Prairie Island is one of two nuclear power plants in Minnesota (the other being Monticello Nuclear Generating Plant in Monticello). Prairie Island has attracted controversy in the early 21st century for its operator Xcel Energy's decision to store nuclear waste in large steelcasks on-site. As this area is a floodplain of the Mississippi, many opponents of the decision fear the risk of water contamination through breach of the casks during seasonal flooding of this important river. They opposed renewal of the federal license at the Prairie Island facility.
In April 2008, Xcel requested that the U.S. Nuclear Regulatory Commission (NRC) renew the licenses of both reactors, extending them for an additional twenty years. The license renewals were approved in June 2011.[2][3]
The company has also requested NRC approval to use a similar storage system at its Monticello plant, which is currently licensed through 2030.
In May 2006 repair workers at the plant were exposed to very low levels of radiation due to inhalation of radioactive iodine-131 (131I) gas. The gas leaked from the steam generators, which were opened for inspection. 131I gas is normally removed by means of a carbon-based filter; in this case the filter had developed a small leak. The NRC deemed this event to be of very low safety significance. It said that no overdose of radiation resulted in any of the workers.[4]
The winter net electrical generation is 560 MW (Unit 1) and 554 MW (Unit 2). The gross electrical generation for both units is 592 MW.[5]
Electricity Production
Generation (MWh) of Prairie Island Nuclear Generating Station[6]
Year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual (Total)
2001
618,437
389,471
812,451
768,863
501,550
676,953
765,082
390,035
626,635
805,604
745,222
812,402
7,912,705
2002
802,932
373,880
783,818
756,917
784,939
748,625
767,063
778,860
762,582
806,927
578,200
724,524
8,669,267
2003
806,522
732,916
800,615
684,367
783,901
750,041
775,166
767,157
509,328
634,237
781,912
811,156
8,837,318
2004
812,077
742,272
813,087
754,093
776,582
731,996
778,077
753,226
469,661
398,624
423,888
807,037
8,260,620
2005
803,697
587,802
725,050
533,350
395,669
605,329
773,229
779,765
752,870
809,297
783,285
810,958
8,360,301
2006
768,648
523,355
812,343
704,490
389,748
663,369
745,076
775,984
755,986
791,112
565,065
615,691
8,110,867
2007
810,954
732,049
677,891
688,004
594,354
745,714
775,685
779,896
742,574
815,304
787,799
760,507
8,910,731
2008
810,496
515,086
469,069
762,392
772,758
743,236
756,823
743,293
609,678
399,754
728,946
807,291
8,118,822
2009
807,196
726,201
805,405
762,882
680,521
745,867
779,578
774,487
506,146
399,117
457,420
806,141
8,250,961
2010
805,145
728,923
805,049
574,465
439,846
741,930
769,667
770,378
761,566
798,544
768,646
818,774
8,782,933
2011
818,468
739,817
815,576
757,785
372,204
597,462
748,386
783,362
774,064
586,553
794,267
814,303
8,602,247
2012
820,337
630,540
407,372
389,424
397,135
730,575
770,451
683,077
767,873
673,038
384,267
399,327
7,053,416
2013
740,979
739,154
815,212
779,072
754,238
701,865
705,139
707,944
569,678
403,634
395,787
401,441
7,714,143
2014
721,609
743,538
816,214
756,998
708,398
749,968
788,820
788,306
768,579
486,688
476,118
577,964
8,383,200
2015
750,900
577,036
498,893
421,236
653,048
631,448
786,848
790,719
770,421
610,077
393,458
490,627
7,374,711
2016
395,781
450,899
805,213
778,932
789,139
758,513
790,015
792,433
776,208
586,692
514,685
824,548
8,263,058
2017
800,052
746,308
814,592
712,816
721,001
734,256
788,068
796,150
730,330
571,144
504,490
825,524
8,744,731
2018
825,623
746,420
807,946
786,128
787,237
760,376
791,122
784,577
612,472
449,168
802,370
829,866
8,983,305
2019
830,379
749,984
826,877
767,210
796,204
768,510
794,271
792,739
709,597
469,769
803,828
830,604
9,139,972
2020
830,631
776,447
820,843
779,680
787,499
751,478
786,644
725,466
566,087
630,500
800,735
827,964
9,083,974
2021
829,359
748,821
826,536
788,422
791,957
758,411
812,448
786,454
708,566
415,370
802,809
830,760
9,099,913
2022
830,920
750,383
816,081
788,362
794,680
762,851
789,948
794,008
768,203
560,237
665,926
829,333
9,150,932
2023
830,915
748,646
830,051
789,354
726,347
572,628
789,879
786,369
761,937
294,027
0
0
7,130,153
2024
0
311,670
660,507
772,807
Surrounding population
The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone has a radius of 10 miles (16 km), and is related primarily to exposure to, and inhalation of, airborne radioactive contamination. Secondly, an ingestion pathway zone with a radius of about 50 miles (80 km), is concerned primarily with ingestion of food and liquid by residents that could be contaminated by radioactivity.[7]
The 2010 U.S. population within 10 miles (16 km) of Prairie Island was 27,996, an increase of 4.6 percent in a decade, according to an analysis of U.S. census data for MSNBC. The 2010 U.S. population within 50 miles (80 km) was 2,945,237, an increase of 7.8 percent since 2000. Cities within 50 miles include Minneapolis (39 miles to city center) and St. Paul (32 miles to city center).[8]
When those casks filled, Xcel Energy requested that the limit be expanded beyond 17 casks. The legislature granted the request, but required the company to make greater use of renewable energy in generating power, such as wind power. In addition, it was required to pay the adjacent Prairie Island Indian Community up to $2.25 million per year to help with evacuation improvements, and the acquisition and development of new land for their reservation. In addition, this money was to help pay for a health study and emergency management activities by the small tribe.
Steam generator replacement
Operators at Prairie Island Nuclear Generating Plant began a refueling outage on Unit 2 at 12:01 a.m. 9/23/2013. In addition to refueling the reactor, an expanded workforce replaced the unit's two steam generators.[10] Unit 2 was expected to come back online within eight weeks; however, it did not resume operation until January 13, 2014. At 2 am on January 14, Unit 2 reached 100% power output.[11]
Seismic risk
The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Prairie Island was 1 in 333,333, according to an NRC study published in August 2010.[12][13]
Emergency shutdowns
Xcel Energy performed an emergency shutdown in late January 2015 of the Unit 1 reactor after a cloud of steam built up in the pressurized cooling system following a cooling-down process to replace a seal in one of the reactor cooling pumps. The plant returned to full power in February 2015.[14]
Unit 2 of the plant has been shut down due to an emergency on 5 March 2015, indicated by a fire alarm at 4:00 am CST. Xcel energy plant operators declared a “notification of an unusual event,” the lowest of four emergency classifications established by the U.S. Nuclear Regulatory Commission.[15]
Unit 2 shut down automatically December 17, 2015, due to a turbine problem, and the fire alarm went off at the time. Operators declared a "notification of unusual event".[16]