Rapid method for radiostrontium determination in milk in emergency situations using PS resin

A new method based on selective fluorescent polymers (PSresin) for the analysis of 90Sr in presence of 210Pb in environmental samples

⁹⁰Sr is of major concern in emergency and environmental control plans. It is one of the main fission products in nuclear facilities and is a high-energy beta emitter that presents chemical properties similar to those of calcium. ⁹⁰Sr is commonly detected using methods based on liquid scintillation counting (LSC) following a chemical separation to remove potential interferences. However, these methods generate mixed wastes (hazardous and radioactive). In recent years, an alternative strategy using PSresins has been developed. For ⁹⁰Sr analysis with PSresins, ²¹⁰Pb is the main interferent that should be considered, as it is also strongly retained in the PSresin. In this study, a procedure was developed involving a precipitation with iodates to separate lead from strontium before the PSresin separation. Moreover, the method developed was compared with well-established and routinely used methods based on LSC, revealing that the new method produced equivalent results in less time and with less waste generation.

Simultaneous determination of 210Pb and 90Sr and 210Po isolation in sludge samples using a plastic scintillation resin

This study describes a new and fast method for separating ²¹⁰Po from ²¹⁰Pb and ⁹⁰Sr, before simultaneously measuring the individual activities of the latter two radionuclides using a plastic scintillation resin (PSresin) in sludge samples taken from a drinking water treatment plant. This method speeds up the analysis process significantly by simultaneously measuring ²¹⁰Pb and ⁹⁰Sr in a single step. The method is reproducible and has a relative standard deviation of less than 25% for ²¹⁰Pb, ²¹⁰Po and ⁹⁰Sr. The method was satisfactorily validated with an intercomparison sample and applied to sludge samples from a drinking water treatment plant. The minimum detectable activities for 0.9 g of sludge are 5.5 Bq/kg and 8 Bq/kg for ²¹⁰Pb and ⁹⁰Sr respectively when measured for 180 min, and 0.5 Bq/kg for ²¹⁰Po when measured for 5000 min.

A rapid method for analysis of non-equilibrated 90Sr/90Y in infant formula

A rapid analytical method for quantifying 90Sr in infant formula prior to secular equilibrium is presented. The approach is dependent on the use of two separations of 90Sr from 90Y, with the first providing an 90Y ingrowth start point and the second providing an 90Y ingrowth end point. Data were obtained at activity concentrations of approximately 6 Bq/kg and 160 Bq/kg, the latter of which is representative of the US Food and Drug Administration (FDA) Derived Intervention Levels (DIL). Experiments were designed to collect data from ingrowth periods ranging from 16 h to 2 weeks. Activities obtained with a separation interval as low as 16 h ranged from 92.7 to 109.4% of the known value. When 90Y ingrowth was allowed to occur for 24 h or longer, the activities ranged from 93.2 to 106.2% of the known value and the precision of this group improved from 5.2 to 3.1%. The limit of quantification (LOQ) was 0.5 Bq/kg using 250 g sample portions.

PSresin for the analysis of alpha-emitting radionuclides: Comparison of diphosphonic acid-based extractants

The analysis of radionuclides is complex, with high economic and time costs. For this reason, there is a need to develop new methods and strategies to reduce these costs. One important group in the analysis of radionuclides is the actinides, which are the main constituents assessed in the total gross alpha together with radium and radon test used to measure radioactivity in drinking water. Moreover, in nuclear dismantling processes, the possible spread of the released radionuclides has to be controlled, which is measured by many techniques, depending on the radionuclides, through scintillation. This work presents a new method to analyse actinides using plastic scintillation resins (PSresins) packed in a solid-phase extraction cartridge. The proposed method combines chemical separation and sample measurement into a single step, reducing the effort, time and reagents required for analysis as well as decreasing the amount of waste generated. The PSresins compared in this study contained three selective extractants based on methylenediphosphonic acid with different radicals, which has a high affinity for tri-, tetra-, and hexavalent actinides in dilute acids. These extractants were immobilised on plastic scintillation microspheres at a ratio of 1/1:6, producing a retention and detection efficiency of 100% for ²⁴¹Am, ²³⁰Th, Uranium and ²³⁸Pu. The retention and detection efficiency were 20% and 100%, respectively, for ²¹⁰Po and low for ²²⁶Ra.

Determination of 89Sr and 90Sr in fresh cow milk and raw urine using crystalline synthetic tunnel manganese oxides and layered metal sulfides

⁸⁹Sr and ⁹⁰Sr are both fission products of high radiotoxicity, which can be released in significant amounts in the event of a nuclear accident. Radiostrontium isotopes will follow calcium all along the food chain and, after ingestion, accumulate in the bones. Therefore, it is imperative to be able to determine ⁸⁹Sr and ⁹⁰Sr in raw milk samples in case of an accidental situation to evaluate the dose given by both radionuclides to the population. Several methods exist for conducting ⁸⁹Sr and ⁹⁰Sr determination. However, most of them use at least one chromatographic step to purify strontium. This, unfortunately, increases the analytical time before the results can be released to the authorities. In addition, they often use liquid scintillation counting to determine the ⁸⁹Sr and ⁹⁰Sr activities, a method which can handle only one sample at a time. Here we propose using synthetic tunnel manganese oxides such as cryptomelane and todorokite and layered metal sulfides to selectively extract strontium from fresh milk and raw urine in a batch sorption method. We found that the method is very quick and yields very pure sources of (radio)-strontium, which can be counted in a proportional counter. Data (counts per minute) from the counter were fitted to a mathematical expression enabling the simultaneous determination of ⁸⁹Sr and ⁹⁰Sr. Because a proportional counter often has several drawers, it is typically possible to measure up to 16 samples at a time. Since cryptomelane is a binding phase easily synthesized in a large quantity, we anticipate that this technique could be an interesting alternative to conventional solid phase extraction chromatography methods.

Evaluation of different methods for measuring 89Sr and 90Sr: Measurement uncertainty for the different methods as a function of the activity ratio

In case of a radiological emergency situation involving e.g. fission of uranium or plutonium, analysis of radioactive strontium will be of importance. The primary radionuclides of interest are ⁹⁰Sr, its progeny ⁹⁰Y and ⁸⁹Sr. A few days following an event, ⁸⁹Sr will be the predominant radioisotope of strontium. Most methods found in the literature are valid and applicable when measuring ⁹⁰Sr, but when samples contain both ⁸⁹Sr/⁹⁰Sr interference problematics arise. How these interferences are dealt with will have an effect on the uncertainty of the ⁹⁰Sr determination. This work aims at evaluating three measurement approaches, all mentioned in the literature, with respect to the measurement uncertainty when determining ⁹⁰Sr in an emergency preparedness situation and to propose a suitable measurement strategy.