|
WANA NEWS Newyddion CWNC Awst 2000 August CONTENTS WYLFA EXPERIMENT
“EARLY NEXT YEAR” BNFL’s experimental
programme of adapting uranium oxide fuel from the AGR’s, so that it
can be used in Magnox reactors, is prompting a wave of public hostility
in North Wales and around the Severn estuary. The so-called MAGROX
fuel destined for Wylfa and Oldbury has been described by the Nuclear
Installation Inspectorate (NII) as ‘inherently less controllable’
than Magnox fuel. Despite this, and the fact that the ‘safety case’
for its use in Calder Hall has only just been submitted to the NII,
BNFL intend to put the first MAGROX fuel into Wylfa ‘early next year’. MAGROX
fuel comprises an assembly of six AGR type fuel pins containing oxide
fuel clad in stainless steel. Each assembly would replace a Magnox
fuel element in the reactor. BNFL claim that a potential advantage
of this type of fuel is that the stainless steel fuel pin and the
oxide fuel will withstand higher temperatures than the current Magnox
fuel, thus being more fault tolerant. Environment
Agency Knew Nothing about MAGROX Because BNFL have
taken over the operation of all the Magnox stations they have to apply
to the Environment Agency for new authorisations to discharge radioactivity
from each site. Unfortunately, because BNFL didn’t tell them about their plans, there is no mention of MAGROX fuel in the 100 page consultation documents for Wylfa and Oldbury produced by the Environment Agency. This has left the whole consultation process in a mess CAMPAIGN TAKES
OFF TO SHUT WYLFA & OLDBURY After a packed
and hostile public meeting at Llangefni at which EA staff tried to
reassure the public that MAGROX was years off and would need a further
consultation on discharges, EA staff were reported to be ‘pretty fed-up’
with BNFL. At an EA public meeting near Oldbury, people were told
the truth: that there would only be one
discharge authorisation, regardless of what fuel is used in the future. Consultation responses
by letter, fax, e-mail or telephone are invited by 31 August 2000. Environment
Agency BNFL/Magnox
Consultation PO
Box 446, Bedford, MK42 0ZR Tel:
0845 6012428 Fax : 01480 483223 E-Mail:
bnfl.magnox@environment-agency.gov.uk ‘Tiny
Flaws’ Found in Wylfa Welds "With both reactors shut down, NII (Nuclear Installations Inspectorate)
asked us to carry out a set of inspections on the superheater penetrations,
or ducts," The
accessibility of any weld requiring strengthening would also be a
factor in the time taken. "A closedown of the station is not on the agenda. We want to keep
Wylfa going for another 20 years. The costs of doing the work now
will be hugely out-weighed by the extra lifetime of the station."
Cartwright
said that the major cost to BNFL Magnox Generation is the loss of
operation. "We are losing £400,000 pounds/day through lack of output." (NUCLEONICS
WEEK - June 22, 2000) Boiler
Tubes at Wylfa - WANA Comment Tubes regularly
burst at Wylfa; up to 1996 at least 109 had been simply ‘blanked off’
. The significance of a boiler weld bursting at Wylfa (or Oldbury) is far more serious.
Steam under much greater pressure than the CO2 coolant would be injected
directly into the reactor core, creating a pressure shock, putting
steam directly in contact
with hot (and increasingly unstable) graphite, and overwhelming the
safety valves. In the context of Wylfa and Oldbury where, because
of graphite weight loss, the structural integrity of the graphite
cores is in doubt, such a physical shock could displace the graphite,
blocking the coolant flow and even preventing the control rods from
shutting down the reactor. It is this hazard, and the cost of mitigating
it, that may eventually determine the fate of Wylfa.
Oldbury
Too Old Campaigning meetings
to close Oldbury started on
July 26th with the mayor of Stroud - John Marjoram agreeing to pass on the concerns expressed, about the lack of emergency
planning in the event of a severe accident, to the local authorities
involved. Jim Duffy, direct from his organisation’s successful campaign
to shut Hinkley Point A, urged people to write directly to the Chief
Inspector of Nuclear Installations, Lawrence Williams, demanding that
Oldbury be shut down rather than be used as a test bed for MAGROX
fuel.
Graphite
suffers ‘Osteoporosis’ It is known that
radiolytic corrosion of graphite affects Oldbury and Wylfa far more
severely than the other Magnox reactors. A secret CEGB report stated
in 1979 that Wylfa could only run for 20 years because of “higher
gas coolant pressure causing steel and graphite damage.”
