Technical Specification
Long Baseline Neutrino
Facility & CERN Neutrino
Platform
https://edms.cern.ch/document/1543254
Document EDMS identifier:
Created: 25-Jul-15
1543254
Last Modified: 14-Sep-15
Rev. No.: 1.0
EHN1-Cold Cryostats Technical Requirements
Abstract
This report describes the current understanding of the EHN1 cryostats cold structure.
Prepared by:
Checked by:
To be approved by:
D. Mladenov PH/DT
M. Nessi DG/DI-DI
M. Nessi DG/DI-DI
M. Nessi DG/DI-DI
+++
+++
D. Smargianaki EN/MEF
+++
Distribution List
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History of Changes
Date
25 July 2015
Version Changes/Comments
1
First draft
Authors
Marzio Nessi
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Table of Contents
1 INTRODUCTION .................................................................................................................... 4
2 ACRONYMS AND ABBREVIATIONS ................................................................................... 5
3 GTT LICENCE AND AGREEMENT ....................................................................................... 5
4 OVERALL PROJECT REQUIREMENTS ............................................................................... 5
5 FE WARM CRYOSTAT DESIGN AND LAYOUT ................................................................... 9
5.1 Design concept and main characteristics .......................................................................................................................... 10
6 COLD GTT VESSEL ............................................................................................................ 10
7 GTT DELIVERABLES FOR THIS STUDY ........................................................................... 13
8 SUMMARY ........................................................................................................................... 14
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1
Introduction
The Project’s purpose of this document is to define the requirements, necessary to the
firm GTT (Gaztransport & Technigaz, 1 route de Versailles, 78470 St-Remy-lesChevreuse, France) to perform an engineering study for the implementation of two
membrane cryostats inside the support structure proposed by CERN. The two tanks will
contain liquid Argon (LAr) and two different Neutrino detectors. The overall dimension of
the cold vessel and the Fe support structure (warm vessel) will be the same for the two
cases.
The two cryostats will be mostly identical, except for the penetrations needed to bring in
signal, power, detector supports, detector elements and cryogenics.
The two detectors, WA105 double phase TPC (here labelled WA105) and DUNE single
phase TPC (here labelled protoDune) will be very different and based on two different
technical approaches. If successful these two technologies will be cloned on a much larger
size for the final LBNF/DUNE experiment.
In both cases the technology is based on Time Projection Chamber (LAr TPC). The
neutrinos interact with the nucleus of an Argon atom, the ionizing particles which will
result will be detected when traversing the active liquid argon contained in the dewar.
One requirement is that the purity of the liquid argon be very high, with (electronegative)
contaminants below the ppb (part-per-billion) level.
Compared to a standard storage tank, the application for CERN also demands that many
thousands of electrical signals be extracted from the dewar and brought outside of the
vessel via leak-tight feedthroughs. This requires a specific set of penetrations through the
vessel as “chimneys” interspersed by thermal insulation.
After the detailed investigation of various solution and in view of the large scale
extrapolation to thousands of m3 storages, the GST®
(GazStorage & Technigaz)
technology has been chosen: in addition to being adapted to cryogenic conditions it
ensures that the Argon (liquid or gas) is in contact only with stainless steel metal
surfaces. GST technology is strictly under licence by the GTT company. A cooperation
agreement between CERN and GTT for engineering studies has been signed in the
summer of 2015.
This document contains the general requirements for the project. In section x we outline
the deliverables we expect from this design study.
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2
Acronyms and Abbreviations
BOG : Boil-Off Gas
BOR : Boil-Off Rate
GST® : GazStorage & Technigaz
GTT : Gaztransport & Technigaz company : http://www.gtt.fr/fr/
LAH : High Level Alarm
LAHH : High High Level Alarm
LAL : Low Level Alarm
LALL : Low Low Level Alarm
LNG : Liquefied Natural Gas
MDLL : Maximum Design Liquid Level
DOL : Design Operating Level
LAr : Liquefied Argon
ArG : Argon Gas
PAH : High Pressure Alarm
PAHH : High High Pressure Alarm
PAL : Low Pressure Alarm
3
GTT Licence and Agreement
This document might contain information from testing, experience and know-how of GTT,
which are protected under the legal regime of undisclosed information, trade secret and
Copyright law. This document is strictly confidential and can not be copied or used
improperly.
