August 27th, 2012

Nuclear power plants generate heat by bombarding "fissile" atoms (such as uranium-235) with neutrons. When the atoms are split, more neutrons are released, which then split other uranium atoms in a sustained "chain reaction." The heat energy released by this process is used to boil water to produce steam to turn a turbine which produces electricity.

The process is inherently dangerous, inherently dirty, and inherently very profitable -- if you don't have to pay the additional costs of: Accidents, cancers from routine releases, or the safe storage of the nuclear waste stream for thousands upon thousands of years. However, somebody will have to pay all these costs. Catastrophic, globally-impacting accidents are inevitable, as the world has seen four times in the last three decades: Three times in Fukushima and once in Chernobyl, with many "near-misses," many of which have been hidden from public scrutiny, and countless less serious -- but still very serious -- smaller accidents.

Every day a typical nuclear power plant operates, it generates about 250 pounds of "high level radioactive waste" which consists of:

* "Fission products," two of which are usually produced whenever a heavier uranium atom is split,

* "activation products," which are produced whenever a neutron is captured by a stable atom (such as in the millions of pounds of steel that are used at the plant),

* plutonium, which is created in copious quantities and can be used for making nuclear bombs, and

* "unburned" uranium ("burnup" is an industry term for nuclear fission. The nuclear fuel is not burned or chemically manipulated in any way.)

San Onofre Nuclear Generating Station really should be called San Onofre Nuclear Waste Generating and Storage Station. Currently over 1,400 tons of "used fuel" is stored on site at San Onofre. To grasp how vast a quantity that is, one has to consider the lethality of radioactive elements. A few millionths of a gram of plutonium for example, is enough to guarantee lung cancer if it ends up in someone's lungs. It can enter the lung as one "hot particle" or as millions of smaller particles. It's deadly either way.

Plutonium is approximately 200,000 times more deadly than uranium, and many fission products are even deadlier than that, pound for pound (or rather, microgram for microgram): Radioactive cesium, strontium, polonium, iodine, and many others.

Ever since January 2012 when recently-replaced steam generators at one of the two reactors at San Onofre sprung a leak, SanO hasn't been operating. It hasn't been generating waste, and it hasn't been generating electricity, either. The lights in Southern California have stayed on throughout the hot summer months, and the electricity grid is stable -- not counting the earthquakes. There is no need to restart SanO and plenty of reasons not to.

However, the utility company that owns and operates the plant is hurting for profits for its shareholders, and would desperately like to get San Onofre operating again. That may be impossible without somebody spending close to a billion dollars to repair the twin reactors. But who will spend that money? The utility would like it be the ratepayers, not the shareholders. The state regulators, the California Public Utilities Commission (CPUC), made the ratepayers pay -- and are still paying every month -- for the first set of replacement steam generators, at a cost of nearly a billion dollars. Since the almost-new parts have failed unexpectedly early, it will presumably cost about the same amount to restart the reactors again, plus the cost of replacement fuel for several years during the outage -- and plus the extra costs of not cutting so many corners and doing it right.

This is outrageous! The citizens of SoCal, one of the most beautiful places on earth, are put at great risk by San Onofre. It doesn't generate cheap power, it's the most expensive power in the world (when all the costs to society are taken into account). And it's obviously not reliable -- reliable "base load capacity" has always been a claim of the nuclear industry, even though capacity factors are rarely as high as with traditional gas, coal or oil power plants, let alone hydro power or many renewable alternatives. True, the wind doesn't blow all the time and the sun doesn't shine every day -- and lately, the rains don't even come -- but when those things do happen -- when the wind blows or the sun shines or the rains fall -- the energy sources are extremely reliable, and stored energy systems such as pumped water, flywheel, pressurized air, or even chemical processes (batteries) can give renewable energy systems virtually 100% uptime. Nuclear can NEVER achieve that; it has never even come close.

