Radioactive waste managment in Estonia past, present and future

Transcription

1 Radioactive waste managment in Estonia past, present and future Ivo Tatrik

2 Content 1. Status of ALARA 2. Decomission of Paldiski Former Navy Submarine Training Centre 3. Decomission of Tammiku disposal site 4. Future tasks

3 Status of A.L.A.R.A. Estonian state owned radioactive waste management agency Established 1995 for decommission and clean up of Former Nuclear Submarine Trainig centre in Paldiski Operates modern Interim Storage in Paldiski and is involved with decomission of Tammiku ne-su disposal facility Emergency response for orphan sources

4 Radioactive waste storage facilities in Estonia Paldiski site Tammiku disposal site

5 Paldiski site history, present, future Start of the building 1960 Reactor characterisrics Unit 1 Unit 2 Thermal power 70 MW 90 MW Reactor type PWR / BM-A PWR / BM-4 Encasement (submarine hull segment) diam. 7.5 m 9.5 m Enrichment of fuel (in 235 U) 20 % 20 % Total energy load [MWh] First criticality April 1968 Feb 1983 Shut down Jan 1989 Dec 1989 Refuelling 1980 never Operating time h h second load h Fuel removed and sent back to Russia

6 Reactors condition after leaving of Soviet troops The reactors are closed with the standard lid welded to the reactor body, all holes in the reactor lid were plugged with welded plugs Absorbers have been removed from filters of the 1st, 2nd and 3rd loops All the systems of the components, pipelines and tanks have been drained All pipelines connected with the system of the 1 st loop and the draining system were plugged with welded plugs High-pressure gas and air have been removed from cylinders and systems of the reactor compartments

7 Reactors condition after leaving of Soviet troops After tightness testing, the outside surfaces of the body and the bulkheads of the reactor compartment and platforms were painted Durability of the reactor compartments bodies prepared for prolonged storage is designed for maximum design earthquake of magnitude 6,7 by Richter scale

8 Reactors condition after leaving of Soviet troops The systems were drained, but not dried. The equipment, pipelines and tanks contain dead remaining water stock in the 1st, 2nd, 3rd and 4th loops amounting to about 1370 litres for unit #1 (360 litres inside the primary circuit), and 2285 litres for unit #2 (600 litres inside the primary circuit) Risk of dispersion of radioactivity during the next 50 years can not be ignored presence of water in primary and secondary systems may trigger corrosion provisions that have been made against humidity effects regarding primary circuit and reactor compartments is not sufficient there are systems arranged for checking efficiency of radioactivity confinement provisions fire risk is not minimised

9 EC Project for Evaluation of Management Routes for the Paldiski Sarcophagi Main purpose of the project was to define the most feasible rational management route for the two submarine reactors at Paldiski regarding the cost and radiological impact to the public and the environment Contractors: Technicatome, France and BNFL, UK Subcontractors: ALARA Ltd. and VNIPIET, Russia Recommended option was full dismantling after safe storage of 50 years. Improvement of sarcophagi system had to be carried out as soon as possible.

10 Decommissioning of the Liquid Waste Store ( ) Two tanks contained about 120 m 3 waste in total - Sand, gravel, ion exchange resins, evaporation concentrates, flocculation slurry, etc. - The dominating radionuclides were 137 Cs, 90 Sr and 60 Co, total activity about 225 GBq Totally 104 waste packages produced Facility demolished 2004

11 Decommissioning of the Solid Waste Storage Cell 4A, mainly plastic sheets and sacks, buckets and small cans etc, filled up to the roof of the cell. Dose rate < 20 Sv/h Cell 1, miscellaneous material, 8 steam generators and 9 control rods. Dose rate 5-9 msv/h Cell 5, 11 control rods, some lead containers with sealed sources and a pile of miscellaneous waste. Dose rate from > 10 Sv/h at the bottom of the cell to 200 msv/h at the roof level of building.

