NUCLEAR MUSINGS
Some oldies are becoming topical again:
Note: a further comment has been provided by Rudo de Ruijter, Independent researcher,
Link added in Comments below.
Note: a further comment has been provided by Rudo de Ruijter, Independent researcher,
Link added in Comments below.
“Photons and Atoms
by Mike Hohmann on Monday, March 28, 2011 at 2:53pm
OK – one swallow doesn’t make a summer, but at 12:30h on 22 March 2011,
German photovoltaic power installations fed 12.1 Gigawatt electricity into the
national grid, exceeding the combined contribution of the nine remaining
nuclear power stations together providing 12.0 Gigawatt [Sonnenseite.de
23.03.11]. Considering that current levels of PV installations are far below
possibilities, as are wind, biofuel and other CleanEnergy resources, there just
isn’t any ongoing need for nuclear energy.
Nuclear power has never been safe, and never will be, it appears – their
risks just cannot be insured. The Times [09.09.09.] reports a notional Public
Liability premium cover requirement of £620 million per power station, any
excess falling on the taxpayer in addition to risks from waste storage and
health and life losses. The world’s largest re-insurance company – Munich Re –
is reported [oekonews.at / sonnenseite.de, 23.03.11] to have declared that it
is impossible to say how high an insurance premium should be in the absence of
state guarantees, because there is no known modelling method on which to
base a risk assessment.
Compare this to the £5million Public Liability Insurance being asked
from residents who want to hold a Street Party on the occasion of the forthcoming
Royal Wedding.......”
Or as Douglas Adams put it:
“The major
difference between a thing that might go wrong and a thing that cannot possibly
go wrong is that when a thing that cannot possibly go wrong goes wrong it
usually turns out to be impossible to get at and repair.”
But even if the
actual nuclear powered steam engines work as they should, unresolved problems
remain for which our grandchildren – and theirs in turn – are unlikely to
forgive us. I enclose copy of a
translation of a memorandum received over a year ago:
ooo000ooo
Translation of a memorandum received from Franz Eder dated 21 April
2011
Notes on occasion of the nuclear disaster in Japan, and
considering general problems with nuclear power
by Franz Eder 21.4.2011
“Die ich rief, die
Geister,
|
From the spirits
that I called,
|
werd'ich nun nicht
los.
|
Master, now
deliver me!”
|
Goethe, The
Sorcerer’s Apprentice
|
-1-
The Dangers of Nuclear Accidents
To start with, I would
like to make clear that I write these notes from a layman’s point of view for
use by other non-specialists like me; a nuclear physicist might well look
askance at them. I am convinced,
however, from talking to many other laymen like me that very little about these
matters is generally known – which is why I hope these notes may be helpful.
These days we hear and talk much about the “Sustainability”
of actions and processes, for example
- Renewable resources must
NOT be used faster than they grow or can be regenerated
- NON-renewable resources
(e.g. oil, gas) may be used only to the extent that renewable resources
can NOT be made available.
These requirements
for sustainability, while enshrined in law, so far exist only on paper.
The only real example in practice of enduring
“Sustainability” is illustrated by the current nuclear disaster in Japan, with
its aftermath ‘sustainably’ affecting men, women, children, animals, plants,
air and ocean – for generations to come.
[remember Chernobyl in 1986; full list of nuclear disasters
and their aftermaths at http://www.spiegel.de/international/world/0,1518,756369,00.html#ref=nlint
].
A few technical details:
- To ‘switch off’ an atomic
power station, or to take it off-line in more technical parlance, requires
the careful gradual insertion of control rods among the fuel rods in order
to slow down the chain reaction of the nuclear fission process.
- During this process, the
first 20 to 30 hours are extremely critical because the heat produced is
no longer withdrawn by steam for power generation and the fuel rods get
hotter. An increased cooling effort
is required, not only with water but also with special coolants to keep
the fission process within manageable limits.
- After this initial period
continual cooling of the reactor is a more normal routine. [the working temperature
of a nuclear reactor is around 800ºC.
It is claimed that the switch-off process can be routinely
mastered].
