Re: Criticality accidents

Dear Leader <spamless@xxxxxxxxxxxx> wrote:
Criticality accidents have occurred both in the context of nuclear weapons
and nuclear reactors.

a.. On 21 August 1945, Los Alamos scientist Harry K. Daghlian, Jr.
suffered fatal radiation poisoning after dropping a tungsten carbide brick
onto a sphere of plutonium. The brick acted as a neutron reflector, bringing
the mass to criticality.
a.. Nine months later, another scientist, Louis Slotin accidentally
irradiated himself during a similar incident, when a critical mass
experiment with the very same sphere of plutonium took a wrong turn.
Immediately realizing what had happened he quickly disassembled the device,
likely saving the lives of seven fellow scientists nearby. Slotin succumbed
to radiation poisoning nine days later.
a.. On 15 October 1958, a criticality excursion in the heavy water RB
reactor at the Boris Kidric Institute of Nuclear Sciences in Vinca,
Yugoslavia killed one and injured five.
a.. On 23 July 1964 - Wood River Junction facility in Charlestown, Rhode
Island. A criticality accident occurred at the plant, designed to recover
uranium from scrap material left over from fuel element production. An
operator accidentally added a concentrated uranium solution to an agitated
tank containing sodium carbonate, resulting in a critical nuclear reaction.
This criticality exposed the operator to a fatal radiation dose of 10,000
rad (100 Gy). Ninety minutes later a second excursion happened, exposing two
cleanup crews to doses of up to 100 rad (1 Gy) without ill effect.[2]
a.. On 23 September 1983, an operator at the RA-2 research reactor in
Constituyentes, Argentina received a fatal radiation dose of 3700 rads (37
Gy) while changing the fuel rod configuration with moderating water in the
reactor. Two others were injured.
a.. Between June 24, 1990 and July 1, 1990, about four years after the
Chernobyl accident, signs of a sub-critical neutron multiplication event
occurred inside room 304/3 at the damaged reactor (see Russian Research
Centre Kurchatov Institute report). The neutron increase was by a factor of
about 60, much less than the increase that would result from a criticality.
A gadolinium solution was injected to absorb neutrons and the neutron level
returned to the original level.
a.. In 1999 at a Japanese uranium reprocessing facility in Tokai, Ibaraki,
workers put a mixture of uranyl nitrate solution into a precipitation tank
which was not designed to dissolve this type of solution and caused an
eventual critical mass to be formed, and resulted in the death of two
workers from radiation poisoning.
Since 1945 there have been at least 21 deaths from criticality accidents; 7
in the United States, 10 in the Soviet Union, 2 in Japan, 1 in Argentina,
and 1 in Yugoslavia. 9 have been due to process accidents, with the
remaining from research reactor accidents.

For the year 2000, in California alone there were 118 deaths and
12,074 injuries for bicyclists.

For the years 2000-2005, in California alone there were 24,366 deaths
due to traffic accidents.

For the years 1980-1995, there were 17,000 construction worker deaths
in the US alone.

What's your point?


--
Jim Pennino

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