What went wrong at San Onofre last January is a classic tale of the abuse of power. It was the culminating event in a long series of missteps by the utility. Eager to replace approximately a billion dollars in parts prior to license renewal (so they could say they were ready and able to operate for another 20 years), the owner/operators redesigned crucial parts of the reactor that were failing prematurely. The parts, called steam generators, consist of nearly 10,000 very thin metal tubes inside a very large (the size of a school bus) container.

Inside the tubes is "primary coolant" directly from the reactor core. Outside the tubes (but inside the steam generator) is water which turns to steam as it rises. Both are normally closed, pressurized loops. A third open loop of sea water is used to condense the steam after it goes through the turbines. All three loops are fed by massive pumps which must continuously operate, using "offsite power". At San Onofre the pressure differential between the primary and secondary loops is about 1,000 pounds per square inch. The primary loop normally operates at about 2,200 p.s.i..

There are two steam generators for each of the two reactors at San Onofre, and all four steam generators were replaced within the last two years. All four have shown significant, unusual wear since then, and on January 31st, 2012, one of the tubes in one of the steam generators sprung a leak.

Since that day, San Onofre's owner/operators, Southern California Edison, have tried to come up with a plan to "safely" restart the reactor. Of course, they can never be operated safely, because many more things than just the steam generators can break catastrophically at a nuclear power plant, but ignoring that fact, as SCE does, SCE wants to at least run one of the reactors -- not the one that sprung a leak, that one's trashed -- at partial power, so they can make some money and, perhaps just as important to them, avoid an investigation by the CPUC of what went wrong (the CPUC has been so supportive of SCE's "need" to make a profit from San Onofre, that perhaps this was not a major concern, but it is always possible that an investigation would reveal something).

By state law, the CPUC is required to initiate an investigation after nine months of unavailability of a power source it regulates. Nine months will be October 31st for the reactor that sprang a leak, and a few weeks sooner, mid-October, for the other reactor, since it was already closed for upgrades (and refueling) at the time the other unit sprang a leak. Subsequent inspections showed all four replacement steam generators to be seriously worn and degraded.

But it's not just the premature wear that is the problem. It's the type of wear. Those nearly 10,000 tubes inside each steam generator have been vibrating uncontrollably and banging into each other in a cohesive and uniform -- and invariably very damaging -- coordinated pattern.

When the decision was made to replace the old steam generators with new ones (so that during license renewal in a few years, SCE could claim the reactors are "ship-shape") a large number of design changes were made -- at least three dozen significant changes.

The problem arose when they used a pair of computer programs to model the behavior of the fluids inside the steam generator. The incorrect mathematical calculations from one were carefully fed into the other, and everyone trusted the final computer output. It was off by approximately 300% to 400%.

In fact, much more steam was produced lower in the tubes than expected, so that the mixture of steam and water was nearly all steam at the top of the U-shaped tubes. Steam doesn't dampen vibration nearly as well as water does because it's about 30 times less dense.

Perhaps the problem could have been avoided if the steam generator replacement project had been accomplished through the appropriate regulatory channels, with public hearings about the exact design changes and a more careful scrutiny by the Nuclear Regulatory Commission.

But instead, SCE chose to present the new steam generators as "like-for-like" replacement parts, which was hardly the case, and slipped it through with minimal regulatory oversight at the federal level, where "safety" decisions are made, and even less at the state level, where rate decisions (and little else) is decided. They were given about $670 million of ratepayer money to pay for the project. Properly submitting the new design as a truly new design for full and open regulatory approval would have required many more public hearings, but SCE said they had merely "improved" the alloy of the tubes, not even mentioning the fact that the new alloy is 10% less efficient than the old, leading them to add hundreds more tubes, and to make each of the tubes a little thinner, and to pack them all a little closer together: A recipe for the end result. The NRC, never an agency to push hard against ANY utility, went along with the "like-for-like" assessment.

