Transcript CN242_NUMO_safety_case_Fujiyama_finalx

Development of the NUMO pre-selection,
site-specific safety case
24th November 2016, Vienna, Austria
International Conference on the Safety of
Radioactive Waste Management, IAEA
Nuclear Waste Management Organization of Japan (NUMO)
Tetsuo Fujiyama, Satoru Suzuki,
Akira Deguchi, Hiroyuki Umeki
P.0
Evolution of geological disposal programme in Japan
 In 1999, the “H12 Report” was published by JNC (now JAEA),
which demonstrated the feasibility of safe geological disposal of
HLW based on a generic study.
 On the basis of the H12 Report, “the Final Disposal Act” for
implementing geological disposal of HLW came into force and
NUMO was established in 2000.
 NUMO initiated the siting process by open solicitation of
volunteer municipalities in 2002.
 ILW (termed “TRU waste” in Japan) was also included in NUMO’s
remit by amendment of the Act in 2007.
…. The Great East Japan Earthquake and the Fukushima Dai-ichi
NPP accident in 2011 increased nationwide concerns about the
feasibility and reliability of geological disposal in Japan
 No volunteer municipality has appeared and no candidate host
rock type has been specified as yet.
P.1
Why make the NUMO Safety Case?
 “The Basic Policy”, based on the Final Disposal Act, was amended
in 2015, which involves that the Government will nominate
scientifically suitable areas to initiate discussions and cooperation
with local municipalities, finally leading to acceptance of a site
investigation, which will be carried out by NUMO.
 It is important at this time to present technical evidence to
support the feasibility and safety of geological disposal, which
will encourage stakeholder support of implementation
 NUMO has developed the “NUMO pre-selection, site-specific
safety case”
 Development of site descriptive models (SDMs) on the basis
of field data obtained at URLs, provides a more advanced
site-specific basis than the H12 Report.
P.2
Staged site
investigation
Providing
the
basic safetyprocess
case structure
Literature
Preliminary
Literature
Preliminary
Investigation Stage
Investigation
Stage
At this stage
Investigation Stage
Nationwide literatureLiterature survey
Literature survey
Investigation Stage
Surface based
Surface based
investigations
investigations
Setting of candidate
Exclusion
of unsuitable
Exclusion of unsuitable
Investigation
Exclusion of
unsuitable
host rock typeExclusion of unsuitable sites
sites
sites
sites
and
Estimation of geological
Understanding geological
evaluation of
environment Understanding geological
environment
Estimation of geological
Development
of
SDM
characteristics
the
characteristics
environment
environment
characteristics
geological
characteristics
Development of SDM
Update of SDM
environment
Trial design of
repository
Development of SDM
Outline of initial
repository concept
Repository
Trial safety
design
Outline of initial
Outline of safety
repository concept
assessment
assessment
Safety
Assessment
Next technical
Outline of safety
Selection of PI areas
assessment Planning of PI stage
Update Preliminary
of SDM design of
disposal facility
Preliminary design of
disposal Preliminary
facility safety
assessment
Preliminary
safetyof DI areas
Selection
assessment
Planning of DI stage
development plan
Selection of PI areas
Planning of PI stage
The basic safety
case structure
Selection of DI areas
Planning of DI stage
Detailed
Detailedstage
Investigation
Investigation stage
Surface
based investigations
Surface based investigations
Investigations
ininthe
Investigations
the UIF
UIF
Confirmation
thatsite
site is
is
Confirmation
that
suitable
suitable
Detailed understanding of
geological
environmentof
Detailed
understanding
characteristics
geological
environment
characteristics
Update of SDM
Update
of of
SDM
Basic
design
disposal
facility
Basic design of disposal
facilityassessment
Basic safety
Selection of the
Basic safety
assessment
repository site
Selection of the
repository site
Development and review of the safety case
Development and review of the safety case
P.3
Documents and target audience
For geological
disposal experts
For others
 The geological
disposal community
 Engineers & Technologists
 Scientific communicators
 General public
Executive summary
30 pages
NUMO Safety
Case Report
Main Report
350 pages
Supporting Reports
Detailed background to support
the main report
178 documents, Total 4800 pages
Reference R&D reports
NUMO-TR, JAEA-Research, CRIEPI-Reports,
Scientific papers etc.
Abridged report
PR materials
(Describing mainly key
messages of SC with simple
text, 50 pages)
(brochures )
 Why geological disposal?
