EN-MEF
LTEX 01
nd
22 June 2009
LHC TUNNEL AND EXPERIMENTS STUDY GROUP
(LTEX)
Minutes of the first meeting held on 22nd June 2009
Present:
G. Arduini, O. Beltramello, N. Bacchetta, E. Bravin, L. Bruno, J. P.
Corso, J. Coupard, M. Deile, B. Delille, A. Di Mauro, R.
Dzhelyadin, S. Evrard, D. Lacarrère, M. Ferro-Luzzi, K. Foraz, M.
Gastal, M. Giovannozzi, M. Gruwé, A. Herty, P. Lepeule, D.
Macina (Chairperson), M. N. Minard, D. Mladenov, M. Nessi, N.
Oliveira, A.L. Perrot (Scientific secretary), E. Radermacher, G.
Roy, C. Schaefer, R. Veness, H. Vincke, R. Vuillermet, J.
Wenninger,
1.
MANDATE
(D. Macina)
D. Macina presented the mandate of the LTEX and its associated
website (http://en-dep.web.cern.ch/en-dep/Groups/MEF/LTEX/). She proposed to
run the study group on a 3 week period. The dates for the following meetings
are available on the website. The 1rst LTEX is dedicated to the work to be
performed in the LHC tunnel to protect the experimental caverns and
personnel from a ‘Sector 3-4 like’ incident.
2.
ATLAS CAVERN PROTECTION CAMPAIGN
(O. Beltramello)
O. Beltramello presented a comprehensive review of the ATLAS
campaign dedicated to the protection of the ATLAS cavern from “Sector 3-4
like incident”. The ATLAS campaign work should be finished by beginning of
August in order to meet the Machine Commissioning schedule. In particular
for what concerns the TAS protection she presented the design requirements
(sealing, 200K minimum temperature held by the structure, standing
overpressure of 110mbars, ALARA, adjustments, interfaces with the TAS
cradle and mono-bloc, interfaces with the beam pipe system). The protection
consists of a ‘dome’ easily dismountable to allow access to the TAS
environment (in particular to the patch-panel of the heaters used for the bake-
2
out) (see drawings). The work is done in collaboration with the EN-MEF
group: ATLAS is responsible for the design and procurement while EN-MEF
for the coordination and the installation. Both ATLAS and EN-MEF will take
part in the discussions concerning the ALARA issues for the design and the
installation of the TAS shielding.
The sealing of the TAS has triggered the question if the TAS will need to be
cooled during the high luminosity runs. In fact, a cooling system was foreseen
at the beginning but it was never made operational. To avoid extra work once
the environment will be highly radioactive, a cooling system will be designed
and implemented before the end of the current shutdown (project leader S.
Evrad, EN/MEF) and ready for operation whenever required. The following
improvements have been suggested:

Check if a ventilation system is needed during the bake-out to
avoid the removal of the domes in case of overheating;

Check the possibility of displacing the heater patch-panel into a
different area to limit the time spent in this zone highly radioactive
zone during the bake-out;

