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Metrology and quality assurance for nuclear safeguards

Objective

Specific Objectives

- To support European and other international organisations in setting up an internationally structured system for nuclear isotopic measurements;

- To supply the EU with the best possible nuclear isotopic reference measurements and materials as and when required.
Planned Deliverables

Specific Deliverables to DGs

- A series of Large Size Dried Spikes for analysis of amounts of uranium and plutonium in input tank solutions will be completed (1027f);

- One REIMEP campaign will be completed;

- One NUSIMEP campaign will be completed;

- A set of uranium-doped swipes for Quality Control (EURATOM/IAEA) will be produced.

Deliverables as a result of the research

- A set of uranium isotopic mixtures will be prepared with the aim of providing calibration for minor isotope measurements in uranium by mass-spectrometry;

- The first reference filaments for uranium isotopic measurements on TIMS will be prepared;

- Present results of measurements using new U spike at a major conference;

- Complete acceptance of filament oven (HITEC) and the basic work to understand the processes occurring on TIMS filaments.

Summary of deliverables made by: 31/12/2001

Preparation of IRMs by gravimetric mixing Safeguards authorities, Analytical NMC laboratories
The need to produce new IRMs requires the development of gravimetric mixing techniques.
Following the installation of 3 new glove-boxes, highly enriched 238U oxide was dissolved, purification was carried out but contamination problems were encountered and are presently being investigated.

Preparation of metal filament RMs Analytical NMC laboratories
The preparation of filaments for mass spectrometry is important for customers (IRM users).
Measurements of uranium electro-deposited on filaments were made in order to determine the reference status on the mass-spectrometer. Non-linear behaviour of the electron multipliers was investigated and first tests made on the oven at HITEC highlighted some required design changes.
Extensive measurements were made on electrodeposited sources and the dead-time was determined by electronic means. Measurement ratios were also performed using IRMM-072. These measurements will form a base line for measurements done with the oven-prepared filaments. The filament oven was transported to IRMM, installed and first tests were made. The acceptance report is presently being drafted.

Large spikes Analytical NMC laboratories
The accepted method to reduce uncertainties in the measurement of U and Pu in reprocessing input solutions is by the application of large size dried spikes. IRMM delivers these spikes around the world with a guaranteed low uncertainty and trace ability to the SI.
The verification of a mother solution for Pu/U content and isotopic abundances was finished. Vial filling started for the IRMM-1027f LSD spike and experiments were successfully carried out using CAB (on 168 units) as an alternative material. U and Pu content results on the latter were verified by IDMS. A verification campaign started using typical nuclear reprocessing plant conditions (specifically: JNC, Japan) to see how far the new spikes meet the field requirements.

Dilute RMs Safeguards authorities and Analytical NMC laboratories
The improvement in sensitivity in measurement devices (e.g. ICP-MS) has led to a demand for dilute IRMs.
IRMM-073 (dilution of IRMM-072 for environmental purposes) was prepared, ampoule and labelling and packing is presently ongoing. Calculations were made on the possible interferences (contamination) during the dilution process and results show that the certificate of the 072 series can be used without added uncertainty factors.
IRMM-058, a highly enriched 233U spike for measurement of U in environmental samples, was prepared, ampoule, labelled and packed. Certification measurements were carried out and the certificate and certification report is being prepared.

Uranium isotopes: Safeguards authorities, Analytical NMC laboratories
IRMM has the best uranium isotope mixing and measurement capabilities (for LEU) in the world and this expertise forms the basis for the production of IRMs and certified test samples (CTS).
The JNFL series was completed, the samples were prepared for transport and dispatched on schedule thereby completing this contract. The mass-spectrometer was rewired to improve safety in the laboratory. A series of samples from IPEN, Sao Paulo, Brazil (ABACC) were also measured for 235U enrichment and presently the minor isotopics for these materials are being measured.

External safeguards QC: REIMEP-15 Safeguards authorities, Analytical NMC laboratories
IRMM provides the only objective external Quality Control programme for nuclear Safeguards measurements (REIMEP) and also offers specific external Quality Control materials suitable for Safeguards laboratories.
7 results were received and in return all these participants received certificates. The first version of participant's report was prepared, approved and sent to all participants. In total, 9 sets of measurements were performed in this campaign. Thus REIMEP-15 was completed and planning for REIMEP-17 (uranium isotopics) and REIMEP 18 has already commenced.

NUSIMEP Safeguards authorities, Analytical NMC laboratories
IRMM has the unique ability to prepare very dilute Certified Test Samples of actinides, based on the preparation of isotopically mixed materials and ultra clean lab facilities. The INFCIRC/540 protocol of IAEA for the measurement of environmental samples for the U and Pu isotopic content means there is a world-wide need for these materials.
The final participants' report for NUSIMEP-2 was completed, sent out to the participants and the planning for subsequent rounds begun. Invitations for participation in NUSIMEP-3: 'uranium isotopic abundances in saline media' were sent out to potential participants and the investigations on sample preparation were carried out. Suitable samples were selected and blank measurements performed. The preparation of samples is presently ongoing.