 Basic concept of
geological disposal
 Basic Safety strategy
 Stepwise approach
 Reversibility
 Transparency
・
・
・
Principles and safety of
geological disposal
Existence of suitable
geological environments
Safety in case of natural
hazards
Pre-closure safety
Retrievability of waste
Presented using a web-based communication platform
P.4
Contents of NUMO Safety Case report
1. Background and purpose
2. Safety strategy
3. Geological characterisation and synthesis
...developing geo/hydro models of potential host rock environments on the
basis of the state-of-the-art geoscientific knowledge
4. Repository design and engineering technology
...being performed on the basis of the models, providing underpinning
evidence to demonstrate the technical feasibility of geological disposal
5. Assessment of pre-closure safety
6. Assessment of post-closure long-term safety
...being performed on the basis of the models, providing underpinning
evidence to demonstrate the long-term safety of geological disposal
8. Confidence in the technical feasibility of geological disposal in
Japan
9. Conclusions
P.5
Five rock types excluding
Quaternary rocks and
Quaternary volcanic
Neogene sedimentary rocks
Pre-Neogene sedimentary rocks
Pre-Quaternary volcanic rocks
Pre-Quaternary plutonic rocks
Metamorphic rocks
Quaternary volcano and 15 km
radius circle from the centre
Based on AIST “Seamless Digital Geological
Map of Japan (1:200,000)” and “Volcanoes of
Japan (1:200,000), 3rd Edition”
P.6
6
Nested models for plutonic rocks
Highly fractured (weathered) domain
Sedimentary overburden
100~200 m
100~200 m
GW flow
1 km
 Fractured media
Granite
 Hard rock
Active fault
Active fault
Illustrative geological setting
L ≥1 km
L ≥1 km
L ≥10 m
Regional scale
Repository scale
Panel scale
(50 km x 50 km)
(5 km x 5 km)
(800 m x 800 m x 800 m)
P.7
Nested models for Neogene sedimentary rocks
Freshwater – saline
water transition
Quaternary sediments
(several tens of m)
 Porous media with low
density of fractures
GW flow
 Soft rock
Granite
Sea
500 m
Active fault
Basement
Active fault
Illustrative geological setting
L ≥25 m
Regional scale
Repository scale
Panel scale
(30 km x 30 km)
(5 km x 5 km)
(800 m x 800 m x 800 m)
P.8
Nested models for Pre-Neogene sedimentary rocks
Quaternary sediments (several tens of m)
Thrust
Freshwater – saline
water transition
GW flow
 Fractured media with
high density of fractures
 Hard rock
Sea
1000m
Illustrative geological setting
Regional scale
Repository scale
Panel scale
(40 km x 40 km)
(5 km x 5 km)
(800 m x 800 m x 800 m)
P.9
Repository concepts to be considered in design study
HLW repository
TRU waste repository
Vertical emplacement
Vault waste emplacement
Concrete
support
支保工
Vitrified
waste
ガラス固化体
Overpack
オーバーパック
Backfill
埋め戻し材
Concrete
support
Pit
Backfill
Waste
packages
Buffer
緩衝材
(EBS)
Disposal hole
処分孔
（処分坑道）
（人工バリア）
Prefabricated
EBS module
(PEM)
Disposal drift
Overpack
Buffer
(Bentonite)
Vitrified waste
PEM
Backfill
Buffer
(Bentonite)
Metal shell
P.10
An example of underground panel layout
Plutonic rocks model
Short travel
time
Unpreferable area
Faults
(Length > 1 km)
5 km
予備区画
(TRU)
区画④
予備
区画
②
 Required scale of the facility:
 Total HLW: more than 40,000
canisters of vitrified waste
 Total TRU waste: more than
19,000 m3
‐
Relative migration time
+
予備
区画
④
予備区画
③
0
区画⑥
区画⑤
区画①
区画②
予備
区画
①
区画③
500m
Direction of ground water flow
P.11
Assessment of long-term post-closure safety
 Since safety standards for geological disposal in Japan have not,
as yet, been defined, the results of the safety assessment are
compared to international standards.
 A risk-informed approach is introduced, based on international
guidelines as well as recent national discussions on safety
regulations.
 Referring to the guidelines of international organisations on
assessment timescales, dose calculations are carried out for up
to one million years after closure.
 The advanced approach and methodology for radionuclide
transport modelling can be used to compare different sites and
disposal concepts.
P.12
Scenario classification and target dose
Scenario
classification
Definition
Target dose
Likely
Scenario
This scenario is used to assess the performance
of the geological disposal system based on the
best understanding of the probable evolution, as
a reference for the optimisation of protection.
Target value: 10
μSv/y
Less-likely
scenario
This scenario is used to assess the safety of the
geological disposal system in view of
uncertainties in scientific knowledge supporting
likely scenarios.
Safety reference
value: 0.3m Sv/y
Very unlikely
scenario
Possible scenarios with extremely low likelihood.
Reference value:
1～20 mSv/y
Human
intrusion
scenario
This scenario is used to check whether the
geological disposal system is robust with
assumption of human intrusion after loss of
institutional control.
Reference value；
Residents:
1～20 mSv/y
Intruder:
20～100 mSv/event
P.13
3D modeling of RN transportation
100m
Rock
EBS
Backfill (Bentonitesand mixture)
k=1.0×10-9 m/s
Deposition hole
100m
Cross section Shotcrete
of drift
t=50 mm
k=1.0×10-5 m/s (degraded)
EDZ
t=1000mm
Fracture transmissivity:100
times to the original value
Drain
k=1.0×10-5 m/s
Buffer
k=1.0×10-12 m/s
Faults and fractures are
represented by stochastic
modelling approaches, on
the basis of the site-specific
dataset obtained URLs.
EDZ
t=500mm
A 3D model is used to represent the geometry of the EBS components and
geosphere to realistically evaluate transportation of RN at the near-field scale.
