As the mining work was being completed, the explosives which comprised
a total of 4,170 lb of RDX TNT in 12 lb packs, were brought up to the
mine in a military powder wagon under heavy police guard. At the Lucy
Level entrance the explosives, still in their wooden transit cases,
were taken from the powder wagon and loaded onto the mine wagons which
were ready coupled onto the Lucy loco, waiting at the adit mouth. Each
wagon carried 240 lb of RDX TNT, in four wooden boxes. Safety precautions
were rigidly enforced: no smoking was permitted within twenty yards
of the powder wagon and the vehicle remained under police surveillance
from the time it arrived until it had been fully unloaded. The Lucy
loco pulled its delicate cargo at a sedate 4 to 5 mph along the 1,300
yards of track to the top of Smith's Shaft, where each wagon was detached
from the train, put singly into the cage and lowered to the 90 fm level.
Here the process was repeated, each wagon was pushed the 200 feet from
the bottom of Smith's Shaft to the top of Murray's Shaft and lowered
down the incline to the 175 fm level. On arrival the trucks were again
propelled by hand about 700 yards southwards along the 175 fm level
and the West Crosscut, where they were unloaded, the charges removed
from the boxes, and the empties returned. While the explosives were
being carried down the mine, all normal activity was suppressed to minimise
the risk of an accident.
The big charge was put into the chamber first and some rather surprised
seismologists who had come to the chamber once their work was done to
while away an hour or so watching a photographic session, were cheerfully
volunteered by their boss, Dr Eric Carpenter, to help load the packs
of TNT onto the wooden platform which occupied the centre of the chamber.
Peter Marshall and Ron Burch were amongst this group and they vividly
recollect the work, lifting and stacking the packs of explosives, while
a group of photographers, electronic flash units popping merrily, recorded
their nervous endeavours.. The 3,010 lb charge consisted of 7 layers
of 36 boxes, each box weighing 12 lb. Multipoint detonation was used,
employing 36 detonators embedded amongst the TNT and connected by wires
to the firing circuits. A smaller charge of 1,160 lb was packed firmly
into the small crosscut, then the detonators were put in place and connected
into the cables of the firing system.
Once both charges were in place the West Crosscut was sealed by a heavy stemming. The change to adapting the main crosscut level for a chamber meant that the 6 ft wide level had to be filled rather than the small tunnel originally envisaged, and this posed a major problem. Normally a concrete plug would have been used, but this could not be constructed in the short time available. On the advice of Major Kerr, the stemming was made up of sandbags filled with tailings from the mine dam, interspaced with gaps and timber walls. The main stemming for the decoupled charge filled the level back beyond the position of the coupled charge so that it formed an integral part of both. Sand was again used for the stemming of the coupled charge, the crosscut being filled, then the West Crosscut stemmed for a distance of 15 ft each way from the little crosscut.
Two of the AWRE men assembling the decoupled charge on a wooden platform in the middle of the egg-shaped chamber at the end of the West Crosscut. Dr. Eric Carpenter is lifting a pack of TNT from its box and Ron Burch is on the ladder behind him.
Both charges and the stemming were put in place by 17th December 1959, when the West Crosscut was sealed by two brick walls, one in the crosscut and one in the nearby South Drive.
The equipment which would fire the charges was installed in the
West Crosscut at a point 285 ft from the smaller coupled charge,
and was controlled from the surface.
Meanwhile the seismologists were making their own preparations. There was some difficulty at first in finding enough equipment for the Cornish (Excelsior Tunnel) and Cumbrian tests, but four sets of shortperiod Willmore seismometers were ordered, each of which could simultaneously measure vibrations vertically and in two horizontal directions, and with other equipment already available, enough equipment for six measurement sites was collected and sent to Greenside.
An enormous amount of cabling was also needed for the detonation and
safety systems associated with the firing of the charges and this was
brought on a trailer pulled by a huge and immensely powerful military
transporter called a Matador. The Matador could haul its cargo of cable
drums and machinery at a maximum speed of 15 mph along the winding roads
to the test site. Ron Burch, one of the Foulness seismologists, accompanied
the driver of this vehicle on its journey, and he recollected that on
the way back they overtook Dr Barbara Moore, an anti-nuclear demonstrator
of the time, on one of her epic marches for peace. This lady covered
ground at a formidable rate, and the driver reckoned that it was a close
thing as to who would overtake who! This vehicle was parked up at the
mine beside the old lodging shop, now deserted, after unloading its
cargo. The miles of cable which connected the control and firing station,
set up in a wheeled trailer besides the Office, with the equipment in
the mine, were laid along the Lucy Level then threaded down the two
shafts to the 175 fathom level and along to the firing station in the
West Crosscut by the time the explosives had been put in place.
