IAEA Coordinated Research Project Research Articles

The IAEA remote audit of small field dosimetry for testing the implementation of the TRS-483 code of practice.

The TRS‑483, an IAEA/AAPM International Code of Practice on dosimetry of small static photon fields, underwent testing via an IAEA coordinated research project (CRP). Alongside small field output factors (OFs) measurements using active dosimeters by CRP participants, the IAEA Dosimetry Laboratory received a mandate to formulate a remote small field dosimetry audit method using its passive dosimetry systems. This work aimed to develop a small field dosimetry audit methodology employing radiophotoluminescent dosimeters (RPLDs) and radiochromic films. The methodology was subsequently evaluated through a multicenter pilot study with CRP participants. The developments included designing and manufacturing a dosimeter holder set and the characterization of an RPLD system for measurements in small photon fields using the new holder. The audit included verification of small field OFs and lateral beam profiles for small fields. At first, treatment planning system (TPS) calculated OFs were checked against a reference data set that was available for conventional linacs. Second, calculated OFs were verified through the RPLD measurement of point doses in a machine-specific reference field, 4cm × 4cm, 2cm × 2cm, and 1cm × 1cm, corresponding size circularfields or nearest achievable field sizes. Lastly, profile checks in in-plane and cross-plane directions were done for the two smallest fields by comparing film measurements with TPS calculations at 20%, 50%, and 80% isodose levels. RPLD correction factors for small field measurements were approximately unity. However, they influenced the dose determination's overall uncertainty in small fields, estimated at 2.30% (k=1 level). Considering the previous experience in auditing reference beam output following the TRS-398 Code of Practice, the acceptance limit of 5% for the ratio of the dose determined by RPLD to the dose calculated by TPS, DRPLD/DTPS, was considered adequate. The multicenter pilot study included 15 participants from 14 countries (39 beams). Consistent with the previous findings, the results of the OF check against the reference data confirmed that TPSs tend to overestimate OFs for the smallest fields included in this exercise. All except three RPLD measurement results were within the acceptance limit, and the spread of results increased for smaller field sizes. The differences between the film measured and TPS calculated dose profiles were within 3mm for most of the beams checked; deviated results revealed problems with TPS commissioning and calibration of the treatment unit collimation systems. The newly developed small field dosimetry audit methodology proved effective and successfully complemented the CRP OF measurements by participants with RPLD audit results.

Analysis of loss of flow without scram test in the FFTF reactor – Part I: Preparation of neutronics data

This study presents a benchmark analysis of an unprotected loss of flow transient in a sodium-cooled fast reactor at the Fast Flux Test Facility (FFTF), carried out as part of an IAEA coordinated research project. Three codes, namely Serpent (Monte Carlo), DYN3D (3D nodal diffusion) and ATHLET (system thermal hydraulics), were employed in the benchmark exercise. Two distinct modeling approaches were utilized: 1) stand-alone ATHLET with point kinetics (PK) and system thermal hydraulics (TH); and 2) coupled DYN3D/ATHLET with spatial kinetics (SK) and system TH. Neutronics data essential for both approaches were generated using Serpent. The study is organized into three parts.Part I presents a summary of the preparation of neutronics data for PK or coupled SK/TH simulations and includes the outcomes of the static neutronics stage of the benchmark. The main focus lies on verifying the cross-section generation method for DYN3D by comparing its results against the reference Monte Carlo solutions obtained with Serpent.Part II will provide a detailed description of the ATHLET TH model of the system. This model will be thoroughly evaluated by comparing the results with the ANL benchmark solution and experimental data for the transient. Furthermore, a sensitivity analysis will be conducted to explore various modeling options and assess their impact on the simulation results.Part III will showcase the transient calculation results using the two modeling approaches. Additionally, an adaptive decay heat model for nodal codes will be introduced. The performance of both modeling approaches will be assessed by comparing their results to the available experimental data.

