My friends who are naval aviators have a saying that seems appropriate here – “tis easier to seek forgiveness than to ask permission.” For the past couple of days, I have been trying to ask permission to publish the below speech text, but have been unable to make contact with the originator. I will keep trying to find Mr. Miles, but in the meantime, I think that the talk that he gave at the Keese School of Continuing Education on March 24, 2011 is so important that it needs to be shared widely.
Based on the correspondence that I have had so far on the topic, I do not think that Mr. Miles has any expectation that he will earn a lot of future revenue from retaining all rights to this work. If you are reading this, Mr. Miles, please accept both my thanks for producing the talk and my apologies for publishing it without your permission.
Update: (April 4, 2011) With a little help from my friends, I made contact with Murray Miles yesterday and obtained his belated permission to publish. Here is what he told me:
“I am delighted that you want to send my message onward. Yes, of course you have my permission, although I had not been aware it was needed. The report seems to have gone viral according to one of the handful of people I sent it to initially.
It is great to find nuclear navy people spreading the word.”
Mr. Miles also corrected a line in the Decay Heat section to more accurately reflect the amount of thermal energy produced one day after shutdown at unit 1. End Update.
The following is a direct quote of the talk, including the postscript at the end.
FUKUSHIMA NUCLEAR ACCIDENT
THE KEESE SCHOOL OF CONTINUING EDUCATION
MURRAY E. MILES
MARCH 24, 2011
I PLANT PRIMER
The three other talks I have given to Keese School each took about a year to prepare. You all get to judge the effect of my having only 48 hours to prepare for this talk.
You have to be very careful in an emergency phase about what to believe. I have used many written sources and some by phone to get to the stage today where I can finally put together a reasonably credible analysis. This is day 13. Some of what I think I know today will prove to be wrong.
I am painfully aware of a key approach that I have trained on for 50 years. When a problem comes in, you had better assume that it is much worse than the people doing the reporting think it is. It often is much worse. You need to get your arms around the whole problem and work your way into the smaller issues. It destroys your credibility if you keep finding the issues are bigger than you expected.
I happen to know something about these Japanese plants. Oyster Creek on Barnegat Bay in New Jersey went on line one year before the number one Fukushima Daiichi plant and has the same design. I worked there for 20 years, and was a member of their President’s nuclear safety board.
These six Daiichi plants were designed for an earthquake of 8.2 on the Richter scale but the quake was a 9.0
ALL SIX PLANTS COMPLETELY SURVIVED THIS 9.0 QUAKE.
In going the extra mile to protect from earthquakes, Tokyo Electric put the electrical switchgear in the basement. So they had electrical power after the quake. However the tsunami flooded the basements, and there was no way to pump out the basement. The water obviously shorted out the circuits.
To compound the problem, they routed the wiring for the instruments in the control room through this basement switchgear. Therefore after the flooding, all six plants were without power, without emergency diesel generators, without instrument readings to tell the status of the plants, without lights. I have not seen these two disastrous design failures discussed on television.
The newest units 5 and six are offset a little from the other four. In these two there are parallel electrical circuits that did not go through the basement switchgear. These two plants are OK. The reported fire in unit five was wrong. A helicopter some distance away saw the fire from unit 4 and thought it was from unit 5. Except for the psychological problem, units 5 and 6 probably could go back into operation in the not too distant future.
Unlike any other types of power plants a nuclear plant needs power to keep the reactor fuel cool after shutdown. The operating plants DID shutdown immediately at the quake and nuclear fission ceased. But radioactive elements in the reactor fuel continue to decay and that produces heat. One day after shutting down, the heat generation is still one percent of what it was at power. In round numbers, that one percent was 10,000 kilowatts of heat. This heat turns the water into steam above the reactor fuel core.
If you do not continue pumping water into the reactor pressure vessel, the water will eventually drop below the top of the fuel. Steam does not conduct heat away from the fuel rods anywhere near as well as water and the fuel rods heat up. Above about 3000 degrees Fahrenheit the zirconium metal tubing holding the uranium pellets begins to melt. Before you get to 5000 degrees the uranium melts.
There has been a lot of bad information in the media on meltdown. Some scare stories feature the Jane Fonda movie on China Syndrome that was in theaters just before the Three Mile Island accident. They have the fuel melting down through the bottom of the reactor vessel and wreaking havoc on the environment, maybe even to the center of the Earth.
But we have actual knowledge of what really happens when uranium fuel melts. At Three Mile Island it took years to find out that half of the fuel melted. Some of it puddled in the bottom of the reactor vessel. But it penetrated only five eights of an inch through the five inches of steel in the bottom.
I also happen to know a lot about Three Mile Island. I retired from federal service the year of the accident and immediately went to work at Three Mile Island. I worked there for twenty years and was a member of their president’s nuclear safety board. I even dressed up and entered the containment structure of the accident plant.
