Charles Grant. International Centre for Environmental and Nuclear Sciences University of the West Indies

Transcription

1 Charles Grant International Centre for Environmental and Nuclear Sciences University of the West Indies REGIONAL PRACTICAL WORKSHOP ON THE DECOMMISSIONING OF RADIOACTIVELY CONTAMINATED FACILITIES: AUGUST 2011 NECSA SOUTH AFRICA

2 1. SLOWPOKE History 2. ICENS 3. SLOWPOKE II Specs/Operation 4. Core Conversion 5. Cost Estimate 6. Conclusions 7. My expectations

3 1970 a prototype unit was designed and built at Chalk River Laboratories SLOWPOKE-1 prototype, moved to University of Toronto 1976 University of Toronto to SLOWPOKE-2 (first commercial unit, decommissioned 2001) 1976 Dalhousie University 1976 École Polytechnique core converted to LEU in Present 1978 University of Alberta SLOWPOKE Saskatchewan Research Council 1984 University of the West Indies SLOWPOKE the first low-enriched Uranium (LEU) fuelled SLOWPOKE-2 reactor was commissioned at the Royal Military College of Canada (RMC) in Kingston Scaled-up version (2-10 MWth) called SLOWPOKE-3 for district heating (shutdown in 1989) SLOWPOKE Core and Be annulus

4 Location of Remaining SLOWPOKES/MNSR

5 2. ICENS GENERAL INFORMATION ICENS located on University of the West Indies Mona Campus. Kingston Metropolitan area 28% of the islands population ~ 550k Single building divided into two wings Reinforced concrete structure with cruciform columns Building design is based on a 20 ft. x 25 ft. grid module ICENS building

6 The SLOWPOKE-2 reactor at the International Centre for Environmental and Nuclear Sciences (ICENS) formerly CNS is the only nuclear research reactor in the Caribbean. It is mainly used for Neutron Activation Analysis. The reactor achieved criticality for the first time in March

7 Geochemistry Geology National Development SLOWPOKE

8 ICENS Organizational Chart BOARD OF DIRECTORS Director General Executive Secretary Special Assistant Finance Officer Office Manager Administrative Secretary Radiation Safety Officer Senior Engineer Computer Technologist Senior Researcher/ Reactor Manager Reaearch Assitant Researcher Scientific Officer Administrative Secretary Administrative Secretary Receptionist Computer Technician Computer Technician Scientific Officer Scientific Officer Scientific Officer Scientific Officer Scientific Officer Laboratory Technician Driver Laboratory Technician Laboratory Assistants Laboratory Assistant

9 A 100 mm thick pure beryllium annulus encases the fuel cage, which is a cylinder of size 23 cm by 25 cm. The annulus acts as a side reflector for neutrons and a 50 mm thick beryllium disc forms the bottom reflector. The top reflectors, known as shims, consist of semi circular plates of beryllium each only a few millimeters thick. Since no adjustments to the core are allowed, burn-up is corrected for by the increased neutron reflection provided by adding shims as required. HEU Core Specifications Type Tank in pool Licensed 20 kw Excess 4.0 mk Fuel Extruded Moderator Light water Cooling Conduction/convection Core width 22 cm Core Height 22.1 cm Enrichment 93% U 235 Critical mass g Fuel life x 10 5 kwh

10 Core designed to have a negative temperature and void coefficient Self-limiting power Excursion maximum excess reactivity is 0.4% mk, adjusted by top beryllium reflector loading. Start-up of SLOWPOKE to preset power level is totally automatic, No automatically actuated SCRAM. Apart from manual shutdown or remote shutdown, shutdown achieved by auxiliary shutdown with cadmium capsules. The neutron flux is measured by a Reuter- Stokes self-powered cadmium flux detector with a nominal sensitivity of 1 x10-20 amps per unit flux.

11 Beryllium shim plates Reactor Container Beryllium reflectors

12 Principal Utilization of the reactor Maximum authorized power Reactor Operating schedule INAA 20kw 20 hours/ week; 40 weeks Total scheduled annual operating time Percentage of scheduled annual operating time achieved Average of operating power ~800 hours 80% 7.5 kw

13 Reactivity (mk) Reactivity Adjustments Fuel Life x 10 5 kwh Lifetime Core By agreement handling and shipping of spent fuel will be the responsibility of the Reactor Vendor/Supplier (AECL) and will be shipped back to Canada unless otherwise arranged. No spent fuel elements removed from site or discharged Changing Beryllium Reflectors ~ 5-6 years; Reactivity adjustment team June Reactivity worth of Beryllium on top relector plate 20 June 2002 June 2009 Feb 2015 Predicted next Shim Jan 1996 At current rate of use, core will remain until Dec 1988 Feb 1992 Feb 1987 Mar Thickness of Beryllium (cm)

14 1. Non-proliferation issues 2. Better performance with LEU core.