Instead, Wylfa was kept going. Calculations were
made in 1995 that the peak weight loss of graphite at certain locations
in the reactor core at Oldbury would reach 48% by
about the turn of the century, that at Wylfa was only marginally less
severe. Failures in the graphite were predicted in the peripheral
regions at the base of the cores. Technical Background Magnox reactors,
if run long enough, lose sufficient graphite moderator (through radiolytic
corrosion) in the central part of the core to stop working. The neutrons
that emerge from the nuclear fission move much too fast (6000 miles/sec)
to sustain further fission so graphite is used to slow them down in
a series of collisions to about one mile/sec at which they are much
more likely to cause fission. If there is insufficient
graphite moderator in the core then the proportion of these slow neutrons
is reduced to the point where fission stops. Output from Olbury was
down by 10%. One response to
this is to use enriched magnox fuel so that there is more fissile
material present to catch the reduced flow of slow neutrons. Fuel
with about 14% more fissile Uranium235
is already being used in parts of the reactors at Oldbury,
and Wylfa. At Oldbury, BNFL admit that this is increasing carbon 14
and tritium discharges, but in the EA consultation for Wylfa it is
not mentioned. Magnox & Magrox - WANA
Comment: Both enriched magnox
and MAGROX are the equivalent of running an old car engine with worn
piston rings on higher grade fuel to compensate for the loss of power.
Any mechanic will confirm that this is recipe for disaster because
the rate of wear and tear will increase. The problem for BNFL is that
their old jalopies have got their bonnets welded down; they cannot
renew worn out components (such as graphite). All they can do is tinker
with the fuel. MAGROX fuel would
be substituted for magnox fuel at Wylfa and Oldbury over a five year
period. This means that low power-density uranium metal fuel (magnox),
which has a relatively low melting and ignition temperature will sit
side by side with high power-density uranium oxide (MAGROX) which
has higher ignition and melting temperature. It is the 21st
century, and the watchwords of government are openness and transparency. It may be that
BNFL has compelling answers to all our concerns, but if an experimental
fuel is to be even considered for use in civil nuclear reactors, it
is essential that BNFL publish their ‘safety case’ in full, both for
the initial testing at Calder Hall, and for Oldbury and Wylfa. Any application
to use magrox fuel at Oldbury and
Wylfa should fail because it violates the 'Safety Assessment
Principles' used by the NII: "The term safe
is also used to
qualify actions or
measures that may be taken in design, construction or operation. In these cases
it is intended to indicate a bias being introduced by the application of
that measure etc., towards a lower level of expected risk due to
the plant." BNFL claim that
MAGROX will operate at the same temperature and pressure as the existing
reactor fuel, but no-one knows how it
will behave in all the many possible fault conditions that
are increasingly likely to occur at the clapped out Olbury and Wylfa
reactors. An NII Inspector commented on BNFL’s intentions: “They can have
as many intentions as they like. We will decide.”
LLRC
2000 Speaking at the
15th Low Level Radiation & Health Conference (LLRC 2000) held
in Reading in July, Roger Clarke, chairman of the International Commission
on Radiological Protection (ICRP), and director of the NRPB outlined
the approach to radiological protection of the public put forward
by the ICRP and adopted by the UK Government. The dose limits currently
in force were set out:
It was what was
left unsaid that was puzzling. Astonishingly, Clarke omitted any mention of the ‘simplified’ controllable dose approach that he is busy promoting in the corridors of power. This does
away with the existing 1 mSv dose limit for the public, as well as the concept of
collective dose. Instead a single ‘limit’ on controllable dose is
suggested of around 20-30 mSv in a year. NIREX Transparency Policy NIREX, the nuclear
industry’s radioactive waste executive may be beginning to get the
point. Its new ‘transparency’ policy was launched in July. This states
that to achieve its mission it must be an open and transparent organisation: ·
fostering
openness as a core value ·
listening
as well as talking to people ·
making information
readily available under a Code of Practice on Access to Information ·
making key
decisions in a way that allows them to be seen and understood ·
enabling people
to have access to and influence on our future programme. Actually listening
to people is a great advance, but in case you think that this is revolution: “...we
will not release commercially confidential information if it would
prejudice to an unreasonable degree any commercial interests.” Nirex reports will
be available on the internet: http://www.nirex.co.uk
Field of dreams Tony Blair's comments to the Sort Out Sellafield campaign
would confirm his ability to fall out of touch with the public mood. He promised SOS, when a delegation visited No 10 last
week, that he would raise with the Japanese at G8 talks the need for
them to sign new reprocessing contracts with British Nuclear Fuels. The meeting was less than a week after Labour's
policy forum produced a blueprint for the next party manifesto, calling
for reprocessing to end and BNFL to move into waste management. (Guardian - Eco soundings July 26 2000) EVENTS Sept
21st Shut Oldbury - Public
Meeting, Bristol ring 01984
632109 for details Sept 23rd WANA
Meeting at Cardiff County Hall, Atlantic Wharf, 11.00am Published
by WANA PO Box 1 Llandrindod Wells LD1 5AA Tel:
01982 570362 |
