ScribbleLive

@Peter are there more than one rupture disks ?

@lillymunster you said "Just read it. Hole in containment on top of the hole in the suppression pool." this is not clear for me :)

@Peter a rupture disk behind the valves ? does this make sense ? i would prefer it parallel to the valves.

this all makes no sense. if there is a hole in the drywell, how can pressure build up 7 atmospheres in torus ?

@Ian :-)

www.westinghousenuclear.com for lilly, Edano, elaine Ian and others

www.nytimes.com good write up with interactive features on venting failure at fuku

@Peter I thought the rupture disks were somewhere in the down vents to the torus. I really need more coffee. :-) If it is an inline rupture disc in the venting system past containment that would make more sense in a way. I know I read something about how drywell and torus balance pressure between the two. Let me go dig through my notes.

@ lilly and @ Peter,, here is a statement concerning rupture disc failure and then not being able to close an isolation valve like in FUKU....If a vent sticks open or if the containment breaches, the emergency core cooling system pumps will fail to cool the core if they rely on the overpressure credit,’’ he said.
If the vent is operated with an electrically driven valve, as in the current design, operators can control how much steam they let out and how much pressure they keep in. The alternative is probably a rupture disk, a thin piece of steel that breaks at a pre-designed level, just below the pressure that is likely to rupture the containment.
In a system that relies on a rupture disk, a valve left in the open position would also be installed. If the disk ruptured, the only way to re-close the system would be to close the valve. But just as the Fukushima operators discovered that in an accident there may be no way to open a valve, some experts fear that in another accident, with a rupture disk having performed its function, there would not be a way to close the valve.

From what I am reading in the NRC document each torus down vent tube has a staged valve that should open at a certain containment pressure into the torus.

Two "vents" being discussed and getting a bit confusing when reading. The venting system we have been talking about that they have to manually vent to relieve pressure. The down vent tubes from the drywell to the torus have some sort of pressure sensitive vent that should open with enough drywell pressure. Why the drywell would get to almost double design pressure and the torus still be at a much lower pressure is odd. Those vents should have opened and allowed the steam and pressure down into them.

Does anyone know the concrete composition in the reactors at Fuku? ie: limestone & sand, just limestone, basaltic etc?

Still reading the corium document. It mentions that the melting of concrete and released vapors from it are a far larger source of things (gasses aerosols) released into containment. So concrete interaction could be playing a much larger role in the containment failures and explosions than initially assumed.

NRC TO HOLD MANDATORY HEARING REGARDING VOGTLE
NEW REACTOR APPLICATION SEPT. 27-28 IN ROCKVILLE, MD
The Nuclear Regulatory Commission will conduct a mandatory hearing on Tuesday,
Sept. 27, and Wednesday, Sept. 28, on an application for Combined Licenses (COL) and related
Limited Work Authorizations (LWA) to build and operate two new reactors at the Vogtle site
near Waynesboro, Ga. The Vogtle application is the first to reach this final step in the Part 52
new reactor licensing process.
“This mandatory hearing on the first COL application represents a critical step in the
NRC’s license review process,” said NRC Chairman Gregory B. Jaczko. “I look forward to
working with my colleagues as we approach this significant assignment of delving into the
adequacy of the NRC staff’s review of this application.”
The Commission’s hearing will include testimony and exhibits from the applicant,
Southern Nuclear Operating Company (SNC), and NRC staff on the question of whether the
staff’s review has been adequate to support the findings necessary to issue a COL and/or a LWA.
The hearing will begin at 9 a.m. on Sept. 27 in the Commissioner’s Conference Room at
NRC Headquarters, 11555 Rockville Pike, Rockville, Md. The Commission expects to discuss
the staff’s Final Safety Evaluation Report (FSER) on the first day, with discussion of the staff’s
Final Supplemental Environmental Impact Statement (FSEIS) starting on Sept. 28. The hearing
will be open to public observation and will be webcast. A detailed agenda and presentation slides
will be available in advance on the Commission’s meeting transcript page.
SNC is applying for permission to build and operate two AP1000 reactors at the Vogtle
site, adjacent to the company’s existing reactors approximately 26 miles southeast of Augusta,
Ga. SNC submitted its COL application for Vogtle on March 28, 2008, and supplemented the
application on Oct. 2, 2009. The LWA would authorize a specific set of activities that fall short
of full reactor construction. Westinghouse submitted an application to amend the alreadycertified AP1000, a 1100 megawatt electric design, on May 26, 2007. More information on the
AP1000 amendment review is available on the NRC website.
The NRC’s Advisory Committee on Reactor Safeguards (ACRS) independently reviewed
aspects of the application that concern safety, as well as an earlier version of the FSER. The
ACRS provided the results of its review to the Commission in a report dated Jan. 24. The NRC

@dean it is taking a while to work though the doc when I have time here and there but it has tons of relevant info. When I am done I will post notes from it. I think it will help flesh out a bunch of different things.