I’ve been following the nuclear disaster in Japan over the past couple of weeks, and have done some more research into Chernobyl. Some things have really stood out and made an impression on me, so I’m taking another look at my last posting, which offered a potential solution to the problem of containment at a failed nuclear power site.
One of the most compelling things to me is the extent of damage that occurred at Chernobyl. This happened in 1986, and while the Chernobyl disaster remains the worst nuclear accident on record, it seems largely absent from the minds of most people. Chernobyl remains an incredibly dangerous and toxic site, and is far from being resolved, or reclaimed, or made safe in any way.
Here is a decent summary of events that transpired in April 1986 at Chernobyl. The entire accident was actually due to a test (or experiment) which had been scheduled quite in advance. This planned experiment was to do an emergency shutdown of the nuclear reactor, and to see if the angular momentum (“spinning power”) of the generator was enough power to provide electricity for the pumps to continue cooling the reactor, even with the reactor shutdown.
“Even when not actively generating power, nuclear power reactors require cooling, typically provided by coolant flow, to remove decay heat. Pressurized water reactors use water flow at high pressure to remove waste heat. Following an emergency shutdown (scram), the core still generates a significant amount of residual heat, which is initially about seven percent of the total thermal output of the plant. If not removed by coolant systems, the heat could lead to core damage.” (Taken from Wikipedia).
During this experiment the core overheated, resulting in several explosions. These explosions were extremely dangerous because the Chernobyl reactor does not have a containment structure surrounding the reactor vessel. Thus any radioactive material could escape to the outside, which is precisely what happened. At the Fukushima Daiichi nuclear plant, the core overheated because of pump failure due to the earthquake and resulting tsunami. The Fukushima Daiichi plant does not have a containment structure around the reactor vessel either: so radioactive material could escape to the outside, which is also precisely what happened, and is still happening.
Following the disaster at Chernobyl, a decision was made to entomb the stricken reactor in what has been called a “sarcophagus.” This structure was haphazardly made, and many engineers gave their lives in providing this hastily built initial containment structure. “Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and health care costs of the Chernobyl accident. Thirty one deaths are directly attributed to the accident, all among the reactor staff and emergency workers. Estimates of the number of deaths potentially resulting from the accident vary enormously; the World Health Organization (WHO) suggest it could reach 4,000 while a Greenpeace report puts this figure at 200,000 or more. The 2011 UNSCEAR report places the total deaths from radiation to date at 64”. (from Wikipedia)
Currently, the sarcophagus at Chernobyl is in bad shape. It is crumbling, sinking, and is not expected to fulfill its 30-year life expectancy which engineers planned for when the sarcophagus was built. Currently there are holes in it large enough to drive a car through!
The plans for covering the sarcophagus were briefly discussed in my last entry. “The Chernobyl Shelter Fund was established in 1997 at the Denver 23rd G8 summit to finance the Shelter Implementation Plan (SIP). The plan calls for transforming the site into an ecologically safe condition by means of stabilization of the sarcophagus followed by construction of a New Safe Confinement (NSC). While the original cost estimate for the SIP was US$768 million, the 2006 estimate was $1.2 billion. The SIP is being managed by a consortium of Bechtel, Battelle, and Electricité de France, and conceptual design for the NSC consists of a movable arch, constructed away from the shelter to avoid high radiation, to be slid over the sarcophagus. The NSC is expected to be completed in 2013, and will be the largest movable structure ever built”.
Dimensions:
• Span: 270 m (886 ft)
• Height: 100 m (330 ft)
• Length: 150 m (492 ft)
So the shelter to cover Chernobyl will be the largest moveable man-made structure ever built, all to avoid radiation: which would be present if the structure were built directly over the sarcophagus. This is a job I would not want to do! Bring in the best robots we have!
The current condition of the Chernobyl sarcophagus is so poor, and in such need of repair or replacement, that Russian scientist Chernosenko is quoted as saying: “The next Chernobyl will be Chernobyl itself.”
There are 216 tons of radioactive uranium and plutonium waste inside the Chernobyl sarcophagus. There are 740,000 cubic meters of lethally contaminated debris (ten times more than previously thought!). This includes 30 tons of highly contaminated dust, 16 tons of uranium and plutonium and 200 tons of radioactive lava. Rainwater can enter the sarcophagus, which has created a radioactive soup inside. This place is a bad mess. Robots were used to assemble the sarcophagus, which meant that joints could not be welded, and nuts & bolts could not be used. The state of robotics today has hopefully improved enough that they will be more effective in building a containment structure.
While the nuclear disaster in Japan was not as bad as Chernobyl, there are many lessons to be learned from looking at the Chernobyl experience. First, the Japanese disaster can be expected to continue for decades to come. Second, a containment structure is important (did this lesson really need to be re-learned?) Third, an effective method for utilizing robots to assemble a containment structure is absolutely critical. The modular concrete construction system I’ve been describing on this blog is one such method.
In my experience, certain corporate cultures suffer from arrogance about their own technology. This is well known to entrepreneurial engineers, and has become known as the “NIH syndrome.” NIH means Not Invented Here, and is a put-down to anyone else’s technology, idea or approach. I fervently hope that anyone reading this blog can see past their own corporate culture, e.g.: Westinghouse and General Electric, two big players in the nuclear industry which tend to suffer from the NIH Syndrome.
