Fears huge nuclear dump buried under concrete dome could be unleashed into the sea

The Runit Dome was built to contain radioactive waste from nuclear experiments in the middle of the 20th century (Picture: US Defense Special Weapons Agency/Cover Media)

A Pacific Island is sitting atop a nuclear time bomb that could pollute the oceans for centuries.

Scientists have discovered that a concrete structure built to contain radioactive waste from Cold War-era testing is showing signs of deterioration.

The site, known as Runit Dome, sits on Runit Island in the Enewetak atoll in the Marshall Islands.