Check whether, for fixing the domes, bolts are the best choice
according to the ALARA principle (pressure clamps might be an
alternative solution).
Due to lack of time, it was agreed that the suggestions above will be
implemented during next shutdown if necessary.
Finally, E. Bravin noted that the sealing of the TAS will limit the air flow in
this zone which, being highly radioactive, might cause a problem both to the
equipment and the people working there. D. Macina and G. Roy will follow
up this issue with the CV group.
List of actions:
- O. Beltramello will provide to J P Corso (LHC integration team) the 3D
models of the TAS protection;
- O. Beltramello and S. Evrard will contact K. Foraz to schedule the activities.
- S. Evrard will contact A. Pardon for the calculation related to the TAS water
cooling (internal cooling);
- D. Macina will discuss with EN-CV group and G. Roy the ventilation issues
for the Q1-TAS zone;
- R. Veness will study if it is possible to relocate the heaters patch-panel;
- S. Evrard and D. Macina (MEF group) will discuss with RP the ALARA
procedure for the TAS protection installation;
- ATLAS TC and D. Macina will circulate the ATLAS TAS ECR;
3.
PROTECTING CMS CAVERN
(M. Gastal)
M. Gastal recalled the CMS TAS environment and system. In particular, he
addressed in detail the:
Modifications in the TAS region (deadline: end of September 2009):
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o Goals:
 Restrict TAS movements restriction in Z direction during
alignment
 Prevent TAS movement in case of a September 19th type of
incident
 Prevent a flow of He from the tunnel to propagate into the
UXC55
 Avoid having to stay in the vicinity of the TAS once it is
activated
o Limitations:
 Stay clear of vacuum equipment
 Keep a fixed point on tunnel side for TAS bake-out purposes
 Keep the air flow around TAS for cooling purposes
 Allow for a removal of the TAS during the phase 1 upgrade
with minimal radioprotection risks
 No machining in the tunnel if possible
The movement restriction in the Z direction can be achieved by
installing pins which provide a fixed point (see presentation). As far as it
concerns the seal of the TAS area, two options are presently under study:
- Option 1: it consists in installing an annular clapper valve a few mm
thick that allows air flow from UCX55 to tunnel while preventing air
flow from tunnel to UCX55 in case of 110mbar overpressure. This will
require no additional holes. The installation will be performed from the
tunnel side. It should take about 2 days per side. It was noted that the
clapper valve needs a minimum pressure to close. CMS should check
that for pressures below the one needed to close the clapper valve the
eventual He flow in the cavern is not dangerous for the personnel.
- Option 2 consists in sealing the TAS volume from the cavern side. In
this case the access will be more difficult because of the proximity of
the vacuum remote handling system. In addition, small leaks are still
possible through the TAS alignment and survey systems.
Sealing of all remaining openings (deadline: end of June)
The holes between the CSF and the FIN will have to be closed and withstand
110 mbar. This will be achieved using metal plates and blocks filled up with
concrete. The FIN doors will be bolted and the remaining gaps sealed. Finally,
all ducts cables and cable trays will be sealed to guarantee 20Pa overpressure
between the tunnel and UXC55.
Pressure resistant doors and ODH sensors (deadline: July 15)
Five blast doors will be installed in the CMS underground area to protect both
UXC55 and USC55 in case of massive He release in the tunnel (they sustain
110 mbar pressure).
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List of actions:
- M. Gastal will contact K. Foraz to define the time slots for the interventions
(TAS sealing) on the tunnel sides;
- CMS will determine the thickness of the clapper valve (TAS sealing) in view
of the He flow that could be tolerated between the tunnel and the cavern;
- CMS (M. Gastal) will provide to J P Corso (LHC integration team) the 3D
models of the TAS protection;
- CMS and D. Macina will circulate the CMS TAS ECR.
4.
PROTECTING THE ALICE CAVERN
(S. Evrard)
S. Evrard presented the schematic of the air flow path around Point 2,
recalled for Point 2 the data from the pressure matrix in case of incident as
calculated by the Safety Commission and the access conditions foreseen
during the powering tests of Sectors 1-2 and 2-3. The protection of the ALICE
caverns requires
 a new partition at the RB26 interface (able to stand 76 mbar),
 the reinforcement of doors (MAD in UP25 and doors in UL)
 sealing of the surveys holes.
S. Evrard ensures the coordination of all the related activities. The new
partition in RB26 will be implemented for the powering tests phase II (work
starts this week). As the ALICE cavern will not be He tight for powering tests
phase II, compensatory methods have to be implemented. ALICE proposes to
divide the cavern in sub-areas with different access conditions according to
the tests performed in the LHC tunnel. G. Roy and M. Gruwé commented that
this approach is not safe because it does not allow the CCC to know if
somebody is in the ‘dangerous’ sub-areas. A different approach should be
found. All the sealing activities work should be completed by the end of July
2009.
List of actions:
- ALICE management, G. Roy and S. Evrard will re-discuss the access
conditions in the cavern and the sub-areas definition in view to ensure a safe
evacuation when needed.
- ALICE (S. Evrard) will provide to J P Corso (LHC integration team) the 3D
models of the new shielding;
- S. Evrard will contact K. Foraz to check activities schedule.
- ALICE and D. Macina will circulate the ALICE ECR.
5.
PROTECTION OF UX85
(D. Lacarrère)
D. Lacarrère presented the LHCb cavern environment (see drawings).
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- RB84 area: in August 2008 and during June 2009 the tightness of the
shielding wall has been improved (metallic joints, joints filled d with PUR and
sealed with concrete). Calculations show a good the mechanical stability of
the first concrete shielding up to a pressure of 75 mbar(VELO side; EDMS
1005362/1). Further improvement is under discussion.
- RB86 area: Because of the amount of equipment and lack of access (e.g.
cables) in front of the hole of the MF4 wall, no action has yet been performed
to improve the tightness of this wall. The He leak rate and associated force
acting on the MF4 wall if a He leak occurs in the tunnel should be evaluated
as well as the consequences. The cryoline will be reinforced with metallic
sheets by the bottom. The sector door needs to be reinforced too. Discussion is
going on with the EN/HE group (I. Ruehl) to agree on the details of the reenforcement.
- D. Lacarrère asked if there will be any financial support from the Machine
for this tightness reinforcement work between the experimental caverns and
the tunnel.
List of actions:
- D. Lacarrère will ask the civil engineering group to check the mechanical
stability of the wall between the tunnel and the UJX (pressure of 40 mbar) and
the mechanical stability of the wall between US85 and UX85 (made of
SIPOREX concrete 20 cm thick).
- D. Lacarrère will give to G. Roy the technical specification of the PUR
material;
- LHCb (D. Lacarrère) will provide to J P Corso the 3D models;
- D. Lacarrère will contact K. Foraz to check activities schedule.
6.
TEMPORARY INSTALLATION OF LHCB CALORIMETER
MODULES IN RB84.
(R. Dzhelyadin)
LHCb proposes to temporarely install 2 ECAL modules in RB84 in
order to test their radiation resistance in a parasitic way during the LHC
operation. R. Dzhelyadin presented the motivations of the project, the location
of the detector and its support.
LHCb would like to install the detector this summer before the LHC closure.
During the long shutdown the detector would be removed, sent for
recalibration to SPS and then re-installed for the LHC operation. The
installation of the detector and its associated support is estimated to be less
than a day.
List of actions:
- D. Macina will present the project to the management (report to LMC) for
approval;
- LHCb and D. Lacarrère will provide to J P Corso (LHC integration team) the
3D drawings of the new equipement ;
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- LHCb and D. Macina will write an ECR to be circulated mid of July;
- LHCb will check the activation of the material and report on a potential
impact to the location of installation.
7.
NEXT LTEX MEETING
The next meeting of LTEX will be held at 11:00 on Monday 29 June 2009.
Anne Laure Perrot