Nuclear and Chemical Wastes at the Hanford Reservation:
A conversation with Dirk Dunning
From the Environmental Review Newsletter Volume Three Number Five, May 1996
Introduction:
The Hanford nuclear weapons production facility occupies 560 square miles along the Columbia
River in south-central Washington state. It was established in an isolated area near the Columbia River
which provided the water necessary to cool the reactors. For forty-five years the facility ran several nuclear
reactors simultaneously, but instead of producing electricity they produced plutonium for our nuclear
weapons. Now closed, the site is the subject of a massive cleanup campaign by the Department of Energy
to find all the contaminated areas on the surface and beneath the site and to figure out how to retrieve or
contain the nuclear and chemical wastes and keep them from entering the Columbia River.
We spoke with Dirk Dunning - Hanford Program Coordinator for the State of Oregon Department
of Energy - about the history of the Hanford nuclear reservation and some of the dangers posed by the
massive nuclear and chemical contamination of the site.
Dirk Dunning has a B.S. in chemical engineering from Oregon State University, and many years of
engineering experience in fields as diverse as submarine nuclear power plants, industrial waste water
treatment, toxic and hazardous materials, and fire and building codes.
ER: Mr. Dunning, what is Oregon's stake in the cleanup of the Hanford nuclear reservation?
DD: Our first stake is being downwind and downwater from a high level waste repository site at Hanford;
we have a million people downriver. The second stake is a disaster preparedness issue; there are many
facilities and activities at the Hanford site which are quite dangerous. Several of those facilities have the
potential to have accidents large enough to have impacts in Oregon. So we work with the people on the
Hanford site in the state of Washington to insure that we are prepared should something go wrong. And we
do the best we can to insure that something does not go wrong.
We have a stake in transportation of radioactive and toxic materials moving to and from Hanford
through Oregon. If they use the road route it goes up over Cabbage Hill and then on through Ladd Canyon
and the conditions on those roads can change rapidly. Even if a truck sets out in fairly decent weather, at
the wrong time of year the weather can shift quickly and the road becomes icy and windy. This is just
outside the Pendelton area in eastern Oregon. Farther east the road runs into Ladd Canyon which has sharp
turns and severe cross winds. Both areas have severe road grades and there can be problems with runaway
trucks. If they use the railroad, the railroad runs through a canyon overlooking the Umatilla River, and if
there was an incident there, it could be very difficult to respond to it.
Another safety issue is more protracted: What happens to the Hanford site over time? A large
amount of the wastes that have been disposed of or buried or leaked at the Hanford site through its fifty
years has gone to the ground water already. There is an even larger amount of waste hanging in the soil
which may in the future move into the groundwater and then towards and into the Columbia River. This is
a problem today where some of the material along the river at the N reactor, at the K reactor, at the H and
D reactors and a couple of other locations is already moving into the Columbia River. At the N reactor,
strontium 90 is entering the river at levels well above the drinking water limits. At the D and H reactors,
hexavalent chrome is entering the river in an area of spawning beds for some of the native salmon at levels
toxic to salmon fry.
We also have an immensely large underground plume of tritium moving across the site and into the
river at the old Hanford town site, at levels well above the drinking water standard. In all those cases the
levels in the main Columbia River are not significantly elevated, and are below the drinking water
standards. But that does not take into account the effects as waste enters the river, particularly for the
salmon and many other organisms that live on the edges of the river.
ER: The contamination is below drinking water standards. Is that because of dilution after it enters the
river?
DD: Yes. But dilution is not immediate. As the pollutants enter the river they slowly mix into the river and
as they move downstream they mix ever more. But as they immediately enter the river, they enter in fairly
large concentrations and so in some sections of the river, the concentration of tritium is significantly above
the drinking water standard; a very short distance away, it is not. But the salmon redds are right on the
bottom of the river and so the mixing zone does not really help them a whole lot.
The plumes entering the Columbia River are not having a tremendous impact today - other than
the chrome which is of great concern. However, within about a hundred years, carbon tetrachloride from
the center of the site will be entering the river at high levels, possibly high enough to cause a major impact
on the river.