P.14
Examples of safety assessment of HLW
Plutonic rock model
Maximum dose rate (μSv/y)
1E-4 1E-3 1E-2 1E-1 1E+0 1E+1 1E+2 1E+3 1E+4 1E+5
H12 Report - reference case
Likely scenario case / Plutonic rock
Likely scenario
(10 μSv/y)
Uncertainties in glass dissolution rate
Bentonite alteration due to Fe-silicate
minerals
Uncertainties in fracture distribution
Less-likely scenarios
(300 μSv/y)
Change of magnitude of hydraulic gradient
Uncertainties in radionuclide migration
parameters (Kd, De) of rock
Concealed active fault intersects the
repository
Human intrusion (exploration)
Very unlikely scenarios
(1~20 mSv/y)
Human intrusion
scenarios
P.15
Progress since H12 report
 Development of ‘realistic’ SDMs on the basis of key characteristics,
e.g. distribution of faults, fractures and their hydraulic
conductivities, in particular from studies in Japanese URLs since
2002.
 A practical methodology for tailoring repository design to
geological environments
 Engineering feasibility of technology for retrieving waste
 Pre-closure safety assessment of radiological protection during
waste handling in surface facilities
 The advanced approach and methodology for radionuclide
transport modelling can be applied to compare different site and
disposal concepts
 Development of management strategy for project implementation
(Quality Management, Knowledge Management, R&D, Strategy on human resources…)
P.16
Key conclusions
 “The NUMO pre-selection, site-specific safety case” provides the
basic structure for subsequent safety cases that will be applied
to any selected site, emphasising practical approaches and
methodology which will be applicable for the
conditions/constraints during an actual siting process.
 The preliminary results of the design and safety assessment
would underpin the feasibility and safety of geological disposal
in Japan.
P.17
Schedule for the NUMO SC report
January 2017



Finalisation of NUMO Safety Case report (for review, in Japanese)
Open to the public on a web-based communication platform
Start of domestic review by the Atomic Energy Society of Japan
Around July 2017
Finalisation of the NUMO Safety Case report (for review, in
English) reflecting comments from domestic and international
experts
 Application for international review (by OECD/NEA?)

P.18
Thank you for listening
P.19
Three Stages of the Site Selection Process
Municipalities
(Proposal by the
Government)
Preliminary
Investigation
Areas (PIAs)
Municipalities
(Open Solicitation)
Preliminary
Investigation
Literature
survey
- Geophysical survey
- Borehole drilling etc.
Selection
criteria
1st
stage
Detailed
Investigation
Areas (DIAs)
Detailed
Investigation
- Excavation of, and studies
in, RCF
- More extensive geophysics,
drilling, etc.
Selection
criteria
Selection
criteria
Selection
of PIAs
2nd
stage
Repository
Site (RS)
Late 2030s
Selection
of DIAs
3rd
stage
Selection
of RS
Government hearings with governors and mayors
P.20
Legal requirements for staged site selection
To ensure there is no record of significant
movement caused by tectonic activity, volcanic activity,
uplift and erosion or other phenomena in rock formations,
and also to ensure a low likelihood of similar significant
movement in the future
LS
To ensure the potential host rock formations and
their surroundings are stable and have no
obstructions to drift excavation or potentially small adverse
impacts on subsurface facilities by groundwater flow, etc
PI
To ensure the mechanical and chemical properties
of the host rock formation are suitable for repository
construction, etc
DI
21
P.21
Grouping of TRU waste in Japan for deep geological disposal
Group 1
Spent silver
absorbent
Group 2
Hulls
End-pieces
Group 3
Group 4 L/H
Solidified concentrated
liquid waste
NonPoorly
combustible combustible
waste
waste
Mortar
Content
Group 4L
Pellets
Vitrification furnaces
etc.
Dried
Iodine absorber
Group 4H
E.g.
E.g.
E.g.
Waste
package
E.g.
低レベル放射性廃棄物
Includes I-129
Heat generating;
Includes C-14
Includes nitrates from
PUREX reprocessing
Includes heat generating
glass melter wastes
P.22
– Management strategy
1) Management strategy
•
Develop management strategy for staged and flexible project implementation









Coordination and integration across different technology fields
Iterative confirmation of safety and development of the Safety Case
Risk Management during the project
Quality Management
Requirements Management
Knowledge Management
Establishing R&D Programmes
Strategy for human resources
Strategy for communication with stakeholders
(Red font; identifies advances compared with H12 Report)
P.23
Ch.3 Geological characterisation and synthesis
【Top level key statements】
 Potentially significant impacts of natural disruptive
events/processes on the geological environment can be
precluded.
 Stable geological environments can be identified and their 4D
evolution characterised.
 Geological models are developed for subsequent repository
design and safety assessment, by interpretation and synthesis of
the latest geoscientific information.