Photofission and photoneutron cross sections for 238U and 232Th

A specific objective of the recent IAEA Coordinated Research Project on Photonuclear Data and Photon Strength Functions (Code F41032; Duration 2016-2019) has been to measure photonuclear cross-section data where needed, for unexplored nuclei and cases of discrepant existing data. A dedicated experimental campaign has been conducted at the laser Compton-scattering γ-ray source of the NewSUBARU synchrotron radiation facility of SPring8, Japan, where photoneutron reactions for 11 nuclei from 9Be to 209Bi have been investigated in the Giant Dipole Resonance energy region. The measurements followed the development of a flat-effi ciency moderated neutron detection array and the associated neutron-multiplicity sorting techniques. The IAEA CRP campaign has been followed at NewSUBARU by new measurements of photofission and photoneutron reactions on 238U and 232Th in the energy range of 5.87 MeV – 20.14 MeV. The neutron-multiplicity sorting of high-multiplicity fission neutron coincidence events has been performed using a dedicated energy dependent, multiple firing statistical treatment. The photoneutron (γ, xn) and photofission (γ, fxn) reactions have been discriminated by considering a Gaussian distribution of prompt-fission-neutrons (PFN) multiplicities predicted by the evaporation theory. We here provide preliminary experimental (γ, n), (γ, 2n) and (γ, F) cross sections, average energies of PFN and of photoneutrons emitted in (γ, n) and (γ, 2n) reactions, as well as the mean number of PFN per fission act. The new 238U cross sections are compared with recent statistical-model calculations performed with the EMPIRE code on existing data.

Neutronics simulation of China Experimental Fast Reactor start-up tests using FARCOB and ERANOS 2.1 code systems

The neutronics analysis of selected start-up tests conducted from 2010 to 2011 in China Experimental Fast Reactor (CEFR) is carried out using in-house FARCOB and European ERANOS-2.1 code systems as a part of IAEA coordinated research project (CRP) on “Neutronics Benchmark of CEFR Start-Up Tests”. This exercise has the main objective of validation and verification of physical models, neutronics simulation methodology including cross-section libraries that is used for fast reactor core simulations. It is challenging to simulate such a small compact core of enriched uranium with high neutron leakage having stainless steel radial reflector by using 3-D diffusion theory codes. This benchmark analysis used a new simplified approach such as a 3-step method and experimental method for simulating temperature and sodium void reactivity coefficients. Net criticality, control rod worth, temperature and sodium void reactivity coefficients and swap reactivity could be predicted well within their measured error values. This exercise provided an additional validation of the FARCOB system against small sodium-cooled fast reactor (SFR) cores, and it can be confidently used for the design and analysis of small experimental reactor cores.

Prevalence and factors associated with sarcopenia in a cohort of patients with chronic pancreatitis

The neutronics analysis of selected start-up tests conducted from 2010 to 2011 in China Experimental Fast Reactor (CEFR) is carried out using in-house FARCOB and European ERANOS-2.1 code systems as a part of IAEA coordinated research project (CRP) on “Neutronics Benchmark of CEFR Start-Up Tests”. This exercise has the main objective of validation and verification of physical models, neutronics simulation methodology including cross-section libraries that is used for fast reactor core simulations. It is challenging to simulate such a small compact core of enriched uranium with high neutron leakage having stainless steel radial reflector by using 3-D diffusion theory codes. This benchmark analysis used a new simplified approach such as a 3-step method and experimental method for simulating temperature and sodium void reactivity coefficients. Net criticality, control rod worth, temperature and sodium void reactivity coefficients and swap reactivity could be predicted well within their measured error values. This exercise provided an additional validation of the FARCOB system against small sodium-cooled fast reactor (SFR) cores, and it can be confidently used for the design and analysis of small experimental reactor cores.

