Three nuclear power reactors, one in New Jersey and the other two in New York, remained shut down amid worries over any possible hurricane-inflicted damage to their transmission networks as well as their cooling systems, but authorities said there were no risks to the public.

The National Hurricane Center said Sandy had weakened early Tuesday as it moved inland. And the encouraging news is that The New York Stock Exchange will reopen Wednesday for regular trading after being shut down for two days.

The superstorm has not caused severe injuries to big companies such as chemical makers BASF and DuPont. The former reported that its East Coast facilities had incurred minor damage, while the latter, many of which are not in the direct path of Sandy, has reopened its two facilities, one in Connecticut and one in Massachusetts.

U.S. President Barack Obama on Tuesday declared "a major disaster" in the states of New Jersey and New York, ordering federal aid to supplement state and local recovery from Sandy.

Obama and his Republican rival Mitt Romney canceled a second day of campaign events to focus on Sandy's victims.

Photo taken on Oct. 29 ,2012 shows a tree has fallend down after Hurricane Sandy's passage through New York City. [Sina.com]