1 Site Description Report Cooper Nuclear Station 1200 Prospect Road Brownville, NE 68 321 March 2 , 2009 1.0 Background and Objectives The Environmental Protection Agency (EPA) is in the process of developing 316(b) cooling water intake structure requirements that reflect the best technology available (BTA) for minimizing adverse environmental impact for all existing power plants and manufacturing facilities. As part of this process, EPA staff is visiting electric generators and manufacturers to b etter understand the cooling water intake structure (CWI S) technologies in use at ty pical facilities, including the site

- specific characteristics of each facility and how these affect the selection and performance of CWIS technologies. EPA is also visitin g facilities to better understand cooling water use and specific issues or technologies that can affect 316(b) compliance. As part of its site visit to the Nebraska City Station , EPA also collected information on Nebraska Public Power District’s ( N PPD) Co oper Nuclear Station (Cooper)

. 1 2.0 Facility Description Cooper is located about 3 miles south of the town of Brownville in eastern Nebraska on a 1300 acre site . The facilit y operates under NPDES permit NE0001244 ; the permit expired June 30 , 2006

. 3.0 Electricity Generation and Transmission Cooper is a nuclear generating station with one reactor capable of generating 800 MW. 4.0 Cooling Water System and Intake Structure Cooper withdraws once

- through cooling water from a CWI S on the shoreline of the Missouri River. The facility ’s design intake flow (DIF) is 964 million gallons per day (mgd) and the average actual intake flow (AIF) is 747 mgd. Water passes through a trash rack and then into 9 intake bay s; each intake bay has a dual flow coarse mesh ( 3/8”) traveling screen and each pair of bay s feeds a circulating water pump with a capacity of 229 mgd (or 159,000 gallons per minute [gpm] each). One bay feeds the service water pumps, which have a total

1 NPPD is a different branch of the state electricity generation agency than Omaha Public Pow er District (OPPD) but operates in concert w ith OPPD.2 capacity of 43.2 mgd (or 30,000 gpm). The design through

- screen velocit y ranges from 1.7 to 2 feet per second (fps). To better handle debris and sediment loading, the facility has taken several steps in the past . See Section 7.0 for more information. 5.0 Impingement and Entrainment Information Facilit y r epresentatives noted that impingement counts at Cooper are very low and that man y of the collected organisms were shad. They also stated that many of the pre

- approved impingement approaches in the 2004 Phase II rule were unappealing. For example, the 0.5 fps threshold is likely infeasible on large rivers and barrier nets would likely be destroy ed b y debris. Entrainment has not been studied in any

detail. 6.0 Cooling Tower Feasibility Facilit y representatives noted that they have explored converting to clos e - cy cle cooling; the cost was estimated to be $400 million, largel y due to nuclear safet y procedures. They

did not identify

an y insurmountable technical hurdles. Water consumption was also raised as a potential problem. 7.0 Debris Handling Cooper installed a sloping weir wall in the earl y 1970s to better control sediment loading at its CWI S. 2 The design was based on river flows t ypical of time and was reviewed b y the Army Corps of Engineers and the I owa Institute of Hy draulics . The wall begins on the upstream side of the screenhouse and extends slightly above the water’s surface. The wall gradually becomes shorter as it extends downstream; this design was expected to shield the CWI S from excessive sedimentation by

channeling suspended sediment bey ond the CWI S. In the past, s edimentation caused pump shutdowns from clogging and requires mechanical excavation every

6 months (usually

by divers). 3 Sediment has also significantly increased the maintenance required for the travelin g screens, increased the frequency of backwash cy cles, and has restricted intake flow piping. Facility representatives noted that Fort Calhoun is considering installing a similar wall. The facility

also added turning vanes along the river bottom to steer flow (and sediment) away

from the CWI S. Sonar sensors were also added in the screenwells to measure the amount of sedimentation.

2 The w eir w all also diverts some ice in the winter. 3 Sonar sensors in the screenwells detect sediment levels . Backwash cycles (using divers) lead to a reduction in generation (derating), as well as additional concerns over thermal discharges due to the lower volume of cooling water being w ithdrawn.3 Cooper also has problems with debris loading. Debris carry over from the traveling screens clogs the condenser tubes, requiring frequent cleaning. Facility representatives noted that the condenser must be backwashed on approximately a weekl y basis, requiring a temporary shutdown. 4 Some debris remains and must be manuall y cleaned out during the next regularly scheduled o utage. In the past 2 years, Cooper has replaced its single

- entry traveling screens with dual

- flow screens to reduce the debris carry over. This conversion cost approximately

$6 million. By

the time the installation was completed, maintenance was required on the first set of screens that were installed. Despite the changes, condenser backwash and sediment removal r emain as operational challenges, although problems are now less frequent. Ice has been a historic problem at Cooper as well. Ice floes in the river often break into smaller parts that can clog the open area of the screens, leading to as much as a 5 foot differential across the screens. Cooper installed an ice deflector in the river to divert surfac e level ice away from the CWI S. 8.0 Repowering/Fu ture Uses EPA did not collect any

information about repowering at this site. 9.0 Cooling Ponds There are no cooling ponds onsite. 10.0 Ownership N PPD is a public utility

that is owned b y the state of Nebraska. The entire state is supplied by

public power. 11.0 3 16(a) EPA did not collect any

information about thermal discharges at this site. 12.0 Ash Handling Cooper does not use coal as a fuel and therefore has no ash ponds. 13.0 Air Emissions Controls EPA did not collect any

information about air controls at this site.

4 Facility representatives noted that 3220 MWhrs w ere lost in 2 002 due to 45 condenser backwash cycles.4

14.0 Additional Information Cooper had intended to comply with the 2004 rule by

installing modified Ristroph screens with a low pressure spray and separate fish return. Facilit y representatives noted that they had considered a sedimentation pond at th e CWI S, but were concerned about the ability to maintain a consistent flow, the need for constant dredging, and the ability of such a sy stem to adapt to the large changes in river level. Facilit y representatives stated that, at another facility (Gerald Ge ntleman, located on an inland lake) the state fish and game agency has expressed an interest in maintaining once

- through cooling, as there are too many shad in the waterbody and the cooling water withdrawals are helpful in culling the population of less de sirable fish. Additionally , the canals feeding the lake are completely drained every 5 y ears per Federal Energy Regulatory

Commission (FERC) requirements, killing an y remaining fish or invertebrates.

Attachments Attachment A PowerPoint Presentation (March 2, 2009)5

Attachment A

— PowerPoint Presentation (March 2, 2009) Please see DCN 10

- 6522A accompany ing this document.