[ RadSafe ] Storage of spent fuel

[JGinniver at aol.com]

In a message dated 27/05/2006 02:21:48 GMT Standard Time,  
isurveyor at vianet.net.au writes:

"Nuclear  spent fuel in the USA languishes in over 
70 stirred ponds awaiting a  decision as to what 
to do with it finally.
A descision was made many years ago about what to do with sepnt nuclear  fuel 
from US nuclear power plants.  As part of a deal to end commercial  spent 
nuclear fuel reprocessing in the United States, the US government agreed  to take 
ownership of US spent nuclear fual at a set date (which I think has  passed) 
and to dispose of it in a national disposal facility.  This  facility is to be 
constructed at Yucca Mountain (if all of the licensing  requirements are 
successfully completed).  However many of the spent fuel  facilities at Nuclear 
Plants are reaching capacity and because Yucca Mountain is  not available the 
plants are having to look at alternative storage  options.  Some 
utilities/plants have successfully sued the US government  for not taking the nuclear fuel at 
the agreed date.  The option most are  adopting is to place the fuel in large 
steel, concrete or composite (steel and  concrete containers)  known as spent 
fuel flasks or casks  (as  mentioned below).  

Recent  arrivals have to be 
carefully placed so as not to be adjacent to the  
previous arrivals to avoid neutron exchange.
It is necessary to plan where to place recently discharged fuel to ensure  
that the stoarge arrangement cannot produce a nuclear excursion known as a  
criticality.  However this is simple and does not present problems for the  
operators.  In addition neutron absorbing chemicals can (and ofetn  are) be added to 
the water the fuel is stored in to make sure that a  criticality cannot 
occur. ,
 

Some  
of the longer term resident fuel elements are put 
in dry containers,  adequately spaced internally 
so as to avoid interaction.
These are the dry fuel casks mentioned above.  Some anti-nuclear  activities 
have actually campaigned to have the nuclear fuel stored this  way.  E.g. 
Robert Alvarez wrote an article in the Bulletin of Atomic  Scientists recommending 
this approach.

The  ponds have to be 
constantly stirred and cooled, so if they lose 
their  electricity supply for a protracted period, 
the spent fuel elements might  melt down and catch 
fire, contaminating the internal space inside the  
containment shield or the surrounding area if 
they are  outside.
There are two issues here.  The first is that fuel recently discharged  from 
a nuclear reactor must be stored under water and that the water must be  
circulated and cooled to remove the heat produced from the radioactive decay  
taking place inside the fuel.  The rate of heat produce is very high  immediately 
after a nuclear reactor shuts down, but the amount of heat produced  decreases 
rapidly as the radionuclides with very short half lives decay  away.  So the 
longer the fuel is stored the less heat that is produced and  the longer the 
fuel can go without cooling.  It's also important to  recognise that key safety 
systems on nuclear power plants are provided with  several diverse methods of 
electricity supply to minimise the likelyhood that a  complete loss of power 
to any safety system occurs.  In the extreme it  would probably be possible to 
cool the fuel using water supplied by fire  vehicles/appliances.
 
The second issue is that fuel cannot be rapidly transferred to dry fuel  
casks as it is still generating too much heat.  However after a period of  time in 
the cooling ponds the amount of heat being produced dies down to a point  
where the fuel can be cooled by natural circulation of air around the fuel  
storage flask/cask.  At this point it can be transferred for long term  storage in 
a cask.  The whole point of the dry fuel storage containers is  that they are 
passive and require no additional safety precautions.
 

It would  be possible to send 
the dry containers to Australia in return for the  
earned revenue from past uranium exports.

The procrastination  experienced in finding a 
final solution is to be deprecated. In the UK's  
Sellafield the external ponds are full of sludge 
and guano from  seagulls and poor records mean 
that the exact contents are  unknown.
This is a whole lot of balderdash.  In the early days of the Magnox  power 
plant programme all ponds were open to atmosphere and problems did  occur.  
However, as far as I'm aware all fuel storage ponds are enclosed to  prevent 
seagulls from floating around on the nice warm water.  The sludge  that is 
mentioned is an issue that relates to the design of the Magnox  (MAgnesium Non 
OXidising) cladding used on the first generation of Nuclear Power  Plants in the UK.  
This cladding can corrode in the cooling pond if the  water is not kept clean 
and maintained with the appropriate water  chemistry.  The Magnox cladding 
will burn readily and once buring is very  difficult to put out.  Amongst other 
reasons, it's because Magnox Fuel is  so diffficult to store, that the UK has 
a civil nuclear reprocessing  programme.  Even if the UK decided to end 
commercial reprocessing tomorrow,  it would still have to complete the reprocessing 
of the Magnox fuel from the  civil nuclear programme.
 

