(CNN) -- The Nuclear Regulatory Commission on Friday ordered U.S. nuclear power plants to begin implementing safety recommendations made in an effort to prevent a crisis from occurring as it did in Japan after last year's devastating earthquake and tsunami.
Among the recommendations, plants must install improvements to protect safety equipment and devices to monitor water levels in spent fuel pools. A third order applies only to plants with boiling-water reactors that have so-called Mark I or Mark II containment structures.
Mark I containment housing is the same design that was used at Japan's Fukushima Daiichi nuclear power plant, where three reactors melted down after the station was struck by the tsunami that followed Japan's historic earthquake in March 2011. The disaster resulted in the widespread release of radioactive contamination that forced more than 100,000 people from their homes.
The disaster occurred when a 15-meter (49-foot) tsunami inundated the coastal plant, knocking out the cooling systems for the three operating reactors and their associated spent fuel pools, causing the reactors to overheat and hydrogen gas explosions that blew apart the building housing reactors No. 1 and 3. Another hydrogen blast is believed to have damaged the inside of the No. 2 reactor, while engineers were struggling to manage an estimated 100,000 tons of highly contaminated water that was used to cool the reactors during the emergency.
"These reactors must improve venting systems that help prevent or mitigate core damage in the event of a serious accident," the NRC said in a news release announcing the orders for U.S. plants.
In addition to the changes in safety procedures, the NRC is also seeking information from every operating U.S. nuclear power plant regarding risks caused by earthquakes and flooding and the plants' emergency procedures in the event of prolonged power loss.
The plants have until the end of 2016 to fully comply with the safety orders, according to the NRC.