Has the fuel melted in Fukushima? Probably yes. At this point the answer is unknown and I think It won’t matter for a long time how much of the fuel melted. We are certain the fuel rods failed and released radioactive fission products in vast amounts into the reactor vessels.
Our question is how are those vast amounts of fission products contained. In Units 5 and 6 there appears to be no problem because the fuel has not failed. Water was kept in the reactor core to keep the fuel cool. In unit 4 all fuel was removed from the reactor vessel well before the earthquake to allow repair work inside the reactor vessel.
Something nearly miraculous occurred to prevent units 1, 2, and 3 from early catastrophic failure. About eight hours after the earthquake Tokyo Electric Company made the decision to pump seawater into the reactors and reactor containment buildings of units 1, 2, 3, and 4. This was a thirty billion dollar decision to destroy these plants beyond all possibility of recovery. This could not have been ordered by their regulators or their government. It would not have been possible for these bodies to make such a decision in this time frame even if asked. Cold salt water on hot stainless steel causes irreparable damage.
The plants are designed to allow, in extremis, seawater to be pumped either directly into the reactor vessel or into the steel containment outside the reactor vessel or into both. The valves are designed to fail in the open position when there is no electricity. Thus seawater was pumped into both to provide cooling to the fuel. They chose to include unit 4 which did not need cooling presumably because the piping systems are inter-connected and they figured there was no way to keep the saltwater completely out of unit 4.
It’s too bad they were unable to keep injecting seawater.
So where does this leave the Fukushima Daiichi plants 1,2, and 3?
Units one and three appear to be getting under control. Their steel containments around the reactor vessel are intact. The widely- viewed pictures showing destruction of the upper part of the reactor building are scary, but this damage does not affect release of radioactivity from the fuel in the reactor.
The status of unit 2 is uncertain. It had a hydrogen explosion inside the steel containment where it could do more important damage than the hydrogen explosions in the secondary containments of units 1 and 3.
Television coverage has emphasized the so-called lethal danger of the plutonium in the fuel of one of these units. This is nonsense. Yes, the reactor fuel started life with some plutonium in it. This uses up plutonium that might otherwise be available to make nuclear weapons. However all uranium reactors generate plutonium and a substantial fraction of the power they produce comes from fission of plutonium.
Eight other nuclear plants nearby at Fukushima Daini, Onagawa and Tokai are safely shutdown. It will be interesting to see how long it takes the Japanese to get over the overwhelming psychological problem of getting these sorely needed power plants back on the line.
At Three Mile Island it took five years to get the other plant that was not damaged back to power.
II. FUEL POOL
Since early in this emergency, I have thought that the overwhelmingly biggest problem would be the fuel pool in Unit 4. Allow me to develop some background for you.
New fuel comes in long rods less than an inch in diameter and perhaps twelve feet long. I have handled these but I had to wear cotton gloves to protect the metal from contamination from my hands. USED fuel rods have a radiation level of around one million rem per hour. For reference, one thousand rem to your whole body will kill you.
During refueling, bundles containing of the order of 100 rods are moved from the reactor to a fuel pool. Think of it as a swimming pool 45 or 50 feet deep so that the vertical fuel bundles are covered by at least 30 feet of water. The water both cools the fuel and provides radiation shielding.
These boiling water reactors have their fuel pools in the attic over the reactor steel containment. The top cover of the steel containment is about the level of the top of the pool to make moving fuel easier. Think of the floor level of the pool as the fifth floor of the reactor building. This attic is referred to as a secondary containment, but it is just to protect from the weather. As you see from the television pictures, it blows away easily. Having the fuel pool water exposed to the open air is not the big problem. The water is radioactively contaminated but not to high levels. You wouldn’t drink it and it would be better if you did not swim in it.
LOSS OF WATER
Fuel pool water has to be circulated through coolers to keep the water from heating up and boiling away. Without power, the water level will decrease. Fuel damage follows when the water is below the top of the fuel. The zirconium metal surrounding the uranium reacts with steam to form hydrogen which can explode. In this situation when the fuel melts, the fission products are released. There is no effective containment. The radiation levels are so high that it is hard to get near enough to do anything, particularly from the air. At least on the ground you can get some radiation shielding from buildings.
The potential loss of fuel pool water is by far the worst radiological problem I have been concerned about in my 30 years working on commercial nuclear power plants. We now have it in Japan.
UNIT 4 FUEL POOL
Fukushima Daiichi has one fuel pool for each reactor and a seventh common pool that has not been in trouble. They also have some older fuel stored in dry casks perhaps a quarter of a mile away from the plants. The unit 4 fuel pool is nearly full with around 200 tons of fuel in a water tank with a capacity of around 400,000 gallons.
You need to hear one more complication in the design. The fuel pool is really two pools separated by a gate. Fuel removed from the reactor goes first into the small, upper pool which is only 20 or 25 feet deep. Later they move the fuel to the big, deep pool. There was apparently only a little fuel in this upper pool at the time of the quake.
