[ RadSafe ] MoD study reveals potential impact of nuclear sub accident

[Marcel Schouwenburg]

Sunday Herald Rob Edwards Environment Editor - 06 March 2005 reports

MoD study reveals potential impact of nuclear sub accident

 http://www.sundayherald.com/print4811

THOUSANDS of people could be contaminated with radio activity in
breach of safe limits if there was an accident on a nuclear
submarine at the Faslane naval base on the Clyde, an assessment by
the Ministry of Defence (MoD) reveals.
A leaking submarine reactor could give everyone within two
kilometres a radiation dose that would increase their cancer risk.
In some scenarios the contamination could spread wider and
cause "more significant consequences", the MoD admits.
The same risks are also faced by people living near six other sites
in Scotland where nuclear submarines can berth. Three of them are
around the Clyde, and three are in the Highlands.
The MoD stresses accidents are "highly unlikely" and great care is
taken to ensure safety. But some experts accuse the MoD of playing
down the dangers, and say people up to 30km away could be
contaminated.
In response to a request from the Sunday Herald, the Royal Navy last
week released the MoD's new assessment of the accident risks at
Faslane. This Hazard Identification and Risk Evaluation, as it is
called, was conducted under the government's Radiation (Emergency
Preparedness and Public Information) Regulations (REPPIR).
For submarine reactors, the assessment "identified a number of
scenarios that could lead to an offsite release of radioactive
material". These would trigger a "radiation emergency" which could
last "several hours", the MoD concludes.
Members of the public within two kilometres of the accident could be
exposed to more than five millisieverts of radiation, it says. The
internationally recommended safety limit is one millisievert a year.
The assessment shows there are 1000 to 1600 people living within two
kilometres of nine potential accident sites at Faslane. In addition,
there are more than 3000 workers on the base at any one time.
It is "very unlikely" anyone outside the two-kilometre zone would
get a radiation dose above five millisieverts, the assessment
argues. "However a small number of low-probability scenarios have
been identified with more significant consequences."
However, the MoD does point out: "For a significant release to occur
it is necessary for there to be a plant failure followed by a breach
of multiple containment barriers."
The potential accidents analysed by the MoD include a loss of
coolant from the submarine reactor and runaway chain reactions.
Emergency measures in the event of an accident include evacuation
and advising people to take shelter to minimise radiation exposure.
People will also be asked to take iodine tablets, which can reduce
the risk of thyroid cancer.
But these plans are dismissed by independent nuclear consultant John
Large as "totally inadequate". He says that under the worst scenario
conceived by the MoD, radioactive contamination could reach high
levels as far as 30km from an accident.
If its cooling system failed, a reactor could melt down, explode and
rip open a submarine hull in 20 minutes, Large claims. "This would
be a very bad accident and it would cause chaos. The risks from a
naval reactor are significantly higher than the risks predicted for
civilian reactors. It's a whole different kettle of fish."
The navy says there are three other places around the Clyde where
nuclear submarines can berth. They are the explosives handling jetty
at Coulport on Loch Long, an anchorage known as B4 between Gourock
and Dunoon, and Loch Goil.
There are also two berths in Loch Ewe off Wester Ross. According to
the MoD, one is a buoy within two kilometres of the 150 people
living in Mellon Charles, and the other is a jetty close to 350
people in Aultbea.
The MoD assessment of the other berth – at Broadford Bay off Skye –
suggests 526 people are at risk of radioactive contamination from an
accident. The nuclear submarine, HMS Trenchant, has been moored
there since Friday, as part of an attempt to reassure locals.
However, anti-nuclear campaigners dismissed the visit as a "charm
offensive" that will not allay fears. This in turn is denied by the
navy, which points out that its nuclear monitoring team had been in
Broadford before the vessel arrived.
Navy spokesman Neil Smith warned that taking the MoD report out of
context would be misleading. "It's all about continuous improvement
and avoiding complacency. And it's against a background of a pretty
good safety record. The navy has had 60 operating years of nuclear
submarines and there hasn't been a nuclear accident."
The assessments are carried out under the radiation regulations and
made available to local authorities to help their emergency
planning, he added. "We will do anything we can to make things as
safe as possible."
The navy admits that many local residents are at risk from a minor
nuclear accident, says John Ainslie, co-ordinator of the Scottish
Campaign for Nuclear Disarmament. "But they put their heads in the
sand and refuse to prepare for a serious accident which could affect
large parts of Scotland."
Although the MoD report on Faslane concludes that a submarine
reactor accident could lead to a radiation emergency, it claims this
couldn't happen with the nuclear bombs on Trident submarines. "It is
not reasonably foreseeable that a radiation emergency can result
from this activity," it says.
---------------------------------------------

Marcel Schouwenburg
RadSafe moderator & listowner