Loss in TED Loss in magnet Loss in iron rod Assessment of the production of airborne radioactivity caused by various beam loss scenarios in the SPS

Table: Production of the airborne radioactivity (in Bq, no decay considered) per lost proton. dacay time scenario0s300s3600s TED 450 GeV/c4.39E E E-25 TED 26 GeV/c4.55E E E-26 TED 14 GeV/c3.11E E E-26 magnet 450GeV/c1.76E E E-24 magnet 26GeV/c1.50E E E-25 magnet 14GeV/c9.19E E E-26 rod 450 GeV/c8.21E E E-24 rod 26 GeV/c8.68E E E-25 rod 14 GeV/c5.34E E E-25 Dose in Sv given to the critical group at TT20 per lost proton decay time scenario0s300s3600s TED 450 GeV/c magnet 450GeV/c rod 450 GeV/c Dose in uSv given to the critical group normalized to 1.66E19 protons in case air is continuously released All Sv/Bq factors calculated by P. Vojtyla

Relative comparison of the dose to public given by the different beam loss scenarios calculated for a time span between production and release of 0 s.

Dose per lost proton (450 GeV/c) which is given to the critical group as a function of the time span between the production of the isotopes and their release. Minimum time required between nuclei production and air release to reduce dose to public to 10 uSv in case of a continuous air release.

Accidental release of air over 1 day of operation (1E17 protons) The critical group of the public will get a dose of 18.6 uSv in case a decay time of 0 seconds is assumed. For a decay time of 300 s the dose to the critical group will go down 8.3 uSv. In order to lower the risk of an unnecessary release of radioactive air to the environment, the emergency air release option of the system should be blocked during beam-on periods. Functioning of ventilation system (e.g.: electricity supply) should be only possible when interlock of extraction is activated. Same Bq production rates for iron rod per proton but short term Bq-to-Sv release factors are considered to calculate dose if (beam interlock == true)  {electricity to emergency system} if (beam interlock == false)  {no electricity to emergency system)

Further analysis of composition of radioactive air Table: Dose to public (Sv) per lost proton calculated for the three loss scenarios at 450 GeV/c. The time between the production of the radioactive isotopes and their release is assumed to be of 0 s. Isotopes which contribute more than 5 % to the total dose received by the critical group are highlighted in the table.

Summary of all isotopes contributing more than 5 % to the total dose seen given to the critical group of the public  Key elements contributing dose to public Be-7, C-11, N-13, O-14, O-15, Al-28, P-35, Cl-39 and Ar-41.  Measurement system which is used to measures air release must be reliable in measuring these key elements

Measurement system used to measure air releases at the SPS Differential Ionization chamber system Two chambers of same type: one chamber is flooded with fresh air the second chamber with air whose activity has to be measured Difference gives the result of activity produced Calibration factor used: 1.565E-18 A/(Bq/m3) Reliability of calibration factor unknown Simulation of chamber response is required to check calibration factor

Simulation of differential chamber Chamber is filled with air List of radioactive isotopes is provided with its contribution to the total activity Isotope is chosen randomly according to their contribution Starting position is chosen homogeneously in the air volume (randomly) Energy deposition is calculated within the air volume of the active part of the chamber Conversion into e - /Ion + pairs produced  current (A) per Bq  calculated calibration factor in A/(Bq/m3).

Results for single isotopes elementsimulated measured ratio sim/meas A/(Bq/m3)A/(uCi/m3) H33.23E E E E+00 C112.38E E-14 C141.96E E E E-01 N132.24E E-14 O141.98E E-14 O152.00E E-14 Al E E-14 P E E-14 Cl E E-14 Ar412.24E E-14 Kr852.45E E E E+00 Reliability of simulation: ????  For elements where we have information from the manufacturer the simulation results agree within 20 %.

Comparison between the simulated (“real”) calibration factor of the given isotopes and the calibration factor of 1,57E-18 A/(Bq/m 3 ) which is currently used to determine the air activity released. ElementSimulated Measured/real activity A/(Bq/m3) H33.23E C112.38E C141.96E N132.24E O141.98E O152.00E Al281.78E P351.85E Cl391.97E Ar412.24E Kr852.45E Be-7, which emits only a gamma is strongly underestimated by used calibration factor Strongly underestimated } Overestimated by used calibration factor

Simulated (“real”) calibration factors of the isotope mixtures calculated for five beam loss situations. The resulting calibration factors are compared to the used measurement calibration factor of 1.57E-18 A/(Bq/m 3 ). Situationsimulated measured/simul ated activity A/(Bq/m3) magnet 450GeV 0s decay2.05E iron rod 450 GeV 0s decay2.04E TED 450GeV 0s decay2.07E TED 450GeV 300s decay2.15E TED 450GeV 3600s decay2.21E Measurement of the isotope mixture overestimates the Bq released by at least 30 %

Sv/Bq calibration factor applied to measured Bq For Air releases in Switzerland: 3.4E-19 Sv/Bq For Air releases in France: 5.5E-19 Sv/Bq Used Sv/Bq factor at TT20 is conservative for all scenarios Calculation of Sv/Bq factor for the given long term release example of TT20 Obtained byP. Vojtyla factors are conservative Check whether used factors of 5.5E-19 Sv/Bq if conservative for TT20