P.24
Nested modelling approach
LS: literature survey
Regional scale
(several tens of km)
Climatic change
PI: preliminary investigation
PI: supplementary
Repository scale
(several km)
Volcanic
activity
DI: detailed
investigation
Uplift/
erosion
Sea-level
change
Panel scale (several
hundreds of m)
Earthquake
Fault
movement
P.25
Procedure for developing realistic models
Latest nation-wide geoscientific information
Categorisation of potential host
rock environments
and identification of
representative types
Geological modelling of key
structures for each type
Hydrogeological modelling by
stipulating key parameters
Nationwide
dataset
Determination of
current
groundwater
flow regime
Sitespecific
dataset
Simulation of 4D
evolution of
groundwater
flow regime
Realistic models and boundary conditions for
repository design and safety assessment
P.26
Categorisation of potential host rock environments
Age
Rock type
Neogene
Pre-Neogene
Pre-Neogene Palaeozoic ~ Neogene
Sedimentary Volcanic Sedimentary Igneous Metamorphic
rock
rock
rock
rock
rock
Pore,
Fracture
Joint,
Fracture,
Pore
Fracture,
Bedding,
Cleavage
Fracture,
Joint,
Dyke
Fracture,
Schistosity
Hydraulic conductivity
High
High
Low
Low
Low
Effective porosity
High
Middle
Middle
Low
Low
Thermal conductivity
Low
Middle
Middle
Middle
High
Mechanical strength
Low
High
High
High
Middle
Long-term structural
evolution
High
Low
Low
Low
Low
Chemical buffering
High
Low
High
Low
Low
Abundance at -500m
28%
6%
37%
19%
7%
Abundance at -1000m
24%
1%
43%
24%
8%
Potential pathways
 Three types of potential host rock environments can be identified
P.27
Three types of SDMs and their features
In this “pre-selection, site specific” safety case, site descriptive models (SDMs) are developed
for three representative rock groups.
SDM
(Rock type)
Plutonic rocks
Neogene
sedimentary
rocks
Pre-Neogene
sedimentary
rocks*
Thermal
features
Hydraulic
features
Thermal gradient
3ºC/100 m
Fractured media
Thermal gradient
3ºC/100 m
Porous media
with low density of
fractures
Thermal gradient
3ºC/100 m
Fractured media
with high density
of fractures
Mechanical
features
Chemical
features
Hard rock
・Fresh/Saline
・Reducing condition
・Neutral to weakly
alkaline
Soft rock
・Fresh/Saline
・Reducing condition
・Neutral to weakly
alkaline
Hard rock
・Fresh/Saline
・Reducing condition
・Neutral to weakly
alkaline
*: A calculation case of performance assessment for pre-Neogene sedimentary rocks are
not carried out because the data are largely limited to surface data.
P.28
Regional scale model parameters
Scale
Model
Geological
Parameter
Density: fault/fracture
Regional
50 km x 50 km
HydroHydraulic conductivity:
geological
fault (>1 km)
Transmissivity:
fault/fracture (<1 km)
Panel
800 m x 800 m
x 800m
Nation-wide dataset (including geological
map, open publications, URL data, etc)
Orientation: fault/fracture
Hydraulic conductivity:
background fractured rock
Repository
3 km x 3 km
Mizunami URL
Nation-wide
dataset
Up-scaling of
panel scale
hydro-DFN
Nation-wide dataset
(anisotropy considered)
none
none
none
none
Mizunami URL
P.29
Regional scale models
Regional scale (50 km x 50 km) defined by
considering the longest fault length, size of
granite body at 1,000 mbgl and basin area of
first-class rivers;
Geological: DFN model
Geo-DFN model (L ≥1 km)
based on nation-wide
100
statistical fault density
10
and Mizunami fault
1
orientation data;
0.1
0.01
Hydrogeological: CPM
0.001
model based on K values
0.0001
assigned from nation0.00001 Power law
exponent value 4.0
wide dataset; defining
0.000001
10 10
1 10 10 10 10 10
Orientation of
BCs for repository scale
Length (m)
fault/fractures
SDM.
at Mizunami
3D density of fault/fractures
Tono outcrops
P32 (m2/m3)
Kamioka cavern
Kuji oil storage
Kikuma oil storage
Tono lineaments
Nation-wide faults
Nation-wide active
fault segments
-2
-1
2
3
4
5
P.30
Repository scale models
Focus on granite basement over
3 km x 3 km, 1 km deep;
underlying highly fractured
domain and sedimentary
overburden;
Geological: DFN model in the
same way as regional; basis for
interaction with RD to define
LDFs;
Hydrogeological: ECPM model
showing spatial K distribution by
up-scaling panel scale DFN
model; defining BCs for panel
scale SDM.
Geo-DFN model (L ≥1 km)
Fault distribution
left: L ≥500 m, right: L ≥100 m
P.31
Panel scale models
Focus on granite basement in 800 m cube encompassing possible
emplacement of a panel;
Geological: DFN model based on Mizunami fracture data;
Hydrogeological: DFN model based on Mizunami fracture T data;
modelling of fracture T frequency distribution by numerical
simulation of inflow in DFN model; providing input for refining layout
and EBS design.
0
(mabh)
Depth
深度 [mabh]
200
400
600
800
透水量係数 [m2/s]
Transmissivity (m2/s)
Geo-DFN model (L ≥10 m)
T distribution at Mizunami URL
0.
01
1E
-4
1E
-6
1E
-8
1E
-4
1E
-6
1E
-8
0.
01
1E
-1
2
1E
-1
0
透水量係数 [m2/s]
1E
-1
2
1E
-1
0
0.
01
1E
-4
1E
-6
1E
-8
1E
-1
2
1E
-1
0
1000
透水量係数 [m2/s]
Hydro-DFN model
P.32
Ch.4 Repository Design and Engineering
【Top level key statements】
 Alternative repository concepts allow flexibility in tailoring to the
wide-range of geological environments expected.
 The design methodology is demonstrated by carrying out a full
repository design study, tailored to the geological environment
models.
