1 / 8

CRITICALITY INCIDENT DETECTION GEOFF DRUCE

CRITICALITY INCIDENT DETECTION GEOFF DRUCE. CRITICALITY INCIDENT DETECTION. Aims & Objectives to provide the IRMF community with an overview of criticality incident detection & alarm systems

diep
Download Presentation

CRITICALITY INCIDENT DETECTION GEOFF DRUCE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CRITICALITY INCIDENT DETECTION GEOFF DRUCE

  2. CRITICALITY INCIDENT DETECTION Aims & Objectives • to provide the IRMF community with an overview of criticality incident detection & alarm systems • to discuss the requirement to assign the system with a ‘safety status’ (Nuclear Site Licence Condition) • to describe the importance of criticality incident detection & alarm system testing to demonstrate that the demands of the safety status can be achieved • to gain IRMF community acceptance of the UK CIDS Service Providers produced Good Practice Guide into the NPL suite of documents

  3. CRITICALITY INCIDENT DETECTION What is criticality? • An unintentional or accidental occurrence of nuclear fission • When and where can it occur? • When all engineering controls and procedures fail • In an Aqueous process • In a Metal process What measures do we take should failure occur? • Rapid detection of the fission [criticality] • Personnel evacuation to a safe haven [primary function] • Warn of re-entry to the incident area • Option to make a process ‘safe’ • Remote assessment of radiological conditions • Emergency Planning

  4. CRITICALITY INCIDENT DETECTION Rapid detection of the criticality incident • From Delafield & Clifton (SRD R 309 1984) • Minimum credible event 1 E14 fissions • Tissue dose in free air @ 1 metre from an unshielded event/assembly • Hydrogen Moderated Event • 2 E-16 Gy/fission for Gamma • 1 E-16 Gy/fission for Neutron • Unmoderated Metal Event • 0.5 E-16 Gy/fission for Gamma • 3 E-16 Gy/fission for Neutron

  5. CRITICALITY INCIDENT DETECTION Detectors • Geiger Counters • Ion Chambers • Scintillation • Junction Diodes Trigger Methods • Dose Rate • Integrated Dose • Rate of Change

  6. CRITICALITY INCIDENT DETECTION Criticality Incident Detection & Alarm System • Detection System • Audible Alarm - Primary Alarm • Instantly recognised tone • Time to alarm criteria of 200 E-3 S • Human Factors • Visual warning in high ambient noise areas >80 dB • Visual Warnings - Secondary System • Remote outputs • Facility Control Room • Emergency Site Control Centre • Process Interface • Process Shutdown Systems

  7. CRITICALITY INCIDENT DETECTION Safety Status • Safety Assessment Principles for Nuclear Plant • Specific requirements for criticality • Availability & Reliability requirements • Failure to Alarm on Demand • Safety Integrity Levels • Consideration of post incident information • Assigning the Safety Status* • Detection & Alarm System • Detection & Alarm System with positive process action • The detection & alarm system will not prevent criticality

  8. CRITICALITY INCIDENT DETECTION Reliability & Testing • Dual Redundancy • Single point of failure criteria • Type Testing • To demonstrate fitness for purpose • Periodic Testing • To demonstrate the degree of certainty to function correctly Good Practice Guide for the UK • Why? • Agree common approach • Who was involved? • Part of the NPL portfolio

More Related