Systems Requirement Document (SRD)

In-Vessel Coils (IVCs)

PBS 15.1

This SRD contains all of the functional, design, safety, operational and
quality requirements for the IVCs.

Table of Contents

[Functions, Basic Configuration and System Boundaries
4](#functions-basic-configuration-and-system-boundaries)

[1.1 System Functions 4](#system-functions)

[1.2 System Basic Configuration 4](#system-basic-configuration)

[1.3 Classification of Systems, Structures and Components (SSCs)
4](#classification-of-systems-structures-and-components-sscs)

[1.4 Design Basis Conditions and Events
4](#design-basis-conditions-and-events)

[1.5 System Boundaries and Interface
5](#system-boundaries-and-interface)

[1.5.1 External Physical Interfaces 5](#external-physical-interfaces)

[1.5.2 External Functional Interfaces
6](#external-functional-interfaces)

[1.5.3 Interfaces Definition Documents
6](#interfaces-definition-documents)

[2 Design Requirements 7](#design-requirements)

[2.1 General requirements 7](#general-requirements)

[2.2 System specific requirements 7](#system-specific-requirements)

[2.3 Structural requirements 8](#structural-requirements)

[2.4 Mechanical requirements (including load conditions)
8](#mechanical-requirements-including-load-conditions)

[2.5 Seismic requirements 8](#seismic-requirements)

[2.6 Fire protection requirements 8](#fire-protection-requirements)

[2.7 Electrical requirements 8](#electrical-requirements)

[2.7.1 Power supply requirements 8](#power-supply-requirements)

[2.8 Earthing and insulation requirements
9](#earthing-and-insulation-requirements)

[2.9 Instrumentation and control requirements
9](#instrumentation-and-control-requirements)

[2.10 Computer hardware and software requirements
9](#computer-hardware-and-software-requirements)

[2.11 HVAC requirements 10](#hvac-requirements)

[2.12 Vacuum requirements and vacuum classifications
10](#vacuum-requirements-and-vacuum-classifications)

[2.13 Thermal management requirements
10](#thermal-management-requirements)

[2.14 Electromagnetic requirements 10](#electromagnetic-requirements)

[2.15 Nuclear shielding requirements
10](#nuclear-shielding-requirements)

[2.16 Chemical requirements 10](#chemical-requirements)

[2.17 Materials requirements 10](#materials-requirements)

[2.18 Manufacturing requirements 10](#manufacturing-requirements)

[2.19 Assembly requirements 10](#assembly-requirements)

[2.20 Installation requirements 11](#installation-requirements)

[2.21 Testing and inspection requirements
11](#testing-and-inspection-requirements)

[2.22 Decommissioning requirements 11](#decommissioning-requirements)

[2.23 Other services 11](#other-services)

[3 Safety Requirements 11](#safety-requirements)

[3.1 Safety design criteria 11](#safety-design-criteria)

[3.2 Safety limits 11](#safety-limits)

[3.3 Monitoring requirements 11](#monitoring-requirements)

[3.4 Safety-specific instrumentation
12](#safety-specific-instrumentation)

[3.5 Safety related testing and inspection
12](#safety-related-testing-and-inspection)

[3.6 Qualification requirements 12](#qualification-requirements)

[3.7 Safety related operations and procedures
12](#safety-related-operations-and-procedures)

[3.8 Occupational safety 12](#occupational-safety)

[3.9 Environmental impact requirements
12](#environmental-impact-requirements)

[3.10 Safety system reliability requirements
12](#safety-system-reliability-requirements)

[3.11 Other safety requirements 12](#other-safety-requirements)

[4 Operation and Maintenance 12](#operation-and-maintenance)

[4.1 Operation 12](#operation)

[4.1.1 System operation states 12](#system-operation-states)

[4.1.2 Operational conditions 12](#operational-conditions)

[4.1.3 Central control room: equipment, technical and procedure
documents
13](#central-control-room-equipment-technical-and-procedure-documents)

[4.2 Maintenance 13](#maintenance)

[4.2.1 Maintenance plan 13](#maintenance-plan)

[4.2.2 Remote handling 13](#remote-handling)

[4.2.3 Hot cell and waste management requirements
13](#hot-cell-and-waste-management-requirements)

[4.3 RAMI 13](#rami)

[4.3.1 Requirements: Reliability, accessibility, maintainability,
inspectability
13](#requirements-reliability-accessibility-maintainability-inspectability)

[4.3.2 Risk reducing design actions and compensating provisions
13](#risk-reducing-design-actions-and-compensating-provisions)

[5 Quality Requirements 14](#quality-requirements)

