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

Thank You ! Terima Kasih !

wahab@nm.gov.my