Where are we today? Unit 1 was closed for similar early wear problems in the steam generators in the early 1990s. Of the two remaining reactors at San Onofre, called Unit 2 and Unit 3, the one that actually leaked (Unit 3) apparently cannot be restarted at all unless the steam generators are replaced. Even SCE has all but admitted it, and "layoffs" of 730 employees, about 1/3 of their workforce, were recently announced and are expected to occur before the end of the year.

SCE has been saying for several months that they would like to restart the other reactor at reduced power. But despite much talk, SCE has still not submitted a restart plan to the NRC. They cannot seem to find the "sweet spot for SanO" wherein they can assure the NRC that they can cool the reactor with only one steam generator, should one of them fail, as happened in January. Running at reduced power is one thing, but what if something goes wrong? So SCE appears to be between a rock and hard place, although there is talk of design changes which they are making and which -- again -- will avoid full public scrutiny before being approved (and they surely will be approved) by the NRC: The new changes would avoid full public scrutiny by being considered minor changes to the current design!

There is only one logical, cost-effective, and safe solution: Keep San Onofre shut down forever. What could possibly be gained from rebuilding it and restarting it? It will just generate more waste -- 250 pounds per day per reactor. Nearly a ton per week for the two reactors combined. There still is no safe storage place for the "spent fuel" (used and very radioactive reactor cores). "Dry Casks" containing them will just keep piling up on our coastline as they do now. Meanwhile, an accident could require the PERMANENT evacuation of all of SoCal? It's not worth it to anybody -- except, and even this is now in doubt -- the shareholders of SCE and its parent company, Edison International.

In Japan, where three of the four catastrophic meltdowns mentioned in the beginning of this article occurred (at Fukushima in March, 2011), nearly every reactor has been shut down, and the public has been protesting night and day, week after week to keep them closed. They've seen first-hand what happens when a reactor melts down: People are relocated, property is lost, crops are poisoned, and health problems multiply. Farm animals were cruelly abandoned to their fate (ropes the Japanese put on calves eventually cut into their mouths and slowly killed them, if they didn't die of starvation in their pens or barns first). Pets were left to open their own cans of pet food, when people were told they would be allowed to return after a few days and to leave their pets, but now it's clear it will be many generations before anyone can return to many parts of Fukushima.

None of this had to happen, and it doesn't have to happen here. San Onofre doesn't have to become our Fukushima -- but it nearly did! If we keep SanO closed, we'll still have to worry about the spent fuel -- that's a huge problem and can also result in a catastrophic release of radioactive poisons. But at least the problem won't be growing, and at least there won't be any reactors to melt down, which are much more precarious. Time is the only thing that renders radioactive waste safe.

San Onofre should be decommissioned (dismantled). It should never be allowed to restart.

ULTIMATE WISDOM – San Onofre Watergate
I agree with you 100% ACE Hoffman

The options are as followa:
1. Award the Sole Source Contract to World's Premier Nuclear Company, Westinghouse to Rebuild both the RSGs like Palo Verde Nuclear Generating Station CE RSGs. It will cost EIX Share Holders at least One Billion Dollars (They won’t agree to Pay) and continued Public Disapproval, Mistrust and Fears (Not Recommended), OR
2. Decontaminate, decommission and dismantle both defective RSGs. EIX already have the funds from Rate Payers, and
3. Give the Contract to SONGS PMO/Mission Energy to procure and install 4-500 MW Gas-Fired Units in Mesa/Lot 4. It will cost 2 Billion Dollars.

Bill, Friends of the Earth, Professor Dan Hirsch, Rate Advocates, and San Clemente Green will assist EIX/SCE to get a New License approved from the Honorable Governor Jerry Brown and other Pertinent Authorities. Southern California Gas Company can supply natural gas to these units.

Frankly, San Onofre has the worst record of addressing nuclear personnel/nuclear safety concerns (e.g. Billon Dollars Wasted Steam Generators, Fire/Safety, Lack of Station Ownership of Emergency Preparedness, Poor Maintenance, Inefficient Work Control, Uncontrolled Configuration Control, Lack of Adherence to Convoluted/Complicated Procedures, Unhuman Attendance Policy, Low Employee Morale, Harassment, Retaliation, Intimidation, Demotions, Be Here Now, Cyber Security Program, Lack of Solid Team Work & Alignment between Divisions, etc.). I can personally attest to all of this, because I was there for 15 years. When I tried to help the management to address these concerns, you would not believe what they did to me. Finally I said, Thank You, and I Resigned.

