David Lochbaum, director of the Nuclear Safety Program at Union of Concerned Scientists, is one of the nation's top independent nuclear power safety experts.In preparatory research for a U.S. Nuclear Regulatory Commission (NRC) staff-FirstEnergy Nuclear Operating Company (FENOC) meeting on Dec. 17, 2015, regarding Emergency Diesel Generator (EDG) concerns at the problem-plagued Davis-Besse atomic reactor on the Lake Erie shore in Oak Harbor, OH, Michael Keegan of Don't Waste MI uncovered an April 10, 2015 NRC staff Component Design Basis Inspection Report.
Upon reviewing the inspection report, David Lochbaum (photo, left), director of the Union of Concerned Scientists Nuclear Safety Program, and a long time watchdog on Davis-Besse, had this to say:
"I typically review the inspection reports on the NRC's component design basis inspections (CDBIs) because I think they are the best inspection the NRC conducts. Evidence of their goodness is that they used to be conducted at each site every two years. For the past few years, that frequency has been reduced to once every three years. A lot of resources go into the CDBIs. Best of all, the CDBIs use consultants instead of NRC staff (in other words, they are conducted by people who don't have to give a damn about not irking NRC senior managers who control bonuses and promotions).
Oddly enough, even though the CDBI team wrote that it looked at the battery charger and load calculations to check whether there was sufficient voltage to close the EDG output breaker, they didn't notice that there's insufficient voltage to close the output breaker. FirstEnergy's April 1, 2015, license amendment request seeks to provide sufficient voltage.
[Background: The output breakers connect the emergency diesel generator to their respective 4,160 volt electrical buses. In the schematic [see "Davis-Besse Electrical Distribution System," linked here], AC101 is the output breaker for emergency diesel generator 1 while AD101 is the output breaker for emergency diesel generator 2. These output breakers are open when the EDGs are in standby. The electrical buses are supplied from the 13,800 volt buses via the bus tie transformers. When electrical power is lost or degraded, the EDGs automatically start. When they are running and developing proper voltage <at the heart of the license amendment request issue> the output breakers close to re-power the 4160 volt buses. The output breakers are opened and closed automatically using electricity. The license amendment request seeks to increase the minimum voltage for the EDGs from 4031 volts to 4070 volts. The torque required to move the output breaker from its open position to the closed position may require more force than can be provided by 4031 volts. The station blackout events at Vogtle Unit 1 [in Georgia, U.S.A.] in the early 1990s and at Forsmark [in Sweden] a decade later were caused when offsite power was lost and the onsite EDGs started but their output breakers failed to close. Those causes were different from Davis-Besse's insufficient voltage cause, but the consequences are the same -- the EDGs are transformed from sources of electricity into expensive room heaters.]
Check out the first line on page 6 [page 9 of 41 on PDF counter]: "The [CDBI] constituted 19 samples...".
What 19 samples? Selected alphabetically or drawn out of a hat? Nope.
Per the middle of page 5 [page 8 of 41 on PDF counter], "...the selection was based upon the components and operator actions having a risk achievement worth of greater than 1.3 and/or a risk reduction worth greater than 1.005...".
In other words, the samples are highly important stuff and not little bitty stuff.
Turning back to page 2 [page 5 of 41 on PDF counter]: "Five Green findings were identified by the inspectors...".
[Green findings are defined as a finding, or safety violation, of so-called "very-low safety significance." The NRC has also stated (see Inputs to the Assessment Process): "Green inspection findings indicate a deficiency in licensee performance that has very low risk significance and therefore has little or no impact on safety."]
So, looking at 19 highly important things from a safety standpoint revealed 5 safety violations.
It's safe to assume that even Davis-Besse tries harder on the highly important stuff than it does on the only high importance stuff. Their best effort yields a 73.7% grade (14 okay out of 19 tries).
If so, looking at 19 high importance things would likely have identified more than 5 safety violations.
And looking at 19 moderately important things would have likely identified even more safety violations."