Pedestrians walk past a logo of Toshiba Corp outside an electronics retailer in Tokyo, Japan September 14, 2015. REUTERS/Toru Hanai/File Photo

TOKYO (Reuters) - Japan's Toshiba Corp 6502.T said it will unveil the extent of the writedown on its U.S. nuclear business on Feb. 14 when it reports its results for the quarter ended Dec. 31.

The laptops-to-engineering conglomerate, still recovering from a $1.3 billion accounting scandal two years ago, shocked investors in December by announcing major cost overruns at the U.S. nuclear business it bought in 2015.

“We will explain the reasons why this occurred in the nuclear business and offer measures to prevent a repeat,” Toshiba said on Tuesday in a press release through the Tokyo Stock Exchange.

Last week, media reported the troubled Japanese firm may unveil a writedown of as much as 700 billion yen ($6.18 billion)for its U.S. nuclear business.

To cope with its financial crunch, Toshiba has said it plans to sell part of its core chip business. The firm ranks second after Samsung Electronics 005930.KS in the global market for flash memory chips that are used in smartphones.

Separately, rating agency Standard and Poor’s downgraded Toshiba’s debt to CCC+, or vulnerable to nonpayment, from B- and put the company’s credit watch on negative.