for the atomic bomb owing to the larger cross section of the
> > D-T reaction. He was also the one who calculated that the explosion of
> > an atomic bomb in the atmosphere would not ignite the atmosphere; such
> > were the fears and the unknowns of the early nuclear efforts.
> >
> >
> >
> > Moorad
> >>
> > Tritium http://www.triumf.ca/safety/rpt/rpt_8/node8.html
>
> > _____ > Tritium is an isotope of hydrogen which has one proton and
> > two neutrons . It emits beta particles only and has a half-life of
> > 12.3 years. The maximum beta energy is 18 keV, and the mean beta
> > energy is 6 keV. A beta particle with energy of less than 70 keV will
> > not penetrate the dead outer layer of the skin. Therefore, tritium is
> > not an external radiation hazard , but when taken into the body it
> > becomes an internal hazard .
> >
> > Tritium is produced in accelerator cooling water systems which are
> > subjected to large proton or neutron fluxes such as those of the meson
> > production targets of the TRIUMF 500 MeV facility. The tritium is
> > produced by spallation reactions with oxygen, nitrogen and carbon
> > nuclei present in the water systems and to a much lesser degree by
> > radiative capture of neutrons by the deuterium nuclei in water. The
> > tritium atom then combines with a hydrogen and oxygen atom to form
> > the molecule HTO, often called tritiated water.
> >
> > Tritium does not contribute any significant part of the dose at
> > TRIUMF, and most uptakes would be acute rather than chronic.
> >
> > Uptakes of tritium usually result from inhalation and skin absorption,
> > but ingestion is also possible. The blood distributes tritiated water
> > equally among all the body fluids, just as it does with normal water.
> > All the soft tissues in the body will be irradiated by the decaying
> > tritium and they constitute 90% of the body weight. As a result any
> > tritium in the body will lead to a whole body equivalent dose .
> >
> >
-- George L. Murphy gmurphy@raex.com http://web.raex.com/~gmurphy/
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