Feedback on two irradiation testing projects Emergency lights and TETRA system Elisa Guillermain elisa.guillermain@cern.ch

Material Irradiation testing - WorkFlow Identification of dose levels : Where is the material installation area(s) ? How long is it expected to live ? Irradiation test → Accelerated ageing test. Definition of the irradiation test parameters and specification. Irradiation type and dosimetry, passive or active test, etc… Choice of the suitable irradiation facility. In-house (CHARM, CC60,…) or external (Fraunhofer INT, Ionisos,…). Material characterization : Tests and analysis. Conclusions : Can the material be installed or an alternative must be find ? R2E team support at all steps ! Support of the Monitoring and Calculation Working Group !

Project example 1 : Emergency lights

Emergency lights : Overview Current technology is robust but obsolete – will be discontinued. Need to have a replacement solution ! New emergency lighting system : Two types of lights : Comatelec specifically designed for wall mounting. Thorlux for ceilings. Specifications are similar. Parts potentially sensitive to radiation : Power supply : Modified for SEE insensitivity (still need to be fully assessed). KT fund and CERN open hardware license. LEDs. Plastic or glass parts (windows).

Emergency lights : Irradiation tests history Test of the full system : In CNGS. Gammas (Fraunhofer INT) – December 2013. Passive tests, up to 100 kGy. Darkening of the windows. Decrease of the light flux. Neutrons (CEA) – June 2013. 5x1014 neutron eq/cm2. Difficulties for the characterization test. Test of parts : At CHARM : Bridge rectifier of the new power supply was tested at CHARM. Resistant up to at least 30 Gy (parasitic mode : low total dose…).

Emergency lights : Irradiation tests history On-going real condition tests : The old technology was removed and replaced by the new technology during LS1: In LHC Pt 7 : Wall emergency lights (approx. 1.4 m height every 14 m). Lights are ON when tunnel is closed. In TDC2 and TCC2 : Wall emergency lights (approx. 1.4 m height) and ceiling emergency lights. Half of the lights are OFF when tunnel is closed. LED lifetime increase is expected.

Emergency lights: Requests to MC WG The light shall withstand at least 5-years LHC dose. Doses accumulated since their installation (LS1) ? Expected doses for the next years ? The lights are not at beam level (BLM) nor RadMon locations (below beam line), but on the walls : How to assess the dose at the tunnel walls from the doses at beam level ? Feedback from MC WG will help determining the parameters and condition for the foreseen additional irradiation tests.

Project example 2 : TETRA system

TETRA beacons : Overview TETRA emergency communication system : http://information-technology.web.cern.ch/services/Radio-Communication Digital communication and geolocation system : In both surface and underground CERN areas. Radio (fire brigade, security guards, maintenance and operational teams). Over 1000 beacons for geolocation. Beacons : Contains electronics. Modified for SEE insensitivity(still need to be fully assessed). Battery powered (LiSOCl²). TETRA system was installed during LS1 in the whole accelerator chain.

TETRA beacons : Irradiation tests history Irradiation test already preformed : In CNGS (CNRAD), up to 154 Gy. At Fraunhofer INT (gammas) : Failure at 336 Gy with 3.2 Gy/h. They functioned again after annealing. Output of irradiation tests : The beacons resisted up to few hundred Gy only. Most critical in SPS. Consider development of radiation tolerant beacons ? It is unsure if failure is due to the batteries or the beacons themselves (power consumption increase ?).

TETRA beacons : Requests to MC WG System installed during LS1 in accelerators (inner walls of tunnels). In SPS, 1/3 of the beacons stopped working. Location of the damaged beacons is known. Doses accumulated since their installation (LS1) ? Expected doses for the next years ? How to assess the dose at the tunnel walls from the doses at beam level ? Feedback from MC WG will help determining the parameters and condition for the foreseen additional irradiation tests.

Conclusion The two systems described are safety related : It is crucial to assess their lifetime. Feedbacks and inputs from the MC WG are valuable for specifying irradiation tests and assessing the life time of material and devices depending on their installation area(s). Difficulties : BLM, RadMon, RPL are not at the walls or ceilings. How to estimate the accumulated dose at the walls / ceiling from these measurements ? Inputs from the Fluka Team ? The outputs from these two request will be useful in the frame of many other projects.

Thanks for your attention !