Posted on 03/13/2011 1:50:40 PM PDT by SteveH
American Nuclear Society Backgrounder:
Japanese Earthquake/Tsunami; Problems with Nuclear Reactors
3/12/2011 5:22 PM EST
To begin, a sense of perspective is needed… right now, the Japanese earthquake/tsunami is clearly a catastrophe; the situation at impacted nuclear reactors is, in the words of IAEA, an "Accident with Local Consequences."
The Japanese earthquake and tsunami are natural catastrophes of historic proportions. The death toll is likely to be in the thousands. While the information is still not complete at this time, the tragic loss of life and destruction caused by the earthquake and tsunami will likely dwarf the damage caused by the problems associated with the impacted Japanese nuclear plants.
What happened?
Recognizing that information is still not complete due to the destruction of the communication infrastructure, producing reports that are conflicting, here is our best understanding of the sequence of events at the Fukushima I‐1 power station.
* The plant was immediately shut down (scrammed) when the earthquake first hit. The automatic power system worked.
* All external power to the station was lost when the sea water swept away the power lines.
* Diesel generators started to provide backup electrical power to the plant’s backup cooling system. The backup worked.
* The diesel generators ceased functioning after approximately one hour due to tsunami induced damage, reportedly to their fuel supply.
* An Isolation condenser was used to remove the decay heat from the shutdown reactor.
* Apparently the plant then experienced a small loss of coolant from the reactor.
* Reactor Core Isolation Cooling (RCIC) pumps, which operate on steam from the reactor, were used to replace reactor core water inventory, however, the battery‐supplied control valves lost DC power after the prolonged use.
* DC power from batteries was consumed after approximately 8 hours.
* At that point, the plant experienced a complete blackout (no electric power at all).
* Hours passed as primary water inventory was lost and core degradation occurred (through some combination of zirconium oxidation and clad failure).
* Portable diesel generators were delivered to the plant site.
* AC power was restored allowing for a different backup pumping system to replace inventory in reactor pressure vessel (RPV).
* Pressure in the containment drywell rose as wetwell became hotter.
* The Drywell containment was vented to outside reactor building which surrounds the containment.
* Hydrogen produced from zirconium oxidation was vented from the containment into the reactor building.
* Hydrogen in reactor building exploded causing it to collapse around the containment.
* The containment around the reactor and RPV were reported to be intact.
* The decision was made to inject seawater into the RPV to continue to the cooling process, another backup system that was designed into the plant from inception.
* Radioactivity releases from operator initiated venting appear to be decreasing.
Can it happen here in the US ?
* While there are risks associated with operating nuclear plants and other industrial facilities, the chances of an adverse event similar to what happened in Japan occurring in the US is small.
* Since September 11, 2001, additional safeguards and training have been put in place at US nuclear reactors which allow plant operators to cool the reactor core during an extended power outage and/or failure of backup generators – “blackout conditions.”
Is a nuclear reactor "meltdown" a catastrophic event?
* Not necessarily. Nuclear reactors are built with redundant safety systems. Even if the fuel in the reactor melts, the reactor's containment systems are designed to prevent the spread of radioactivity into the environment. Should an event like this occur, containing the radioactive materials could actually be considered a "success" given the scale of this natural disaster that had not been considered in the original design. The nuclear power industry will learn from this event, and redesign our facilities as needed to make them safer in the future.
What is the ANS doing?
ANS has reached out to The Atomic Energy Society of Japan (AESJ) to offer technical assistance.
ANS has established an incident communications response team.
This team has compiling relevant news reports and other publicly available information on the ANS blog, which can be found at ansnuclearcafe.org.
The team is also fielding media inquiries and providing reporters with background information and technical perspective as the events unfold.
Finally, the ANS is collecting information from publicly available sources, our sources in government agencies, and our sources on the ground in Japan , to better understand the extent and impact of the incident.
http://www.new.ans.org/
ANS Blog
http://ansnuclearcafe.org/
I’m very pro nuclear. Very. But there are 23 reactors in the US similar to the Japanese reactors. I take no comfort that the risk is “small”.
I don’t believe we can make the risk zero, but it should be less than “small”.
We make the risk smaller by trial and error sometimes. Sad to say that it’s calamities like this that reveal weaknesses. And sometimes it takes such calamities to correct the weaknesses.
Bump for later
Thanks for some coherent and objective news on the subject.
There’s a couple more good sources in this thread;
http://www.freerepublic.com/focus/news/2687936/posts?
BTTT
Thanks for post this information.
OK.
1. Quantify how much less than “small” you want it. If you can’t quantify it, then it can’t be done. So quantify it.
2. How much do you want to pay for going from “small” to “less than small” in your electric bill?
I agree with a vehemence most furious.
While the media is off flapping their jaws on things they know less than nothing (because math and science were too ‘hard’ for them in school), they’ve ignored such things as FOUR trains were swept away. Thousands of people are likely dead in the rubble of their homes, and perhaps hundreds to thousands more who were in those trains.
Cropland that Japan needs for growing food (they don’t have much cropland to begin with) now has to have the salt washed out of the soil before it will grow food at prior yields. There’s millions of tons of debris that have to be dealt with, and they don’t have much place to put it.
On and on and on. Yet the press wanted to hyperventilate about a non-disaster and get a whole bunch of ignorant people in the US whipped into an anti-nuke frenzy.
In an accident, how much radiation and how many deaths are you willing to accept?
I’m going to repeat that I’m a strong supporter of nuclear reactors. We need a lot more of them in the US. They are our future.
I’ll accept a level of death on par with the current level of deaths in coal mining, transport, coal power plant operations, etc, measured as “deaths per megawatt/hour produced power.” I’m not going to listen to any twaddle from “epidemiological studies” and projections of how many people supposedly die from coal plant emissions. That’s statistical horsecrap and hand-waving.
If we’re going to offset coal-fired plants with nukes, then it follows that we don’t want to make the mortality rate any higher than it is for the production of the same amount of power by coal.
Given the nuclear industry’s track record, I’m on pretty safe ground when I expect that the mortality rate per MWh will be lower than that for coal.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.