lectures on nuclear technology and environment(2008 07@the university of tokyo)
DESCRIPTION
TRANSCRIPT
人間環境デザインスタジオHuman Environmental Design Studio
1:00-4:15 pmJune 24, July 1, July 8, and July 15, 2008
atGraduate School of Frontier Sciences
The University of Tokyo
Joonhong AhnDepartment of Nuclear Engineering
University of California, Berkeley
Who am I?• Professor, Dept. of Nuclear Engineering, UC Berkeley
• BS, NE, Todai, 1981 (Prof. Iwata)• MS, NE, Todai, 1983 (Prof. Kiyose/Suzuki)• PhD, NE UCB, 1988 (Prof. Pigford)• D. Eng, NE, Todai, 1989 (Prof. Suzuki)• JSPS Junior fellow, 1988-1990• Lecturer, Todai, 1990-1993 • Assoc. Prof., Tokai U., 1993-1995• UCB since 1995
• third generation Japan-born Korean
Objective of the class
• This series of lectures introduces – fundamental technical facts about
environmental issues with nuclear power utilization.
– discussions on long-term environmental safety of geologic disposal, including
• How engineers have established technologies for securing and assessing long-term safety, and
• How societal agreement has (not?) been developed, particularly in US.
Syllabus• June 24 – Technical basis for nuclear environmental
issues– Nuclear fuel cycle and the environment– Geologic disposal
• July 1 – Performance assessment of geologic disposal– Performance assessment– Can the environmental impact be reduced by recycling?
• July 8 – Societal and ethical issues of geologic disposal– Development of societal agreement for geologic disposal– Ethics in/of geologic disposal
• July 15 – International aspects of nuclear power utilization– (Introductory summary for nuclear activities in India)– (Comparative discussions among Japan, US, and India)
Format of class• Prerequisites
– Fundamental knowledge about nuclear fission– Fundamental knowledge about chemical reactions
• Each topic consists of:– ~ 1 hour lecture for summarizing basic facts – discussion
• Reading materials/text books:– Relevant reading materials will be given to
supplement class discussions upon request.• Grading:
– ?? (Ask Prof. Iwata!)
Do you know these?• Isotope• Half life, decay constant• Radioactivity• Uranium, plutonium• E=mc2
• Fission• Fission products• Thermal neutrons• Fast neutrons• Cross sections• Light-water reactors
• McCabe Thiele diagram• PUREX• TBP• Retardation factor• Darcy’s law• Aquifer• Biosphere
Week 1 (6/24):Technical basis for nuclear
environmental issues
Nuclear fuel cycle and the environmentGeologic disposal
Nuclear fuel cycle and
the environment
Fuel consumption and waste generation from various electricity generation sources for 1GWe.year
Fuel consumption [ton] Waste generation [ton] CO2 5,000,000
Crude oil 1,400,000 SO2 40,000NOx 25,000dust, particles, ashes 25,000CO2 6,000,000
Coal 2,200,000 SO2 120,000NOx 25,000dust, particles, ashes 300,000(Uranium) (28.8)
Nuclear 30 (Plutonium) (0.3)Fission products 0.9
Comparison with Fossil Fuels
C12 + O2 → C12 O2 + 4 eV
per atom [eV] per gram [W•hr]
Carbon ~ 4 ~ 10Uranium ~ 2E8 ~ 2E7
0n1
0n1
y
92U235
92U235
92U23894Pu239
x
200MeV
2.43
Nuclear Fission
Chemical reaction
Uranium• Uranium is mined as U3O8.• It is composed of;
– 99.3% by weight 92U238
– 0.7% by weight 92U235
• 92U235 is fissionable with slow neutrons, i.e., thermally fissile.
Light-water reactors (Current fleet of commercial reactors)
• 92U238 is fissionable with only fast neutrons.– However, 92U238 is a “fertile” isotope, generating
94Pu239 (thermally fissile).Reprocessing and recycle of spent U fuel
Uranium Ores
Open Cast Mining
Uranium mining technologiesUranium mining technologiesUnderground Mining
In-Situ Leach (ISL) Mining
Production per Method (%) as in 2003(total 35 772 t U)
Deepunderground
mining
Co-/By-product
ISL mining
Open pitmining
20%
28%
11%
41%
Uranium Resources (million ton)Known Conventional & Identified Resources
Undiscovered Resources
Cost range(US$/kgU)
Reasonably AssumedResources (RAR)
Inferred Prognosticated
Speculative
< 80 2.64 1.16 1.7080 – 130 0.66 0.28 0.82>130 4.56Unassigned 2.98Subtotal 3.30 1.44 2.52 7.54Total 4.74 10.06
14.80IAEA Red Book 2005
Global Uranium Resources & ProductionGlobal Uranium Resources & ProductionUranium Production
(total 41.360 tU in 2005)
Canada28%
Australia22%Kazakhstan
10%
Niger8%
Other9%
USA2%
Russian Federation
8%
Namibia7%
Uzbekistan6%
Identified (RAR+Inferred) Uranium Resources below $130 /kgU (total=4 743 000 t in 2005)
Australia24%
Kazakhstan17%
Canada9%
USA7%
Namibia6%
Russian Federation
4%
Uzbekistan2%
Niger5%
Brazil6%
Other20%
Kazakhstan’s large resource is planned to be utilized by in-situ leaching.
