Radiation In-Port Cross-Talks for ITER Port Diagnostics

This paper emphasizes the need of estimation of the mutual influence, called "cross-talk," for neutronic analyses of neighboring diagnostics systems shared by the same ITER port. Using examples of several diagnostic systems inserted inside the ITER Equatorial and Upper Port Plugs, we have demonstrated this mutual influence. Cross-talk effects have been shown by examining the radiation environment inside the port plug in terms of neutron energy spectra and Shut-Down Dose Rate (SDDR) inside the Port Interspace (PI) area. In-port cross-talk was investigated for the diagnostic systems deployed in two Equatorial Port Plugs (EPP) #17 and #8, and for the components of Upper Port Plug (UPP) #3. One example of in-port cross-talks is a gamma shadow effect of the Tritium and Deposit Monitor (TDM) shield block, which affects the SDDR inside the PI of EPP#17. Where the gamma radiation originated from the dominant radioactive sources of the irradiated structures of Core-Imaging X-ray Spectrometer (CIXS) is blocked by the TDM shield. Another example is an influence of neutron streaming along the Fast Ion Loss Detector (FILD) channel on the neutron energy spectra calculated in the Tangential Neutron Spectrometer (TNS) in EPP#8. For the example of UPP#3 with Charge eXchange Recombination Spectroscopy (CXRS-core), performed neutronic analysis identified excessive neutron streaming along the CXRS shutter, which must be reduced by further design iterations.