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Personnel Protection System (PPS) – Definition

• Interlock system, to protect personnel from Ionising Radiation

(and other hazards)– (Note: does not include equipment protection)

• Intended to satisfy the requirements of –

– [UK] Ionising Radiation Regulations 1999 (IRR99)

– IEC 61508 (?)“Functional Safety of Electrical / Electronic / Programmable-Electronic Safety-Related Systems” –>

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• Assisted search system, to clear personnel from (shielded) areas

• Door locks, to keep area clear of personnel

• Door switches, to make area safe on entry

• Warnings – audible and visual

(– People!)

(– People!)

• Permit / Prevent operation of equipment, to control the hazard(s)

– via “Permits to Operate” (PPS outputs) –>

PPS – What it does

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PPS Design Criteria (for Accelerators)

• Very low probability of ‘fail to danger’

• Use ‘failsafe’ techniques

– implies safety is achieved by switching things off –>

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The Daresbury Laboratory Personnel Safety (PS) System (1 of 2)

• Used on: SRS, ESRF, Diamond, ERLP, ISIS (from 2007)

• Relay-based, modular, logic system

• ‘Dual Guardline’ System– duplicated inputs, logic, & outputs– both circuits must agree it’s safe to operate ( 2oo2 system)

• ‘Failsafe’ techniques– Current flow = safe– Relay logic (relays mostly fail open circuit)– Inputs from ‘Positive break’ safety switches –>

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– Disable equipment by two independent means

– Disable equipment in a failsafe manner

– Disable via hardware, not software (but safety-PLC ok?) –>

The Daresbury Laboratory Personnel Safety (PS) System (2 of 2)

• Provides audible and visible warnings (IRR99: ‘failsafe’?)– Search tone

– Internal illuminating ‘Danger’ signs

– Internal blue lighting

– External illuminating signs

• Annual check to ensure that both guardlines are fully functional

• PS ‘Permits’ – principles for controlling equipment:

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MICE PPS

• Search Areas

– MICE Decay Solenoid Area

– MICE Hall

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MICE Hall

Decay Solenoid Area

(shielding: schematical representation only)

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MICE PPS – Controlled equipment

• ISIS Synchrotron Beam (to enable: Decay Solenoid Area vacated)– via ISIS PPS (hooks already included)

• MICE RF System (to enable: MICE Hall vacated)– switch off RF drive to IOTs– switch off HT to IOTs

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• Superconducting Magnets – sequence to enable

1) MICE Hall searched (but ‘Limited Access’ permitted)

2) Hall inspection for loose magnetic material – not PS function

3) Insert and turn ‘Magnet Enable’ key

Dropping search does not disable magnet PSU, – turn off key does

– Interface to magnet PSU t.b.d.

• Other systems … ? (over to you)

MICE PPS – Controlled equipment, contd.