Nuclear Fuel Cycle and Waste GenerationLLW 1,000 drums
26 ton U0.95 ton FP0.27 ton Ac
0.24 ton Pu
TRU/LLW
< 0.26 ton U0.95 ton FP0.27 ton Ac
~ 1 ton URa, ThMill tailings U7%
Th-230 100%, Ra 98%Airborne Rn
0.2% U3O8= 181 ton U
167 ton
26 ton
100,000ton ore
165 ton(0.3%U-235)
~ 0.5 ton U
27.5 ton
27.3 ton
~0.2 ton U
1 GWe, LWR, 1 yearReprocessing schemeThermal efficiency 0.325Capacity factor 0.8
Yellow cake
Mill tailings pile in Utah
Uranium enrichment
uranium mines, enrichment plants, and Yucca mountain repository
Portsmouth, OH
Oak Ridge, TN
Parducah, KY
Yucca Mountain Repository
Presently, 704,000 tons of DU stored in UF6 form in the US.
Nuclear Fuel Cycle and Waste GenerationLLW 1,000 drums
26 ton U0.95 ton FP0.27 ton Ac
0.24 ton Pu
TRU/LLW
< 0.26 ton U0.95 ton FP0.27 ton Ac
~ 1 ton URa, ThMill tailings U7%
Th-230 100%, Ra 98%Airborne Rn
0.2% U3O8= 181 ton U
167 ton
26 ton
100,000ton ore
165 ton(0.3%U-235)
~ 0.5 ton U
27.5 ton
27.3 ton
~0.2 ton U
1 GWe, LWR, 1 yearReprocessing schemeThermal efficiency 0.325Capacity factor 0.8
Interim Storage of Spent Fuel
Spent Fuel Accumulation in US
YMR capacity September 2007
Repository Availability in US• Repository capacity, 63,000 ton SF.• Assume that:
– The present annual electricity generation (G = 70 GWy/year) is maintained (no growth).
– The spent fuel generation per GWy is calculated byW = 38,000 ton SF/1420 GWy = 27 ton/ GWy.
– The electricity generation C supported by this capacity:C = 63000/27=2330 GWy
• The YM repository availability is obtained as – C/G = 2330/70 = 33 years.
• 3 YM repositories will be necessary for one century.
Reprocessing of Spent Nuclear Fuel
Step 1: Decladding and Chopping
Step 2: Dissolution into HNO3
Step 3: Extraction of U and Puby Tri Butyl Phosphate(TBP)
Step 4: Pu Recovery from TBPto Aqueous phase
Treatment of spent fuel with reprocessing
HighLevelWaste
COMMERCIAL SPENT URANIUM OXIDE FUEL REPROCESSING PLANTS IN OPERATION AND UNDER CONSTRUCTION IN THE WORLD
Country / Company Facility / Location Fuel Type Capacity
(tHM/year)
France, COGEMA UP2 and UP3, La Hague LWR 1700
UK, BNFL Thorp, Sellafield LWR, AGR 1200
UK, BNFL B205 Magnox Magnox GCR 1500
Russian Federation, MinatomRT-1 / Tcheliabinsk-65
Mayak 400
VVER 400
Japan, JNC Tokai-Mura LWR, ATR 90
Japan, JNFL Rokkasho-Mura
(under construction)
LWR 800
India, BARC PREFRE-1, Tarapur
PREFRE-2, Kalpakkam
PHWR PHWR
100 100
China, CNNC Diowopu (Ganzu) LWR 25-50
Storage of High-Level Waste solidified with Borosilicate Glass
Storage pit at R7 COGEMA (France)
• Fission Products– Sr-90, Cs-137, Cs-135, I-
129, Tc-99, ...
• Trans-uranic + U, and their decay daughters– Am-243, Am-241, Np-237,
Pu-239, Pu-240, Pu-242, Cm-245, Cm-244, ...
• Activated materials– H-3, C-14, Zr-95, Ni-63,
Fe-55, Co-60, ...
Radioactivity of HLW
Geologic disposal
Yucca Mountain
• Location: 100 miles NW of Las Vegas in Nye County
• Withdrawal Area: 230 sq. miles (150,000 acres)
• Distance: 14 miles from nearest year-round population
1 acre = 4,046.86 m2 = 1,224坪
HUMBOLDTCOUNTY
PERSHINGCOUNTY
ELKOCOUNTY
WHITE PINECOUNTY
NYECOUNTY
LAN
DER
CO
UN
TY
EUR
EKA
CO
UN
TY
CHURCHILLCOUNTY
WA
SHO
EC
OU
NTY
MINERALCOUNTY
STOREYLYON
ESMERALDACOUNTY LINCOLN
COUNTY
CLARKCOUNTY
LASVEGAS
INYO COUNTYCALIFORNIA
NELLISAIR FORCE
RANGE
NVTESTSITE
YUCCAMOUNTAIN
CARSON CITY
DOUGLAS
Yucca Mountain• Geology:
Composed of ash tuff deposited 10 million years ago
• Elevation: 4950 ft. at crest
• Climate: receives less than 7.5 inches rain annually
• Resources: none of commercial value
Yucca Mountain Repository
63,000 ton HM for CSNF7,000 ton HM for Defense wastes
4,500 ton HM equivalent HLW2,500 ton HM SNF (15 categories)
Yucca Mountain Repository Design
Three Types of Waste Packages
Number of packages
CSNF 7886
Co-disp 3564
Naval 300DW
Program Key Milestones• Design for License Application
– Completed December 1, 2007• License Support Network Certification
– October 19, 2007 (two months earlier than schedule)– Recertification: June 3, 2008
• Supplemental EIS– Draft issued October 2007/hearings completed
• License Application– Submitted to NRC on June 3, 2008– Submittal included 208 references– Will be “docketed” within 90 days (8/31) from the submittal
date– Review by NRC will be completed within 3 years (2011).
