New life for old nuclear plants

The Chicago Tribune ^ | September 19, 2004 | Robert Manor

[Willie Green]

Despite concerns over safety,
including uncertainty over how long the reactors will be able to keep running,
some licenses have been renewed through 2040

FORKED RIVER, N.J. -- Obscured by scrub trees and unkempt shrubs not far from the Atlantic Ocean, the Oyster Creek nuclear plant, which has generated electricity since Richard Nixon became president in 1969, is looking at a prolonged life, as regulators allow utilities to run reactors decades longer than first anticipated.

Driven by demand for cheap power, utilities are seeking to keep existing reactors operating until as late as 2040 and beyond. Regulators have approved license extensions for aging nuclear plants across the country, with more to come.

Which raises the question, how long can a nuclear plant run safely?

[Willie Green]

Westinghouse nuclear plant design OK'd (for China, not U.S.A.)

[sten]

Well, I for one am keeping an eye on China and their pebble bed reactors. They believe they have a new design that would be cheaper and safer to run. If true, we could be using cheap, abundant, and safe nuclear energy in the future. (look to this month's issue of Wired for an article on it)

[woofer]

some licenses have been renewed through 2040

This "news" is so twenty years old. Life Extension was first done at the ComEd Zion plant in the eighties.

Xcel's Prairie Island 1 and 2 plants bought new safety related switchgear in 1990 with the manufacturer committing to support into 2040.

Sheesh.

[Willie Green]

Did you actually read the article?
Despite what might be perceived as a slight anti-nuke bias, it DOES contain some good detailed information regarding the older designed power plants. I particularly don't care for the "elevated pools" used to store spent fuel on some of the GE plants. IMHO, it's all the more reason to go ahead with Yucca Mountain. (It would also be wise to start reprocessing and recycling the spent fuel, rather than burying it, as well.)

[Whispering Smith]

I think sustained bombardment by the products of a nuclear reaction may affect the structure of the metals forming the reactor vessel and other components within the reactor compartment. Therefore, it might be prudent to review a twenty year old decision every once in a while.

[chimera]

I think sustained bombardment by the products of a nuclear reaction may affect the structure of the metals forming the reactor vessel and other components within the reactor compartment. Therefore, it might be prudent to review a twenty year old decision every once in a while.

Embrittlement of mild steel by fast neutron bombardment is a well-understood phenomenon. To track this, power reactors are designed with surveillance capsules placed within the pressure vessel which contain test specimens in ASTM-standard geometries made of the same, original steel used to fabricate the pressure vessel. Every so often one of these is pulled and the specimens tested for, among other things, embrittlement. I've done dozens of these and can tell you that, if there is any trend at all to be found in the data, it is that embrittlement is proceeding more slowly than anticipated. Some of the neutron-induced damage can be annealed out using fairly common procedures (i.e., slow heatup of the vessel during restart from a refueling outage). That is one reason why those involved in plant life extension work have been able to move the process along fairly smoothly.

[Whispering Smith]

Thank you for this information. Now, how about the impact of water chemistry on materials? I seem to recall turbine blades disolving due to the impingement of water chemistry hyped steam. Any impact up stream on the primary loop?

[chimera]

Water chemistry on the primary side is pretty tightly controlled. It is monitored closely. The plant technical specification generally require precise control of the primary coolant purity.

Remember also that components that form the fuel and pressure boundaries on the primary side are highly corrosion-resistant. The pressure vessel has a stainless steel liner and the fuel cladding is zircalloy for LWR systems. With those materials, you initially form a very thin oxide layer and then not much else happens for a long time.

On the secondary side, especially steam generators for PWRs and, further downstream, turbines and condensers, sure, you can have some wear and tear. But those kinds of things are expected and manageable. I don't know of many large-scale, high energy steam systems that won't have such issues at some point in their operational lifetime. But you plan for them and manage the issues as they arise. Nothing unusual about that.

[Robert A Cook PE]

South Africa is already buiding a pebble bed plant now.

[Whispering Smith]

It is the same water in both loops. Make up feed comes from the same source as the make up primary coolant.

