Ranstad radiological survey Karin von Kronhelm

Transcription

1 Ranstad radiological survey Karin von Kronhelm

2 Agenda 1. Background 2. Decommissioning process 3. Measurment programme 4. Results

3 Background

4 The site in Ranstad

5 Service and process buildings within the site

6 Building for milling

7 The leaching building

8 Decommissioning process

9 Decommissioning process steps Decommissioning plan Radiological survey, phase 1 Additional measurements, as needed Clearance of materials Clearance of buildings Other business use alternatively demolition Goal In the long term the facility in Ranstad, including the remaining buildings, could continue to be used and further developed as a small scale, of the district requested, viable industrial area. The area should be adapted to its surroundings and add value to the district. In addition, it provides a natural environment that enables development of rural livelihoods.

10 Measurement programme

11 Expected nuclide inventory Ranstad the Swedish uranium mine and processing plant - Natural uranium, shale, with the whole decay chain - Chemically processed uranium with part of the decay chain broken - Uranium contaminated processing waste from nuclear fuel factories

12 Risk for radioactive contamination Risk Without risk Small risk Examples Administration building Garage Mechanical work shop Power station except bottom floor Laboratory building Waste water treatment Risk Milling building Leaching building Ion-exchange building

13 Compilation of different parts of the programme Scint i ruta SV101G12 4,50E+01 Systematical measurements Floors and walls Smear tests and scintillation measurments Ventilation Smear tests in the systems Drains Material samples in floor drains and wash basins 4,00E+01 3,50E+01 3,00E+01 Beta (cps) 2,50E+01 2,00E+01 1,50E+01 1,00E Kolumn S3 Rad S1 Scanning of loose equipment and horizontal surfaces Horizontal surfaces Smear tests and scintillation instrument Loose equipment Smear tests and scintillation instrument Complementing measurements Material samples for analysis Water samples Radon monitoring Depth of contamination Gamma spektrometric measurement/isocs Background level

14 Compilation of measured data Systematical measurements Average for each square cps alfa and cps beta/gamma Spread between min and max in a square Loose contamination, alfa och beta Content 13 buildings 510 rooms walls 434 service systems (ventilation, floor drains, wash basins) scintallation measurements smear test samples

15 Compilation of measured data, cont. Scanning Peak value cps, alfa and beta/gamma Loose contamination alfa and beta Material samples Nuclide specific activity concentration Bq/g Gamma spectrometric measurements/isocs Nuclide specific activity kbq/m 2

16 Data management

17 Results

18 Background level Measurements outside Within the facility Nearby farm Mätplats Min Max Medel Bakgrund plats 1 6,95 9,65 8,42 Bakgrund plats 2 6,20 9,65 7,02 In each building Influence of the building material Site specific influences Radon Blue concrete/light concrete Bakgrundsmätningar i byggnader inom Ranstadsverket. Byggnad Min, cps Max, cps Medel, cps Lakverket 12,00 16,9 14,0 Kontors/laboratoriebyggnaden 8,60 14,8 11,2 Sovringsverket 13,6 18,3 16,0 NVIA 6,65 10,00 8,0 Ångcentralen 8,25 11,9 10,0

19 Administration building/laboratory

20 Results from the building for milling, bottom floor

21 Depth of contamination Uppmätt aktivitet efter dammsugning, skrapning och slipning i sovringsverket. Rutans id Uppmätt medel Totalbeta cps Efter dammsugning/ skrapning Totalbeta cps SV101G Efter slipning cps Uppskattat inträngningsdjup mm 1 2 SV101G SV101G158* SV101G SV101G SV101G SVK3G SV116G SV116G SV116G SV201G SV201G SV301G * Eftersom bakgrundvärde uppmättes redan efter första dammsugningen genomfördes ingen slipning

22 Gamma spectrometric nuclide specific results Golvbrunnar Golvbrunnar/ vattenlås Golvbrunnar Golvbrunnar SV401 SV111 SV408 SV201, SV301 Golvbrunnar SV101, SV405 SV406, SV507 SV404, SV205 SV505 Bq/g Bq/g Bq/g Bq/g Bq/g K-40 3,3 E-1 <9,0E-2 4,7 E-1 4,3 E-1 6,0 E-1 Cs-137 7,2 E-2 1,1 E-2 Sönderfallskedja U-238 U-238 2,4 E0 < 8,0 E-1 1,9E0 3,0 E0 <9,9 E-1 Ra-226 5,8 E-1 9,7 E-2 1,3 E0 1,4 E0 1,3 E0 Pb-210 3,8 E-1 8,1 E-1 7,4 E-1 Sönderfallskedja U-235 U E-2 <2,3 E-2 9,2 E-2 1,3 E-1 7,2 E-2 Pa-231 <1,5 E-1 <1,9 E-1 <1,7E-1 <2,0 E-1 9,0 E-2 Ac-227 <2,4 E-2 <3,5 E-2 <3,8 E-2 6,1 E-2 4,4 E-2 Sönderfallskedja Th-232 Th-228 1,3 E-2 <9,5 E-3 2,0E-2 2,5 E-2 2,1 E-2 Ra-228 <2,5 E-2 <1,8 E-2 <2,0E-2 2,2 E-2 2,3 E-2

23 Summary With a few exceptions the radioactivity measurements are at background levels or slightly above. The number of hot spots is very limited The nuclide specific results for material samples from most buildings indicated natural uranium in equilibrium. The highest activity concentrations were found in the building for the leaching process. In the building for milling the highest activity was measured in that part of the building were the material had been handled wet. Increased activity concentrations were observed also on old process equipment. In the building for the leaching process uranium with a broken decay chain was found including low enriched uranium as well as traces of artificial nuclides. In many of the office and sanitary areas in the different buildings the measurement results were influenced by the presence of blue porous concrete in the building material. The depth of the contamination is in general very small. Exception could be were cracks have been observed, in porous material and in areas where water could have penetrated the building structures

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