[5.1 Quality Classification 14](#quality-classification)

[6 Applicable Codes and Standards 14](#applicable-codes-and-standards)

# Functions, Basic Configuration and System Boundaries {#functions-basic-configuration-and-system-boundaries .unnumbered}

## System Functions

The in-vessel coils (IVCs) provide control of:

-   Edge Localized Modes (ELMs);

-   moderately unstable Resistive Wall Modes (RWMs);

-   plasma Vertical Stability (VS);

## System Basic Configuration {#system-basic-configuration .Style-Heading-22h22Level-+-Left:--1.02-cm-Before:--0-pt-After:...}

The IVCs consist of 27 picture frame-type coils which provide ELM and
RWM control and (2) toroidal ring coils (in nine 40 degree segments for
each of the vacuum vessel segments) which provide vertical stabilization
(VS) control. All are of vacuum jacketed, water cooled copper design.
The coils and feeders are located behind the shield modules. The upper
feeders are routed out of the vacuum vessel through the upper shield
ports; the lower feeders are routed out of the vessel through 9
inter-period feed throughs. The coils are located in the vacuum vessel
as follows:

-   [picture frame coils]{.underline}-one upper, one mid, one lower in
    each of the 9 vacuum vessel segments; and

```{=html}
<!-- -->
```
-   [ring coils]{.underline}-one upper and one lower 40 degree segment
    in each of the 9 vacuum vessel segments.

## Classification of Systems, Structures and Components (SSCs)

The IVC elements and feeders are considered as non-Safety Important
Components (non-SIC), and there is no safety credit function associated
with them.

The IVC elements and feeders are considered as non-Nuclear components
(non-ESPN).

The IVC elements and feeders are considered as "Pressure Equipment"
components and shall be in compliance with the Pressure Equipment
Directive (PED).

## Design Basis Conditions and Events

The design basis conditions include the four defined ITER operating
scenarios in addition to the disruption events listed below:

With all ELM/RWM coils shorted; VS in saddle configuration:

-   Major disruption with 36ms linear decay

-   Major disruption with 16 ms exponential decay

-   VDE fast downward with 36 ms linear decay

-   VDE fast downward with 16 ms exponential decay

-   VDE fast upward with 36 ms linear decay

-   VDE fast upward with 16 ms exponential decay

With only the upper VS shorted:

-   Major disruption with 36 ms linear decay

-   VDE fast upward with 36 ms linear decay

With only the lower VS shorted:

-   Major disruption with 36ms linear decay

-   VDE fast downward with 36 ms linear decay

The design basis events for the IVCs and feeders include the following:

> • Installation / removal of the coils by remote handling (RH)
> equipment.
>
> • Self weight of the coils.
>
> • Pressure due to coolant.
>
> • Magnet operation through their full specified current and voltage
> range for control of ELM events, resistive wall modes, and vertical
> stabilization.
>
> • Mechanical interface loads (due to temperature differentials, etc.).

## System Boundaries and Interface

The IVCs and feeders are part of the vacuum vessel Project Breakdown
Structure (PBS); the vacuum vessel is located in the bore of the
toroidal field coils. The IVCs are attached to the vacuum vessel wall.
They are located in cavities within the blanket shield modules. The
feeders for the IVCs are similarly located in cavities within the
blankets. Upper feeders are routed out of the vacuum vessel through the
upper shield ports; lower feeders are routed out of the vessel through 9
inter-period ports. The feeders extend from the cryostat, where they
connect to bus work (or cable) from the IVC power supplies and coolant
lines from the IVC coolant system.

### External Physical Interfaces 

The interface with the vacuum vessel shall be the ELM-VS supporting
system in the vacuum vessel. Gravity, EM, and thermally- induced loads
are reacted by these support systems.

The interface to the blankets shall be at the cavities in the blankets
which create the space in which the IVCs and feeders reside.

The interface to the vacuum vessel lateral upper ports shall be the
routing of the upper feeders through them.

The interface to the triangular support in the vacuum vessel shall be
the routing of the lower feeders through the double shell and up through
the triangular supports in the vessel.

The interface to the IVC power supplies shall be at the cryostat exit
points of the feeders where they connect to the room temperature bus or
cable from the IVC power supplies

The interface to the IVC cooling system shall be at the cryostat exit
points of the feeders where they connect to piping from the IVC cooling
system.

The interface to the instrumentation monitoring system shall be at the
cryostat exit points of the feeders where instrumentation lines located
in the feeders are attached to lines from the instrumentation monitoring
equipment.

The assembly and maintenance requirements of the IVCs shall result in
interfaces with the remote handling system.

