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back greetings to all

YET another approach for seismic analyses and request for commercial plants to follow guidelines to re-evaluate probability risk assessments

good article @ Pedro.. this statement made by a risk advisor tells the story, previous upgrades in seismic analyses have indicated that the plants need upgrades to meet more stringent requirements,,, this was done already and the new analyses may push the cart over the clifffor retrofits.. .
If retrofits are required, they will be expensive. "To go back into some of these older plants and deal with seismic issues might end up costing more than the plants are worth," said Stephen Maloney, a partner at Azoulas Risk Advisors in Boston, a consulting firm that often works with the nuclear industry. That could force such plants to close.

Interesting. NEI was whining about the post Fuku safety changes and hinting they want them weakened or further delayed due to cost. In an article on their website this morning.

@lilly.. how did it go today?

@Pedro good comment

@Pedro Jesus indeed. Peter's article he wrote about current approaches to risk is quite relevant. I don't buy the industry meme that because they think the probability is low it really is. They tend to think a bit too uncreatively at risks. Such as will and earthquake of over 7.0 hit such and such area. When the more important question is what will happen if a set of failures happens like station blackout plus LOCA plus ANY disaster that impedes people and equipment from working.

There is a set of issues compounding on the US nuclear industry (and also in some other places) where post Fuku safety changes are considerable and possibly impossible to do. Those changes are expensive. Earthquake reassessment is being done and may require changes, cost or impossible to fix problems. The spent fuel issue has hit a wall where they can't ignore it anymore and are well past the point of unacceptable public safety risk.

NRC BEGINS SPECIAL INSPECTION AT BYRON NUCLEAR PLANT
The U.S. Nuclear Regulatory Commission has started a Special Inspection to review the circumstances around the loss of offsite power that led to a Unit 2 reactor shutdown on Jan. 30 at the Byron nuclear power plant.
The two-unit plant is operated by Exelon Generation Co. and is located in Byron, Ill., about 17 miles southwest of Rockford.
The special inspection team began work today and will look into how plant equipment responded to the loss of offsite power. They will review the sequence of events, evaluate the facts and circumstances, and review the plants actions surrounding the incident. The team will also review the
plant’s evaluation of what happened, their plan for addressing the cause of the event, and the implementation of their corrective actions.
Unit 2 remains in a safe and stable shutdown condition and the diesel generators continue to supply power to the plant as planned for this type of incident. There was a steam release from the non-nuclear side of the plant with trace amounts of tritium. This type of steam release is used by nuclear power plants to release pressure in order to maintain the plant in a stable condition. Doses to the public from this type of release are significantly below even the most stringent Federal protective limits and, therefore, do not pose a risk to public health and safety. The NRC’s special inspection report will be available within 45 days of the inspection’s completion of through the NRC RIII Office of Public Affairs or through the Agencywide Documents Access and Management System (ADAMS) at the NRC website

VIA nrc email

@lilly.. we could benefit from our group trying to get procedures etc for recovery from an off site power to bryon to work along with what NRC finds. A major event and it's lasted for a long time, perhaps longer that designed.

@dean there are some documents on loss of offsite power from NRC. Would Generic Safety issues documents be useful enough?

status of batteries, problems with operating diesels etc would be good to know from bryon... would be nice to get the daily status sheets somewhoe

@dean I tried to find details on byron's emergency diesels this morning via google and didn't score anything. I may try using the PWR type and see if I can find anything

Appendix A to Part 50—General Design Criteria for Nuclear Power Plants www.nrc.gov

Resolution of Generic Safety Issues: Issue 17: Loss of Offsite Power Subsequent to a LOCA ( NUREG-0933, Main Report with Supplements 1–34 ) www.nrc.gov

@dean looking for details on EDG and other systems

from this document www.nrc.gov

spot on @lilly

erm this looks extremely relevant www.nrc.gov

NRC detailed document "notebook" specifically on the reactor type at Byron pbadupws.nrc.gov

This may have the generator details

3 standby diesel generators and total loss of offsite power is listed in the risk asseessment of the document I just posted

Each of the three standby diesel generators per unit has individual fuel oil storage tanks with enough fuel for seven days'. These tanks are
mounted above the diesel generator bays. The fuel oil is gravity fed to the individual engine driven booster pump and to the standby booster
pump.
5. The BOP diesel generator supplies power to instrument air compressor 12 and the auxiliary cooling water pump. On loss of offsite power,
operator action is necessary to restore these components to operation.