CLAS 12 TORUS MAGNET VENDOR COST ASSESSMENT

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CLAS 12 TORUS MAGNETVENDOR COST ASSESSMENT
Ref. No. BI2 7/2b-2007 4/24/2007
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ITEP, Moscow, RFO. Pogorelko, I. VetlitskyThe
Efremov Institute, St-Petersburg, RF V.Belyakov,
Deputy Director of the Efremov InstituteA.Turikov
, Director of EFO Plant of the Efremov
InstituteS.Egorov, V.Korsunsky,, V.Bondarenko
Contributors
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Contents

• Introduction
• Present status of TORUS design
• Basis to evaluate manpower
• Cost estimate worksheets
• Summary

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1. Introduction

• This report supplements Technical Design Report
  (Ref. No. BI2 7-2007) prepared by the
  ITEP/Efremov collaborative team under supervision
  of the staff of Jefferson Laboratory (JL) on the
  torus magnet of New Hall B CLAS 12 Spectrometer
  system for the Jefferson Lab 12 Gev Upgrade
  project.
• The report contains
• brief description of torus conceptual design
  (section 2)
• preliminary cost estimate of the work proposed to
  be done by ITEP/Efremov team on torus
  construction (sections 3 and 4).
• Resulting cost estimate template is given in the
  Summary (section 5).

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2. Present status of Torus design
Initial basic requirements

• Six flat trapezoidal coils mounted on common cold
  support core (the cold hub)
• Warm opening of 75 mm in diameter around the beam
  axis
• Outer width of a coil cryostat at the front face
  not more than 95 mm
• Polar angle coverage inside coils as seen from
  nominal target point Q 5-40 degrees
• The magnetic field produced by TORUS must
  satisfy the following conditions

• The torus will be installed in the underground
  hall. Existing access to the hall is through the
  tunnel with the cross-section dimensions of
  3m4.5m.
• The envisaged design option implies
• factory manufacturing of the coils and
  prefabricated parts of the cold structure and
  cryostat, which dimensions allow transportation
  through the tunnel
• assembly of the torus magnet and cryostat
  (including welding) inside the underground hall.

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Reference conductor is de-keystoned SSC
superconducting cable, which operating current is
established to be 3150A at 4.6T
2. Present status of Torus design (continued)
SSC key-stoned superconducting cable
Reference design option of the conductor
Experimental sample of de-keystoned SSC cable
TORUS operating points

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2. Present status of Torus design (continued)

• In the result one configuration has been selected
  as the reference design option

Several version of configuration of the coils
have been analyses
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Parameters of reference design option
2. Present status of Torus design (continued)
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Magnetic field calculation has been performed
for the reference design option. Complete set of
field components ( Br , Bz, Bf ) or ( Bx, By, Bz
) are available in the electronic form. An
example below is refered to the following
notation
2. Present status of Torus design (continued)
Rztg? x-Rsin? yRcos?
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2. Present status of Torus design (continued)
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2. Present status of Torus design (continued)

• Coils and cases
• Each of 6 superconducting coils consists of the
  following components
• Winding Pack (Pos. 1) containing two pancake
  layers of turns, wound with the conductor which
  is covered with turn insulation. Each layer
  contains 140 turns. In the reference design
  option the layers are integrated in one double
  pancake containing 280 turns, which furnished
  with two electrical terminals and featured with
  2.32 km continues length of conductor. In the
  spare option the layers form two separate
  windings (140-turn single pancakes) which are
  furnished with their own electrical terminals and
  featured with the continues length of conductor,
  reduced down to 1.16 km. Final selection of the
  design option will be made on the proceeding
  stages of the project.
• Conducting sheets (Pos. 2) made of Al with high
  electrical and thermal conductivities. The
  conducting sheets furnished with the cooling
  pipes serve as the heat drains and as the
  eddy-current heaters for the quench-back
  protection of the coils.
• Outer fiberglasses wrap (Pos. 3) enveloping the
  winding pack and conducting sheets. It serves to
  reduce mechanical stress at the edges of the
  winding pack, which is originated from the
  difference in thermal contraction of the winding
  and the case, and also to fill the gap between
  the winding pack and the case.
• Al alloy case (Pos. 4) bearing electromagnetic
  and gravity loads acting to a coil.
• Mechanical and thermal integrity of a coil is
  provided by its vacuum pressure impregnation with
  epoxy

