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Radiation Protection: the experience of the Integrated Laboratory of Radioactivity Measurement and Monitoring of the ENEA Radiation Protection Institute

The ENEA Integrated Laboratory of Radioactivity Measurement and Monitoring leverages its extensive equipment and specialized expertise to perform comprehensive environmental and internal dosimetry analyses of diverse radionuclides across its centers in Saluggia, Casaccia, and Trisaia, ensuring accuracy through continuous intercalibration.

Original authors: Sandro Ridone, Dolores Arginelli, Maria Chiara Botta, Daniela Gorietti, Francesco Modestia, Davide Pirullo, Salvatore Zicari, Paolo Battisti

Published 2026-07-07

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CC BY 4.0

Original authors: Sandro Ridone, Dolores Arginelli, Maria Chiara Botta, Daniela Gorietti, Francesco Modestia, Davide Pirullo, Salvatore Zicari, Paolo Battisti

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine a team of highly skilled detectives working for a national safety agency called ENEA. Their job isn't to solve crimes, but to hunt down invisible, radioactive "suspects" that might have accidentally entered the bodies of workers or the environment. These detectives operate out of a special headquarters known as the Integrated Laboratory of Radioactivity Measurement and Monitoring.

Here is a simple breakdown of what this paper tells us about their work:

1. The Mission: Keeping a Watchful Eye

The laboratory is located in three different "bases" across Italy (Saluggia, Rome, and Rotondella). Their main goal is Radiation Protection. They act like a security system for people working with radiation. If a worker accidentally swallows or inhales a tiny bit of radioactive material, these detectives need to find it quickly to ensure the worker stays safe.

They don't just look for one type of suspect; they are experts at finding a huge variety of radioactive elements, from heavy metals like uranium and plutonium to lighter ones like tritium and carbon-14.

2. The Toolkit: How They Catch the Suspects

To find these invisible particles, the lab uses a mix of chemistry and physics, treating human waste (like urine and feces) as the "crime scene."

The "Gold Plating" Trick (Alpha Spectrometry): For heavy suspects like Plutonium and Americium, the lab takes a urine or feces sample, boils it down, and then uses a special chemical process to stick the radioactive atoms onto a silver disk, almost like plating a coin with gold. They then use a high-tech camera (alpha spectrometer) to take a picture of these atoms. This is crucial because these heavy atoms are too quiet to be heard by standard body scanners, so they must be analyzed in a sample.
The "Strontium Sieve" (Beta Counting): For Strontium-90, they use a special resin (a sticky filter) that only grabs Strontium and lets everything else pass through. Once isolated, they count how many particles are bouncing around.
The "Color Fix" (Liquid Scintillation): Urine can be yellow or cloudy, which messes up the measurement of lighter suspects like Tritium (Hydrogen-3) and Carbon-14. The lab uses activated carbon (like a giant filter) to bleach the urine clear. Then, they mix it with a special glowing liquid. When the radioactive atoms decay, they make the liquid flash. A machine counts these flashes to tell them how much radiation is there.
The "Atomic Scale" (ICP-MS): For Uranium, they use a machine that turns the sample into a super-hot gas (plasma) and separates the atoms by weight, like a super-precise scale that can weigh a single grain of sand against a mountain.

3. The "Report Card": Proving They Are the Best

Just like a student taking a test, the lab needs to prove they are accurate. They do this by participating in Intercomparison Tests (organized by a group called PROCORAD).

Imagine a master chef sends out a secret ingredient to 50 different kitchens. Each kitchen has to identify the ingredient and measure exactly how much is there. The master chef then compares everyone's results.

The Result: The ENEA lab consistently gets "Top Chef" awards (called "TOP Lab" mentions).
The Score: In most years, their measurements were off by less than 10% (often less than 5%). This means if the real amount of radiation was 100 units, they reported something very close to 100.
The Glitches: Sometimes, they had a few "bad days" where their numbers were a bit off (like 20% error). The paper explains this happened because of tricky technical issues, like the "flashes" from different atoms overlapping in the camera, or the "glowing liquid" not working perfectly. But they fixed these issues and kept improving.

4. Why This Matters

The paper concludes that this integrated lab is a unique facility in Italy. Because they have all these different tools under one roof (or across their three connected bases), they can handle any radiation safety question. They don't just guess; they have proven, over many years of testing, that their numbers are reliable.

In short: This paper is a report card showing that the ENEA radiation detectives are highly skilled, use a variety of clever chemical tricks to find invisible dangers, and have passed their "final exams" with flying colors to ensure the safety of workers and the public.

Technical Summary: Radiation Protection Experience of the ENEA Integrated Laboratory

Problem and Context
The paper addresses the critical need for accurate monitoring of internal radiation contamination in personnel working within nuclear and research environments, as well as in the general population during potential large-scale incidents. The ENEA Radiation Protection Institute (IRP) manages this through its Integrated Laboratory for Monitoring and Measurement of Radioactivity (IRP-MIR), located across three centers in Italy: Saluggia, Casaccia, and Trisaia. The core challenge lies in the precise quantification of a wide variety of radionuclides in complex biological matrices (primarily urine and feces) and environmental samples. Specific difficulties include the low-energy emissions of certain actinides requiring chemical separation, the distinction between different forms of tritium (free vs. organically bound), and the need for rapid screening capabilities during emergencies. The laboratory's mandate is to provide reliable dosimetry and technical services that meet European state-of-the-art standards and international regulatory requirements.