The Cooperation Agreement, signed between GTT and CERN, contains all details of the
way the two partners will interact for the purpose of this study.
4
Overall Project Requirements
As mentioned above, the expected function is to store LAr under its liquid form at
atmospheric pressure or just above. The tank will be placed inside an existing CERN
experimental hall (CERN EHN1 building). This will require to store the LAr at a
temperature between 86.7 K and 87.7 K, at a pressure inside the tank of 950 < P < 1100
mbar. A special emphasis has been made on the thermal fluxes. They have to be
controlled and have to be kept under 5 W/m2 on the walls/floor in contact with liquid.
The penetration have been arranged by positions and diameters. (see Section 6). Most of
the penetrations are placed on the ceiling of the cryostat. They have been differentiated
into two main groups according to their function and the thermal stresses they will be
submitted to: whether they can be used to support the weight of the detector or not.
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For the detector installation purposes, an opening of limited dimension needs to be
foreseen (see section 6.1 and 6.4). For WA105, the opening is on the side wall, for
protoDUNE - on the cryostat ceiling. Once the detectors are installed both openings will be
permanently closed.
On one side wall, as low as possible, a special penetration has to be foreseen to connect
the extraction liquid argon pumps that will allow the liquid recirculation to an external
filtering system. For both solutions the penetration will be the same but placed in different
locations (see section 6.2).
Both detectors will be exposed at CERN to ionizing beams for calibration purposes. To
minimize the interaction of such particle beams with the dead material of the cryostat
structure and of the liquid argon external to the active volume of the detector, a special
beam pipe will be installed. Its position will be different for both detectors (see section
6.3).
Figure 1.1 : WA105 overall cryostat layout
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Figure 1.2 : protoDUNE overall cryostat layout
Both cryostats will be operational in the experimental hall (EHN1).
Figure 1.3 : experimental hall EHN1 layout
4.1.
Storage characteristics
The dimensions have been adapted in order to ensure that all crossing penetrations are
arranged, as requested and that there is enough space for maintenance.
a) The final inner volume is 8.500*8.548*8.548 (height*length*width): ~620 m3.
b) Tank capacity (liquid volume = ~0.96%) : ~600 m3
c) Residual Heat Input (RHI) : 5 W/m2
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d) Insulation density : 70 kg/m2 (PU Aged HFC245)
e) Insulation thickness (all included) : <=1 m (to be computed by GTT in order to
fulfil the required RHI)
f) Design pressure: Max 1350 mbar / Min 950 mbar. 1350 mbar for the case of a
cryogenics accidental condition.
g) Operating temperature : 86K-89K
4.2.
Vessels dimensions
The dimensions requirements are dictated by the need to provide to the detector an
active volume in excess of the 485 m3 of Lar, for the WA105 case. This means a
transversal internal dimension of the liquid/gas volume of width = 8548 mm, length =
8548 mm and height = 8500 mm.
As the cold vessel is based on the GTT membrane technology, the initial thermal
requirements call for an insulation thickness of 1002 mm, including the primary and
secondary membrane. The GTT membrane technology will provide a first and a second
level of containment. There is no requirement at this point to have an additional liquid
containment at the level of the warm steel structure. A stainless steel skin of 6 mm
thickness just behind the insulation will provide an effective gas enclosure, which will
allow controlling the argon atmosphere inside the insulation volume.
The exact properties and dimensions of the cold vessel + insulation are part of this design
study.
Figure 2 : Overall dimensions
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Taking into account that the thickness of the insulation is ~1000 mm, and the thickness
of the primary membrane is 2 mm, then the required internal dimensions between the 6
mm stainless steel plates shall be 10552 mm x 10552 mm x 10504 mm (L x W x H).