Verification of OpenMC for fast reactor physics analysis with China experimental fast reactor start-up tests

High-fidelity nuclear data libraries and neutronics simulation tools are essential for the development of fast reactors. The IAEA coordinated research project on “Neutronics Benchmark of CEFR Start-Up Tests” offers valuable data for the qualification of nuclear data libraries and neutronics codes. This paper focuses on the verification and validation of the CEFR start-up modelling using OpenMC Monte-Carlo code against the experimental measurements. The OpenMC simulation results agree well with the measurements in criticality, control rod worth, sodium void reactivity, temperature reactivity, subassembly swap reactivity, and reaction distribution. In feedback coefficient evaluations, an additional state method shows high consistency with lower uncertainty. Among 122 relative errors in the benchmark of the distribution of nuclear reaction, 104 errors are less than 10% and 84 errors are less than 5%. The results demonstrate the high reliability of OpenMC for its application in fast reactor simulations. In the companion paper, the influence of cross-section libraries is investigated using neutronics modelling in this paper.

Approaches to the definition of potentially exposed groups and potentially exposed populations of biota in the context of solid radioactive waste

A methodology for addressing the biosphere in safety assessments for solid radioactive waste disposal was developed through theme 1 of the IAEA coordinated research project on BIOsphere Modelling and ASSessment (BIOMASS) that ran from 1996 to 2001. This methodology provided guidance on how the biosphere can be addressed in safety assessments for disposal of solid radioactive waste. Since the methodology was developed, it has proven useful and has been widely referenced in assessments in a diversity of contexts encompassing both near-surface and deep geological disposal of solid radioactive waste. The principles that could be adopted for defining potentially exposed groups (PEGs) were an important aspect in the original BIOMASS methodology as the endpoint of an assessment usually includes the evaluation of individual dose or risk to human health. Identification of PEGs and definition of their characteristics are usually made to be consistent with the biosphere system description being developed, acknowledging that due to inherent uncertainties in projecting future human behaviour, the biosphere models adopted for assessing safety of a disposal system can only be illustrative. Since the publication of the original BIOMASS methodology, consideration has been extended to include potentially exposed populations of biota (PEPs), in the context of dose assessment and protection of the environment. Considering the need for the development of transfer pathways from a source term to an end point (for either PEGs or PEPs), the exposure modes that may occur and those to be assessed quantitatively should be identified. Within an expert working group (WG6) of the second phase of the IAEA coordinated project Modelling and Data for Radiological Impact Assessments (MODARIA II), the experience of participating organisations has been collected on topics associated with the definition of PEGs and PEPs using a questionnaire. The objective of the questionnaire was to review the current status and on-going discussions on the handling of issues related to definitions of PEGs and PEPs as an input to the development of biosphere models for assessing radiological impacts on human health and the environment. The answers received to the questionnaire provided a clear overview of the progress that has been made since the original BIOMASS methodology was published, together with the lessons learned from the application of that methodology in the development of safety cases. This paper summarises the questionnaire responses in five subject areas: (1) environment of the PEGs and its evolution; (2) linking the choice of PEGs to these environments; (3) food habits and consumption rates; (4) populations of non-human biota (PEPs) and (5) national and international regulations and guidance. We illustrate how the results of the questionnaire have been used to enhance the original BIOMASS methodology (IAEA Enhanced BIOMASS Methodology Report in press).

