Dramatic Time Events
Dramatic chasms in time
by Roberto Vacca (Traduzione di Leonardo Pavese)
We use the dates of significant events
to mark periods of time or the beginning of new eras. World War II ended in the
summer of 1945. Since then, we have been in the “postwar time.” This new era is
not only marked by a conventional date, but also by new concrete factors among
which there is the entity of atmospheric radioactivity and its consequences.
Among the sources of natural atmospheric
radioactivity, the polluting radon gas is at the top of the list. Radioactive radon
is produced by the natural decaying of the uranium chain. Cosmic rays are
another important source of radioactivity in the air.
The artificial causes are the use
of radioactive materials in healthcare, scientific research and radiotherapy;
the clean-up of contaminated sites and the rare accidents in nuclear powerplants
like the ones of Chernobyl and Fukushima.
The radioactive elements in the atmosphere
are many: C-14, Cesium 137, Cobalt 60, Thorium 232, Beryllium 7, Sodium 22
derived by the residuals of the atomic bombs detonated in march 1945 in New
Mexico, U.S.A., during WWII over Hiroshima
and Nagasaki Japan; in accidents with loss of plutonium of the American artificial
satellite SNAP (System for Nuclear
Auxiliary Power) 9A in 1964, of a module of the Apollo 13 spacecraft (1970) and
by the over 2000 atomic explosions that occurred since 1945.
The abovementioned radioactive substances are present in traces that are not dangerous for living beings. However, they are incorporated from atmospheric oxygen in the steel and in the lead used for industrial productions. So, contaminated steel cannot be used to make high precision devices (like Geiger counters, for example), that are used to measure the exposure to radiation of the people who work with radioactive materials or in diagnostic CAT-scan or MRI machines. To this day, low radioactive background steel produced before 1945 is still used for the making of those highly sensitive machines. That steel can be found in great quantity in the wreckages of ships sunk during the early years of WWII. The case of the British 8500 tons heavy cruiser HMS Exeter, sunk by Japanese aircraft in 1942 in the Java Sea is very interesting.
 |
| HMS under Japanese attack, February 15.1942 |
The ship wreckage was found in 2007, but ten years later another Royal Navy search party found that it was almost gone. Many tons of steel originally produced in the Davenport steel mills in 1931 had been taken and sold at a remunerative price. Similar fate had the wreckages of ships of the Imperial German Navy sunk in Scapa Flow, Orkney Islands, Scotland, during the First World War.
Beginning in 2017, the Italian National
Nuclear Physics Institute in its Underground Cryogenic Observatory under 4600’
of rock in the Gran Sasso tunnel carried out several accurate experiments on
the Beta double decaying without emission of neutrinos. It is noteworthy that
the temperature reached during the experiments was 0,01° Kelvin, just 1/100 of
a degree above absolute zero.
The instruments employed were shielded with non-radioactive lead sheets provided by the Civic Museum of Cabras, Oristano, Sardinia, Italy, taken form a load of 1000 lead ingots salvaged from the wreckage of 1st century Roman ship at the depth of 118’ near the Island of Malu Entu. And even the lead from unearthed stain glass windows of medieval churches was used to produce non-radioactive shielding.
Roberto Vacca (1927) by training is an engineer and a computer scientist. He has taught at universities in Rome and Milan, but has achieved fame in Italy and abroad as a science writer and as a fiction author. Probably his most famous novel is "Death of Megalopolis" (1974). On this blog there are several translations of his writings that can found by searching for his name.
Your comments, as always, will be greatly appreciated.
Thank you,
L. Pavese
Comments
Post a Comment