Environmental RMs Safeguards authorities, especially DG TREN, Analytical NMC laboratories
There is a growing demand for low-level RMs and measurements thereof. IRMM can make such low-level RMs using the ultra clean lab facilities.
Measurements of the natural U content in blank cotton swipes were performed and values obtained of ca. 12ng/g were too high to allow these swipes to be used as the basis of isotopic reference Quality Control swipes as requested by ESO. UO2 particles were delivered from Harwell, UK for ESO with the request to measure and verify isotopic abundances. First 'bulk' certified external QC samples were made for uranium on paper filters and made ready to send to the European Safeguards Office (ESO) in Luxembourg. Blank measurements were made on the paper blanks and the first QC swipes were delivered to JRC-ITU.

Recertification of NBS 946, 947, 948 Pu IRMs Analytical NMC laboratories
As part of the need to have world-wide accepted, traceable isotopic reference materials, IRMM has started a re-certification of well-known IRMs of U and Pu. The effect of decay on these original NBS Pu IRMs means that their use today is limited by the certified uncertainty.
Measurements of NBS SRM-946, 947 and 948 were completed and the certification procedure is presently in progress. Provisional certificates were drafted and it is predicted to complete this task by the end of 2001.

Certification of isotopic abundances of MP2 Analytical NMC laboratories
The French MP2 Reference Material for Pu has never been certified for isotopic abundances so in cooperation with CETAMA, IRMM is performing the latter.
MP2 samples were measured and the certificate was prepared. A joint certificate between Cetama/CEA and IRMM is presently being developed.

Certification of MOX samples Safeguards authorities, Analytical NMC laboratories
This work was requested both by Luxembourg (DG TREND) as well as official requests from external customers.
Isotopic abundances were measured for Pu in dissolved MOX samples and the certification was completed. The uranium isotopics were measured as well as the molecular weight of U thereby completing this task.

Isotope Deliveries Safeguards authorities, DG TREN, external customers
Support for DCS, Luxembourg (DG ENER) and catalogue sales.
The following transports of IRMS took place in 2001: SCK, Belgium; Oak Ridge National Laboratory, USA; University of Cambridge, UK; Forschungszentrum Karlsruhe, Germany; JRC-ITU, Germany; Inst. for Physics & Power Engineering, Russia; SCK, Belgium; DTT Belgian Army, Belgium; NNC, UK; OSL, Sellafield, UK; LSS, La Hague, France; BNFL, UK.

ECSAM measurements DG TREN
IRMM is requested by ESO (DG TREN) to carry out a number of Safeguards measurements per year. These are normally samples, which are collected at JRC-ITU or from Belgian sites.
The dissolution of 2 MOX samples (one pellet and an oxide) was completed and the certification of Pu and U (isotope abundances and contents) was performed. Pu measurements were performed and the certificates for MOX and PU oxide ECSAM samples were produced. The results have been sent to ESO.

Output Indicators and Impact

Consolidate and expand leading position as largest world supplier of nuclear isotopic RMs and spikes. Production of new Isotopic Reference Materials and spikes of U and Pu for use in reprocessing plants (on-site Laboratories Sellafield and La Hague and Japan), development of a set of global IRMs of uranium (collaboration with NBL, USA). Prepare new Pu IRMs and spikes using the enriched Pu-244 material from Arzamas, Russia (in collaboration with the DOE and IAEA).
Summary of the project

IRMM specialises in Primary Methods of Measurement and Primary Reference Materials (elemental and isotopic). These provide the basis for trace ability - hence comparability - of nuclear measurements carried out by Nuclear Plant Operators and Safeguard Authorities (IAEA or EURATOM) as well as for materials exported from or imported into the European Community.
So with special focus on metrology and quality assurance for nuclear safeguards and in close collaboration with the EURATOM Safeguards Directorate and DG RELEX (IAEA), IRMM has the capacity and established impartiality to perform referee measurements needed for Nuclear Safeguards and to maintain and expand an independent European metrological capability in the area of nuclear analysis.
In this project, IRMM provides it's customers with CRMs and reference measurements for nuclear and environmental safeguards and thus provide a vital link in the chain of metrology and trace ability of measurements. Through programmes like REIMEP and NUSIMEP, customers can benchmark themselves for specific nuclear measurements. They may provide candidate reference materials, participate in international evaluation rounds, proficiency testing exercises, seek advice on aspects of nuclear isotopic measurements and/or nuclear isotopic reference materials, exchange information and help contribute the maintenance of a reliable measurement system for nuclear safeguards. On regular occasions, scientists from these organisations come to work at IRMM and use the unique facilities.

Rationale

IRMM has an independent European metrological capability in the area of nuclear analysis as well as being the largest world supplier of isotopic reference materials (IRMs) and spikes.
IRMM has one of the largest isotope mass-spectrometry infrastructure in Europe (10 high performance mass spectrometers (ThI/EI-MS, ICP-MS) currently used for measurements of nuclear materials with an adjoining ultra-clean chemical laboratory (class 5, 120 m², 16 work places with corrosion resistant construction) thus an excellent potential for the certification of IRMs and spikes. Due to its demonstrated measurement capability, IRMM was invited by the US Department of Energy to develop jointly with New Brunswick Laboratory, Argonne, the official US Safeguards Laboratory, the global reference material for the accountancy of uranium.

Funding Scheme

JRC - Joint Research Centre research

Coordinator

Institute for Reference Materials and Measurements
Address
Retieseweg
B-2440 Geel
Belgium