MICE Safety System

DE Baynham

TW Bradshaw

MJD Courthold

Y Ivanyushenkov

Scope

• MICE hazards and solutions

• Hydrogen control and safety system

• MICE safety system

MICE Layout

MICE Phase I initial

MICE Phase I final

MICE Hazards

Beam

Radiation

FireExplosionOverpressureMaterial brittlenessSkin burn Radiation

HV=>Sparks

HV

RF RFLH2Tracker LH2 LH2 TrackerParticledetectors

High magnetic field =>High mechanical forcesMagnetic stray field

Photo detectorsand front-end

electronics

Optical fibres

Photo detectorsand front-end

electronics

Optical fibres

HV

TOF

Beam

Radiation

RF RFLH2Tracker LH2 LH2 Tracker

Radiation

Particledetectors

Radiation safety is achieved by: - shielding the beam line; - no access to the experimental hall when RF power is on; - local shielding of some bits of cryogenics equipment such as control electronics, cold boxes and valve boxes; - local shielding of detectors front-end electronics

MICE Hazards: Solutions

Beam RF RFLH2Tracker LH2 LH2 Tracker

Particledetectors

High magnetic field =>High mechanical forces

Magnetic field safety is achieved by: - passive magnetic shielding of both the MICE control room and the ISIS linac (brings magnetic field down to below 5 gauss-level in the public areas outside the experimental hall); - restricted access to the experimental hall.

High mechanical forces on the MICE components are:- being analysed and understood ;- taken into the account in the MICE design.

MICE Hazards: Solutions (2)

Beam RF RFLH2Tracker LH2 LH2 Tracker

FireExplosionOverpressureMaterial brittlenessSkin burn

RadiationHV=>Sparks

HV

Particledetectors

Hydrogen safety is achieved by:• careful design of the hydrogen absorber : - FEA analysis of the windows (confirmed by tests); - avoiding cold surfaces where air might be plated; - a double barrier between hydrogen and air.• careful design of the hydrogen system: - a closed system concept keeps hydrogen venting at the minimum; - hydrogen is stored as a solid compound in a hydride bed; - passive pressure relief system is implemented; - hydrogen zone is localised; - ignition sources are kept outside hydrogen zone.• certification of all materials• tests of sub-assemblies and assemblies• test of complete system

MICE Hazards: Solutions (3)

Instrumentation

Pressuregauge

Non-returnvalve

-P P VP Vacuum pumpBursting diskPressure

relief valveValvePressure

P

Chiller/Heater Unit

Helium supply

Hydrogen supply

P

Nitrogen supply

PP

1 m3

P

-P P VP Vacuum pumpBursting diskPressure

relief valveValvePressure

regulator

Coolant

Out

(20m3 capacity)

Metal Hydride storage unit

(20m3 capacity)

P

PP

VP02

VP01

Heater /Chiller

1 bar diff

PP

PP

Helium supply

Hydrogen supply

Extract hood

P

Nitrogen supply

PP

PP

1 m3

Vent manifold

PG01

RV06

PV01

PV18

PV03

PV05

PV07

PG03PPG02

PV20Test absorber module

In

Absorbervolume

0.5 bar diff

0.9 bar diff

PV19CV04

CV17RV10

BD09

HV08

0.5 bar diff RV13

0.9 bar diff BD12

HV11

PV14

High level ventNon return valve 0.1 bar RV21

Buffervessel

PV15

PP

PV02

Argon jacket

TTS3

T

T

TS1

Temperaturesensor

H2

H2

H2

Control logic – Fill SequenceChiller on

Set TS1_sp = TS1_initialPV2,3,5,7,14,17,18,19

closedCV4 closedPV1 open

VP2 on, PV20 open

Cooling System onSet TS2_sp = 15K

Start Pressure Control LoopStart Vac Monitor

Open PV2,3Open CV4

TS1<TS1_spAnd

VG3<1mbar

PG1PG1_sp

Close PV2&3 and CV4Stop Pressure Control Loop

Set TS1_sp = TS1_lowOpen PV5

LS1 > LS1_sp

H2 System Ready

Increment/DecrementTS1

EmptySequence

VG3<1mbar

Vac monitor

Pressure Control

Yes

No

Yes

No Yes

No

Note: ***_sp - set point

Empty Sequence

Open PV7Close PV2,3,4Set TS1_sp =

TS1_lowSet TS2_sp = 20K

Stop cryocoolerStart Absorber Heater Control Loop

LS1<LS1_low

EmptySequence

Yes

No

Close PV1

PG2<0.1barAND

TS3>100K

H2 System Empty

Yes

No

1bar<PG2<1.3bar

Increment/DecrementTS3

Absorber Heater Control

Yes

No

Stop Absorber Heater Control Loop

TS3>30K

Yes

No

Helium Purge Sequence

VP1 OnClose

PV1,14,17,18,19Open PV2,3,5,7

Open CV4 100%

Close PV19Open PV18

Open CV4 5% to control flow

VG5<1mbar

H2 System Purged

PurgeSequence

No

Open PV19

Yes

1bar<PG1<1.3barAND

1bar<PG2<1.3bar

Close PV19Open PV18

Open CV4 5% to control flow

VG5<1mbarNo

Close PV18, Open PV19, Open CV4 100%

Yes

1bar<PG1<1.3barAND

1bar<PG2<1.3bar

Close PV19Open PV18

Open CV4 5% to control flow

VG5<1mbarNo

Close PV18, Open PV19, Open CV4 100%

Yes

1bar<PG1<1.1barAND

1bar<PG2<1.1bar

YesYesYes

No No No

Close PV18

MICE DAQ and Control System

Interfaces

Hydrogen system

MICE Safety system

Hardwired status signals: ready (for use) / not ready, fault, H2 leak, H2 being vented

PSI Solenoid

Linde Fridge

Fridge Ready (and in use)

Fridge Ready

Solenoid Powered

Solenoid Quenched Solenoid Current Ramping

3 Signals from solenoid

Fire alarm, power cut