Assessment of measurement accuracy in 210Pb dating sediment methods

Working on an experimental dataset to derive descriptive parameters with well-known procedures appears to be a straightforward process. However, due to the complexity of environmental systems, the procedures cannot be completely defined, and commonly hypothesis are required to obtain final results. These degrees of freedom cause a spread in results that is often wider than the experimental uncertainties and that should be taken into account in the measurement accuracy estimation. As an example of this issue, the sources of uncertainty, including reproducibility, that occur in dating marine and lacustrine sediment cores with the 210Pb methodology are discussed in this paper. The IAEA Coordinated Research Project (CRP) “Study of Temporal Trends of Pollution in Selected Coastal Areas by the application of Isotopic and Nuclear Tools” promoted this discussion, its main objective being the determination of a streamlined, harmonised and validated methodology for marine sediment dating. The uncertainties estimated from experimental data and mathematical propagated must be complemented with reproducibility contribution: some elements are specific for the 210Pb method (mixed layer, finite thickness of layers and identification of the equilibrium depth), while others are more general (exponential fitting and data interpolation). The final spreading of results can be mainly controlled by reproducibility, and efforts are needed to standardise procedures to reduce the effect of reproducibility and to better estimate the overall uncertainty of measurements. It is necessary to underline the importance of a thorough (a-priori) cost-effective analysis of the uncertainty evaluation of the measurement results in relation to the aim of the study, taking primarily into account the overall accuracy required case by case.

Microscopic study of higher-order deformation effects on the ground states of superheavy nuclei around 270Hs * *Supporteds by the National Key R&D Program of China (2018YFA0404402), the National Natural Science Foundation of China (11525524, 12070131001, 12047503, 11975237, 11961141004), the Key Research Program of Frontier Sciences of Chinese Academy of Sciences (QYZDB-SSWSYS013), the Strategic Priority Research Program of Chinese Academy of

We investigate the effects of higher-order deformations ( and 10) on the ground state properties of superheavy nuclei (SHN) near the doubly magic deformed nucleus using the multidimensionally-constrained relativistic mean-field (MDC-RMF) model with five effective interactions: PC-PK1, PK1, NL3*, DD-ME2, and PKDD. The doubly magic properties of include large energy gaps at and in the single-particle spectra. By investigating the binding energies and single-particle levels of in the multidimensional deformation space, we find that, among these higher-order deformations, the deformation has the greatest impact on the binding energy and influences the shell gaps considerably. Similar conclusions hold for other SHN near . Our calculations demonstrate that the deformation must be considered when studying SHN using MDC-RMF.

PERFORMANCE OF HANDHELD NAI(TL) SPECTROMETERS AS DOSIMETERS BY LABORATORY AND FIELD DOSE RATE MEASUREMENTS.

In the framework of the IAEA Coordinated Research Project (CRP) J02012 on 'Advancing Radiation Detection Equipment for Detecting Nuclear and Other Radioactive Material Out of Regulatory Control', the properties of two commercial instruments (1) InSpector 1000 analyzer (Canberra), with a 2″×2″ NaI(Tl) scintillator and (2) RIIDEYE M-G3 analyzer (Thermo Scientific), with a 3″×3″ NaI(Tl) scintillator, were evaluated as dosimeters by laboratory and field measurements. In the Ionizing Radiation Calibration Laboratory (IRCL) of the Greek Atomic Energy Commission, the NaI(Tl) spectrometers were tested in order to measure Ambient gamma Dose Equivalent Rate (ADER). The NaI(Tl) scintillators were irradiated in a homogeneous field with 662 keV photons with different ADER values from 0.17 to 100μSv h-1 at 0° incidence (irradiation field perpendicular to the detector's front window) and at 90° incidence. For each irradiation, the measured ADER by the spectrometers and the 'true' ADER values (provided by the IRCL) were compared. In addition, the angular dependence (0-359°) of the ADER response of the spectrometers was studied with a 152Eu source placed at 1, 2 and 3m from the spectrometers. The ADER dependence as function of the distance from the 152Eu source (at 0° incidence) measured by the two detectors was compared with the theoretical one. In the field studies, ADER was measured by the spectrometers at seven locations belonging to the Greek Early Warning System Network (which is based on Reuter-Stokes ionization chambers). These locations have different ADER values ranging from 20 to 120 nSv h-1. In these locations, gamma ADER were also deduced (1) by in situ gamma spectrometry measurements with portable Germanium HPGe detectors and (2) by the Reuter-Stokes ionization chambers (by subtraction of the cosmic radiation). Gamma dose measurements were also performed with the InSpector 1000 and RIIDEYE M-G3 detectors in 25 locations (beaches) of Northern Greece and compared with the ADER values deduced by sand sample analysis with gamma spectroscopy. Beaches with sand are good candidates for such type of measurements since they are commonly flat and in principle the natural radionuclides are homogenously distributed.

