Why do some nuclear power plants have smoke stacks?

[Hiddencamper]

I'd thought the noble gases were not scrubbed from either nuclear plants or nuclear fuel processing facilities. Is this incorrect?
The document here: http://www.areva.com/EN/operations-2332/gaseous-releases-annual-statement.html suggests the release by the Areva La Hague processing facility is about 280,000 Terabequerels of noble gases, 3,000 times as much as the tritium and C14 releases.

That's correct. My argument is a passive filter vent at Fukushima would not have changed the outcome. Japan would not have vented early when they should have, because the noble gas release still would have been high, even with a passive filter. Later in the event the containment systems were damaged precluding effectiveness of a passive filter. It would not have substantially decreased the release either in the actual case of a hypothetical case.

 

[etudiant]

Why would concern about a noble gas release prevent the Japanese from venting early given the presence of a passive filter for the other emissions?
Is there some legal or health constraint?

 

[mheslep]

I imagine Xe-135, w/ half life of some hours, is the primary concern

 

[Hiddencamper]

Why would concern about a noble gas release prevent the Japanese from venting early given the presence of a passive filter for the other emissions?
Is there some legal or health constraint?

In Japan you need to get permission to vent containment.

There is an argument out there that if the plants had a filtered vent, they would have been more likely to vent early when it would have helped. But this isn't true because the government still controlled when the first vent occurred and you still would have had a large noble gas release.

I think it's unlikely that the Japanese government would have allowed early venting even with an installed filter.

 

[nikkkom]

Seems to me Fukushima makes HC's point, not yours, as in that case what additional safety is provided by filters whose function clearly would have become moot when the containment seal was blown at the time of the explosions? To my mind the lesson of Fukushima is the guaranteed removal of sufficient decay heat before it induces a destructive explosion, not the indeterminate use of what remains after an explosion.

Wrong.

I read Fukushima accident timeline.

Personnel was afraid to vent the containment because they knew this will result in some of-site contamination. So for a time they were hoping they can be able to contain the accident without venting. When they realized it's not to be, they did not have enough time to organize orderly venting happen.

So it all ended as an uncontrolled venting through damaged containment.

You may notice that Japanese are now installing filters on all vent lines on all NPPs. Looks like they agree with me, not with NRC.

 

[Hiddencamper]

Wrong.

I read Fukushima accident timeline.

Personnel was afraid to vent the containment because they knew this will result in some of-site contamination. So for a time they were hoping they can be able to contain the accident without venting. When they realized it's not to be, they did not have enough time to organize orderly venting happen.

So it all ended as an uncontrolled venting through damaged containment.

You may notice that Japanese are now installing filters on all vent lines on all NPPs. Looks like they agree with me, not with NRC.

U.S. SAGs and EOPs for boiling water reactors have you vent prior to exceeding the PCPL. Unlike Japan which has you wait until you are twice the PCPL. (Primary containment pressure limit). Twice the PCPL is the ultimate design limit of the containment for the mark I/II plants.

Just that directive alone, the difference in the emergency procedures, creates problems. And they were waiting for approval to vent after they decided to.

 

[mheslep]

Wrong.

I read Fukushima accident timeline.

Personnel was afraid to vent the containment because they knew this will result in some of-site contamination. So for a time they were hoping they can be able to contain the accident without venting. When they realized it's not to be, they did not have enough time to organize orderly venting happen.

So it all ended as an uncontrolled venting through damaged containment..

That all may be true, but what does any of it have to with the one relevant point, which is how do the filters help in any way to prevent a Fukushima like accident. Namely, the rejection of the decay heat after loss of cooling.