MIDDLEBURY-The General Electric-designed boiling water reactor (BWR) at the Vermont Yankee Nuclear Power Plant in Vernon, Vt., is similar to-although not exactly like-the malfunctioning reactors at the Fukishima No. 1 atomic-power station in Japan. The reactors are operated by the Tokyo Electric Power Company.
As a direct result of Japan's post-earthquake nuclear woes, Vermont Yankee's license extension request was put on hold by the U.S. Nuclear Regulatory Commission (NRC)March 16. Several other nuclear plant license renewal requests, in other states, have also been placed on hold by the NRC.
Vermont Gov. Peter Shumlin has opposed keeping the state's sole nuclear plant open; he made it part of his 2010 campaign platform. The plant supplies nearly one-third of Vermont's electricity. A new mix of imported hydroelectric, fossil fuel and homegrown alternative energy sources will be needed to replace Vermont Yankee's electricity if the plant closes next year, which now appears likely.
Like Vermont Yankee, all six Fukushima BWR reactors were designed by General Electric. But in Japan, Hitachi and Toshiba corporations were also involved.
The coastal atomic station was seriously damaged March 11 by a Richter-scale 9.0 earthquake. The quake hit Japan with both an extensive tidal wave and ground tremors. It released the equivalent energy of 474 megatons of TNT.
What is Vermont's history of earthquakes and could Vermont Yankee experience a Japanese-like earthquake-triggered meltdown?
According to an extensive earthquake hazard study conducted for the Vermont Emergency Management Agency in 1995, "The documented earthquake history of Vermont is only a few hundred years long, and it becomes progressively more incomplete as one goes backward in time."
However, it is unlikely that an earthquake on the scale seen in Japan has ever occurred in Vermont in human memory. There are certainly no known French or Native American accounts of large earthquakes in our region, dating back to the 1600s.
The largest earthquake recorded in Vermont, was the April 20, 2002, event - it registered somewhere between 5.0 and 5.3 on the Richter scale at AuSable, N.Y. Several aftershocks were felt. This quake released the same amount of energy as the atomic bomb dropped on Nagasaki in 1945 - 21,000 kilotons of TNT or about 75 million sticks of dynamite.
The 2002 quake was felt in most of western Vermont with some damage to roads and structures, reported in New York.
The next greatest events to rock the region was the July 6, 1943, earthquake near Swanton, and the April 10, 1962, event near Middlebury - both had magnitude 4.1, each with the yield of a modern, bunker-buster nuclear weapon.
An earthquake of magnitude 4.0 had an epicenter at Brandon on March 31, 1953, and the April 24, 1957 event at St. Johnsbury had among the highest intensity ever centered in Vermont.
Pro-nuclear power advocate and Yes Vermont Yankee blogger Willem Post, of Quechee, said Vermont Yankee's containment structure is safe and engineered to withstand earthquakes up to magnitude 6.5 (84.4 kilotons of energy).
Post said that he worries more about the possible closing of Vermont Yankee rather than of Vermont earthquakes.
"There was a major winter storm that swept through Vermont a few weeks ago," he said. "There is a wind turbine a few miles away from me; it was frozen solid and nearby solar panels were covered by ice and snow. Even the neighbor's woodpile was a frozen mass. Vermont Yankee was humming along - snow and ice be damned.
"When I throw the switch I get electricity. My lights, heat, refrigerator, and range are all working. My family is warm and fed, safe from the winter storm outside. All because of reliable electricity. Any politician who threatens that reliability should be held accountable," Post added.
Vermont State Geologist Laurence Becker, who is closely involved with the Vermont Emergency Management agency, said there have been several studies about Vermont Yankee and earthquakes dating back to the late 1960s.
Becker said Vermont quakes do not have the same high magnitude as the Japan quake because the state is located far from a plate boundary.
"As we saw in Japan, plate boundaries are prone to high energy events," Becker said. "We are inside a plate. Our nearest plate end is in the middle of the Atlantic Ocean. I was just with FEMA in Washington, D.C. We talked about the Japanese earthquake. I learned that a FEMA SAR (search and rescue)team was sent to Japan. The concern now was whether the FEMA people had to be decontaminated upon their return to the U.S."
Becker said there will be a lot of discussion about Vermont Yankee and earthquakes in the coming weeks and months.
"Well, I just returned from Washington," he said, "and I will be writing a memorandum to our state emergency management people about earthquakes here. I don't have details at the moment, but it is an ongoing discussion."
According to the NRC, Vermont Yankee was designed to withstand a magnitude 6.5 earthquake which is 20 times greater than the strongest earthquake ever recorded in this region.
State Geologist Becker noted that Vermont Yankee's above-ground, dry cask nuclear waste storage can withstand a 6.39 earthquake.
Like other nukes in the U.S., Vermont Yankee stores its nuclear waste on site in concrete casks above ground. Billions of dollars was spent on the shuttered Yucca Mountain storage site in Nevada; the facility has been held up for years due to local politics, litigation, and earthquake-fault concerns.
Post said he isn't worried about a Japan-style meltdown at the Vermont Yankee Nuclear Power Station in Vernon.
"Common power failures and less than 500-year floods are of no consequence to Vermont Yankee," Post said. "That is, as long as it has survivable and adequate emergency power systems which the NRC states it has."
The nuclear debate
Anti-nuclear Vermont State Sen. Dick McCormack (D,Windsor County)doesn't have a lot of faith in Vermont Yankee. He disagrees with Post's assessment of Vermont Yankee's durability.
"If the magnitude of the earthquake and tsunami were not what caused the meltdown in Japan, then the unlikelihood of a similar earthquake in Vermont is no comfort. The conditions that caused the meltdown, a conventional power failure and flooding, are entirely possible here," the state senator said.
"Well, a lot of people who have been making comments about Vermont Yankee and nuclear power following the Japan quake probably should not," Post said in response. "Their knowledge (about nuclear engineering), unbeknownst to them, is insufficient."
Post said Montpelier's current green energy policy is more of a prescription for disaster than Vermont Yankee.
"Doing energy efficiency first and then renewables is the most economical way to go; especially important when funds are scarce. Vermont providing huge subsidies for renewables before doing a great deal more in energy efficiency is costly and unwise," Post said.
"Agreed - an earthquake of Japanese magnitude is unlikely in New England, but that's not the question," McCormack said, in response to Post's comments. "Rather the question is whether or not a conventional power failure is likely. In New England? A power failure? Well, yes! Inevitable is more to the point than merely likely.
"Is a failure of in-house redundancies likely? At Vermont Yankee? Vermont Yankee malfunctions all the time. So, yes, Japan's nuclear problems have implications for us," the state senator noted.
The emotional debate over the risks and benefits of peaceful nuclear energy is likely to continue for years to come, even as safer, 21st-century reactor designs-such as Westinghouse's AP1000 and General Atomics' Pebble-Bed Reactor units-compete to replace aging 1970s-era nukes like Vermont Yankee.
Earthquakes: Richter facts
•The Richter scale was developed in 1935 by Charles Richter of the California Institute of Technology.
•The Richter scale is also known as the local magnitude or ML scale; it assigns a single number to quantify the seismic energy released by an earthquake.
•The Richter scale is a base-10 logarithmic scale calculating the logarithm of the combined horizontal amplitude (shaking) of the largest displacement from zero on a particular type of seismometer called the Wood-Anderson torsion.
•How to calculate an earthquake's magnitude: An earthquake that measures 5.0 on the Richter scale (similar to some reports of the April 20, 2002 earthquake in Vermont) has a shaking amplitude 10 times larger than one that measures 4.0.
Courtesy Wikipedia & U.S. Geological Survey