Program Key Milestones (cont’d)
• Start Nevada Rail Construction - October 2009– Delayed - Inadequate funding to proceed with design
• YM Construction Authorization - September 2011– Depends on NRC decision
• Operating License Submittal - March 2013– Predicated on funding and construction schedule
• Rail Line Operational - June 2014– 2016 is achievable only if adequate funding is provided
• Begin Receipt - March 2017 (Best Achievable Date)– Currently under evaluation due to FY 07 and 08 actual funding
shortfalls and expected near term funding limitations– Firm date cannot be set until funding issue resolved
Waste Isolation Pilot Plant (WIPP), Carlsbad, NM
• The world's first underground repository licensed to permanently dispose of transuranic (TRU) wasteleft from the research and production of nuclear weapons.
• After more than 20 years of scientific study, public input, and regulatory struggles, WIPP began operations on March 26, 1999.
• Located in the remote ChihuahuanDesert of Southeastern New Mexico
• disposal rooms mined 2,150 feet underground in a 2,000-foot thick salt formation that has been stable for more than 200 million years.
• Transuranic waste is currently stored at 23 locations nationwide.
• Over a 35 year period, WIPP is expected to receive about 19,000 shipments.
• undertaken by DOE• Waste from defense activities• Exempted from NRC regulation (EPA Certificate)• Bedded salt• 176,000 m3 Contact-Handled (CH)TRU, • 71,000 m3 Remote-Handled (RH)TRU
$ 410,000 per TRUPACT-II
Waste package located in WIPP
Inside the package
Geologic Disposal Concept in Sweden/Finland
• water-saturated granite
• LWR spent fuel• copper canister
(lined with titanium)• bentonite buffer
HLW Geologic Disposal Concept in Japan
Tunnel typewater-saturated graniteVitrified wastecarbon-steel overpackbentonite buffer
Functional requirements for Geologic Disposal(OECD, 1989)
• The goal of final disposal is to protect human health and the environment and to limit the burdens on future generations.
• The waste must not be released to the biosphere at concentrations deemed to present an unacceptable hazard.– Health risks and effects on the environment from waste disposal, at any
time in the future, shall be low and not greater than would be acceptable today. The judgment of the acceptability of a disposal option shall be based on radiological impacts irrespective of any national boundaries.
• The waste must be removed and isolated from the effects of human activity or catastrophic natural events,
• the technology to implement disposal must be readily available as well as achievable at a reasonable cost,
• The burden on future generations shall be limited by implementing “at an appropriate time” a final disposal option which does not rely for its safety on long-term institutional controls or remedial actions.– in some countries, the retrieval of some types of disposed nuclear
wastes must be technologically and economically feasible, if so desired by future generations,
• The processes which control safe performance of nuclear waste disposal must be well-characterized by modeling.
• Sufficient, relevant data should be obtained and used in such models to demonstrate predicted performance reliably.
Week 2 (7/1):Performance assessment of
geologic disposal
Performance assessmentCan the environmental impact be
reduced by recycling?
Performance assessment
Performance Assessment (PA) ,Total System Performance Assessment (TSPA),
Safety Assessment
• PA: method for evaluation system, subsystem or component performance
• TSPA: a system-level PA; subsystems and components are linked into a single analysis
• Safety Assessment: if the result of TSPA is compared with a safety standard and judgment is made, TSPA is called safety assessment. (For YMR, TSPA = SA)
Annual Dose as the repository performance measure
Biospheredose conversion
factor, Bi (mrem/yr)/(Ci/m3)
Annual dose, BiCi mrem/yr
Repository
Geosphere
Plume of radionuclides
Release, Fi(t)
Local nuclide concentration, Ci(r,t)
wel
l
Near field Far field
Biosphere
Barriers Evaluated in the Analysis• Surficial soils and topography
• Unsaturated rock layers overlying the repository
• Drip shield
• Waste package
• Spent fuel cladding
• Waste form / concentration limits
• Drift invert
• Unsaturated rock layers below repository
• Tuff and alluvial aquifers
Emplacement Drift
Emplacement drifts5.5 m diameter50-90 drifts, each ~ 1 km long
The Emplacement Environment at Yucca Mountain
Thermal hydraulic conditions around emplacement drifts
Thermal Design GoalsRequirement Description
Tclad < 350°C Limit to prevent clad failure by increase in creep rupture.
TDW < 200°C Prevents alteration of rock crystalline structure.
Tcenter < 96°C Pillar Drainage requirement, creates flow path for water.
