Radiological risk assessment to workers of a dicalciumphosphate industry

Size: px

Start display at page:

Download "Radiological risk assessment to workers of a dicalciumphosphate industry"

Amy Rodgers
5 years ago
Views:

Radiological risk assessment to workers of a dicalciumphosphate industry 1 A. HIERRO 1,D. MULAS 1, G.TREZZI 1, N.

GARCIA- ORELLANA 1 1 D E P A R T A M E N T D E F Í S I C A & I N S T I T U T D E C I È N C I A I T E C N O L O G I A A M

0 8 1 9 3 B E L L A T E R R A ( B A R C E L O N A ), S P A I N. P H O N E N U M B E R : + 3 4 9 3 5 8 6 8 2 8 4.

1 Radiological risk assessment to workers of a dicalciumphosphate industry 1 A. HIERRO 1,D. MULAS 1, G.TREZZI 1, N. CASACUBERTA 2, V. MORENO 1, P. MASQUÉ 1, J. GARCIA- ORELLANA 1 1 D E P A R T A M E N T D E F Í S I C A & I N S T I T U T D E C I È N C I A I T E C N O L O G I A A M B I E N T A L S. U N I V E R S I T A T A U T Ò N O M A D E B A R C E L O N A B E L L A T E R R A ( B A R C E L O N A ), S P A I N. P H O N E N U M B E R : E M A I L : A L M U D E N A. H I E R R U A B. C A T 2 E T H - Z U R I C H, L A B O R A T O R Y O F I O N B E A M P H Y S I C S, H P K G 2 6, S C H A F M A T T S T R A S S E 2 0 C H Z U R I C H EU NORM 2 Symposium, June 2014, Prague

2 INTRODUCTION OUTLINE The phosphate industry and the Dicalcium Phosphate (DCP) production The Spanish legal framework concerning NORM AIMS OF THE STUDY DEPOSIT OF PHOSPHATE ROCK (PR) INTHEPORT OF TARRAGONA Sampling and analytical methods Principal results on dose assessment to workers DCP PRODUCTION PLANT Sampling Principal results on dose assessment to workers CONCLUSIONS 2

3 INTRODUCTION European phosphate production European Phosphate Industry Map 3 Located in Flix, North East Spain (South Catalonia) 98 km from the Ebro River mouth

INTRODUCTION The production and storage of dicalcium

concentration - Increase the biological availability 4

decay chain daughters Wet process (acid leaching) Thermal

4 INTRODUCTION The production and storage of dicalcium phosphate - Extract fluorides - Rise the mineral concentration - Increase the biological availability 4 Phosphate rock (PR) Bq kg -1 of 238 U and its decay chain daughters Wet process (acid leaching) Thermal process (elemental P by furnancing) HCl DCP H 2 SO 4 H 3 PO 4 Fertilizers Feed supplements

availability 5 1000-1500 Bq kg -1 of 238 U and its decay chain daughters PR

5 INTRODUCTION The production and storage of dicalcium phosphate - Extract fluorides - Rise the mineral concentration - Increase the biological availability Bq kg -1 of 238 U and its decay chain daughters PR imported from Morocco Stored in an outdoor deposit of 3000 m 2 Transported to the DCP plant weekly

6 INTRODUCTION Spanish legal framework in NORM 6 EURATOM 29/96 RD 783/2001 RD 1439/2010 Established for the first time the need of performing studies in workplaces to determine if there exist a significant increment of the exposure to natural radioactivity to the workers and public

7 INTRODUCTION Previous studies in DCP production plant 7 Radiological characterization Characterize the raw material, products and by-products ( 226 Ra, 210 Pb and 210 Po). Assess the temporal variability. Evaluate the radionuclide fluxes ( 226 Ra, 210 Pb and 210 Po).

