All nuclear plants in the U.S. continued to operate safely, the Nuclear Regulatory Commission (NRC) said as it announced it had issued mid-cycle assessment letters to the nation’s 104 operating commercial nuclear plants.

In the mid-cycle assessment period that concluded on June 30, 99 of 104 plants were in the two highest performance categories. Ninety-one plants were performing at the highest level and are being inspected by the NRC using the normal detailed level inspection program. Eight plants performed at the next highest level, needing to resolve one or two items of low safety significance, and will receive additional inspection and attention to follow up on corrective actions. These plants were: Brunswick 1 and 2 (N.C.); Byron 2 (Ill.); Cooper (Neb.); Ginna (N.Y.); Millstone 2 (Conn.); Prairie Island 1 (Minn.); and Turkey Point 4 (Fla.).

Three nuclear reactors were at the third level of performance, with one degraded safety cornerstone, and will receive more NRC inspections, senior management attention, and oversight focused on the cause of the degraded performance. These plants were: H. B. Robinson 2 (S.C.); Perry 1 (Ohio); and Susquehanna 1 (Pa).

Two plants, Browns Ferry Unit 1 (Ala.) and Fort Calhoun (Neb.), require the NRC’s highest level of attention, which will include additional inspections to confirm the plant’s performance issues are being addressed.

In addition, mid-cycle letters were also sent to both the Watts Bar Unit 2 site (Tenn.) and the Vogtle Unit 3 and 4 site (Ga.), reviewing activities associated with early site permits and limited work authorized by the NRC.

The NRC noted that some plant ratings have changed since the last day of the assessment period. Robinson 2, for example, has resolved the performance issues and has transitioned from the third level to the second level of performance. Brunswick Units 1 and 2, and Turkey Point Unit 4 have also resolved their issues that prompted increased regulatory oversight. All three units have since transitioned to the highest performing level.

Every six months each plant receives either a mid-cycle review letter or an annual assessment letter, along with an NRC inspection plan. The next annual assessment letters will be issued in March 2012.

Sources: POWERnews, NRC