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Cold-mass assembly unitCold structure of the
torus consists of the coils cases, common cold
central support cone (cold hub) and outer
supporting ring all made of Al alloy and bearing
all the electromagnetic and gravity forces acting
to the superconducting (SC) coils. Cold structure
and SC coils form cold-mass assembly unit.
2. Present status of Torus design (continued)
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Transportable prefabricated parts of this unit
are assumed to be assembled together in the
underground hall. All the parts of this unit are
furnished with cooling pipes for cryostating at
helium temperature and 80 K thermal shields
(which are not shown in the sketches). Cryogenic
communications and intercoil SC jumpers
(bus-bars) run along outer supporting ring. Been
assembled the cold-mass assembly unit is hang in
the cryostat onto four fiberglass hangers
connected with the brackets to the outer
supporting ring.
2. Present status of Torus design (continued)
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2. Present status of Torus design (continued)

• Cryostat and supports
• The above cold-mass assembly unit is housed in
  welded stainless steel cryostat. The cryostat
  provides thermal isolation of the cold-mass
  assembly unit and also transmits the gravity of
  this unit to the base through the in-cryostat
  hangers, outer beams, vacuum shells, warm outer
  supporting ring and the legs. The cryostat has
  the ports providing access to the intercoil
  electrical joints and cryogenic piping.
• Two options of the cryostat have been proposed
  option B and option E. The last was selected as
  the reference design option.
• In the both options the prefabricated parts of
  the cryostat are assumed to be transported into
  the underground hall through the tunnel and
  welded together around the cold-mass assembly
  unit.

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2. Present status of Torus design (continued)
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2. Present status of Torus design (continued)
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Plane panels of the V-shaped chicks have welded
intermediate supports (rods)
2. Present status of Torus design (continued)
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2. Present status of Torus design (continued)
CLAS 12 Assembly sequence
Frame beam
spider
Welded seam
Installation of a segment of the cold ring
Installation of the upper spider
Installation of the first beam of the cryostat
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Sequential installation of cryostat beams and
cells
Installation of the supports
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2. Present status of Torus design (continued)
CLAS 12 Assembly sequence
Installation of segments inside cryostat cells
Segment of rear external ring
In-cryostat hanger
Central vacuum tube
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Stress Analysis Analytical and numerical models
have been used to optimize and verify the design
suggestion of- winding pack composition -
coils in the cases- cold assembly unit (coils,
supporting cold ring, cold central core)-
cryostatWinding pack compositionLocal
numerical code has been used to calculate
equivalent (smeared) properties of the winding
pack as a periodical composite consisting of
superconducting cable, turn insulation, Cu strip
and insulation separating plate, depending or an
option. The separating plate has been added to
the winding to improve thermal contraction
compatibility of the winding and Al-alloy case.
The equivalent property are used in the
proceeding global analysis.
2. Present status of Torus design (continued)

• Copper strip improves thermal contraction
  compatibility of the winding and Al-alloy case.
• The separating plate improves thermal contraction
  compatibility of the winding and
• Al-alloy case.

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ANSIS code has been used to perform 3-D stress
analysis of the coils and simplified Beam-Shell
model of the whole cold mass assembly unite.
2. Present status of Torus design (continued)
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2. Present status of Torus design (continued)

• The developed stresses are quit acceptable for
  all considered loads.
• Maximum out of plane displacement, caused by dead
  weight and EM loads, is of about 4 mm.

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3-D model of the hub consist of 60 degree
sector of the hub with the slot for the nose
part of the coil case
2. Present status of Torus design (continued)

• Maximum radial displacement of the case nose is
  about 0.6 mm. The maximum stress intensity in the
  Hub is 94 MPa, with membrane and bending stresses
  being lower.
• The calculated stresses are quite acceptable for
  Al-alloys used in cryogenic applications.

