BNI/BONI meaning

BNI/BONI describes, in nuclear construction and EPC contracting, the balance of the nuclear island: all plant, systems and structures within the nuclear island boundary other than the Nuclear Steam Supply System (nsss). It is an industry term, not defined in legislation or case law, but widely used in contracts, schedules and interface matrices to allocate scope, price and risk. Typically included are containment and other civil structures, auxiliary and safety systems, I&C to the extent not forming part of the NSSS, electrical distribution within the island, HVAC, radiation monitoring, radioactive waste handling, lifting and fuel-handling equipment, and the related installation, commissioning and testing. The term is distinct from Balance of Plant (BOP) and from the conventional island (e.g. turbine-generator). In legal practice it is used to identify the responsibilities of the BONI/BNI contractor versus the NSSS supplier, including design authority, safety classification and codes, quality assurance, programme, performance guarantees, acceptance criteria, warranties and indemnities, and regulatory interfaces. Usage is broadly consistent across England & Wales, Scotland and Northern Ireland (with oversight in Great Britain by the Office for Nuclear Regulation). In Ireland the expression may appear in cross-border supply contracts, notwithstanding the absence of nuclear power stations.