Press Release-III-07-002, NRC Finds Problem with Tank Design of Low to Moderate Safety Significance

Press Release-III-07-002: NRC Finds Problem with Tank Design of Low to Moderate Safety Significance

ML070430033
Person / Time
Site:	Clinton
Issue date:	02/12/2007
From:	Office of Public Affairs Region II
To:
Category:Press Release
References
Press Release-III-07-002
Download: ML070430033 (2)

Text

NRC NEWS U.S. NUCLEAR REGULATORY COMMISSION 2443 Warrenville Road Lisle IL 60532 Web Site: http://www.nrc.gov E-mail: opa3@nrc.gov No. III-07-002 February 12, 2007 CONTACT: Viktoria Mitlyng (630) 829-9662 NRC FINDS PROBLEM WITH TANK DESIGN OF LOW TO MODERATE SAFETY SIGNIFICANCE The Nuclear Regulatory Commission staff has issued its final determination that the calculation method used by Clinton Nuclear Power Station to ensure proper functioning of a pump needed in certain accident conditions was inadequate. The NRC determined the issue to be of low to moderate safety significance. The plant is operated by Exelon Generation Co.

The calculation problem had to do with the minimum level of water in the reactor core isolation cooling water storage tank to ensure continued operation of the high pressure core spray pump.

The high pressure core spray pump draws water from the tank to cool the reactor when the regular source of cooling water becomes unavailable in certain accident conditions.

A 2006 NRC inspection concluded that the mistake in calculations would result in rendering the pump unavailable to perform its safety function in certain accident conditions. The low water level in the tank would lead to entraining air into the pump suction line and preventing the pump from functioning properly.

The utility has taken corrective actions to address the problem.

James Caldwell, NRC Regional Administrator, said: Even though regular plant operations were not affected by this issue and the plant continued to be safe, the NRCs finding shows how important it is to thoroughly review the design calculations for safety-significant equipment.

The NRC uses color-coded inspection findings and performance indicators to assess nuclear plant performance. The colors start with green and then increase to white, yellow or red, commensurate with the safety significance of the issues involved.

White findings normally result in additional NRC inspections and meetings with the utility.

Based on the white finding, the NRC issued a Notice of Violation to Exelon Generation Co. for its failure to ensure the adequacy of design of the high pressure core spray system. The company is required to respond to the Notice of Violation within 30 days, describing its corrective actions and steps it is taking to prevent a recurrence of the violation.

The letter notifying Exelon of the white finding will be available from the NRCs Region III Office of Public Affairs or in the NRCs online document library at:

http://www.nrc.gov/reading-rm/adams/web-based.html .