|
WANA NEWS Newyddion CWNC Mehefin 2000 June CONTENTS WYLFA,
OLDBURY, TO TAKE EXPERIMENTAL FUEL While the future
of reprocessing fuel from BNFL’s Magnox reactors comes under scrutiny,
the company is continuing its
experimental programme of adapting uranium oxide fuel from the
AGR’s, so that it can be used in Magnox reactors. However, BNFL now
acknowledge that MAGROX fuel, which has been described by the
industry regulator as ‘inherently less controllable’ than Magnox
fuel, cannot be used in the steel pressure vessel Magnox reactors. This means that,
should consent be given for the fuel to be used, it will be destined
for Wylfa and Oldbury. These reactors have concrete pressure vessels,
and operate at higher pressure and slightly higher temperature
than the steel pressure vessel Magnox stations. However, there
are doubts about the future of both Wylfa and Oldbury. At Wylfa,
repairs are currently being made to boiler welds. Any attempt
to put ‘high octane’ oxide fuel in these ageing reactors will
lead to a storm of controversy. Mind the Gap! There are four
empty fuel channels in the graphite core of each reactor at Wylfa
which are reserved for TV camera access to the bottom of the core
during biennial shutdowns. These are fitted with plugs when not
in use. Two years ago a new design of plug was fitted to R2, and
a year ago these were fitted to R1. Already some of these plugs
have become dislodged, and both reactors are currently shutdown
while the plugs are replaced. WANA Comment: It is known that
between five and seven of the eight camera access locations are
affected by a mechanism which has either caused marks, or the
complete dislodgement of the plugs. This means that the graphite
degradation in Wylfa’s reactors is both active and widespread.
In 1995 the NII published its assessment of Wylfa’s long term
safety review. It was noted that the graphite of the reactor core
is oxidised by the coolant gas, and its structural strength is
gradually reduced. Nuclear Electric’s structural integrity analysis
had predicted that some cracking may have occurred, but that it
would have been limited in extent. Although the NII gave the go-ahead
for continued operation they warned: “....degradation
of graphite properties becomes more important as reactors get
older and for this reason......we will be seeking additional confidence
in the long term integrity of these complex structures.” It is not known
what further detailed analysis has been provided. What is known is that the 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 of planning
to shut down Wylfa, now 29 years old, before there is a severe
accident, BNFL is considering extending output there with fuel
for which it was not designed.
Safety
Management Audit of British Energy Generation Ltd At the end of 1999
the NII published the result of their review of British Energy, the private sector nuclear company which took over
the AGR stations and Sizewell B in 1996. It is alarming in its
implications for nuclear safety in Britain. The two component
parts of British Energy, BEG Ltd in England and BEG (UK) Ltd in
Scotland still operate as different licensees, and were preparing
to integrate many functions such as management and technical support
until late in 1998 when commercial obstacles to becoming one licensee
emerged. beggar
-v.t. (fig) ‘to
exceed the resources or abilities of’
Unfortunately,
both Beggars were by then well into ‘downsizing’. Staff reductions
had been implemented in the expectation of a reduced workload,
but the workload had not reduced. Greater reliance had been placed
on contractors, who require a great deal of supervision. As a result of
all this the NII decided
to audit the Beggars capability to discharge their safety responsibilities
in the light of the downsizing.
It was found that knowledge in some specific areas of technical
expertise had been reduced so much that only one expert person
remained, or worse: there was no-one at all. No systematic attempt
had been made to identify the minimum skill base necessary to
fulfil their responsibilities. Areas of technical expertise identified
as having insufficient specialist staff include radiation chemistry,
criticality, graphite and ‘severe accidents’. Perhaps the clearest
indication of the commercial pressures being experienced by British
Energy is their decision to abolish the post of company fire safety
officer. The NII recommend that this be reviewed, and that more
fire safety work be undertaken at each station. On top of all this
emerged a growing dependence on contractors, and the fear that
if the contractors become more ‘expert’ than the company, British Energy will have lost control of safety. beggar
-v.t. ‘to reduce
to beggary’ Investors
get Burned The desperate push
to drive down costs through ‘downsizing’ should be understood
in the context of a bleak outlook for British Energy. In May,
British Energy's profits and earnings fell by 19 and 15 per cent
respectively, and the dividend was cut by 50%. British Energy's
key problem is that it has no control over the price of electricity
- it just takes the price set by the arcane arrangements of the
pool pricing mechanism. And this has collapsed: the average price
achieved in the year to March fell by 7 per cent, but the fall
in the fourth quarter was even more severe. The looming review
of the pricing mechanism - NETA, or New Electricity Trading Arrangements
- makes it impossible to predict whether, let alone when, that
will recover. (Observer - May
14th 2000) British Energy
was also hit by problems: these caused the shutdown of two of
its key power stations, Dungeness and Heysham. That cut its output
by 9 per cent and profits will still be suffering from the shutdowns
in the current year. A cut in capacity is particularly serious
for a nuclear generator, as most of its costs are fixed and have
to be paid whether the plants are operating or not. It is doing
its best with the variable costs: slicing them by 7 per cent last
year and promising further cuts this year. If the NII prevent
further downsizing, where are the further cuts to come from? Wigner
Energy - What is it, and should we worry about it? Concern about Wigner
Energy goes almost all the way back to the beginning of the nuclear
industry in Britain. To sustain nuclear fission in a reactor the
neutrons which emerge at a speed of about 6000 miles per second
are slowed down or ‘moderated’ to about one mile per second. This
greatly increases the probability that they will produce a fission
in a further Uranium 235 nucleus. In Britain the decision was
made very early on to use graphite as the moderator. When fast
neutrons collide with the carbon atoms of the graphite two things
happen; firstly, they are slowed down by transferring their energy
to the carbon atoms of the moderator,
and secondly, part of this transferred energy is released
as heat and part of it causes a displacement of the carbon atoms
in the graphite crystal lattice. The graphite changes its shape
and ‘locks up’ some of the collision energy; this is Wigner Energy.
