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BDC Project - Malaysia Experiences
Mohd Abd Wahab Yusof Malaysian Nuclear Agency
Borehole Disposal: A Safe and Effective Endpoint for Disused Sealed Radioactive Sources Room M6, M Building IAEA Vienna 16 September 2015
BOSS was introduced in Malaysia by IAEA expert (2008) Nuclear Malaysia was given the task to study the possibility to
implement BOSS in Malaysia Proposal for the borehole project was approved by Nuclear
Malaysia’s top management in Jan 2011 Assistance from IAEA through TC Project (MAL3008,
MAL3009, MAL9013, MAL9015) 3 candidate sites identified within Nuclear Malaysia Suitable site has been chosen after the desktop & resistivity
study. MoU with Mineral and Geoscience Department
Project Background
BOREHOLE DISPOSAL CONCEPT (BDC)
Why Malaysia is Interested In Borehole Disposal Concept?
Safety - Defence in Depth Concept
1. Radioactive source – double encapsulated 2. Capsule SS316L (SS304) 3. Cement concrete 4. Disposal Container SS316L 5. Cement concrete Backfill 6. Steel casing (HDPE) 7. Cement concrete (disturbed zone backfill) 8. Geosphere/host rock (sorption)
Security
Small footprint
Easy to build – borehole technology available in Malaysia
1 • Preparatory Work : project proposal, national
inventory update, desk top study
2
• Pre-disposal Phase : Site selection, site characterisation, waste acceptance criteria, waste conditioning, site specific design, safety assessment and safety case, Licence application
3 • Disposal Phase : Construction, operating the facility,
borehole closure, rehabilitation and monitoring
What Stage is Malaysia?
DSRS INVENTORY AND CHARACTERISATION
Inventory of DSRS (1985 -2013) Category 3, 4 and 5 (1)
Radionuclides Number of sources Total Activity (GBq)
Ra-226 612 1.19E+02
Am-241 5187 4.216E+02
Am-241/Be 19 6.737E+02
Cs-137 284 5.10E+02
Sr-90 413 6.077E+01
Co-60 349 5.818E+01
Kr-85 60 4.79E+02
Fe-55 29 1.81E+00
Cd-109 32 3.83E-01
Ni-63 18 6.47E+00
Pm-147 58 2.77E+00
Tl-204 75 7.84E-04
Total 7136 2.33E+03
Inventory of DSRS (1985 -2013) Category 3, 4 and 5 (2)
characterize area work Segregation of Co60 & C137 into group
Record the detail information at each device into log book Dose inspection for each device (on surface & 1m distance)
DSRS CHARACTERIZATION
CONDITIONING OF DSRS
Conditioning Facility
Dismantling and Conditioning of DSRS
Dismantling
Remote Automatic Welding of capsule Bubble Test
Transfer capsule into Drum
Transfer of DSRS into Capsule
Siting
Siting Information
Desk Study -geology, hydrogeology, geochemistry, geomorphology, meteorology, seismic.
Geological Mapping (working together with Mineral and Geoscience Department The study area is covered by thick layer of residual soil and completely
weathered rock surface geological mapping reveals the study area is overlain by
metamorphic rocks of the Kenny Hill Formation lithology - composed of psammitic schist of sandstone origin and phyllite
Seismic Study - seismic and tsunami risk in Malaysia 2006 and seismic threats 2008
Resistivity Study - profile of 80m depth subsurface geology obtained for the potential site
Work was commenced on 21st Oct 2013 for a duration of 6 weeks.
One number of borehole has been drilled Detailed site characterization-geology,
geochemistry, hydrogeology
Site Characterization (1) First Investigation Borehole – 100m
Hydrogeological Data
Hydraulic conductivity; Hydraulic gradient; Porosity
Geochemical Data
pH, Eh; Chloride; Sulphate; Total inorganic carbon, Kd value, chemical species present
Geology Information
Soil type, Rock Type Rock strength
Site Characterization (2) Second Investigation Borehole – 200m
Drilling Rock core
Gamma Log
PRELIMINARY SAFETY ASSESSMENT
Safety Assessment
1. Radioactive source – double encapsulated ×
2. Capsule SS316L (IAEA/NECSA -SS304) √
3. Cement concrete √ 4. Disposal Container SS316L √ 5. Cement concrete √ 6. Steel casing (or HDPE) √ 7. Cement concrete (disturbed zone
backfill) √ 8. Geosphere/host rock (sorption) √
• The groundwater existing in the borehole is slightly acidic and therefore creating a slight reducing environment in the borehole.
• The host environment comprised of weathered zone and therefore is porous • Water table appears at 30 m
Reference case
Sketch of the Conceptual Site Model of BDC
• The scenario attributes for the SA context is that the migration of radionuclides and discharge of groundwater to the Semenyih River.
• The discharge to the water course will likely to be as the source of uptake as drinking water and also be used for watering crops.
• As the scenario involves groundwater release, hence radon diffusion is not an issue since it is a saturated zone.
• Dose constraint is 0.3 mSv/y
CSM involving discharge to the river CSM involving discharge to the stream leading to the river.
Amber- Conceptual Site Model
Design Scenario (Surface Water Scenario): Reference case assumes discharge to a river to the south of the site
(1300m from borehole) high geosphere flow rate to river high geosphere flow rate to stream to the west of the site
Well Scenario: 10m from the disposal borehole 50m from the disposal borehole 100 m from the disposal borehole 400 m from the disposal borehole 1000 m from the disposal borehole
Defect scenario Preliminary assessment showed that doses were below the dose criterion,
0.3mSv/y for all scenarios.
AMBER Calculation Cases
Capsule and Disposal Container Design
Capsule
Capsule size: Ø: 52mm L : 150mm T :5mm
Disposal Container
Container size: Ø: 114mm L: 250mm T: 11.74mm
Pneumatic Grabber and Borehole Camera
Pneumatic Grabber Borehole Camera
Alignment Test
Remote Welder
Welding Equipment for Capsule
Performance of welding
DSRS conditioning – Will proceed with IAEA expert expected in November 2015 and will continue by Nuclear Malaysia staff
Finalising welding programme for disposal container – using IAEA or Nuclear Malaysia welding machine
Demonstration borehole Preparation of Final Report for Safety Case and Safety
Assessment Report Licensing process Construction of disposal borehole Operation of disposal borehole Stakeholder programme
Present and Future works
DSRS dimension– old sources - some sources cannot be found in IAEA inventory (International Catalogue of Sealed Radioactive Sources and Devices (ICSRS)
Differences in experts opinion – you need to decide No experience from other country Equipment – everything new, need to be designed and
manufactured by our workshop Design of the disposal container Transfer cast or mobile hot cell – IAEA or Nuclear Malaysia? Design of disposal borehole – cost and differences in opinions Construction of disposal borehole Disposal of sources into disposal borehole Preparation of safety case and safety assessment Quality of welding – qualified welder, welding machine Stakeholder programme Licensing
Issues and Challenges
Transfer Cast Design Disposal Container Disposal Design
Issues and Challenges
Welding Technology
Welding Machine Welding quality
Licensing Process • Gathering enough
information for safety case
• To convince the regulatory body
• To convince stakeholders
Issues and Challenges
Design of Disposal Borehole – which one
Precast
Stakeholder Awareness
