development of the numo pre-selection, site-specific ... documents... · “the numo pre-selection,...
TRANSCRIPT
P.0
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.1
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.
Evolution of geological disposal programme in Japan
P.2
“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.
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.
Why make the NUMO Safety Case?
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
P.3
Staged site investigation process
Development of SDM
Outline of initial
repository concept
Outline of safety
assessment
Estimation of geological
environment
characteristics
Literature
Investigation Stage
Selection of PI areas
Planning of PI stage
Investigation
and
evaluation of
the
geological
environment
Repository
design
Safety
Assessment
Literature survey
Exclusion of unsuitable
sites
Preliminary
Investigation Stage
Preliminary design of
disposal facility
Understanding geological
environment
characteristics
Selection of DI areas
Planning of DI stage
Preliminary safety
assessment
Surface based
investigations
Exclusion of unsuitable
sites
Update of SDM
Detailed
Investigation stage
Basic design of disposal
facility
Detailed understanding of
geological environment
characteristics
Selection of the
repository site
Basic safety assessment
Surface based investigations
Investigations in the UIF
Confirmation that site is
suitable
Update of SDM
Development and review of the safety case
P.4
Development and review of the safety case
Development of SDM
Outline of initial
repository concept
Outline of safety
assessment
Estimation of geological
environment characteristics
Detailed
Investigation stagePreliminary
Investigation Stage
Literature
Investigation Stage
Selection of PI areas
Planning of PI stage
Literature survey
Basic design of disposal
facility
Detailed understanding of
geological environment characteristics
Selection of the
repository site
Basic safety assessment
Surface based investigations
Investigations in the UIF
Confirmation that site is
suitable
Preliminary design of
disposal facility
Understanding geological
environment characteristics
Selection of DI areas
Planning of DI stage
Preliminary safety
assessment
Surface based
investigations
Exclusion of unsuitable
sites
Exclusion of unsuitable
sites
Update of SDM Update of SDM
Development of SDM
Trial design of
repository
Next technical
development plan
Nationwide literature
Trial safety
assessment
At this stage
Setting of candidate
host rock type
The basic safety
case structure
Providing the basic safety case structure
P.5
PR materials(brochures)
Principles and safety of
geological disposal
Existence of suitable
geological environments
Safety in case of natural
hazards
Pre-closure safety
Retrievability of waste
General public
For geological
disposal experts
Reference R&D reports
NUMO-TR, JAEA-Research, CRIEPI-Reports,
Scientific papers etc.
Main Report350 pages
NUMO Safety
Case Report
Supporting ReportsDetailed background to support
the main report
178 documents, Total 4800 pages
Abridged report(Describing mainly key
messages of SC with simple
text, 50 pages)
Engineers & Technologists
Scientific communicators
For others
The geological
disposal community
Why geological disposal?
Basic concept of geological disposal
Basic Safety strategy
Stepwise approach
Reversibility
Transparency
・・・
Executive summary
30 pages
Documents and target audience
Presented using a web-based communication platform
P.6
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
Contents of NUMO Safety Case report
7
Five rock types
P.8
1 km
Active fault Active fault
Granite
Highly fractured (weathered) domain
Sedimentary overburden
100~200 m 100~200 m
GW flow
L ≥1 km
Regional scale (50 km x 50 km)
Repository scale (5 km x 5 km)
Panel scale (800 m x 800 m x 800 m)
L ≥1 km L ≥10 m
Illustrative geological setting
Fractured media
Hard rock
Nested models for plutonic rocks
P.9
Regional scale (30 km x 30 km)
Repository scale (5 km x 5 km)
Panel scale (800 m x 800 m x 800 m)
Active fault Active fault Granite Basement
Quaternary sediments (several tens of m)
Freshwater – saline water transition
GW flow
Sea
500 m
Illustrative geological setting
L ≥25 m
Nested models for Neogene sedimentary rocks
Porous media with low
density of fractures
Soft rock
P.10
1000m
Quaternary sediments (several tens of m)
Thrust Freshwater – saline water transition
GW flow
Sea
Illustrative geological setting
Regional scale (40 km x 40 km)
Repository scale (5 km x 5 km)
Panel scale (800 m x 800 m x 800 m)
Nested models for Pre-Neogene sedimentary rocks
Fractured media with
high density of fractures
Hard rock
P.11
Metal shell
Overpack Vitrified waste
Buffer
(Bentonite)
オーバーパック
緩衝材
ガラス固化体
支保工
埋め戻し材
処分孔
(処分坑道) (人工バリア)
Concrete support
Backfill
Disposal hole
Buffer
Overpack
Vitrified waste
Vertical emplacement
Backfill Concrete
support
Buffer
(Bentonite)
Waste
packages Pit
PEM
Backfill
Disposal drift
Prefabricated EBS module (PEM)
Vault waste emplacement
HLW repository TRU waste repository
(EBS)
Repository concepts to be considered in design study
P.12
予備区画
④
予備区画③
区画①
区画③
区画②
区画④
区画⑥
区画⑤
予備区画
②
予備区画
①
予備区画(TRU)
0 500m
An example of underground panel layout
Faults
(Length > 1 km)
5 k
m
Relative migration time + ‐
Unpreferable area
Short travel
time
Direction of ground water flow
Plutonic rocks model
Required scale of the facility:
Total HLW: more than 40,000
canisters of vitrified waste
Total TRU waste: more than
19,000 m3
P.13
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.
Assessment of long-term post-closure safety
P.14
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
Scenario classification and target dose
P.15
EDZ t=1000mmFracture transmissivity:100
times to the original value
Cross section
of driftShotcretet=50 mm
EDZt=500mm
Backfill (Bentonite-
sand mixture)
Buffer
Deposition hole
k=1.0×10-12 m/s
Draink=1.0×10-5 m/s
k=1.0×10-5 m/s (degraded)k=1.0×10-9 m/s
3D modeling of RN transportation
100m
10
0m
EBS
Rock
Faults and fractures are represented by stochastic modelling approaches, on the basis of the site-specific dataset obtained URLs.
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.16
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
Uncertainties in glass dissolution rate
Bentonite alteration due to Fe-silicate minerals
Uncertainties in fracture distribution
Change of magnitude of hydraulic gradient
Uncertainties in radionuclide migration parameters (Kd, De) of rock
Concealed active fault intersects the repository
Human intrusion (exploration)
Examples of safety assessment of HLW
Maximum dose rate (μSv/y)
Likely scenario
(10 μSv/y)
Less-likely scenarios
(300 μSv/y)
Human intrusion
scenarios
Very unlikely scenarios
(1~20 mSv/y)
Plutonic rock model
P.17
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…)
Progress since H12 report
P.18
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.19
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
January 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?)
Around July 2017
Schedule for the NUMO SC report
P.20
Thank you for listening