High Burn-up Radioactive Spent Fuel Dr Paul Dorfman Nuclear Consultation Group Helsinki, 8 May 2009

Rad waste – US experience Obama withdraws funding from Yucca Mountain geological rad waste dump ‘After spending billions of dollars on the Yucca Mountain Project, there are still significant questions about whether nuclear waste can be safely stored there’ – Barak Obama, Feb 2009

UK rad waste experience Current legacy - 75 billion sterling CoRWM 1 – deep disposal concept subject to intensive research and development To date very limited R & D undertaken Rhetoric of deep disposal Until then - surface storage

Prof Andy Blowers OBE, Open University, member of NIREX, member of Committee on Radioactive Waste Management 1 (CoRWM) ‘There is, as yet, no proven technical solution for the long-term management of radioactive wastes’

Rad waste – French experience 2006 - after 15 years of inconclusive research on deep underground burial, the failure to find a solution led the French parliament to authorize continuation of research on disposal and on long-term storage of the wastes

Liberalisation of the energy market in Europe Pressured Electricité de France (EDF) to become more competitive Resulted in the testing of high burn-up fuel European Pressurised water Reactor (EPR) ‘re-engineered’

EdF ‘Optimization’ study Decrease in cost could be achieved if: 15% increase in the reactor’s power Fuel was enriched to up to 4.9% uranium235 Spent fuel discharged at a burn-up of 60,000 MegaWatt days per tonne of Uranium (MWd/tU)

Burn-up rate Measure of the amount of electricity extracted from a given amount of fuel expressed in thousand megawatt days per tonne of uranium (MWd/tU)

High burn-up fuel More enriched fissile uranium used as reactor fuel to increase burn-up rate Left in the reactor for longer High burn-up spent fuel is hotter and more radioactive than conventional spent fuel Much tighter ‘safety envelope’ 16700 Students Includes visiting and exchange students (heads) and HEFP students in local colleges. Excludes students taught overseas and on external programmes. 3800 Staff 3000 full and part time, 800 casua, 96% non-academic staff live in Coventry. 3rd largest employer in Coventry area £174.5 m turnover For year ended July 2001, projected to rise to £222 m by 2004/05 Arts Centre 250,000 visits each year, 70% of audience from Coventry/Warwickshire, 67% self-generated income. £580,000 University subsidy to Arts Centre each year (not all grant)

Burn-up rate AGR burn-up MWd/tU 5,000 - 30,000 EPR burn-up MWd/tU 45,000 - 70,000

Spent fuel pools KW sq m at 5 yrs: AGR – 10.8 EPR – 17.2

US Nuclear Regulatory Commission: NUREG-1567 Standard Review Plan for Spent Fuel Dry Storage Facilities, Final Report, 2000 ‘Limited data to show that the cladding of spent fuel with burn-ups greater than 45,000 MWd/MTU will remain undamaged during the licensing period´

‘These burn-up dependent effects could potentially lead to failure of the cladding and dispersal of the fuel during transfer and handling operations’

FIAEA-TECDOC-1523 : Optimization Strategies for Cask Design and Container Loading in Long Term Spent Fuel Storage, 2006 ‘Predictions of the long term behaviour of cladding have significant uncertainties’ Fuel cladding capable of staying in the reactor for longer has been designed without regard to the long-term consequences

Hotter and more radioactive Much more radioactive isotopes in the immediate release fraction 11 x C135 C137 Changes in physical characteristics of the fuel

Risk Implications High burn up increases risk of radioactive releases as the fuel cladding gets thinner Increased risk persists throughout storage and disposal Take up much more space in any store Much bigger repository

IAEA-TECHDOC-1558: Selection of Away-From-Reactor Facilities for Spent Fuel Storage. A Guidebook., 2007 ‘Higher burn-up of fuel has a significant impact on the choice of the storage option and on the design of storage systems, due to the increased decay heat… imposing a higher cooling load to the storage system’

Higher heat Packaging must cope with higher heat transfer Needs new materials to withstand higher temperatures on components and materials Higher enrichment - spent fuels with higher gamma and neutron radiation Needs more shielding

Rad Repository Heat Output All barriers can be compromised by heat build-up from high burn up spent fuel 100 degree C temperatures at canister surface - Bentonite clay may not expand to seal containment Fractures in containers or surrounding rock – increases risk of rad leak

2006 US committee on safety of spent fuel storage Concluded that the cooling and shielding: ‘Could be compromised by a terrorist attack that partially or completely drains the spent fuel pool’ Safety and Security of Commercial Spent Nuclear Fuel Storage: Public Report (2006). US Board on Radioactive Waste

Safety Safety will depend on continuous removal of the huge thermal power of high burn-up spent fuel Additional pumps, back-up electricity supplies and backup water supplies All systems vulnerable to mechanical failure or deliberate disruption

IAEA-TECDOC-1299: Technical and economic limits to fuel burnup extension, Proceedings of a Technical Committee, San Carlos de Bariloche, Argentina, 2002 ‘Any benefits of lower electricity costs during the operation of reactors in this way will be offset by an increase in the cost of managing the spent fuel’

Safety limits High burn-up spent fuel trend has already reached the 45,000 MWd/tU limit for dual purpose storage and transportation casks

IAEA-TECDOC-1433: Remote technology applications in spent fuel management, 2005 ‘General burn-up trend is heading up to a still higher level, even though there should be a plateau level in confrontation with regulatory constraints’

Conclusions Disposal of spent fuel in deep underground repositories is unproven No experience of high burn-up fuel stored over very long periods However degradation of high burn-up fuel elements over very long storage periods is certain Retrieval, encapsulation, emplacement cannot be assumed to be possible - let alone safe

High burn-up fuel is more demanding at every stage of the nuclear cycle From reactor to cooling ponds to drying and storage in dry casks to eventual storage Increase worker and public exposure to radiation

Containment materials after cooling pond are still experimental Decades additional cooling time Spaced out in repositories - increasing ‘footprint’ Uncertainties about high burn-up spent fuel - any fixed disposal cost exposes future taxpayer to huge liabilities

Dense-packing of high burn-up spent fuel in the pools increases the likelihood of a fuel fire and meltdown should the pool water be lost in an accident or terrorist attack IAEA response to ever higher fuel burn-up is to say regulatory confrontation is required - when?

Driven by financial constraints Nuclear industry has raised the power output of proposed reactors Difficulties of managing and disposing radioactive waste are becoming insuperable Burdens of cost, effort, worker radiation dose transferred to future generations