137Cs chemical precipitation in water samples with ammonium phosphomolybdate (AMP) method and chemical yield calculation by XRF technique

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137

137Cs CHEMICAL PRECIPITATION IN _{Cs CHEMICAL PRECIPITATION IN}

WATER SAMPLES WITH AMMONIUM

PHOSPHOMOLYBDATE (AMP)

METHOD, CHEMICAL YIELD

CALCULATION AND MEASUREMENT

Asiye BAŞSARI, Aysun KAYGUN, Yusuf Z. YILMAZ, Ayhan YÜKSEL

TAEK-ÇEKMECE NUCLEAR RESEARCH AND TRAINING CENTER İSTANBUL

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137Cs in the water samples

 _{fallout after nuclear weapons tests}

 _{radioactive wastes from nuclear fuel cycle} facilities,

 _{nuclear submarines}  _{Chernobyl explosion}

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NUCLEAR WEAPON TESTS

FROM URANIUM MINING AND MILLING

223 Ra, 226 Ra, 227 Th, 230 Th, 232 Th, 222 Rn, 227 Ac, 210Pb, 210 Po 137Cs

HOSPITALS AND UNIVERSITIES

45Ca , 57 Co , 58 Co , 33 P , 51 Cr , 125I , 131I, 99mTc, 137Cs

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CHERNOBYL EXPLOSİON

CUMULATIVE AIR AND WATER EMISSIONS OF THE MAJOR RADIONUCLIDES

131I, 140Ba, 141Ce, 95Zr/95Nb, 89Sr 144Ce/144Pr, 106Ru/106Rh and 147Pm, 90Sr, 137Cs

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U-235

U-236

Cs-137 Neutron

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55 137 56 137 1 0

Cs



m

Ba



_



T_1/2=30.23 years  = 662 keV

56

137

56

137 m

_Ba

_

_Ba

_



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STUDY AREA

Sinop is one of the most beautiful natural harbors on the Black Sea Coast.

Water samples were collected twice a year during 2006, 2007 and 2008. Sampling locations were selected from the lake, the river, the sea and the drinking water.

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 15 drinking water samples

 4 lake water samples

 7 sea water samples

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MATERIALS

1-Cs Carrier Solution 2-NaOH Solution 3-Ammonium Phospho-Molybdate (AMP)

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CESIUM CARRIER

7.6 g CsCl is weighed AR grade and dissolved with 250mL double deionized water (DDW).

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NaOH SOLUTION

240 g NaOH pellets were dissolved in 1L

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AMP PREPARATION

SOLUTION A:

 Dissolve 120g molibdic acid in a mixture of

350 ml DDW and 170 mL conc. ammoniac (NH3) .

 Solution is mixed with magnetic stirrer.

 The solution is cooled to room temperature.  Add 300 mL DDW

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SOLTION B:

 60 gr NH₄OH is dissolved with 300 mL

DDW.

 This solution is mixed with about 1L

conc. H3PO4 and 120 mL conc. HNO3.  The solution is filtered.

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Solution A is heated to about 50C with

constant stirring.

Solution B is added to the solution A.

Filtered and washed the precipitate of

AMP with DDW.

AMP deposition is dried at 100 ºC for 3 or

4 h.

93gr AMP is obtained by using 100gr %85 MoO3.

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CALCULATION OF CHEMICAL YIELD of Cs PRECIPITATION

XRF SPECTROMETRY a) Precipitate is dried

b) Prepare pellets by hydrolic press.

c) Am-241 radioactive source is used to produce the characteristic K-X rays of Cs elements

d) Calcuate the chemical yield by XRF method

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before after

Cs

yield

chemical

 100



%

AAS SPECTROMETRY

a) take the water sample after and before the precipitation

procedure

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Cs-137 ACTIVITY CALCULATION time count time count cpm net cpm bgd     2 ( ) 2 ery cpm sample Net cov Re % 100  Step 1- Net cpm

Net cpm= (Gross sample cpm-bgd cpm) - reagent blank Net cpm

Step 2- 2 Value

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Kg in mass or liters in volume Sample step from sult 4 1 Re   efficiency counting step from sult % 1 5 Re  

Step 4- Correction for Volume/Mass

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T xt t o e A A  _₍₀_.₆₉₃ ₎_/ 60 1000 ) ( 6 Re 

 sult from step dpm

Step 6- Correction for Decay

Where

Ao= activity (mBq) at time of extraction At= activity (mBq) at mid-point of count

t= time (h) between extraction and mid-point of count T_1/2= half life (h)

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Error Source Value  1 Net Count Rate (cps) 0.0124 0.0003

2 Efficiency 0.032 0.006

3 Gamma emission probability 0.85 0.0030

4 Volume (L) 30 2

5 Chemical Recovery 0.65 0.02

137Cs Concentration (Bq/m3) 23.3 1.8

Reported Result = 23.3 ± 3.6 Bq /m3 (for 2)

Step 8. Uncertainity Budget:

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Step 9 Minimum Detectable Level 60 1000 ) ( ) ( 1 % 100 cov % 100 _ _ _  Kg mass or l Vol efficiency counting ery re c gravimetri mean MDL

Minimum Detectable Activity = 0.9 Bq/m3

(Calculated by the software using Curie Limit of Detection Formula)

Sample Counting Time = 180 000 seconds

Background Counting Time = 200 000 seconds

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Sampling

date Station No Sampling Depth Cs-137 Activity (Bq/m3₎

1999.05.17 43 surface 796

1999.05.13 Preila surface _988

1999.10.27 Preila surface 896

2000.06.16 Juodranke surface 633 Cs-137 activities of the surface water

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Place Year deep 137Cs (mBq/L)

Baltic Sea 1985 surface water at one station ₁₁ North Pacific

1997-1998

surface water samples at 39 stations

1.4-3.7 East Malesia 2006 surface water samples at 21 stations

1.5-3.4 Ireland Sea 2000 Monitoring of radioactivity in NW Irish Sea

water using a stationary underwater gamma-ray spectrometer at the near of

nuclear reactor 17-23

Brasil Sea Shore

2000 surface water at 5 station _{<0.12 –} 4.7 Sea of Japan 1990 Surface waters

3-5 Antarctica

1987-2001

Surface water from different points

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