Comments about technological history, system fractures, and human resilience from James R. Chiles, the author of Inviting Disaster: Lessons from the Edge of Technology (HarperBusiness 2001; paperback 2002) and The God Machine: From Boomerangs to Black Hawks, the Story of the Helicopter (Random House, 2007, paperback 2008)

Wednesday, April 27, 2011

Atlantis on STS-46: An alert crew saves the day

In honor of Endeavour's upcoming launch, here's a link to a fine time-lapse video of launch preparations for STS-131: raising the orbiter Discovery, mating it to the external tank and solid rockets, and rolling it out for launch.

While researching a piece on the redesigned solid rocket motor for Air&Space Magazine, I visited the Vertical Assembly Building during operations and had the chance to watch an overhead crane hoist a segment for stacking into a full solid rocket motor. Slow was the word.

Normally visitors aren't allowed into the VAB when the solid rocket booster sections are being moved. The reason is that solid fuel propellant acts like an explosive if dropped -- see this 1990 account of a fatality when a Titan 4 solid fuel booster hit the ground during a crane lift at Edwards AFB. Because my article was specifically about the booster, I got permission to watch the lift in the company of an escort. Movements of the booster segment were most amazingly slow ... much less than walking speed.

The Shuttle program has reached its 30th year and the last flight will be Atlantis, numbered STS-135, a cargo flight to the International Space Station. After that, it's off to the museums

The plans for Atlantis reminds me of one of that ship's earlier missions, STS-46. Within that mission, is a story of how an alert crew caught a potentially dangerous situation from causing damage. Disasters hardly ever come like a bolt from the blue: they develop from a combination of weak spots that join up over days, months, and even years.

The close call involved EURECA, short for European Retrievable Carrier satellite. It was like a truck for long-duration orbital experiments, to be retrieved by another shuttle later. Here's a photo of the Canada Arm lifting EURECA out of the payload bay.

So far, so good. The satellite took up a position 300 meters away while controllers at a command center in Germany ran through a series of checks. The crew waited several hours, then broke for dinner, except astronaut Andy Allen. He stood guard on the flight deck, the crew members all aware that having a powered satellite so close was a factor that needed watching.

It was a good thing that this guard was kept, as Atlantis passed into the night side of the Earth and the shuttle went into a communications blackout zone -- an area between relay stations.

Next, the shuttle's proximity radar set off a "range rate" alarm, indicating that EURECA was heading for the shuttle, later determined to be a closing speed of four to five feet per second. Unable to reach the satellite controllers in Germany, Allen fired the reaction control thrusters to get out of the way, though there was a risk the exhaust could damage the satellite's solar panels. The booms of these thrusters roused the other astronauts, who hustled up from dinner. "Where's the satellite?" they wanted to know. Allen couldn't say, other than it was so close the radar couldn't pick it up. The astronauts looked out the windows with flashlights.

The prompt action had avoided a collision. After conversation with Earth was possible, the crew learned that a glitch in Germany had fired the satellite's thrusters in such a way to send it hustling toward Atlantis.

Afterward, an astronaut took this wonderful photo of EURECA, now safely back in its station-keeping position, seemingly scooting among the clouds east of Cape Canaveral (the coastline visible at bottom).

This photo shows vividly how clouds come in many flavors, and at many altitudes.

 For more such photos, see JSC's image archive. Great stuff!

Saturday, April 23, 2011

Fukushima Dai-ichi Unit 1: Risky piece inside a wicked problem

Tepco has released a set of flow charts and simple diagrams called the Roadmap, which lay out a broad summary of its plan to get control of Fukushima Dai-ichi sometime in 2011.

In tackling this wicked problem Tepco plans to fill the reactor pressure vessel (RPV) of Unit 1 with enough water to cover the fuel assembly fully. It's considered a priority because the core of Unit 1 is in the worst shape of all the Dai-ichi reactors, with more than two-thirds of its fuel rods damaged.

