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Assessing the safety of the beam energy tracking system (BETS)

David Jonesdavid.huw.jones@cern.ch

Content

1. BETS, and its role in the LBDS2. Assessing the safety of BETS

What may happen if something goes wrong

Hole in Copper

450GeV p+ beam

Verena Kain

Q5R

Q4R

Q4L

Q5L

Beam 2

Beam 1

Beam Dump Block

Septum magnet deflecting the extracted beam H-V kicker

for painting the beam

about 700 m

about 500 m

Fast kicker magnet

MOPLT034, J.Uythoven et al.

Q5R

Q4R

Q4L

Q5L

Beam 2

Beam 1

Beam Dump Block

Septum magnet deflecting the extracted beam H-V kicker

for painting the beam

about 700 m

about 500 m

Fast kicker magnet

MOPLT034, J.Uythoven et al.

LHC Beam Dumping System (LBDS)

BEI System

Interlocking

MKD, MKBSystems

BEA and BEM1 Systems

Data acquisition and Energy reference generation

BIC System

Dump request management

Dump command

Dump Request

Dump Request

Dump Request

LHC DIPOLES

4/5 and 7/8

BEA and BEM2 Systems

Data acquisition and Energy reference generation

LHC DIPOLES

5/6 and 6/7

MSDSystem

LBDS

Assessing safety

Function description of system – Correct operation

Function description of subsystems

System function

Sub-System function

Sub-System function

Sub-System function

Sub-System function

Sub-System function

Sub-System function

Sub-System function

Sub-System function

Sub-System function

Sub-System function

Sub-System function

System function

Sub-System function

Sub-System function

Assessing the safety of BETS

Power Converter

DCCT

Dipole Magnets

DCCT

Reference voltage, +10V

Reference voltage, 0V

MPX ADC Averaging TX

Optical FibreTo BEM card

TX

Serial RXDecoder

In1 * Imax /Iref

In2 * Imax /Iref

In3 * Imax /Iref

In4 * Imax /Iref

Voter

0.3% tolerance

Voter

0.3% tolerance

Conversion

LUT

ANYBUS

VMEBUS

Optical FibreFrom a BEA card

8bit BUSTo the PLC controllersof the MKD and MKB

magnets

32bit BUSTo the BEI card

Serial RXDecoder

Optical FibreFrom a BEA card

RXa

RXb

Dump Request Dump Request

Dump Request Dump Request

Averaging

Symbol Failure mode Effect 1st Coverage 2nd Coverage

RX, Receiving

RX1 Invalid format (CRC) F1 BEM BEI

RX2 No data, 1ms timeout F1 BEM BEI

RX3 Incorrect measurement of an analogue channel F1 BEM BEI

RX5 Incorrect value of ib calculated3 F1 BEI None

RX6 No value calculated (internal timeout) F1 BEM BEI

RX7 No value calculated (no timeout) F1 BEI None

RX, Interlocking

RXD1 Incorrect detection of invalid received data F1 BEM None

RXD2 No detection, rx interlock failure F2(coverage)4 Diagnostics None

Voter, Interlocking

IT1 Incorrect detection of anomalous current F1 BEM None

IT2 No detection, interlock failure F2(coverage)4 Diagnostics None

Averaging

AV2 Incorrect result F1 BEI None

AV3 No value calculated (internal timeout) F1 BEM None

AV4 No value calculated (no timeout) F1 BEI None

Conversion, Calculating an energy reference value

ER1 Incorrect result F1 BEM None

ER2 No value calculated (internal timeout) F1 BEM None

ER3 No value calculated (no timeout) F1 BEI None

Assessing the safety of BETS

X1

X2

X3

X4

Assessing the safety of BETS

X0

X1

X2

X3

AVAILABLE

AVAILABLENo Surveillance

FAILED SAFE

FAILED SILENT

Internal Dump Request

Common-mode failure across all ofthe BEA cards, resulting in an

undetected failure

Common-mode failure across all ofthe BEM surveillance mechanisms

on both cards- watchdog timer, CRC check etc

Common-mode failure of part of theBEM functionality, on both cards

X0

X1

X2

X3

Conclusions

•The BETS system is a safety critical component of the LHC

•Progress is being made towards assessing how safe it is

Questions ?