 The robustness of the EBS is evaluated based on state-of–theart materials science, with consideration of the wide-range of
geological environments.
 Engineering feasibility and quality assurance of technology for
construction, operation and closure of the repository are
described on the basis of experience in other relevant facilities.
 State-of-the-art technology for retrieving waste is described and
its engineering feasibility is shown.
P.33
Repository concept
Natural barrier
HLW
repository
Definition of the terms
•Natural barrier
•Engineered barrier
system (EBS)
•Closure system
(back fill/plug)
•Safety assessment
Repository concept
•Safety (long-term/operational)
•Engineering feasibility
•Economical aspect,…etc.
Procedures and technologies of
construction/operation/closure
Geological disposal
LLW repository
LLW EBS
HLW EBS
The long-term safety of the
geological disposal system
Engineering feasibility, operational
safety, efficiency and economic aspects
P.34
Selection of potential repository depth
• Sediments 100-200 m thick in general
• Highly fractured domain up to 200m thick in general
⇒ Set depth at least 100m into un-weathered domain
⇒ Repository at > ca. 500m below surface
• Mechanical stability of tunnels
⇒ depth limit; 1500m
• Thermal impact on EBS
⇒ depth limit; 1150m
Granite
• Constraint of working area temperature
⇒ depth limit; 1000m
Highly fractured (weathered) domain
Sedimentary overburden
GW flow
1km
Active fault
100~200m
100~200m
Active fault
Illustrative geological setting
 1000m is selected conservatively as
reference depth due to uncertainties at
LS stage (it will actually vary somewhat
due to surface topography)
P.35
Allocation of safety functions to each component of the engineered barriers
Concrete cell Backfill
Component
Phase
Safety function
Radiation shielding
Pre Confinement
closure
Mechanical stability
Restrict advective transport of RN
Waste
package
Gap
filler
o
o
o
o
Prevent the formation of short-cut
pathways along access tunnel
Backfill
Plug
o
o
o*
Prevent colloidal migration
Post Retardation of RN migration by
closure sorption
Concrete
Buffer
cell
o*
o
o
o
o
Gap filler
Buffer
Waste package
* Safety function of gap filler is not expected for the case of high heat
generation waste.
Configuration of the EBS of TRU
P.36
Correspondence of TRU grouping and EBS configuration
Grouping of TRU waste
Group
Waste-form
Features of the waste
• Contains much I-129
Spent silver absorbent for
Gr.1
• Low heat generation <1
iodine
W/unit
• Contains much C-14
Compressed hulls and
Gr.2 end pieces, CSD-B, CSD- • Relatively higher heat
C
generation 19W/unit
Configuration of EBS
Gr.1 and 2
From the point of view of retardation of
RN migration, includes buffer
Gr.2 and 4H
Because of gap filler will be done at a
high temperature, it might be difficult to
ensure quality related to sorption. So,
NUMO considered buffer is needed to
ensure barrier performance.
Buffer
Solidified low-level liquid
Gr.3 waste (bituminized or
mixed with mortar)
• Contains nitrate
• Low heat generation
3 W/unit
Gr.4L Combustible or non-
• Low heat generation
3 W/unit
combustible waste
packed with mortar or
Gr.4H other material
• Relatively higher heat
generation 60W/unit
Gap filler
Gr.3 and 4L
Buffer is
unnecessary
Gap filler
P.37
Tunnel design
Plutonic rock／Pre-Neogene sedimentary rock
rock bolt
rock bolt
liner
liner
Group. 2
Neogene sedimentary rock
Group. 3
rock bolt
rock bolt
liner
Tunnel support
liner
Tunnel support
secondary liner
Group. 2
secondary liner
Group. 3
 Tunnel design is considered waste distance, design of engineered barrier, operation
space.
 Tunnel support is designed by cavern stability analysis considering seismic effect.
