Download - Lecture 16 Mod Radioactive Waste Disposal
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
1/18
Radioactive WasteDisposal
Lecture 16
Fundamentals of Earth Resources
Environmental Considerations
L. Cathles2011
How is U burned and how is itdisposed?
The Uranium Cycle
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
2/18
Uranium Cycle
Fuel rods:
Fuel rods (pins)
3 yr in reactor 5 years cooling pond
yrs dry storage
Craig et al. (2001, fig 6.5)
Rods are ore
0 years 3 years
Hypothetical 3.3% 235U rod (pin)
1 g 235U = 13.7 bbl oil= 4.6 t coal
967 kg 238U 946 kg 238U(21 kg burned)
33 kg 235U 10 kg 235U
9 kg Pu
1500 kg metal oxides and reactorcladding so waste ~66% U
Natural ores 0.1 to 15% U
U 235/238 ratio is 10/946= 0.01Natural ratio 235/238 = 0.0071Including Pu, reactor waste 2.8 x richer
Breeder(fastneutron)
reactorsincreaseconversion
34 kg fission prods
2 kg transuranics
Know exact locationno exploration cost
Contain as much 235U as ore
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
3/18
By current law*, US plantscannot recycle and must
place 1st-cycle U-wastesafely in repositories for
10 yrs
, years
1
talRadiation
~3% initial* This may have changed now, but weare not reprocessing in the US.
10,0
00
Craig et al. (2001, fig 4.30)
T
Waste to be stored each year1. Mass loss in fission of 235U ~0.2 g/mole
E/kg-235U = mc2/ 235 = {(0.2 g/ 235 g)(1 kg)} (3x108m/s)2
= 76.5 x 1012 J/kg-235U
2. Nuclear ower lant 1000 MW = 3.15 x 1016 J / r
J of electricity
(3.15 x 1016 Je/yr )/ {(76.5 x 10
12)(0.3*)(0.75**)}
= 1.8 t 235U/yr = 52# tenr-U = 257## t U/yr
3. 3.5 m x 0.8 cm ID pin+ contains 3.34 kgenr-Ureactor consumes ~15,600 pins =313++ assemblies = 78 canisters/yr
4. Rod life 3 yrs waste canister=52 tenr-U/ 3.34x10
-3 tenr-U per pin
reactor conta ns ~ , p ns = can sters* 30% electrical conversion efficiency** 75% of 235U in rods used# enriched to 3.5% 235U## 0.0071 kg 235U per kg U in ore+ density 19 t m-2 (e.g., 3.34 kg = r2 L, pin is 100% U )++ assembly has ~50 pins, 1 transport/moving canister has 4 assemblies
0.67 t U / canister
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
4/18
Cross-checking
760 x 1012 W-hr / yr= 8.7 x 1010 W ~ 87 1 GW plants
87 1 GW plants @ 257 tU y-1= 22,400 t U/yr
22,397 t U3O8 = what US consumes per year
* 257 t U-ore/yr/1 GW power plant
www.infoimagination.org/.../global_change.html
Hypothetical High Level WasteRepository
Dispose 70,000 t U
~100,000 canisters
~78 canisters per year per 1 GW plant
~87 1000 MW plants in US today( = 6800 canisters/yr)
~waste (=100,000 can/6800 can/yr) from 100 nuclear plants
Yucca mountain baseline capacity = 70,000 t UBut performance-based capacity is likely much greater than 200,000 tThus capacity is ~50 years of current US waste production
http://neinuclearnotes.blogspot.com/2006/04/per-peterson-on-yucca-mountains.html
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
5/18
Yucca Mt RepositoryYucca Mt
70,000 t U (15 years of waste)18 burial panels each 450 x 900 m in plan 200 to 500 m deepTunnels hold 0.7 m diameter 3 m long canisters 5 m apart18 panels cover area 3 x 3 km
3x3 km
http://www.ymp.gov/uploads/images/
Water flows around tunnels
Pilot tunnel
Tunnel machine breaking surface
High LevelRepository
,
18 burial panels each 450 x 900 m in plan
200 to 500 m below surface
0.7 m diameter 3 m long canisters 5 m apart
18 anels cover area 3 x 3 km
Initial heat generation, Jo = 0.014 kW m-2
( )32.0 5.05.0
tt
o
eeJ
tJ += ,where t is in ka
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
6/18
Heating and fluid circulation
3 km
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
7/18
Maximum hot circulation
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
8/18
Is this good? Is this bad?
Look to Geology:
What has nature done?
Oklo ReactorCigar LakeOsamu Utsumi mine Brazil
Pocos de Caldas Caldera
30 km diameter
Osamu Utsumi Uranium Mine
Study to see howwaste might migrate
Uranium leaching in equatoriallocation with high rainfall
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
9/18
Simplified Evolution of Pocos de Caldas Alkaline Complex
time
Mine inbrecciapipe
Failed Waste
RepositoryAnalogue
time
Mining mineralized breccia pipe
Oxidized and ation
leached protore
30 ppm 500mmigr
40+ U ppm protore
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
10/18
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
11/18
Moles Transported
The altered band
Needed
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
12/18
Calculated ~ observed chemical changein 500 m layer for 105 kg cm-1
500
a
Calculated ~ Observed(at chlorinity of 5000 to 10,000 ppm)
Al+3
SiO
0
-5002addedtobrecci
K+
-1000
-1500
Mole
s/cm
Na+30 wt% alteration
Calculated ~ observed mineralogic
change at 105 kg cm-2
ObservedCalculated
e
ineralogicchang
Wt%m
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
13/18
How much can an intrusion convect?
Intusion
Cross sectional area ofintrusion = 2.12 km2
2,000 yrs
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
14/18
5,000 yrs
7,500 yrs
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
15/18
10,000 yrs
~ 500 kg cm-2 circulatedthou h i e at 10 ka
500 kg cm-2
fluid volume ~ 1.3 x intrusion
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
16/18
Hot circulationended by~10,000 yrs
12 km diameter intrusion can circulate 10
5
kg cm-2 through 3, 500m diameter pipes
12 km diameterintrusion
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
17/18
Complete failure of containment produces1/1000th alteration of natural system
0.03 Wt% (not 30 wt%)
(not 40 ppm)
1/1000th POCOS
Geology provides insight when assisted by quantitative analysis
-
8/3/2019 Lecture 16 Mod Radioactive Waste Disposal
18/18
References
1. Cathles, L. M., and Shea, M. E., 1992, Near-field hightemperature transport: evidence for the genesis of the Osamu
Utsumi uranium mine, Pocos de Caldas alkaline complex, Brazil,Journal of Geochemical Exploration, 45, 565-603.
2. G. J. Suppes and T. S. Storvick, Sustainable nuclear power,
Elsevier, Amsterdam, Chapter 11, Recycling and waste handlingfor spent nuclear fuel, p. 283-317.
3. http://www.phyast.pitt.edu/~blc/book/chapter11.htmp