In 1952, a spontaneous
release of Wigner energy occurred whilst Windscale Pile No.1 was
shut down. This alarmed the
operators who then drew up a programme for the controlled release
of this energy at regular periods. It was the misreading of thermocouples
during one such ‘controlled’ release that precipitated the Windscale
fire in 1957. Initially it was thought that the graphite moderated Magnox reactors would also
require the periodic controlled release of Wigner energy. It was
stated in 1962 that Calder Hall and the other Magnox reactors
‘would require a Wigner release in five years’. In 1967 a reactor
at Chapelcross experienced a meltdown in circumstances which have
never been fully explained. The accident occurred at the time
of restarting. It was later claimed that Magnox reactors operated
at temperatures high enough to obviate the need for such measures.
There is however, a suspicion that the ‘convection cooling test’
that the CEGB wanted to carry out at Trawsfynydd in 1988 was linked
to the need to release the Wigner energy that had built up. That
test was abandoned as it bore too many similarities to the experiment
that destroyed Chernobyl two years earlier. The report into
the Windscale fire revealed that there were aspects of Wigner
energy which were ‘not clearly understood’ until after the accident.
Apprehension about Wigner energy is still evident, with NIREX
refusing to allow graphite from the Windscale piles to be placed
in its specially designed boxes on the basis that its behaviour
is still ‘not clearly understood’. The fear is that backfilling
the boxes with concrete, with its exothermal reaction, will by
warming up the graphite precipitate a fast release of Wigner energy. This violates the
criteria set by the NII for the passive safety of intermediate
level waste, one of which is that the waste should not ignite.
BNFL have yet to convince NIREX, let alone the NII that they can
safely condition the graphite from the Windscale reactors. Meanwhile, BNFL
insist that concern about Wigner energy, graphite degradation,
and ‘explosability’, are not detering them from full scale decommissioning of Magnox
reactors. No doubt we will
learn more about the practical implications from Japan, where
the Tokaimura Magnox reactor is to be dismantled Windscale
Accident - Part 2? Plans to decommission
Windscale pile 1, have been shelved because of fears that it could
catch fire again. The move has serious implications for the dismantling
of other reactors, such as Britain's ageing Magnox plants and
the damaged reactor at Chernobyl in Ukraine. In 1997, the pile's
owners, the UK Atomic Energy Authority, hired a consortium of
British Nuclear Fuels (BNFL), Rolls-Royce and Nukem of Germany
to dismantle it by 2005 for a fee of £54 million. But BNFL engineers
suspect that some of the 15 tonnes of uranium fuel left in the
pile have formed uranium hydrides, which could ignite spontaneously
in the presence of oxygen. They say such a
fire could cause a "runaway release" of the Wigner energy
trapped in the 2000 tonnes of graphite surrounding the core, which
they say would stoke the flames. The worst outcome could be a
repeat of the 1957 conflagration in which temperatures soared
to over 1200 degC. Magnox
Lifetimes to be Extended On May 23rd, the
new Chief Executive confirmed BNFL’s plans to try to keep Magnox
stations going as long as possible. Hinkley Point A is to close
immediately (see next page). The remaining steel
pressure vessel Magnox stations are to be kept going right up
to the end of their license period of 40 years, with the exception
of Calder Hall and Chapelcross which willclose at age 50.
“Continuing to
run Oldbury and Wylfa to these dates* depends upon the development
and use of Magrox fuel. Magrox is a fuel in which uranium is used
in ceramic oxide rather than metal form. A decision on the use
of Magrox fuel will be taken in around 2003. Oldbury and Wylfa
will also need to undergo a Periodic Safety Review in order to
secure operation to these dates.” “However, both
market conditions and technical issues could result in earlier
closure." “The lifetime strategy
announcement means that the Magnox reprocessing plant (B205)
at Sellafield will close once all Magnox fuel has been reprocessed.
