[Marxism] N.R.C. Lowers Estimate of How Many Would Die in Meltdown

Bonnie Weinstein giobon at comcast.net
Sat Jul 30 11:45:00 MDT 2011


N.R.C. Lowers Estimate of How Many Would Die in Meltdown
[Or, “Don’t worry. Be happy. Not too many of us will die”….Bonnie  
Weinstein]
“Big releases of radioactive material would not be immediate, and  
people within a 10-mile radius would have enough time to evacuate,  
the study found. The chance of a death from acute radiation exposure  
within 10 miles is therefore near zero, the study projects, although  
some people would receive doses high enough to cause fatal cancers in  
decades to come. … One person in every 4,348 living within 10 miles  
would be expected to develop a ‘latent cancer’ as a result of  
radiation exposure, compared with one in 167 in previous estimates.”
By MATTHEW L. WALD
July 29, 2011
http://www.nytimes.com/2011/07/30/science/earth/30radiation.html?hp

ROCKVILLE, Md. — The Nuclear Regulatory Commission is approaching  
completion of an ambitious study that concludes that a meltdown at a  
typical American reactor would lead to far fewer deaths than  
previously assumed.

The conclusion, to be published in April after six years of work, is  
based largely on a radical revision of projections of how much and  
how quickly cesium 137, a radioactive material that is created when  
uranium is split, could escape from a nuclear plant after a core  
meltdown. In past studies, researchers estimated that 60 percent of a  
reactor core’s cesium inventory could escape; the new estimate is  
only 1 to 2 percent.

A draft version of the report was provided to The New York Times by  
the Union of Concerned Scientists, a nuclear watchdog group that has  
long been critical of the commission’s risk assessments and obtained  
it through a Freedom of Information Act request. Since the recent  
triple meltdown at the Fukushima Daiichi nuclear plant in Japan, such  
groups have been arguing that the commission urgently needs to  
tighten safeguards for new and aging plants in the United States.

The report is a synthesis of 20 years of computer studies and  
engineering analyses, stated in complex mathematical terms. In  
essence, it states that if a prolonged loss of electric power caused  
a typical American reactor core to melt down, the great bulk of the  
radioactive material released would remain inside the building even  
when the reactor’s containment shell was breached.

Big releases of radioactive material would not be immediate, and  
people within a 10-mile radius would have enough time to evacuate,  
the study found. The chance of a death from acute radiation exposure  
within 10 miles is therefore near zero, the study projects, although  
some people would receive doses high enough to cause fatal cancers in  
decades to come.

One person in every 4,348 living within 10 miles would be expected to  
develop a “latent cancer” as a result of radiation exposure, compared  
with one in 167 in previous estimates.

“Accidents progress more slowly, in some cases much more slowly, than  
previously assumed,” Charles G. Tinkler, a senior adviser for  
research on severe accidents and one of the study’s authors, said in  
an interview at a commission office building here. “Releases are  
smaller, and in some cases much smaller, of certain key radioactive  
materials.”

The N.R.C. did not intend to release the report until next spring and  
said its conclusions were still being adjusted after a peer review.

The health effects of a catastrophic meltdown were hypothetical until  
the 1979 accident at Three Mile Island. That destroyed a billion- 
dollar reactor but caused no apparent physical harm to nearby  
residents, immediately or over time. Debate has persisted over  
whether the United States skirted a disaster or whether that accident  
was about as bad as it could get.

Edwin Lyman, a nuclear physicist with the Union of Concerned  
Scientists, contends that the nuclear commission has consistently  
painted an overly rosy picture and that its latest study does as  
well. He noted that the study assumed a successful evacuation of 99.5  
percent of the people within 10 miles, for example. The report also  
assumes “average” weather conditions, he noted.

But if a rainstorm were under way during a release of radioactive  
materials, he said, it could wash contaminants out of the air into a  
small area, producing a high dose there.

Jennifer L. Uhle, the deputy director of the commission’s office of  
nuclear regulatory research, said the report was intended to present  
the “best estimate” and not the worst case.

Dr. Lyman said the earlier estimate was of a different accident, a  
major pipe break. The new study considered that accident too unlikely  
to analyze.

Dr. Lyman suggested that in projections of fatal cancer cases, the  
focus should be on people who live within 50 miles. The average  
population within 10 miles of an American nuclear plant is 62,000;  
within 50 miles, it is about five million.

The commission’s old projection of eventual cancer deaths was one for  
every 2,128 people exposed within 50 miles; the new study projects  
one cancer death for every 6,250 people exposed, which still comes to  
hundreds of cancer deaths within the 50-mile circle, in addition to  
the hundreds of thousands who would be expected to die of cancer from  
other causes.

Dr. Lyman countered that when dealing with estimates based on so many  
variables — including more than 100 reactors of different designs and  
vintage, in areas with disparate population densities — a difference  
of a factor of three is not important. In his view, the study  
reconfirms that reactors pose serious risks.

The commission’s shift in thinking about how much radioactive cesium  
137 would escape after a core meltdown is based on a conclusion that  
most of it would either dissolve in water that stays put or adhere to  
surfaces within the plant. The authors said previous analyses had  
made “conservative assumptions” that most of the cesium and other  
materials would escape. But laboratory studies and computer modeling  
have not borne out that hypothesis, they said.

Commission experts have said that a total blackout would be extremely  
rare at an American plant and that backup generators and other  
machinery would fill the breach until grid power was restored.  
Nonetheless, the study focused on what would happen in the event of a  
nuclear station blackout, meaning a complete loss of power from the  
grid and from backup diesel generators, and then an exhaustion of  
batteries that supply power, leading to a meltdown. That is what  
happened at Fukushima.

The study focused on two common reactor types in this country:  
boiling-water reactors at the Peach Bottom Atomic Power Station in  
Pennsylvania, similar to those at Fukushima, and pressurized-water  
reactors at the Surry Power Station in Virginia.

The study gives a highly detailed prediction of which equipment would  
stop operating; what temperatures, steam pressures and flows of water  
and steam would result; and where and when leaks would begin after a  
meltdown.

It concluded that Peach Bottom would not release enough radioactive  
material to kill anyone immediately, although it could increase the  
rate of cancer deaths over future decades. At Surry, the probability  
was so low and the number of people living within 10 miles so small  
that the death toll would be a fraction of a person.

The report was prepared by staff members of the Nuclear Regulatory  
Commission and Sandia National Laboratories, a Department of Energy  
lab. Beyond the revisions to be made as a result of the peer review,  
the report could undergo further changes after public comments are  
received next year.

Once completed, it might be used by the commission when it analyzes  
proposed safety improvements in terms of costs and benefits, or  
decides where reactors should be located.

“Once we think we know what the best estimate is, we think we can  
start thinking about applications,” said Jason H. Schaperow, a senior  
reactor systems engineer and one of the authors.



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