For the aforementioned situations the used chamber calibration factor A/(Bq/m 3 ) is conservative + The Sv/Bq factor is conservative (only proven at TT20) Measurement results can be seen as conservative approach to the real dose given to critical group of the public Air release measurement results of 2004 will be used to extrapolate air releases for the future SPS operation

Determination of the correlation between radioactivity released and the intensity of high-energy particles in the SPS in 2004 Release point Activity/primary proton Dose/primary proton GBq/protonSv/proton TT10 (normalized per proton sent to beam dump)1.42E-154.8E-25 TT10 (normalized to all accelerated particles – high- energy dump operation influence) 2.50E-168.5E-26 TT60 (normalized to all accelerated particles)1.85E E-26 TT60 (normalized to particles extracted to West Area)1.85E E-25 BA3 (normalized to all accelerated particles)2.15E E-26 BA5 (normalized to all accelerated particles)5.69E E-26 TT20 (normalized to all accelerated particles)1.47E E-27 TT20 (normalized to particles extracted to North Area)1.00E E-27 Data are based on: Airborne radioactivity: Differential chamber read-out (background corrected) Beam intensities: \\cern.ch\dfs\Divisions\SL\DIV_SL\STAT\SPSSTAT\PROTONS\2004\Tab\Stats Protons 2004.xls and\\cern.ch\dfs\Divisions\SL\DIV_SL\STAT\SPSSTAT\PROTONS\2004\Tab\Stats Protons 2004.xls Intensity of High-energy beam on dump between July and September: Joerg Wenninger

Back test of calculated factors for TT10 releases Factors are based on data between July and September Calculated result for whole year versus measured result for whole year 0.5 uSv (dump) uSv (others) =1.62 uSv (total) 1.54 uSv (measured by chambers)

Release pointProtons/yearcomments TT10 (beam dump operation at 400 GeV/c) 1.2E18Protons on dump TT10 (normal acceleration up to 400 GeV/c) 6.1E19Protons in machine TT60 (normal acceleration up to 400 GeV/c) 6.1E19Protons in machine TT60 (extraction:10 LHC fillings per day) <1.0E18Protons to LHC BA3 (normal acceleration up to 400 GeV/c) 6.1E19Protons in machine BA5 (normal acceleration up to 400 GeV/c) 6.1E19Protons in machine TT20 1.6E19Protons to North Area Release pointActivityDose GBq/yearSv/year TT10 (beam dump operation)1.70E+03 = 1.7E E-07 = 5.8E-06 TT10 (normal acceleration up to 400 GeV)1.53E E-06 TT60 (normal acceleration up to 400 GeV)1.13E E-07 TT60 (200 days of 10 LHC fillings per day)1.85E E-08 BA3 (no Point 4 extraction considered)1.31E E-07 BA5 (no Point 4 extraction considered)3.47E E-06 TT202.35E E-07 Intensities used for extrapolations to 2006 and later Results based on pure extrapolations from 2004 to 2006 and later

More accurate calculations to obtain dose to public TT10 releases: additional losses at low energies during CNGS operation (see Tables in our report) fixed target operation (extraction at Point 2) causes higher releases at TT10 than CNGS operation Main additional factors considered TT60 releases: slow extraction at Point 6 is replaced by fast extraction to LHC Point 3 and Point 5: additional releases caused by fast extraction at Point 4

Release pointActivityDoseComments GBq/yearSv/year TT E E-06Conservative assumption TT E E-06 Assuming that during FT operation the main radioactivity at TT10 comes from slow extraction at Point 2 TT E E-07 Correlation factor is based on slow extraction and total number on protons accelerated (very conservative) TT60 52E-09 Based on the assumption that dose is caused only by losses at fast extraction BA3 8.36E E-06Conservative assumption (including all Point 4 air) BA5 1.05E E-06Conservative assumption (including all Point 4 air) TT E E-07 Final assessment

Water activation Main water activation in 2004 came from TDC2/TCC2 Water activation released in 2004 caused 50 nSv to critical group of the public Conservative assumption: water activation scales with the intensity of the SPS (factor 5) Dose in 2006 and later given to critical group of the public by water release: 250 nSv/year

Sextant 1Sextant 2Sextant 3Sextant 4Sextant 5Sextant 6 Activation in the SPS Remnant dose rate 30 h after the beginning of the shutdown in 2004.

Remnant dose rate at Point 1

Long term dose rate after 6 month at hottest monitor position (TIDV): 2 mSv/h 2004: 1E18 high-energy particles on dump 2006: 1.2E18 high energy particles on dump Long term dose rate after 6 month at hottest monitor position: < 3 mSv/h Dose caused mainly by high- energy dump operation

Point 2 Extraction to North Area Due to different operation scheme Compared to Point 1 much lower remnant dose rate after beam off.

Long term dose rate in Point 2 Long term dose rate after 6 month at hottest monitor position (ZS): 1.2 mSv/h 2004: 8.8E18 high-energy particles extracted 2006 and later: 1.6E19 high-energy particles extracted:  dose rate will double at the extraction equipment

Long term dose rate in Point 6 Dose rate at the extraction equipment after six month of cooling will be much lower ( ~ factor 50) than the one seen during slow extraction New loss point at Point 4 Losses 4.3%below 0.5% Number of protons extracted8.8E184.5E19 Lost protons3.8E172.3E17 Comparison between losses at Point 2 (2004) and Point 4 Point 2 Point4 Remnant dose in Point 4 will be lower than the one in Point 2 in 2004 (similar equipment assumed)