Six sites were selected for the seismometers at distances varying from half a mile to 47.5 miles, distances which were chosen to determine the limits at which the signals could be detected. Seismometers are almost unimaginably sensitive, for they are meant to record tiny vibrations from distant seismic disturbances. For example the detonation of a fully-coupled one kiloton nuclear device in what was then the Soviet Union would produce a vibrational movement of the ground of just one nanometre in the UK, a dimension which is about one fiftieth of the diameter of a flu virus!
Almost anything can produce vibrations of that size, so sites were chosen where there were no busy roads, trees through which the wind could whistle, or nearby becks which could mask the weak signals from the Greenside explosions with their own background noise. A nearby telephone link was essential in case radio communications failed at the critical time, for all the stations had to start recording just a few seconds before the detonation, and the time signal 'pips' on the BBC radio transmission or the GPO talking clock were used to obtain this precise timing. The sites which were selected for seismic recording were: 'Foulness Castle' NGR 364175, a code name invented by Eric Carpenter for the Pitchfords' house near the Low Mill, 0.5 miles from the test point, where the nearest seismometer was located; Low Hartsop NGR 412129, 4.5 miles from the mine at the end of the road running through the village; Outgang Farm, Helton, near Penrith NGR 506219, 9 miles from the mine in an old quarry near the lane leading up from Helton village; Dry Howe Farm, Selside, in Sleddale NGR 528021, 14 miles from the mine in a field to the south of the farm buildings in a fairly well wooded valley; Underwinder Farm, Sedbergh NGR 643927, 23 miles from the mine at a height of 600 feet up the side of a hill; Malham Village, Yorkshire NGR 903631, a site 47.5 miles from the mine in a field by the Malham to Malham Tam road on a limestone outcrop 300 yards from the village.
During installation and testing of the seismometers, several of these
very delicate instruments broke down, so this farthest site was abandoned
and the instruments moved to the other sites to replace the failed ones.
At Fowlness Castle two instruments were set behind a rough wall of stones
and turves, and protected from the elements by a plastic sheet. The
data from the instruments were transmitted through cables to the recorder
set up inside the Pitchford's cottage.
THE FIRST FIRINGS
The intention was to detonate the large decoupled charge first, then thirty minutes later on the next time signal, detonate the second fully-coupled charge. Before the first firing, an attempt was made to estimate the strength of the seismic signals which would be obtained from the tests by firing a small coupled charge in a 10 ft long hole in the 175 fathom level. This was a charge of 100 lb of Polar Ammon dynamite 'borrowed' from the Greenside Co. and it was detonated at 19.00 on 15th December 1959. Only the Foulness Castle station detected a signal from this explosion, so the scientists altered the amplification of the detectors to increase sensitivity.
The signal from the Foulness Castle Geophone detector recording the shock wave from the decoupled explosion
Now all was ready for the big event, the detonation of the 3,010 lb decoupled charge on which the future nuclear policy of the country depended. On Saturday 19th December the mine firing circuits were connected to the firing cables running through the stemming to the charge in the big chamber and the special interlock keys without which the firing equipment was inoperative were inserted. The mine was cleared of personnel, the entrance sealed, and the count-down commenced. At each of the five detection positions, two scientists crouched in the shallow holes or small enclosures which contained the seismometers, in radio and telephone contact with the firing trailer, ready to start their equipment on the radio time signal. A night firing was chosen so that the background noise from human activity would be at a low level and as the moment approached Harold Nobbs in the firing trailer fitted the Master Safety Key into the control panel, thus making contact with the slave control unit on the 175 fathom level and on the radio time signal for 22.30 the button was pressed.
On the surface there was a dull thudding noise and the remote seismograph
recorders fluttered briefly as they recorded the great event; it was
all over in less than a second. The second charge was then connected
to the firing circuit but to everyone's great disappointment it was
found that there was no electrical connection to the slave control system
which had been destroyed by the failure of the stemming. The firing
of the coupled charge would now have to wait until the damage was repaired,
so the AWRE men of the Measurement Group packed up and went home for
Christmas. Ominously, the Sedbergh seismometer twenty three miles from
the mine had been unable to detect the large decoupled explosion, giving
an early indication that the strength of the signal had been much weaker
than predicted and thus that decoupling might be even more effective
than they had estimated for large explosions. This result was communicated
to the negotiators at the Geneva talks, and the significance was not
lost on them.