See this WSJ article on an engineering dispute about whether the damaged structure of Unit 1 is strong enough to take the full weight of water planned.

(Also, as I mentioned in this post, Unit 1 is unique because the pressure has steadily been rising in its RPV. It now registers 1.12 megapascals -- that's 162 pounds per square inch -- on Pressure Gauge B, which is five times the reading in mid-March and much higher than the pressure in the other damaged reactors. It doesn't mean Unit 1's RPV is in a dangerous state but it ranks as an anomaly.)
Since a major roadblock to human intervention is radioactive water in the basements and nothing much can be done until the source is cut off and water is pumped out, Tepco's hope is that repairs in the near future can stop this coolant from dumping into the basement; Tepco wants to keep the reactor coolant in a closed circuit, with heat transferred to the air rather than was water going into basements or the ocean.

Meanwhile, Tepco has been posting still and video shots on this website. The pace of added material has slowed since April 20 but there is good material, lately from cameras on board the T-Hawk ducted-fan drone and ground robots.

Putting Unit 1 in the limelight requires separating it from the others. First, here's the big picture, from the Wikipedia website on the Fukushima crisis. Before the damage they looked like this, from above:
From, an airplane view:
From Wikipedia, the post-explosion view. Unit 1 is the boxlike structure on the far right of the four shown in Reactor Row.
It can be hard to keep them straight in news clips -- I've seen captions that confuse Unit 4 with Unit 1 -- so it helps to remember that Unit 1 has a different appearance from the rest. From most angles,  the lower walls of Unit 1 appear to be mostly intact while the upper walls are missing, leaving only the structural steel showing.

By contrast, Unit 2 still has its walls, and Units 3 and 4 look mostly like skeletons.

Next is a T-Hawk drone-cam view of Unit 1's roof. Presumably the explosion wrecked the deck's trusswork and wall connections and it collapsed onto the upper levels of the massive concrete structure. The roof will be one of many complications in dealing with the spent fuel pool. I'm not sure what the big brown cylinder is on the right -- maybe a heat exchanger?
Here's a clearer view of Unit 1, with Unit 2 on the left:
Here's the control room of Unit 1. Something,  either the earthquake or a later blast, caused all the panels in the false ceiling to come loose. The control room is in a location other than the reactor building.

Saturday, April 16, 2011

Fukushima's Sea-Salt Problem, Continued

In previous blogs I fretted about the use of seawater to cool Fukushima, because these are boiling water reactors. As hundreds of tons of seawater boiled away, a heavy load of minerals remained around the core and below. While most experts agree seawater injection via the feedwater lines was the right thing to do given the alternative (no cooling at all, and prompt meltdown), there is good reason to believe that salt buildup is blocking effective cooling of the fuel assembly in Unit 1 and perhaps the others. 

Unit 1 is what I've been following, because it's an old model with fewer protections, because the upper containment walls and roof blew off, and because the main trend of pressure readings in the reactor pressure vessel (RPV) has been steadily upward for three weeks, to nearly one megapascal. That's still well below the manufacturer's pressure rating, but does make one wonder what it means, and why the rising trend hasn't leveled off.

Late in March NRC staff considered the scant evidence, ran models, and advised the Japanese that salt deposits in Unit 1 most likely were jammed into the lowest part of the reactor pressure vessel (RPV) up to the bottom of the fuel assembly. That's a lot of salt.
There is some hope that the tonnage of salt could be less now, given that Tepco began injecting freshwater on March 25. And it makes sense that fresh water could dissolve salt and carry it out in solution.

Tepco could estimate the salt-removal rate by sampling the heated water for mineral content as it leaves the RPV. Are they? Who knows! Very little operational data is on line.

The pressure rise in Unit 1's RPV could be a good thing, or a bad thing. Maybe it hints that Tepco is more confident of its improvised plumbing now. But it would be worrisome if it means that a chunk of mineral is blocking water flow at an outlet and the only way Tepco has been able to maintain a critical flow rate (called the minimum debris retention injection rate, or MDRIR) has been to dial up the pressure. 

