* Manufacturer's report showed safety modifications were
* Report says rejection contributed to reactors' shutdown
* Mitsubishi Heavy says design decisions followed accepted
By Nichola Groom
LOS ANGELES, Feb 6 The owner of a shuttered
Southern California nuclear power plant was aware of problems
with its new steam generators before they were installed, two
lawmakers said on Wednesday, citing a report by the maker of the
In a letter to U.S. Nuclear Regulatory Commission Chairman
Allison Macfarlane, Senator Barbara Boxer and Representative
Edward Markey said a 2012 document by Mitsubishi Heavy
Industries Ltd, maker of the San Onofre power plant's
steam generators, found that some safety modifications were
rejected by both Mitsubishi Heavy Industries and plant owner
Southern California Edison due to "unacceptable consequences."
The potential changes may have raised the possibility that
the plant would need to seek a license amendment because of
changes to the steam generators' design, the lawmakers said the
"SCE is fully cooperating with the NRC review process and is
complying with all requests for information and documents
related to the company's San Onofre Nuclear Generating Station,"
Southern California Edison spokeswoman Jennifer Manfre said in
an emailed statement. "SCE leadership takes very seriously all
allegations raised by the letter."
In the letter, the lawmakers said the report also showed
that Edison's and Mitsubishi's decision to reject those
modifications contributed to problems with the faulty steam
generators and the shutdown of two nuclear reactors at the San
Onofre nuclear power plant.
"This newly obtained information concerns us greatly," Boxer
and Markey wrote in the letter.
The report is confidential and Reuters was not able to
"All design decisions for the steam generators were made in
accordance with well-established and accepted industry standards
and practices, along with our own and third-party operating data
and experience," Mitsubishi Heavy Industries said in a statement
issued to Reuters.
Both reactors at the 2,150-megawatt San Onofre plant have
been shut down for more than a year due to tube wear problems in
the units' new steam generators. Mitsubishi Heavy built the
generators and installed them in 2010 and 2011.
The Japanese company said it has been cooperating with the
utility and the NRC in investigations since the shutdown of the
The NRC is reviewing Southern California Edison's plan to
restart one of those units. Southern California Edison is a unit
of Edison International.
"We have received the letter from Senator Boxer and
Congressman Markey and will respond in the normal course of
business," NRC spokesman Victor Dricks said in an email. "As an
independent safety agency, we will review all available
information in making a judgment as to whether the plant would
meet our safety standards if restart were permitted."
San Onofre sits on the California coast halfway between Los
Angeles and San Diego. It is the largest power plant in Southern