Japan Earthquake

Japan Earthquake | Page 1689

morning Pedro.. morning lilly.. and thanks for that coffee.. sippppppppppppp
by dean 6/19/2011 12:58:33 PM

Heard an interesting bit on the local news. They are having minor levee issues due to wildlife. Deer are walking on the plastic sheeting putting holes in it. Bagers, beavers and foxes are burrowing in the sides. This was up at south Sioux City, wasn't near ft. Calhoun.
by lillymunster 6/19/2011 1:02:04 PM

lilly.. that's probably a beyond design basis accident..
by dean 6/19/2011 1:02:49 PM

one real threat to a nuclear plant is rodents that get inside and then find their way to cable trays and decide to chew up some insulation ... that has happened before
by dean 6/19/2011 1:05:25 PM

that will become a real problem as the plant becomes the only source of warmth iin the area come winter
by elainekirk 6/19/2011 1:16:24 PM

some of the modifications done to the bwr mark 1 reactors from what I see for the added vent line introduce a single failure fault which would render venting capability inoperable... interesting
by dean 6/19/2011 1:17:16 PM

so true elaine, plants need to be constantly vigilant to look for droppings etc or signs of rodents getting into the plant
by dean 6/19/2011 1:18:06 PM

Hi! so how many mods are in here? Doing a mod count lol Deb cant get in next door in mod.
by Angie 6/19/2011 1:23:51 PM

www.beyondnuclear.org Charter for the NRC task force evaluation for near term changes due to fukushima
by dean 6/19/2011 1:24:09 PM

@elainekirk you shuld and go and lay down miss sick girl!
by Angie 6/19/2011 1:25:06 PM

www.gereports.com modifications recommended @ Angie
by dean 6/19/2011 1:28:35 PM

@dean lol ummm yeap allll in double dutch to me! lol
by Angie 6/19/2011 1:30:06 PM

@dean did they know when they modified what the consequence would be?
by ElaineKirk 6/19/2011 1:33:50 PM

lookie at all the pretty icons... nice.. maybe I'll paint a pretty colorful painting
by dean 6/19/2011 1:37:57 PM

I thought some colour might cheer the place up! lol ok off to Uni land for me! be good guys!
by Angie 6/19/2011 1:38:39 PM

elaine.. I'm sure they didn't and that the design would have had some assumptions which as we see were not correct for hypothetical accidents or combination of failures
by dean 6/19/2011 1:38:58 PM

I have to finish the one I started last week.. then will do a nice bright one
by dean 6/19/2011 1:39:48 PM

@dean basically accident avoidance/preparedness wasnt high priority in n earthquake prone country
by ElaineKirk 6/19/2011 1:40:43 PM

www.physicsforums.com @lilly and @all.. check out the entry at 3-25-11, 09:29.. it even has a hand sketched explosion path for 3
by dean 6/19/2011 1:44:20 PM

true elaine, also interesting .. of 23 reactors in the usa who would have made the modifications (which were not mandatory) 22 made them and 1 did not and said they felt they had other mechanisms within the plant to handle that accident situation..
by dean 6/19/2011 1:45:35 PM

@dean I remember hearing early on how the venting system was mandatory in the US but up to plant owners in Japan. This was cited at a failing in Japan, now to find out it was the same situation here?
by lillymunster 6/19/2011 1:47:46 PM

@dean, I found a NRC study on the performance of variuos types of valves: www.nrc.gov
by Peter Melzer 6/19/2011 1:49:45 PM

news.nuclear.com this is No NRC orders were issued to require installation of a hard pipe vent, and all modifications made were voluntarily. Licensees were allowed to justify not installing the hard pipe vent based on plant unique configuration and circumstances. All 23 BWR Mark I plants either installed the modification described in the generic letter (22 plants), or justified use of existing plant safety features (one plant). Installation of the vent was designed to improve safety of the plants in the U.S.
what I just read...
by dean 6/19/2011 1:51:53 PM

The CCI company provides some good idea how they are engineered: docs.google.com
by Peter Melzer 6/19/2011 1:52:36 PM

@dean , hence one item on my list of demands to the operators would be that they report within a month what their existing implementations for hardened vents are at present.
by Peter Melzer 6/19/2011 1:55:08 PM

I saw that document one time Peter, it is a gem... I know from experience that relief valves for high pressure systems are very temperamental and for those big ones at nuc plants, when they lift, the pressure surge and shock on the system is horrendous. It would be good to get the maintenance procedure for some of the bigger SRV's and see how they test them..

by dean 6/19/2011 1:58:13 PM

The Reactor Accident off gas system (shielded filtration - carbon and HEPAs) is within the reactor building. I am assuming it worked until the station black out. Then the valves failed shut. I do not know if they had hydrogen igniters on the system (but doubt). The system is located above the reactor vessel level of the plant. That could have been the location of the first expolsions and when damaged the gas vented naturally to the reactor building via numerous paths, eventually finding their way to the top of the reactor building (reactor work platform area). The other off-gas system is the normal one that allows filtration and decay of radioactive short lived gases and is generally under ground with a long decay loop before heading for the stacks. I have inplant experience with several of the BWR models, but am getting long in the tooth, and my memory gets sketchy at times. Also, I have little patience with conjecture based on hearsay and not facts. A QUOTE from one man on the physics forumn
by dean 6/19/2011 2:01:17 PM