Optimizing Radiochemical Methods at SRS

Sherrod L. Maxwell, III

Westinghouse Savannah River Company

Recent Improvements

• SRS Environmental Monitoring lab– new actinide methods for water, air filters, soil,

sediments, sanitary sludge

• SRS Bioassay lab (with Dave Fauth)• increased Pu-Np recoveries

• faster fecal method (HEDPA-no microwave)

• F/H Laboratory (Process lab)• faster single column separation for Pu/Np in high U

samples (U-234 removal of 1E6)

SRS Environmental Monitoring Lab

• Stacked TEVA + TRU cartridges for all matrices• Replaced UTEVA+TRU

– water samples

– air filter samples

– soil, sediments (up to 10 grams)

– sanitary waste sludge (5 grams)

– vegetation (10 grams)

– fruit (100 grams)

Advantages of TEVA+TRU

– Pu, Np, Am, Cm, U (Th) in a single stacked column

– Allows Pu and Np together on TEVA (Pu-236 tracer)

– High retention of Pu, Np on TEVA

– Higher retention of U on TRU vs. UTEVA

– Better Po-210 removal (interferes with U-232) and Th removal

• Removal of TEVA/removal on TRU if any residual

Pu, Np, Am, Cm,U, Sr on TEVA/TRU RESIN (Water/Air filters)

Rinse20 mL 3MHN03

Th Elution20mL 9MHCI

Pu, Np Elution20mL

0.10MHC1 - 0.05MHF - 0.03M TiCl3

1) Redissolve in 10-15 mL 3M HN03 - 0.5M to 1M Al(NO3)3

2) Add 0.5 mL 1.5M Sulfamic Acid + 1 mL 1.5M Ascorbic Acid3) Add 1 mL 3 M Sodium Nitrite

Remove TRU cartridge:1) Elute Am with

15mL 4M HCI2) 10 mL 4MHCL-0.2M HF to remove any Th2) Elute U with

15mL 0.1M ammonium

bioxalate

2mL TEVA Resin(50-100 um)

2.0mL TRU-Resin(50-100 um)

Collect, evaporate, dissolve in 8M HNO3Sr Resin

Alpha spectrometry

Cerium fluoride

Add 0.5 mL 30 wt% H2O2

Alpha Resolution Improvements

• Strong HCL can cause extractant bleed-off • TEVA: 5 mL 3M HNO3 rinse after 9M HCL Th removal

rinse prior to stripping Pu and Np • TRU:

– 4M HCL extractant bleed-off affects resolution (worse with 9M)

• We have gone back to evaporating 4M HCl with con HNO3 and 100 uL of 1.8M H2SO4, then ash with con HNO3 and H2O2, redissolve in 0.5M HCL

– 3M HNO3 rinse after 4M HCl-0.2M HF rinse• UTEVA/TRU:

– Using 9M HCl with UTEVA or TRU can affect bleed-off and peak resolution/not needed

Total DissolutionSoil, Sediments, Sludge

• Actinides in soil, sediment and sanitary sludge samples – 5 to 10 gram soil – 5 gram sanitary sludge– Replaced fusion method which had poor recoveries,

load solution problems, and Po-210 problems

• Total Dissolution– sodium peroxide/sodium hydroxide fusion (15-20

minutes)– multiple samples fused at once in furnace– inexpensive zirconium crucibles

Total DissolutionSoil, Sediments, Sludge, contd.

• Total Dissolution and matrix removal (1 day)– soils: heat at 550C, then nitric acid/HF silicon removal

first, then fusion

– sanitary sludge: heat at 550C, then fusion

– fusion in zirconium crucibles for 20 minutes at 700C

• 10 grams sodium peroxide/5 grams sodium hydroxide

– Hydroxide precipitation with TiCl3 reductant and barium present to eliminate carbonate interference

Total DissolutionSoil, Sediments, Sludge, contd.

– Redissolve in dilute HCl and perform cerium fluoride precipitation (500 ug to 2 mg Ce) with TiCl3 present

– Rinse precipitate with 0.25M HCl- 6MHF with 0.02M rongalite present

– Soil load solution: 5 mLs 3M HNO3-0.25M boric acid, 6 mL 7M HNO3, 7.5 mL 2M AL(NO3)3

Transfer to crucible after silicon removal

10 grams sodium peroxide + 5 grams sodium hydroxide

700C for 20 minutes

Just add water after cooling briefly

Dilute to 1 liter with water with iron carrier, TiCl3, and barium present

After centrifuging, acidify and add TiCl3, Ce and HF.