Natural System of Yucca Mountain
Desert Environment
Unsaturated Host Rock
UnderlyingUnsaturatedRock
Deep WaterTable
Unsaturated Overburden
Repository Horizon
Repository located:
~1,000 ft. Below Surface
~1,000 ft. Above Water Table
Estimating Dose to Hypothetical Future Humans
Total System Performance Assessment Architecture
Total System Performance Assessment Results Total Mean and Median Annual Dose(Draft Supplemental EIS, Oct. 2007)
Total Expected Dose: 10,000 years(Draft Supplemental EIS, Oct. 2007)
Radionuclides Contributing to Total Mean Dose at 10,000 Years
(Draft Supplemental EIS, Oct. 2007)
Summary of 10,000-year Results(Draft Supplemental EIS, Oct. 2007)
• Total mean dose determined by contribution from seismic scenario class– Probability of damage to co-disposed waste packages
within 10,000 yr < 0.2• Largest contribution to mean dose from 99Tc• Magnitude of mean dose determined by
– Probability of events (seismic, igneous)– Diffusion of radionuclides through cracks in waste
package outer barrier• Total estimated peak mean annual dose for
10,000 years: 0.24 mrem/yr– Well below regulatory limit of 15 mrem/yr
Total Expected Dose: 1 million years(Draft Supplemental EIS, Oct. 2007)
Radionuclides Contributing to Total Mean Dose at 1 million Years
(Draft Supplemental EIS, Oct. 2007)
Summary of 1 million-year Results(Draft Supplemental EIS, Oct. 2007)
• Total mean dose determined by occurrence of igneous events, seismic damage and general corrosion
• Major contributors to dose are 99Tc, 129I, 239Pu, 242Pu, 226Ra, and 237Np
• Waste package outer barrier has primary influence on releases of technetium and iodine
• Chemistry influences release of plutonium from waste package
• Total estimated peak median annual dose for 1 million years: 0.96 mrem/yr– Well below proposed regulatory limit of 350 mrem/yr
Steps for TSPADetail models ––A calculation typically includes only a subset of the repository system. The calculation produces predictions that can be compared with laboratory or field data.System models ––A calculation produces assessment of regulatory performance measures and the uncertainty in the performance measures caused by the parameter and model uncertainties in the analysis.
Evolution of Previous TSPAs
Model Development for TSPA
Data
ProcessModel
Abstraction
Two Major Issues with Geologic Disposal
• Repository Capacity for future nuclear-power utilization
• Uncertainty and Confidence building in long-term performance assessment
Types of uncertainty• Aleatory:
– arises from an inherent randomness– Stochastic, irreducible, Type A
• Epistemic:– Derives from a lack of knowledge about the appropriate value to
use for a quantity that is assumed to have a fixed value.– Subjective, reducible, Type B
• Examples– Regulatory uncertainty (Epistemic)– Conceptual-model uncertainty (Epistemic)– Model parameter uncertainty (Epistemic)– Stochastic uncertainty (Aleatory)
Regulatory uncertainty
• How can “repository performance” be measured?
• How can a technical safety case be justified within the regulatory framework?– Safety criteria are themselves uncertain.
Congress, EPA, NRC, DOE
Cong-ress
EPA（Standard）
NRC（Regulation）
DOE（Guideline）
１９８０－８５ １９８５－９０ １９９５－００ ２０００－０５１９９０－９５ ２００５－１０
NWPA1982
NWPAA1987
EnPA1992
WIPPLWA1992
VA1996
Site RecBy Energy Sec.
2002
40CFRPart 191
1985
40CFR191DENIAL
1987
40CFR191amended
1993
40CFR194WIPP1998
40CFR197YMR2001
Report for2nd repository
2008-10
40CFR197DENIAL
200440CFR197proposal
2005
10CFR60Procedure
198110CFR60Technical
1983
10CFR60Un-satu’d
198510CFR60
NEPA1989
10CFR60Pre-closure
199610CFR63
YMR2001
10CFR9601984
10CFR9632001
TSPA1991
TSPA1993
TSPA1995
TSPA-VA1998
TSPA-SR2001
License ApplicationAnd review2008-2011
Mass of stored SFExceeds YMR
capacity2014
Nuclear Waste Policy Act (1982)
• Set the schedule for siting 2 repositories.• EPA was charged with issuing generally
applicable limits on radioactivity releasesto the environment. (40CFR191)
• NRC was directed to develop regulations and criteria for construction, operation, and closure. (10CFR60)
• 1986: 9 sites ––> 5 sites ––> 3 sites – Deaf Smith, Hanford, Yucca Mountain
NWPA Amendment Act (1987)
• Only Yucca Mountain be characterized to evaluate its suitability as a repository.
• No site-specific work for a second repository.
• Nullified the DOE proposal for MRS at the Clinch River, TN.
• Site Characterization Plan for YM (1988)
10CFR60 (1983)
• Waste-package lifetime > ~1000 yr• Radionuclide fractional release rate from
EBS < 1/100,000 of its 1,000 yr inventory• Groundwater travel time > 1,000 yr• Overall performance: radionuclide release
to the accessible environment (40CFR191).
40CFR191 (1985)
• Disposal systems shall be designed so that for 10,000 years the following limits will not be exceeded at the accessible environmentwith the likelihood of – < 1 chance in 10 of exceeding the limit, and– < 1 chance in 1000 of exceeding 10 times the
limit.• Release limits are set on the basis of 1,000
MTHM.– I-129: 100 Ci, Sr-90: 1000 Ci, – Np-237: 100 Ci, Th-230: 10 Ci
Energy Policy Act (1992)
• Mandated a separate process for setting a standard specifically for YMR.
• Required EPA to arrange for an analysis by National Academy of Sciences (NAS).– Can scientifically justifiable analyses of
repository behavior over many thousands of years in the future be made?
• EPA reissued revised 40CFR191 in 1993.
Recommendations by NAS Report (1995)
• Denial of release limits, i.e., 1000 incremental fatalities over 10,000 years – The use of a standard that sets a limit on the risk to individuals of
adverse health effects from releases from the repository is recommended.
– The critical-group approach should be used.• Extension of time frame from 10,000 yr to a million yr
– The compliance with the standard measured at the time of peak risk, within the limits imposed by the long-term stability of the geologic environment, which is of the order of one million years.
• Denial of risk-based calculation of the adverse effect of human intrusion into the repository– The consequence of an intrusion should be calculated to assess the
resilience of the repository to intrusion.
