Oct.18, Neutron Field and Induced Radioactivity in IFMIF Environment M. Sugimoto(JAERI) IEA International Work Shop on Fusion Neutronics The Kongreshous Baden-Baden, Germany

Oct.18, Contents 1.IFMIF Overview 2.Issues Related to Neutronics and Radiation Safety 3.Source Neutron Characteristics 4.Deuteron Induced Radioactivity 5.Requirements for Neutron Nuclear Data 6.Summary

Oct.18, Test specimen s Deuteron beam Li target D+ 7 Li → ｎ＋ ８ Be or ｎ＋ｐ＋ 7 Li etc. Ｄ - Ｌｉ neutron ~ 14MeV peak IFMIF Overview Neutron Irradiation Field for Fusion Materials Post Irradiation Examination Test Facilities Deuteron Accelerators Li-Target Loops Li-Target Assembly E d : 40 or 32MeV, I d : 250mA (=10MW max) Flux-volume: 500 cm n/cm 2 /s)

Oct.18, Issues Related to Neutronics and Radiation Safety Li+d source neutron characteristics (not only TTY for 40 and 32 MeV, DDY is preferable) Materials+d source neutron characteristics (due to beam loss along accelerator and beam line) Deuteron induced radio-activities (Ed<40MeV) Neutron induced radio-activities (Ed<50~60MeV) Neutron shielding and streaming from Test Cell Handling of radioactive materials during operation (lithium, irradiation sample, target assembly, etc.)

Oct.18, Source Neutron Characteristics (1)

Oct.18, Source Neutron Characteristics (2) Extend to Lower Energy Part & at Higher Deuteron Energy up to 40 MeV Recent Measurement at CYRIC (Tohoku Univ., 2000)

Oct.18, Source Neutron Characteristics (3)

Oct.18, Source Neutron Characteristics (4)

Oct.18, Deuteron Induced Radioactivity (1) Recent Measurement at CYRIC (Tohoku Univ., 2000) D.L.Johnson et al.

Oct.18, Deuteron Induced Radioactivity (2)

Oct.18, Deuteron Induced Radioactivity (3) Relative Importance of D-induced radio-activities in Li

Oct.18, Requirements for Neutron Nuclear Data Spectrum Calculation Neutron DDX (especially at low energy and larger scattering angles) Nuclear Heating Calculation Photon production Charged particle production Activation Calculation Long-lived residual production Sequential multi-step reaction process UNIVERSAL REQUESTS IN USE FOR IFMIF NEUTRONICS PROBLEMS e.g. (n,2n), (n,3n) and (n,Xn) (where X=charged particle) processes are important in some calculations (Neutron cross sections up to 50~60 MeV)

Oct.18, Status of Neutron Nuclear Data (n,2n) : Generally good situation except for Be, candidate of multiplier material. (n,3n) : Generally worse. Heavily relied on model calculations. Experimental consistency check is recommended. (n,pn) : Situation is better. Systematic measurement to separate (n,d) process is lacked. (n,  n) : Comparatively worse. No systematic study is found. Partial DDX information for each channel is necessary to establish the clear systematic understanding about channel branching, though its measurement is extremely difficult. Theoretical support calculation which excludes the excessive model parameters is inevitable. Continued systematical measurements of the above reaction cross sections at JAERI/FNS and the other facilities (esp. at higher than 14 MeV) is strongly desired and the results are much useful.

Oct.18, Summary 1.Neutron source characteristics are relatively well-known. 2.Detailed analyses to deduce Double-Differential Yields for mono-energetic deuterons based on the correct theoretical interpretation are needed. 3.Deuteron induced activities might be measured at each laboratory, however, these data are not available in a systematical form. 4.Neutron induced activities are