[OPINION] How nuclear power plants work: Hot monster piss from Morong

The following is the 24th in a series of excerpts from Kelvin Rodolfo’s ongoing book project “Tilting at the Monster of Morong: Forays Against the Bataan Nuclear Power Plant and Global Nuclear Energy.“

Nuclear power plants are strange monsters: offspring of crude steam engines that started in the industrial age, married to ultra-sophisticated technology that split the atom and obliterated Hiroshima and Nagasaki in 1945.

The wood and coal that powered 19^th century steam engines were largely replaced by oil and gas in the 20^th century. An early 20^th century refinement adapted the energy of hot steam to turn electric generators.

So, nuclear reactors just heat water into steam by splitting atoms, just like coal in old cowboy movies that “firemen” frantically shovel to run a train away from Indians.

Nuclear fission

“Fission” is just a synonym for “splitting.” Nuclei of some of the heavier elements like Uranium 235 are fat, clumsy, and unstable. A neutron can bombard one and split it into two smaller nuclei – for example, a Krypton 91 and a Barium 142 – plus three neutrons. Each of these neutrons can also split a U235, releasing a barium, a krypton, and three more neutrons, in a chain reaction.

In an atomic bomb, enough U235 is suddenly clapped together into a “critical mass” that unleashes so many neutrons that they start an uncontrolled chain reaction that builds up to an explosion.

To prevent such explosions in a reactor, extra neutrons are absorbed with control rods that commonly contain Boron 10. When a Boron 10 nucleus absorbs a neutron, it usually splits into stable Helium 4 and Lithium 7 nuclei, without new neutrons. Sometimes, however, it splits into two Helium 4 and a Tritium atom, a heavy Hydrogen isotope. In future Forays we deal with Tritium, a seriously radioactive pollutant.

The pressurized water reactor

Here is how BNPP would work. If you can, watch this video version. (The first video is of a boiling water reactor, but that’s not what BNPP is. Watch the second video.)

The system has two separate, closed loops of flowing water. A primary loop, here colored orange (for very hot) and yellow (for still hot), cycles through the nuclear reactor vessel to absorb its heat. It is heated to 500°C or so, but prevented from boiling by enormously pressurizing it, to about 2,300 pounds per square inch. It is piped down through a secondary (blue) circuit of water.

This second circuit has three parts: a steam generator, a turbine chamber, and a condenser.

In the generator, heat from the primary circuit makes water into steam.

The steam flows up and into the turbine, making it spin. That, in turn, spins an electric generator, powering a community.

After passing through the turbine, the piped steam enters the condenser, which cools it back into liquid water and pipes it back into the steam generator, completing the cycle.

What cools the steam in the condenser back into water? A third, but open, circuit of water. Its intake and outlet pipes end in the blank corner next to the condenser in the picture.

That empty corner represents a river or ocean source for water to pass through the condenser to cool it, and to receive it back. For BNPP, the ocean. That is why BNPP was built on the coast.

BNPP-heated water is a great concern for this Zambaleño, friend of Olongapo City and Subic Bay Metropolitan Authority, and marine scientist.

To keep BNPP cool

An important fact about nuclear energy, embarrassing to both scientists and engineers, is how wasteful of energy it is, as wasteful as coal-fired plants! Only about one third of all the energy it generates actually becomes electricity. The other two-thirds? Waste heat, plus the energy to dump it into the environment, where it causes serious damage.

To cool a pressurized-water reactor, 1.3 to 3.3 million cubic meters of water must be passed through its condenser every day. Our tropical waters are warm, and so BNPP would need more cooling water than elsewhere.

Meaninglessly huge numbers, 1.3 to 3.3 million cubic meter – but imagine standing by a canal of reasonable size. Every second you watch, 38 cubic meters of heated water rush past you.

The South China Sea is not simply a giant bucket of water from which BNPP could suck great volumes of cooling water, heat by about 14°C, and harmlessly dump back. Its surface waters respond with beautiful intricacy to the annual changes in the seasonal monsoonal winds.

Gyres tens of kilometers in diameter form migrate lazily westward, and dissipate over many months. In this picture, derived from Chinese satellite data from a single August day in 2004, gyres with blue rings are turning slowly counter-clockwise; those with red rings turn clockwise. The 3-dimensional insert shows how gyres extend deeply to the sea floor.

The Northwest Luzon Coastal Current flows northward, pushed by Southwest Monsoon winds to its maximal speeds, measured at almost 2 kilometers per hour by UP Diliman scientists in August 2017.

The Northeast Monsoon winds push the north end of the coastal current back, shortening and weakening it. Its south end also shrinks; there, flow diminishes and even reverses direction during those winter months.

The sea’s living organisms are adjusted to this complex ecosystem. How would the influx of hot water affect them and the ocean waters they live in?

The impact on the ocean of BNPP cooling water

Heated BNPP water would flow north fastest in the summer, past Bataan, Zambales, Pangasinan, and the Ilocos provinces. Some might join the major Kuroshio Current, a matter of concern for Taiwan and Japan. During amihan, it would stagnate and pool, awaiting the renewed northern push of the next habagat.

Would BNPP’s discharge carry radioactive contaminants? How much would enter Subic Bay and Lingayen Gulf? How would regional fishing, transportation, commerce, industry, and tourism be affected?

Perhaps most importantly: what would the heated water do to the coastal environment and organisms?

The interested reader can access a detailed, horrifying account of “How the Nuclear Power Industry Destroys Endangered Marine Wildlife and Ocean Habitat to Save Money” by the Nuclear Information and Resource Service, here.

Countless billions of microscopic organisms – the base of the marine food chain – are sucked into the condenser and destroyed. Small fish and other organisms are scalded or pulverized into sediment that clouds the discharge, which denies light and oxygen for plant and animal life on the seafloor.

US government agencies charged with protecting the marine environment from industrial abuse are often too lax: “… the nuclear industry’s needs almost always prevail over the interests of marine life…”

Would the Philippine government do any better?

And what would happen to BNPP if the flow stopped for any reason?

Spent fuel pools

Water has to be piped through the plant for another reason. After a few years in the reactor, uranium fuel assemblies weaken and have to be replaced. But they are still intensely radioactive and put out a lot of heat – more of that wasted 2/3 of the energy, yes?

The used fuel assemblies must be kept in cooling ponds for years. Accidental stoppage of the flow of water to keep the ponds cool is a nightmare, almost experienced at Fukushima in 2011.

We will explore a potential similar accident at BNPP in Foray 25. – Rappler.com

Born in Manila and educated at UP Diliman and the University of Southern California, Dr. Kelvin Rodolfo taught geology and environmental science at the University of Illinois at Chicago since 1966. He specialized in Philippine natural hazards since the 1980s.

Keep posted on Rappler for the next installment of Rodolfo’s series.

[OPINION] How nuclear power plants work: Hot monster piss from Morong

Nuclear fission

The pressurized water reactor

To keep BNPP cool

The impact on the ocean of BNPP cooling water

Spent fuel pools

Previous pieces from Tilting at the Monster of Morong:

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