10 CFR Part 63 was rejected by the federal appeals court due to a lawsuit
by Nevada State, July 2004.• Post Closure Performance Assessment
– Computer simulation of repository performance over 10,000 years to:
• Consider geologic and engineered barriers• Determine capabilities and time period to prevent or retards
movement of water and radionuclides• Calculate radiological dose at 18 km (using lab and field
evidence for simulations)– DOE must demonstrate using performance
assessment, that for 10,000 years the “reasonably, maximally exposed individual” receives no more than 15 mrem per year from all pathways releases of undisturbed YM disposal system.
Nominal Performance case with proposed standard （TSPA-VA)
15mrem/year
350mrem/year
Total System Performance Assessment Results Total Mean and Median Annual Dose(Draft Supplemental EIS, Oct. 2007)
Some thoughts about geologic disposal
• Retrievability of wastes from a repository– Final disposal vs. interim storage
• Fairness/Equity to future generations– Who are “future generations”?
• Fairness/Equity to the local community around the repository site– Why Nevada, where no nuclear power plants exist?
• “Natural Barrier”– May we contaminate rocks?
• Relationship with recycle/reprocessing– Is recycle effective in improving repository performance?
Some thoughts about performance assessment (PA)
• Performance assessment is:– based on scientific facts and abstracted reality, and – used as a tool for objective and optimized societal decision.– a good way to communicate with the public?
• Annual dose as the performance measure for judgment of long-term “environmental” safety.– Should be understood as a “stylized” measure.
• The biosphere part of PA model is based on hypothetical assumptions.
• This is actually not a measure for environmental safety, but radiological safety.
– What kind of (technical) information needs to be provided by PA for societal decision-making?
Can the environmental impact be reduced by recycling?
“IMPACT”
Repository
Nuclear Fuel Cycle
M
Uranium
Fuel cycle
System parametersd1, d2, p2, αf, γ1,γ2, …
Nuclear system
Environment
System parametersv, D, C*, ε, εp, d,
L, R, K, N, …waste
SeparationProcess
ProcessLoss
Reactor
SolidificationMatrix
Fuel Fabrication
Generation of long-lived FPs in LWRs(3410 MWt, 33,000 MWD/MT, 150-day cooling)
Half-lives fraction (%) nuclides< 1 yr 4.81 to 10 yr 1.3 Ru-106, Sb-125, Cs-134, Pm-147,
Eu-154, Eu-15510 to 30 yr 5.3 Kr-85 (11 yr), Sr-90 (29 yr), Cs-137 (30 yr)30 to 100 yr 0.03 Sm-151100 to 10,000 yr 0.0 N.A.1E4 to 5E9 yr 6.6 Se-79, Zr-93, Tc-99 (2.1E5),
Pd-107, Sn-126, I-129(1.6E7)Cs-135 (2.3E6)
> 5E9 yr 7.6 Rb-87, In-115, Ce-142, Nd-144, Sm-147, Sm-148, Sm-149
Stable 78.1Total 100.0
Generation of minor actinides (MA) per year
Nuclide 3410 MWt PWR3 yr cooling 10 yr cooling
Np-237 57.9 % 41.3Am-241 27.4 48.8*Am-243 11.9 8.33Cm-243 0.03 0.02Cm-244 2.67 1.44Cm-245 0.15 0.10Total 100 100
*Am-241 increases due to beta decay of Pu-241.
Partitioning and Transmutation of HLW
• By destruction of long-lived radionuclides in HLW,– Radioactivity and radiotoxicity of long-lived HLW are reduced– risk for future recovery of nuclear weapons materials from a final
repository is reduced– additional nuclear energy is gained by fissioning minor actinides
• For P-T, – Reprocessing is a prerequisite– Total radiological hazard arising from nuclear energy production
must be reduced. – Secondary wastes from P-T processes must be taken into
account.– Net energy production is desirable.– System must be economical.
Processes for P-T• Partitioning
– Conventional PUREX process + additional chemical partitioning processex. for Np, TRUEX has been developed.
– A process where separation of uranium and plutonium is combined with recovery of elements to be transmuted.
ex. pyrochemical processing• Transmutation
– Reactors• LWR, FBR for electricity generation + actinide burners• Th-U fuel cycle
– Accelerator• high-energy proton spallation
(n, fission), (n, gamma), (n, 2n), (n, p) reactionsphoto-nuclear reaction (gamma, n)
– Fusion reactor
P&T benefits
Toxicity Index
Toxicity index = λi Ni
Ci,kΣ
i[m3]
whereCi,k : radioactivity concentration limit for nuclide i in medium k
(k = water or air) [Bq/m3], Ni: the number of atoms of nuclide I
If more than one radionuclide is involved, a summation is performed over all the isotopes present in the mixture.
Toxicity index is the volume of air or water with which the mixture of radionuclides must be diluted so that breathing the air or drinking the water will result in accumulation of radiation dose at a rate no greater than 0.5 rem/year.
P-T flow sheet
Geologic disposal and P&T (1)• 1970s
– Several disposal concepts were investigated and compared from scientific viewpoints.
– Geologic repository concept • 1977 Polvani Report (OECD/NEA)• 1977 Stripa Project in Sweden
– Partitioning and Transmutation was proposed as an alternativeto geologic disposal
• 1980s– Scientific studies to demonstrate the safety of geologic disposal
• OECD International Symposium on Safety assessment of radioactive waste repositories, Paris 1989
– Denial of P&T concepts as an alternative to geologic disposal• International Conference on Partitioning and Transmutation, Ispra,
1980• UCBNE4176, Prof. T.H. Pigford, Paper presented at MIT
conference• L. D. Ramspott, et al., “Impacts of New Developments in Partitioning
and Transmutation on the Disposal of High-Level Nuclear Waste in a Mined Geologic Repository,” UCRL ID-109203, LLNL, March 1992.