Generation of clinical 177Lu SPECT/CT images based on Monte Carlo simulation with GATE.

Patient-specific dosimetry in MRT relies on quantitative imaging, pharmacokinetic assessment and absorbed dose calculation. The DosiTest project was initiated to evaluate the uncertainties associated with each step of the clinical dosimetry workflow through a virtual multicentric clinical trial. This work presents the generation of simulated clinical SPECT datasets based on GATE Monte Carlo modelling with its corresponding experimental CT image, which can subsequently be processed by commercial image workstations. This study considers a therapy cycle of 6.85GBq 177Lu-labelled DOTATATE derived from an IAEA-Coordinated Research Project (E23005) on "Dosimetry in Radiopharmaceutical therapy for personalised patient treatment". Patient images were acquired on a GE Infinia-Hawkeye 4 gamma camera using a medium energy (ME) collimator. Simulated SPECT projections were generated based on experimental time points and validated against experimental SPECT projections using flattened profiles and gamma index. The simulated projections were then incorporated into the patient SPECT/CT DICOM envelopes for processing and their reconstruction within a commercial image workstation. Gamma index passing rate (2% - 1 pixel criteria) between 95 and 98% and average gamma between 0.28 and 0.35 among different time points revealed high similarity between simulated and experimental images. Image reconstruction of the simulated projections was successful on HERMES and Xeleris workstations, a major step forward for the initiation of a multicentric virtual clinical dosimetry trial based on simulated SPECT/CT images. Realistic 177Lu patient SPECT projections were generated in GATE. These modelled datasets will be circulated to different clinical departments to perform dosimetry in order to assess the uncertainties in the entire dosimetric chain.

Developing and implementing a multi-modality imaging optimization study in paediatric radiology: Experience and recommendations from an IAEA coordinated research project.

Optimization of imaging examinations is a key requirement of both the International and European Basic Safety Standards, and the focus of much international activity. Although methodologies are well established in principle, there continues to be a variety of practical issues both in collecting and interpreting dose and image quality data and in making successful interventions to optimize exposures. A Coordinated Research Project, involving institutes from ten different countries, was established by the IAEA to assess the efficacy of recommended optimization methodologies in the field of paediatric radiology and to derive practical guidance on their implementation. The steps followed in this process were identification of the imaging process to be investigated (abdomen and chest x-rays, micturating cysto-urethrograms, and brain & thorax CT scans); collection of dose and image quality data; evaluation and comparison of the data between institutes and to standards; identification and implementation of interventions for optimization; and re-evaluation of dose and image quality parameters. The project succeeded both in achieving effective interventions for optimization of specific imaging tasks in individual institutes and in identifying key issues with potential to handicap this process. The main area in which problems were encountered was in the collation of reliable dose and image quality data. The reasons for this were explored and a series of recommendations have been made, summarized into 'ten practical tips' for optimization to assist institutes, particularly those in the early stages of addressing optimization issues.

COUPLED MODELLING OF THE EBR-II SHRT-45R INCLUDING PHOTON HEAT DEPOSITION

The Fast REactor NEutronics/Thermal-hydraulICs (FRENETIC) code has been developed during the last years at Politecnico di Torino, implementing a full-core coupled neutronic/thermal-hydraulics model for steady-state and transient analysis of liquid-metal cooled fast breeder reactor (LMFBR). In the framework of the validation activities for the code, an analysis of the sodium-cooled reactor EBR-II, previously carried out in the frame of a IAEA Coordinated Research Project, is performed with FRENETIC including the most recent physics models. In particular, photon transport and heat deposition are taken into account, a feature which has been proved in previous studies to be relevant to the correct study of the EBR-II core. To this purpose, a set of nuclear data for photons has been generated by means of the Monte Carlo code Serpent-2, and it is demonstrated that the code is able to take into account the photon heat deposition in the EBR-II.

