Nuclear software under scrutiny

A government watchdog will publish a long-awaited report next week on nuclear installations’ vulnerability to computer software problems. The Nuclear Safety Advisory Committee (Nusac) launched its study in the wake of the difficulties experienced at Sizewell B. The plant is unique among Britain’s nuclear power stations in that it relies on software to operate its […]

A government watchdog will publish a long-awaited report next week on nuclear installations’ vulnerability to computer software problems.

The Nuclear Safety Advisory Committee (Nusac) launched its study in the wake of the difficulties experienced at Sizewell B. The plant is unique among Britain’s nuclear power stations in that it relies on software to operate its primary protection system which trips (shuts down) the reactor in an emergency.

Validating new French software initially chosen from Sizewell B proved impossible and Nuclear Electric had to change at a late stage to a tried-and-tested Westinghouse system.

All the UK’s other reactors have hard-wiring linked to sensors as a primary safety system. Sizewell B also has such a system as a back-up.

The bug could not cause a serious nuclear accident because hard-wired shut-down systems operate independently but it could affect control and monitoring systems, security systems and maintenance schedules.

A computer specialist in the Nuclear Installations Inspectorate told a recent EU conference on the millennium bug that the inability to distinguish 2000 from 1900 might cause data-holding systems to eradicate the most recent records because they appeared to be 100 years old.

He said this could lead to maintenance schedules not being adhered to, incorrect calculations on fuel burn-up times and the corruption of dosimetry records.

He cited a number of UK nuclear plants where corrective action was required including a burst fuel-can detection system, a feedwater chemistry monitoring system and a fire-alarm system.