UCBNE4176, 1990 by Pigford(In the framework of 40CFR191)
1. By recycling actinides, the length of time that needs to be considered for geologic disposal would not decrease from 100,000 yr to 1000yr, as claimed by P&T studies.
2. P&T is not necessary to satisfy 40CFR191 requirement for cumulative release of radionuclides to the environment at 10,000yr.
3. To have significant reduction of actinide inventory in a cycle, it will require more than 1000 yr of operation of P&T system to reach a steady state. Even in such a case, reduction better than 1/1000 is not possible.
Geologic disposal and P&T (2)• 1990s
– Demonstration of geologic disposal concepts (more site specific studies)– Shifting from natural barrier to engineered barriers
• TSPA studies in US for Yucca Mountain Repository• SKB report, Sweden, 1991• H3 and H12 reports, Japan, 1991, 1999
– P&T to improve repository performance• EC/EU Framework• France: SPIN project• OECD/Japan OMEGA project• US Liquid metal cooled actinide burner with pyroprocessing at ANL
• 2000s– Sites for repositories announced
• YMR (US), Olkiluoto (Finland)– Repository capacity issue has emerged.– P&T and advanced fuel cycle
• Generation IV• AFCI/GNEP
Results of Swedish repository-performance study
I-129
Dose limit（0.15mSv/y）
Water-Saturated repository (Japanese repository concept, H12)
Surface EnvironmentGeosphereEngineered Barrier System
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
104
Dos
e [ μSv
/y]
100 101 102 103 104 105 106 107 108
Time after disposal [y]
Th-229
Cs-135Se-79 Pb-210
U-238U-234
Total
Np-237
Time after disposal [y]
Cal
cula
ted
dose
[μSv
y-1 ]
LifestyleSurface EnvironmentGeosphereEngineered Barrier System
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
104
Dos
e [ μSv
/y]
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
104
Dos
e [ μSv
/y]
100 101 102 103 104 105 106 107 108
Time after disposal [y]100 101 102 103 104 105 106 107 108
Time after disposal [y]
Th-229
Cs-135Se-79 Pb-210
U-238U-234
TotalTotal
Np-237
Time after disposal [y]
Cal
cula
ted
dose
[μSv
y-1 ]
Cal
cula
ted
dose
[μSv
y-1 ]
Lifestyle
Effects of P&T in terms of exposure dose rate (H12)
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08
処分後の時間 [y]
総線
量 [
μSv/y] Reference case
99% actinide removed
Wakasugi, et al., Personal communications
Time after emplacement in repository, year
All other things being equal, less inventory means less risk. However, the risk reduction benefits that P-T might offer depend on the release scenario involved, and in many cases, may not be as great as a 99.9% reduction in actinide inventory might suggest.
Repository performance is insensitive to P/T application
-- L. D. Ramspott, et al., “Impacts of New Developments in Partitioning and Transmutation on the Disposal of High-Level Nuclear Waste in a Mined Geologic Repository,” UCRL ID-109203, LLNL, March 1992.
So, can the environmental impact be reduced by recycle?
• Yes, it can.• However, whether reduction is meaningful or not
depends on– combination of (a) waste form, (b) separation efficiency, and (c)
performance measures, suitable for geo-hydrological and geochemical conditions of the repository.
• Environmental impact reduction would not necessarily be the motivation for recycle; – U resource utilization and proliferation resistance of the
repository could be more important.• Environmental impacts from other parts of the fuel cycle
would directly be imposed on the current people, not those in 10,000 years in future. Thus, comparison or combination with other EI should be done carefully.
Week 3 (7/8):Societal and ethical issues of
geologic disposal
Development of societal agreement for geologic disposal
Ethics of geologic disposal
Development of societal agreement for geologic disposal
The Repository World
• Disposal in a geologic repository remains the preferred ultimatesolution, with or without reprocessing
• Much of the technical community has confidence in determining site suitability
• A number of geologic media are being pursued• Most programs have experienced substantial difficulties• Siting remains the biggest hurdle• Increasing recognition of multi-disciplinary nature• Select ideas have become prominent, e.g. volunteer/veto,
retrievability, monitoring, phased management• We will have storage for decades
Some Highlights and Lowlights
• National programs have been abandoned or sitingstopped– France, U.K., Canada, Germany, Spain, Switzerland, U.S.A.
• National (re)reviews have been undertaken– Canada, France, U.K.,…
• Schedules have been delayed– Almost everywhere
• Some countries have moved forward and others have restarted– Finland, Sweden, U.S.A., France, Canada, Japan, U.K….
An (Optimistic) Current Snapshot
• Countries with candidate sites– Finland, Sweden, U.S.A., France
• Countries with programs underway– Canada, Belgium, Japan, U.K., Switzerland,…
• Countries “thinking about it”– Spain, South Korea, China, India,…
• Countries starting out– Argentina, Slovakia, Slovenia, South Africa,…
The Seaborn Panel Conclusions (1998)--Canada--
• “From a technical perspective, safety of the AECL concept has been on balance adequately demonstrated for a conceptual stage of development. But from a social perspective, it has not.”
• “As it stands, the AECL concept for deep geological disposal has not been demonstrated to have broad public support. The concept in its current form does not have the required level of acceptability to be adopted as Canada’s approach for managing nuclear fuel wastes.”
