NRC plans special inspection of cracking at Davis-Besse nuclear power plant

[AnOhioan]

Source: Cleveland Plain Dealer

The Nuclear Regulatory Commission will do a special inspection to investigate the new cracking problems at the Davis-Besse nuclear power plant.

The agency's top expert on reactor lid problems is joining an NRC Chicago-based metallurgist already at the Toledo-area plant.

Owner FirstEnergy Corp. shut down the plant for scheduled refueling and maintenance Feb. 28.

Contractors doing NRC-mandated ultrasonic inspections of alloy sleeves that carry control rods through the heavy carbon steel reactor lid found indications of cracks in 14 of the tubes, known as nozzles because of their shape.

Read more: http://www.cleveland.com/business/index.ssf/2010/03/nrc_plans_special_inspection_o.html

[rhett o rick]

1. An investigation, oh wow. I feel soooo much better. nm

[kristopher]

2. What REALLY caused the hole in the reactor head?

UCS -- Aging Nuclear Plants -- Davis-Besse: The Reactor with a Hole in its Head

What REALLY caused the hole in the reactor head?
Complacency on the part of the plant's owner and the NRC really caused the hole in the reactor head.

● Evidence of complacency by the plant's owner includes:
When problems with leaking CRDM flanges surfaced years agon, workers at Davis-Besse proposed a
modification that would enable better inspections of the reactor vessel head. Management approved this
modification, but then deferred its implementation.

● When boric acid crystals were repeatedly found coating the outer surface of the reactor vessel head,
workers at Davis-Besse merely tried cleaning them away. The plant's design required all components
coming into contact with reactor water to be made of corrosion-resistant materials or to be clad with a
protective layer of stainless steel. The outer surface of the reactor vessel head was neither
corrosion-resistant nor coated with stainless steel. Management tolerated a degraded condition prohibited
by the plant's design.

● Armed with knowledge about leaking CRDM flanges at Davis-Besse causing the outer surface of the
reactor vessel to be coated with boric acid crystals, about the high likelihood that one or more CRDM
nozzles would be cracked, and about elevated iron oxide levels within the containment building,
management begged the NRC in fall 2001 to allow it to skip the reactor vessel head inspection mandated
by the end of the year.

Evidence of complacency by the NRC includes:
● Less than two years after another similarly skipped inspection contributed to an accident at the Indian Point
2 nuclear plant, the NRC allowed Davis-Besse to skip the mandated 2001 year-end inspection.

● After CRDM nozzle cracking was reported at Bugey Unit 3 in 1991, the NRC initiated a research program
to examine the issue for US reactors. As the NRC research program was plodding along, Greenpeace
International petitioned the NRC on March 24, 1993, to require inspections of CRDM nozzles at all US
reactors and to make the inspection results publicly available. Greenpeace also sought to shut down all
reactors with cracked nozzles. The NRC denied Greenpeace's requests nearly two years later.<3>

● NRC denied Greenpeace's petition in large part because of a research report prepared by the Idaho
National Engineering Laboratory for the NRC. This report, released in October 1994, concluded "CRDM
nozzle cracking is not a short-term safety issue. All the detected cracks on the nozzle inside surface are
axially oriented. ...Some analyses have shown that short, circumferential cracks on the outside surface are
possible; however, these cracks are not expected to grow through-wall...." At the time of this conclusion, a
grand total of one (1) US nuclear plant (Point Beach Unit 1in Wisconsin) had been inspected for CRDM
nozzle cracking.<4>

● After large, through-wall, circumferential cracking was found on the outside surface of two CRDM nozzles
at Oconee Unit 3 in August 2001, the NRC asked plant owners to write them about inspections of CRDM
nozzles and the extent of identified cracking. In essence, the NRC only did part of what Greenpeace asked
eight years earlier.

● After a huge gaping hole was found in the reactor head at Davis-Besse, the NRC finally sought the
inspections that Greenpeace requested nine years earlier.

UCS -- Aging Nuclear Plants -- Davis-Besse: The Reactor with a Hole in its Head