UPDATE 1-Western Refining's Yorktown ops normal after flaring

* Sour water stripper unit problem causes flaring

* No impact on production

(Update with company comment)

NEW YORK, July 12 (Reuters) - Western Refining (WNR.N) said on Monday production at its 64,500 barrel-per-day refinery in Yorktown, Virginia was not affected by a problem that had caused flaring on Saturday.

In the filing to regulators on Saturday, Western said ammonium hydroxide, nitric oxide and sulfur dioxide were released due to a problem with the sour water stripper, but added that the quantities might not be above reportable levels.

"As a pre-emptive measure, we filed the report until we knew what the emissions were going to be," said Gary Hanson, a spokesman for the company.

Hanson said the incident did not impact production and operations continue on plan. (Reporting by Janet McGurty and Ratul Ray Chaudhuri Editing by Marguerita Choy) (janet.mcgurty@thomsonreuters.com; Reuters Messaging: janet.mcgurty.reuters.com@reuters.net; 646 226 3027))