[chimera]

But the loops are isolated during operation. Water chemistry requirements are not the same depending on where the fluid is used. Check the plant tech specs. Boronation, for example, in PWR primary loops, is not done on the secondary side. You don't want boric acid going through turbines. Similarly, on the condenser feedwater, you don't want some of the things in the primary and secondary loops blowing down through the cooling tower. While primary water source may be common (in the end it all is anyway), the "fate" of the fluid once it enters the various loops is quite different. In any case, things affected by corrosion are almost exclusively on the secondary side. Things like steam generator tubes, pump impellers, etc. Replacement of those is certainly manageable using standard techniques. The only thing I ever dealt with in failure analysis on the primary side were some fuel assembly spacers, and some flow separation rings in the downcomer region. The plant had a loose parts monitor and those were picked up pretty quickly. It caused an unscheduled outage which is never fun but better to play it safe.

On the secondary side, I've dealt with a plethora of corrosion issues. The worse was a corrosion cracking failure of a holdup tank on a condensate polisher loop. That was nasty from a decon viewpoint but otherwise was pretty straightfoward.

Bottom line, I think radiation effects are probably the limiting factor on the primary side component lifetimes. I came up with a design for an NSSS with all replaceable components, but never got any backing on it. Politics, regulatory climate, and financing paradigms are all stacked against such things.

[Whispering Smith]

If oil stays at $50 a barrel you may find yourself and your plant back in business.

[chimera]

You're correct in that economics more than technology will likely be the deciding factor. Doing something to reduce the use of petroleum-based fuels in the transport sector is the number one thing we can do to be less dependent on foreign sources of crude oil. Hydrogen-based energy systems is one way to do that but the economics aren't there right now, but they might be if current trends continue. Electric substitution is another if we can do something about storage battery efficiency/lifetime.

[Whispering Smith]

I do not know what the ratios between and among hydroelectric, nuclear, natural gas, oil, coal, and other sources of electrical power are. However, in my opinion, fixed sources of power should be based on hydroelectric, nuclear, or coal. Natural gas should be used for domestic purposes (stoves and furnaces) and petroleum should be used for mobile requirements like automobiles, ships, and aircraft. However, capital ships should be nuclear powered. I'll leave it to the Navy to determine what is a capital ship.

[chimera]

Not a bad mix of sources. Baseload electricity should be generated by an intense source that has high availability and can give you strong performance on capacity factor. Nuclear is tough to beat on that score. Coal isn't bad either although if air quality standards are tightened then pollution dispatching may become more common (taking plants offline during periods of weather conducive to degraded air quality).

Natural gas absolutely should not be used in utility boilers. The one good idea Amory Lovins has ever had is the notion of matching, where possible and practical, the energy source to its end use. Gas is transportable and can be effectively utilized at its endpoint, which are domestic applications. Burning it up in central power stations to make electricity is lossy and is not an efficient use of a deletable resource.

The Navy has made the decision to use nukes only on carriers and submarines. Submarine use makes sense for the purposes of range and stealth. They evidently feel that on surface ships it's just not cost effective on units smaller than a carrier. So, kiss those nuclear-powered guided missile cruisers goodbye. Gas turbines are going into those.

Hydropower? I think the wackos are going after those next since they've pretty well halted new construction of nuclear and coal plants, as well as oil refineries and almost any other large-scale industrial facility. Time was that the wackos were talking up small-scale, low head hydropower as a way to develop distributed power sources. Now they're blowing those up in the name of restoring streams to their "natural state". After they blow those up they'll go after the big boys. There was a group out west agitating to blow up the Glen Canyon dam. I'm convinced they have something against electricity itself, kind of like the Luddites did in the 19th century, when they warned people not to go into rooms lighted by electric lamps because the electricity would jump out of the wires and kill them.

[Whispering Smith]

I got it from a guy named Rickover.

[chimera]

Ah. Did he "interview" you?

[Whispering Smith]

No, it is from his Congressional testimony in 1973 or '74 concerning TRIDENT, 688's, CVANs, and CGN's. There were always McNamara residual staffies on the Hill pushing "cheaper" oil fired ships and craft.

[chimera]

Then there was Jerry Brown the one year he was running for President, talking to the workers in Groton about how he would have them stop building nuclear subs, but, not to worry, he'd put them to work building diesel subs. Good old wacko Jerry, trying to compete in a 21st century military environment with 1930s technology. A good example of a Chevrolet mentality shying away from a spaceship world.

[Whispering Smith]

I think it unfortunate that the Navy was unable to marry up the CGN hull with the AEGIS weapons system. What a CV battle group and ABM capability that would make today. Putting that system on DD963 hulls was a mistake. They couldn't go north in the winter. I suspect the AEGIS Project Manager had his hands full with the weapons system development and just couldn't risk dealing with ADM Rickover who was then (1970's) at the peak of his power with the Congress. Not the first time powerful personalities have screwed things up.