ER: That is not radioactive.
DD: No. It is just toxic; it is a known carcinogen. Even though Hanford is the best understood of any site
in the U.S. in terms of its groundwater, it is not understood well enough to get accurate predictions for over
a hundred years from now. But we do know the waste materials are moving through the soils and many of
them will reach the river because their half lives as radioactive materials are so long, or because they are
not degrading as toxic materials; carbon tetrachloride is a good example of that.
ER: When did the Government start making nuclear weapons materials at Hanford?
DD: Construction began in late 1942 and the first reactor was operational in 1943. The Hanford operations
were created to provide the plutonium and uranium for nuclear weapons production. The first reactor was
the B reactor, it was a prototype of a total of eight reactors that came later. The ninth reactor built at the
Hanford site for production of weapons material, plutonium, was the N reactor and it was the first one that
did not discharge its coolant water directly to the Columbia River. It came on line in 1979.
The original eight reactors were built by building a large pile of graphite blocks that were criss-crossed with fuel pipes, control rod pipes and safety control rod pipes. They brought in water from the
Columbia River, filtered it, added a trace of sodium dichromate to it for corrosion prevention, and fed that
directly into the operating reactor around the uranium rods. When the water came out of the back side of
the reactors, it was discharged into several multiple million gallon basins. The water had two to eight hours
of retention time in those basins where it had a chance to cool thermally, and to become a little bit less
radioactive. As the water came out of the reactor it was intensely radioactive. And by the time they
discharged it to the river, it was still radioactive enough that fish could not live in it.
ER: It would kill fish outright?
DD: Yes. From radiation exposure. The temperature of the water coming out of the reactors was at or near
boiling and when they were running the reactor as hard as they could, the waste water was upwards of 185
degrees F. They would take their reactor feed water from the near shore of the river and discharge out near
the middle, where the heat increase in the river did not affect downstream reactor operations so they could
keep as many reactors as they could running. The radioactive load to the river was quite large.
The discharged radioactivity was mostly from activation products where the river water itself was
made radioactive by going through the reactor. However, during the years of operation at Hanford, there
were 1963 fuel elements that failed in the reactors to one degree or another. Some of those were complete
failures, and when that occurred during the first years there was not a lot they could do about it. But they
developed means that if they detected a tremendous rise in radiation levels in the discharge water they
would turn off the discharge from the basin into the river and divert the waste water into trenches. So the
trenches became a large soil filter where the radioactive material was delayed in getting to the river. Many
of those trenches today are still a big problem because radioactive materials in them are slowly seeping into
the river. The area called N springs at the N reactor is an example of that, where strontium 90 levels are
extremely high entering the river.
The reactors along the Columbia River converted some of the uranium 238 in the fuel to plutonium
239. They discharged the fuel periodically from the reactors into holding basins behind the reactors where
they would allow it to cool for 90 to 120 days. During that time the short-lived fission products decayed
away and the decay heat dropped greatly. More importantly, by the time you have reached 90 to 100 days,
iodine 131, which has about a nine day half-life has gone through ten half-lives of decay and is pretty
much all gone. So after that decay occurred they would take the fuel from the basins and transport it to
facilities in the center of the site where they would chemically dissolve the fuel. This released some of the
fission products to the atmosphere, particularly some radioactive noble gases and radioactive iodine and
ruthenium. They separated the uranium and plutonium from the radioactive fission products and fuel
cladding. They recycled the uranium and converted it back to metal to produce new fuel. The plutonium
was sent on as a plutonium nitrate solution to the plutonium finishing plant. At the plutonium finishing
plant they converted the plutonium nitrate solution first to plutonium fluoride and then to plutonium metal.
And the so-called button they produced was shipped to Rocky Flats for the final finish weapons production.
During the early years they didn't separate the uranium and it ended up going to the tanks as waste. Later
on they found they needed that uranium and they recovered it.
ER: How long were the first eight reactors discharging their coolant water into the Columbia River?