MDRIR sounds like just another metric in a long list but it means "enough emergency cooling water to keep the wrecked fuel -- the debris -- from melting through the reactor pressure vessel." So maintaining flow at or above the MDRIR does matter. The latest official guesstimate is that crumbled fuel has gathered at the bottom of Unit 1's RPV, but has not melted the steel wall and escaped into the primary containment. Pressure readings appear to support that conclusion.

Getting the salt out from the bottom of the RPV will depend on jet pumps and recirculation pumps that can force water to the bottom of the vessel.

The emergency cooling water has been entering the middle part of the vessel via the feedwater lines. Therefore the bottom section, where wrecked portions of fuel assembly have piled up, isn't being cooled well. ( But there's less decay heat now, so that's one bit of good news.)

Restoration of proper cooling will depend on successful completion of some very difficult tasks in and around the bottom of the semi-wrecked and highly radioactive building: replacing seals, repairing motors, calibrating instruments and transducers, checking for cracked pipes and hangers, and freeing up stuck valves

Notice how congested it is in the lower reaches, below compartments of reinforced concrete that prevent work by overhead cranes.
No workers can carry out such heavy-duty repairs until highly radioactive water is removed and surfaces are cleaned. So until flow is restored to the bottom part of the RPV through the recirculation circuit, Unit 1 is going to continue suffering from blocked arteries.

Tuesday, April 12, 2011

Tokyo, hoping for the best

NPR ran a piece last week about efforts in Tokyo to cut power consumption. One spot highlighted was Shibuya shopping district, northwest of Tokyo Bay. 

My sons and I spent a week in Tokyo and Kyoto last August, and passed through Shibuya several times, making sure to catch it at least once by night, when it was ablaze with neon and acres of LED screens

It's a major meet-up spot, and thousands of Japanese young people were milling about, phones in hand, hunting for friends. It's close to the Shinjuku train station, where commuters now walk through the vast tunnel system in dimmed lighting; at night they now emerge to a much darker landscape. 

The Shinjuku area by daylight:
The next day I took a picture of another electricity-drawing entertainment powerhouse. It's a multi-level arcade called Joypolis, in a shopping mall called Aqua City, on the manmade Odaiba Island. Here's the entrance:
We checked out the Joypolis attraction called Prison Break: the guide spoke in Japanese, and Son No. 3 translated. 
Now all amusement parks are on reduced hours and even days due to power shortages.  

Shibuya and Aqua City are faves on the Western itinerary, but how many visitors make it out to Yomiuri Land? It's in the western suburbs, and took us a couple of hours to reach via subway -- because we went to the wrong stop first. 

It's an amusement park near a training ground for the Yomiuri Giants baseball team. The roller coaster track is laid across several hills. The snack foods were very good, or maybe we were just hungry.
Tokyo lies on the Kanto Plain, without a lot of hills -- hence recent concerns on how the low-lying areas near the harbor and rivers will fare if a nearby temblor launches a tsunami.

We took this photo on the way to Odaiba Island. It's not set up to fight back the sea.
After Tokyo, we hopped on the Shinkanzen down the coast to the southwest, to Kyoto and Hiroshima. Very hospitable country, great for tourists. I'd go back tomorrow!

It struck me while riding the bullet train that there's little unused land anywhere near the populated areas. It's all taken up by buildings, roads, homes, cemeteries, factories, rice paddies, or forest preserves. So there's much discussion about where to put 100 million tons of so of earthquake and tsunami debris. After recycling and waste-to-energy combustion, I'm guessing some of it will be used as fill to elevate low areas.

Thursday, April 7, 2011

More on Fukushima's emergency-generator problems

The Japanese newspaper Asahi Shimbun has provided new details on what happened with the generators at Fukushima Dai-Ichi. I've been looking for more about this problem, said to be the immediate cause of what now looks like a true meltdown in Unit 1 (fuel assembly melting through the steel walls of the RPV, and gathering somewhere at the lower reaches of the primary containment.) 