Accounting for Uranium-234 During the Analysis of Experiments at the Research Fast Reactor with High Enrichment

Paper is an attempt to consider the influence of U-234 presence through the comparison of the calculated assessments of the temperature reactivity effect (TRE) and the sodium void reactivity effect (SVRE) of the fast research reactor CEFR with 64.4% enrichment on U-235 isotope and measured values of the temperature reactivity effect and sodium void reactivity effect. Additional investigation was performed to account for U-234 in the first criticality experiment. Experimental data are provided in frames of IAEA Coordinated Research Project “Neutronics Benchmark of CEFR Start-Up Tests”. The content of U-234 was calculated by us using mathematical model of the quasi-ideal enrichment cascade. Due to the high enrichment, the content of U-234, although still small, has ceased to be vanishingly small. The effect caused by this isotope is appeared not only through the presence of new isotope in the fuel load, but also in a decrease in the mass of the U-238 isotope in the fuel load. It is shown, that accounting for U-234 slightly increases the agreement of the calculated assessments of TRE among themselves (values of deviation shifted toward each other)/Also accounting for the U-234 isotope leads to a small but systematic increase in the values of the effective multiplication factor by 120-150 pcm.

IAEA Activities on 67Cu, 186Re, 47Sc Theranostic Radionuclides and Radiopharmaceuticals.

Despite interesting properties, the use of 67Cu, 186Re and 47Sc theranostic radionuclides in preclinical studies and clinical trials is curtailed by their limited availability due to a lack of widely established production methods. An IAEA Coordinated Research Project (CRP) was initiated to identify important technical issues related to the production and quality control of these emerging radionuclides and related radiopharmaceuticals, based on the request from IAEA Member States. The international team worked on targetry, separation, quality control and radiopharmaceutical aspects of the radionuclides obtained from research reactors and cyclotrons leading to preparation of a standard recommendations for all Member States. The CRP was initiated in 2016 with fourteen participants from thirteen Member States from four continents. Extraordinary results on the production, quality control and preclinical evaluation of selected radionuclides were reported in this project that was finalized in 2020. The outcomes, outputs and results of this project achieved by participating Member States are described in this minireview.

Analysis of fuel rod behavior during loss-of-coolant accidents using the BISON code: Cladding modeling developments and simulation of separate-effects experiments

BISON is a finite-element based, multidimensional fuel performance code developed at Idaho National Laboratory. In this paper, we present BISON modeling developments for Zircaloy nuclear fuel cladding behavior under loss-of-coolant accident (LOCA) conditions and code validation to separate-effects experiments. Code developments include models for cladding high-temperature creep, crystallographic phase transition, high-temperature steam oxidation and failure due to burst. Code validation is performed against a substantial number of experimental tests for ballooning and burst behavior of Zircaloy claddings under LOCA conditions. Validation calculations are completed using 2D axisymmetric models. Additionally, we present a 3D calculation that demonstrates simulation of the cladding response in presence of azimuthal temperature variations. Calculated results are systematically compared to experimental data of cladding temperature, inner pressure and time at burst failure. Several of the presented BISON validation cases were developed in the framework of the IAEA Coordinated Research Project FUMAC. BISON modeling developments for UO2 fuel behavior under LOCA conditions and code validation to integral fuel rod experiments are presented in a complementary paper.

Developing and Implementing an Imaging Optimization Study in Pediatric Nuclear Medicine: Experience and Recommendations from an IAEA-Coordinated Research Project.