DD: They were discharging through all of the sixties for the most part. The last of the first eight reactors
ceased operation in 1971, that was K east reactor, the last of the single pass reactors. The original B reactor
ended its operations in 1968.
ER: Were these new generations of reactors new and improved models?
DD: Actually not. The B reactor was a completely unproven design. The very first reactor built was the
pile in Chicago, and I have heard people say that it was the A reactor. I have also heard that the A reactor
was intended to be built upstream of B reactor, near the Vernita bridge. But, the B reactor was the first at
Hanford. As it was designed by DuPont and Enrico Fermi and the other physicists, it was intended almost
as a proof of concept and just to be able to produce enough plutonium to produce a weapon. When they
designed the reactor, the DuPont engineers had the data from the physicists about what would be required,
and being the good engineers they were, the first thing they did was add about ten percent to the design.
They figured that if the physicists said it was big enough to have so many fuel rods, they had better allow
for more than that. As it turns out there were some physics things that did happen during the operation of
the reactor that were different than anticipated and so not too long after they started up the reactor for the
first time, it shut down on its own. One of the fission products acted as a nuclear poison; it was taking up
some of the neutrons that run the reaction and so the reactor was not large enough to run but because the
engineers had allowed for this, they were able to put fuel into the remaining fuel channels and the reactor
did run. The reactors that came after B; the C, D, F H and K reactors, were each bigger reactors but the
design was almost identical to the original B reactor. There were some modifications but for the most part
they were just made bigger and more powerful. The whole philosophy during the production years was
focused on how to produce the maximum quantity of plutonium. You can see by looking at where the fuel
elements were that failed in the reactor cores that from an engineering perspective they were pushing the
cores as hard as they could and there was allowance for a certain amount of failure. So it was an
engineering driven operation, not a safety driven operation.
ER: The operators pushed the reactors to the failing point and lost containment of the nuclear fuel?
DD: Yes. In a reactor the most powerful region is the center of the core and it gets less powerful as you go
out from there. The fuel rods would go in horizontally and the water flows from the front face through the
reactor to the back face. Its inlet temperature was whatever the river temperature was and its outlet
temperature was boiling at the back face of the reactor. The fuel failures occurred in an area just behind the
center of the reactor. That indicates the temperature there was hot enough that some of the water boiled to steam and there was two phase flow. In the two phase flow the heat transport from the fuel to the water is
not as good as it is with liquid water, and there is greater probability that the fuel will overheat and fail;
which is what you can see in the records of the reactors. It is not direct evidence where somebody said
what they did, but it becomes very apparent when you look at how the reactors operated and failed.
ER: How could they get away with dumping radiation into the Columbia River?
DD: The whole operation was run very much in secret. The people at one plant did not talk to people at
another plant except minimally. When the facilities in the middle of the site - PUREX, REDOX, and
other processing facilities - produced waste, they would talk to the people in the tank farms who had
responsibility for taking that waste only enough to tell them how much they were producing. There were
not a lot of discussions of what the impacts were, at least not at the lower levels.
Throughout the history of the site the tanks were something that was going to be taken care of
later. There was always a rush for plutonium production and the waste was something we would handle
another time. The waste tanks were only designed to last twenty to thirty years, and during the initial
design phases, the engineers were very forthright that they expected they would produce plutonium through
the war years and that following the war, the reactors would be shut down and then they could figure out
what to do with the waste. But after the war ended the Cold War started in earnest and there was no
opportunity to slow down in production or to do anything about the waste. And being a closed operation
and behind classification, there was never input enough from the outside for people to recognize how large
this problem was. Cost was always an issue, very much in the forefront of everyone's mind. So they would
do things as inexpensively as they could and in many cases that resulted in the problems we have today.
ER: How would you prioritize the problems at the site?
DD: The risks at Hanford come in several different kinds and over different time frames. There are those
things which are absolutely urgent risks today, and those things that will be in all probability very large
risks in the future if we do things wrong. One of the issues that has come to the forefront in the minds of
the people at the Department of Energy is that there are a number of risks at the site that are quite urgent.
