Nuclear power plants improve performance.

U.S. Nuclear Power Plants Top 75% Capacity

News about record-breaking performances by U.S. nuclear power plants is beginning to sound like, well, a broken record. The latest achievement: America's 109 units set a reliability record for the fifth straight year, compiling a 75.1 percent capacity factor. That's up from 72.5 percent in 1993, according to the Utility Data Institute. _Twenty years ago_, the industry's capacity factor stood at 57.2 percent.

The record breaking figure goes even higher if the four units that were out of service in 1994- Browns Ferry 1 and 3, Fermi 2 and Indian Point 3- are excluded. Without them, the industry turned in a whopping 77.9 percent capacity factor. (Capcity factor is the percentage of electricity produced compared with a palnt's maximum potential output.)

Leading the way last year: Union Electric Co.'s Callaway plant, with a 102.4 percent capacity factor. (Callaway exceeded the 100 percent mark by operating every day of the year and generating slightly more electricity than its 1,150 megawatt power rating, thanks to improved thermal efficiency.)

Prairie Island 2, operated by Northern States Power Co., finsihed a close second with a 101.5 percent capacity factor.

In all, 29 units topped the 90 percent mark- up dramatically from 16 in 1993. Forty had capacity factors of at least 85 percent. And 55 units- more than half of America's nuclear power fleet- exceeded 80 percent. The statistical median for all U.S. plants last year was 80.4 percent, meaning that a few poor performers pulled down the average capacity factor. (Sixty-nine of the 109 units topped the national average.)

Much of the credit for the industry's soaring capcity factor goes to the utilities' success in reducing the length of outages-either scheduled outages for refueling and maintenance or unplanned ones. The median length for refueling outages fell in 1994 from 55 days, down from 64 days in 1993. Refueling outages hit a high of 83 days in 1989 and have been dropping ever since.

Of the 51 units that refueled last year, 10 had refueling outages of 40 days or less- "unheard of in this country," says Stephen Floyd, director of nuclear economics at the Nuclear Energy Institute. The second reason for the improved industry capacity factor, he adds, is the continued improvement in equipment reliability, which means fewer forced outages at the plants.

CAPACITY FACTORS OF THE TOP 20 PERFORMERS

Plant Capacity Factor

Callaway 102.4
Prairie Island 2 101.5
Nine Mile Point 1 99.4
San Onofre 2 99.3
Farley 2 99.3
Catawba 1 98.9
Fort Calhoun 1 98.4
ANO 1 98.3
Byron 2 98.2
Beaver Valley 2 97.8
Peach Bottom 3 97.8
Vermont Yankee 97.7
San Onofre 3 97.0
North Anna 2 96.4
Grand Gulf 1 96.0
Nine Mile Point 2 96.0
Three Mile Island 95.7
Millstone 3 94.5
Comanche Peak 1 93.0
LaSalle 2 92.9