Nuclear regulators delay decision to require radiation filters

HOUSTON, March 19 (Reuters) - The U.S. Nuclear Regulatory Commission (NRC) on Tuesday voted to delay a decision to order operators of more than two dozen older nuclear plants to install filtered vents as part of the agency's post-Fukushima safety upgrades, according to an NRC memo posted on its website.

The commission's memo also enhances a March 2012 order requiring "hardened" venting systems at 31 boiling-water reactors with Mark I and Mark II containments.

But the action falls short of calling for operators to install filters able to retain radioactive material during severe accidents. The NRC memo also lays out a rule-making process to further study the issue.

In January, the NRC staff recommended that filters be installed.

The venting changes are in response to lessons learned from the 2011 Fukushima nuclear disaster in Japan.