The most notable of these has to do with the tanks on the site. As they processed the fuel they used a
variety of different organic chemicals, in addition to the nitric and other powerful acids. [Organics are
chemicals with a carbon backbone. ed.] Over the years they very seldom had as much tank space as they
would have liked, so they wound up concentrating waste in the tanks when they ran out of space. In some
cases that meant the tanks overheated and vented material to the air. In that case they would go through
long campaigns of removing the most intensely radioactive materials, cesium 137, strontium 90. They had
other needs for medical and other reasons to recover other isotopes, so they mined the waste periodically.
As they ran the tanks, many of the fission products were precipitated out as solids in the tanks.
They operated some tanks in a cascade with waste going first into one tank, then overflowing into a
second, then overflowing into a third. The overflow from the third tank was sent to cribs, trenches, reverse
wells or other drain equipment, into the soil. In the cases of those operations as well as many cases where
they were discharging directly into the soil they attempted to determine how much ion exchange capacity
the soil had. They then utilized each disposal location just to the point that it did not release to the ground
water. So there are very large quantities of radioactive material in the soil.
With all of this movement of material around through the tanks, it created a situation
where every tank in the tank farm is unique; they all have their own chemical makeup; they are all
different from one another. It also creates a problem where many of the wastes are not compatible with
each other. In a number of the tanks the chelants used to hold on to some materials are reacting with
aluminum oxide and caustic to slowly degrade and convert into hydrogen and nitrous oxide gas. The gas is
being trapped down low in the tank under a layer of solids that have formed a mat. Slowly over time as the
gas builds up, the sludge on the bottom of the tank becomes so buoyant that it lifts the waste above it; the
tank waste in effect turns over and releases a large burp of gas. You end up then with ten to fifteen
thousand cubic feet of hydrogen gas along with about an equal volume of nitrous oxide gas. These two
gases are even better at burning together than hydrogen and air, and with a very minor spark you could
have explosions in the tanks. There has been a lot of discussion about how big that explosion might be and
whether or not it would be enough to rupture the tops on the tanks. The people on the Hanford site believe
that it would not. However in any event it would cause enough of a release that it would probably dislodge
the ventilating equipment on the tanks and cause a release to the air, even if it did not fail the tank. In
addition, the pressures generated in an explosion would probably be large enough to cause the failure of the
tank itself so that the tank waste then would be allowed to seep into the soil. That is one of the problems in
the most urgent category.
The other kinds of risk on the site are somewhat different. They have to do with a large quantity of
radioactive spent fuel that is stored in a couple basins on the site. Towards the end of the operations at
Hanford, there was pressure from many quarters to shut down the chemical reprocessing. There were also
economic pressures to continue running the N Reactor which was producing power as well as producing
plutonium. So we ended up in a strange situation where the money was removed from the PUREX facility
and it was forced to shut down while the N Reactor continued to produce spent fuel. DOE intended to
continue operating PUREX; it was just a question of when they were going to restart. They did not clean
out the plant. They just turned it off. And so, for the past many years, PUREX sat intact with all of its
solutions in place, ready to run, and yet it was not able to.
ER: What does PUREX stand for?
DD: Plutonium URanium EXtraction facility, and REDOX is the REDuction OXidation facility.
The problem this created then, was that as the N reactor ran, it was producing spent fuel which had
no place to go. And so they accumulated it in two of the basins on the site which were not being used,
those are near the K reactors. The fuel that came out of all the reactors at the Hanford site was metallic
uranium, and by its design it was never intended to be kept around. It was intended to be processed shortly
after it was produced.
They would push the fuel out of the fuel channels and allow it to drop vertically from the back of
the reactor into a pool and the fuel then was put into storage. If it was processed in the first six months to a
year or so, it did not cause a lot of problems, other than some releases of radioactive materials into the
basin water; and they had purification facilities to control that. But in the case of the fuels from the N
Reactor in the K basin, most of it has been there for over ten years and so this fuel has been slowly
corroding in the water. Today these two basins have slightly different problems: in the K East basin where
the fuel was stored exposed directly to the water in open containers, the fuel has corroded badly enough
that along with the sand that has blown into the building and the corrosion of all of the iron structures in
the pool, there is now about seven inches of radioactive uranium, iron oxide and sand sludge on the bottom
of the basin.