- This requires some remarks
about the Chernobyl accident. The
operators of the plant wanted to simulate an emergency, disconnected
several safety systems in order to test what might happen and how one
would need to react.
- During this emergency
exercise, which also involved temporary reduction in cooling systems, the
reactor over-heated to an extent that the control rods were no longer able
to slow down the reaction and the rated heat output was exceeded by a
factor 100.
- This emergency exercise
was carried out over several days so that changing teams of operators were
put to test in a shift system.
The result was an enormous increase of temperature inside
the reactor, finally resulting in an explosion of the whole plant which blew
off the 1000t heavy lid of the reactor allowing an unhindered release of
radioactivity affecting wide parts of Europe, contaminating grass, mushrooms,
milk etc.
In short, nuclear power generation is a very risky business.
- 2 -
The Dangers from Spent Fuel Rods
- The fuel rods in nuclear
reactors generally last for five years producing power in accordance with
their design specification through nuclear fission, i.e. they boil water
which powers steam turbines which in turn drive generators which finally
produce the actual electricity.
- At the end of their useful
life the spent fuel rods are retrieved by robots from the reaction vessel
and must be stored in cooling basins within the reactor building because
of their high temperature of about 800ºC.
The on-site cooling period varies between one and five years. Once cooled, these spent fuel rods were
then (until 2005) transported to La Hague in France or to Sellafield in
the UK to be reprocessed, i.e. 1-5% of the residual uranium are chemically
extracted for use in new fuel rods.
Since 2005/6 it is illegal
in Germany to send spent fuel rods for reprocessing, so that spent fuel
rods have to be directly transported into interim storage facilities, e.g.
Gorleben, where they need to be stored for an interim period 40 years before
they can be transferred into final storage depots – which, however, do not yet
exist.
- To stay briefly with
reprocessing: the remaining nuclear
waste (95-99% of spent fuel rods) remains highly radioactive and is fused
with borate glass at a temperature of 1100ºC and poured into stainless
steel tubes and sealed by welding; these cocoons have a diameter of 40cm
and are 1.40m long.
- The waste products in a
fuel rod represent about 90-99%, the remaining 1-10% yield during
reprocessing uranium and plutonium for re-use as fuel rods.
The CASTOR Transport
Container
The containers for transporting spent fuel rods or cocoons
are known as Castor Containers and are used to convey reprocessed fuel rods and
the highly radioactive waste from reprocessing plants in La Hague or Sellafield
to intermediate storage at Gorleben.
The technical details of Castor Containers:
Length: ~
6.00m
Width: ~
2.50m
Weight: ~
120t
Load capacity: ~ 10t ( that is 50-70 spent fuel
rods, or 28 glass cocoons).
Cost €
1.5million
The Federal Republic of Germany is bound by contracts to
take back all nuclear waste that arose from reprocessing spent fuel rods before
2005; that means that transports from
France are necessary until the end of 2011 and those from the UK are programmed
to continue for between 2014 to 2017.
The contents of Castors – whether fuel rods or glass cocoons
– produce considerable heat, in the order of 400ºC, so that Castors have
cooling ribs all over to help dissipate that heat. In addition, the radiation must be constantly
monitored because the 40cm thick envelope does not fully prevent the escape of
radioactivity.
Post-shutdown
Residual Heat
When a nuclear reactor is shut down the radioactive decay of
fission products continues to emit heat.
The power of this residual heat is about 10% of the thermal power of the
reactor when under full load. Should any
cooling systems necessary to dissipate this residual heat stop functioning for
any reason then rising temperatures may lead to hydrogen explosions and lastly
to reactor melt-down – as happened in Japan.
This process will happen with spent fuel rods which are
similarly subject to this residual heat at 10% of design power and must,
therefore, be cooled in on-site cooling basins from 800ºC down to 400ºC. This takes about 1-5 years; only then is it possible to transport them.
Should anything disrupt the cooling arrangements during this
period of residual heat dissipation, then even these spent fuel rods can
produce enough heat from continuing nuclear chain reactions to lead to
explosions and meltdown similar as might happen to the reactor itself.