Place on ice, then centrifuge

Rinse with dilute HCl, HF with rongalite present

Redissolve in acid, boric acid and aluminum nitrate

Actinides in SOIL

RinseBeaker rinse: 3mL 5MHN03

Separate cartridges:TEVA: 5 mL 3MHN03 Collect/acidify - with 2 mL16M HN03 then to TRUTEVA:10 mL5M HNO3

8 mL3M HN03

Th Elution20mL 9MHCI

Pu Elution20mL

0.10MHC1 - 0.05MHF - 0.03M TiCl3

1) Redissolve in 18.5 mL 3M HN03 - 0.8M Al(NO3)3- 0.07M boric acid

2) Add 0.5 mL 1.5M Sulfamic Acid + 1.25 mL 1.5M Ascorbic Acid3) Add 1 mL 3 M Sodium Nitrite

Remove TRU cartridge:

1) Elute Am with 15mL 4M HCI2) Add 3M HNO3 rinse from TEVA3) 10 mL 6M HNO3 -remove any Po-210 4) 15 mL 4M HCl-0.2M HF-remove Th5) Elute U with 15mL 0.1M ammonium bioxalate

2mL TEVA Resin(50-100 um)

2.0mL TRU-Resin(50-100 um)

Cerium fluoride / Alpha spectrometry

Alpha spectrometry

Cerium fluoride

Add 0.5 mL 30 wt% H2O2

Am/RE Removal on TEVA

Rinse

Beaker rinse: 3mL 4M NH4SCN, warm

10 mL 1.5 M NH4SCN to column

Am Elution25 mL 1M HCl

(warm and rinse original beaker)

1) Evaporate 4M HCl with 5mL con.HNO3, 50 uL of 1.8M H2SO4, then ash with nitric acid and hydrogen peroxide2) Redissolve in 5 mL of 4M NH4SCN, warm gently.

2mL TEVA Resin(50-100 um)

Alpha spectrometry

Cerium fluoride

Final Am Clean-up on TEVA

QAP 0903-SOILSRS EML Ratio

Pu-238 14.9 14.6 1.021Pu-239 31.6 30.4 1.039Am-241 18.3 18.4 0.995U-234 117.7 127.3 0.925U-238 119.9 127.1 0.943

Results in Bq/kg5 gram sample analyzed

Bioassay Lab Improvements

• Actinides and Sr-90 in urine– stacked TEVA+TRU Resin cartridges with vacuum boxes

– Pu-236 tracer for Pu and Np at same time

– Pu, Np (TEVA) and U, Am (TRU)

– Sr (Sr Resin)

• Pu stripping improvement:– Increased rongalite to 0.04M (sodium formaldehyde sulfoxylate) -

– compatible with electroplating

– adjust bisulfate added for sulfate added from rongalite decomposition (2.0 mLs 10 % bisulfate instead of 3 mLs)

Bioassay Lab Urine MethodTracer Recoveries

2002 2003 2004Pu 77.5 86.1 95.1EU 80.6 83.4 87.4Sr 82.7 80.1 82.2Am 83.5 84.3 80.5Np 76.6 87.1 94.4

Recent Improvements in Fecal Method

– HEDPA strip of Diphonix instead of microwave destruction (18 mL 0.5M HEDPA)

– 45 minute hot plate destruction• 30 mL of 30 wt% H2O2• Add 200 uL of 1.5M ferrous sulfate• 1 mL of concentrated HNO3• Ash to dryness• Add 5 mL concentrated HNO3, ash to dryness• Add 5 mL 30 wt% H2O2, ash to dryness. Repeat 3

more times.• Faster than microwave, but requires more aluminum

in load solution due to higher phosphate

Process Lab Improvements

• Process samples to support HEU Blenddown processing– Pu and Np are key product specification measurements

– Pu-236 tracer for Pu and Np on TEVA resin in HEU and LEU process solutions

• Improvements:– Single cartridge instead of two column method

– use Ti (III) reductant in Pu strip from TEVA

– Using 0.5mL 30wt% H2O2 instead of nitrite, much better oxidation of U+4 to U+6

– 1000 x removal of residual U in cerium fluoride precipitation

– $100K savings-labor and materials

Summary

• SRS Environmental Monitoring lab work– TEVA+TRU for all matrices– Cerium fluoride matrix elimination

• Bioassay lab– Improved Pu stripping using rongalite (95% recoveries)– HEDPA to eliminate microwave in fecal analysis (save 1-2 days)

• Process lab– Single cartridge separation for Pu, Np in process lab on high

uranium samples (cost/time savings)

• Future work– Ra on MnO2 resin

MnO2 Resin