In the K West basin they lined the basin with epoxy and they put the fuel into closed containers.
Unfortunately in closed containers as the uranium reacts with water it produces not only uranium oxide but
uranium hydride which is quite flammable. In the case of the fuel in both basins there is a concern that it
may be pyrophoric; that is, it may burn when exposed to air. British Nuclear Fuels reported about some
similar fuel they had, of about similar age, that reacted with the air when they removed it from pool
storage. In some cases within twenty to thirty minutes it was glowing at red heat and ignited.
ER: The fuels react so strongly with air they burn?
DD: That's right. Decay heat from radiation and also chemical reactions from exposing it to the air was
enough in some cases.
In addition, the basins were never designed for the kind of earthquakes we now know can occur
there. The original design of the B reactor was carried forward into the later reactors. The reactor building
was built first along with the base of the reactor; then the basins were built abutting the reactor building.
That left a large construction seam between the two, where a part of the basin is actually a part of the
reactor building. The reactor buildings and the basins were not directly joined. There is a masonite seal
between them but the two structures are just sitting up against one another. In a large earthquake, because
these structures have such different masses and shapes, there is a good chance they could walk away from
each other. If they did that, obviously it opens a hole where the basins can drain. To respond to that DOE
has put in place some metal gates in a portion of the pool to prevent that from happening. But even then,
the basin itself was not designed for large earthquakes. So it is important that the fuel be removed.
The tanks and K Basins fuel are probably the two largest risks on the site today. The next largest
has to do with earthquakes in general. There is a lot of plutonium in the plutonium finishing plant and a
lot of radioactive materials in many of the buildings which were not designed for large earthquakes. As a
consequence, if we are unfortunate enough to have a quake of sufficient size, any one of those facilities or
a couple of them might have releases which can have some impacts on site. For those kinds of impacts, we
don't expect it to go off site or if it does, not to go very far. However, we continually prepare for the worst.
For the workers on site this is a bigger issue because they would be directly affected by an earthquake.
Those are the near-term risks. There are also other risks associated with handling of material and transport
and those types of things. But for disaster hazards, those are the largest.
For many of the wastes the far future is the bigger concern. Where if you look at the long-lived
radioactive materials, the ones with half-lives in excess of one hundred years - many with half-lives in
excess of a million years, several of them are of great concern. One is iodine 129 because it is mobile and
moves with the water. Another is technicium 99 which has a similar problem. Some of the radioactive
wastes are cationic and tend to bind to the soils. Even then, they will move slowly through the soils. These
include isotopes of plutonium, americium, uranium and some of the other actinides. The risks come from
many places on the Hanford site, including the tank waste which has leaked. In excess of half a million
gallons of high level wastes leaked to the soil in one tank failure at tank A 105.
ER: That's in addition to the trenches and intentional discharges?
DD: Right. Then you have the trenches, the reverse drains, the cribs and a number of other facilities, each
one is built somewhat differently but they have the same general purpose. But those were all direct
intentional discharges of less concentrated radioactive waste. Then in addition, there were a lot of burial
grounds. Particularly in the early years, if they ended up with material that was highly contaminated, the
response was to bury it. Some of that waste is buried in locations that are unknown.
ER: But on the reservation?
DD: On the reservation. In other cases in the early years there were not the same kinds of limits as there
are today on how you handle plutonium contaminated wastes. And so the transuranic or plutonium wastes
were buried in burial grounds under conditions that are not acceptable today. That waste may or may not
ever be removed from the site. And if it is not, it will slowly move away from where it is now. Because
plutonium has a 24,000 year half life, that poses a risk for a very long time.
ER: The argument is how slowly will it move away from the site?
