|Silent but deadly danger|
In common with a lot of divers, I care about what happens to the sea, although I would hardly describe myself as a model environmentalist. I’ve had close contact with the campaign group Greenpeace since photographing its driftnet protest in the Mediterranean several years ago. The organisation is known for its dramatic demonstrations against emotive issues such as the slaughter of whales, but it is currently trying to achieve more scientific credibility through various research programmes.
To add weight to their arguments, Greenpeace’s
anti-nuclear campaigners decided to make a detailed survey of the marine
discharges from two of the world’s biggest sources of radioactive
pollution: the plutonium-reprocessing plants at Sellafield in north-west
England and La Hague in north-west France. My job was to record the search
for the secret locations where the nuclear waste was being pumped into
the sea, and then document the team’s findings.
Using a commercial undersea search system combining laptop computer, magnetometer and differential GPS, it was relatively easy to map all the metallic objects within the area. Guided by the GPS unit, our vessel covered the search area towing the magnetometer 50m to the stern, as it logged each ‘hit’ on to a search map. The steel pipelines showed up as clearly defined lines on the computerised map. We were interested in the areas where the lines ended – the point of discharge.
Various different plants hold licences to use the pipelines
to dispose of noxious material, and they’re limited to using them
at specific times. So, we worked to schedules gleaned from insider information,
avoiding times when there was a higher risk of direct contamination. It
sounds incredible now, but when the first dives took place on the pipes
two years ago, it was just a case of ‘jump in and down you go’.
We worked on the principle that if divers working for the plant itself
could safely dive around the pipeline, then there wouldn’t (in theory)
be much of a threat to us in the short term. That idea went right out
of the window as soon as we got the first analysis results back. Suffice
to say, the radioactivity was somewhat higher than we’d anticipated
and we realised we needed to act with much greater caution.
These days, the Greenpeace team uses a small, remotely operated vehicle (ROV) to investigate the site prior to a diving session, taking a series of readings from the immediate area around a pipe. The radiation protection officer on the boat then devises a dive plan, working out maximum exposure times for individual dives, plus the cumulative effect of the whole project. The level of radiation around the pipeline dictates the equipment to be used by the divers.
Fortunately, water acts as a good radiation shield. Unfortunately, at Sellafield, the mud and sand environment does just the opposite. The risk to divers is high and necessitates a fully sealed system, with air coming from the surface via an umbilical (which also allows for communication and lighting). Dry gloves and a Kirby Morgan Superlite helmet, which seals directly on to the drysuit, complete the outfit. As you might imagine, free-swimming is virtually impossible with all this kit on, so the drysuit boots have lead soles to allow for bottom-walking – and to provide some added protection from the irradiated bottom sediment.
At the French site, La Hague, the situation is rather different. Thanks to the 14-knot currents that sweep through the area four times a day, the sea bed is composed of bare stones, with little sediment to carry radioactive contamination. The working depth is 30m (as opposed to Sellafield’s 15m), and the radiation levels are sufficiently low for divers to use conventional scuba gear, albeit with the added security of Ocean Reef and Aga masks, which offer excellent environmental protection.
La Hague’s pipe is nearly a kilometre offshore (about half a kilometre nearer than Sellafield’s), although the pipe itself is seven kilometres long and runs parallel to the headland. It discharges in the area of the highest currents around the headland, which then carry waste to the popular wrecks of Alderney, some ten miles away.
Diving protocol is always followed carefully: the first diver on the bottom takes a radiation counter fixed to the end of a long pole, which relays the signal to the radiation protection officer on the boat. As the diver approaches the area around the end of the pipe, he constantly sweeps the sea bed ahead to double-check the ROV’s findings.
Work begins in earnest once the area is declared safe (always a relative term in this field of work), with the diving team taking samples of sediment, rock and the sealife that grows right to the ends of the pipe itself. Readings are taken using an array of high-tech gadgets, including a gamma spectrometer, which can accurately identify many of the types of radioactive isotopes present. This sort of information is crucial in determining whether the material in the discharge can be legally pumped into the sea, and can tell trained nuclear physicists a great deal about what’s going on inside the power plant.