Tenders  are 
out to private contractors invited to quote to 
clear up the mess.  The first tranche of 
taxpayers' money to clean up the closed Magnox  
and research stations and the processing plant at 
Sellafield totals  £70 billion. 
The UK has over the last few years changed how it manages the civil nuclear  
liabilities in the UK.  Work is ongoing to put out to tender the contracts  
for the clean up and restoration of the Civil Nuclear research and re-processing 
 programmes.  It is expected that a more commercial approach will lead to  
reductions in the cost of restoring these sites.  For example the cost of  
cleaning up the sites from the reactor research programmes (currently operated  by 
the United Kingdom Atomic Energy Authority) has been reduced by over £1  
Billion in the last few years.
 
What has also not been recognised is the revenue that the UK Goverment has  
recieved from Fuel Enrichment, Fuel manufacture and Reprocessing for UK and  
foreign customers.  It also doesn't show how much of the £70 billion is to  
cover the clean up of much of the early Nuclear Weapons Programme in the  UK.  
These costs to recognise the enormous spin offs that have come from  the UK Civil 
Nuclear research programme.  For example Amersham  International that is now 
owned by GE Health Care and is one of the worlds  biggest suppliers of 
Radiopharmceuticals was once part of the UK Civil Nuclear  Programme.  There have 
been advances in many areas from technolgies to  destroy chemical weapons (the 
Silver II) process to advanced battery  technologies used in space etc.  It 
would be nice if at sometime someone  could actually review the overall cost of 
the programme including clean up and  site restoration against the benefits from 
that programme.  For example  after all the rhetoric from the anti nuclear 
groups about the UK Government  bailing out British Energy, for very little 
initial cost the Governement now  owns a stake in the company which, according to 
a report the other day, is know  worth over $6 billion, and now that the 
company is profitable the Governement is  not going to have to put nearly as much 
money towards the decomissioning  liabilities.
 

The sums  needed to 
clean up the working reactors at the end of their 
lives is  yet to be calculated, but the total bill 
exceeds the revenue from the  generated electricity by a factor of 3 or 4.
More nonsense.  There are a number of very successful projects taking  place 
around the world decommssioning Nuclear Power Plants.  In the UK, the  
prototype Advanced Gas Reactor at Windscale (part of the larger Sellafield site)  is 
one of the European Union demonstration projects for Nuclear Power Plant  
decommissioning.  It is currently below budget and ahead of time,   other European 
projects include the larger multi reactor site at Grafenwhalde(?  not sure 
about the spelling).  The projects indicate that it will cost  between £300 - 
£500 million to decommission a large Nuclear power station (which  in the case 
of the UK, generally have two reactors per power plant).  In  the UK 
Electricity Generators are currently receiving on average about £30 per  Megawatt Hour 
(this works out at 3 pence a killowatt hour).  The large  Advanced Gas Reactor 
Plants can prove about 1200 Megawatts per hour to the  national grid.  So they 
earn about £36,000 per hour, or £864,000 per day,  or £315,360,000 per year 
if they generate all year.  However UK plants  currently only have an average 
load factor (time spent generating) of about 75%  (although it should be noted 
that some reactoirs have been able to generate for  more than 650 days without 
shuting down).  So if we take the figure for the  year and multiply by 75% we 
get, £236,520,000 a year.  The plants have a  nominal lifetime of about 35 
years although work is ongoing to see if this can  be extended, so over the 
lifetime of the plant the revenue would be about  £8,278,2000,000 at todays 
prices.  As you can see this exceeds the cost of  decommissioning by a factor of 
between 16.5 and 27.5, for decomissioning to  exceed revenue by a factor of 3 or 
4, the cost would have to be £24 Billion to  £32 Billion per site.
 
These are UK figures, if anyone can do something similar for US plants I  
would be interested.  It is worth noting that Pressurised Water Reactor  Power 
Plants are comparatively simple to decomission compared to some other  types, 
and so I would expect the cost for many US plants to be a bit  lower.
 
I hope this helps, feel free to contact me for more inormation if  required.


Are the Australians really wanting to join the nuclear generation  club?

Posted by John Busby, Saturday, 27 May 2006 2:44:57  AM"