P.38
Layout design of TRU waste repository
Plutonic rock/Pre-Neogene sedimentary rock
547.2m
547.2m
584.8m
584.8m
Gr.3
122.3m
20.0m
20.0m
Gr3_ドラム缶③
Gr4H_ハル缶・インナーバレル①
20.0m
20.0m
Gr4L_角型容器
Gr4H_ハル缶・インナーバレル①
44.1m
Gr4H_ドラム缶
20.0m
28.5m
20.0m
129.8m
20.0m
82.0m
Gr4L_ドラム缶②
168.4m
Gr4L_ドラム缶①
28.5m
20.0m
20.0m
20.0m
168.4m
Gr4L_ドラム缶①
180.6m
Gr2_キャニスター⑤
20.0m
144.8m
Gr2_キャニスター④
20.0m
20.0m
117.2m
110.3m
120.2m
20.0mGr3_ドラム缶③
Gr.4L
20.0m
20.0m
144.8m
Gr2_キャニスター③
20.0m
126.7m
44.1m
Gr4L_ドラム缶③
20.0m
153.9m
20.0m
20.0m
Gr4L_角型容器
Gr.4H
153.9m
Gr.3
Gr3_ドラム缶①
20.0m
34.2m
153.9m
20.0m
180.6m
Gr2_キャニスター⑤
20.0m
144.8m
Gr2_キャニスター④
20.0m
Gr4H_ドラム缶
138.5m
144.8m
Gr2_キャニスター②
20.0m
157.6m
Gr2_キャニスター①
20.0m
48.8m
144.8m
Gr2_キャニスター②
20.0m
157.6m
Gr2_キャニスター①
20.0m
20.0m
Gr4L_ドラム缶②
立坑
立坑
37.5m
20.0m
Gr4L_ドラム缶①
140.1m
138.5m
20.0m
20.0m
Hydraulic gradient
Gr2_キャニスター⑥
Gr4L_ドラム缶②
20.0m
185.8m
Gr2_キャニスター⑤
20.0m
138.5m
Gr4L_ドラム缶①
アクセス斜坑へ
20.0m
138.5m
Gr4L_ドラム缶③
20.0m
20.0m
126.7m
Gr.4L
20.0m
144.8m
Gr2_キャニスター③
167.7m
34.2m
20.0m
117.2m
120.2m
153.9m
Gr3_ドラム缶①
Gr3_ドラム缶②
20.0m
44.1m
167.7m
Gr3_ドラム缶②
20.0m
20.0m 14.0m
5.0m 11.0m
Gr4L_角型容器
Gr4H_ハル缶・インナーバレル①
139.0m
Gr3_ドラム缶①
20.0m
157.6m
Gr1_ドラム缶
Gr.2
20.0m
Gr4H_ハル缶・インナーバレル②
Gr4H_ハル缶・インナーバレル①
139.0m
Gr3_ドラム缶①
20.0m 14.0m
5.0m 11.0m
Gr4H_ドラム缶
Gr.4H
461.5m
82.0m
110.3m
Gr4L_ドラム缶②
44.1m
Gr4H_ドラム缶
Gr.4L
20.0m
Gr4L_角型容器
461.5m
Gr.4L
139.0m
Gr3_ドラム缶②
727.9m
Gr.4H
129.8m
20.0m
Gr.4H
139.0m
Gr3_ドラム缶②
20.0m
122.3m
Gr3_ドラム缶③
Gr4H_ハル缶・インナーバレル②
Gr3_ドラム缶③
Gr4H_ハル缶・インナーバレル②
Gr4H_ハル缶・インナーバレル②
Neogene sedimentary rock
20.0m
185.8m
立坑
157.6m
Gr1_ドラム缶
Gr.1
48.8m
20.0m
20.0m
立坑
727.9m
Gr2_キャニスター④
Hydraulic gradient
37.5m
Gr.2
Gr2_キャニスター⑥
20.0m
140.1m
187.1m
20.0m
Gr2_キャニスター③
187.1m
185.8m
20.0m
20.0m
Gr2_キャニスター②
Gr2_キャニスター⑤
20.0m
187.1m
Gr2_キャニスター①
20.0m
185.8m
アクセス斜坑へ
立坑
Gr2_キャニスター④
Gr.1
187.1m
立坑
20.0m
187.1m
Gr1_ドラム缶
48.8m
20.0m
20.0m
43.7m
Gr2_キャニスター③
アクセス斜坑へ
187.1m
20.0m
187.1m
20.0m
Gr2_キャニスター②
Gr2_キャニスター①
 Considering the maximum temperature of cement (80°C) and buffer (100°C)
 High-heating waste and low-heating waste are placed alternatively
 High radioactive waste (Gr.1, 2) is placed upper than other groups to make the flow
distance of nuclides longer
 Nitrate (Gr. 3) is isolated
立坑
立坑
20.0m
187.1m
Gr1_ドラム缶
48.8m
20.0m
43.7m
アクセス斜坑へ
P.39
RD&D of retrievability technology by RWMC



The retrieval procedure: (1) Remove the plug and excavate the
backfill in the disposal tunnel, (2) Remove the bentonite buffer (3)
Retrieve the overpack.
The key issues is how to remove the bentonite buffer without
mechanical damage to the overpack.
“Over-coring” and “salt-extraction” technologies were considered
and the latter demonstrated at full scale.
Overpack
“Salt-extraction” by
flushing with brine.
The surface of EBS after removing the
slurry containing the extracted buffer.
P.40
Ch.5 Assessment of pre-closure safety
【Top level key statements】
 Radiological protection during waste handling in surface facilities
assures expected exposure of nearby residents considerably
lower than the provisional dose criterion considered.
 On the basis of thermal and mechanical durability assessment of
waste packages, there would be no radiological risk to such
residents from credible accident situations, such as drops or fires.
P.41
Framework of the operational safety under the normal operation
Requirements aiming to ensure safety under the normal
operation, are the same as the common nuclear facilities.
Functional requirements
Note
Leaching of radioactive substances from
Restricting leaching from waste
the waste form will be restricted during
form
operation
Containment
Restricting release of
Release of radioactive substances from
radioactive substances from the the disposal facility will be restricted during
reception/inspection facility
waste reception and inspection
Radiation shielding
Radiation
control
Spatial dose rate from the waste form will
be decreased by shielding
Setting the radiation controlled
zone
The radiation controlled zone will be set up
Radiation monitoring and
radiation control of workers
Radiation control of workers and radiation
monitoring will be carried out in the
radiation controlled zone
P.42
Incident situations
Incident situations in the surface facilities, such as the waste
inspection facility, are similar to those in other nuclear facilities,
while those for the underground facility are specific to geological
disposal. Incident situations are addressed based on an event
sequence analysis as follows:
•
•
•
•
•
•
•
•
Dropping the waste form/overpack during handling (surface/underground)
Loss of electric power (surface/underground)
Fire (surface/underground)
Collision of transporter vehicle or deposition machine with tunnel wall
(underground)
Rock-fall (underground)
Explosion (surface/underground)
Flooding of tunnels (underground)
Flooding of the surface facilities (surface)
P.43
Safety measures for incident situations
Event sequence diagram (generic model)
Natural hazards/human or device factors
Safety measures
(e.g. earthquake, tsunami, volcanic activity, flood, typhoon,
human error, etc.)
