Flaws discovered in Palisades nuclear plant's coolant system
There are more problems reported at the Palisades nuclear power plant along the Lake Michigan shoreline.
The Nuclear Regulatory Commission says it found flaws in nearly a third of the control rod drive mechanism housings it inspected at the plant just north of the Berrien County line.The mechanisms with the flaws are part of the reactor's coolant system -- designed to prevent reactor coolant from leaking into the containment, according to the NRC.The NRC says it didn't find any evidence of a leak, and the "issue has no adverse effect on plant or public safety."
A company spokesperson says all 17 of the faulty housings will be replaced.These inspections happened while the plant was off-line for maintenance and refueling.
Here is the full release from the NRC:
On January 29, 2014, Entergy Nuclear Operations, Inc., notified the NRC 9 http://www.nrc.gov/reading-rm/doc-collections/event-status/event/en.html ) that the licensee found flaws during planned examinations of control rod drive mechanism (CRDM) housings that required further review and evaluation. The CRDMs are part of the reactor coolant system boundary designed to prevent reactor coolant from leaking into the containment. At present, there is no evidence of leakage. The examinations were conducted in accordance with the licensee's corrective actions documented in an NRC inspection report following a leak from a CRDM housing in 2012.
This issue did not cause the plant to shut down. The plant was already shut down for a refueling outage when the CRD housing exams were performed and remains shut down as the refueling outage work continues. This issue has no adverse effect on plant or public safety.
Two resident inspectors are assigned to the site full-time to inspect and assess all licensee activities. To supplement the resident inspectors' efforts during the refueling outage, the NRC has two specialist inspectors on site to inspect and assess the plant's outage activities. One of these specialist inspectors was on site to specifically observe the CRDM housing examinations. This NRC specialist continues to independently inspect and evaluate the licensee's response.
There are 45 CRDMs, one associated with each control rod. The control rods, when inserted into the reactor, are designed to absorb neutrons to control the nuclear reaction. The CRDMs extend from the reactor head to about 14 feet upward, and are the mechanisms that withdraw and insert the control rods. The flaws are in the CRDM housings above the reactor head, and not in the reactor head itself.
After inspecting all 45 CRDM housings, the licensee concluded that there are flaws in 17 of the 45 housings.
NRC inspectors have been reviewing the plant's inspections and assessments and are reviewing the licensee's replacement and repair plans, which will be completed prior to plant startup. The NRC will continue to evaluate and validate the licensee's response to the issue to ensure plant safety. The NRC will document its conclusions in a publicly available inspection report.