Tas neutral beam absorber for lhc at cern




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TAS neutral beam absorber for LHC at CERN

Safety note


Vanecek/Hoyer/Bercovitz 28 June 2000
The TAS consists of three major assemblies: they are the copper absorber, vacuum chamber, and support jacks. The copper absorber is fabricated in 2 halves. The 2 halves of the copper absorber are bolted together with 6 (M18) screws. The vacuum chambers are secured by the lower and upper halves of the copper absorber. The support jacks, with support rod hold the copper absorber assembly rigidly in the vertical and horizontal position. The support rods are rigidly supported at the copper absorber and hinged at the jack. The total weight of the TAS is 3200 kg.

1) Lifting


As can be seen in figure 1, there is 1 hoist ring in the center of the copper absorber assembly. This is an ADB safety hoist ring part no 34103 or equivalent. They are rated at 4200 kg each. See figure 2, below. After assembly, the TAS assembly will be lifted into the CERN tunnel with a CERN crane onto a tunnel transfer carriage. The transporter will move the TAS assemble to designated cavern.




Part No.

Rated Load

(kg)


A

mm


B

mm


C

mm


D

mm


E

mm


F

mm


G

mm


K

mm


M

mm


Rec.

Torq.


N-m

Wt.

(kg)


34103

4200

35.6

129.5

52.1

25.4

38

177.8

M24 x

3.0


71.4

78.3

311

3.3







































Figure 2


Safety Hoist Ring
This chart from American Drill Bushing is shown for illustrative purposes. There are half a dozen equivalent brands. The hoist rings will have a safety factor of five. They will be supplied by the vendor with proof test certs. NDT will be performed after proof loading.
2) Seismic considerations
2a) Seismic considerations at LBNL: LBNL requirements: 0.7 g Horizontal and 0.35 g Vertical. Here the concern exists when the TAS assembly is supported in the TAS assembly fixture. The higher stress conditions exist in the vertical support rods.

Stress proof or equal load per rod Stress


Half the absorbers weight 126 MPa

Bending load 430 MPa

Max. Operational load 556 MPa

Additional vertical load due to 0.35 g earthquake load 11 MPa


Max. Load under operational conditions 600 MPa
Stress proof yeald strength 758 MPa

Stress proof ultimate strength 889 MPa


Safety factor based on ultimate strength is 1.5
2b) Seismic considerations at CERN: CERN requirements: 0.15 g Horizontal and 0.11 g Vertical. Since the LBNL seismic requirements are a factor of 3-5 greater then the CEAN requirements, the CERN requirements are met.

3) Temperature considerations


The vacuum chamber of the TAS must be baked out at 200°C. During bakeout, the copper absorber will be wrapped in aluminum foil and then wrapped in a heat blanket. Surface temperature is not expected to reach a temperature of 55°C. The TAS will be uncovered after the heating cycle. To prevent burn danger, it is proposed that personnel safety barriers be positioned around the TAS during bakeout.





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