There followed a period of waiting as the mine was cleared of noxious gases from the huge explosion. It had been calculated that the first charge would release over 20,000 ft of poisonous carbon monoxide, small amounts of hydrogen cyanide gas and nitric oxides and nearly 5,000 ft of explosive hydrogen gas, so the test area had been sealed off with brick walls and a large Roots blower installed to pump out the dangerous gases through a pipe into the shaft, fresh air coming in through a one-way valve in the wall to replace the exhausted gas. The blower was switched on before the detonation and although some of the containment walls were destroyed, the blower was undamaged and it was able to carry on clearing the air after the detonation. Re-entry of the mine was a dangerous process and this was carried out by trained rescue teams from Greenside and neighbouring mines who were used to wearing breathing apparatus; the 'greenhorn' AWRE men were banned from the mine until it was declared safe.
A PROTO closed circuit oxygen apparatus had been in standard use at
Greenside since the 1952 disaster and this equipment was used by the
men who worked their way down into the mine, checking it section by
section under the supervision of the Senior District Inspector of Mines
who was familiar with the workings. These men were equipped with portable
gas detectors, but also relied on an older and well proved technology,
for each man carried two canaries in cages, and had instructions to
proceed with great care if the birds should show any signs of distress.
As Officer-in-Charge, Mr Drake-Seager was allowed in during this work.
Cages of mice had also been left at strategic positions in the mine
before the charge was fired, so that if they were found alive afterwards
this would reassure the re-entry teams that no poisonous gas had reached
that point in the mine. Moving cautiously, fresh air bases were progressively
advanced in the mine by the masked re-entry teams, until finally the
Inspector informed Drake-Seager that normal entry without breathing
apparatus was permissible.
The Operations group then was allowed in and work commenced on repairing the damage to the stemming and control equipment so that the second charge could be fired. When the test site was examined, it was found that the stemming in the West Crosscut had failed to contain the blast and had been blown along the length of the level. The slave control equipment and firing cables for the second charge had been shot down into the far end of the West Crosscut and completely destroyed. The explosive charge and the detonators were still in place in the second crosscut and were usable, so cables were connected to them, then the stemming was replaced and the firing system restored. The work was completed early in January 1960, and the AWRE Measurements team returned for the second firing which was scheduled for 15th January.
TWO MEN DIE
During the night of 14th January 1960, the day before that scheduled for the firing of the coupled charge, a group of Greenside men were finishing their work in the West Crosscut level by sand-bagging the ventilation pipes under the supervision of the afternoon shift boss, John Pattinson Brown, known by his nickname 'Jackets'. Among them were William Sinkinson, who was twenty-three years old and a middle-aged man called Alex Santamara. These men were normally surface workers, and although Sinkinson had worked underground occasionally, neither were experienced miners. After the mid-evening break at about 9.00 pm the younger man took Santamara off to visit some of the stopes in the northern part of the mine which he had worked in some years before, where he said good pieces of white spar could be had for a garden decoration. Arnold Lewis was another of the miners and at about 10.30 pm he suddenly realised that the two men had not returned to work and told the shift boss. Brown called Fred Dawes over, for he thought the only place they could be was in a stope which Dawes used to work and the two men set off to look for them. There was no sign of the men in the 175 fathom level, so when they reached Dawes's Stope, Fred Dawes clambered up the 20 ft high waygate ladder. When only three steps up the ladder he realised that the air was tainted but he continued up with the smell getting stronger until he reached the top and peering into the gloom saw the motionless body of Alex Santamara lying on the lowest bench.
The two men went back to get the others and when they all arrived back at Dawes's Stope, Brown went to get a rope while Arnold Lewis and Fred Dawes climbed the waygate ladder and entered the stope. Lewis had been involved with the 1952 rescue attempt and recognized the presence of gas, but filling their lungs with air the two men dashed along the bench, seized the inert body of Santamara and hauled him back to the entry winze. Gasping and dizzy, they realised that they had been affected by gas and couldn't get the man down the ladder way, so they left him propped up close to the ladder where the air was freshest, and went down to get help. The returning shift boss met them as they got down into the level and Arnold Lewis just had time to warn him of the gas before passing out. Brown then telephoned Robert Corlett to call for a doctor and alert the rescue team and the alarm was raised.
