US firm ValvTechnologies (VTI) has been selected to zero leakage valves to the Tennessee Valley Authority Watts Bar 1 & 2 nuclear power plants.

The order forms as part of a Post-Fukushima upgrade programme or FLEX initiative, which calls for diverse and flexible coping capabilities to address the loss of cooling capability and electrical power at US nuclear power plants resulting from a severe natural event.

In a statement, Bill Henwood, Vice President for Nuclear Power at ValvTechnologies described the contract as a "significant assignment."

"Our Zero Leakage valve solutions were judged on their own merits and not compared to existing linear or quarter turn technology," he said.

Watts Bar 1, which entered operation in 1996, was the latest commercial nuclear power plant to come online in the USA. Watts Bar 2, still under construction, is expected to come online in December 2015.