PS Ventilation system

Sylwia Wojnarska 1 20th September 2012

PS Ventilation system

Sylwia Wojnarska

20th September 2012

Sylwia Wojnarska 220th September 2012

Proton Synchrotron


Whole PS – run mode simulation


Whole PS – boundary conditions• Fresh air system – velocity inlet every second room, pressure outlet every

second room. Velocity sets up according to area of splited face. • Recirculation system – intels and outlets – velocity inlet with set up velocity

according to area.

Area (m2)-------------------------------- ----------in_air_2 0.61482739in_air_4 0.81921583in_air_6 0.72836363in_air_8 0.68267637in_air_cent 0.71500003in_recirculation_1 11.537246in_recirculation_1_1 13.384367in_recirculation_2 60.883862in_recirculation_2_1 52.48156out_air_1 0.82453477out_air_3 0.75095761out_air_5 0.73948205out_air_7 0.72835767out_recirculation_1 11.149982out_recirculation_1_1 11.442415out_recirculation_2 52.049496out_recirculation_2_1 50.719254---------------- ----------

Mass Flow Rate (kg/s)-------------------------------- ------- -------------in_air_2 1.3632222in_air_4 1.3648114in_air_6 1.3562098in_air_8 1.3631358in_air_cent 1.7254738in_recirculation_1 12.606733in_recirculation_1_1 14.625097in_recirculation_2 32.891009in_recirculation_2_1 28.351823out_air_1 -1.9642062out_air_3 -1.781264out_air_5 -1.7571575out_air_7 -1.7285475out_recirculation_1 -13.440202out_recirculation_1_1 -13.792701out_recirculation_2 -30.987697out_recirculation_2_1 -30.195736---------------- ------- -------------Net 3.6248281e-06

Average of Facet Values Velocity Magnitude (m/s) -------------------------------- -------------------- in_air_2 1.8099999 in_air_4 1.36 in_air_6 1.52 in_air_8 1.63 in_air_cent 1.97 in_recirculation_1 0.89200002 in_recirculation_1_1 0.89200002 in_recirculation_2 0.44100001 in_recirculation_2_1 0.44100001 out_air_1 2.0748243 out_air_3 2.0860803 out_air_5 2.0879047 out_air_7 2.0869453 out_recirculation_1 0.98400003 out_recirculation_1_1 0.98400003 out_recirculation_2 0.486 out_recirculation_2_1 0.486 ---------------- --------------------


Results of run mode simulation


Results – velocityVelocity in whole tunnel in crossection z=0.2m – just above the inlet of recirculation system


Results – velocityVelocity in whole tunnel in crossection z=1m – in the middle of the magnet


Results – velocityVelocity in whole tunnel in crossection z=2m – just above the magnet


Results – velocityVelocity in whole tunnel in crossection z=3m – in the high of inlets and outlets of fresh air system


Results – velocityVelocity in crossection of room number 1 – in the outlet of fresh air system


Results – velocityVelocity in crossection of room number 2 – in the inlet of fresh air system


Results – velocityVelocity in crossection of room number 4 – in the inlet of fresh air system


Results – velocityVelocity in crossection between room number 3 and room number 4


Results – velocityVelocity in crossection between room number 7 and room number 8


Results – velocityVelocity in crossection of central room – inlet of fresh air system


Results – velocityVoctors in crossection of the room number 1 – outlet of fresh air system


Results – velocityVoctors in crossection of the room number 8 – inlet of fresh air system


Results – velocityVoctors in crossection between room number 7 and room numer 8


Results – velocityVelocity in crossection of the galleries

kg/s kg/h m^3/hGallery-1 0,28338000 1020,1680 832,7902Gallery-2 0,09505980 342,2153 279,3594Gallery-3 0,42995289 1547,8304 1263,5350Gallery-4 -0,03034674 -109,2483 -89,1823Gallery-5 0,42435798 1527,6887 1247,0928Gallery-6 0,01660639 59,7830 48,8025Gallery-7 0,42672986 1536,2275 1254,0633Gallery-8 0,07966877 286,8076 234,1286

5070,5896


Results – pressurePressure in whole tunnel in crossection z=1m – in the middle of the magnet


Results – pressurePressure in whole tunnel in crossection z=2m – just above the magnet