8 AIMS OF THE STUDY 8 to establish the radiological risks derived from the external and internal doses received for workers: PR deposit in the Port of Tarragona DCP production plant

OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA SAMPLING 9 DUST SAMPLING TOTAL DEPOSITION SAMPLING - 17 sampling points (June 2013) AIR FILTERS SAMPLING -3 weeks (from July 2013 to August 2013)

9 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA SAMPLING 9 DUST SAMPLING TOTAL DEPOSITION SAMPLING - 17 sampling points (June 2013) AIR FILTERS SAMPLING -3 weeks (from July 2013 to August 2013) -Containers of 60 L 222 Rn SAMPLING - Aerosols collected in July Radeco vacuum-pump system collecting 40 m 3 -RAD-7 system (3 cycles of 30 min) -Continuous monitoring for 95 h at R10

10 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA SAMPLING 10 EXTERNAL DOSE -Portable gamma detector (Canberra Inspector 1000)

11 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA SAMPLING 11 PR LOAD IN TRAIN WAGONS - Air filters sampling (Radeco vacuum system) - Personal Dose (Canberra Personal Dosimeters)

OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RADIOACTIVITY MEASUREMENTS 12 238 U 4.5x10 9 a 234 Th 24.1 d 234 Pa 1.18 m 234 U 2.

83 d Gamma spectrometry Coaxial HPGe detector 218 Po 3.11 m 214 Pb 26.8 m 214 Bi 19.9 m 214 Po 1.64x10-4 s 210 Pb 22.3 a 210 Bi 5.

12 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RADIOACTIVITY MEASUREMENTS U 4.5x10 9 a 234 Th 24.1 d 234 Pa 1.18 m 234 U 2.45x10 5 a 230 Th 7.54x10 4 a Alpha spectrometry (U/Th determination) UTEVA resins PIPS detectors 226 Ra 1600 a 222 Rn 3.83 d Gamma spectrometry Coaxial HPGe detector 218 Po 3.11 m 214 Pb 26.8 m 214 Bi 19.9 m 214 Po 1.64x10-4 s 210 Pb 22.3 a 210 Bi 5.01 d 210 Po d 206 Pb Alpha spectrometry ( 210 Po deposition) 210 Pb in a second analysis via 210 Po after the first analysis cleaned the original 210 Po

OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: DUST ON THE FLOOR 13 238 U in equilibrium with 226 Ra and 210 Pb (6.

13 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: DUST ON THE FLOOR U in equilibrium with 226 Ra and 210 Pb ( Bq kg -1 ) Dispersion of the PR from the storage deposit due to the wind Range of concentrations Dust on the ground is low (up to 10 g m -2 ) efficient cleaning mechanisms REDUCE THE RISK FOR WORKERS

$U (mbq L -1 ) Dissolved fraction$ $Particulate fraction C-1 N.M ± N.M N.$

14 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: ATMOSPHERIC DEPOSITION 14 C1 C5 The rainfall plays a key role in regulating the atmospheric deposition PM5 C3 Collected 5.8 L m -2 of rainfall C2 C4 Sample 238 U (mbq L -1 ) Dissolved fraction Particulate fraction C-1 N.M ± N.M N.M ± N.M C-2 N.M ± N.M 0.25 ± 0.12 C ± ± 2 C ± ± 1 C ± 0.11 N.M ± N.M

15 Snímek 14 PM5 por qué es importante lo de los 5.8 l? Pere Masqué;

16 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: AEROSOLS PARTICLES 15 Sample 238 U (mbq m -3 ) A ± 0.01 A ± 0.02 A ± 0.01 A ± 0.02 A ± 0.01 A ± 0.01

Concentrations (Bq m -3 ) 10,00 8,00 6,00 4,00 2,00 0,00 18.07.

17 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: 222 Rn IN THE AIR Bq m -3 < 10 Bq m -3 (UNSCEAR, 2000) 12, Rn Concentrations (Bq m -3 ) 10,00 8,00 6,00 4,00 2,00 0,

18 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: EXTERNAL DOSE 17 Background: μs h-1

19 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: TOTAL DOSE 18 E = E external + i ( h(g) i,inh j i,inh ) + ( h(g) j,ing j j,ing ) <1 msv y 1 i Ra (In equilibrium with daugthers) 238 U decay serie (In equilibrium with daugthers)