The original story goes like this: "The tsunami wave was so high that it breached the seawall and flooded the basement where the emergency diesel generators were located. The emergency batteries ran the pumps for eight hours. When they expired, the reactors began overheating because the decay heat couldn't be removed from the fuel assemblies." 

Given eight hours of notice, and knowledge of how serious the problem would be, why couldn't emergency diesel generators be flown in? Powerful, skid-mounted generators are all over the place, used by companies in emergencies and by motion picture productions. Surely the world's fourth biggest electric company could round up portable generators on short notice. 

I've suspected there was more to the story. The Asahi Shimbun piece suggests that Tepco didn't bring in generators because there were more problems than flooded generators and their diesel fuel supplies. It compares this plant to later complexes, where generators and seawater pumps were protected inside the more stoutly-built reactor buildings. Referring to the Dai-Ichi complex as plant No. 1, the article says the flooding affected not only the generators, but pumps that brought in seawater for cooling:

“The tsunami rendered inoperable all of the No. 1 plant's pumps, which were also not located within a sealed structure.... Referring to the possibility of installing the seawater pumps inside buildings, the former TEPCO engineer said, "It would have been a major project because various pipes are laid out under the pumps, and so all of that would also have had to be moved."

The basement of which building? Most likely the turbine building. See this link on PhysicsForums, where a participant went through German documents to pinpoint the emergency generators' most likely location.

Sunday, April 3, 2011

Southwest B737-300: Rapid descent to Yuma

Quick post on the news item Friday about Southwest Flight 812, Phoenix to Sacramento, which had to make an unscheduled landing after a section of skin roughly 3 x 4 foot in size blew out from the top of its fuselage. One passenger said the location was around Rows 12-13. Tail number is N632SW. It was manufactured in 1996. Over 930 model 737-300s are flying worldwide 

For pilot enthusiasts, here's a link to what appears to be a Boeing manual that includes a section on rapid descents. See material starting on PDF page 209: advice is to limit airspeeds and maneuvering loads if structural damage is suspected (or confirmed, given a big hole in the cabin).

The discussions on and, a pilots' forum, are worth reading. It is disappointing to read about several years of maintenance shortcuts by Southwest management, and clashes with regulators. 

A NTSB link to a skin blowout incident on an Aloha Airlines 737 is here. A Time article on that one is here. It was fatal to one flight attendant who was sucked out of the cabin. (But the Aloha plane didn't crash as in a previous cabin-skin failure, of a Far Eastern Air Transport 737-200 in 1981.) For more context, see this Airsafe list of 737 crashes

That said, the 737 is a workhorse and has accumulated an impressive safety record. But apparently some of its operators can do better. Inspections and prompt repairs, done by the book, are key. 

I'm told that all aircraft have cracks in them somewhere, if one looks closely enough. While writing my helicopter book I was surprised to be shown how a helicopter company manages tiny but visible cracks in rotor blades on executive helicopters, found during periodic inspections. These blades are so expensive that cracks once detected, if well below a risk threshold, are monitored and managed, rather than replacing the entire blade.

Back to airliners. One catastrophic risk in fuselage-blowout cases, even those in which the lower section of the aircraft remains structurally sound, is collateral damage to wiring harnesses, control cables, or hydraulics that happen to be routed nearby. This is not a small matter.

You can see a wiring bundle at the center of this widely distributed photo from the Flight 812 incident. Normally it's concealed behind a ceiling panel but was exposed by the blowout.

Friday, April 1, 2011

Rooftop Heli-Commuting: Back in the news

Noting this piece in the LATimes, "Helicopter Battle Kicks Up Dust in West Hollywood," about the Sofitel Hotel's request to change its emergency-only landing pad into a limited-use helicopter parking lot, called a helistop. According to the article, the driving force is producer Kevin Kavanaugh, who first set up the ruckus by using the hotel roof for commuting to and from his house in Malibu. His studio is near the hotel. 

