San Onofre update 4/12

There is very little actual news to report yet; the NRC Chairman has toured the plant, and a brief report of this trip is available on the NRC's blog. Click here to read that report.

Far more interesting is the fact that apparently SoCal Ed has awakened to the need for direct approach to the public and the website I've just found which is attached to the SoCal Ed site for SONGS (San Onofre Nuclear Generating Station) is proof. The website is actually pretty impressive; it's located at "songscommunity dot com" and the entry page is found by clicking here.

Of great interest is this page, which is called "Just the Facts." This tells why this new website has appeared, gives some answers to questions and really drives home some of the real answers to questions commonly asked by those who don't know much about nuclear energy.. and as a result, it also squashes mistruths told by anti-nuclear opponents. This page is a good playbook, if you ask me. It's accurate, fair, not too heavily loaded and probably exactly what SONGS and SoCal Ed need right now.

Not only is there a great deal of information available about plant work in progress (specifically pdf files describing steam generators) there's also a plant status box which will show status in real time. There's even a link to a version of the site in Spanish, which is a great touch.

This site, when combined with the original site (see link here) about SONGS makes the web presence for SONGS move up toward the top ranks. I am fairly well impressed by the new site and am glad to see how well it's done. I suggest everyone interested in pro-nuclear outreach give the new site a look.

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San Onofre 2 and 3 - the plants shut down now with steam generator problems - are Combustion Engineering PWR plants. San Onofre 1 was a Westinghouse PWR which operated for many years beginning in 1968. This plant is now totally gone, at least to the naked eye; see here. This link has an interesting photo showing San Onofre 1 in process of demolition. Here are two early photos of San Onofre 1 from APR's files.


The photo above is from WASH-1082, published in March 1968 and shows San Onofre 1 in the final stages of construction and testing - at least, it would appear so by the completeness of the plant but presence of many work vehicles around.


Above is an impressive night photo of San Onofre 1 from the cover (fully open, showing front and back) from the AtomFair '68 Exhibitor Program in the APR collection. Both photos enlarge when clicked.

(APR also as of this time has new photo editing software - readers should notice an increase in photo quality even over previous versions.)

9:40 PM Eastern Thursday April 12, 2012
ATOMIC POWER REVIEW

UPDATE: Af of Friday morning, there are reports from SoCal Ed that both plants are exhibiting the same kind of wear in their steam generator U-tubes, and that more damage has been found in tubes at No. 2 plant. A number of articles are out this morning; click here to read one. More details later as they're found.

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San Onofre S/G update 3/27

Thanks to a tip off from Dan Yurman, we have the following release from the NRC:

NRC Confirmatory Letter / San Onofre restart preparations

The information contained in this release from the NRC answers several of the questions we've been asking about the exact nature of the failures in the new Mitsubishi steam generators installed in the two operating San Onofre Nuclear Generating Station plants (originally manufactured by Combustion Engineering.) The briefest possible version is as follows:

-Tubes in the steam generators are vibrating.
-The vibration is causing rubbing against support and alignment structures for the tubes, and rubbing against adjacent tubes.

One might wonder whether the vibration is caused by water and steam flow on the secondary side (steam side) of the U-tubes, or if it is caused by flow not within desired parameters on the primary side (inside) or both. Clearly the exact cause is not known as I write this.

What's clear is that all the appropriate actions for S/G tube leaks have been taken up until this point, and that proper investigation continues. There is nothing particularly alarming or disturbing in the NRC's report. As I have mentioned before, steam generators have thousands of tubes (these have 9727 each) so that there is always substantial reserve to have tubes plugged - and many steam generators are in full, safe, daily operation with hundreds of tubes having been plugged over their lifetimes.

Permit a clumsy historical semi-analogy here. Many tens of thousands of steam locomotives used to travel the world's railways - and these often experienced leaking flue tubes. These were often hand rolled in place or else power rolled in the shop to stop leakage... but since locomotive boilers aren't that large, the flues aren't that large or heavy, and since the locomotive boilers weren't contaminated, and weren't inside a massive containment structure, replacement of flues was always done. With nuclear plant steam generators, there is no other option -- and never has been -- other than to permanently plug the U-tubes in place if they leak. This set of facts is not a surprise whatsoever, and excess capacity has been designed into plants from the very beginning.

