Foreword

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This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection, Subcommittee SC 2, Radiological protection.

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Introduction

In the course of employment, individuals might work with radioactive materials that, under certain circumstances, could be taken into the body. Minimising the risks to workers from incorporated radionuclides requires the monitoring of potential or actual intakes. This monitoring involves the measurement of the activity of the radionuclides in the body (in vivo measurement) and/or biological samples, e.g. urine or faeces (in vitro measurement).

Analytical methods for plutonium urine bioassay are addressed in this document because of:

the convenience of urine sampling and relatively easy sample processing. Urine bioassay is the most commonly used in vitro measurement method for accurately assessing the magnitude of internal contamination;
the high radiotoxicity of Pu isotopes (e.g. ²³⁸Pu, ²³⁹Pu and ²⁴⁰Pu) due to their long half-lives, highly energetic alpha emission and ability to accumulate into bone and organs;
the major contribution of Pu isotopes to the internal contamination in many situations, and the relatively low detection limits of Pu isotopes compared to the other highly radiotoxic actinides.

For routine individual monitoring, the detection of all exposures whose sum can lead to an annual dose exceeding 1 mSv should be ensured according to ISO 20553 . In emergency situations, the urine bioassay techniques should be sufficiently sensitive to meet the maximum value for reference level of 0,1 Sv recommended by the International Commission on Radiological Protection (ICRP)^[ 1 ^][ 2 ^][ 3 ^].

This document offers general requirements for sample processing and measurement of the activity concentration of Pu isotopes in urine samples. Examples of detailed procedures are given in the annexes for different monitoring situations.

1 Scope

This document specifies approaches for the determination of plutonium isotopes (²³⁸Pu, ²³⁹Pu and ²⁴⁰Pu) in urine using alpha spectrometry or inductively coupled plasma mass spectrometry (ICP-MS).

It is applicable to the measurement of plutonium isotopes at levels which are appropriate for

workers handling plutonium in planned exposure situations, where detection limits are sufficiently low to be in accordance with dose limits, and
workers, members of the public and emergency responders in emergency exposure situations, where required detection limits can be much higher, and results need to be reported in a short timescale.

This document does not provide information on when monitoring is carried out or the interpretation of the results in terms of dose or biological effects.

2 Normative references

3 Terms and definitions

4 Symbols

5 Principle

6 Chemical reagents and apparatus

6.1 Chemical reagents

6.2 Apparatus

7 Sample preparation procedure

7.1 General

7.2 Sample pre-concentration

7.3 Organics decomposition

7.4 Chemical separation

7.5 Sample preparation for measurement

8 Measurement

8.1 Alpha spectrometer measurement

8.2 ICP-MS measurement

9 Expression of results

10 Test report

11 Quality assurance and quality control program

11.1 General

11.2 Variables that can influence the measurement

11.3 Instrument verification

11.4 Contamination

11.5 Interference control

11.6 Method verification

11.7 Demonstration of analyst capability

Bibliography