ILW disposal in the UK

Presentation at IAEA TM-45865, September 2013

Cherry Tweed – Chief Scientific Advisor

UK Radioactive Waste

• Sources of radioactive waste– generation of electricity in nuclear power

stations– production and processing of the nuclear fuel– use of radioactive materials

• industry• medicine • research

– military nuclear programmes• Safe and appropriate management requires a

good understanding of the type and nature of the radioactive waste and materials to be managed

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• Government’s framework for managing higher activity radioactive waste through geological disposal

• NDA as implementing body committed to:– Programme of R&D– Development of RWMD into delivery

organisation– Preparation and planning for geological

disposal• Communities invited to open (without

commitment) discussions with Government– Voluntarism and partnership– Right of withdrawal

Note: Policy does not cover Scotland

Geological Disposal – UK Policy (2008)

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Schematic of ‘Single facility’ for HAW

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Baseline Timescales

Baseline Programme• First ILW waste emplacement – 2040• First HLW waste emplacement – 2075

• If added to programme, first emplacement of spent fuel from new build – 2130

• All dates are indicative. Exact timing will be agreed with host community

Illustrative geological disposal concept examples

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UK ILW/LLW Concept

Opalinus Clay Concept

WIPP Bedded Salt Concept

National LLWR Facility near Drigg

Definitions - UK

High level waste• Radioactive wastes in which the temperature may rise significantly

as a result of their radioactivity, so this factor has to be taken into account in the design of storage or disposal facilities

Intermediate-level waste• Radioactive wastes exceeding the upper activity boundaries for

LLW but which do not need heat to be taken into account in the design of storage or disposal facilities

Low-level waste• Radioactive waste having a radioactive content not exceeding 4

gigabecquerels per tonne (GBq/te) of alpha or 12 GBq/te of beta/gamma activity

UK Inventory

Pu, U and Spent Fuel are not wastes but are included in planning for geological disposal

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Material Packaged volume (m3) (2010 Baseline inventory)

HLW 6,910

ILW [1] 490,000

LLW [2] 13,800

Plutonium 7,820

Uranium 106,000

Spent Fuel 6,400

[1] Based on total volume of existing ILW stocks when packaged and future ILW arisings[2] Low level waste that cannot be disposed of at LLWR

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ILW – waste (examples)

Magnox Swarf Hulls and Ends

Legacy ponds

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Usually encapsulated in:

• Cement– BFS/OPC– PFA/OPC

Alternative processing

• Polymers (e.g. epoxy resins)• High T processing (e.g. vitrification)• Bitumen (not in UK)• Non-encapsulated (Robust shielded

containers)

ILW – conditioning process

Cutaway of cement encapsulated 500L ILW drum

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ILW – physical characteristics

Source 2010 RWI

(mass) (mass)

• ~1/3 conditioned (Packaged and or treated)

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• High activity in short-term (Cs-137, Sr-90…)

• Sharp decrease after ~ 100-1000 years,

• highly dependent on waste stream

• Activity ~order of magnitude less than HLW plot

Cs-137, Sr-90

Ni-63

Source 2010 RWI

ILW – radiological characteristics

Ni-59

Illustrative Risk Calculations – ILW concept in higher strength rock

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Some regulatory requirements

• Record keeping– Regulation require comprehensive record-keeping with duplicates

• Human intrusion – assume that human intrusion after the period of authorisation is

highly unlikely to occur– implement any practical measures that might reduce this likelihood

still further– assess the potential consequences of human intrusion after the

period of authorisation• Post-closure monitoring

– assurance of environmental safety must not depend on monitoring or surveillance

– Subsequent monitoring is not ruled out, provided it does not produce an unacceptable effect on the environmental safety case

Planned/ongoing R&D on ILW Disposal• Key radionuclides

– C-14– Uranium

• Wasteform evolution– Vitrified ILW

• Container performance– Corrosion studies

• Buffer/backfill– Long-term cement evolution

• System understanding– Nar-field component model