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Sample Preparation for ( n, g ) Cross Section Measurements of Actinides. M. Rossbach , Institute for Energy and Climate Research, Nuclear Waste Disposal and Reactor Safety , IEK-6, Forschungszentrum Juelich GmbH, 52425 Juelich , Germany. Mitglied der Helmholtz-Gemeinschaft. Content:.

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  1. Sample Preparationfor (n,g) Cross SectionMeasurementsofActinides M. Rossbach, Institute forEnergyandClimate Research, NuclearWasteDisposalandReactorSafety, IEK-6, Forschungszentrum Juelich GmbH, 52425 Juelich, Germany Mitglied der Helmholtz-Gemeinschaft

  2. Content: Motivation – Nuclear Data ofActinides Sample preparation Irradiation andspectrumevaluation

  3. Motivation Comparison of thermal capture cross sections for 243Am(n,g)244Am with existing and evaluated data

  4. Comparison of thermal capture cross sections for 231Pa(n,g) 232Pa with existing and evaluated data Motivation

  5. Vergleich von Wirkungsquerschnitten einiger relevanter Actinide in unterschiedlichen evaluierten Datenkatalogen, ENDF (Brookhaven, USA), JENDL-4.0 (Japan) und JEFF3.3 ( OECD-NEA) Motivation

  6. Motivation Actinidecontentofreprocessednuclearwastefrom La HagueorSellafieldisestimatedthroughdelayedneutroncountingand an estimatednuclidevector. Nodirectmeasurementsareavailable. Development of a PGAA basedanalyticalmethodcouldhelptoevaluateactinidecontent in complexsamples, such asnuclearwasteorSafeguardswipesamples. Accuratecrosssectiondataareneededtoapply PGAA as an analyticalmethodforactinidequantification. Low uncertaintyofthesedata will helptoimprovereliabilityofresults. Atthe Budapest Research Reactor a versatile PGAA instrumentand high levelofexpertiseisavalableforexperiments (thermal equivalentcoldneutronflux = 2.3x107 cm-2 s-1). Atthe Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM-II) in Garching thehighestneutronfluxof 7x109 cm-2 s-1isavailablefor sample irradiations.

  7. Sample preparationforcoldneutronirradiation First atemptofsmallpallets in aluminiumfailedbecausethepalletscouldmovearound in thesandwich.

  8. Sample preparationforcoldneutronirradiation Encapsulation in smallSuprasilquartzampoules was not conclusivebecauseofbadlydefinedgeometryandsegregationof Au powder.

  9. Sample preparationforcoldneutronirradiation Neutron radiographic image of the 242PuO2 samples in quartz ampules. The first two contain gold powder as a flux monitor.

  10. Sample preparationforcoldneutronirradiation Thereforewedecidedto press 3mm diam. palletsandplacethem in a sandwichof 3 quartzglassplates, themiddleonewith a 3 mm diam. hole in itscenter:

  11. Sample preparationforcoldneutronirradiation …or a tinydropofactivity on a 3mm diam. Au foilcentered on a quartzplateforfluxmonitoring. Anotherquartzplatetocovertheactivityisglued on top withepoxy.

  12. Budapest irradiation facility, 2 x 107 n cm-2 s-1, Compton suppressed FRM II irradiation facility, 7 x 109 n cm-2 s-1 Compton suppressed Irradiations

  13. Results 242Pu prompt Gamma Spektrum 237Np prompt Gamma Spektrum • Prompt 27Al • Prompt 28Si • Prompt 29Si • Prompt 30Si • Prompt 14N • Prompt 237Np • Decay238Np • Decay237Np • Decay233Pa • Prompt 27Al • Prompt 28Si • Prompt 29Si • Prompt 30Si • Prompt 14N • Prompt 242Pu • Decay243Pu • Decay243Am • Decay241Am Spectrumconsistsofabout 600 peaks in theenergyrangefrom 40 keVto 12 MeV Spectrumconsistsofabout 600 peaks in theenergyrangefrom 40 keVto 12 MeV

  14. P F = 411 thermal equivalent neutron flux in the sample is: , n × s × N t Au 411 irr Evaluation ofspectra partial gamma ray production cross section is Monte Carlo simulations using the Geant4 code were carried out to account for self-shielding effects in the sample. P is the corrected peak area, σthe corresponding partial gamma ray production cross section , N the number of atoms and tirr the irradiation time. gamma ray spectra were evaluated using Hypermet-PC

  15. Future plans: PGAA usingfissionneutrons At FRM II a positiontousefissionneutronsforirradiationexists(1-2 MeV, 4.9 E+6 cm-2s-1, crosssection: 30 x 30 cm) A uraniumtargetclosetothebiologicalshield ofthereactorgenerates a beam of fast neutrons extractedto a bunker. Weexpecttoinvestigateotherreactionchannels such as (n,n‘), (n,2n), (n,a) or (n,p). Considering a neutrongeneratorbasedanalytical methodthiswouldconstitute an importantstep forward.

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