Some nearby residents are mobilizing against it. Friends of his in the city and county level have written letters of support, but CalTrans makes the final call.

One reason rooftop commuting has languished in this country is a chain of events that ended with a tragedy atop New York’s Pan Am Building. The world's hottest spot for rooftop helicopter commuting by the wealthy is faraway Sao Paulo, Brazil.

Meantime, excerpted from my book The God Machine, here's some early rooftop-helicopter-history. 

In 1926 Thomas Edison gave an interview about aviation that touched optimistically on the subject of helicopters and cities. “It does not require any very vivid imagination to help us realize that when the helicopter comes into being, roofs of large buildings in our cities immediately will become very valuable parts of such structures,” Edison said. “Certain new varieties of disaster will then develop, but is useless to foretell these now. We shall know all about them when they come. But they will not keep us out of the air transport machines.”
The space that eventually became New York's Pan Am Building (now MetLife) started out as a concept for an 80-story tower that would take the place of Grand Central Terminal. In 1958 it was condensed to stand at the back of the terminal rather than replace it. When completed in 1963 at 58 floors, the building blocked the view down Park Avenue and most architectural critics didn’t like its plain, beveled-box design. Still, at 2.4 million square feet it was for a time the world’s biggest office building.

It would have another distinction. In September 1960 the president of New York Airways saw a notice about the building plans and wrote Juan T. Trippe, chairman of Pan American World Airways, proposing a heliport and offering to lease it: A heliport, he said, would “be of inestimable value to the community.” Pan Am agreed that the opportunity should not be missed and began moving down the paperwork trail. 

Four years later the plan almost came undone when the commander of the NYPD’s aviation unit, William McCarthy, recommended in a confidential report that the city hold off on approving the zoning change for the heliport. McCarthy, who was on the edge of retirement, said the heliport was not a top priority for the city because riverside heliports were available just a mile away to the east and west. Opponents found out and published his report but the zoning change went ahead anyway. Test flights began in May 1964, followed by promotional trips for VIPs to the New York World’s Fair. The heliport opened for business on December 21, 1965.

The historic day began with a lunch at the Waldorf-Astoria’s Starlight Roof and a speech from Juan Trippe. Also present: Francis Cardinal Spellman, the president of New York Airways, the operator; the president-elect of the city council, and the president of U.S. Steel. “Urban helicopter travel is here to stay,” said Trippe. 

The helicopter to be used was a civilian version of the military’s CH-46 Sea Knight, which seated two dozen. The airline planned to move over 4,000 people every week. 

The guests adjourned by limousine to the Pan Am Building for the cutting of a red ribbon held by two helicopter hostesses. Vice President Hubert Humphrey telephoned to turn on the heliport lights by “remote control” and to offer a message. “The establishment of helicopter service between city centers and outlying airports can do much to ease urban traffic congestion,” he said. “I hope other major cities will soon follow New York’s example.” Regular service began that evening.

To air-minded futurists, rooftop travel was overdue and a vindication for dozens of Sunday newspaper supplements and magazine covers that had promoted such opportunities. It had been eighteen years since a helicopter first set foot on Manhattan, at the request of a department store. A few other cities had downtown heliports at this time, but only on the Pan Am roof did the reality approach the original vision ... until the disaster of 1977: a subject for a later post.

I rode on this helicopter as a kid, with my family, while it was running tourists to the World's Fair.  One way to see it in operation is to watch the opening minutes of Coogan's Bluff: Clint Eastwood's character arrives in the Big Apple by touching down at the Pan Am heliport. (Sidebar: The Port Authority of NY and NJ is the only other organization besides the Pan Am Building owners that had an operating rooftop heliport for civilian travel on Manhattan Island, in this case, for employees. Helicopters touched down atop its building at 111 - Eighth Avenue. That giant building was in the news last year, when Google paid $1.9 billion for a data and cable-routing center)