20 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: TOTAL DOSE 19 Effective external dose rate < msv y -1 1 (Dose equivalente factor) 9 h week µsv h -1 E inh = V t A ( DCC i,inh c i,inh ) C i(inh) = Concentration of 238 U decay serie in air (Bq m -3 ) at each sampling point (secular equilibrium with its daughters) V= Breathed rate at working place (1.2 m 3 h -1 ) t= Residence time of employees at the workplace (9 h week -1 ) DCC i(inh) = Dose conversion factor for each radionuclide (AMAD of 5µm) ( 238 U, 234 U, 230 Th, 226 Ra, 210 Po, 210 Pb) i Internal dose by inhalation < 0.01 msv y -1

21 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA E = E external + E inhalació RESULTS: TOTAL DOSE 20 Total dose to workers < 1 msv y -1

22 OUTDOOR DEPOSIT OF PR IN PORT OF TARRAGONA RESULTS: PR LOAD IN TRAIN WAGONS 21 Dosis received by workers 0 µsv in 3 hours PR LOAD IN TRAIN WAGONS Sample Internal dose by inhalation (msv y -1 ) DP DP DP-2 N.M. DP DP DP DP DP Sample Internal dose by inhalation (msv y -1 ) A A A A A A

23 DCP PRODUCTION PLANT FLUXES OF RADIONUCLIDES U: 31 ±2 230 Th: 32 ±4 226 Ra: 30 ±3 210 Pb: 34 ±4 210 Po: 33 ±5 MBq h U: 15.3 ± Th: 30.4 ± Ra: 11±1 210 Pb: 9.7 ± Po: 33 ±1 238 U: 20 ±1 230 Th: 1.3 ± Ra: 1.8 ± Pb: 26 ±2 210 Po: 1.3 ± Ra: 3.3 ± Pb: ± Po: ±0.002 Casacuberta et al. 2011

24 DCP PRODUCTION PLANT AIR FILTERS SAMPLING 23 digestors/reacto rs DCP storage area storage F3 F2 F1 Decanter s F4 DCP packaging DCP drying nº 3 DCP Truck F8 loading Laboratory and offices F5 DCP drying nº 1-2 F7 DCP Precipitation tanks F6 DCP Precipitation tanks November 2011 and March 2012

25 DCP PRODUCTION PLANT RESULTS: AIR FILTERS SAMPLING 24 F8: DCP truck load F7: Between B-18 and B-20 F6: Between Dorr-1 and Dorr-4 F5: Offices F4: Packing area 230Th 238U 210Po 210Pb F3: Unloading PR F2: Below reactor 2 F1: Stairs close to reactor (mbq m -3 )

26 DCP PRODUCTION PLANT 222 Rn SAMPLING 25 P: Passive detector (Makrofols) A: Active detector (Rad-7 and AlphaGUARD) Total : 9 indoor and 22 outdoor sites

27 Bq m Bq m Bq m -3 < 600 Bq m -3 DCP PRODUCTION PLANT RESULTS: 222 Rn MEASUREMENTS Digestors PR Storage Offices and laboratories the highest values: -at points located in indoor areas -the outdoor sampling point P15 located at the digestors outdoor area the boiling process that occur during the HCl chemical attack of the PR

DCP PRODUCTION PLANT RESULTS: EXTERNAL DOSE Ground floor 27 µsv h-1 Scrap metal area 0.14-7.

28 DCP PRODUCTION PLANT RESULTS: EXTERNAL DOSE Ground floor 27 µsv h-1 Scrap metal area μS h -1 the storage of unused pipes with ebonite and scales with high 226 Ra concentrations (100 kbq kg -1 ) Digestion area μs h -1 accumulate 226 Ra due to the scales formation Decantion area μs h Ra absorption on the ebonite that re-covers the internal part of the pipes

DCP PRODUCTION PLANT RESULTS: EXTERNAL DOSE 28 1st floor Digestion area 0.76-4.00 μs h -1 µsv h-1 0-40 40-100 100-200 200-300 300-500 500-1.000 1.

29 DCP PRODUCTION PLANT RESULTS: EXTERNAL DOSE 28 1st floor Digestion area μs h -1 µsv h Decantion area μs h -1

DCP PRODUCTION PLANT RESULTS: TOTAL DOSE (EXTERNAL DOSE) 29 Digestion & Decantation digestors/reactor sext: 0.