Some media outlets are carrying interviews or pieces that make this issue sound catastrophically dangerous. I can assure you that it is not. What is more important is the allegation now being floated that massive U-tube rupture is possible, leading to a possible meltdown.

Would the designers of these plants, knowing the possibility (since the beginning, in the early 1950's, that is) of primary to secondary leakage NOT prepare for rupture of the tubes? The answer is yes ... but frankly, the also designed for fast primary coolant leak would lead to a loss of coolant far in excess, in terms of rate, than you'd see with even a major primary to secondary leak.. and that loss of coolant rate is also designed for by emergency makeup systems which can flood coolant (borated, in most plants) into the primary to keep the core covered and cooled. So, then, "experts" saying that the potential for primary to secondary leaks that can lead to meltdown on this plant are not telling the truth.

To be fair, primary to secondary leakage is a problem. It's one of the problems you expect you might have to deal with in a pressurized water plant. That's why detectors on the condenser air ejector vents are there in the first place! That's also why they alarm at a detected level far below that which would correspond to a serious primary to secondary leak. Further, monitoring of primary coolant inventory isn't that hard - compensated pressurizer level is a good clue. The point here is that you know if you're losing primary coolant to the secondary pretty quickly after it starts -- even with a small leak.

Closing for now, I'd like to point out that the NRC is clearly confident that the owner operator (Southern California Edison) is on top of the plan to make sure the plant is safe before restart. The communication between the NRC and SoCal Ed is clear, concise, accurate and realistic. The plan to make sure the causes of the U-tube vibrations are known and corrected before restart is clearly in progress. Knowing these things we can all be assured more now than ever that the real fundamental causes of this difficulty will be found and corrected prior to San Onofre 2 and 3 being restarted.

9:25 PM Eastern Tuesday March 27, 2012
ATOMIC POWER REVIEW

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Palisades - some general comments.

Over the last several months, I have received numerous questions about Palisades Nuclear Power Station which is located near South Haven, Michigan and which is presently operated by Entergy Nuclear Operations. I have until now declined to comment as most of the inquiry has concerned personnel issues, which are all too well described in the various NRC releases and findings which the press have seized upon. Since these things are well covered there has been no need to respond. However, a new allegation has arisen which is similar to one I confronted about a plant in Japan some time back. First, some background.

Palisades is a Combustion Engineering pressurized water plant which was ordered by Consumers Power in January 1966. According to an official Palisades press kit issued by Combustion Engineering and Consumers Power which I have here, Palisades was the first nuclear station in the United States that was not a "turn key" project contracted to a single firm; rather, Consumers Power contracted Bechtel Corporation for general consulting and engineering services, and the two firms, working closely, independently ordered all of the equipment required to construct the station. Original plans called for four identical units at the site, but only one was ever begun. This plan did lead to the single completed plant being referred to as "Palisades Unit 1" in some publications in the late 60's and early 70's which could lead to some confusion if this fact wasn't clearly described.

The reactor thermal output as built was 2200 MWt; the Westinghouse turbine generator at that reactor power produced 710 MWe of power although it was rated at 845 MWe maximum. The 2008 data for the plant are a reactor thermal power of 2565 MWt and a corresponding net electrical output of 778 MWe. Modern data from Entergy indicates a net electrical output of 798 MWe. When this plant was built, Consumers Power had been operating Big Rock Point Nuclear Plant since 1962 (this was a GE BWR/1 plant.) Consumers Power was also at that time building the Midland nuclear station, a two-unit Babcock & Wilcox plant that was never finished.

Palisades achieved initial criticality May 24, 1971 - about a year behind the original ambitious schedule. The plant first delivered power commercially on December 31, 1971 (both dates according to WASH-1203-73, US AEC 1973.) Like many other plants, Palisades had some initial problems that had to be ironed out but they weren't nearly as bad as those at some other plants built both before and after.