The stainless steel plates are directly welded to the IPE600 beams. Therefore the total
external dimensions of the structure are 11764 mm x 11764 mm x 11716 mm (L x W x
H).
The dimensions are also presented in the table below:
Length [mm]
Width [mm]
Height [mm]
8548
8548
8500
SS Plate Internal Dimensions
10552
10552
10504
External Dimensions of the Structure
11764
11764
11716
Membrane Flat Internal dimensions
In Figure 2, a front cut of the structure with the dimensions shown on it is presented. The
membrane flat internal dimension do not include the space used by the SS cold
membrane corrugation.
In case GTT proves with this study that more than 1000mm of insulation are needed to
reach 5W/m2, the external dimension of the structure will be adapted, keeping the
membrane internal dimension the same.
5
Fe warm cryostat design and layout
Figure 3 : Warm vessel layout, showing the various major components
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5.1
Design concept and main characteristics
The steel warm structure represents the mechanical support of the inner membrane cold
cryostat and its insulation.
It consists of vertical beams alternated with a web of metal frames, capable to stand the
hydrostatic pressure of the liquid argon, the pressure of the gas volumes and all possible
external constraints.
Inside the steel structure, a skin of stainless plates is TIG-welded, such to provide a gas
barrier to the outside.
The main requirement is that this mechanical structure just sits on top of the concrete
floor of the building without bolting it to the floor, with no additional point of contact or
requirements to the building side walls.
The top of the cryostat metallic structure will be accessible for installation of the
detectors, the electrical/signal feed-through, the detector supports and other cryogenics
services.
The design and structural analysis of the warm support structure including the 6 mm SS
gas containment membrane is not a part of this study and has to be treated as a CERN
deliverable.
All necessary information can be found in https://edms.cern.ch/document/1531438
The 3d detailed cad model is visible in https://edms.cern.ch/document/1531439
Prior to installation of the GTT insulation and cold liquid membranes, the gas tightness of
the SS 6m membrane will be qualified by CERN through:
-
Dye penetrant analysis
Local vacuum bags techniques
He leaks sniffing detection
at the level of the natural He present in the atmosphere (~2-3 10-6 mbar/l/sec) and a
report will be presented to GTT.
6
Cold GTT Vessel
Inside the warm support structure, which includes the Stainless Steel gas enclosure
membrane, the GTT cold vessel will be installed. It consists of a thermal insulation, a
primary corrugated Stainless Steel membrane, as well as a secondary thin membrane, to
provide primary and secondary liquid containment. The insulation is instrumented with
gas inlets, outlets, temperature and pressure sensors.
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Specific penetrations required by the Neutrino application:
6.1. TCO (Technical Construction Opening)
A dedicated access window will be necessary to install the detector in the
WA105 case. This means that no insulation of membrane can be installed at the
beginning in this location. Once the installation has been finished, the opening
should be definitively closed, insulation and membranes should be installed and
welded in place.
The dimension to consider is an opening of 1340mm x 3830mm on a side wall
for WA105, compatible with the layout of the existing structural external beams
(see figure 4).
Figure 4 : front view of the TCO for the WA105 cryostat
6.2. LAr pump penetration
To keep the high level of purity required, an external pump is connected
one side to the bottom of the liquid, through a dedicated system of
valves. This penetration requires a local modification of the insulation
and the SS primary membrane, and will be a crossing tube with diameter
mm.
on the
safety
panels
of 168
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6.3. Beam pipe penetration
Once constructed, these detectors will be exposed to ionizing particle beams at
CERN in the SPS accelerator. To avoid an important absorption of the energy of
these particles in the dead material of the cryostat and its insulation, we need to
insert a beam pipe which will remove a large fraction of this unnecessary
material. In both cases, the beam pipe will be placed in different positions. Such
a penetration requires a local modification of the insulation panels and the SS
primary membrane. Pipe dimension : 250 mm in diameter
6.4. Roof signal, services and supports penetrations
The penetrations on the roof of the cryostat will be different for the two cases.
Two 3D cad models will describe in detail the number, position and diameter of
each penetration.
WA105:
see 3D CAD model to identify all positions:
https://edms.cern.ch/document/1543239
Penetrations:
Anode Suspension FTs:
Field cage suspension FTs:
Signal chimney FTs:
Slow control chimneys:
HV FT:
Manhole:
Cryogenic pipes - roof
Cryogenic pipes – side
N.
N.
N.
N.
N.
N.
12, crossing
16, crossing
12, crossing
4, crossing
1, crossing
1, crossing
tube
tube
tube
tube
tube
tube
diameter
diameter
diameter
diameter
diameter
diameter
40 mm
80 mm
277 mm
80 mm
156 mm
609 mm
N. 4, crossing tube diameter
N. 7, crossing tube diameter
N. 5, crossing tube diameter
304 mm
152 mm
76 mm
N. 2, crossing tube diameter
168 mm
ProtoDUNE: see 3D cad model to identify all positions:
https://edms.cern.ch/document/1543241
Penetrations:
West TPC translation suspension: N. 3, crossing tube diameter
Center TPC translation suspension: N. 3, crossing tube diameter
East TPC translation suspension:
N. 3, crossing tube diameter
200 mm
150 mm
150 mm
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Signal cable chimney FTs:
Spare on Signal cable row FTs:
Laser FTs:
Calibration Fiber CPA FT:
Spare on CPA line FTs:
HV FT:
Manhole:
Cryogenic pipes - roof
N.
N.
N.
N.
N.
N.
N.
8,
2,
4,
1,
2,
1,
2,
crossing
crossing
crossing
crossing
crossing
crossing
crossing
tube
tube
tube
tube
tube
tube
tube
diameter
diameter
diameter
diameter
diameter
diameter
diameter
250
250
100
150
150
156
609
mm
mm
mm
mm
mm
mm
mm
N.
N.
N.
N.
5,
5,
1,
3,
crossing
crossing
crossing
crossing
tube
tube
tube
tube
diameter
diameter
diameter
diameter
304
152
125
250
mm
mm
mm
mm
Cryogenic pipes – north side
N. 1, crossing tube diameter
Angled beam windows – west side N. 3, crossing tube diameter
7
168 mm
300 mm
GTT deliverables for this study
7.1.
7.2.
7.3.
7.4.
7.5.
7.6.
7.7.
7.8.
7.9.
7.10.
7.11.
7.12.
7.13.
7.14.
Insulation and membranes material layout and budgets, including all
fixations and installation mechanisms
A reference to the design codes used and justifying the mechanical integrity
of the setup
An installation procedure
A thermal analysis, justifying the 5W/m2 CERN requirements and defining the
thickness and properties (density, ..) of the insulation
A detailed study of the TCO closure, once the detector installation is over
A detailed study of the installation top cap for the protoDUNE solution
A detailed study of the implementation of the LAr pump penetration
A detailed study of the implementation of the beam pipe penetration for both
cases (WA105 and protoDUNE)
A detailed study of the implementation of the roof penetrations for the
WA105 case
A detailed study of the implementation of the roof penetrations for the
protoDUNE case
A proposal for the implementation of inlets and instrumentation of the
insulation volume
A schedule for the GTT deliverables (from 7.1 to 7.11) to be presented,
while presenting the commercial offer for this engineering study
A cost estimation of the GTT hardware deliverables (from 7.1 to 7.11)
A list of licensees from GTT, capable to execute this project, to be contacted
by CERN for the execution of the project
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8
Summary
With this technical description we lay down the engineering work to be done to define the
cold membrane project.
The timescale is :
1. In the week of the 13th September, submission of a draft of this document to GTT
in order to get an offer for the engineering investigation.
2. Following the offer, we expect to issue a CERN contract for such engineering work
in the week of the 5th October 2015. At that moment all details, which are part of
this document will be frozen.
3. A schedule for the GTT engineering deliverables (from 7.1. to 7.11) should be
presented with the submission of the offer.
4. We expect to have the full engineering study ready for the end of February 2016,
such to be able to prepare the contract for construction up to May 2016.
5. The membrane installation can then start in September 2016, at CERN.