Wednesday, September 30, 2009

Episode 72 - Sea Stories from the USS John C. Stennis


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I’m writing this from the nuclear powered aircraft carrier USS John C Stennis. We're somewhere off the coast of California steaming north to the ship's home port in Bremerton, Washington. It's a pretty nasty day outside; the Pacific Ocean is cold and dark blue with cop, white caps and salt spray reaching up from below to sting your face. The wind on the flight deck is a chilly 58 knots and seas are six to eight feet. Inside the ship there is a gentle rocking motion and it's a bit on the cool side. Most everyone is wearing sweaters or light jackets although it's the middle of summer.

I had an opportunity to chat with the ship's captain yesterday, and I was reminded of the unique and impressive club to which he belongs. To be the commanding officer of a nuclear powered aircraft carrier an officer must first have been a distinguished naval aviator, a pilot with thousands of hours of flight time and hundreds of carrier landings. Then, at the rank of Captain, they are sent to Nuclear Power School and qualify as Engineering Officers of the Watch along with all the other navy nukes just out of college. As a result, carrier CO's are both aviators and nukes – a combination that puts them in a very exclusive fraternity.

I also had lunch the ship's medical officer, a former navy nuke who after his first tour of duty decided to attend medical school where he did residencies in flight medicine and family practice. As a result, he's a nuke, a flight surgeon, and a family practice physician; the perfect combination for the head physician aboard a nuclear powered aircraft carrier! Today we toured his medical and dental facilities where he manages a staff of physicians, medical corpsmen, dentists, nurses and other staff; a virtual floating hospital capable of meeting the routine and emergency care needs of more than 6,000 people aboard the Stennis and several hundred more in other ships assigned to the carrier group.

This is a floating city of 6000 that never sleeps. At all hours of the day and night the ship is alive with activity. From the bridge where they guide the ship through the water to the bakery where they create delicious pastries and bake hundreds of loaves of bread each night, sailors work around the clock to keep the ship safe, clean, on mission, and very well fed. And except for aircraft, forklifts and other mobile equipment all of the energy used on board comes from the two nuclear reactors operating a few feet below where I sit.

Evolution of Ship Propulsion

On my flight to San Diego where I joined the Stennis I finished reading the second chapter in the story of the Adams Atomic Engine by my friend Rod Adams. Rod will be happy to hear that he's stimulated a great deal of contemplation on my part, hence this podcast.

If you've listened to this show before you'll know that I'm an engineer, a manager, and a nuclear reactor operator. I've spent most of the last 25 years working on or around the kinds of nuclear energy facilities that have dominated land-based commercial and sea-based naval nuclear power for the last fifty years. I'm referring to what we call light water reactors because they use water as a coolant and to slow down or moderate the neutrons to make them more readily absorbed by the fuel. In these energy facilities the fuel atoms fission or split apart which releases fast moving particles. These particles bounce off nearby atoms and molecules creating friction.

As the fuel and surrounding material heats up from this friction, the heat is picked up by the ordinary water coolant as it passes through the reactor. This hot water is used to create steam either in the space above the fuel or in big tanks called "steam generators." The steam is blown through turbine blades to make the turbine spin, and the turbine is attached to an electrical generator that makes electricity by spinning coils though a magnetic field.

This design was a natural evolution for power plant designers sixty years ago. Nuclear energy was new on the scene, but they already had decades of experience with steam turbine power plants fueled by coal, oil, and gas boilers. When they set out to harness nuclear fission to make electricity, they were able to take existing steam plant designs and replace the boilers with reactors. This reduced the number of uncertainties because the only new technology was the nuclear reactor. Rod Adams points out in his story that the light water reactor was a logical evolution of existing power plant designs during a period where time was of essence and expertise in the new technology was limited.

As I thought about the origin of light water reactor designs, I realized that I experienced a very similar evolution in my personal education and experience; first I learned how to operate oil-fired steam ships and then moved on to learn what it meant to replace the boilers with nuclear reactors. It was an exciting time for me because I got to experience first hand the benefits of nuclear energy.

My Sea Story

I'll never forget my very first trip across the Atlantic as an Engine Cadet on the container ship SS Edward Rutledge when I learned that we were burning two barrels of oil per mile. One morning two or three weeks into the voyage the Chief Engineer, Thomas Taylor from Terre Haute, Indiana looked over his steaming cup of black coffee and said in an unexcited voice, "Well John, we just burned a million dollars in fuel." I almost fell out of my chair! In 1981 a million dollars was an almost unimaginable amount of money to a 21 year old middle-class kid (also from Indiana, BTW)! The type of oil burned by steam ships is called “bunker C" and it's one of the lowest grades of refined petroleum. It's thick and sticky and has to be heated up with steam before it can be sprayed into the boilers where it is burned. Sometimes other fuels are used: on the SS Arco June, a super tanker I worked on that brought Alaskan oil to the US west coast, we had to switch from bunker C to low sulfur oil when ever we traveled in and out of Long Beach harbor because of the tight air pollution rules. We had to store that fuel oil in special heated tanks because it was like tar and would not pump at room temperature.

