🌿 Determination of the activity concentration of gamma-emitting radionuclides with energies of 40 keV–2 MeV in water by high-resolution gamma-ray spectrometry (according to the generic method of ISO 20042) — a sample of drinking water, rainwater, surface water, groundwater, cooling water, industrial water or wastewater (homogeneous, filtered if necessary) is measured directly in a container (e.g. a Marinelli beaker) or after concentration by evaporation, with energy and efficiency calibration (standard sources or numerical Monte Carlo methods), corrections for dead time, pile-up and coincidence summing; result in Bq/l with uncertainty, decision threshold and detection limit according to ISO 11929; without concentration about 5·10⁻² Bq/l for 137Cs, PN-EN ISO 10703

Environment PN-EN ISO 10703

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in two iTeh samples of ISO 10703:2021 (third edition of June 2021): SIST EN ISO 10703:2021 (English text) — title page, contents, foreword with changes and introduction, up to page vii; ISO 10703:2021 in the French version — contents, foreword, introduction and Clauses 1–4 and the beginning of Clause 5 (principle) — the sample breaks off on page 4. We do not read the standards (6), reagents (7), apparatus (8), nuclear data (9), sampling (10), procedure (11), calculation, uncertainty, decision threshold and detection limit (12), test report (13) or Annexes A–C; we know the titles from the contents.

ACCORDING TO THE TEXT OF ISO 10703:2021. The standard was prepared by ISO/TC 147 “Water quality”, Subcommittee SC 3 “Radioactivity measurements”, in collaboration with CEN/TC 230 “Water analysis” (Vienna Agreement). The third edition cancels and replaces ISO 10703:2007, technically revised; main changes according to the foreword: a new common introduction; scope extended to emergency situations and wastewater, upper limit of dead time raised to 10 %; sample storage in accordance with ISO 5667-3 (Clause 10); change of the calibration standard source (6.2); efficiency determination by the Monte Carlo method (11.2.3); completely changed rules on pile-up and dead time and on coincidence summing (12.1.4); a correction factor for dead time and pile-up added (12.1.2); the shortest coverage interval according to the new ISO 11929 series (12.5.2); change of the test report (13). Introduction: water contains natural radionuclides (40K, 3H, 14C, the thorium and uranium series — 226Ra, 228Ra, 234U, 238U, 210Pb) and artificial ones (transuranium elements, 3H, 14C, 90Sr, gamma emitters) from fuel cycle facilities, medical and industrial uses, fallout from nuclear explosions and the Chernobyl and Fukushima accidents; national regulations set limits for effluents and guidance levels for water and drinking water; for example, according to WHO guidelines for planned or existing situations the guidance level in drinking water is 10 Bq/l for 134/137Cs and 131I, 1 Bq/l for 241Am and 0,1 Bq/l for 210Pb (Note 1: with consumption of 2 l/d for a year this gives an effective dose of 0,1 mSv/a); in an emergency situation the Codex levels for infant food are 1000 Bq/kg 134/137Cs, 100 Bq/kg 131I, 1 Bq/kg 241Am, and for other food 1000, 100 and 10 Bq/kg (Note 2: they apply to food as prepared for consumption, with an exemption level of 1 mSv per year); the method can be adapted so that the characteristic limits allow a result below the required level to be demonstrated; it can be used for effluents before storage and discharges before release; in planned, existing and emergency situations, and for wastewater with modifications that may increase uncertainty, detection limit and threshold; for samples after proper sampling and preparation (ISO 5667 series); it meets the need of laboratories that may require accreditation for radionuclide measurements in drinking water. Scope (1): physical treatment and conditioning of water samples and determination of the activity concentration of gamma-emitting radionuclides with energies of 40 keV–2 MeV by gamma-ray spectrometry according to the generic method of ISO 20042; for drinking water, rainwater, surface water, groundwater, cooling water, industrial water and domestic and industrial wastewater, after proper sampling and preparation (filtration if necessary, taking into account the amount of dissolved matter); only homogeneous samples or samples homogeneous after filtration; lower limit without concentration and with passive shielding only — about 5·10⁻² Bq/l for 137Cs (footnote: 3 l Marinelli beaker, N-type HPGe detector of 55 % relative efficiency, counting time 18 h); upper activity limit corresponds to a dead time of 10 % — higher acceptable when the correctness of the correction has been shown; below 5·10⁻² Bq/l concentration by evaporation may be needed, during which volatile radionuclides (e.g. radon, radioiodine) may be lost; the method is suitable for emergency situations. References (2): ISO 3696, ISO 5667-1, -3, -10 and -14, ISO/IEC 17025, ISO 80000-10. Definitions (3): blank sample — a container identical to that for the sample, with demineralized water; dead time in percent — (real time − live time)/real time × 100; dead-time correction; decay constant, T1/2 = ln(2)/λ; counting efficiency — ratio of photons recorded in the full-energy peak to photons emitted; resolution (FWHM); full-energy peak; gamma cascade; pile-up — counting of several simultaneous absorptions as one; transition probability. Symbols (4): e.g. sample volume V in litres, counting times of sample, background and calibration, correction factors for decay, coincidence losses, summing and dead time with pile-up, expanded uncertainty U at k = 2, decision threshold, detection limit, limits of the symmetric and shortest interval, in Bq·l⁻¹. Principle (5, beginning): gamma radiation produces electron–hole pairs in a semiconductor detector, recorded after amplification as electrical pulses with an amplitude depending on the photon energy.