Like One SONGs Worker says, “These Profit Driven Hungry Tigers are running San Onofre like a “Nazi Concentration Camp.” The present SONGS Management Structure does not have the capability/ability to Operate Nuclear Units and address these personnel/nuclear safety concerns. Existing SONGs employees with New Reformed/Humble Management can be retrained to operate these Gas-fired Units in an efficient and cost-effective manner. Public, Rate Payers, EIX Share Holders, Workers, NRC, CPCU, Workers, San Clemente Green, Friends of the Earth and News Media will be happy. Humans have only have one life to live. SONGS does not give the appearance of a Democratic and Civil America. SONGS Retaliatory Managers have to be taught to treat the workers with dignity and respect. Every SONGS Worker has a Constitutional Right to live in harmony and peace.

NRC AIT Report reveals SONGS Replacement Steam Generators Watergate

NRC AIT report is very conflicting, biased and inconclusive. It appears that NRC did not carefully “Scrutinize and Read between the Lines” the documents submitted by SCE/MHI and did not use a “Critical Investigative Attitude” to question the SCE’s Self-Claimed World Leading Steam Generator Experts to determine: (1) What these SCE Experts were dreaming during the preparation of SCE design and performance specifications SO23-617-1, doing during MHI Manufacturing of 21st Century Magic Radioactive Steam Producing Machines and Sleeping during validation/approval process of MHI Documents/computer codes, (2) How did SCE Experts/MHI missed the benchmarking of PVNGS RSGs, the largest CE RSG in the world, (3) Where did all the claims of challenges, rewards and innovative design of SCE/MHI of team work go wrong, and (4) Were the SCE Experts and Managers under time and financial pressure so that they selected a low-cost manufacturer, which did not have the experience of building such large CE Replacement Steam Generators. The AIT reports absolves SCE Experts of all the blunders and blames MHI for all the failures, which resulted in the San Onofre Replacement Steam Generator (RSGs) Watergate and Billion Dollar Rate Payer Fiasco.

A review of the NRC report indicates that the AIT concluded that SCE’s 10 CFR 50.59 evaluation regarding the replacement of the original steam generators did not affect the current licensing basis to the extent of needing prior approval from the NRC as required by 10 CFR 50.59. The NRR technical specialist reviewed SCE’s 10 CFR 50.59 evaluation and found two instances that failed to adequately address whether the change involved a departure of the method of valuation described in the updated final safety analysis report. SCE’ posting on the internet stated that Screening and 10 CFR 50.59 Evaluations for the replacement steam generators were inspected and reviewed by the NRC prior to the recent discovery of the tube wear issues with no findings with respect to 10 CFR 50.59.” Based on a review of the above evidence, it appears that the NRC accepted Edison’s 10 CFR 50.59 Screening, Evaluations and supporting documents without due diligence, independent analysis and violating its own rules.

NRC AIT Report Page 56 further states, “Based on the cause evaluation and corrective action plan, SCE determined that the best solution to prevent tube-to-tube wear was to conservatively plug and stabilize the affected areas. By taking the impacted tubes out-of-service, SCE determined that this should reduce the potential for localized fluid velocities reaching critical velocity. In addition, in order to ensure sufficient margin to preclude the onset of fluid-elastic instability, SCE determined that reactor power would also have to be reduced. At this time SCE is still developing additional corrective actions to prevent tube-to-tube wear. The actions have not been finalized and no determination has been made concerning the appropriate power level. The NRC has not made any conclusions on the proposed corrective actions. Once the corrective actions have been finalized, they will be inspected as part of the Confirmatory Action Letter follow-up inspection.” It is covering up for its own mistakes relying on SCE Cause evaluation and blaming MHI for all the Mistakes.



