1. Determination of Sr-89/Sr-90 in primary cooling water
Steffen Happel
Nuclear Chemistry
Department of Chemistry
Philipps-University Marburg

2. Method
Extraction of Strontium by solid phase extraction (SPE) using EiChroms Sr-spec® resin (prepacked column)
Determination of Sr-89/Sr-90 by liquid scintillation counting and Cerenkov counting
Sr recovery to be determined by AAS (Sr-carrier)
Sr-90: 0.5 MeV (Cerenkov-Detection efficiency < 0.5 %)
Sr-89: 1.5 MeV
Y-90: 2.3 MeV
Y needs to be separated from Sr

3. Primary cooling water:
Variety of different radionuclides
B(OH)3 > 1000 ppm
Np/Pu Cs

4. B(OH)3 No measureable retention on Sr-spec® column
precipitation during evaporation
Removal by cation-exchange
B(OH)3 is not retained on exchange resin
sample preconcentration

5. Cs Cs is retained on Sr-spec® column (up to 1 %)
can cause interference in liquid scintillation counting
need to remove when in large excess compared to Sr
removal: precipitation by adding ammonium phosphomolybdate use of second Sr-spec™ column -ion-exchange chromatography
Horwitz et al.

6. Cs removal by ion-exchange chromatography
% of the Cs-activity is removed by washing the ion-exchange resin with 10 mL 2.5 M HNO3 and 10 mL 0.1 M HNO3
less than 10 % of the Sr-activity is removed
to be optimized
disadvantage: loss of Sr

7. Np/Pu both retained strongly under high-acid conditions
would interfere in liquid scintillation counting
can be removed by the use of oxalic acid
Horwitz et al.

8. B(OH)3-removal

9. Strontium extraction

10. LSC- Option 5 mL Aliquot + 15 mL scintillation cocktail
- total radioactive strontium
15 mL Cerenkov-counting
- Sr-89 activity
Sr-90 activity calculated by subtracting Sr-89 activity from total Sr activity
take aliquot to determine Sr-recovery (AAS)

11. Cerenkov-Option 20 mL Cerenkov counting - Sr-89 activity
take aliquot to determine Sr-recovery (AAS)
wait for sufficient Y-90 ingrowth (2-8 days)
add Y-carrier and evaporate to dryness
add 5 mL 8 M HNO3 and load on to Sr-spec® column
strip Y from column with 10 mL 8 M HNO3
submit collected eluents for Cerenkov counting
take aliquot to determine Y-recovery (AAS)

12. Comparison of Options
LSC-Option results within 1 day Sr-90 activity only few % of total Sr-activity need good calibration mixed waste (scintillation cocktail)
Cerenkov-Option no mixed waste single point calibration for Sr-89 and Y wait for Y-90 ingrowth - more accurate less interference by other radionuclides

13. Because of Y-90 ingrowth samples should be counted within 3 hours
crown-ether bled from the column causes luminescence, therefore underground counting should be done with an appropriate blank sample

14. Determination of Sr-89/90 using Sr-spec®
Sr-spec®shows high selectivity for Sr
Sr content should not exceed 5 mg per sample
easy method
need only few chemicals
no HCl used
results within 1 day (LSC-Option)
no mixed waste (Cerenkov-Option)
good Sr-recovery (about 50%)

15. EiChrom, Inc. RWE AG KKW Biblis Dr. Ralf Sudowe