High Integrity/High-Integrity Component 

HI/HICHigh Integrity/High-Integrity Component is a structural integrity classification given in the UK to components in a nuclear reactor, where the consequences of a postulated gross failure are unacceptable and where it is not reasonably practicable to provide physical defence in depth. In these cases, a safety case has to be produced, which includes additional measures over and above recognised nuclear design and construction code requirements.

Guidance on the production of such a safety case is provided by the UK Technical Advisory Group on the Structural Integrity of High Integrity Plant (TAGSI). It is based on a multi-legged approach to provide conceptual defence in depth, covering aspects such as: design and manufacture; functional testing; failure analysis; and forewarning of failure. The performance of NDT applied to HICs needs to demonstrate the ability to detect, characterise and size, with high confidence, defects of the qualified examination defect size (QEDS) (see ‘What the Hec?!’, April 2017) through the inspection qualification process.

For more information on HI/HIC see: www.onr.org.uk/new-reactors/uk-hpr1000/reports/ukhpr1000-step2-ar-18-018.pdf

What the hec?! articles are not intended to be the definitive account on the topic or acronym in question. Readers’ comments and contributions are welcomed. Email: ndtnews@bindt.org