### External Functional Interfaces

IVC operational EM loads, fault EM loads, gravity loads, thermally
induced loads, and seismic loads shall be reacted by the vacuum vessel
walls.

IVC feeders shall be supported by attachments to the vessel walls.

The blanket modules shall provide electromagnetic shielding for the IVCs
from rapid plasma electromagnetic events.

The IVC coils shall support the blanket cooling manifolds.

The blanket modules shall provide nuclear shielding for the IVCs as
defined in Section 2.15.

The vacuum vessel shall provide a vacuum environment for the coils as
defined in Section 2.12.

The magnets shall have a maximum outgassing and leak rate as defined in
Section 2.12.

### Interfaces Definition Documents

The following interface definition documents shall be provided to the
following external systems:

> • IVC-VV
>
> • IVC-power supplies
>
> • IVC- instrumentation
>
> • IVC-Central Interlock System
>
> • IVC-assembly
>
> • IVC-inspection, repair and replacement
>
> • IVC-cryostat

-   IVC-Safety

-   IVC-blanket / shield

-   IVC-Remote Handling

-   IVC-feeders

-   IVC-diagnostics

> • Feeders- port plugs

-   Feeders (upper) -- VV port plug extensions

-   Feeders (lower) -- vv pass throughs

> • Feeders-cooling system
>
> • Feeders-power supplies
>
> • Feeders-cryostat
>
> • Feeders inspection, repair and replacement

# Design Requirements

## General requirements

The IVCs shall be designed in accordance with ITER Magnet Structural
Design Criteria, sections 1 to 3. The IVC documentation will contain
analysis to demonstrate that all the criteria are satisfied.

## System specific requirements

To ensure vertical stability of the plasma, the parameter, ∆Z~max~/a,
has been identified as a figure of merit for characterizing the
effectiveness of the vertical stabilization, where ∆Z~max~ is the
maximum "sudden" plasma displacement, which can be stabilized. In
present devices, ∆Z~max~/a \> 0.05 is required for reliable vertical
stabilization with robust stability achieved with ∆Z~max~/a \> 0.1. The
current and voltage for the VS coils will satisfy the requirement that
∆Z~max~/a \> 0.05 and approaching ∆Z~max~/a = 0.1 so that it can control
the plasma vertical position with minimal overshoot.

The DIII-D data, in combination with the results from the other devices
and theoretical considerations, provide four guidelines toward the
requirements for ELM suppression coils on ITER: 1) the coils should be
as close as possible to the plasma to maximize the edge perturbation
while minimizing the core perturbation, 2) the coil rows should be on
the outboard side but not solely on the outboard midplane, 3) the
perturbation should be as pitch aligned with the unperturbed equilibrium
field lines as possible, and 4) the width of the edge region having good
overlap of magnetic islands calculated with the vacuum fields from the
coils should be greater than a threshold value. Good overlap of magnetic
islands can be characterized by a Chirikov parameter (magnetic island
width / island spacing) being greater than 1.0. The maximum ELM size in
the DIII-D experiments at q~95~ \~ 3.6 is correlated with the width of
the edge region (.85 \< ψ~N~ \<1) having Chirikov parameter \> 1. The
threshold value for the ELM suppression range from these experiments was
used to guide the requirements for the currents in the ITER coil design.
These guidelines have been used to set the coil current requirements.
The application of a resonant magnetic perturbation in the edge can
create striations of particle and heat deposition on the divertor
plates. To distribute the heat and particle, the currents in the ELM
control coil windings will have the capability to be varied at 2-4 Hz.

The in-vessel coils for ELM control can also be used for resistive wall
mode (RWM) control. Comparison of the performance of the coil
configurations using the VALEN-3D code modeling with a single-mode model
shows superior performance when all three toroidal rows of coils are
used (stabilized β~N~ = 3.74) compared with mid-plane coils (stabilized
β~N~ = 3.39). The use of just the top and bottom coils enables
stabilized β~N~ = 3.83. The required current for RWM control appears to
be modest compared with the ELM control requirements; however, further
analysis is ongoing. This is not expected to alter the current
requirements for the in-vessel ELM control coils since the conditions
when RWM stabilization is predicted to be important occur at reduced
plasma current, Further work is being done to determine the current and
voltage requirements for RWM stabilization.

## Structural requirements

The structural design criteria are defined in [Magnet Structural Design
Criteria](https://user.iter.org/?uid=2F4KZ3)
([ITER_D_2FMHHS](https://user.iter.org/?uid=2FMHHS),
[ITER_D_2ES43V](https://user.iter.org/?uid=2ES43V),
[ITER_D_2FKTTG](https://user.iter.org/?uid=2FKTTG),
[ITER_D_2FDCA3](https://user.iter.org/?uid=2FDCA3) ).