DD: That is precisely the argument. The argument by many of the engineers on the site is that this material
is immobile and will not move. However, in many cases in the past we have seen that belief turn out to be
wrong. In particular, at the plutonium finishing plant there were a couple of disposal facilities where they
expected the plutonium would not move and it has moved considerable distances from where they thought
it would be. At one facility they processed plutonium and discharged contaminated solvent into the soil
column at a place called the Z9 crib. They discharged on the order of a thousand tons of carbon
tetrachloride. Carbon tetrachloride is a dense non-aqueous liquid, a known cancer causing agent, and it is
believed that a large quantity of it is underneath the groundwater below the plutonium finishing plant. That
creates a problem because it will continue to leach into the ground water as the ground water moves by.
Another large quantity of carbon tetrachloride is hanging in the air space of the soil. So there are
processes in place today where they pull air out of the ground and run it through activated carbon, and
pump groundwater and treat it to remove carbon tetrachloride. Mostly this is intended to remove the vapors
from the vapor space and to hold the contaminated material where it is, under the groundwater. The
carbon tetrachloride carried a small amount of plutonium with it so that plutonium was discharged along
with the carbon tetrachloride into the Z9 crib. During the 1970s they recognized they had a problem in the
Z9 crib and they went back and mined the crib and they removed over ninety kilograms of plutonium from
the soil. [Ninety Kg is about 200 pounds. ed.] At the same time they also drilled a couple wells through
the crib to find out where and how deep the plutonium was. They found there were some leakage paths
down through the soil they had not anticipated and plutonium was found quite deep under the crib. So there
are a lot of problems there.
In effect all of the disposal units associated with the plutonium finishing plant have plutonium in
them and this is one of the problems on the site that almost everybody expects DOE won't be able to solve.
Those areas will have to be off limits effectively forever.
ER: How does one prioritize a problem that gets more serious thousands of years from now?
DD: It becomes difficult. There is a longer time you can work on it. It is not as urgent as tanks that may
explode or fuel that may burn. There is a document - in internal review at US DOE - called the
Hanford Remedial Action Environmental Impact Statement. In that document are maps showing what DOE
and its contractors expect will be the fates of many of these materials over the next 10,000 years. This
particular EIS is limited: it does not include the tank wastes and many of the associated disposal facilities,
it does not include the reactors themselves and some of their disposal facilities, but it does include the other
waste sites surrounding all of those. It shows large areas of the Hanford site, particularly to the north of the
center of the site running up towards the Columbia River, where there is a large section of land that the
cancer risk over the next 10,000 years becomes quite large. Over a large triangle of land it exceeds one
percent; and that ends up going all the way to the Columbia River. They used several different scenarios:
One where people live there; one where people work there; one where they are growing crops; and one
where it is just for recreational use six days a year. And in each of those scenarios - with the exception of
recreation - the cancer risks are about the same. Recreational is quite a bit less but the risk is still large.
The second thing to know about the one percent increase in cancer risk is when the EPA or even
the U.S. DOE estimate the cancer risks, one percent is an upper limit where if you exceed that you are no
longer in a range where you can use a linear model. So it is hard to project what the risk is above one
percent. So in some cases they will say greater than one percent and that means anywhere from one percent
up to certainty.
ER: One percent means given an exposure to that radiation over time the number of people who would be
expected to get cancer would be an additional one per hundred?
DD: Yes. That's correct. So the risks potentially from that are quite large. The advantage we have is that
over the next hundred or so years we have to prevent much of that from happening. But we can also make
decisions that do not prevent it. There are costs today and there are also costs in the future. It is relatively
easy to measure the cost today; it is hard to measure the cost in the future.
ER: This recapitulates the problems they were faced forty years ago where they were making decisions that
created problems for us now.
DD: It does. And some of the people on the Hanford site do not believe in some of the aspects of the
cleanup. In particular there are a number of people on the site who have argued that the tank wastes should
be stabilized in place by adding sand and concrete and then putting a large barrier over the top and then just making the whole place a restricted area indefinitely and allow radioactive decay to take care of it.
Copyright 1996 Environmental Review