Antinuclear

Australian news, and some related international items

Nuclear wastes and the costs of ‘decommissioning’ dead reactors

nuke-reactor-deadNuclear decommission costs are high, and it is estimated that the decommissioning contracts over the next 15 years. will amount to $220 billion  This sum is equivalent to the creation of solar power that would replace 44 nuclear stations

Nuclear power – Game overDerek Abbott, October 2016 http://static1.1.sqspcdn.com/static/f/356082/27266889/1475068962187/NuclearPower_GameOver_DerekAbbott.pdf?token=k03ANDcymFwyMd1Uu1Y7uysGTQI=

“……  p.11 A nuclear reactor has a lifetime of roughly 40 years.4 Due to heat, high-energy neutrons, and corrosion, the metal nuclear vessel eventually cracks. Every device runs and gets hot – this sets a limit to the reliability and lifetime of any machine. Everything from a light bulb to a car engine eventually pops, and nuclear reactors are no exception. At the end of its 40-year life, a nuclear station has to be decommissioned.

The nuclear vessel itself becomes radioactive, weighs up to 500 tonnes, and has to be buried. The costs of decommissioning a reactor at today’s prices are commensurate with building them in the first place. Attempts are made by NPPs to factor in decommission cost into their economics. However, who can predict what the costs will be 40 years into the future? Typically costs blow out and the taxpayer ultimately foots the bailout.

  When an NPP comes to the end of its 40-year life, the metal reactor vessel and  core are radioactive, as they have been exposed to high-energy neutrons. If there were a vast nuclear scale-up, where would we put all these ‘glowing’ vessels? Moreover, inside the vessel, hafnium may be used as a neutron absorber, beryllium a neutron reflector, and zirconium is used for fuel rod cladding. The steel that is used to construct the vessel has to be hardened against neutron damage, and so it is typically alloyed with elements such as molybdenum, niobium, and tantalum to name a few.18

Many high performance alloys in other industries use exotic metals too, but the point is that those metals can be recycled. Rare earth metals used in the renewable industry are recyclable too. In the case of NPPs the metals become radioactive and so a scale up to 15,000 reactors in the world would be out of the question, as it would limit our elemental diversity.

Is nuclear fusion the solution? Nuclear fusion, if it ever becomes commercially useable, would be an even worse offender in terms of reduction in elemental diversity. What is not publicised is that the nuclear fusion process irreversibly consumes lithium.18 Every laptop, mobile phone, and electric car needs this coveted element. Moreover, fusion reactors end up with radioactive vessels and still require decommissioning, so the quandary of that waste remains. For these significant practical reasons, fusion is unsustainable and not the panacea it is cracked up to be.

Nuclear waste Nuclear power plants globally produce about 10,000 tonnes of spent fuel waste per annum.

When a spent fuel rod is removed from a reactor, the radiation level is so high that a one-minute dose at a metre’s distance is lethal to humans.

Each spent fuel rod generates heat and has to be stored in a pool of water at least for five to ten years to cool down. When a spent fuel pool runs out of room, the rods are then transferred into 100 tonne containers called dry casks. Each cask costs about $1 million each, and the spent fuel assemblies are transferred into the casks using costly robotic equipment to avoid human exposure. The casks are then filled with helium and are welded shut, at a cost of $500,000 each.

Dry casks are stored above ground, and the idea is that after about 50 years of further cooling the fuel can then be sent to a deep underground repository. Though, no country has yet succeeded in following through on this final costly step. A dry cask, which is stored above ground, in the meantime may corrode and leak, and transfer into a replacement cask is costly.20

Some isotopes in the spent fuel have decay half-lives over 10,000 years, and so an underground repository is the only viable final resting place for such waste.21 To repackage spent fuel from a dry cask to a special repository canister is incredibly costly. For the manufacture of canisters and provision of the equipment to perform the repackaging operation, one is looking in the vicinity of $50 billion.22

When a canister is placed in a deep repository, bentonite clay is used to delay the penetration of water and moisture. The canister eventually cracks and corrodes with time. This is accelerated due to the radiation, from the inside, and by natural bacteria23 from the outside. Once there is a leak, radioactive iodine-129 isotopes from the fuel can diffuse through rock.19 Radioactive actinides from the spent fuel are released into the biosphere through water.19 Should water ever breach the canisters, numerous chemical reactions can take place including the generation of explosive mixtures of hydrogen and oxygen.19

Why is nuclear so expensive?  The principal costs of NPPs are the capital cost of the power station and decommissioning. Then consider the enormous number of steps involved in preparing the fuel, its deployment in a highly complex nuclear station, and then the repackaging and disposal steps needed at the end of the fuel cycle. At each step there are safety risks to nuclear workers and so the complexity of the management flow snowballs due to the necessary governance structures that are put into place. As there are so many steps with attendant risks, the full end-to-end cost appears to climb.

Nuclear decommission costs are high, and it is estimated that the decommissioning contracts over the next 15 years. will amount to $220 billion  This sum is equivalent to the creation of solar power that would replace 44 nuclear stations……– Derek Abbott http://static1.1.sqspcdn.com/static/f/356082/27266889/1475068962187/NuclearPower_GameOver_DerekAbbott.pdf?token=k03ANDcymFwyMd1Uu1Y7uysGTQI=

September 30, 2016 - Posted by | Uncategorized

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