## Mechanical requirements (including load conditions)

Refer to Sect. 1.4.

## Seismic requirements

The IVCs shall withstand the seismic loads on the magnets as defined in
the [ITER Load Specifications](https://user.iter.org/?uid=222QGL_v3_1)
(part of the Project Background Documents), and those that are
transmitted from any components supported on them (for example, the
blanket/shield cooling manifolds).

## Fire protection requirements

None.

## Electrical requirements

The coil insulation shall withstand the normal operating voltages as
well as the off-normal voltages produced by a single insulation fault
anywhere in the coil electrical circuits.

The coil insulation shall withstand fault voltages from the power supply
system that are defined as being within the design basis.

Current-carrying parts outside the coils, such as coil terminals and
feeders, shall include redundant barriers, to limit the impact and to
provide redundancy in the event of a short-circuit.

All insulation surfaces, including bus-bars, cooling lines,
instrumentation wires and penetrations that are exposed to the torus
vacuum shall be at ground potential.

The coil insulation shall be designed to meet the test requirements of
Sect. 2.21.

### Power supply requirements 

Each of the 27 ELM/RWM coils shall be fed by an individual power supply;
the two VS coils shall be interleaved with (2) power supplies (to reduce
voltage to ground). The power supply requirements are given in Table
2.7.1

.

**Table 2.7.1 Power Supply Requirements**

  ----------------------- ------------- -------------- --------------- ----------------------
  **ELM coil power supply                                              
  requirements (3 turns /                                              
  coil; 1 power supply                                                 
  per coil)**                                                          

                          Supply        Power supply                   Voltage response time
                          current, kA   voltage, kV                    (ms)

  for ELM control only    20 (peak)     0.13                           10

  For moderately unstable 2 (peak)      0.10                           \<1
  RWM control                                                          

  For ELM control plus    20 (peak)     0.13                           \<1
  moderately unstable RWM                                              
  control                                                              

                                                                       

  **VS coil power supply                                               
  requirements [(2 power                                               
  supplies interleaved                                                 
  with the (2) 3-turn VS                                               
  coils)]{.mark}**                                                     

                          Supply        Power supply   Pulse rate      
                          current, kA   voltage, kV                    

  For a single large      80 (peak)     [1.8]{.mark}   Max. of (10)    
  disturbance                                          0.3 s pulses;   
                                                       min. 10 s       
                                                       between two     
                                                       disturbances.   

  For repetitive          20 (peak)     [1.8]{.mark}   Max. of (100) 1 
  disturbances                                         s pulses; min.  
                                                       time between    
                                                       disturbances 2  
                                                       s.              

  For noise in dZ/dt      10 (RMS)      [1.8]{.mark}   Continuous      
  diagnostics                                                          
  ----------------------- ------------- -------------- --------------- ----------------------

{Ref: "Status report on STAC 4 action: Development of power supply
concept for in-vessel coil system "' IDM No. ITER_D-2FKBMH V1.0, dated
25/09/2008.) Note: the highlighted values did not come from the STAC
report, and need to be discussed.

There shall be no single point failure of the power supplies that result
in damage to the IVCs

## Earthing and insulation requirements

All magnet and feeder casings shall be grounded to the vacuum vessel by
their mounting bolts.

## Instrumentation and control requirements

(Instrumentation and control requirements for the IVCs need to be
developed - **TBD**).

## Computer hardware and software requirements

IVC computer hardware and software shall follow ITER standards described
in Plant Control Design Handbook (PCDH).

## HVAC requirements

Not applicable.

## Vacuum requirements and vacuum classifications

The vessel coils shall be designed and constructed in accordance with
the requirements specified in the ITER Vacuum Design Handbook (VDH).

The maximum total allowable helium test leak rate shall be **TBD**
Pam^3^/s. This is consistent with achieving the global leak and
outgassing rate requirements for the vacuum vessel of TBD Pam^3^/s.
Vacuum conditions and classifications are defined in the [Vacuum
Handbook](https://user.iter.org/?uid=2EZ9UM), once approved.

## Thermal management requirements

All IVCs and feeders shall be cooled by water with single phase flow.
The coil feeders supply both power and coolant to the coils.

## Electromagnetic requirements 

None.

## Nuclear shielding requirements

None

## Chemical requirements

The external surfaces of the cases of the IVCs and feeders shall
designed, handled and cleaned in accordance with and be in compliance
with the VDH.