NWMO Techniques for Broad Engagement
“Choosing a Way Forward”:The Foundation
• “…this generation of citizens which has enjoyed the benefits of nuclear energy has an obligation to begin provision for managing that waste.”
• “…our obligation is to give them (succeeding generations) a real choice and the opportunity to shape their own decisions while at the same time not imposing a burden which future generations may not be able to manage.”
“Choosing a Way Forward”:Some Key Recommendations
• Sequential decision-making and flexibility in the pace and manner of implementation through “Adaptive Phased Management”
• Ultimate centralized isolation in a deep geologic repository
• Option for interim step of shallow underground storage at the central site
• Program of continuous learning and R&D
• Long-term monitoring with potential for retrievability
• Seek an informed, willing community as host
What makes nuclear waste management special?
• The technical challenge– Performance over geological time– “Proof” not possible– Central role of “ologists”
• The institutional challenge– The extraordinary time frame– Siting– Linkage to other agendas– Values and ethics in conflict– Political implications– Nuclear stigma and fears
» But there are unique advantages…
Virtues of a Repository
• Passive• Occurrences will be slow• No inherent energy to release materials• Retrievable• Only a repository upon closure, when future
generations are comfortable
Some Key Enduring Features• Core, stable goal
• Roles and responsibilities clear
• Clear, open, and transparent decision making process
• Respect for fairness and societal consent apparent
• Sequential decision-making and contingency planning
• Possibility of altering or reversing course
• Appropriate compensation
Some Potential Lessons Learned• Take the necessary time - go slow in order to go fast
• Assign importance to the societal considerations as well as the technical ones
• There are many ways to effectively engage the public and key stakeholders
• Listening, respecting, and then responding can build trust and even advocacy, particularly with local community
• Plan carefully and involve the right experts
• Be prepared to respond in real time to unexpected events
• Promise, then deliver, then do it again and again
Ethics of geologic disposal
three main virtues that have withstood the test of time
• Humility• Charity• Veracity
Humility
Humility means you should treat yourself fully as one, but not more than one.
• How does this apply when you have a group of people (a corporation/government) that want to install a nuclear plant/geologic repository?
• Is it considering that that group of people may have different priorities than the group of people that they are affecting by installing the plant?
• Is it the mentality that installing a power plant will affect each person in their own situation differently?
• How do we reconcile these differences?
CharityCharity means that you should treat others as fully one,
just the same as you treat yourself.
• Should the groups of people that run corporations consider the groups of people that are affected by their projects as equal to them?
• Should the people that are affected consider the corporations equal?
• Who’s right is it to decide whether a project should go forward? The people affected? Corporations? Government?
VeracityVeracity simply means telling the truth.
• It has already proven successful for some countries to be completely open and honest with the people who will be affected by power plant projects.
• It has been shown that when the company or government that is planning the project takes the time to sit down and discuss the plans with the people, they are more receptive to the project.
• How important is it when it comes to these issues for corporations? The government?
Consequentialism （帰結主義）G.E.M. Anscombe, "Modern Moral Philosophy" (1958)
• Actions are evaluated based on the results they achieve.
• A morally right action is one that produces a good outcome, or consequence.
• The ethical action is the one that maximizes overall good.
• Such theories are labeled teleological（目的論的）.• A consequentialist may argue that lying is wrong
because of the negative consequences produced by lying — though a consequentialist may allow that certain foreseeable consequences might make lying acceptable.
Utilitarianism（功利主義）John Stuart Mill's essay Utilitarianism (1861)
• “the greatest good for the greatest number”（最大多数の最大幸福）
• the moral worth of an action is solely determined by its contribution to overall utility, that is, its contribution to happiness or pleasure as summed among all persons.
Deontology（義務論）
• Actions are evaluated based on the motivation behind them.
• Deontology derives the rightness or wrongness of an act from the character of the act itself.
• A deontologist might argue that lying is always wrong, regardless of any potential "good" that might come from lying.
Kant’s three significant formulations of the categorical imperative
(deontological)• Act only according to that maxim by which you
can also will that it would become a universal law.
• Act in such a way that you always treat humanity, whether in your own person or in the person of any other, never simply as a means, but always at the same time as an end.
• Act as though you were, through your maxims, a law-making member of a kingdom of ends.
Conflicting motives
• Consequentialism seeks the best outcome, despite the action.
• Deontology seeks the best action, despite the consequences.
ANS Code of Ethicshttp://www.ans.org/about/coe/
1. We hold paramount the safety, health, and welfare of the public and fellow workers, work to protect the environment, and strive to comply with the principles of sustainable development in the performance of our professional duties.
2. We will formally advise our employers, clients, or any appropriate authority and, if warranted, consider further disclosure, if and when we perceive that pursuit of our professional duties might have adverse consequences for the present or future public and fellow worker health and safety or the environment. (veracity)
ANS Code of Ethicshttp://www.ans.org/about/coe/
3. We act in accordance with all applicable laws and these Practices, lend support to others who strive to do likewise, and report violations to appropriate authorities. (veracity, humility)
4. We perform only those services that we are qualified by training or experience to perform, and provide full disclosure of our qualifications. (humility)
5. We present all data and claims, with their bases, truthfully, and are honest and truthful in all aspects of our professional activities. We issue public statements and make presentations on professional matters in an objective and truthful manner. (veracity)
ANS Code of Ethicshttp://www.ans.org/about/coe/
6. We continue our professional development and maintain an ethical commitment throughout our careers, encourage similar actions by our colleagues, and provide opportunities for the professional and ethical training of those persons under our supervision.
