1. Package Receipt:
Please check the content of the package and compare it with the items listed in the Packing List. Sign and date the Packing List and send it back to IARMA via your Portal page or by email: office@iarma.co.uk.
2. Choice of Method/Procedure:
Participants may use any routine and validated method of their choice (i.e. you should not use these samples to test a new procedure). The within bottle homogeneity is assured at 5 g test portion for water samples.
3. Description of the test items:
Two different water sources were used. The first was thermal water from a single batch taken at borehole VB-4/74 (303 m) in Rimske Terme, Slovenia. This borehole taps into a steeply dipping dolomite aquifer that extends to depths greater than 1,000 m. The water emerges at 38 °C, has been extensively studied for long-term Tritium content, and shows a conductivity of 436 ± 20 μS/cm with a pH of 7.7 ± 0.2.
The second source was groundwater from the Ljubljana Marsh aquifer sourced in one batch from a well located aquifer of Ljubljansko Barje, Ljubljana’s marsh, Slovenia. This aquifer is closed on the upper side with a thick layer of impermeable clay, which was a subject of a long term monitoring study of the tritium content.
The water test items were gravimetrically spiked with known amounts of a NIST certified standard solution of tritium. After bottling, a homogeneity test showed acceptable results for within and between-bottle homogeneity.
4. Test item handling:
- Weigh the bottles and record the measured gross mass (as received with screw‑cap and labels) on the Packing List included with the test items.
- Thoroughly mix the water before transferring the contents to your distillation container or any sub-sampling.
- All results should be reported on a mass basis. It is recommended that the test item, or a part thereof taken for analysis, be measured by weight.
5. Reporting Requirements:
- Results or any correction to the results should be reported via your IARMA Portal page. User name and password were sent to each participant.
- Please report only two digits after the decimal point.
- For results reporting you may use “NR” for unreported results and “NA” for not applicable.
- Undetectable/unquantifiable activities shall be reported as “< the value of the method detection limit in TU”.
- The value of the measurement result and its combined standard uncertainty must be expressed in Tritium Units (TU).
- Uncertainty should be reported as the combined standard uncertainty (1 sigma level) where all individual sources of uncertainty have been identified and taken into account.
- All results should be decay corrected to the reference date 15 September 2025.
- After the reporting target date, participants will be asked to confirm their last set of reported results.
- The target date for result reporting is 30 of November 2025.