The residual heat
problem was my real reason for writing these notes because I think I am not the
only one unaware of the big risks still latent in burnt-out fuel rods even
after the have become useless for energy generation.
Perhaps we may better
understand now why these long storage times for up to five years’ cooling
within power stations followed by 40 further years in interim storage are
necessary. Only then is it possible to
send these nuclear waste products to yet non-existent final depositories where
they continue to dissipate heat and radiation. These final depositories are
unacceptable to the public anywhere and remain the unresolved problem of the
nuclear power industry.
I hope my brief notes
may help to understand immediate and long-term dangers from nuclear power
generation so that we know that no effort should be spared to rid ourselves
from this menace. Nothing I wrote is
“directly copied from any nuclear scientist” but is based on my understanding
of articles in Wikipedia and www.Kerntechik.de.
Writing as a layman, may I be forgiven for any errors..
Issues with
Radioactive Waste:
- A nuclear power station
with an output of 1,300MWp (the size of recent German power stations)
produces about 50m3 per
year of low heat producing radioactive waste,
- During reprocessing, a
further 10m3 of low heat
producing radioactive waste arise
- In addition app. 3m3 highly radioactive fission
products need to be dealt with
- German nuclear power
stations produce 450t/year of highly radioactive spent fuel rods
- Worldwide, 12,000t/year of
highly radioactive waste are produced;
by the end of 2010 a total of 800,000t has accrued, of which
70,000t in the US alone.
- In Germany, the costs for
dealing with nuclear waste are exempt from the general principle of the
originator being liable for safe removal or storage. The result is that
the taxpayer instead has to bear these costs, e.g. € 3million for nuclear
waste transports alone, not to mention any other measures for dealing with
the sheer never-ending problems with nuclear waste.
Some issues regarding
nuclear waste from French and UK Reprocessing Plants:
Abbreviations used:
NPS =
nuclear power station
RPP =
reprocessing plant
FR =
fuel rod
HAW =
highly active waste
CC =
Castor container
SD =
storage depot
Cocoon =
stainless steel container for highly radioactive waste fused within borate
glass
Nuclides =
unstable elements subject to radioactive decay
Radioactive Waste
from RPPs in France and the UK
The borate glass, or more correctly, the HAW cocoons are
stored for two years within the confines of RPPs before they are returned to
Germany. HAW cocoons generate heat so
that before any final storage can be arranged they must be allowed to cool
sufficiently in interim depots so that the rock caverns for eventual final
storage are not overstressed.
The interim storage time for French cocoons is 30-40 years,
cocoons from the Uk need to be stored for 40-50 years.
Each spent FR results in 0.6 to 0.9 cocoons, so that
radioactive waste from reprocessing results in 2,850 cocoons from France and
700 cocoons from the UK which must be transported back to Germany.
One Castor container can hold a maximum of 28 cocoons, so
that around 130 CCs are needed to transport these ‘hot potatoes’ back to Germany.
Some more interesting numbers: the average temperature of HAW cocoons is
about 400ºC when leaving La Hague. The
maximum allowed safe temperature is 510ºC, but from temperatures above 500ºC
the vitreous structure of cocooned waste can already deteriorate and crack,
resulting in increased atomic radiation – a risk about which no further details
are made public. Above 600ºC the safe
containment of radioactive material within the glass matrix can no longer be
maintained.
If you followed me so
far, I had in mind to elaborate further on ‘cocoons’, but that led me deeper
into the whole nuclear mire than I had imagined. One amongst laymen, I had
assumed that radioactive waste once fused within glass would be forever safely
‘locked behind bars’ – but no such luck.
Radiation Intensity
of Cocoons
From here on I shall
be dealing with some numbers whose significance, I must confess, I don’t fully
grasp, but whose consequences are so momentous that I wish, at least, to put them into perspective.
The nuclear wastes fused with glass inside cocoons are
classified as highly radioactive, containing an unimaginably high number of
unstable ‘nuclides’ which decay with varying lengths of half-lives. During
decay they release particles (alpha and beta decay) as well as electromagnetic
radiation (gamma rays). It is the
release of particles that is responsible for creating heat through friction
with other atoms.