Methodology
The laboratory employs a suite of physical-chemical and radiochemical techniques tailored to specific radionuclides and sample types:

Actinides and Polonium (Alpha Spectrometry): For plutonium ( $^{238}\text{Pu}$ , $^{239+240}\text{Pu}$ ), americium ( $^{241}\text{Am}$ ), and polonium ( $^{210}\text{Po}$ ), the laboratory utilizes urine and fecal analysis. Samples are mineralized and solubilized, followed by separation using anion exchange chromatography with specific resins. Internal standards ( $^{242}\text{Pu}$ , $^{243}\text{Am}$ ) are used to evaluate chemical yield. The purified isotopes are electroplated and measured via high-resolution alpha spectrometry for 600,000 seconds. A specific method for $^{210}\text{Po}$ involves spontaneous deposition onto silver disks after mineralization at temperatures below 90°C.
Strontium-90 (Beta Counting): Separation of $^{90}\text{Sr}$ involves mineralization followed by extraction using a selective resin (1.0 M 4,4'(5')-di-t-butylcyclohexane[18]crown-6 in 1-octanol). The method allows for the separation of $^{90}\text{Sr}$ from its daughter $^{90}\text{Y}$ . Activity is determined either by measuring $^{90}\text{Y}$ ingrowth via Cherenkov effect or by direct beta counting of the precipitate. A rapid screening protocol for emergencies involves precipitating $^{90}\text{Sr}$ from 30 mL aliquots for simultaneous measurement of up to ten samples.
Tritium ( $^3\text{H}$ ) and Carbon-14 ( $^{14}\text{C}$ ): Both are measured using Liquid Scintillation Counting (LSC). For tritium, urine samples are decolorized with activated carbon to prevent quenching. The laboratory distinguishes between tritiated water and organically bound tritium (OBT) by separating them via distillation before counting. For $^{14}\text{C}$ , a calibration curve using quenched standards is employed to correct for efficiency loss due to urine color.
Uranium and Thorium Isotopes: Determination of $^{234}\text{U}$ , $^{235}\text{U}$ , $^{238}\text{U}$ , and $^{232}\text{Th}$ is performed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) with a Helium Collision Cell. This allows for isotopic ratio determination and quantification with very low detection limits (0.1 ppt for $^{238}\text{U}$ ). Sample pre-treatment is minimal, often requiring only dilution.

Key Contributions and Results
The paper details the laboratory's performance over a four-year period (2022–2025) through participation in international intercomparison exercises organized by the PROCORAD® Association. The results demonstrate the laboratory's competence across multiple sites and radionuclides:

Overall Performance: The laboratories received "TOP Lab" honorable mentions from PROCORAD for various analyses, including tritium, uranium, plutonium, polonium, actinides, and strontium in biological samples.
Bias Analysis:
- Actinides in Urine: Bias was generally below 10% for Saluggia and Casaccia laboratories, with isolated higher deviations attributed to spectral resolution issues.
- Actinides in Feces: Bias typically ranged between 10–15%, occasionally higher due to peak broadening affecting tracer distinction.
- Polonium: Excellent bias (0–2%) was observed in 2023, with values rising to around 10% in subsequent years, potentially linked to tracer accuracy.
- Strontium-90: The Trisaia laboratory achieved the best results with bias under 8% (mean 6%), utilizing atomic absorption for yield determination. Casaccia and Saluggia showed slightly higher bias (mean 12%), attributed to methodological differences in yield evaluation (ICP-MS vs. atomic absorption).
- Tritium: Low bias was observed for total tritium, while organically bound tritium (OBT) showed higher bias, likely due to uncertainty propagation from the subtraction method used to isolate OBT.
- Carbon-14: Bias remained low, averaging 3–4%.
- Uranium Isotopes: Bias for mass and activity determination was generally under 10%, often under 5%. Higher deviations in specific years were attributed to sample inhomogeneity but remained within acceptable Z-score limits.

Significance and Claims
The paper claims that the consistent satisfactory results in proficiency tests validate the competence, accuracy, and reliability of the IRP-MIR laboratories. The authors emphasize that these intercomparison exercises serve as a mechanism for continuous improvement, helping to identify areas for optimizing sample preparation and treatment. The significance of this work lies in the establishment of the IRP-MIR as a unique facility in Italy capable of satisfying diverse needs for radioactivity measurement and control. By maintaining high standards and reducing measurement uncertainties, the laboratory ensures the safety of the population and supports ENEA's strategic objectives in radiation protection, aligning with international standards set by bodies such as ICRP, ICRU, IAEA, and ISO.

1. The Mission: Keeping a Watchful Eye

2. The Toolkit: How They Catch the Suspects

3. The "Report Card": Proving They Are the Best

4. Why This Matters

Technical Summary: Radiation Protection Experience of the ENEA Integrated Laboratory

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