GEISMAR, La. (AP) — A Houston-based chemical company contends that it should not be penalized for a March plant fire at its vinyl chloride complex in Geismar because an unexpected and unprecedented chemical chain reaction touched off the blaze.

The Westlake Chemical Corp. recently released details about the March 22 incident in a 14-page letter to environmental regulators, according to the Advocate (http://bit.ly/MdVDbw ). In the letter, Andrew Kenner, vice president of Westlake’s manufacturing division, says the reaction was not the result of operator error and could not have been anticipated.