As you may imagine, Sellafield is hardly a picturesque dive site. The area has relatively little current and a flat bottom, but the artificial reef provided by the pipelines and their diffuser assemblies offers a haven for wildlife. There are fears that radiation may build up in the bodies of filter-feeding shellfish and then be distributed around a wider area by entering the food chain. Such concerns were underlined recently when it emerged that pigeons roosting at Sellafield had contaminated a local pigeon-fancier’s garden with irradiated droppings. Sellafield’s operators, British Nuclear Fuels, said there was no risk to humans, but nevertheless spent a lot of time and money removing the entire garden – pigeon-house, Tarmac and all.
While the other divers got on with the sampling tasks, my job was to photograph both the work and the sites. At Sellafield, this proved particularly challenging, with visibility averaging one metre for much of the time and my movements hampered by the weight of the helmet and the umbilical. Eventually, we got the required shots by using a combination of extreme wide-angle lenses and lengthy time exposures, together with fill-in flash. The whole experience was not dissimilar to working in British caves, an environment with which I am well acquainted. In fact, I felt quite at home and even used some of my specially designed cave-diving flashguns for some of the shots.
The atmosphere on the research boats was surprisingly easy-going, when you consider the work we were doing. During our dives off La Hague, we had several interesting encounters with the divers of COGEMA, the operators of the French plant, who were trying to disrupt our tests. On one occasion, they were accompanied by marine gendarmes, who tried to race us back to shore. We’d practically caught them in the act of tampering with our equipment, and we got photographs of the gendarmes pulling jumpers over their heads to avoid identification. The next day, the photographs hit the front pages, with the headline: ‘Greenpeace accuses COGEMA of armed robbery’.
To sample the actual discharge, a specially designed frame was installed at the end of the pipelines, carrying a sampling probe and a remote-controlled camera to capture the moment without putting divers near the undiluted waste. From the probe, a long hose pumped a sample of the discharge up to the surface, where it was collected by members of the surface crew in full chemical protection suits. No divers were in the water and non-essential personnel were removed to a second vessel away from the surface platform.
The results of the Greenpeace tests present a worrying picture. They reveal very high levels of technetium-99, a radioactive isotope released by plutonium processing. Tc-99 has a half-life of 213,000 years, making it one of the most dangerous substances ever formulated. And it’s not going to go away. We now find Tc-99 pollution as far afield as Norway, following the prevailing water currents. At the French plant, the nuclear waste passes through filtered chambers attached to the ends of the discharge pipes. The liquid waste escapes into the sea; the solid particles are stored in the chambers until COGEMA’s divers come to empty them. The level of radiation around these chambers was so high when the Greenpeace team was conducting its tests that the radiation protection officer banned all diving there.
The technical data from the sampling work is now being used by Greenpeace as it lobbies the OSPAR Commission (an annual meeting of environmental ministers from the European Commission and 15 countries in the north-east Atlantic region, including Britain and France) to call a halt to the dumping.
‘The Sellafield samples are as heavily contaminated with radioactivity as the zone around the stricken Chernobyl reactor in the Ukraine’
The sediment collected by Greenpeace was analysed for gamma radiation at the University of Bremen and the University of Wales and was found to contain a mixture of dangerous radioactive isotopes, including americium, barium, cobalt-60, europium and manganese. Americium is one of the most radiotoxic substances in the world, rated as deadly as plutonium. Cobalt-60 has the potential to contaminate any life form with which it comes into contact, causing various forms of cancers and blood poisoning.
Greenpeace argues that, by EC standards, the high levels of americium found in the sample require that it should be treated as controlled nuclear waste. According to the campaigners, the Sellafield samples are as heavily contaminated with radioactivity as the zone around the stricken Chernobyl reactor in the Ukraine.
Looking at the waters around Sellafield and La Hague, there’s little to suggest the presence of radiation. They just look like rather dull, featureless dive sites, although there is some life and you do see the odd lobster staggering around on the sea bed. (One diver swore he was followed by a one-metre-long, monster lobster, but no one else saw it.) Then you remember that, if this stretch of mud and sediment were on land, it would be classified as nuclear waste and consigned to a secure dump site. A national outcry would follow. But the nuclear waste and the lobster are out at sea where no one can see them, shielded from the public consciousness, even if the public can never be totally shielded from radiation.
Fancy lobster for supper, anyone?
© COPYRIGHT Dive International Publishing Ltd, for personal use only