STATUS (as of 03.10.2026). In the PKN search (term “10703”, 03.10.2026) PN-EN ISO 10703:2021-12 (English version) has no withdrawal note; PN-ISO 10703:2002 — “Withdrawn and replaced by PN-EN ISO 10703:2016-01”. Card of PN-EN ISO 10703:2021-12: publication date 16.12.2021, 42 pages, KT 246 Radiological Protection, ICS 17.240 and 13.060.60, introduces EN ISO 10703:2021 and ISO 10703:2021, “Replaces PN-EN ISO 10703:2016-01 – English version”, no withdrawal note. In the iTeh catalogue (read 03.10.2026) ISO 10703:2021 has the status “Published”, stage 90.60 (close of review).

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read 03.10.2026). The number 10703 appears in 3 records at 3 laboratories: AB 377, AB 435, AB 519. In the current PCA documents (read 03.10.2026; AB 519 issue No. 26 of 26.11.2025, AB 377 issue No. 29 of 12.12.2025, AB 435 issue No. 32 of 19.05.2026) the number appears in 3 lines at the same 3 laboratories; in each document the number of page markers equals the number of PDF pages, without repetitions; a search of all PCA documents downloaded from the BIP on 03.10.2026 found no laboratories outside the database copy. The form is always “PN-EN ISO 10703:2021-12”, at AB 519 together with PN-EN ISO 20042:2022-01. None of these items is suspended. The “Laboratories” tab (term “PN-EN ISO 10703”) shows all 3 laboratories — checked by a tab query on the labcoda.pl production server on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). Object: water and water intended for human consumption (AB 377, AB 435), water, surface water and water for human consumption (AB 519). Characteristic: activity concentration of the radionuclide 137Cs. Ranges: (0,1–10 000) Bq/kg and (0,1–10 000) Bq/l (AB 377, AB 435); (0,1–1500) Bq/dm³ and (0,1–1500) Bq/kg (AB 519). Technique: gamma-ray spectrometry.

WHERE AN APPARENTLY CORRECT RESULT IS EASY TO GET. With the lower limit: about 5·10⁻² Bq/l for 137Cs without concentration applies to a specific set-up (3 l Marinelli, 55 % HPGe, 18 h) — with a different volume, detector and counting time it differs; below it, concentration is required (1); the laboratories’ ranges start at 0,1 Bq/l. With concentration: evaporation may remove volatile radionuclides, e.g. iodine and radon (1). With the upper limit: a dead time above 10 % requires the correctness of the correction to be shown (1). With the sample: only homogeneous samples or samples homogeneous after filtration (1); storage according to ISO 5667-3 (foreword). With the result: uncertainty, decision threshold and detection limit are calculated according to ISO 11929, and the 2021 edition added the shortest coverage interval (foreword); the WHO guidance level for 137Cs in drinking water is 10 Bq/l (introduction). With the unit: the standard gives the activity concentration in Bq/l (4); the laboratories also give Bq/kg.

WHAT WE DO NOT GIVE. We do not quote the requirements for standards, apparatus, calibration, sample preparation, formulae, corrections and the test report (Clauses 6–13, Annexes A–C) — they lie outside the samples. We have not read ISO 20042 and ISO 11929. We do not give parametric values from Polish drinking water regulations.

Method principle

Gamma radiation absorbed in a semiconductor detector (e.g. high-purity germanium) produces electron–hole pairs, recorded as pulses with an amplitude proportional to the energy; the energy spectrum allows full-energy peaks to be assigned to radionuclides. The activity concentration is calculated from the net peak area, the detection efficiency for the given geometry, the emission probability and the sample volume, with corrections for decay, dead time, pile-up and coincidence summing, in Bq/l with uncertainty, decision threshold and detection limit.

Applications

• Gamma emitters of 40 keV–2 MeV in drinking water, rainwater, surface water, groundwater, cooling water, industrial water and wastewater (1)
• Monitoring in planned, existing and emergency situations; effluents before discharge (introduction, 1)
• Water and water for human consumption — 137Cs in the accreditation scopes of 3 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN ISO 10703:2021-12

Title (PL)

Jakość wody — Radionuklidy emitujące promieniowanie gamma — Metoda badania z zastosowaniem wysokorozdzielczej spektrometrii promieniowania gamma

Title (EN)

Water quality — Gamma-ray emitting radionuclides — Test method using high resolution gamma-ray spectrometry

Step-by-step procedure

1. Sampling and storage

   According to the ISO 5667 series, storage according to ISO 5667-3 (2, foreword). PN-EN ISO 10703:2021-12 without a withdrawal note in PKN (03.10.2026).

2. Preparation

   Direct measurement or concentration by evaporation (with or without retention of iodine); filtration, homogeneity (1; details in 11.1, outside the sample).

3. Calibration

   Energy and efficiency — with sources or numerical methods (titles of 6, 11.2).

4. Measurement

   Spectrum of the sample, background and blank; dead time up to 10 % (1, 3.1, 3.2).

5. Result

   Activity concentration in Bq/l with corrections, uncertainty, decision threshold and detection limit (titles of 12).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Samples of elevated activity and standard sources — radiation protection rules
• Evaporation of samples — possible loss of volatile radionuclides (1)

Frequently asked questions