NRC AIT Report Page 56 further states, “Based on the cause evaluation and corrective action plan, SCE determined that the best solution to prevent tube-to-tube wear was to conservatively plug and stabilize the affected areas. By taking the impacted tubes out-of-service, SCE determined that this should reduce the potential for localized fluid velocities reaching critical velocity. In addition, in order to ensure sufficient margin to preclude the onset of fluid-elastic instability, SCE determined that reactor power would also have to be reduced. At this time SCE is still developing additional corrective actions to prevent tube-to-tube wear. The actions have not been finalized and no determination has been made concerning the appropriate power level. The NRC has not made any conclusions on the proposed corrective actions. Once the corrective actions have been finalized, they will be inspected as part of the Confirmatory Action Letter follow-up inspection. Once again, it appears that NRC is “Sleeping on the Wheel” and waiting for SCE Steam Generator Experts to finalize the corrective actions, so NRC can once “Rubber Stamp” the “Catastrophic Corrective Actions”, which can this time lead to another Fukushima in “Southern California San Onofre EPZ Residents Backyards.”

NRC AIT Report reveals SONGS Replacement Steam Generators Watergate

NRC AIT report is very conflicting, biased and inconclusive. It appears that NRC did not carefully “Scrutinize and Read between the Lines” the documents submitted by SCE/MHI and did not use a “Critical Investigative Attitude” to question the SCE’s Self-Claimed World Leading Steam Generator Experts to determine: (1) What these SCE Experts were dreaming during the preparation of SCE design and performance specifications SO23-617-1, doing during MHI Manufacturing of 21st Century Magic Radioactive Steam Producing Machines and Sleeping during validation/approval process of MHI Documents/computer codes, (2) How did SCE Experts/MHI missed the benchmarking of PVNGS RSGs, the largest CE RSG in the world, (3) Where did all the claims of challenges, rewards and innovative design of SCE/MHI of team work go wrong, and (4) Were the SCE Experts and Managers under time and financial pressure so that they selected a low-cost manufacturer, which did not have the experience of building such large CE Replacement Steam Generators. The AIT reports absolves SCE Experts of all the blunders and blames MHI for all the failures, which resulted in the San Onofre Replacement Steam Generator (RSGs) Watergate and Billion Dollar Rate Payer Fiasco.

A review of the NRC report indicates that the AIT concluded that SCE’s 10 CFR 50.59 evaluation regarding the replacement of the original steam generators did not affect the current licensing basis to the extent of needing prior approval from the NRC as required by 10 CFR 50.59. The NRR technical specialist reviewed SCE’s 10 CFR 50.59 evaluation and found two instances that failed to adequately address whether the change involved a departure of the method of valuation described in the updated final safety analysis report. SCE’ posting on the internet stated that Screening and 10 CFR 50.59 Evaluations for the replacement steam generators were inspected and reviewed by the NRC prior to the recent discovery of the tube wear issues with no findings with respect to 10 CFR 50.59.” Based on a review of the above evidence, it appears that the NRC accepted Edison’s 10 CFR 50.59 Screening, Evaluations and supporting documents without due diligence, independent analysis and violating its own rules.

NRC AIT Report Page 56 further states, “Based on the cause evaluation and corrective action plan, SCE determined that the best solution to prevent tube-to-tube wear was to conservatively plug and stabilize the affected areas. By taking the impacted tubes out-of-service, SCE determined that this should reduce the potential for localized fluid velocities reaching critical velocity. In addition, in order to ensure sufficient margin to preclude the onset of fluid-elastic instability, SCE determined that reactor power would also have to be reduced. At this time SCE is still developing additional corrective actions to prevent tube-to-tube wear. The actions have not been finalized and no determination has been made concerning the appropriate power level. The NRC has not made any conclusions on the proposed corrective actions. Once the corrective actions have been finalized, they will be inspected as part of the Confirmatory Action Letter follow-up inspection.” It is covering up for its own mistakes relying on SCE Cause evaluation and blaming MHI for all the Mistakes.