Fuel oil and hot steam pipes in a power plant are a dangerous combination; fuel oil that comes into contact with hot steam pipes can easily ignite and there were stories galore of major fires and gruesome, painful injuries and deaths. I also learned how hard we had to work to prevent even a drop of fuel oil from leaking or being spilled into the sea because of the impact to the environment and huge Coast Guard fines. Fuel spills were relatively easy to trace back to the guilty ship because the Bunker C would cling to the hull of the ship and leave a trail of sheen on the water for miles.

Later as I studied nuclear engineering and learned to operate nuclear power plants it seemed almost miraculous how much energy could come from so small a package, and how clean and safe nuclear power was compared to oil. With nuclear energy there was no need for routine refueling, no hazard of oil fires, no concern for oil spills, and no air pollution. The switch from oil to nuclear was a logical and natural evolution to a cleaner, safer, and more compact energy source.

The Story of Chief Engineer Thomas Taylor

Chief Taylor, who was in his 60's at the time, had been through a similar transition during his career. He had started as a skinny 16 year old kid shoveling coal into the furnace of a Great Lakes steamer. During World War II his father had traveled with young Tom the two hundred miles or so from Terre Haute north to Gary, Indiana on Lake Michigan to sign his son on as a coal tender, a job that exempted him from the war draft. The Chief chuckled when he told this part of the story: when his new boss, the boiler room fireman saw Tom, his new man, the fireman cursed, "God Dammit! They're sending me babies!" and threw his hat on the floor in frustration and stomped on it. Chief Taylor had obviously proved himself and eventually worked his way up through the ranks as ships switched from coal to oil. He felt the same wonder as I later felt about the switch to nuclear because compared to coal, oil was so clean, easy to handle, and far less hazardous. It's funny now that I think about it, but the Chief once told me to stay “away from that nuclear stuff" because in his opinion it was "too dangerous." He ever had the opportunity to learn about nuclear power and was relying on myths and rumors perpetuated by the opponents of nuclear energy. I learned a great many things from Chief Taylor and we kept in touch for years, but that was one piece of advice I decided to ignore as I learned more about the benefits of nuclear energy.

In the years since then, commercial ship propulsion has continued to evolve from steam turbines to large diesel engines or gas turbines. Steam plants are complex machines with miles of cables, thick steel pressure vessels and pipes that must withstand thousands of pounds per square inch of internal pressure. There are also thermodynamic limitations to how efficient steam turbine plans can be even under ideal conditions. Diesel engines and gas turbines cost less to operate because the engines themselves cost less, they are simpler to maintain and operate, require fewer people, and burn fuel more efficiently. It was only a matter of time before diesels engines and gas turbines replaced oil fired steam turbines for commercial ship propulsion.

The Future of Nuclear Reactor Designs

All this brings me back to my original point: water cooled reactors are wonderful machines that will continue to serve us well for decades to come. But just as steamships switched from coal to oil, and then from steam turbines to diesel engines and gas turbines, the time has come for the next generation of commercial nuclear energy facilities. The next logical step is small modular gas cooled reactors. These new reactors will use modular construction techniques that will lower production costs, improve quality control and enable investors to scale up capacity more gradually. Gas cooled reactors coupled with gas turbines will improve thermal efficiencies that will produce more electricity for a given size of reactor.

New fuel types like non-metallic ceramics and liquid thorium will make it virtually impossible for rogue nations to divert civilian fuel to weapons programs, and these new fuel designs will revolutionize the industry because they will eliminate the risk of meltdowns. These improvements will reduce the complexity of nuclear energy facilities, and in doing so will reduce construction costs. All of these characteristics will reduce the risk to investors and will thus increase the rate at which small reactors will be deployed.

The people who oppose nuclear energy, including some who compete directly with nuclear energy for market share know all this and they will work to slow down these advancements. There is a major fly in the ointment: our government is standing in the way of these small reactor innovations. Our regulatory framework and licensing processes are unfair and are NOT up to the challenge. The fee structures for approval and licensing are biased against small reactors, and the Nuclear Regulatory Commission has not demonstrated a willingness to devote sufficient resources to move towards evaluating these new safer designs because it will require them to depart from their established comfort zones.

Other stakeholders are also slowing innovation. For example, the timeline the Dept of Energy has published for deploying Generation VI reactors is far, far too long. They estimate it will take 15 to 20 years to build the first demonstration plant! In reality most of the engineering challenges have already been solved and proven in the real world. The DOE needs to take the project away from the research community and give it to engineers with orders to build one!

The first nuclear submarine was designed, built, and launched just 13 years after the first controlled nuclear chain reaction, and the first commercial nuclear plant was designed and built in a matter of months, not years, without the benefit of more than 50 years of experience and modern computer aided design techniques. Those engineers used slide rules and hand calculations where today's engineers and scientists have more computing power on their desks than existed in the entire world in 1950.

We need a national commitment to move forward rapidly and decisively on small gas-cooled modular reactors with determination and leadership. We need to put aside the politics of fear and favoritism and focus on the truth inherent in real world experience and sound science. I am not suggesting we throw safety to the wind; on the contrary, the potential consequences of inaction or slow action are far greater than the risk of moving forward with urgency.

You may think I am asking for too much, but if we don't demand change, and demand it loudly, then this natural evolution will be too long in coming. We'll miss the opportunity to enjoy the results we need now to eliminate air pollution and reduce reliance on fossil fuels. This change will be as natural an evolution as the switch from sail to steam, and we need leadership to get us there as quickly as possible!

Have a great week!

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