# N&O: Unqualified Progress Energy workers caused fluke mishap at Brunswick nuclear plant

Submitted: Fri, 01/27/2012 - 4:26am
Updated: Fri, 01/27/2012 - 5:48pm
By:

RALEIGH, NC (NEWS & OBSERVER) — Nuclear safety officials have concluded that a fluke mishap last year at Progress Energy’s Brunswick nuclear plant near Wilmington was caused by the lack of worker qualification for more than a decade.

The Nuclear Regulatory Commission issued its preliminary findings yesterday, but the federal safety agency is continuing its investigation to determine the safety significance of the incident.

The unusual mishap that shut down the Brunswick Unit 2 reactor last November may be the only such incident in U.S. nuclear history.

• Brian says:

My comment below was regarding hydraulic torquing tools, but you may be correct in your statement that the bolts are actually tensioned. For that procedure, a hydraulic cylinder is attached to the bolt, and it pulls the bolt with a specified amount of force. These tensioning heads also have a conversion table – tensile force converted to hydraulic pressure. So for example if the surface area of the hydraulic piston is 10 square inches, then 13000 psi of hydraulic pressure would exert 130000 pounds of tensile force on the bolt. This is a more accurate method of fastening than the hydraulic torquing. It has been my experience that the tensioning procedure seems to be even less understood by the workers than torquing.

• Guest461 says:

The reference in the link reports the torquing of bolts in the units of PSI (pounds/square inch) which is a measure of pressure against one square inch of surface area. “Torque” is represented as either inch/pounds or foot/pounds (or metric equivelent) and equates to the amount of force applied to the given moment arm of feet or inches as the applicable torque value requires. The end result of torquing a bolt or stud imposes a tensile stress value represented in PSI, but that is a resultant, calculated value based on the ft/lb of torque imposed.

If you report a story of a technical nature, especially regarding the nuclear power industry, report it with knowledge, accuracy and some sense of reliability.

• Brian says:

Believe it or not, most of the workers don’t understand this either. The hydraulic torquing tools that are used for this work have heads that convert hydraulic pressure into torque. They come with tables that allow the operator to cross reference a specific torque value to a particular pressure at the head, measured either in PSI or KPa. Workers are typically given the pressure value, but not the actual torque required. I worked in the wind industry, and we use hydraulic torque tools for most of the structural fasteners. Nobody I worked with that used those tools understood this. They just knew they needed to ‘run it up to 3000 kips’, but they couldn’t explain what it meant or why. It’s a little scary if you ask me.

• Guest889988 says:

you work nuclear power?

if i remember correctly the RV head bolts are “stretched” to 13,000 PSI, then the nuts tightened down over them. hence the 13,000 PSI in the report. not just tightened like a regular bolt. think about it….. if they were tightened to 1300 Ft/LB there’s no way they would be able to “loosen them by hand” (as stated in the article). 1300 wouldn’t even begin to stretch the massive bolting on the head.

• Guest461 says:

It should be known that ZERO work in or on a nuclear reactor is ever performed by any one individual. The operation is performed, the operation is witnessed by quality and the operation is verified as complete and acceptable by quality to include the physical sign-offs of documentation. This is not a one-man, unsupervised “tighte’m up bud” procedure. It involves the oversight of many peers over multiple, complex operations prior to going back into service. Point the finger as you like.

Oh yeah…one simple reiminder here…the leak was 10 Gallons per minute. Your average morning shower as you soap up is ~20 GPM.

• Guest666 says:

What are you useing for a shower head, a water main?

• guesty says:

Federal regulations mandate that new showerhead flow rates can’t exceed more than 2.5 gallons per minute (gpm) at a water pressure of 80 pounds per square inch (psi). New faucet flow rates can’t exceed 2.5 gpm at 80 psi or 2.2 gpm at 60 psi.

You must be using a pressure washer in your bathroom.

http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=13050