1 SAFERIB EURISOL DS WP5 Progress Report CERN-RP: Mariano Menna, Jerôme Desarzens, Thomas Otto

SAFERIB / EURISOL 05/20082 SAFERIB Overview Activity content in UC- targets Th. OttoData available and used, report pending Shielding of hotcellTh. OttoReport written Activation of target components Th. Otto, M. Magistris Various reports and proceedings available Environmental impact of target incidents M. Menna, P. Vojtyla Report under review External dose rate coefficients for exotics J. DesarzensReport in preparation Ground activation at ISOLDE (-> EURISOL) Th. OttoIn progress

SAFERIB / EURISOL 05/20083 EURISOL Overview Validation of Monte-Carlo isotope production code M. FelciniReport, Proceedings Pohang Shielding of MMW targetM. FelciniProceedings Pohang Various work on old MMW target Th. Otto, M. Felcini obsolete Shielding of 100 kW target Th. OttoReport Ground activation at EURISOL LINAC Th. OttoReport under review Streaming of radiation in MAFF-tube Th. OttoPreliminary study terminated, continue with “real” geometry Ground activation at 100 kW/ MMW targets Th. OttoIn Progress Dose rate estimates for work in Linac tunnel Th. OttoPreliminary study terminated, improvements in progress

SAFERIB / EURISOL 05/20084 SAFERIB: Environmental Impact Study Assumption: 1 UC target (10 19 protons, 3 months post-irradiation) fully vapourised. Dose to member of public (living next to CERN): under unfavourable conditions, approx. 1 mSv 85 % of dose provoked by volatile Po-isotopes Report under Review Some steps need to be taken in CERN’s interim storage for ISOLDE targets.

SAFERIB / EURISOL 05/20085 SAFERIB: External dose rate coefficients External dose rate coefficients (“Gamma-factors”) permit a simple estimate of H*(10) for a given activity Usually, only istopes with t 1/2 > 2 min. listed Calculated also for exotic nuclides, possibly produced at ISOL facilities Use decay data from NuDat 2.4 from NNDC, fluence-to dose-coefficients from ICRP 74 Approach to beta-decay: describe spectrum with statistical factor and Fermi-function F(Z,W)

SAFERIB / EURISOL 05/20086 EURISOL: Soil activation, water contamination Use conservative screening approach from Bull, Baker et al. (Fermilab & SSC): saturation activity leached into soil moisture (no additional dilution) Model: EURISOL LINAC, loss rate 1 W m -1 Compare results with limits and guidelines, from different countries

SAFERIB / EURISOL 05/20087 EURISOL: Soil activation, water contamination 3 H-activation of soil at 500-MeV-point “Activation layer” (3 m thick) contains 99.9 % of activation products

SAFERIB / EURISOL 05/20088 EURISOL: Soil activation, water contamination 3 H in water from activation layer probably acceptable, 22 Na content inadmissibly high “Underground environment” must be protected when new accelerator projects are planned. Extend the method to target stations: 1 kW (SAFERIB)– 100 kW - MMW Elaborate guidelines for target area construction

SAFERIB / EURISOL 05/20089 EURISOL: Radiation streaming Dose rate in duct with  =8.5 – 16.7 cm Dose rate scales as d/A 1/3: curves for different diameters fall approximately together For obstacle in duct: streaming comparable to duct of smaller diameter, if target off-axis Will study streaming in the MAFF-like target station, plans just received.

SAFERIB / EURISOL 05/ EURISOL: 1 W/m loss and “hands-on” maintenance 1 W/m loss power corresponds to a fractional loss of m -1 at a 1 MW accelerator ! Question to accelerator engineers: Is it achievable ? In LINACs, on average, yes. Question to RP staff: Is it ALARA ? Depends on time and duration of the access. What does “hands-on” mean exactly? Two possible answers: “We can do the job without worrying about radiation” “No robots or manipulators are needed”

SAFERIB / EURISOL 05/ For example: E = 1 GeV, loss 1 W/m 8 months of operation 1 week wait (typical for begin of shutdown) Ambient dose rate is everywhere H*(10) > 100  Sv/h Close to vacuum chamber H*(10) > 1 mSv/h “Hands-on ?”

SAFERIB / EURISOL 05/ Energy dependence 40 cm is worker’s distance during repair work Highest activation at proton energies of several 100 MeV Simple Explanation: Low E: protons stopped, dE/dx high, high activation High E: protons pass through material, small dE/dx Ambient dose rate H*(10) in 40 cm from accelerator for linear loss of 1 W/m

SAFERIB / EURISOL 05/ What remains to be done ? SAFERIB: Finish last 2 reports Contribute to final report with consolidated results EURISOL: Soil activation at LINAC Soil activation at target stations Streaming in MAFF tube with realistic design Dose from activated components during maintenance