7. We act in a professional and ethical manner towards each employer or client and act as faithful agents or trustees, disclosing nothing of a proprietary nature concerning the business affairs or technical processes of any present or former client or employer without specific consent, unless necessary to abide by other provisions of this Code or applicable laws.
ANS Code of Ethicshttp://www.ans.org/about/coe/
8. We disclose to affected parties, known or potential conflicts of interest or other circumstances, which might influence, or appear to influence, our judgment or impair the fairness or quality of our performance.
9. We treat all persons fairly. (Charity)10. We build our professional reputation on the
merit of our services, do not compete unfairly with others, and avoid injuring others, their property, reputation, or employment.
11. We reject bribery and coercion in all their forms.
ANS Code of Ethicshttp://www.ans.org/about/coe/
12. We accept responsibility for our actions; are open to and acknowledge criticism of our work; offer honest criticism of the work of others; properly credit the contributions of others; and do not accept credit for work not our own. (humility, veracity)
Ethics in Nuclear Engineering• ANS Code of Ethics reflects a Deontological approach of
obeying a set of rules or principles. 9th point specifically mirrors Kant’s Categorical Imperative.
• This contrasts, however, with the Consequentialism approach which is taken in the matter of waste disposal.
• The potential for greater good for the greater number of people is considered more important than the action, which puts people at risk.
Yucca Mountain• Yucca Mountain seemingly contradicts two tenets
of the ANS Code of Ethics: – 1) welfare of the public, and – 9) We treat all persons fairly
• is it fair that Nevada gets a site when they have no nuclear power, and have been lied to in the past?
• Utilitarianism is the basis for ethics (greatest good for the greatest #), but we still shouldn’t violate the code of ethics, (#9)?
• In utilitarianistic consideration, is future generation included?
Week 4 (7/15):International aspects of nuclear
power utilization
(Introductory summary for nuclear activities in India)
(Comparative discussions among Japan, US, and India)
(Introductory summary for nuclear activities in India
by Dr. R. K. Dayal, IGCAR)
Topics to be Discussed in This Week
• As Asian economy expands rapidly, so does energy demand in Asia. – Why is this so important to us (or the US)?
• Nuclear Energy is an indispensable choice for Asian countries.– Are they ready for nuclear energy?– How will it influence the world in the future?– What is needed most there? And how can the
US respond to such needs?
Chinese Development Plan of Nuclear Power Units to 2020
NPPs in operation and under construction
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
1982年1986年
1990年1994年
1998年2002年
2006年2010年
2014年2018年
Pow
er C
apac
ity (M
We) under construction
in operation
9,068MW
1981-20077,860MW
2004- 2014
26,000MW2008- 2020
1.8% 4.0%
Scenarios for Total Installed Power Capacity in India
(DAE-2004 and Planning Commission-2006 studies)
0
200
400
600
800
1000
1200
1400
1600
1990 2000 2010 2020 2030 2040 2050 2060
Year
GW
e
DAE PC_GDP-Growth 8% PC_GDP-Growth 9%
Electricity growth rate Electricity growth rate –– a scenarioa scenario
PeriodPeriod Primary Primary energy % annual energy % annual
growthgrowth
Electricity Electricity % annual growth% annual growth
2002-2022 4.6 6.32022-2032 4.5 4.92032-2042 4.5 4.62042-2052 3.9 3.9
5305
3699
2454
1620
1000613
0
1000
2000
3000
4000
5000
6000
2002 2012 2022 2032 2042 2052
Time period
Per C
apita
Gen
erat
ion
(kW
h)
GDP/capita vs. kWh/capita
100
1000
10000
100 1000 10000 100000
China
kWh/
capi
ta
GDP/capita (US$)
India
Sri Lanka
Indonesia
Philippines
Thailand
MalaysiaSouth Korea
Hong Kong
SingaporeBrunei JapanFrom 1999 to 2006
US (2006)($44,000, 13,000 kWh)
By Increase in Energy Consumption in Asia ....
• Global Environment– CO2, SOx, NOx emissions
• Greenhouse effect, Acid Rain, etc.
• Competition for Limited Resources• Nuclear Safety and Security• International System
– If nuclear energy is developed on a large scale, restructuring of international organizations for safeguards will be necessary.
The Global Nuclear Energy Partnership Objectives are Stated in The National Security Strategy
• The United States “will build the Global Nuclear Energy Partnership to work with other nations to develop and deploy advanced nuclear recycling and reactor technologies.
• This initiative will help provide reliable, emission-free energy with less of the waste burden of older technologies and without making available separated plutonium that could be used by rogue states or terroristsfor nuclear weapons.
• These new technologies will make possible a dramatic expansion of safe, clean nuclear energy to help meet the growing global energy demand.”
GNEP Process
Spent fuel accumulation in South Korea
0
10
20
30
40
50
60
70
80
90
2005 2015 2025 2035 2045 2055 2065 2075 2085 2095
Year
Acc
umul
ated
SF
Aris
ings
(ktH
M)
PWR
CANDU
0
10
20
30
40
50
60
70
80
90
2005 2015 2025 2035 2045 2055 2065 2075 2085 2095
Year
Acc
umul
ated
SF
Aris
ings
(ktH
M)
PWR
CANDU
Spen
t Fue
l Acc
umul
atio
n (k
tHM
)
(Comparative discussions among Japan, US, and India)
Discussion topics• Developed vs. developing countries
– Resources– Global environment– Proliferation resistance – Access to technologies
• For whom? Why?• Current vs. future generations
– Resources– Global environment
• Nuclear vs. non-nuclear communities– Public perception and communication– Decision making processes