ML062190444
| ML062190444 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 08/04/2006 |
| From: | Joseph E Pollock Constellation Energy Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML062190444 (3) | |
Text
Calvert Cliffs Nuclear Power Plant Constellation Generation Group, LLC 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 0
Constellation Energy August 4, 2006 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
SUBJECT:
Document Control Desk Calvert Cliffs Nuclear Power Plant Unit Nos. 1 & 2; Docket Nos. 50-317 & 50-318 Special Report: Technical Specification 4.1, Appendix B, Unusual Fish Kill (a)
Calvert Cliffs Nuclear Power Plant, Environmental Protection Plan (Non-Radiological), Technical Specifications, Section 4.1
REFERENCE:
In accordance with Reference (a), Calvert Cliffs Nuclear Power Plant is submitting the following report as described in Attachment (1). This report documents the discovery of moribund or dead cow-nosed rays in the trash racks.
The most probable cause of the death of the rays was low oxygen conditions in the bay. However, it could not be determined whether mortality occurred before or after the rays entered the intake embayment.
Should you have questions regarding this matter, please contact Mr. L. S. Larragoite at (410) 495-4922.
Very truly yours, oseph E. Pollock Plant General Manager JEP/JTJ/bjd
Attachment:
(1)
Unusual Fish Kill Event at Calvert Cliffs Nuclear Power Plant cc:
P. D. Milano, NRC S. J. Collins, NRC Resident Inspector, NRC R. I. McLean, DNR T. Boone, MDE
ATTACHMENT (1)
UNUSUAL FISH KILL EVENT AT CALVERT CLIFFS NUCLEAR POWER PLANT Calvert Cliffs Nuclear Power Plant, Inc.
August 4, 2006
ATTACHMENT (1)
UNUSUAL FISH KILL EVENT AT CALVERT CLIFFS NUCLEAR POWER PLANT On July 11, 2006 Calvert Cliffs Nuclear Power Plant personnel identified a large number of dead fish impinged on the trash racks in the intake. The trash racks were cleaned and approximately 750 - 1000 dead cow-nosed rays, Rhinoptera bonasus, were removed from the intake. This was determined to be a "significant event that indicates or could result in significant environmental impact causally related to station operation" thus was reported to the Nuclear Regulatory Commission (NRC) within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in accordance with Calvert Cliffs Nuclear Power Plant, Environmental Protection Plan (Non-Radiological)
Technical Specifications, Section 4.1.
- 1.
Describe, analyze, and evaluate the event, including extent and magnitude of the impact and plant operating characteristics.
An unusual number of moribund or dead fish on the trash racks in the intake was discovered at approximately 9:30 am on July 11, 2006 during normal operator rounds. There were no dead fish observed floating in the intake embayment area. The plant was operating at full power under normal conditions. The fish kill had no impact on power plant operation. Approximately 750 - 1000 dead cow nosed rays, Rhinoptera bonasus, were removed from the trash racks.
- 2.
Describe the probable cause of the event.
The most probable cause of the death of the rays was low oxygen conditions in the bay.
- 3.
Indicate the action taken to correct the reported event.
The rays were dead when found, no attempts were made to resuscitate. The dead rays were removed from the trash racks.
- 4.
Indicate the corrective action taken to preclude repetition of the event and to prevent similar occurrences involving similar components or systems.
Calvert Cliffs Nuclear Power Plant has previously implemented a number of practices to reduce the potential for fish kills during periods of low ambient dissolved oxygen in Chesapeake Bay bottom waters which are typical during summer. These practices include:
Monitoring of dissolved oxygen levels in the intake.
Removal of two panels in the baffle wall and replacement with 'screens' to allow surface water with higher dissolved oxygen concentration into the embayment area. These screens extend only a short distance (approximately two feet) below the surface of the water, providing a pathway for fish to escape the embayment area.
Operation of installed spray aeration pumps during periods of low dissolved oxygen to create areas of higher oxygen where fish can recover from the effects of the low oxygen.
These actions were in place on July 11*, at the time of the observed fish kill. No additional actions were taken to preclude repetition of the event.
- 5.
Indicate the agencies notified and their preliminary responses.
No other agencies were formally notified. The site's National Pollutant Discharge Elimination System permit, Special Condition N, requires the Maryland Department of the Environment and the Department of Natural Resources to be notified of fish kills only if they are substantial enough to cause modifications to plant operations. As stated above, no change to plant operations resulted from this event.
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