** serious security threat seen at U.S. nuclear site: U.S. official
** serious security threat seen at U.S. nuclear site: U.S. official
(Reuters) - A bomb-sniffing dog at the Savannah River nuclear site over-reacted when it halted a delivery truck and caused security to put the facility in lockdown, and there does **t appear to be a serious security threat, a U.S. government official said on Monday.
