* New ABWR reactors are for South Texas plant * NRG stopped investing in the new reactor project * GE-Hitachi also seeking amended ABWR certificate Oct 26 (Reuters) - U.S. nuclear regulators said on Wednesday they would announce on Nov. 1 their decision whether to approve a new version of the Advanced Boiling Water Reactor design proposed by the South Texas nuclear power project. Once the Nuclear Regulatory Commission certifies the amended ABWR design, nuclear developers can use it in proposed reactor projects. The expected affirmation vote comes as the nuclear industry waits for the NRC to certify Westinghouse Electric's amended AP1000 reactor design, which nuclear power operators have started building in Georgia and South Carolina. Westinghouse is majority owned by JaPan's Toshiba . The NRC is expected to certify the amended AP1000 design later this year. Units of U.S. power companies Southern and Scana are building the new AP1000 reactors. NRG Energy , the lead partner in South Texas Project Nuclear Operating Co, which applied for the ABWR amendment, stopped investing in the new reactor project in April 2011, but the NRC has continued with the certification. In 1994, the NRC issued a final design approval for General Electric's ABWR application. The NRC issued the final design certificate for the ABWR in 1997. In 2009, South Texas applied with the NRC to amend the ABWR final design certificate to demonstrate a new ABWR design could meet the commission's new aircraft impact rule following the Sept. 11, 2001 attacks. NRG told the NRC it wanted to build two 1,350-megawatt ABWRs at South Texas in 2006. In 2007, NRG filed an application to build two Toshiba ABWRs at South Texas. Toshiba has built ABWRs in Japan. General Electric and partner Hitachi , which is waiting for NRC to certify their Economic Simplified Boiling Water Reactor (ESBWR) design, also applied with the NRC in late 2010 to extend the original ABWR design certification for another 15 years beyond June 2012, when it expires. That application also includes a design update to reflect NRC requirements for an aircraft impact assessment. BILLIONS The cost of the new reactors at South Texas was originally estimated at $13 billion, which included financing. But in 2009, Toshiba said the cost could be up to $4 billion more than originally estimated. Due in part to the higher cost estimates, San Antonio's CPS Energy, one of the nation's biggest municipal utilities and a partner in the existing South Texas nuclear plant, worked a deal with NRG in 2010 to reduce CPS' stake in the new reactors from 50 percent to 7.625 percent. Also in 2010, Japanese power company Tokyo Electric Power (Tepco) agreed to buy a stake in the new reactors. Tepco agreed to spend about $125 million for a 9.2375 percent stake in the new units and another $30 million for an option to buy an additional $125 million stake in the new units, bringing its total to about 18 percent. But no money changed hands and the deal was never completed because the agreement was conditioned on the United States giving the project a loan guarantee, which has not yet happened. Also, that was before an earthquake and tsunami damaged Tepco's Fukushima Daiichi nuclear plant in Japan in March 2011. Since then, Japan has said it plans to put Tepco under effective state control as a guarantee to compensate people affected by radiation from Fukushima. Energy experts have said Tepco's financial problems will likely force it to pull out of the agreement to buy a stake in the new South Texas reactors. In April 2011, NRG decided to write down its investment in the new reactor project. NRG said it would continue to support its current partners but would not invest additional capital in the effort to develop the project. Toshiba, NRG's minority partner in the project, however has continued to seek certification of the amended ABWR and has so far kept alive the application for a combined operating and construction license to build the South Texas reactors. Toshiba, however, cannot build the new units by itself. The U.S. prohibits foreign control of U.S. nuclear power plants, so Toshiba would need a U.S. partner if it wants to build the reactors.