This is particularly important for the eventual final
storage; highly active waste (HAW) is
also classified as ‘thermo-active waste’, usually known as HAW Cocoon.
HAW still contains 98-99% of the nuclear power present in
the original fuel rods, for us laymen that’s still the same potential
power. This residual energy arises from
the fission products in the reactor (mainly gamma and beta radiation) and
trans-uranium elements created by alpha
particles.
At this point in my
learning curve it was essential to understand the reasons for the high
resultant heat; to remind ourselves, the
cocoons still have a temperature of 400ºC after two years of storage in the
RPPs and must be transported at this temperature.
Radiation Dangers
from Cocoons
The radiation potential of HAW cocoons is, for laymen like
us, unimaginably high. The half-life
of the remaining nuclides can be as high as two million years. Particles with short or medium long
half-lives, e.g. caesium 137 gamma rays, are responsible for the high radiation
doses during transport and interim storage, while the longer-lived nuclides,
like alpha radiation from Neptunium 237, are the cause for the long-term safety
problems at final containment depots.
Comparison of Risks
According specification, HAW cocoons from France can have
extremely high radiation values from
- caesium 137,
- strontium
90, and
-
plutonium.
Staying with caesium, this means that with 28 cocoons in one
Castor container it has the same radiation potential as a CASTOR V NPS containing 10t of fuel rods.
At this point in the discussion, comparisons may be more
useful than numbers, for example:
- For a German NPS with an
output of 1,300MW the total radioactive ‘inventory’ has only a marginally
higher radioactive content than a SINGLE
Castor container.
- The content of a single HAW CC is the approximate equivalent of
20% of the nuclear inventory released during the Chernobyl accident.
- The Gorleben storage depot
for cocoons is licenced to contain the radioactive inventory of 2,000
HAW CCs (that’s 56,000 cocoons).
To end these comparisons, a last example of the immense
risks from this radiation load:
- A single unshielded HAW cocoon has a surface radiation power which
is lethal for humans within 60 seconds at a distance of 1.00m.
These examples alone should convince anyone that living with
this “witches’ brew” should be avoided.
The data for RPPs and
cocoons are taken from an essay by Wolfgang Neumann, physicist at The Ecology
Group, Hanover.
I hope these notes
have thrown some light – if not shadows
– on the cycle of nuclear power generation, and I should be pleased to receive
any comments or corrections.
Franz Eder
Bruckmühl
21.4.2011”
ooo000ooo
“Sellafield-2 will produce 7.5 tons of
plutonium every year. 1.5 kilogram of
plutonium will make a nuclear bomb.
Sellafield-2 will release the same amount
of radioactivity into the environment as Chernobyl every 4.5 years. One of
these radioactive substances, krypton-85, will cause death and skin cancer”
The Real Costs
of Nuclear Electricity
“It is hardly acceptable
on moral grounds to assess the costs of possible consequences of a nuclear radiation
catastrophe for life and limb of millions of people as well as the
establishment of nuclear contaminated no-go areas in densely populated areas, in
financial terms in order to arrive at a cost benefit calculation.”[1] The same source quotes an estimated public
liability premium of Euro 287billion to cover the likely costs of Euro 5trillion
from a nuclear meltdown; nuclear electricity
plainly is beyond imaginable costs..
The movie 4th
Revolution [2] quotes the external costs of nuclear electricity at Euro 2.70/kWh.
Compare this with the
current costs of solar PV of Euro 0.14 and onshore wind of Euro 0.07 per kWh (unsubsidised).[3]
[1] http://www.wirtschaftsdienst.eu/archiv/jahr/2011/4/2545/?PHPSESSID=42703cfeae86f37d15b7768ba4eedce9
Rudo de Ruijter, Independent researcher, has provided a link to his article
ReplyDelete"Raid on Nuclear Fuel Market", to be found at
http://www.courtfool.info/en_Raid_on_Nuclear_Fuel_Market.htm