NRC AIT Report Page 56 further states, “Based on the cause evaluation and corrective action plan, SCE determined that the best solution to prevent tube-to-tube wear was to conservatively plug and stabilize the affected areas. By taking the impacted tubes out-of-service, SCE determined that this should reduce the potential for localized fluid velocities reaching critical velocity. In addition, in order to ensure sufficient margin to preclude the onset of fluid-elastic instability, SCE determined that reactor power would also have to be reduced. At this time SCE is still developing additional corrective actions to prevent tube-to-tube wear. The actions have not been finalized and no determination has been made concerning the appropriate power level. The NRC has not made any conclusions on the proposed corrective actions. Once the corrective actions have been finalized, they will be inspected as part of the Confirmatory Action Letter follow-up inspection. Once again, it appears that NRC is “Sleeping on the Wheel” and waiting for SCE Steam Generator Experts to finalize the corrective actions, so NRC can once “Rubber Stamp” the “Catastrophic Corrective Actions”, which can this time lead to another Fukushima in “Southern California San Onofre EPZ Residents Backyards.”

SONGS Engineers did not benchmark the difference between the SONGs and PVNGS RSGs U-Tube Bundle Design. As a Part-Owner of the PVNGS, SONGS World Known Steam Generator Experts probably had access to all the PVNGS RSGs Westinghouse proprietary documents. As a Part of Industry Benchmarking, they should have reviewed ALL these documents. If SONGS Expert Engineers had used Due Diligence and Critical Investigative & Questioning Attitude, they would have avoided Billion Dollar San Onofre Replacement Radiation Steam Generator Nightmare, Rate Payer Anger and Frustration and Embarrassment for NRC, CPCU, EIX, SCE and MHI.

Root Cause for Tube Damage - Difference between SONGS and Palo Verde Upper U-Bundle Design – See Below - NRC and SONGS Root Cause are Silent on this issue

SONGS Design - MHI had expressed reservations regarding relatively small pitch to diameter ratio P/D = 1/0.75, Free span between Tubes = 0.25 inches). The high void fraction was identified from the results of Mitsubishi’s thermal-hydraulic model for the secondary side of the replacement steam generators. Mitsubishi considered that the combination of these two factors may have resulted in favorable conditions for in-plane tube vibration based, in part, on the results of recent studies in fluid-elastic instability.

PVNGS Design - The upper tube bundle support system (1) supports the horizontal tube spans against high velocity, two-phase cross flow, (2) permits an expanded vertical tube pitch (from 1.0 inch to1.75 inches) so as to promote free flow through the bend region and prevent low-flow dryout regions

SONGS Replacement Steam Generator U-Tube Bundle Design

NRC AIT Page 42 states, “The licensee’s bid specification required that the stay cylinder feature of the original steam generators be eliminated to maximize the number of tubes that could be installed in the replacement steam generators and to mitigate past problems with tube wear at tube supports caused by relatively cool water and high flow velocities in the central part of the tube bundle. Mitsubishi employed a broached trefoil tube support plates instead of the egg crate supports in the original design. In addition to providing for better control of tube to support plate gaps and easier assembly, the broached tube support plates were intended to address past problems with the egg crate supports by providing less line of contact and faster flow between the tubes and support plates, reducing the potential for deposit buildup and corrosion. Mitsubishi selected a u-bend configuration for the upper part of the tube bundle instead of the square bend design of the original steam generators based on its experience that u-bends were easier to fabricate and support and were easier to inspect. The team’s review of Mitsubishi design documentation for the anti-vibration bars indicates that Mitsubishi considered wear in the u-bend region as the most important issue affecting the anti-vibration bar design. Mitsubishi reviewed operating experience regarding wear in the u-bend region of replacement steam generators and trended the experience data as a function of steam generator manufacturer, tube packing arrangements (tube pitch, square versus triangular arrays), and steam generator size. The SONGS steam generators are relatively large, and Mitsubishi acknowledged that this and the tight tube packing geometry could affect wear experience. Mitsubishi stated that the SONGS replacement steam generator were designed to minimize these concerns by providing more support points with shorter spans in the u-bend region along with effective zero gaps between the tubes and anti-vibration bars during steam generator operation. Mitsubishi manufacturing was designed on achieving very small uniform gaps between the tubes and anti-vibration bars during assembly.”

