Nuclear Waste Management

• Types of nuclear wastes

• Overview of L & IL waste management

• Development of a disposal concept for HLW

• Status of disposal

(For wastes associated with electricity generation)

View of a CANDU Nuclear Power Station

Waste Types at Different Stages

Management of Mine Tailings

Waste CategoriesLow Level Waste (LLW)

• Operational wastes• Paper, rags, tools, protective clothing, etc• Short lived• Shielding not required during handling• 90% of the volume but only 1% of the radioacitivity

Intermediate Level Waste (ILW)• Operational wastes• Ion exchange resins, chemical sludges, metal fuel cladding,

filters, worn reactor parts, contaminated materials from reactor decommissioning

• 7% of the volume and 4% of the radioactivity

High Level Wastes (HLW)• Used fuel and reprocessing waste• 3% of the volume but 95% of the radioactivity

Storage of Low Level Waste(LLW are compacted or incinerated to reduce volume and stored inconcrete buildings)

Storage of Intermediate Level Waste(ILW are stored in in-ground steel containers set in concrete)

OPG’s Deep Geologic Repository for LL & ILW

OPG’s Deep Geologic Repository Project for LL and IL Waste

• Repository for long term management

• In limestone at a depth of 680 m at the Bruce nuclear site

• A 200 m thick layer of shale as a protective cap

• The low permeability limestone and shale act as multiple barriers

• At the repository horizon the pore fluid are extremely saline -indicative of no mixing with the fresh water above

• Low seismic hazard rating

• The rock formations are able to isolate and contain the LL & IL wastes for a period of more than 100,000 years.

• EA process began in 2005. Results of assessment presented to the public for discussion in 2010.

VLJ Repository for LL and IL Wastes at Olkiluoto, Finland

SFR (The Final Repository for Radioactive Operational Waste ) at Forsmark, Sweden

Nuclear Fission and CANDU Reactor

Candu Fuel Bundle

Nuclear Fuel Waste

Used fuelInside a reactor, nuclear reactions will eventually make the fuel unsuitable for producing heat, and thus the fuel is “used”.

Reprocessing Waste• Used fuel contains plutonium and uranium which could

be used to produce more energy by reprocessing. • The solidified high-level waste from reprocessing is

called the reprocessing waste.

Nuclear Fuel Cycle

Reprocessing

Pros:• Used fuel can be reprocessed into new fuel and valuable isotopes• Nuclear reactors use less than 2 % of the uranium resources• Fast reactor would potentially use 100% of the uranium• No excess build-up of accessible plutonium• It would dramatically reduce the volume of waste

Cons:• Reprocessing is uneconomical• No clear advantage for reprocessing in terms of waste volume• Reprocessing has significant impacts on safety and security• Economic, environmental, health, safety and security costs outweigh

the benefit of savings in natural uranium

Characteristics of Nuclear Fuel Waste

• Its volume is small

• It generates heat

• It is radioactive

Relative Waste Quantities(annual productions in EC)

Heat Decay of High Level Waste

Decay in Activity

How Used Fuel is Managed in Canada –Current Industry Practice

– Waste producers are responsible for interim management.

– Used fuel bundles are stored in water-filled pools, to cool and shield them until their heat and radioactivity declines significantly.

– After 7 to 10 years in water storage, used fuel bundles can be transferred to dry storage containers.

Wet Storage of Used Fuel

Dry Storage Container

Dry Storage - Outdoor

Dry Storage - Indoor

The Swedish Underground Central Interim Storage for Spent Nuclear Fuel (CLAB)

• located in close proximity to the Oskarshamnnuclear power plant (OKG).

• The storage is located in two rock vaults, the ceilings being 25–30 meters below ground level.

• The vaults are 120 meters long and each contains four storage pools and one reserve pool .

CRAB

The Need for Disposal

• Current storage practice, while safe, require continuing institutional controls.

• Methods of ensuring the continuity of controls are not considered very reliable beyond a few hundred years.

• The burden on future generation shall be minimized.

• To protect human health and the natural environment far into the future.

Disposal Options

• Transporting the waste into space– Very expensive– Probability of launch failure– Disposal on earth would still be needed

• Transmutation– Technology is not readily achievable– Disposal would still be needed

• Geological disposal

Space Shuttle Challenger Disaster

Geological Disposal

• Deep boreholes• Rock melting• Disposal at a subduction zone• Disposal at sea• Subseabed disposal• Disposal in ice sheets• Direct injection• Land based deep geologic disposal

Land-based Deep Gological Disposal

• Most countries are planning for this option.

• In Canada, three geological media warrant consideration: plutonic rock, salt, and shale.

• Canada directs most of the research on plutonic rock.

• Plutonic rock of the Canadian Shield is technically favourable and offers the greatest scope for siting.

