COMAH Human Factors Assessments

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The Control of Major Accident Hazards (COMAH) Regulations 2015

➢Sellafield is a “Lower Tier” COMAH site due to our inventory and categorisation of dangerous substances (either named or classified).

➢COMAH dangerous substances (all non-nuclear) could result in a physical, environmental or health hazard.

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The Control of Major Accident Hazards Regulations 2015

• Regulation 5: General duty to take “all measures necessary” to prevent major accidents and limit their consequences to human health and the environment.

• The resultant of “all measures necessary” equates to “ALARP” , “as low as is reasonably practicable”.

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2.3

COMAH Responsibilities (Lower Tier Establishment)

Lead

ership

(2.1)

Environmental Risk Tolerability

Assessments - ALARP demonstration.

Chemotoxic Assessments/LOPA -

ALARP demonstration.

MAH Assessment Summary

MATTE Assessment Summary

Identify Safety Critical Equipment (CC/CR)

2.6

Emergency Arrangements

2.5

Plant Modifications (PMP)

MAPP

Compliance Status Determination

Provision of information to public

Facility Responsibilities:Central Chemical Safety Team Responsibilities:

Comp

etenc

e (2.2

)

Proce

ss Sa

fety P

erform

ance

Indic

ators

- PSP

I’s (2

.7)

Proce

dures

& In

struc

tions

for S

afe O

perat

ion (2

.4)Co

mplia

nce/

Revie

w &

Audit

(2.7/

2.8)

2.3

Inventory of COMAH Substances

Maintenance/Asset Care

2.4

Human Factors Assessment

2.1

Organisational changes (MOC)

Human Factors Assessment

Emergency Arrangements

Definition of Safety Critical Equipment(HSG 190 Preparing Safety Reports)

Safety Critical:In relation to an item, an item of equipment is safety critical.

if either its failure could cause or contribute substantiallyto a major accident, or its purpose is to prevent, or limitthe effect of, a major accident.

In relation to an event, an event is safety critical if itsoccurrence could lead to a significant release ofcontainment with major consequences.

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COMAH Competent Authority Human Factors Operational Delivery Guide

“where reliance is placed on people as part of those necessary measures, human factors and human reliability should be treated with the same rigour as technical and engineering measures”.

Rigour “the quality of being extremely thorough and careful”.

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Definitions

• Human Factors Walkthrough: The task analysis methodology applied to understand and assess the reliability of the operator / maintenance tasks.

• Human Reliability Assessment: The assessment of human performance taking into consideration factors which can influence it. For example, the characteristics of the task performed, the conditions under which they are performed and the psychological and physical characteristics of the operator.

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Human Factors Walkthrough

The main steps of the walkthrough are as follows:

• The HF specialist in consultation with the operating unit confirms the safety significant tasks.

• The HF specialist becomes familiar with the context of the task, and the plant and process as necessary to adequately perform the walkthrough.

• HF specialist reviews any relevant operating and maintenance instructions and operating experience.

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Human Factors Walkthrough

• Human Factors specialists visit the plant and walkthrough the tasks with relevant operators and maintainers.

• Once the task is understood, the analyst then goes on to understand aspects of the person, task equipment and environment, the “Performance Shaping Factors”

• The error analysis should identify those human errors with significant consequence.

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Human Reliability Guidance

• The qualitative analysis should also consider the impact of performance shaping factors (PSFs); characteristics of the task, equipment, environment and person that affect the likelihood of errors and demonstrate how these support good human performance or make suggestions for improvements where PSFs are considered to have a negative effect.

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Performance Shaping Factors

• Person

• It is really important to understand where human dependency could result in the failure of different safety measures, weakens the defence in depth.

• Task

• Task components

• Instructions

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Performance Shaping Factors

• Equipment

• Human Machine Interface (HMI)

• Alarms

• Indications

• Controls

• Environment - A number of aspects of the physical task environment may impact on human performance

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Human Factors Findings Summary

• Positive Task Characteristics

- Knowledgeable operators and maintainers.

- Good levels of supervision for operational and maintenance tasks.

- Consistent operational control system for bulk deliveries.

- Limited time pressure for task completion in most cases.

- High degree of compliance with configuration control observed.

- Good maintenance planning / scheduling processes giving confidence that maintenance activities will not be missed.

Human Factors Findings Summary • Maintenance Shortfalls

• Procedures:

- Content (missing / incorrect information, typographical errors, poor presentation).

- Use on plant (continuous or reference).

• Training:

- No specific training and competence testing.

- Informal awarding of SQEP status.

• Task specific HF issues:

- Temporary ‘hand written’ labels were observed on a number of the offload valves.

- A number of pressure / thermal relief valves were observed to have poor quality labelling.

- Potential to operate isolation and vent valves out of sequence.

Critical task Competence

• What standard of competence is required to carry out the safety critical task?

• Suitably Qualified and Experienced Person (SQEP).

• Major Accident Hazards (MAH) and Major Accidents to the Environment (MATTE) summaries should be integral to the training programme.

• “Competence” linked to MAH and MATTE scenarios.

• Therefore, aware of the MAH and MATTE potential of the task.

• Aware of the consequences of getting the task wrong.

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Human Performance Tools

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Point of Work Checklist

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COMAH Critical Steps in Operating Instructions

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• Clear indication of the instructions critical steps which

are directly linked to the MAH / MATTE assessments.

• These are similar banners to the nuclear safety case

critical steps for consistency.

Critical Task Audit

• Ideally an audit conducted by an independent.

• Check sheet for auditing critical tasks in line with the documented procedure.

• Comment boxes not tick boxes.

• Time constraints and complexity identified.

• Critical task review and revision if required.

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Conclusions

• Improved the operator and maintainer instructions.

• Use of human performance tools.

• Training programmes enhanced.

• Operator and maintainer competence standards improved for awareness of COMAH-Critical tasks.

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Questions / Comments?

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