This report describes the preparation and certification of the 242Pu spike reference material IRMM-049e, applied for determination of plutonium content in nuclear materials by isotope dilution mass spectrometry (IDMS) in nuclear safeguards, nuclear security and in the industry. As the stock of IRMM-049d is close to exhaustion, it was decided to produce about 90 ampoules of a new spike certified reference material (CRM) IRMM-049e and, therefore to maintain the provision of the IRMM-049 series of spike CRMs.
IRMM-049e is the first of the IRMM-049 series produced in compliance with ISO 17034:2016.
The amount content of 242Pu in IRMM-049e was characterised on 10 randomly stratified selected units by Isotope Dilution – Thermal Ionisation Mass Spectrometry (ID-TIMS) using the IRMM-1027o CRM as a spike. The plutonium isotope amount ratios were measured using the same 10 selected units by TIMS. The material was finally certified for the amount content of 242Pu and the total Pu, the mass fractions of 242Pu and total Pu, the Pu isotope amount ratios as well as the plutonium isotope abundances as amount and mass fractions, and for the molar mass of Pu in IRMM-049e.
The certified values were confirmed by ID-TIMS using the IRMM-086 (239Pu spike) and verified against the reference value of the external certified test sample Pu EQRAIN-13 provided by CEA/CETAMA.
These verification studies were carried out in the frame of the on-going inter-calibration campaign using state-of-the art measurement procedures linking together different JRC plutonium spike reference materials and also external reference materials to underpin the confidence in the use of JRC isotopic plutonium reference materials for safeguards verification.
Between unit-homogeneity was quantified in accordance with ISO Guide 35:2006. No stability study was performed for this reference material since the general behaviour of this material is well known from past experience. However, a post-certification stability monitoring will be done every two years to control its stability after issuance of the certificate.
The uncertainties of the certified values were estimated in compliance with the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainties related to characterisation and possible inhomogeneity.
The main purpose of this material is for use as a spike isotopic reference material for quantification of plutonium in an unknown nuclear sample. IRMM-049e is supplied in a screw-cap glass ampoule containing 10 mL nitric acid solution (c = 5 mol/L) with a certified plutonium (total Pu) mass fraction of (91.52 ± 0.12) µg/g and a certified 242Pu amount content of (0.35828 ± 0.00045) µmol/g.
Because the IRMM-049e material is a true solution and as such, can be regarded as completely homogeneous, there is no minimum sample intake to be taken into account for the analysis.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard