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ANSIS models were used to optimize the supports
located between the panels of cryostat, loaded by
atmospheric pressure. The pitch for 12X18H10T
steel is 360 mm, deflection is 1.65mm. It is
recommended to consider reinforcement of the
plane panels by a set of ribs.
2. Present status of Torus design (continued)
The Option E Cryostat is less loaded by the
atmospheric pressure in comparison with Option B
because of smaller vacuum volume. The most loaded
support element of its structure is the Support
Ring located in the section of the center of
mass. This Ring is loaded by the Dead Weight of
the magnet ( 48 kN) and of the cryostat ( 180
kN). A simplified FE model of the Support Ring
has been developed and analyzed to get a
conservative estimation of stresses in the
Ring. The weights of magnet and cryostat are
applied to the Ring in corresponding points of
attachments. The total load is 114 kN for a half
of the Ring. The ring has a tube cross-section
with the diameter of 200 mm and the wall
thickness of 10 mm. The material of the Ring is
stainless steel. The maximum stress intensity in
the Ring is 73 MPa, that is acceptable for
ordinary stainless steel with Yield Stress of
about 200 MPa. Preliminary stress analysis has
shown that mechanical stresses developed in the
Torus magnet structure and the Cryostat are
within allowable values. Optimization of the
structures and more detailed structural analysis
will be carried out at the next stage.
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Thermal AnalysisHeat loads on cryogenic system,
evaluated preliminary are
2. Present status of Torus design (continued)
Forced flow supercritical 4.4 K and 80 K He
cooling schematic is assumed preliminary for the
torus magnet. Liquid Helium (LHe) and Liquid
Nitrogen (LN2) vessels are connected with the
torus by the vacuum isolated lines (VIL) running
through one or two ports of the cryostat onto the
cold ring. All the valves are assumed to be
selected according to the US standards and
supplied by the American firms.
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2. Present status of Torus design (continued)
Torus cryogenic schematic 4.4K Forced flow
supercritical He line
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2. Present status of Torus design (continued)
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Torus cryogenic schematic 80K Forced flow He
line
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Thermal analysis for steady state operation of
the coils have been performed with ANSYS under
the mass flow rates of He in the cooling tubes
between 2.5 g/sec (DT 0.3K) and 12 g/sec (Dp
0.15 MPa)
2. Present status of Torus design (continued)
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2. Present status of Torus design (continued)
Inductive-resistive bridges of QDS. L1 - L6
superconducting coils LC1 - LC6- compensation
normal conducting coils
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2. Present status of Torus design (continued)
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Simplified network of the quench-back protection
schematic
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Preliminary simulations have been performed with
simplified models for 25 combinations of
operating current, magnetic field and parameters
of QDS
2. Present status of Torus design (continued)
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3. Basis to evaluate manpower
Manpower norms are established on the basis of
analogues works carried-out during last 10 years
(participation in the ITER reactor design and
analysis, ITER Model Coil Programme, 12MJ 1m bore
NbTi Charging Coil for MIT (USA) LDX experimental
plasma facility) and presently on-going projects
(normal conducting tokamak for Kazakhstan,
preparation for manufacturing of a NbTi poloidal
Coil of Superconducting Magnet System of ITER
reactor).
The ITER reactor
Assembly of normal conducting tokamak machine for
Kazakhstan
The Toroidal Field Coil Insert produced and
tested at 40kA 13T as a part of ITER Model Coil
Programme
9m diameter 250 tons weigh NbTi PF1 coil to be
produced in Russia
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3. Basis to evaluate manpower (continued)
Labor unit cost is re-calculated (rubles per
man-month ? /h) from the norms which are
presently in force at STC Sintez and pilot
plant EFO of the Efremov Institute
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4. Cost template worksheets (continued)
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4. Cost template worksheets (continued)
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4. Cost template worksheets (continued)
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4. Cost template worksheets (continued)
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4. Cost template worksheets (continued)
Note () Total cost of Item 4 includes 240 000
for VacuumCryogenic accessories and Quench
Protection system, W/o the last total cost of
manufacturing prefabricated parts of cryostat
constitutes 1148298
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5. SUMMARY