MICHELE NORRIS, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Michele Norris.
ROBERT SIEGEL, host:
I'm Robert Siegel.
And we begin this hour with this news - BP says for the first time in three months, oil has stopped flowing from its damaged oil well in the Gulf. This afternoon, BP engineers closed down the valves on a new cap that's been installed on the remnants of the well.
With me now is NPR's science correspondent Richard Harris, who's been following the spill since the start. And, Richard, tell us at the moment what's happening.
RICHARD HARRIS: Well, what's happening most notably is oil is not flowing into the Gulf. This is a moment that we've been building up to for obviously 12 weeks. And the reason it's not is 'cause they've installed this new cap. The cap has three valves on it and they have gradually closed the valves. The third and final valve was closed at - just a little while ago. And it was just quite something to see that there was no oil coming out that pipe for a period of time.
SIEGEL: And when we say a cap, describe the shape or the size of this thing that's been put over the gushing well.
HARRIS: Well, the cap itself is something like 150,000 pounds. It has all sorts of stuff on the side of it. The main point of the cap, well, it has two points, one is to run this test that they're running right now.
This may not be a permanent condition. We may see oil back in the Gulf. But it - but the cap also has the ability to take oil out of pipes. It's a nicely sealed cap to the top of the well and they can run pipes from that cap to ships on the surface. And so, if this test fails and they say we have to open the valves again, they have the option of then - and they plan to capture the oil through these pipes, bring it up to the surface. That will take a number of days to accomplish but, you know, either way it appears as though we're seeing the beginning of the end here.
SIEGEL: But when you say the test, the testing, the test will take several days or...
HARRIS: The test will take several days, yes. The idea is to shut off the top of the well. And what happens is, since oil and gas is rising up through the well, what they're looking for is the pressure. They're measuring the pressure of that oil and gas. And if they close off the well and the oil and gas keeps flowing, the pressure should build up in that well. It can't flow out, so it's just building up some pressure up into a certain point.
If they're measuring the pressure and it turns out that the pressure is staying low, that means that the well must be leaking someplace far under the surface. This well is 13,000 feet long under the surface of the sea. And someplace under there, it would be leaking. At which point they would start to be concerned about, what is the shape of the well? And if they decide that the well is in too bad shape, that's why they would reopen the valves.
SIEGEL: But the risks here are first that this just might not work and they might have to replace the cap or that there could be a leak somewhere else. How would you assess the risk?
HARRIS: Well, the cap is - it's going to stay there. The cap is functioning perfectly fine. The question is what condition the well is in. If the well is leaking, then they have to open the valves again and they have to let the oil out again. But if it's not, they can just leave these valves closed and this is the end of the spill essentially for right now.
The cap will stay in place and they will go ahead and they will finish the relief well that will allow them to pour cement into the very bottom of this well and ultimately fill this well with cement and plug it off permanently. The cap is a temporary solution, but it should hold long enough to make the permanent solution permanent.
SIEGEL: And we're still tentative here. BP says the oil is not flowing anymore, whether that's permanent, we don't know, but it's the best news we've had in several weeks.
HARRIS: It certainly is. This test could last for a couple of days and at which point they could decide it's working, it's not working or anytime in between.
SIEGEL: Thank you, Richard.
HARRIS: My pleasure.
SIEGEL: That's NPR science correspondent Richard Harris.
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