Ground source and nuclear energy Flashcards
What are geothermal energy systems like?
Deep, high pressure and temperature
systems, typically several hundred to
1,000 m depth
What is closed system geothermal energy production?
water (and heat)trapped at depth; no or slow natural
recharge; water pumped to depththrough injection well where it heats, and then pumped (or rises) through extraction well
What is open system geothermal energy production?
water naturally recharges through groundwater flow; water escapes through hot springs, geysers and diffusion into water cycle. Often only uses extraction well only
Why is extraction balance needed for geothermal?
To avoid cooling
What is geothemrla enegry production associated with?
VOlcanic activity
Why is geothermal not really underaken in the UK?
Old geology which has majority cooled still adequate for ground heating
What is the supply roblem for geothermal energy?
Very local supply for maybe a town or city but not nationally with globa supply easily be matched by a small amount of other power generation methods
What is ground source heat like?
Shallow geothermal energy, low pressure and temperature
Why is ground source heating under utilised in the uk?
Lack of financial incentive with systems being expensive
What is ground source heat used for?
Space / domestic heating
What is the cost to run ground source heating once installed?
Low about that of an american freezer and only take 5-10 yrs to pay off
What are open system ground source heat pumps?
Exchanges heat with surface waters naturally occurring in ground
What water bodies can be used for open system groud heat pumps?
Ponds (can heat source) or aquifers
How does closed loop ground source heat pump work?
Uses boreholes (vertical systems) or shallow
trenches (horizontal systems) within unconsolidated ground (drift deposits, e.g. soils, tills, boulder clays, etc.) cycling same water in pipes. Water in closed system so not released into environment
What is cheaper installing a gas boiler or ground source heat pump?
Boiler ~3000 compared to 21000
What are tailings?
waste from uranum mining
What is the typical ore deposits % for urananium?
0.1-2%
1000-20000 ppm
Who are the biggest extractors of uranium?
Was russia until USSR dissolved then khazakstan
WHat are some events that have affected uranium price?
Financial crash increase as might have been important resource
Fukishima fall in price
Increase recently due to energy resource speculation
What are isotopes?
Same element & protons, different number of neutrons
What is the abundance of Uranium problem?
Want U235 but 238 most abundant so expensive processing to split
How are pellets used to make fuel rods?
U gas compressed to form pellets which are baked then placed in rods for power stations
What process produecs energy from nuclear?
Fission so atom spilt creating a self perpetuating cycle heating water creating stewam and driving a turbine
proc
What are the types of radioactive emission from nuclear?
Alpha (stop by paper)
Beta (stopped by aluminium)
Gamma (stopped by lead)
What is used to slow/ stop nuclear reactors?
Control rods
What probkem does the UK have with nuclear energy?
Has a backlog of waste which has not be stored or dealt with
What storage is required for Low Level Waste?
actions for the protection of people
but not so much that it requires shielding in handling or storage
Shallow burial
What proportion of waste is LLW?
Bulk of waste– 90% by volume, 1% by activity
What problemw ith LLW vaults is there? (uk example)
Produced on human timescale but what about beyond this
Uk - drigg - runout to sea in emergencies instead of land
What is the UK LLW site called?
Drigg - ~850000m3 LLW
110 hectares
What is Intermediate level waste ILW?
Higher levels of radioactivity
Includes resins, chemical sludge, metal fuel cladding and contaminated materials from reactor decommissioning
What storage has to be done for ILW?
Requires shielding
May be solidified in concrete or bitumen for disposal
Where is all high level waste stored?
In nuclear power stations
What % of radioactivty come from HLW?
95
What is the planned storage of HLW with a poor example?
Underground storage
poor example is russia leaving nuclear subs in a dry dock
What is vitrification for HLW storage?
encapsulated into molten glass and poured into stainless steel
canisters
How has the cost of storage for nuclear waste chnaged from 2015 to 2023?
Estimated cost in 2015: £85 billion
Estimated cost in 2023: £260 billion
UK spends c. £ 4.2 billion per year (2.96 from gov, 1.17 from revenue)
What are the characteristics of deep geological disposal of HLW?
250 – 1,000m underground
* Passive system
* No retrieval
* Multi-barrier system – engineered & natural barriers
What are the problems with deep geological storage of HLW?
safety, cost, public attitude, stability over
long timescales
What are the geological considerations for storage of HLW underground?
Stability – no erosion or tectonic movement
Integrity – relatively few faults, fractures, fissures
Hydrogeology – little groundwater flow
Geochemistry – sorbing minerals & reducing conditions
