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Chernobyl
A FEW more elements of truth about the cause of the Chernobyl disaster emerged from the post mortem meeting held recently at the International Atomic Energy Agency in Vienna. This was despite the whitewash thrown over the proceedings by the 540 (pro)nuclear experts who attended.
As predicted in the last issue of the MIR, the Soviet scientists present put the emphasis of the blame on individual errors and poor safety procedures. The key question, however, is whether there is a fail safe mechanism in the reactor which would operate after unforeseen accidents caused by negligence or other factors. The most important fact to emerge in Vienna was that this definitely was not the case.
The cause of the explosion, as predicted in the last MIR, lay in the effects of a sudden power surge which was the result of a positive feedback control system in
the reactor. The positive feedback effect meant that the hotter the reactor became the more steam was generated at the core. This in turn ied to a faster nuclear reaction which caused the reactor to get even hotter and so on. This growing chain reaction is essentially what happens in an atomic explosion and the initial explosion at Chernobyl was really a small scale nuclear bomb going off.
The positive feedback mechanism is a basic design flaw of the RBMK reactor installed at Chernobyl and at many other sites. It results from having the nuclear reaction moderated (slowed down and controlled) by graphite and the cooling done primarily by water. The technical details are complex but during an accident this design combination can lead to catastrophe. The potential for disaster due to this design flaw has been known to the Russians for at least two years and has been discussed in their technical press.
The
reasons
why the
By Pete Dickenson
NUCLEAR
TIME BOMB
ORIAISOCIALISTENERGY PLANS
A MiMant PAMpMEn
50p
pears to have been aimed at
was to keep the cooling
system working even if the
reactor was shut down. This
would greatly speed up the
process of getting the reac-
tor going again once a fault
had been fixed.
Despite the evidence of
the dangerous design
features of the RBMK reac-
tor the bureaucrats intend to
carry on as before. Output
from RBMKs will reach 90%
of pre-Chernobyl levels by
next year.
Nuclear Time Bombor a socialist energy plan? A Militant pamphlet, 60 postage included, from World Socialist Books,, 3/13 Hepscott Road, London E9 5HB.
operators were conducting the experiment which led.to the accident now appear to be linked to the power crisis in the Soviet Union. Nuclear power stations are usually operated to provide "base load" electricity, that is they operate 24 hours a day because it is difficult and time consuming to stop and start a reactor. If there are frequent faults which means the reactor has to be switched off its efficiency is drastically reduced.
What the experiment
Industrial noise
danger
ONLY ONE firm has ever been prosecuted for deafening its workers yet hundreds of thousands have gone partially deaf as a result of industrial noise Wew Scientist, 5th December 1985.)
The level of noise is measured in decibels (dB). Although the louder a noise appears the higher the decibel rating will be, it is not true that a doubling of the noise level will double the number of decibels because of the way decibel readings are calculated. In fact as a noise gets louder, the decibel reading increases proportionately less and less. This means that according to the official code being exposed to 90 decibels noise for 8 hours is considered safe although it is
only considered safe to be exposed to 108 decibels of noise for 7½ minutes. If these limits are exceeded some permanent deafness can result and in fact noise levels below these government norms can cause permanent hearing loss. It is also important to consider the frequencies (pitch) of the noise. Certain of these correspond to speech and it is obviously more serious to be deaf to typical speech frequencies than it is to the noise-of a jet roaring overhead, for example. Noise levels of over 100 dB are common in British industry. In a bottling plant in Scotland a noise of 131 dB was measured, fourteen times the official limit. Agricultural workers are not only in danger from tractor and machinery noise but also from pigs. At feeding time the noise of pigs squealing reaches 108 dB
according to the agricultural inspectorate, a level at which a worker would receive his or her daily safe dose in 7½ minutes.
The planet Uranus
THE SPACE probe Voyager 2 has revealed new secrets about the planet Uranus, more than 2,000 million miles away. Before Voyager virtually all that was known about the planet was that it was four times the size of the Earth, orbits the sun every 84 years and has a series of five moons and nine rings.
Voyager found that the planet rotates on its own axis every seventeen hours and has surface winds blowing at about 400 miles per hour. Ten new moons were discovered, much smaller than the five that can be
seen from the Earth.
One of the most interesting discoveries was that the magnetic field is tilted at 60 degrees to the axis of rotation of the planet (in the case of the Earth this would mean that the South Pole would be near Los Angeles). Astronomers believe that a planet's magnetic field is generated by a region of electrically conducting liquid near its centre. Uranus probably has a small rocky core overlain with an ocean of hot water and topped with an atmosphere of hydrogen. The most likely region for generating magnetism is the bottom of the ocean layer, where, the oxygen and hydrogen from the water form a metallic liquid with carbon and nitrogen. Voyager is now on its way to Neptune which it will reach in August 1989
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