NRC AIT Pages 19 & 20 states, “A review of NRC AIT Report indicates that MHI had expressed reservations regarding relatively small pitch to diameter ratio P/D = 1/0.75, Free span between Tubes = 0.25 inches), lack of experience in fabricating square bends and building such a large steam generator. The high void fraction was identified from the results of Mitsubishi’s thermal-hydraulic model for the secondary side of the replacement steam generators. Mitsubishi considered that the combination of these two factors may have resulted in favorable conditions for in-plane tube vibration based, in part, on the results of recent studies in fluid-elastic instability. The failure mechanism model also considered a fluid dynamic effect associated with the spreading of the tubes in the U-bend region during normal operating conditions. This effect was informally referred to as “flowering,” due to the characteristic shape in which the tube bundle spreads transverse to the plane of the u-bends at normal operating conditions. “Flowering” was described as the elastic deformation of the anti-vibration bar structure and the tube bundle in the U-bend region, as a result of thermal expansion and fluid dynamic pressure acting on the secondary side of the tubes. The deformation caused by the “flowering” effect was believed to result in multiple areas of no contact between the anti-vibration bars and the tubes, which minimized resistance to in-plane motion of the u-bend area of the tubes. Mitsubishi considered that the collective contribution of the factors described above resulted in conditions in the U-bend that were highly susceptible to excessive tube vibration. The in-plane vibration of the tubes in the U-bend region allowed direct contact between free-span sections of the tubes, resulting in the unanticipated tube-to-tube wear.”

Palo Verde 2 Replacement Steam Generator U-Tube Bundle Design
NUREG-1841, pages 34 & 35 Section 2.4.21 - Palo Verde 2

Palo Verde 2 has two recirculating steam generators designed by Combustion Engineering and fabricated by Ansaldo Energia. The steam generators were put into service in 2003 during RFO 11. Each steam generator has 12,580 thermally treated Alloy 690 tubes that have an outside diameter of 0.75 inch and a nominal wall thickness of 0.042 inch. The tubes were with a spacing of approximately 0.866 inch.

The tubes were hydraulically expanded at each end for the full depth of the tubesheet. The tubesheet is 25 inches thick (with the clad, the tubesheet is 25.25 inches thick). The Siemens method of tube expansion was used to expand the tube into the tubesheet, which includes a hard roll near the top of the tubesheet and the end of the tube.

The tubes are supported by a flow distribution baffle, horizontal lattice grid supports, batwing (diagonal) supports, and vertical straps. All tube supports are constructed from Type 409 stainless steel. The flow distribution baffle is on the cold-leg side of the steam generator. There is one batwing support on each side of the steam generator and 5 vertical straps. The batwing supports all tubes, whereas the vertical straps only support specific tubes (except for VS3 which is the central support and supports all tubes). Figure 2-40 illustrates the tube support configuration and numbering. The U-bend region of the tubes in rows 1 through 17 received a supplemental thermal treatment (stress relieving) after bending.

The replacement steam generators have "U"-shaped tubes in rows 1 through row 17, and have tubes with two 90-degree bends (referred to as square bends) in all rows greater than row 17.The bend radius is 3 inches for row 1 and 11 inches for row 17. The square bends have a 10-inch bend radius. The tube supports have three basic configurations -(1) horizontal grids (eggcrates/lattice) that provide support to the vertical run of the tubes, (2) vertical grids that provide vertical and horizontal support to the horizontal run of the tubes in the upper bend region, and (3) diagonal strips (batwings) that provide out-of-plane support to the 90-degree bends.