Fortunately, since the next test was imminent, a fully equipped rescue
party could be called out immediately under the control of James Barnsley,
one of the Greenside hoist men. A small group of men, fully-equipped
with breathing apparatus was sent in to bring out the two men from the
stope and take their would-be rescuers to safety. Santamara was quickly
brought down into the 175 fathom level and even though there was no
sign of life he was given artificial respiration until Dr Armstrong
the village doctor arrived and confirmed that he was dead. Barnsley
and his men went back and found Sinkinson up in the stope wedged in
a hole near the top of another ladder and he too showed no signs of
life. The rescuers were able to move the body so that Barnsley could
get past to the top of the ladder and then lower it to the bottom bench,
but then they all had to retire from the gas-filled area and. go back
to the surface to change the breathing equipment. The tired men were
on the point of setting off once more when a fresh rescue team from
Kirkby Thore arrived and Barnsley led them back to the stope to recover
Sinkinson. Lewis and Dawes recovered from the effects of the gas, but
Santamara and Sinkinson had probably been long dead when they were first
News of fatalities in the mine was broadcast over the radio, but the
AWRE immediately telephoned the families of each of their men who were
working at Greenside to reassure them that their menfolk were not involved,
a thoughtful touch for which the men were deeply grateful. At the inquest
no blame was attached to the scientists who had failed to detect gas
in the old stopes, for the men had violated the Greenside Mine's own
Safety Code which expressly forbade entry into abandoned workings except
in the company of a responsible mine official. However the plucky rescue
attempt by Dawes and Lewis was universally praised and in the November
of that same year, the two were rewarded for their heroic efforts on
behalf of their fellow miners by the award of the Queen's Commendation
for Brave Conduct.
CONCLUSION OF ORPHEUS
The shocking deaths of the two men put a stop to all further work on Operation Orpheus for several weeks while the situation was reassessed. The Inspector of Mines had other commitments which prevented any further involvement with the project, so the AWRE Operations Group, their attention focused on the hazards of gas by the accident, sought the advice of a consultant, Professor Graham, who was an expert on gas and from a Mr. Carson of the National Coal Board who for some years had been involved with rescue and re-entry work in mines in the Northumberland area. On their advice the containment walls were strengthened and gas extraction improved by the installment of a new Roots blower with an extraction capacity four times greater than the previous blower.
Two seismographic detectors, a little Geophone and a large Willmore set on a handy rock in a shallow enclosure behind the Pitchford's house.
With a higher pressure extraction system, the danger of a hydrogen
explosion in the venting gas was considered worthy of attention and
an air bleed system was fitted into the vent pipes so that the gases
being dragged out of the explosion area could be diluted with fresh
air, thus keeping the hydrogen concentration well below the critical
level. The scientists changed their minds several times as to just where
the holes should be in the pipe which ran the length of Smith's Shaft,
and Harold Oglethorpe who was doing the work for them, his patience
wearing just a trifle thin, asked them quietly whether it would perhaps
better suit their requirements if he were to bore holes at one foot
intervals the length of the shaft so that they could choose which one
to use at their leisure? This gentle irony was taken in good humour
by the scientists.
Over three months after the accident, on Friday 29th April 1960, the mine was once again cleared of personnel and the countdown commenced for the detonation of the fully-coupled 1,160 lb charge of RDX TNT. This time all went smoothly and according to plan; at precisely 19.00 the button was pressed and the seismometers at all sites recorded the shock. Background noise was very much lower than it had been before Christmas and clear traces were obtained. The venting of the mine and checking for gas was carried out a great deal more thoroughly after this second test, so it was some time before the mine was declared safe once more.
Despite the trouble with some of the seismometers and all the unknowns
in the settings. to be used, the Greenside tests were a resounding success,
giving the UK scientists a world lead in this strategically important
area. Analysis of the results was conclusive: the signal from the smaller
coupled charge was much bigger than that from the large decoupled charge,
suggesting a decoupling attenuation of the signal by a factor of between
10 and 30. The Latter theory worked for large explosions! Talks continued
with the Russians for a while but the problem of verification was insoluble
and in August 1961 the Soviet Union resumed its nuclear testing programme;
the test ban treaty was in the dustbin.
In 1963 efforts were renewed and a partial treaty was concluded which banned nuclear tests in space, in the atmosphere and underwater. Underground tests were still and even today, remain a problem, for in the intervening period decoupling methods have been improved to give attenuation factors of 70 or more for nuclear explosions, so that even with the more sensitive detection systems now available, a decoupled explosion would be hard to detect with a seismometer. Satellite surveillance systems incorporating remote sensing devices are now so highly developed that even underground explosions are difficult to hide, but decoupling is still a problem: very small nuclear explosions can be effectively decoupled and made totally invisible from the air.
© 2004 Subterranea Britannica