30 DCP PRODUCTION PLANT RESULTS: TOTAL DOSE (EXTERNAL DOSE) 29 Digestion & Decantation digestors/reactor sext: (msv y -1 ) DCP storage area DCP packaging 1 Loading& Packing storage DCP drying nº 3 digestors/reactor DCP Truck loading s ext: (Dose equivalente factor) Laboratory: digestors/reactor Laboratory ext: sand offices DCP drying nº 1-2 DCP precipitation digestors/reactor ext: s DCP Precipitation tanks digestors/reactor Decanters s DCP Precipitation tanks Mean value at each zone Hours of annual exposure at each zone

31 E inh = V t A DCP storage area DCP packaging storage DCP drying nº 3 digestors/reactor DCP Truck loading s DCP PRODUCTION PLANT RESULTS: TOTAL DOSE (INTERNAL DOSE) i Loading& Packing inh: ( DCC i,inh c i,inh ) 30 digestors/reactor Laboratory inh: sand offices DCP drying nº 1-2 digestors/reactor sinh: digestors/reactor sinh: DCP Precipitation tanks digestors/reactor Decanters s C i(inh) = the different concentrations of the radionuclides of 238 U serie in air at each zone(bq m -3 ) V= Breathed rate at working rate (1,2 m 3 h -1 ) t= Annual residence time of employees at each area Laboratory: Digestion & Decantation DCP precipitation (msv y -1 ) DCP Precipitation tanks DCC i(inh) = Dose conversion factor for each radionuclide (AMAD of 5μm) ( 238 U, 234 U, 230 Th, 226 Ra, 210 Po, 210 Pb)

32 DCP storage area DCP packaging DCP PRODUCTION PLANT RESULTS: TOTAL DOSE storage DCP drying nº 3 DCP Truck loading 31 Total dose to workers digestors/reactor Laboratory sand offices < 1 msv y -1 DCP drying nº 1-2 digestors/reactor s DCP Precipitation tanks digestors/reactor Decanters s Workers are reducing their exposure using mask in areas with dust and also limiting the time in high exposure gamma dose DCP Precipitation tanks

33 CONCLUSIONS 32 PORT OF TARRAGONA 1.There is a dispersion of the PR around the deposit that can be measured in the dust accumulated in some parts of the port. Dust accumulation is less important proportionally to the distance to the storage deposit. 2.Maintenance practices carried out in the Port, where the load of PR and the floor cleaning are done with cab loaders, are generally effective and reduce significantly the impact of the PR derived doses to workers. DCP PRODUCTION PLANT 1.The dose assessment in the DCP production plant has revealed that the highest contribution to the total dose is due to the external dose produced by the 226 Ra accumulated in pipes where doses can reach values up to 30 μsv h The locations where these higher values were obtained are characterized by low occupancy factors of workers in the plant.

34 CONCLUSIONS 33 Although the doses are lower than the limits of 1 msv y -1, the concentrations of 238 U chain are not negligible and several radioprotection norms are necessary to maintain the dose as low as possible.

35 Thank you for your attention 34 A. HIERRO 1,D. MULAS 1, G.TREZZI 1, N. CASACUBERTA 2, V. MORENO 1, P. MASQUÉ 1, J. GARCIA- ORELLANA 1 1 D E P A R T A M E N T D E F Í S I C A & I N S T I T U T D E C I È N C I A I T E C N O L O G I A A M B I E N T A L S. U N I V E R S I T A T A U T Ò N O M A D E B A R C E L O N A B E L L A T E R R A ( B A R C E L O N A ), S P A I N. P H O N E N U M B E R : E M A I L : A L M U D E N A. H I E R R U A B. C A T 2 E T H - Z U R I C H, L A B O R A T O R Y O F I O N B E A M P H Y S I C S, H P K G 2 6, S C H A F M A T T S T R A S S E 2 0 C H Z U R I C H EU NORM 2 Symposium, June 2014, Prague

RADIOACTIVITY MEASUREMENTS CAMPAIGN ON CERAMIC INDUSTRIES: RESULTS AND COMMENTS

RADIOACTIVITY MEASUREMENTS CAMPAIGN ON CERAMIC INDUSTRIES: RESULTS AND COMMENTS V. Serradell, J. Ortiz, L. Ballesteros, I. Zarza Laboratorio de Radioactividad Ambiental, Universidad Politécnica de Valencia,