Lecture 14 Flashcards
What is MOX
Fuel that can be reprocessed
What is a good tell that a country is making nuclear weapons
They are using fast breeder reactors which create plutonium as a byproduct
What are some of the most dangerous components of the cycle
reprocessed fuel
Two types of nuclear waster
Primary - ei uranium
Secondary - ei gloves used to handle uranium
What are the objectives of waste management
Mininimise the production of secondary waste
Convert them into solid (More easily confined)
Keep envioronmental impact as low as reasonably attainable
Difference between ground water and meteoric waters to waste disposal
Ground water - contains dissolved salts, pretty pregnant and so is less inclined to pick up other stuff
Meteoric waters - not salty and are more likely to carry things around
Is ground water reducing or oxidising, and is it good
Reducing, good because U is less soluble in these conditions
Why is Bentonic Clay good for containment at depth
It is a swelling clay, when it soaks up water it swells, this seals the system and ensures that nothing get through to the materials being stored (including microbes)
What is one of the negatives of using clay/something important to remember
Clay doesn’t do well with heat- it shrinks and cracks allowing things through. Additionally, if left heated for a prolonged period of time the clay with metamorphise, losing all of the properties that make it good for storage
When can boreholes be used and why are they good
For small quanitites of waste that need to be stored, if constructed at a large enough depth the holes may collapse in on themself which can be used to our advantage
Things to consider for deep storage
Tectonic Stability
Resilience to climate change
Flow of water (none preferably)
Reducing water
Thermally stable rock-water system
Strength of rock (must be able to withstand construction)
No fractures or fissures that would allow for fast pathways from repository to the surface
No significant resource potentail
3 Rock Types best suited to storage (UK)
Hard, crystalline rocks - granite, gneiss, tuffs, metamorphic basement
Sediments - clays, marls, volcanic sediments, shales
Evaporites - salt domes, bedded slats, anhydrite
3 aspects of ‘total environment’ most important to location of deep storage facility
Geological
Topogrphic
Geographical
What does a high pH environment do
reduces radionulclide solubility and reduces corrosion
What does a high surface area of backfill material for deep storage do
Increases gas despersion and maximises sorption
What are the properties of Higher Strength Rock (HSR) that make it suitable for radioactive waste disposal
Low matrix porosity and permeability
Majority of the ground water flow is confined to cracks and fissures
HLW & SF in higher strength rock - what is more important for storage the rock or the container
The container
For Lower Strength Rock (LSR) what properties make it good for radioactive waste disposal
Fine-grained and clay rich which proved low permeability
Mechanically weak meaning fractures will not be sustained
Radionuclide transport is by diffusion
For Lower Strength Rock (LSR) - how does the host rock retard the release of radioactive material
Low groundwater flux (diffusion dominated)
Sorption (increased)
Colloid filtration
HLW and SF in lower strength
sedimentary rock - what is more important for storage the rock or the container
The host rock
What makes evaporites a good rock for radioactive waste disposal
Dry
Weak - meaning cracks will not be sustained
Good thermal characteristics for the disposal of heat-producing waste
What must be considered in the use of evaporites for storage
Brine pockets
HLW and SF in evaporite rock - is the container or host rock more important
The host rock