## Materials requirements

Materials used in the construction of the in.-vessel coils and feeders
shall have well-characterized mechanical and structural properties and
be listed in the ITER Materials Properties Handbook (hereinafter
referred to as the MPH).

Materials not listed in the MPH shall be required to undergo a
qualification process defined in **TBD**.\]

## Manufacturing requirements

Not applicable (N/A)

## Assembly requirements

The IVCs shall be sized to enter the vessel through the horizontal
ports.

The IVCs shall be able to be assembled, repaired and replaced using the
IVC RH equipment. (per RH document).

## Installation requirements

Tolerance on current centers of the windings at all locations shall be
+/- 2 cm.

Installation requirements shall relate to accuracy of installation,
component weights and clearances for crane lifts and remote handling
equipment. These shall be defined in the assembly interface documents
and drawings of the IVCs and feeders. The interfaces to buildings are
listed in 1.5.1.

## Testing and inspection requirements

For each magnet manufacturing contract, a QA programme, including an
Implementation Plan and adequate quality control and acceptance
procedures, shall be established in accordance with the ITER QA manual.

Electrical tests shall be performed in accordance with Sect. II-2.5
"Electrical Testing" of the Magnet Superconducting and Electrical Design
Criteria (N 11 MA 2 R 0.1).

## Decommissioning requirements

The IVCs shall be composed of materials that can be cleared for
recycling after 100 years

## Other services

None.

# Safety Requirements

## Safety design criteria

Under any normal, upset, emergency, or fault condition, no combination
of loads shall lead to damage to SIC components, including: vacuum
vessel confinement barrier, primary cooling system lines for the vacuum
vessel and IVC components, fuelling system lines, or cryostat
confinement barriers that could result in release of radioactivity
exceeding the specified limits.

## Safety limits

Not applicable (N/A)

## Monitoring requirements

Not applicable (N/A)

## Safety-specific instrumentation

None

## Safety related testing and inspection

Not applicable (N/A)

## Qualification requirements

Not applicable (N/A)

## Safety related operations and procedures

None

## Occupational safety

Not applicable (N/A)

## Environmental impact requirements

None

## Safety system reliability requirements

None

## Other safety requirements

None

# Operation and Maintenance

## Operation

### System operation states

TBD

### Operational conditions

The IVCs shall be designed to operate in the ambient vacuum conditions
of the VV with the VV at a normal operating temperature of 100° C. and
with a matching inlet water temperature of 100° C. The IVCs shall also
be designed to withstand bakeout in the ambient vacuum conditions of the
VV with the vacuum vessel at a bakeout temperature of 200° C

### Central control room: equipment, technical and procedure documents

Not applicable (N/A)

.

## Maintenance

### Maintenance plan

Need to detect, isolate, and recover from any failures of the IVCs and
their feeders.

Maintenance plans shall be developed which includes monitoring and
testing of bolted joint resistances and detection of leaks in the coil
and feeder casings.

### Remote handling

#### Maintenance class

The maintenance class of all IVC coil system components shall be Class
3.

#### Maintenance frequency and duration

The IVCs shall not require any regular maintenance.

#### Environment conditions during maintenance

See Section 4.1 (Operation).

### Hot cell and waste management requirements

Not applicable.

## RAMI

### Requirements: Reliability, accessibility, maintainability, inspectability

**TBD** spare coils and feeders shall be provided for the IVCs.

Because visual inspection is impossible during operation, and is also
very limited outside of operation, regular testing of all insulation
shall be considered as a means to detect the early stages of insulation
degradation.

### Risk reducing design actions and compensating provisions

The IVCs shall be provided with bolted links between sections to permit
removal and replacement of failed sections.

#### Repair or replacement of IVCs or feeders

Repair or replacement of IVCs or feeders shall require the use remote
handling equipment and specially designed tooling. The remote handling
systems shall assist personnel when background radiation is low enough
to permit "hands on" involvement; fully remote operation shall be
required when background radiation levels prohibit this. The first step
in any repair or replacement operation will be the removal of the
blanket shield modules in the affected area. In-place repairs after
activation will be extremely limited to operations such as servicing of
the bolted current links, repair of case leaks, or re-torquing of
attachment bolts. Major degradation of insulation resistance or failures
shall require replacement of the affected section(s).

# Quality Requirements

## Quality Classification

The IVC components (coils, structures and feeders) are defined as ITER
quality class 1, according to the document [MQP Quality
Classification](https://user.iter.org/?uid=22F4TT_v2_0). [(need to
check)]{.mark}

# Applicable Codes and Standards

See Section 2.1 and individual Procurement Arrangements.