Measures for the prevention
of incident situations
Incident situations
(e.g. dropping the waste form, fire, power cut, collision, etc.)
Measures for preventing the
propagation of incidents
Incident situations
Physical/thermal impact on the waste form
Resistant properties of the
waste form/overpack
Accident situations
Failure of radiological protection
Terminology:
Incident situation: the situation is abnormal, but direct harm to humans is not expected
Accident situation: the situation could cause harm to humans if allowed to develop further
P.44
Durability of the overpack against incident situations
The physical impacts on the metal overpack was evaluated by elastic-plastic strain
analysis. The elevation of temperature due to fire is also evaluated by modeling the
flame and thermal conductivity analysis.
Physical impact
 Case I: Collision of the transporter vehicle with the tunnel wall in the access
ramp
 Case II: Dropping the overpack onto the bottom of the disposal pit during
deposition
 Case III: Collision of the overpack with the tunnel wall due to methane gas
explosion
Thermal impact
 Case IV: Fire from a transporter vehicle
P.45
The limit of collision velocity which may cause crack penetration
We defined “failure of containment” of a metal overpack as crack penetration
through the outer to the inner surface of the overpack. The cracking was assessed
by the propagation of the equivalent plastic strain on the overpack exceeding the
strain limit of carbon steel (JIS SF340A) of 0.24 (as true strain)
Plastically deformed
but no crack penetration
最大相当塑性ひずみの発生位置
36 km/h
80 km/h
Crack penetration
最大相当塑性ひずみの発生位置
最大相当塑性ひずみの発生位置
113 km/h
最大相当塑性ひずみの発生位置
133 km/h
Crack penetration may occur when the collision velocity is over 113
km/h. (Under conservative assumption: undeformable hard floor)
P.46
Ch.6 Assessment of post-closure long-term safety
【Top level key statements】
 Post-closure safety is assessed for specific geological
environment and repository designs.
 A risk informed approach is introduced for the safety assessment.
The scenarios to be considered in the safety assessment are
classified into likely scenario, less-likely scenarios, very unlikely
scenarios and human intrusion scenarios.
 The advanced approach and methodology for radionuclide
transport modeling can be applied to compare different site and
disposal concepts.
 Since safety standard for geological disposal in Japan have not,
as yet, been defined, the results of safety assessment are
compared to international standards.
P.47
Methodology for S.A. - scenario development  Definition of “state variables”, which determine the performance of safety functions.
 Extract and structure factors that could influence state variables from the FEP
database.
Top
Down
State variable 1
Safety function of
certain component
State variable 2
Influencing factor 2-1
Influencing factor 1-1
Influencing factor 1-2
・・
・
Influencing factor 2-2
・・
・
Influencing factor 3-1
State variable 3
FEP Database
 Analyze all influence factors and extract what should be treated in S.A.s taking
into account their probability of occurrence (scenario analysis).
 Define the treatment in analysis cases for extracted influencing factors.
P.48
1D transport model for likely scenario (TRU)
Migration media
waste
Filling
(inner mortar)
waste package
Inner filling
(mortar)
Processes
（Scenario description）
Modeling
Dissolution
Constant dissolution rate (Gr.2), Instant
dissolution (the other group)
Sorption
Not considered
Confinement for some time
Sorption
Concrete cell
Permeability for short period
Buffer (Gr.1,2)
Colloid filtration, sorption,
solubility limit
Not considered
Considered
(Low heat genarating waste)
Considered for 200 years
（in case without buffer）
Considered
Backfill
Sorption
Not considered
Tunnel support
Sorption
Not considered
Rocks (near field)
Rocks (far field)
Biosphere
Dispersion, sorption
Considered for 100m
Dispersion, sorption
Considered
Sorption to soil,
dilution in surface water
Considered
P.49
Setting flow of migration parameter
Analysis of national groundwater
chemistry database
Quality check
 Migration parameter setting
Solubility
・Deeper than legal depth (-300m)
・15km far away from quaternary period
volcano
・Geology of the sampling depth is clear
Cement
Kd
Modeling of groundwater and porewater
・Model groundwater considering secondary
mineral dissolution /precipitation
・Model porewater considering buffer
interaction (ion exchange, surface complex,
dissolution/precipitation) and cement
dissolution
De
Latest sorption dataset
Buffer
Latest Ca-bentonite dataset
Rocks
Latest sorption database
Cement
Thermodynamic modeling is based on
qualified groundwater chemistry data
Thermodynamic modeling
based on porewater chemistry
Empirical formula of cracked
cement
Buffer
・Latest diffusion data
・Set for their own surface
charge (-1, 0, +1, +2)
Rock
Latest diffusion data