It is expected that this will be around 2012 although
this could be later depending on throughput schedules achieved.” Current throughput
rates are poor, and Greenpeace calculate that B205 could still
be discharging up to 2018, in which case BNFL
would not meet the OSPAR reduction targets by 2020. Comment We, in the anti-nuclear
movement, believe that radioactive discharges into the Irish Sea,
from Sellafield, cause untold damage to the populations living
around the coast. The Government while not accepting the degree
of damage, have been forced to sign the OSPAR agreement which
seeks sharp reductions in discharges. By far the largest contribution
to discharges comes from
magnox reprocessing and the Calder Hall magnox reactors. BNFL’s intention
of keeping all the Magnox stations going, together with the reprocessing
that they insist is the only way of dealing with Magnox fuel,
means that discharges will continue at an unacceptably high level
until 2020. “In the meantime
BNFL will continue to work on abatement technology for Technetium
and, if successful, will reduce discharges even sooner.”
The
End of Hinkley Point A ‘Our part in its
downfall’. In January WANA
wrote to the head of the NII reminding him of the extent to which
Hinkley Point magnox reactors share the embrittlement which led
to the closure of Trawsfynydd almost nine years ago.
Lower power density at Hinkley Point, together with a thicker
reflecting layer of graphite around the reactor core had led to
the assumption that the level of radiation being felt by the steel
pressure vessel at Hinkley Point is half that which was experienced
at Trawsfynydd. The distance from
the centre of the Trawsfynydd core to the most vulnerable welds
is 9.9 metres, while at Hinkley Point it is 11.2 metres. The effect
of neutron bombardment on those welds decreases according to the
inverse square of the distance, so Hinkley Point experienced about
80% of Trawsfynydd’s neutron bombardment. At Hinkley Point,
the reactors had operated for almost 35 years, as against 26 years
at Trawsfynydd, so Hinkley
Point had suffered the same amount of embrittlement.
QED SlXTY
YEARS OF NUCLEAR HISTORY A review by Chris
Gifford The
author, Fred Roberts, helped to make Britain's first atomic bomb
in 1952. He has drawn on his inside knowledge and many other sources
to write a history of nuclear weapons and the links with nuclear
energy from the 1930's to date. He writes clearly and engagingly
about the physics, the technology and the politics. A cold recollection
of the facts is sufficient to explain to those who were misinformed
or not informed at the time and to those new to the topic just
how close to extermination we have been and how urgent the problems
of proliferation and waste management remain. How
far this matter has been away from democratic decision making
needs no emphasis. The
secrecy, sometimes necessary, and the deception that so easily
followed, still obscure the picture. That Churchill did not tell
his Deputy Prime Minister Attlee that Britain was privy to the
development of an atomic bomb was only the beginning. When Attlee
became Prime Minister he did not tell his cabinet. Parliament
was involved later mainly in voting expenditure concealed in omnibus
headings. The
elimination of nuclear weapons is not just the dream of CND supporters.
Lord Carver, formerly chief of Britain's defence staff, two former
NATO supreme commanders, John Galvin and Bernard Rogers, General
Alexander Lebed, Yeltsin's former security adviser, and more than
50 other generals and admirals from many countries concluded in
December 1996 that the end of the Cold War made international
control and the eventual elimination of nuclear weapons possible.
But it does not seem to Fred Roberts that Britain is following
their lead. SlXTY
YEARS OF NUCLEAR HlSTORY Fred Roberts, 1999, 196pp plus index,
glossary and bibliography, £12 in paperback from Jon Carpenter
Publishing 01608 811969 or from bookshops ISBN 1 897766 48 3. Environment
Agency Consultation on Magnox Stations’ Discharges Because the Magnox
power stations, operated by Magnox Electric plc, became a wholly-owned
subsidiary of BNFL since early 1998, new licenses for radioactive
discharges have to be issued. Trawsfynydd The Environment
Agency 97 page consultation document on Trawsfynydd discharge
authorisations can be summarised as saying: because Trawsfynydd
has stopped generating electricity, discharges cannot technically
be justified; therefore you don’t have to justify them, because
it wouldn’t be fair to ask. Instead BNFL are simply asked to try
to reduce discharges. Wylfa The Wylfa consultation
document doesn’t even mention the
magrox fuel that BNFL intend to use at Wylfa. As such the
document should be rejected. Demand one that considers the implications
of using rocket fuel in a clapped out reactor. (Don’t believe
the statement that magrox fuel would require a new discharge licence).
Oldbury This doesn’t mention
magrox either, but proposes to
permit an increase in the amount of gaseous tritium discharged
(perhaps related to the use of ‘enriched’ magnox fuel). The document
should be rejected on both grounds. The documents are
available online at: http://www.environment-agency.gov.uk/ourservices/consultations/magnox/index.htm 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 EVENTS July
14-16th
LLR 2000, Leighton Park, Reading - contact: Pam Vassie 0118 978 0148 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 Email:
hughrichards@gn.apc.org |
