The Determination of 226Ra in Water Samples Anil H. Thakkar & Michael Fern Eichrom Technologies, Inc. David McCurdy Duke Engineering & Services Basically this piece of work was carried for our potential client Quanterra, formerly known as IT Corp. A protocol was proposed to Quanterra based on their needs to carry out day to day analyses in their lab.

Objectives To design a procedure for radium in water which would: be a simple, short and quick procedure allow to measure Ra-226 and Ra-224 via alpha spectroscopy and Ra-228 via Ac-228 measurements eliminate the tedious steps of precipitation and metathesis An improved procedure was developed to separate Am,Pu and U in variety of water matrices.

Current Procedure Used Barium sulfate precipitation Conversion to BaCO3- tedious and time consuming

Current Procedure Used Sample + Ba carrier + Ba-133 + Conc.H2SO4_+ Heat BaSO4 Precipitate allowed to settle for several hours or overnight Precipitate collected and converted to BaCO3

New Approach Water samples Cation exchange resin column Eichrom Ln Resin column

Preparation of Water Samples 0.5 L / 1.0 L water samples Acidified to pH 2 Add 133Ba as a tracer

Eichrom Cation Exchange Column Load solution: 0.5 L/ 1.0 L of sample Rinse with 50 mL of 0.1M HNO3 Strip Ra and Ba with 100 mL of 8M HNO3

Preparation of Load Solution for Ln Resin Column Evaporate eluent from cation exchange column to dryness Dissolve residue in 10 ml of 0.095M HNO3 acid Load on Eichrom Ln Resin column

Ln Resin Column Separation (1) Load: 10 mL of 0.095M HNO3, Collect (1) and (2) for Ba & 226Ra (2) Rinse: 15 mL of 0.095M HNO3 On Uteva spec, the actinides were loaded with a load solution of 3M HNO3/0.5 M Al(NO3)3 solution, Pu was reduce by Iron. Am/Pu pass thru, Uteva, therefore the load solution and rinse are collected, Uranium is stripped by 0.01 M HCl . (3) Strip: 10 mL of 0.35M HNO3 collect (3) for 228Ac

226Ra Via Alpha Spectrometry Evaporate 226Ra/133Ba fraction to 10 mL volume Add 0.1 ml of 0.75 mg/ml barium carrier Add 3 mL of 40% sodium sulfate, 4 drops of 1:1 acetic acid. Swirl Add 0.2 mL of seeding suspension. Mix Place tubes in cold water bath for 30 minutes Filter on 0.1 micron filters, count via alpha spectrometry

eichrom 133Ba Via Gamma Counter Count 133Ba tracer yield via gamma spectrometry

228Ac Via Gas-Flow Proportional Counter Add 50 micrograms of cerium carrier Add 1.0 mL of HF Filter on 0.1 micron filters Measure for beta radiation

226Ra % Recoveries-0.5L DI Water

226Ra Alpha Spectrum

133Ba Gamma Spectrum

226Ra, 224Ra, and Daughters 224Ra 226 Ra 220Rn 218Po 222Rn

226Ra % Recoveries in Tap water

226Ra in EPA Sample Sept.18, 1998

226Ra in NJ Sample

226Ra in Georgia Inst. Of Tech. Sample# S8933

226Ra in Georgia Inst. Of Tech. Sample# WS 14776

Ca and Mg Interference 50, 100, 200, 400 and 500 ppm of Ca and Mg solutions were tested 500 mL and 100 mL volumes tested

Ca and Mg Interference in 500 mL Samples

Ca Interference in 100 mL of Sample

Detection Limits

Summary <1.0 pCi/L detection limits achievable A good replacement for BaSO4 precipitation Eliminates inconsistent metathesis steps Reduces usage of chemicals/reagents Provides consistency and saves time High amounts of Ca and Mg interferences handled well with 100 mL samples Acceptable 226Ra recoveries

Acknowledgements Special thanks to Dr. B. Parsa, New Jersey department of health, NJ Dr. B. Kahn, Georgia Institute of Technology, GA