12 Installation and waste retriewal from SWS Low-pressure in-drum compactor for soft waste Two radio-operated cranes Hydraulic cutter TV cameras and monitors

13 Waste packages from SWS 76 pcs 1 m 3 concrete containers; 3 Control Rod Containers (CRC); Wall thickness = 525 mm Outer diameter = 1200 mm Height = 2000 mm Weight = 7600 kg 8 Steam generators; 67 pcs 200 l drums (later placed into concrete containers).

14 Dismantling of Liquid Waste Treatment Facility ( ) 16 x 30 m, five floors above the ground level, two below Sand filter cartridges, ion exchange columns, flocculation tanks, evaporators, etc. Six waste receiving tanks Two control tanks for purified water prior discharge

15 Interim storage in Paldiski site Built 1997, beside reactor sarcophagi nr. 2; Made from ferroconcrete, wall thickness 25 cm; overall dimensions: length 13,25 m; width 11,8 m; height 10 m; 2 sections each for 301 standard containers; 50% filled Metal and concrete containers with outer dimensions1,2x1,2x1,2 m; useful volume of container 1 m 3. Wall thickness 10 cm; Fits all generated institutional and Tammiku waste but not RC waste

16 EU Phare project Safe long-term storage of Paldiski sarcophagi and related dismantling activities. During the period there were several (non radiological) works done on the site under EU Phare project Safe long-term storage of Paldiski sarcophagi and related dismantling activities. The main objective of the project was to guarantee the safe storage of the reactor compartments for a period of at least 50 years. By that time Estonia should have radioactive waste disposal facility, which could accommodate waste arising from decommissioning of the reactor compartments (approximately m3). Sarcophagis monitoring programme installed.

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19 Future activities Site selection project for final repository Preliminary studies for decomissioning of reactor compartments (RC) Decomissioning of RC starting at least 2040

20 Operated ; Tammiku disposal site Radon type facility (near surface); For institutional waste; Solid waste storage outer dimensions 17,8 x 7,9 x 3,3 m (below ground). Contained about 110 m 3 waste. Liquid waste tank volume 600 m 3, filled capacity 200 m 3 ;

21 Decomission of liquid waste storage (2001) Approximately 200 m 3 of liquid waste; Solid material filtered out; Radiological and chemical tests: - main isotopes C-14 and H-3; - activity of isotopes below recommended clearance levels; - chemical composition and concentration suitable for free release Decision: release to Baltic Sea after recieving licence from regulatory body; Sludge fixed in concrete; Tank demolished

22 Reasons for solid waste storage decomission Study from University of Tartu demonstrated future problems if situation stays as it is (2002); - both in farm and road construction scenarios indicated possible accumulated effective doses will exceed up to two magnitudes (250 msv/y and 26 msv/y respectivly) of maximum allowed doses (0,3 msv/y) To avoid future problems and fulfil international requirements it was decided disposal wault should be emptied and demolished; EU membership; With the help of Swedish radwaste managment company SKB were estimated possible options for waste retrieval (2005); 4 options were considered. Selected one was retrieval of waste and temporary packing on site, transport to Paldiski site and sorting and final packaging in Paldiski site.

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24 Challenges in Tammiku Estimated total activity of facility according to documents was 60 TBq (2005). Dominating radionuclides: 137 Cs, 90 Sr and 14 C. Section 6 contained 2 metal boxes with sealed sources with dose rate 1,5 Sv/h on the box surface. Based on documents 90% of facility s activity was in these boxes. Safe retrieval, packing and transport of these boxes was primary task. Other 99% of waste LLW and VLLW

25 Environmental impact asessment (EIA) was accepted in December Licence for waste removal issued in September Retrieval, packing and transport of 2 metal boxes was made in November 2008

26 LLW and VLLW will be preliminary sorted in Tammiku if possible. Complete sorting, characterization and conditioning will be made in Paldiski site where suitable facilities were built 2007.

27 Retrieval of LLW and VLLW started 2009 and will be finished 2011.

28 Waste sorting Sealed sources Compressable waste Concrete waste Contaminated wood Liquid waste Toxic waste Biological waste

29 After waste removal there is planned facility cleaning New licence needed! Facility demolishing Environmental monitoring Green field are 2015.

30 Thank You