Canadian Shield

Suitable Geologic Formations in Europe

Time Scale for Geologic Disposal

Used Fuel Disposal Concept

In-room or In-borehole Emplacement

Multi-Barrier Concept

Features of the Canadian Disposal Concept

• Multiple barriers

• Institutional controls not required

• Waste form sealed in a container which lasts 500+ years

• Disposal vault at 500 to 1000 m depth with an area of 4 square km

• The rock would protect the vault from natural disruptions and human intrusion

• In-room or borehole emplacement option

• Containers surrounded by a clay or cement based buffer

• Rooms sealed with backfill and other vault seals

• Tunnels, shafts, and boreholes would ultimately be sealed

Sweden’s & Finland’s Disposal Concept

R & D Topics for the Disposal Concept

• Disposal Container• Waste Form• Vault Seals• Geosphere• Biosphere• Total System• Assessment of Environmental Effects

R & D on Disposal Containers

Objectives:Design and test long-lasting containers and to develop models for estimating their performance.

Activities:• Studies of Corrosion of titanium, copper, nickel alloys

and a variety of steels• Welding and inspection of containers• Testing and analysis of structural performance of

container design

Disposal Container

R & D on Waste Form

Objectives:Develop models for estimating the rate of release of contaminants from a waste form.

Activities:Studies of – Processes for making glass and glass-ceramic

reprocessing waste form– Dissolution and leaching of fuel waste– Uranium ore bodies as analogues of the used fuel

Natural Analogues

• Nature has proven that geological isolation of radioactive contaminants is possible through several natural analogues.

• Examples of analogues:– Cigar Lake– Oklo

Natural Analogue (Cigar Lake)

The Cigar Lake Analogue

• The solubilities of the uranium dioxide in fuel pellets and in the ore deposit are similar.

• The uranium in the ore body has very low solubility. In fact, uranium crystals have not dissolved since they were formed 1.3 billion years ago.

• The continuing existence of this deposit demonstrates the remarkable retentive properties of the surrounding layer of clay 5 to 30 m thick.

• This gives confidence that geological systems can contain uranium oxide for very long period of time.

R & D on Vault Seals

R & D on Vault Seals

Objectives:(a) Develop methods for sealing a disposal vault.(b) Develop models for estimating the rate of transport of

contaminants through the seals.

Activities:Study sealing materials for use as• Buffer around the container• Backfill in excavated openings• Grout in open fractures in the rock• Plugs in rooms, tunnels, shafts, and boreholes

R & D on Geosphere

Objectives:Understand the behaviour of plutonic rock and associated groundwater flow systems in order to assess the performance of plutonic rock as host medium

Activities:• Studies of process that could affect contaminant

transport• Development and demonstration of methods for

characterizing and monitoring the geosphere

Groundwater Flow in the Geosphere

Discontinuities in Rock

Groundwater Flow and Long-term Safety of a Disposal Vault

The only way radioactive material could reach the biosphere is by the following sequence of groundwater transport:

• Groundwater contacts the container• The container corrodes• Groundwater contacts the waste form to release the

contaminants• Contaminants move through the vault seals• Contaminants move through the geosphere to the

biosphere

Movement of Contaminants through BarriersContainer:

– Failure only by corrosion– Copper and titanium corrode very slowly– Containers last for tens of thousands of years

Waste Form:– Dissolve extremely slowly– Many radionuclides would decay while retained in the waste

form– Contaminants move by diffusion

Vault Seals:– Movement of contaminants by diffusion in buffer– Contaminants move very slowly through backfill– Chemical reactions retard contaminant movement

Geosphere:– Disposal rooms separated from fracture zones– Dispersion in moving groundwater– Chemical reactions retard contaminant movement

The Oklo Analogue

The Oklo AnalogueGeological situation in Gabon leading to natural nuclear fission reactors1. Nuclear reactor zones2. Sandstone3. Uranium ore layer4. Granite

The Oklo Analogue

• Discovered in 1972 in an open pit uranium mine in Gabon, West Africa.

• Several spontaneous nuclear reactors operated within a rich vein of uranium ore.

• Occurred almost 2 billion years ago and continued for about 500,000 years before dying away.

• Plutonium and other radionuclides that were formed remained near their point of origin for two billion years and eventually decayed into non-radioactive elements.

• The way in which these radionuclides moved matched closely the predictions made in safety assessments of model repositories.

• This gives scientists confidence that nuclear waste can be safely disposed of in stable geologic formations.

R & D on Biosphere

Objectives:Understand the surface environment of the Canadian Shield in order to develop models for estimating the transport of contaminants through the biosphere.

Activities:– Studies of movement of contaminants in the near-

surface and surface environment– Development and demonstration of methods for

characterizing and monitoring the biosphere

R & D on Total System

Objectives:Develop and evaluate engineering conceptual designs for a disposal facility and transportation systems

Activities:• Large-scale insitu tests and demonstrations in the URL• Disposal vault designs• Designing a transportation system

URL (Underground Research Laboratory)Surface Facilities

The URL

The URL• In operation for over 25 years and decommissioned in

2010.

• Located within the Canadian Shield, in granite 2.65 billion years old.

