Byron Nuclear Gen Station Backup Cooling Pumps

[swl]

Do any of you know if the backup water pumps have been upgraded at the Byron NGS?

Also, is the plant currently using the main cooling pumps, or the backup pumps?

Last year after the Fukushima triple meltdown, the NRC told the Exelon that the backup cooling pumps at Byron were too small to cool the reactor in an emergency, and after waffling back and forth on the issue, the operator, Exelon, decided the pumps were indeed too small.

So, are the undersized pumps the reason for their decision to release radioactive steam into the atmosphere? Or is this the normal operating procedure in response to loss of offsite power?

Thanks for any expert guidance.

 

[Astronuc]

BYRON, Ill. (AP) — A nuclear reactor at a northern Illinois plant shut down Monday after losing power, and steam was being vented to reduce pressure, according to officials from Exelon Nuclear and federal regulators.

Unit 2 at Byron Generating Station shut down around 10:18 a.m., after losing power from an off-site source, Exelon officials said. Diesel generators began supplying power to the plant equipment and operators began releasing steam from the non-nuclear side of the plant to help cool the reactor, officials said.

Even though the turbine is not turning to produce electricity, "you still need to cool the equipment." said U.S. Nuclear Regulatory Commission spokeswoman Viktoria Mitlyng. Releasing steam helps "take away some of that energy still being produced by nuclear reaction but that doesn't have anywhere to go now."

The steam contains low levels of radioactive tritium, but the levels are safe for workers and the public, federal and plant officials said.

Source: http://www.newstrib.com/articles/news/nci/default.asp?article=32125

The venting comes from the secondary side, and the apparently the plant is designed to do just that. The coolant in the secondary loop may contain some tritium from the primary coolant side, either from leaks or from the fact that hydrogen diffuses in metals from hotter to cooler.

Venting steam is a quick way to remove heat from the primary system. It appears unit 2 was running at full power, as was Unit 1, when it tripped. The current cycle of Unit 2 began Oct 10, 2011.

 

[swl]

I am pleased to read that there is no danger to the public or plant operators.

Any ideas why http://www.nwherald.com/2012/01/30/power-loss-shuts-down-byron-nuclear-plant-unit-public-in-no-danger/asepmmg/ if there was no danger?

Could the radiation have been more intense near the plant, or could it have been to prevent hearing damage from the sound of the steam release?

 

[jim hardy]

"Any ideas why "Workers were evacuated" if there was no danger?""

my GUESS is it's innocuous, like a fire alarm went off or the office building went dark when offsite power through that transformer was lost..

were there a release there'd have been notification to public agencies.

 

[Astronuc]

I am pleased to read that there is no danger to the public or plant operators.

Any ideas why http://www.nwherald.com/2012/01/30/power-loss-shuts-down-byron-nuclear-plant-unit-public-in-no-danger/asepmmg/ if there was no danger?

Could the radiation have been more intense near the plant, or could it have been to prevent hearing damage from the sound of the steam release?

From the cited source, "Workers were evacuated and Byron and several other area fire departments were on stand by at the scene as precautionary measures, . . . "

I imagine that workers in affected areas were removed as a precaution while the plant was being shutdown.

Meanwhile the NRC will investigate why the plant lost offsite power, and I expect they will review the response of the plant staff in managing the shutdown.
http://www.nrc.gov/reading-rm/doc-collections/news/2012/12-005.iii.pdf