15 The conversion of the core of the SLOWPOKE reactor in Jamaica is in keeping with the spirit the global threat reduction initiative and Reduced Enrichment for Research and Test Reactors (RERTR) program. The actual core conversion for the SLOWPOKE reactor in Jamaica is to be contracted to Atomic Energy of Canada Limited (AECL). Fuel manufacture dependent on bid. Documentation for process to completed by ICENS. HEU core to sent to Savannah River for final disposal.

16 IAEA Technical cooperation Project Funding by US DOE Radiation monitoring to be provided in-house, ICENS is regional (English speaking) provider for radiation monitoring services Specifications for replacement core already exist (Ecole/RMC)

17 Comparison of HEU and LEU-fuelled reactor cores HEU-fuelled LEU-fuelled core diameter 220 mm 220 mm core height 228 mm 234 mm number of fuel pins fuel pin diameter, with cladding 5.23 mm 5.26 mm fuel length 225 mm 234 mm cladding Aluminum Zircaloy-4 fuel U-Al 28% alloy UO 2 total mass of uranium 0.9 kg 5.6 kg enrichment U % 19.89% total mass of U kg 1.12 kg volume of water in core 7.8 L 8.1 L

18 Deliverables Description Preparation Time 1 Report on adequacy of reactor site and facilities necessary to support conversion planning and preparations. 2 Report on safety and licensing documentation requirements and assessment of required updates to current documents. 3 Prepare updated regulatory requirements documents. 4* Prepare updated commissioning manual for LEU core. 5 Provide completed conversion safety analysis report to ANL staff for review and concurrence; address comments from ANL staff. 6 Provide updated operations and maintenance procedures to support LEU operations 7* Provide project quality assurance manual and other project manuals as agreed upon by ICENS and ANL staff. 8* Submit conversion safety analysis report to regulatory approval authority. 2 mos. 4 mos. 8 mos. 12 mos. 18 mos. 20 mos. 22 mos. 24 mos.

19 Image From Greg Kennedy Ecole Polytecnique

20 floor level in in. 16 in. 48 in. water level Image From Greg Kennedy Ecole Polytecnique

21 F 257 Transport Flask being put in and taken out of the reactor pool F 257 Transport Flask being prepared for fire/crush shield

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24 I-beam capacity lbs floor load capacity, 4500lbs per square inch, move the transport flask through the building using a six wheel hydraulic cart (load capacity ~8000lb), each of the 4 doorways to be passed through are 1.6m by 2.1m

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26 Item Cost US$ Preliminary planning and engineering Project management Defueling Develop defueling method Fabricate fuel cage Fabricate fuel elements Fuel loading and commissioning Lawyers, radiation safety, painting, etc LEU fuel packaging and shipping 5922 Materials Preliminary planning and engineering Prepare fuel documents Project management Purchase UO Quality assurance plan Refurbishment Safety analysis report Travel Used fuel disposal Total (estimated) Estimated cost based on Montreal conversion in 1997 corrected for inflation (41%) and devaluation of the US$, and adjustment for travel to Jamaica

27 TC (Funding provided by the DOE), Documentation Provide by ICENS / Subcontractors Defueling/Refueling preferably contracted to AECL Legislation moving in the right direction No major legal or physical obstacles A firm timetable only when LEU fuel manufacturer has been selected Conversion process from shutdown to startup can be completed in a six week window

28 My immediate concerns are for core conversion, many similar issues as decommissioning, however disposal of radioactive and no radioactive reactor parts are not yet an issue as all auxiliary system will be reused. In the commissioning of the new core a decommissioning plan will be required, information which I can gather now for the future at which time the following procedures should be in place : Disposal of radioactive, non-radioactive reactor parts Replacement of Ion Exchange Columns Shipment of reactor core to Savannah River Controlling the ph of Reactor Vessel Water Sampling and Analysis of Pool Concrete and Rebar

29 Thank you for your attention!!