One of the most compelling things to me is the extent of damage that occurred at Chernobyl. This happened in 1986, and while the Chernobyl disaster remains the worst nuclear accident on record, it seems largely absent from the minds of most people. Chernobyl remains an incredibly dangerous and toxic site, and is far from being resolved, or reclaimed, or made safe in any way.
Here is a decent summary of events that transpired in April 1986 at Chernobyl. The entire accident was actually due to a test (or experiment) which had been scheduled quite in advance. This planned experiment was to do an emergency shutdown of the nuclear reactor, and to see if the angular momentum (“spinning power”) of the generator was enough power to provide electricity for the pumps to continue cooling the reactor, even with the reactor shutdown.
“Even when not actively generating power, nuclear power reactors require cooling, typically provided by coolant flow, to remove decay heat. Pressurized water reactors use water flow at high pressure to remove waste heat. Following an emergency shutdown (scram), the core still generates a significant amount of residual heat, which is initially about seven percent of the total thermal output of the plant. If not removed by coolant systems, the heat could lead to core damage.” (Taken from Wikipedia).
During this experiment the core overheated, resulting in several explosions. These explosions were extremely dangerous because the Chernobyl reactor does not have a containment structure surrounding the reactor vessel. Thus any radioactive material could escape to the outside, which is precisely what happened. At the Fukushima Daiichi nuclear plant, the core overheated because of pump failure due to the earthquake and resulting tsunami. The Fukushima Daiichi plant does not have a containment structure around the reactor vessel either: so radioactive material could escape to the outside, which is also precisely what happened, and is still happening.
Following the disaster at Chernobyl, a decision was made to entomb the stricken reactor in what has been called a “sarcophagus.” This structure was haphazardly made, and many engineers gave their lives in providing this hastily built initial containment structure. “Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and health care costs of the Chernobyl accident. Thirty one deaths are directly attributed to the accident, all among the reactor staff and emergency workers. Estimates of the number of deaths potentially resulting from the accident vary enormously; the World Health Organization (WHO) suggest it could reach 4,000 while a Greenpeace report puts this figure at 200,000 or more. The 2011 UNSCEAR report places the total deaths from radiation to date at 64”. (from Wikipedia)
Currently, the sarcophagus at Chernobyl is in bad shape. It is crumbling, sinking, and is not expected to fulfill its 30-year life expectancy which engineers planned for when the sarcophagus was built. Currently there are holes in it large enough to drive a car through!
The plans for covering the sarcophagus were briefly discussed in my last entry. “The Chernobyl Shelter Fund was established in 1997 at the Denver 23rd G8 summit to finance the Shelter Implementation Plan (SIP). The plan calls for transforming the site into an ecologically safe condition by means of stabilization of the sarcophagus followed by construction of a New Safe Confinement (NSC). While the original cost estimate for the SIP was US$768 million, the 2006 estimate was $1.2 billion. The SIP is being managed by a consortium of Bechtel, Battelle, and Electricité de France, and conceptual design for the NSC consists of a movable arch, constructed away from the shelter to avoid high radiation, to be slid over the sarcophagus. The NSC is expected to be completed in 2013, and will be the largest movable structure ever built”.
Dimensions:
• Span: 270 m (886 ft)
• Height: 100 m (330 ft)
• Length: 150 m (492 ft)
So the shelter to cover Chernobyl will be the largest moveable man-made structure ever built, all to avoid radiation: which would be present if the structure were built directly over the sarcophagus. This is a job I would not want to do! Bring in the best robots we have!
The current condition of the Chernobyl sarcophagus is so poor, and in such need of repair or replacement, that Russian scientist Chernosenko is quoted as saying: “The next Chernobyl will be Chernobyl itself.”
There are 216 tons of radioactive uranium and plutonium waste inside the Chernobyl sarcophagus. There are 740,000 cubic meters of lethally contaminated debris (ten times more than previously thought!). This includes 30 tons of highly contaminated dust, 16 tons of uranium and plutonium and 200 tons of radioactive lava. Rainwater can enter the sarcophagus, which has created a radioactive soup inside. This place is a bad mess. Robots were used to assemble the sarcophagus, which meant that joints could not be welded, and nuts & bolts could not be used. The state of robotics today has hopefully improved enough that they will be more effective in building a containment structure.
While the nuclear disaster in Japan was not as bad as Chernobyl, there are many lessons to be learned from looking at the Chernobyl experience. First, the Japanese disaster can be expected to continue for decades to come. Second, a containment structure is important (did this lesson really need to be re-learned?) Third, an effective method for utilizing robots to assemble a containment structure is absolutely critical. The modular concrete construction system I’ve been describing on this blog is one such method.
In my experience, certain corporate cultures suffer from arrogance about their own technology. This is well known to entrepreneurial engineers, and has become known as the “NIH syndrome.” NIH means Not Invented Here, and is a put-down to anyone else’s technology, idea or approach. I fervently hope that anyone reading this blog can see past their own corporate culture, e.g.: Westinghouse and General Electric, two big players in the nuclear industry which tend to suffer from the NIH Syndrome.
No comments:
Post a Comment