Results – pressurePressure in the whole tunnel in crossection z=3m – in the high of inlets and outlets of fresh air system


Results – pressurePressure in crossection of room number 1 – outlet of fresh air system


Results – pressurePressure in crossection of room number 2 – inlet of fresh air system


Results – pressurePressure in crossection of room number 8 – inlet of fresh air system


Results – pressurePressure in crossection between room number 2 and room number 3


Results – pressurePressure in crossection between room number 7 and room number 8


Results – pressurePressure in crossection of central room – inlet of fresh air system


Activated air in PS tunnel


Activated air - ingredients

Pure air : N, O, Ar and CO2 → 39 radionuclides with half-lives longer than few seconds can be produced.

N and O → 3H, 7Be, 10Be, 11C, 13N, 14O and 15O, Carbon-1440Ar → Argon-41 When the half-life is short, the radionuclide decays before reaching the ventilation outlet and its activity decreases (e.g.14O, 15O).

The nitrogen and oxygen isotopes, 41Ar, Carbon-11 (occurs as 11CO and 11CO2 ) → gaseous form Tritium occurs as HT and HTO. Other radionuclides - 7Be, attach to aerosol particles.

Air contains also aerosol particles that can be activated directly → 24Na and 22Na.

Radioactive erosion and corrosion fragments transported by the ventilation system → 46Sc, 48V, 54Mn, 57Co, 58Co and 60Co.An advantage of closed air-handling units is that they can efficiently decrease the activity of short-lived radioactive gases and other radionuclides (multiple filtering).


Activated air – air release from PS tunnelThe PS tunnel is not equipped with a directed ventilation system with controlled flow and defined and monitored exhaust stacks. The PS tunnel is not hermetically sealed and the pressure corresponds to the external pressure. The balance of 40 000 m3h-1 of air is therefore displaced from the tunnel into the environment.Air in the PS tunnel is activated by accelerator operation. At a given time t, Ai signifies the rate of activity production. The normal radioactive decay law applies to all produced radioisotopes with activity Ai:

- change of the radioactivity in time due to decay

In every time unit, a portion -dV = V’dt of the total tunnel volume V is displaced into the environment. - change of the radioactivity in time due to volume displacement, with the air exchange rate

With these elements, the linear differential equation for the activity present in the tunnel is:

Within this model, the activity released into the environment per time unit is:

iRi

R

i At

tA,

iV

V

i At

tA

V

VV

'

)()()()(

,0,,0,tAAtAtAA

dt

tdAieffiiiViRii

i VRieffi ,,

VRi

Vi

effi

Vi

t

iVreli AAtAdt

tdA effi

,0,

,0,

1

,,

)()(


Activated air – air release from PS tunnelRadioactive isotopes produced in the PS by activation in air from beam losses. It is assumed that 10 % of the 7.82·1019 protons accelerated in the PS in a year are lost during extraction at a momentum of p = 14 GeV/c. The loss occurs in an unshielded location of the beam line (as for example the electrostatic septum in SS 31)

Isotope Radioactive Half-live

Annual release (Bq)

11C 20.38 m 1.12·1013

13N 9.96 m 1.40·1013

14O 70.59 s 1.24·1012

15O 2.03 m 1.17·1013

41Ar 1.83 h 5.19·1011

These release figures are used to calculate the dose to a member of the critical group. The contribution to their annual dose of radioactive air releases from the PS is estimated to be 1.8 μSv (maximum dose is 10 μSv).

SS 31 – Straight Section between the main magnet units, 31 – number of unit.


Activated air – air release from PS tunnelRadioactive air releases are grouped in 4 categories: tritium (3H), short-lived gases (11C, 13N, 14,15 O, 18F), aerosol with 7Be and aerosol with beta emitters. There is no directed ventilation in the PS, their concentration is measured at one point in the PS. The activity concentration is then multiplied with the volume of air expelled from the PS by the air-exchange system in order to estimate the radioactive releases.Comparing the releases estimated in this way with figures calculated according the model above, one finds that the calculation exceeds the measurement by a factor of 5 for short-lived gases and a factor of 10 for 7Be. This result is not surprising, because the smoke tests have shown that the air in the tunnel is not homogeneously mixed. In particular, radioactive air generated in SS 31 will be conducted in the direction opposite to the location of the air monitor.


Sylwia Wojnarska

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PS Ventilation system

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