The International Atomic Energy Agency instituted a coordinated research project on the evaluation and optimization of pediatric imaging, addressing the lack of consistency in this field. The purpose was to develop and test an optimization schema for the practices of pediatric radiology and nuclear medicine. Methods: A 5-step optimization schema was developed. Once a protocol optimization is identified, the steps are as follows: identification of the imaging situation; collection of administered-activity data and evaluation of the diagnostic image quality at baseline; comparison of baseline administered activity data with published standards or other benchmarks; identification of intervention, if necessary; and implementation of intervention and evaluation. Results: Within the coordinated research project, two sites considered optimization projects regarding nuclear medicine. In this work, renal imaging using 99mTc-dimercaptosuccinic acid (DMSA) projects are presented as examples. Site 1 acquired its standard 300-s static 99mTc-DMSA studies as 5-frame dynamic studies in 29 children. Frames were added to simulate different levels of administered activity. Image quality was subjectively judged on a 3-point Likert scale. A 30% reduction in administered activity with increased imaging duration (350 s) across all age groups was shown to be acceptable. This reduction was implemented and evaluated in 31 subsequent children, yielding administered activities significantly lower than baseline (mean relative differences of 30%, 37%, and 38% for children aged 0-5, 5-10, and 10-15 y, respectively). Site 2 performed a phantom study to determine the impact of lowering administered activity on image noise, finding that administered activities could be significantly lowered if longer imaging times were used. This led to a 50%-70% reduction from baseline with no loss in image quality. Conclusion: A dose optimization approach was applied successfully for several procedures commonly performed in pediatric nuclear medicine. Results are reported for renal cortical imaging using 99mTc-DMSA, leading to significant reductions in administered activity (and thus radiation dose). This optimization schema can be successfully implemented by nuclear medicine clinics seeking to improve their approach to imaging children.

226Th nuclear decay data evaluation

Following the recent evaluation of the nuclear decay data of 230U, a similar evaluation for its daughter, 226Th, a radionuclide of interest for targeted alpha therapy, was undertaken within the Decay Data Evaluation Project (DDEP) and an IAEA Coordinated Research Project. The nuclear decay data presented are: the half-life, decay energy, alpha-particle emission energies and probabilities, internal conversion coefficients and gamma-ray energies and emission intensities. These new data will be included in the DDEP database NUCLEIDE.

Recommended nuclear data for medical radioisotope production: diagnostic positron emitters

An IAEA coordinated research project that began in 2012 and ended in 2016 was primarily dedicated to the compilation, evaluation and recommendation of cross-section data for the production of medical radionuclides. One significant part of this work focused on diagnostic positron emitters. These particular studies consist of 69 reactions for direct and indirect or generator production of 44Sc(44Ti), 52mMn(52Fe), 52gMn, 55Co, 61Cu, 62Cu(62Zn), 66Ga, 68Ga(68Ge), 72As(72Se), 73Se, 76Br, 82Rb(82Sr), 82mRb, 86Y, 89Zr, 90Nb, 94mTc, 110mIn(110Sn), 118Sb(118Te), 120I, 122I(122Xe), 128Cs(128Ba), and 140Pr(140Nd) medical radionuclides. The resulting reference cross-section data were obtained from Padé fits to selected and corrected experimental data, and integral thick target yields were subsequently deduced. Uncertainties in the fitted results were estimated via a Padé least-squares method with the addition of a 4% assessed systematic uncertainty. Experimental data were also compared with theoretical predictions available from the TENDL-2015 and TENDL-2017 libraries. All of the numerical reference cross-section data with their corresponding uncertainties and deduced integral thick target yields are available on-line at the IAEA-NDS medical portal www-nds.iaea.org/medicalportal and also at the IAEA-NDS web page www-nds.iaea.org/medical/positron_emitters.html.

Activities of an IAEA Coordinated Research Project on Advanced Cold Moderators

In 2014, a Coordinated Research Project (CRP) directed toward studying “Advanced Moderators for Intense Cold Neutron Beams in Materials Research” was initiated under the auspices of the IAEA. The C...