This UPPER pool broke. The three-eighths inch steel liner is cracked and will not hold water. The concrete wall in front of this upper pool fell off. Fuel was severely damaged probably by explosion. Temperature profiles measured by helicopters show clumps of hot stuff that must be fuel scattered around the floor area. This scenario is consistent with the numerous reports of fire in unit 4.
This is a real nightmare. But the main fuel pool in unit 4 appears intact and full of water. The spread of radioactivity came fortunately from a small amount of fuel.
Getting water into the fuel pools has attracted great attention. You saw the helicopters dropping water. In efforts to spray water you have seen the Riot Police helping, 6 fire engines from the Self Defense Force, 14 vehicles from the Tokyo Hyper Rescue Unit, and even a United States military high-pressure fire engine have been involved. The most successful effort to get water to a fuel pool was finally a 160-foot arm normally used for pouring concrete. I saw one of these recently at Asbury pouring concrete for the Courtyard Homes.
The Japanese are consistent with international standards on radiation exposure limits using 2 rem per year for radiation workers. In early action they raised the limit on site to 10 rem for the emergency. Later they raised the emergency limit to 25 rem. Any worker getting near this limit would be forever removed from radiation work. This number has been widely used for decades in emergency plans I am familiar with. In round numbers, 25 rem increases your risk of dying from cancer by one percent. Your risk of dying from cancer before irradiation was 20 percent, and this would raise it to 21 percent. The worker is unlikely to notice any effects of this radiation, although special blood tests could show some changes. We probably have experts in this audience who could count dysenteric breaks of chromosomes.
The Japanese have controlled the radiation of their workers within their limits. They are using both Tokyo Electric employees and contractors. Five workers have received slightly above 10 rem and one just over 15 rem at 13 days into the emergency. There have been no deaths from radiation and none seem likely.
To help emphasize this is NOT like Chernobyl, 600,000 workers, called liquidators, cycled through Chernobyl. Some worked only seconds. Their average radiation exposure was 10 rem. 59 workers died from radiation, including helicopter pilots. The deaths took months. Very high doses are required to cause quick death from radiation.
Because of the extremely difficult working conditions, the rate of industrial accidents is above normal. Twenty-three workers have been reported with injuries, none major, and 7 of them were taken to a hospital. Two Tokyo Electric employees are missing. Their last known location was in the Daiichi Plant 4 turbine building. At the Fukushima Daini plant one worker died falling from a crane.
The working conditions are difficult. Controlling the radiation exposure of workers requires exceptional effort because of the existence of very high radiation levels, and because surprises are continuing.
There are lots more issues related to this nuclear accident that are worth talking about. Here are a few of the ones I had in my outline 48 hours ago that got displaced by the time it has taken to discuss plant and fuel pool problems:
1. What is the future of nuclear power in the U. S. in the aftermath of the accident?
2. The yellow “radiation” suits the workers wear do not protect the workers from radiation.
3. Fires are a major nightmare at this stage because of the kinds of radioactivity they might spread.
4. What is the future of Daichi Units 1, 2, and 3? Entombment is always discussed, as at Chernobyl, but at Three Mile Island the fuel was finally removed.
5. Many members of the public offsite have been radioactively decontaminated. So have workers.
7. Why is the television coverage so poor? Why don’t they get reasonable experts to talk?
8. How well have Tokyo Electric and the Japanese Government handled their communications with the public?
But before I turn this session over to you for questions, there is one more subject I have to talk about.
V FIFTY MILES
I look for political wisdom and its opposite in assessing emergencies. I have one issue that screams for attention. The Japanese took early action to evacuate people both from the Fukushima site and outside it. Quickly they used 2 kilometers, then 3 kilometers, then10 kilometers, and finally on the second day they ordered a comprehensive evacuation out to 20 kilometers, which is 12.5 miles. They also have ordered those in the ring from 20 to 30 kilometers to stay indoors and they are providing help for these people.
The U. S. uses a 10 mile Emergency Zone for reactors. The difference from the Japanese 12.5 miles just comes from using round numbers in kilometers (20) or miles (10).
However, the United States ordered its people evacuated for 50 miles from the reactors. I consider this an egregious error. Do we think the Japanese are not being safe enough? Do we care more for our people than the Japanese do for theirs? Do we have information we think the Japanese do not have?
We use the same international radiation standards they use. The distance of fifty miles seems to be used in emergency planning only for expanding the area to measure environmental radioactivity.
This 50-mile decision must have outraged the Leaders of Japan. I presume it upset the Japanese people too. It is being used in the U. S. To demand shutting down nuclear power at Indian Point because it is 37 miles from 18 million people in New York City.
The Chairman of the Nuclear Regulatory Commission seems to have made this decision on 50 miles himself against the advice of the NRC Staff. I evaluate this very bad decision as part of the campaign by the leader of the United States Nuclear Regulatory Commission to stop nuclear power in the United States.