What is it?

It is a nuclear site licence condition (LC 14) for licensees to implement adequate arrangements for the production and assessment of safety cases justifying safety during all phases of the installation lifecycle i.e., during design, construction, manufacture, commissioning, operation, and decommissioning.


Safety cases are therefore living documentation, that can consist of a single submission or several hundred documents, and which must be maintained throughout the lifetime of the installation. Once implemented, they must be regularly reviewed and updated to take account of plant modifications, operating experience gained, changes to standards, guidance or regulatory expectation, or learning from experience (LfE).


A key component of the evidence to substantiate the safety case will be claims made on human activity at the installation. Of primary importance are any claims made on operator intervention to control the installation integrity.


HBSC analysis can be a major component of the analysis work required to support the safety case development and approval.

Why is it important?

HBSCs are categorised (as Types A, B or C) by the consequence of potential errors:


  • Type A: latent errors resulting in the unavailability of a claimed safeguard.
  • Type B: Errors that result in the initiation of a fault scenario.
  • Type C: Errors that result in a failure to complete a post fault operator action.

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What do we do?

Our team will support analysis of the fault schedules and help identify those faults that require substantiation.
Our Human Factors specialists will agree the HBSC method to be applied including qualitative and quantitative approaches. The analysis approach taken will vary depending on HBSC Type. Typical activities include:


  • Qualitative analysis including identification of Performance Shaping Factors using established Task Analysis methodologies.
  • Quantify the Human Error Probabilities (HEPs) using the agreed method (e.g. Accident Sequence Evaluation Programme (ASEP) or Technique for Error Rate Prediction (THERP) or the Standardised Plant Analysis Risk Human Reliability Assessment (SPAR-H).
  • Deliver a verified HBSC substantiation report.

Our Human Factors team will work closely with Probabilistic Safety Assessment and Safety Case teams to provide a fully integrated service. These can be client based teams or our in-house teams.

Our Experience

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Our team members have completed numerous HBSC projects. Our experience includes:


  • New Build facilities
  • Supporting the Generic Design Assessment (GDA) submissions for ABWR, UK HPR1000,  AP1000
  • Expert support to the regulator

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