Radioactive Flashcards
A. 3 basic types of radiation
- Alpha Particles (most dangerous, cannot get thru skin, lethal if internalized
- Beta Particles (high Energy e, stopped by plywood)
- Gamma Rays (high Energy electromagnetic Radiation, m of concrete or H2O
A. Half-life
the time a radionuclide decays to a more stable form
B. Hazards of Radionuclides
- alter the chem and physical properties of the material when passed thru (DNA)
- When inhaled or ingested, some can bioaccumulate in the body where they will continue to emit radiation
C. 5 Natural Sources of Radionuclides
- Inhalation (depends on where you live)
- medical diagnosis
- comic radiation
- gamma rays from soils and Rx
- internal sources
C. Industrial Sources
NORMs may be an issue for employees
- oil and gas industry
- mineral extraction -> processing
- Forestry production
- water treatment facilities
- tunnelling + underground waste
D. radioactive waste Catelogies
- NORM (Naturally Occurring Radioactive Materials)
- radioactive wastes resulting from the nuclear fuel cycle
- atomic weapons produced from plutonium
D1. NORM
-radioactive elements found naturally in our environment or their decay products
-low concentration in earth (U and Th)
-concentrate NORM -> TENORM (technology-enhanced)
has a higher radiation levels
D2.1. The Nuclear Fuel Cycle
- Uranium mining and milling
- Refining and uranium enrichment
- Fuel fabrication
- Fuel consumption in nuclear reactors
- Fuel reprocessing
- Waste solidification
- Burial of solidified waste or reprocessing
D2.1. Uranium mining and milling
- Concentrated ore
- Large piles of waste rock and tailings, low level source of radioactivity
Fuel consumption
Produce low level radioactive (reactor wastes) which consist discarded equipment
Fuel consumption
long half life -» difficult to deal w as a waste -» takes long to become Nonhazardous to the envi
Fuel reprocessing
try to decrease the hazard of waste -> disposal (spent fuel and removes 235U & 239Pu)
Burial of solidified waste or reprocessing
final disposal options
High Level of Radioactive Waste (HLRW)
produces ionizing radiation with a strong ability to penetrate matter
Eg. spent nuclear, reactor fuel, small amount of medical isotopes
Intermediate Level (ILRW)
-requires isolation and containment beyond several hundred years
Eg. radiation therapy; used radioactive component
Low level (LLRW)
-losses all or most radiation in about 300yr
Eg. paper tower, floor sweeping, glassware…
Uranium mine and Mil waste
-waste generated by the mining and milling of uranium ore
D2.2. Levels of RW
- High level
- Intermediate level
- Low Level
- Uranium Mine and Mill Waste
E. Disposal option for RW
-based on the time frame of the isolation and include:
+interim Storage
+Long Term Storage
Long Term storage
- maintain integrity in 1000s year or much longer
- Goal: no long term monitoring required and negligible risk to the biosphere at anytime in future
Short term storage safety requirements
i) cooling mechanisms (H2O/air)
ii) shielding mechanisms. (3mof H2O, 1mof concrete)
CANOO Reactors
- duel bundles
- deemed waste after 1 year
- 30m away from an unshielded bundles
- dose 50-60 Sv/yr
- annual Rad Dose: 2mSv/yr
E1. Interim Storage of HLRW
- # of Fuel rod about 2M
- the fuel is placed in wet storage (deep water pools with both cooling and shielding process, 10yr)
- Once cooled, then transferred to dry storage
+ still radioactive
+ steel or concrete container, above grd -> air cooling
+ 1 container = 70T, life = 50yr
+ above grd dry storage
E1.2. Long term storage of HLRW - site criteria
site must be:
- geomorphically and structurally stable (area w no seismic activity, no volcanic activity, protect waste from landscape erosion)
- isolated from fractured bedrock (containment issue, if fractures, hard to clean up)
- isolated from grd H2O and grd h20 flow (no contamination to grd water)
E1.2. Long-term storage of HLRW - Disposal site considered in past
i) burital within the Antarctic ice cap
ii) Placement on the ocean floor at subduction zones
+when the barrels transferred to the subduction zone, at high P ruptured the barrels and release content to the ocean
+ if not subducted, barrels become apart of accretionary wedge
iii) Deep Geo Disposal (Terminal Storage)
+ store RW in engineered repositories within geo units where it will be isolated from zones of active grd H2O flow
+ mornitor the site for 1-2 gen and if goes well, permanent disposal of the waste
E1.2.3 Deep Geological Disposal consideration
- deep crystallize Rx (intrusive granite)
- Deep salt beds (halite)
- Deep shale beds
- thick unsaturated zones
Adv and Disad of deep salt beds
Ad: i) dry and impermeable to H2O
ii) can dissipate large amt of heal
iii) fracture that develops to self-seal
Dis: i) can dissolve to create large cavern
ii) can dissolve to create brines which corrosive
iii) salt flow - halite flow toward to the surface wehen heated
3 storage options in canadian
- deep underground storage in canadian shield
- decentralized storage at reactor sites
- centralized storage in a disposal area
* Federal gov accept combo 1 & 3 : a centralized repository deep undergrd in the canadian shield in Disposal Vaults
Adaptive Phase management
- waste will be retrievable indefinitely
2. waste will be mornitored continuously
Disposal Vault Design
- Lithology: Granite of the Canadian Shield
- Mineral Value: low,
- Depth: 500-1000m
- Storage containers: corrosion resistant, containers last for 1000yr
- GrdH2O flow: low exposure, k & K
- Buffer material: material to surround the barrels to retard grdh2o flow if it entered the repositories
- Backfill: Vaults tunnels + shift at closure
Cigar Lake Uranium Deposit
- Located in nothern Sas
- 11% of the world’s uranium deposit, 430m below the Earth’s surface (very permeable sandstone)
- High grade ore is encased in clays which formed 1.3 Byr ago
US Department of Defense Isolation Pilot Plant
- world’s 3 deepest DGR, licensed for research and production of nuclear weapons
-Location: 26km East of Carlbad New Mexico
Depth: 650
-Lithology: Halite which is 900m thick
-Material Accepted: Tranuranic low level (still Radioactive 24000yr)