Setting of migration parameter
P.50
Result of dose calculation for reference case of plutonic rocks (HLW)
Dose (μSv/y)
Target dose of likely scenario: 10μSv/y
Total
I-129
Se-79
Cl-36
Mo-93
C-14
Time (y)
P.51
Result of dose calculation for reference case of plutonic rocks (TRU)
Dose (μSv/y)
Target dose of likely scenario: 10μSv/y
Total
Gr.1
Gr.2
Gr.3
Gr.4
Time (y)
P.52
Result of dose calculation for likely scenario, Neogene sedimentary rock
Dose (μSv/y)
Target dose of likely scenario: 10μSv/y
Total
Gr.1
Gr.2
Gr.3
Gr.4
Time (y)
P.53
Dose of Gr.1 for plutonic rocks
Dose (μSv/y)
Target dose of likely scenario:10μSv/y
Total
I-129
Time (y)
P.54
Dose of Gr.2, plutonic rock
Dose (μSv/y)
Target dose of likely scenario:10μSv/y
Total
C-14
I-129
Cl-36
Mo-93
Se-79
Time (y)
P.55
Dose of Gr.3, plutonic rock
Dose (μSv/y)
Target dose of likely scenario:10μSv/y
Faster release as the result of
the design without buffer
Total
I-129
C-14
Cl-36
Time (y)
P.56
Dose of Gr.4, plutonic rock
Dose (μSv/y)
Target dose of likely scenario:10μSv/y
Total
Se-79
C-14
I-129
Time (y)
P.57
Dose of Gr.1, Neogene sedimentary rock
Dose (μSv/y)
Target dose of likely scenario:10μSv/y
Total
I-129
Time (y)
P.58
Dose of Gr.2, Neogene sedimentary rock
Dose (μSv/y)
Target dose of likely scenario:10μSv/y
Total
C-14
I-129
Cl-36
Time (y)
P.59
Dose of Gr.3, Neogene sedimentary rock
Dose (μSv/y)
Target dose of likely scenario:10μSv/y
Small distribution coefficient for
rocks due to nitrate
Total
I-129
Ra-226
C-14
Time (y)
P.60
Dose of Gr.4, Neogene sedimentary rock
Dose (μSv/y)
Target dose of likely scenario:10μSv/y
Total
C-14
I-129
Se-79
Time (y)
P.61
Calculation case matched to less-likely scenarios
Uncertainties
Description of uncertainties and calculation case
Change
• Cementitious materials may make the pH of buffer porewater higher for
Cement effect to
a long time.
buffer
• Kd and De is set according to high pH condition.
• The crack may effect the permeability of concrete cell.
• The permeability coefficient of sand is used.
• Nitrate expanded to other groups as the result of heterogeneity of the
flow direction.
• The parameter is set under the nitrate concentration calculated by the
Uncertainties on analysis of plume spreading.
model
• Cementitious materials may make the pH of groundwater higher for a
long time.
• Kd and De is set according to high pH condition.
• The less-likely case of fracture network is used considering the
randomness of fracture layout.
• A hydraulic gradient may change for the future.
• The hydraulic gradient vary to the highest value after 100 thousand
years.
• Considering uncertainties on measurement of parameter
• The dispersion of dataset is assumed to be the uncertainties on
Uncertainties on measurement.
• Considering uncertainties on measurement of parameter
data
• The dispersion of dataset is assumed to be the uncertainties on
measurement.
Permeability of
concrete cell
Nitrate effect
Cement effect to
rocks
Hydraulic condition of
rocks
Hydraulic gradient
Data of buffer
Data of rocks
P.62
Results of dose calculation for less-likely scenario for plutonic rocks
likely scenario
: 10μSv/y
Reference case
Cement effect on buffer
less-likely scenarios
: 300μSv/y
Poor permeability of concrete cell
Increase the
dose of Ni-59
Nitrate effect
Cement effect on rocks
Increase the
dose of I-129
Poor hydraulic condition of rock
Large hydraulic gradient
Data uncertainties of buffer
Data uncertainties of rocks
1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03
Maximum dose (μSv/y)
P.63
Results of dose calculation for less-likely scenario for Neogene sedimentary rocks
Reference case
Cement effect on buffer
Likely scenario
: 10μSv/y
Less-likely scenarios
: 300μSv/y
Poor permeability of concrete cell
Cement effect on rocks
Poor hydraulic condition of rock
Increase the
dose of I-129
Large hydraulic gradient
Data uncertainties of buffer
Data uncertainties of rocks
1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03
Maximum dose (μSv/y)
P.64
Concept of the fault movement scenario
It is possible to identify the large fault in the site investigation step(PIA/D
Extended fault is focused on in this scenario.
Identified large scale fault
（Excluded in the repository
scale）
Concealed active
fault
Repositor
y
Regional scale
（~50 km × ~50 km）
Repository scale
（~5 km × ~5 km）
Seismogenic ground formation
P.65
Confidence in the technical feasibility of geological disposal
【Top level key statements】
 The evidence to demonstrate the feasibility of safe geological
disposal is sufficient for the next stage of site characterisation,
based on the results and discussions presented.
 Including multiple arguments, such as comparison with overseas
safety cases, natural analogues, etc., as well as demonstrated
quality assurance and knowledge management, builds
confidence in the safety case and in NUMO as the implementer.
 Future issues and updated plans are outlined.
P.66