Implementa)on of the Borehole Disposal Concept for Disused Sealed Radioac)ve Sources in Ghana Eric T. Glover Na)onal Radioac)ve Waste Management Centre Na)onal Nuclear Research Ins)tute Ghana Atomic Energy Commission Ghana Outline •  Introduc)on •  Regulatory Framework •  Radioac)ve Waste Management •  The borehole disposal project •  Conclusion Introduction §  The use of radioac)ve materials in Ghana began in the early 1950s in the then University of College of Gold Coast (now the University of Ghana). §  Radioac)ve sources have since been in use in various sectors of the Ghanaian economy (medicine, agriculture, industry, research and teaching) •  Ghana Atomic Energy Commission (GAEC) was established by an Act of Parliament (Act 204) in 1963 which has been superseded by Act 588 in 2000. •  The main func)ons of the Commission include the promo)on, development and peaceful applica)on of nuclear and biotechnology techniques for the beneﬁt of Ghana. Regulatory Framework Regulatory Authority •  The Radia)on Protec)on Board (RPB) is the statutory regulatory authority in Ghana that regulates all prac)ces involving radia)on and radioac)ve sources; •  The RPB was established in 1993 by PNDC Law 308; •  Draws its powers and func)ons from the Radia)on Protec)on Instrument (LI) 1559 of 1993; •  The RPB has an administra)ve and technical support unit called the RadiaCon ProtecCon InsCtute (RPI) that provides day-‐to-‐day administra)ve and technical support to the Board Radioac)ve Waste Management Infrastructure •  The Na)onal Radioac)ve Waste Management Centre (NRWMC), was established to carry out the following . ü  Management of all radioac)ve waste generated in Ghana ü  Establishment of facili)es for management of radioac)ve waste ü  Research ac)vi)es to safely manage radioac)ve waste generated in Ghana. Radioac)ve Waste Management-‐ Facility The Centralized Waste Processing facility after the upgrade will have a Ø office and laboratory Ø operational areas for segregation of the waste materials, Ø Conditioning unit Ø disused sources Ø treatment of liquid waste. The storage facility has Ø  an area for receipt of the waste, Ø  low dose storage area and Ø a high dose storage area. Ø Has physical protection systems 6 Physical Protec)on System at the Storage facility 7 Radioac)ve Waste Management Inventory Percentage genera)on by Sectors Percentage distribu)on by volume Research 9% Cd-‐109 2% Ir-‐192 2% Sr 90 13% Am 241 47% Medical 27% Cs-‐137 14% Industry 64% H-‐3 4% Co-‐60 2% C-‐14 2% In-‐113m 4% Ra-‐226 7% Cf-‐252 1% Am 241/Be 2% Borehole Disposal Project •  With increase in the genera)on of DSRS and the half-‐life of the associated radionuclides •  Long storage was considered not a sustainable op)on •  Hence the need for a disposal facility •  Considering the waste volume and form we thought of : -‐ small volume repository -‐ simple but safe technology •  The Ghana expressed the willingness to exploit the Borehole Disposal Concept developed in South Africa under the IAEA TC Project for disposal of the disused sealed sources Borehole Disposal Concept Borehole Disposal Concept Technical & Safety Aspects •  •  DSRS is sealed in a 3 mm thick 304 stainless steel capsule which is 110 mm long and 22 mm in diameter and the lid welded The capsule is then placed in a hole in a pre-‐ cast concrete in a 316L stainless steel container which is 114 mm diameter and 250 mm long Borehole Disposal Project Site Selec2on Borehole Disposal Project Geophysical InvesCgaCon and preliminary site characterizaCon •  Geophysical inves)ga)on (Seismic Refrac)on and electrical resis)vity studies) carried out suggested that; Ø the bedrock is probably gneissic or grani)c rocks Ø the bedrock rock could host a repository •  Collected data on the regional geology, hydrogeology and geochemical condi)ons and extrapolate to the site. •  Drilling was recommended to be carried out for detailed site speciﬁc geological, hydrogeological and geochemical inves)ga)on. Borehole Disposal Project Safety Assessment •  The ﬁrst itera)on safety assessment for the development of a borehole disposal facility (BDF) in Ghana was done taking into account Ø  the inventory to be disposed and Ø  the preliminary site characteris)cs. •  To iden)fy the key parameters that need to be characterised at the proposed site. •  To demonstrate and build conﬁdence in the use of narrow diameter borehole as a safe disposal op)on of disused radioac)ve sources Borehole Disposal Project Safety Assessment-cont •  Radionuclides considered are Co-‐60, Sr-‐90, Cs-‐137, Ra-‐226, Am-‐ 241 and Cf-‐252 •  An individual eﬀec)ve dose constraint of 0.3 mSvy-‐1 for adult members of the public for all poten)al future exposures •  The AMBER sobware tool was used to implement the assessment model •  TypeGeosphere – ‘Aerobic Fractured’, ‘Aerobic Porous’, ‘Anaerobic Fractured’, and ‘AnaerobicPorous’ Borehole Disposal Project Safety Assessment-‐Outcome •  Unit inventory of 1 TBq per package •  43 waste packages will be disposed, •  One borehole considered •  The total thickness of the disposal zone is 43.5 m. •  The total depth of the closure zone is 56.5m, Borehole Disposal Project Site CharacterizaCon Two exploratory boreholes ( 150m) drilled for site characteriza)on Conclusion Ø  Eﬀorts are being made to develop a comprehensive radioac)ve waste management infrastructure for safe and secure management of radioac)ve waste in Ghana. Ø  The Borehole disposal project when implemented will ensure the safe disposal of disused radioac)ve sources in the country. Ø  We are grateful to the IAEA for their assistance in the implementa)on of the Borehole Disposal project