HSEHealth and SafetyFailure Rate and Event Data for use withinRisk Assessments(06/11/17)Introduction1com 3EThe Chemicals,Explosives and Microbiological Hazardous Division 5,CEMHD5,has anestablished set of failure rates that have been in use for several years.This document detailsthose items and their failure rates.For items not within this set,or for which no values arecurrently available the inspector carrying out the assessment should estimate failure rates afterdiscussions with Topic Specialists.The failure rates quoted within this document were derivedand are intended for use on Land Use Planning cases.They were NOT originally intended foruse in COMAH Safety Report Assessment because they do not necessarily take account of allfactors that could be relevant and significant at particular installations.However,in the absenceof site specific data,the values given here may serve as a starting point for safety reports.Figure 1 shows the different types of information that are available in this document.For the fullstructure,see Figure 2.This introductory section also outlines a framework used in CEMHD5 tokeep references pertaining to failure rates and a system for recording the use of non-genericfailure rates used in particular cases.com 3Failure rate and event datacom3EFailure rateEvent dataHuman factorsFREDHFFigure 1 Information covered in Chapter 6KThe first section covers failure rates.CEMHD5 currently has established failure rates or hassome information for most of the items.The items on the diagram in Figure 2 contain a failurerate value(s)and a brief derivation.For rates that have ranges the derivation also contains abrief guide on what factors may affect the valueThe second section(see page 87)contains information on event data.The derivation of therates to be used and how to use them are described.The third section(see page 98)covers human factors.This aim of this section is to help non-human factors specialists determine whether the use of human reliability analysis,andassociated values,is adequate or not.EHSEHS3EHS.3EHS3EHSBEHS.com 3EHS.co3EHS3EHS.com3EHS.com 3BEHomBEHSom 3EH.comHS.com 3EHS.comcom 3EHS.comPage 2 of 102人人U