Palisades' earliest serious unplanned outage took place starting at about the middle of 1973 to repair leaks in "B" steam generator. The photo here, courtesy AP and which is an old AP Wirephoto, shows Palisades in October 1974 while undergoing testing after the year long outage. Notable is the addition of cooling towers - these were not a part of the original plant design which used only lake water for plant cooling. The Combustion Engineering - Consumers Power press kit (which is from early 1970) makes no mention of, and does not show, any cooling towers. Note the excavated area beyond the plant where the second unit would have been constructed.

Entergy bought this plant from Consumers Power in April, 2007.

So now we have a bit of background on Palisades - which I might add showed a very high capacity factor of 99% as recently as 2008. More recent problems have put the plant in a bad light, and local activist press has not helped. We now bring to focus the following commentary found on line:

"Palisades must be shut down"

This commentary needs some sober observation and reflection. This exact same kind of argument was brought up some time back concerning Genkai nuclear station in Japan. I conducted a VERY thorough description of reactor vessel embrittlement on Atomic Power Review at that time - and it's applicable here.

Genkai Reactor Vessel Embrittlement Discussion on APR

While much of the above discussion is targeted at Genkai, it's all generally applicable to Palisades and relative to the commentary I linked. Some points in the linked commentary:

-The NRC has never weakened safety regulations. When new analyses are made, then old ones which are less accurate are reconsidered. This process can both help and hinder relicensing processes for plants.

-No "old, degraded" reactors are operating. None exist.

-The phenomenon of PTS or "Pressurized Thermal Shock" was originally developed in the early 1980's after two incidents (one at Palo Verde, the other at Crystal River) gave evidence that there was a remote chance that the design basis accident causal mode known as brittle fracture (this being relative to the reactor pressure vessel) which had never happened even once could possibly be induced by a pressurized thermal shock sequence wherein a pressure vessel was taken from hot, critical normal condition through a rapid cooldown and depressurization, and then a rapid repressurization. The fear was that while no vessel had ever experienced the dreaded brittle fracture failure, so that this eventuality (still designed against) became highly unlikely, there could be some other chain of events that would essentially duplicate it but would be much less immediate, more nuanced, and harder to prevent. As it turns out, there were massive discussions about PTS in some quarters during the first half of the 1980's but as a practical matter later, much better knowledge of how pressure vessels age has lowered concerns... largely through the use of sample materials placed in high neutron flux areas inside reactors, which samples are then removed and tested exhaustively.

According to Gregory Myerson the NRC found a solution to any serious worry about PTS was to order alteration to the alloy used to fabricate reactor vessels and did so as early as 1971 - while monitoring any vessels built prior exceedingly carefully to ensure they don't pose any increased risk. To date, none has been identified.

The commentary then soars off into ridiculousness, with every incredible worst-case type assumption and scenario being topped by the next one. As such it's easily recognizable as anti-nuclear hyperbole and hype. But... what DID the NRC resident inspector really say?

Probably, the inspector wished to convey that neutron damage to a pressure vessel really consists of the displacement of atoms from their normal positions in the crystalline metal structure or lattice. This makes essentially gaps that are one atom wide. Not exactly the holes this commentary describes. Moreover, this damage is easily designed against by careful control of materials used in the pressure vessel, careful manufacturing and extremely generous allowance for the effect of the damage over decades so that even with embrittlement the vessel still behaves normally and can handle the original specified temperatures and pressures. Some plants have very old vessels which require some modification of the allowed rate that you can heat up or cool down the vessel - but this is normal for very old vessels, frankly. As mentioned in my Genkai article, so much monitoring and study is being done and has been done that vessel embrittlement is probably one of the most studied metallurgical phenomenon to come out of the whole history of nuclear engineering.

Left, reactor vessel and internals, Palisades Nuclear Power Station, as originally built.

Getting now to the present NRC findings - which have far more substance than the allegations of embrittlement - there will be a public meeting tomorrow night (February 29, 2012) that will likely gain some attention. Click here to read one article about the meeting. Click here to read another. I will be watching to see what comes out of these meetings and report on it here. It suffices to say that the personnel issues brought up seem to have more substance than any of the reactor vessel issues the activists are attempting to invent. It is those on which the attention must be cast.

Click here to view Entergy's page on Palisades.