The upper tube bundle support system (1) supports the horizontal tube spans against high velocity, two-phase cross flow, (2) permits an expanded vertical tube pitch (from 1.0 inch to1.75 inches) so as to promote free flow through the bend region and prevent low-flow dryout regions, and (3) supports the upper tube bundle via structural beams against postulated accident condition loads, seismic loads, transportation loads, and dead weight. The U-bend support structure for the replacement steam generator differs from the original design in that it includes welded connections between the vertical grids and the diagonal (batwing) supports. Other features of the U-bend support system are that the batwings bisect the 90-degree bends, the bend region supports are perforated and narrower than the original design, and the bend region supports have ventilation holes. These changes in design improve the thermal/hydraulic conditions in the upper bundle region, preventing crevice dryout and reducing secondary-side fouling, as well as addressing tube-wear phenomena observed in the original steam generator. The diagonal strips (batwings) are located at every row and are designed to prevent out-of plane deflection and thus preclude the deflection amplitude required for fatigue.

It is now beyond time for CA Gov. Brown to make sure that the CPUC demands that SCE & SDG&E issue refunds for the 54 MILLION DOLLARS A MONTH rate payers have and continue to pay for SORE (San Onofre Reactor Emergency)...

http://is.gd/m185qq

SCE & SDG&E shareholders should N☢T profit on the backs of Rate payers!

It is not just these Utilities, what would all the State and Local Leaders do without all the money that these same utilities are giving them; is if right to ask Leaders to shoulder some of the losses caused by a Utility Debacle or should they be exempt like national US Leaders from all hardships because they are treated special by the Nuclear Industry?

I asked someone knowledgable (Nuclear Deep Throat) and here is what I learned:

Based on my conversation with SONGS Manager, SCE has already charged Partially (75 %) Ratepayers for Decommisioning and Dismantling Units 2 & 3.

According to NRC, Licensees may choose from three alternative decommissioning strategies: DECON, SAFSTOR, or ENTOMB.

Under DECON (immediate dismantlement), soon after the nuclear facility closes, equipment, structures, and portions of the facility containing radioactive contaminants are removed or decontaminated to a level that permits release of the property and termination of the NRC license.

Under SAFSTOR, often considered “delayed DECON,” a nuclear facility is maintained and monitored in a condition that allows the radioactivity to decay; afterwards, it is dismantled and the property decontaminated.

Under ENTOMB, radioactive contaminants are permanently encased on site in structurally sound material such as concrete and appropriately maintained and monitored until the radioactivity decays to a level permitting restricted release of the property. To date, no NRC-licensed facilities have requested this option.

Costs and Finance

Prepayment, where money is deposited into a separate account to cover decommissioning costs even before the plant begins operation. This may be done in a number of ways but the funds cannot be withdrawn other than for decommissioning purposes.

External sinking fund (Nuclear Power Levy): This is built up over the years from a percentage of the electricity rates charged to consumers. Proceeds are placed in a trust fund outside the utility's control. This is the main US system, where sufficient funds are set aside during the reactor's operating lifetime to cover the cost of decommissioning.

Surety fund, letter of credit, or insurance purchased by the utility to guarantee that decommissioning costs will be covered even if the utility defaults.

In the US, utilities are collecting 0.1 to 0.2 cents/kWh to fund decommissioning. Utilities must then report regularly to the NRC on the status of their decommissioning funds. Ratepayers have been paying into a decommissioning fund since the 1980s. The fund is only examined publicly every three years. The most recent report in 2011 estimated it would take about $3.7 billion to decommission all three units at San Onofre.

Edison and SDG & E combined had collected about $3.5 billion, though some of that may be needed to complete the decommissioning of Unit 1. There are also questions around how market forces have affected the value of the fund. Fund managers are petitioning currently to change the way they invest the money.

Much more quality tech talk about SORE (San Onofre Reactor Emergency) in the comments here: http://is.gd/ocyCoA