• Dedicated to researches on geological disposal.

• Major testing levels at depths of 240 m and 420 m

• Other countries collaborated on major experiments

• URL’s lessons and findings will be applied to manage Canada’s spent nuclear fuel

• URL had played a very significant role in the CNFWMP.

Disposal Vault Design

• Hypothetical disposal vault

• Engineering conceptual design

Far Field Model for Thermomechanical Analysis

Far Field Temperature Distribution

Near Field Temperature Distribution

Near Field Thermomechanical Analysis

Very Near Field Thermomechanical Analysis

Transport of Used Fuel

Transportation Tests

R & D on Environmental Assessment

Objectives:Develop and demonstrate the methodology for evaluating the effects of used fuel disposal on human health and the natural environment.

Activities:• Identifying factors important to safety• Develop assessment models• Estimating the effects of disposal on human health and

the natural environment• Analyzing the sensitivity of the estimates to changes in

the disposal systems

Systems Variability Analysis (SYVAC)

Vault Model

Geosphere Model

Nuclide Transport from Geosphere to Biosphere

Biosphere Model

Results of Environmental Assessment

For all the times up to 10,000 years after closure :

• The estimated mean dose rate to an individual is more than 1 million times less than the dose rate specified by AECB.

• The estimated risk from inadvertent human intrusion is at least 1000 times less than the criterion.

• The estimated concentrations of contaminants in water, soil, and air are so low that there would be no significant toxicity effects.

• The dose rates to plants and animals are lower than those from background radiation.

Regulatory Guideline

Conclusions on Concept Assessment

• Implementation of the disposal concept would protect human health and the natural environment far into the future.

• The disposal concept minimizes the burden on future generations.

• Only geological disposal is a viable alternative for Canada.

• The choice of plutonic rock was appropriate.

• The concept could be implemented with readily available technology.

• The concept is adaptable to potential changes in criteria.

• The concept includes monitoring and retrievability.

• Technically suitable disposal sites exist in Canada.

Stages of Implementation

Principles of Implementation

• Safety and Environmental Protection• Voluntarism• Shared Decision Making• Openness• Fairness

Cost of Disposal• From 1978 to 1992, Canada and Ontario invested more

than $ 400 million to develop and assess the concept of disposal.

• Nuclear utilities are required to put aside a levy to provide for waste management.

• Considerable uncertainties in making cost estimates

• Cost is about 5% of the total value of the electricity generated

• 3 to 10 billion Euro for a disposal facility in Europe

• 16 to 24 billion Can$ for the Canadian disposal facility

Schedule and Cost for the Canadian Disposal Facility

Cost Estimate for Finland’s Disposal Facility

Milestones of the Canadian Programme

• In 1978 AECL was given the responsibility for doing R&D on a disposal concept. Ontario Hydro has been a partner of this R&D.

• In 1994, EIS on the concept together with supporting documents were submitted to the Federal Environmental Assessment Panel.

• In 1996, the Panel conducted a public review and acknowledged that the safety of disposal concept was adequately demonstrated.

• Following the Panel’s recommendations in 1998, the Canadian government passed the Nuclear Fuel Waste Act in 2002.

• In 2002, the Nuclear Waste Management Organization (NWMO) was established.

• The NWMO recommended the Adaptive Phased Management approach to the government in 2005 and was accepted in 2007.

• NWMO began the siting process in 2009.

Public Scrutiny & Review

Status of Sweden’s Program

Status of Finland’s Program

Status of HLW ManagementBelgium

– URL in a clay deposit established in 1984 at Mol – Construction of repository to begin in 2035

France– URL in clay and granite– Confirmation of disposal concept in 2006– Repository site to be licensed in 2015 and operated in 2025

Russia– URL in granite from 2015– Site for repository under investigation– Interim storage in operation

Germany– Interim storage in salt domes at Ahaus and Gorleben– Repository planning since 1973 – Repository may be operational at Gorleben after 2025

Status of HLW ManagementUnited Kingdom

– HLW stored at Sellafield– Nuclear Decommissioning Authority (NDA) established in 2005

– NDA is responsible for geological disposal

Japan– URL in granite since 1996– Site selection for repository underway to 2025– Repository to operate in 2035

USA– Considerable R &D on repository in tuffs at Yucca Mountain,

Nevada since 1970’s– 2002 decision that geological repository be at Yucca Mountain

was countered politically in 2009

Status of HLW Management in China

• Site selection and characterization since 1986• Tentative site: Beishan, NW Gansu province

(in Gobi Dessert)• Host rock: Granite • 2006 – 2020, basic study and site selection• URL from 2020, • Repository from 2040

Summary

• All the nuclear power producing nations opt for the option of land based deep geologic disposal of their HLW.

• The geologic host media include granite, tuff, clay and salt.

• Over 40 years of R & D• Progress varies among countries.• The safety of deep geologic disposal has been adequately

demonstrated.• Finland and Sweden are well advanced and had selected

sites for their disposal vaults.