9:50 PM Eastern Tuesday February 28, 2012
ATOMIC POWER REVIEW

NOTE: Some questions were received about San Onofre, in California, which also has Combustion Engineering plants whose (new) steam generators were found to be leaking very recently. These new steam generators were built by Mitsubishi in Japan, and so there is no direct correlation at all between the primary-secondary leaks at San Onofre and any other Combustion Engineering plant.

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San Onofre - Primary to Secondary leak

Unit 3 at California's San Onofre Nuclear Generating Station has experienced a primary to secondary leak in one of its steam generators. This kind of failure cannot be described as everyday or commonplace to the point of normalcy, but this kind of failure does happen frequently enough that there are widely known and standardized procedures to deal with it. This type of failure usually results in plugging the U-tube or tubes if multiple which are leaking in the steam generator. Since each generator has many thousands of tubes, plugging several or even dozens does nothing to the heat transfer from the primary to secondary and in no way makes the plant any more dangerous than it was before the leak occurred. Many plants have operated with dozens or hundreds of plugged steam generator tubes for many years.

Here is the text from the official NRC report:

MANUAL TRIP DUE TO A PRIMARY TO SECONDARY LEAK GREATER THAN 30 GAL/HR

"At 1505 PST, Unit 3 entered Abnormal Operation Instruction S023-13-14 'Reactor Coolant Leak' for a steam generator leak exceeding 5 gallons per day.

"At 1549 PST, the leak rate was determined to be 82 gallons per day. At 1610 PST, a leak rate greater than 75 gallons per day with an increasing rate of leakage exceeding 30 gallons per hour was established and entry into S023-13-28 'Rapid Power Reduction' was performed.

"At 1630 PST, commenced rapid power reduction per S023-13-28 'Rapid Power Reduction'. At 1731 PST, with reactor power at 35% the Unit was manually tripped. At 1738 PST, Unit 3 entered Emergency Operation Instruction S023-12-4 'Steam Generator Tube Rupture'.

"At 1800 PST the affected steam generator was isolated."

All control rods fully inserted on the trip. Decay heat is being removed thru the main steam bypass valves into the main condenser. Main feedwater is maintaining steam generator level. No relief valves lifted during the manual trip. The plant is in normal shutdown electrical lineup.

Unit 2 is presently in a refueling outage and was not affected by this event.

The licensee has notified the NRC Resident Inspector. The licensee has issued a press release.

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San Onofre 3 is a Combustion Engineering pressurized water reactor. The containment style at this plant is dry, ambient.

The steam generators on San Onofre 2 and 3 are however not original to the plants. These steam generators were manufactured by Mitsubishi Heavy Industries in Japan, and were installed as replacements for both plants' original CE steam generators.

There are now reports circulating fairly widely that NRC officials have noted excessive wear on a number of the steam generator U-tubes in San Onofre Unit 2, which is presently shut down for refueling. Clearly, with a tube rupture or leak having occurred in identical equipment while at power on the same site, a much deeper investigation will take place.

There are reports circulating that "a radiation leak has shut down the San Onofre nuclear plant." The cause of the shutdown was a primary to secondary leak, not a "radiation leak," whatever that is. There are reports that a small amount of radioactive material in gaseous form may have been released to the atmosphere. I am continuing to look into this - but NO threat to the public exists.

The plant is shut down, and the affected loop is isolated from the reactor.

Here is a view of a typical Combustion Engineering pressurized water commercial nuclear plant primary system - called typically the NSSS or Nuclear Steam Supply System. In the large steam generators seen at the sides, heat is transferred from the primary coolant (circulated through the reactor by large pumps, clearly visible) into the secondary water as the primary water passes through many thousands of small diameter tubes. On the outside of these tubes is the secondary water, which boils, turns to steam, and then powers the turbine generator and other plant equipment. If a primary to secondary leak occurs, then, it is possible for some radioactive material to enter the steam plant.

Having said this, ALL steam plants at nuclear stations are designed with this eventuality in mind and primary-secondary leaks through small holes, or even tube ruptures, have occurred many times before. When controlled properly (as at San Onofre) there is no risk to the reactor, or its cooling or monitoring.

Finally for now here is Edison International's press release:

SAN ONOFRE LEAK PRESS RELEASE - FEB 1

4:50 PM Eastern Thusday February 2, 2012
ATOMIC POWER REVIEW

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