Datte, P

Dauffy, L

Eckart, M

Jackson, M

Khater, H

UNT (University of North Texas) Digital Library

LLNL-CONF-497277Assessment of radiation effects ondiagnostics and electronic devices in theNational Ignition FacilityH. Khater, L. Dauffy, P. Datte, M. Eckart, M.JacksonSeptember 1, 2011The 7th International Conference on Inertial Fusion Sciencesand ApplicationsBordeaux, FranceSeptember 12, 2011 through September 16, 2011Disclaimer  This document was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor Lawrence Livermore National Security, LLC, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or Lawrence Livermore National Security, LLC. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or Lawrence Livermore National Security, LLC, and shall not be used for advertising or product endorsement purposes.  Experiments resulting in a significant neutron yield are expected in 2012 at the National Ignition Facility (NIF). A wide range of diagnostics will be used to measure several parameters of implosion such as the core and fuel shape, temperatures and densities, and neutron yield. These diagnostics must be able to operate properly during several types of shots with varying neutron yields. Components like CCD cameras and several electronic devices are sensitive to the neutron and gamma backgrounds expected during shots. Fusion neutrons generated by fuel burn and secondary neutrons resulting from the fusion neutrons interaction with structures present inside and outside the Target Chamber contribute to the neutron background. A detailed model has been developed for the NIF facility and it includes most of the major structures inside the Target Bay. The model has been utilized in the simulation of expected neutron and gamma fluences throughout the NIF. Radiation damage to electronic devices in terms of rad-Si has also been calculated for large number of locations inside the facility. These data are being used to provide options for shielding of critical diagnostics and electronics devices to ensure that high precision measurements of neutrons and gammas will be possible during high yield shots. H. Khater, L. Dauffy, P. Datte, M. Eckart, and M. JacksonAssessment of Radiation Effects on Diagnosticsand Electronic Devices in the National Ignition FacilitySectional View of the Target BayNuclear Diagnostics at NIFNTOF-4.5 DT-LO(64,309)NTOF-3.9 DSF(64,275)NTOF-4.5 BT(64,253)NTOF-20 Equator(90,174) NTOF-4.5 DT-Hi(64,330)NTOF-20 Alcove (116,316)WELL NADS(64,241) GRH(64,20)NAD 20 Copper (116,316)TARPOS (90,239)WRF/hGXI DIM(90,78)• Neutron yield• Ion Temperature• Target symmetry• Bang time• Plasma density MRS(77,320)NIF Target Bay Model90,79 DIM90,315 DIMCRYO TARPOSTARPOSTASPOSFFLEXMCNP Model of the TB EquatorNeutron Dose at the EquatorNeutron Fluence at the EquatorPer 20 MJAll energiesGamma Fluence at the EquatorPer 20 MJAll energiesGamma Dose at the EquatorPer 20 MJAll energiesPer 20 MJAll energiesComponents One event thresholds*(per device)SRAM, SDRAM, Microprocessor3-8x108 n/cm2DRAM 2x108 n/cm2SRAM 0.2-4x108 n/cm2Tektronix scopes 2-4x108 n/cm2Fluence Level to Initiate Upset*  50% probability of an upset (courtesy of Jim McNaney)Dose as a function of EnergyPixelinkDage is unshieldedLead ShieldingPoly ShieldingTCC10 rad_Si neutrons14 rad_Si gammaDose without shielding for a 20 MJ shot:195 rad_Si neutrons and 640 rad_Si gammaDouble Fold Need to add shielding in  the throatShielding Design for the Chamber Internal Viewing System (CIVS) CameraTarget Alignment System (TAS) is Removed Before High Yield Shots due to Difficulty of ShieldingnToF20 Electronics are Located in Low Radiation Background Environment outside the Target BayRadiation Mitigation Strategies• Reduce exposure by removing vulnerable electronics outside the Target bay before shots • Locate sensitive electronics in low radiation area outside the Target Bay• Provide additional shielding to allow  for certain electronics to stay inside the Target bay during high yield shots• Use radiation hardened systems that are capable of  surviving a challenging radiation environmentAlcove(90, 174) Port(116, 316 ) PortSwitchyard 2 Switchyard 1DetectorDetector Switchyard 1Switchyard 2AlcoveShielding Design for the Streaked Polar Instrumentation for Diagnosing Energetic Radiation (SPIDER)2” W surrounding CCD Camera4” Poly CartFloor Shielding:1” SS on the top12” poly in the middle1” SS on the bottomFluence at the CCD Location without Shielding Fluence at the CCD Location with ShieldingDose at Y=1017 NeutronsNeutrons=4.1 rad_SiPhotons=2.3 rad_SiNeutrons=0.04 rad_SiPhotons=0.32 rad_SiThe Goal is to limit the number of stars in the CCD camera by limiting the total dose per shot to <0.4 rad_Si9” Poly2.5” Pb

Assessment of radiation effects on diagnostics and electronic devices in the National Ignition Facility

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Assessment of radiation effects on diagnostics and electronic devices in the National Ignition Facility

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