Failed reactor control rods in the USA GE Mk1 reactors.

http://www.google.com.au/url?sa=t&rct=j&q=browns+ferry+conrol+rod+cracks&source=web&cd=1&ved=0CCcQFjAA&url=http%3A%2F%2Fpbadupws.nrc.gov%2Fdocs%2FML1122%2FML112230478.pdf&ei=0S5EUOfsNMmsiAef6oCwCw&usg=AFQjCNENW_p4dNN7AmT5W4TqOhKZJzQaiA

“DUANE ARNOLD ENERGY CENTER

Cracks have been detected in the collet housings of the control rod
drives at Dresden Unit 3, Browns Ferry 1,-and Vermont Yankee. The
problem appears to be a stress assisted corrosion problem that may
be generic to most boiling water reactors. In light of this experience,
we believe that appropriate changes to technical specifications for
this type reactor are needed that will prohibit extended operation witb
immovable rods. Accordingly., unless you inform us in writing within
20 days of the date of this letter that you do not agree with this
course of action, including your reasons, we plan to initiate steps
to issue the enclosed change to the technical specifications of your
facility. A copy of our related safety evaluation on this matter
is enclosed.
Sincerely,
George Lear, Chief
Operating Reactors Branch #3
Division of Reactor Licensing” Sept 23 1975

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Blue Ridge Environmental Defense League http://www.BREDL.org PO Box 88 Glendale Springs, North Carolina 28629 BREDL@skybest.com (336) 982-2691 NRc submission Oct 27 2011
to Plant Licensing Branch 11-2
Division of Operating Reactor Licensing
U.S. Nuclear Regulatory Commission
11555 Rockville Pike
Rockville, MD 20852

“Control Rod Cracks

Plant inspections done by the manufacturer indicate that the Browns Ferry Nuclear
Plant suffers from cracking of the control rods necessary for shutting down the reactor.
Based on this information, the manufacturer predicts that the control rods will fail sooner.
An NRC Information Notice (IN) issued in June 2011 states:
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice (IN) to inform addressees that GE Hitachi Nuclear Energy (GEH) has
discovered severe cracking in Marathon control rod blades (CRBs) near the end
of their nuclear lifetime limits in an international BWR/6. As a result of
investigations into the cracking, GEH has determined that the design life of
certain Marathon CRBs may be less than previously stated and is revising the
end-of-life depletion limits of these CRBs. The NRC expects that recipients will
review the information for applicability to their facilities and consider actions, as
appropriate, to avoid similar problems.4

Not only did 100% of the control rods inspected suffer from cracking, the damage
was more widespread and more serious than previously known. The Information Notice
continued:
In August 2010, GEH, as part of its surveillance program to monitor Marathon
CRB performance, visually inspected four discharged CRBs at an international
BWR/6 and found cracks on all four CRBs. The cracks were much more
numerous and had more material distortion than those observed in previous
inspections of Marathon CRBs. The cracks were also more severe in that they
resulted in missing boron-carbide capsule tube fragments from two of the
inspected CRBs.5

The list of suspect plants includes Browns Ferry 1, 2 and 3 and sixteen more GE
Mark I BWRs: Cooper, Dresden 2 and 3, Duane Arnold, Fitzpatrick, Hatch 1 and 2,
Monticello, Nine Mile Point 1, Oyster Creek, Peach Bottom 2 and 3, Pilgrim, Quad Cities
1 and 2, and Vermont Yankee.6 Based on this evidence, 83% of the GE Mark I reactors
in the United States are likely operating with cracked control rod blades.
Analysis of the missing fragments found in two of the four control rods inspected
uncovered no negative effects on plant performance; however, to make this finding at
Browns Ferry or the other affected plants would require individual reactor testing.
Browns Ferry was TVA’s first nuclear power plant. The initial design life-span of
nuclear plants is 30 to 40 years. All three Browns Ferry units are approaching the forty-
year mark: Unit 1 began commercial operation on August 1, 1974, Unit 2 on March 1,
1975 and Unit 3 on March 1, 1977. NRC renewed the operating licenses for all three
Browns Ferry reactors in May 2006, allowing TVA to continue operating them until
2033, 2034, and 2036, respectively. The new information regarding control rod cracks
came after the renewal.
Control rod mismanagement was involved in at least two major nuclear accidents, at
the Argonne Low Power Reactor and Chernobyl. The history of Chernobyl is familiar;
less well known are events at Argonne, where the improper withdrawal of the control rod
mechanism at the Army’s experimental reactor in Idaho caused an explosion which killed
three operators and released 1100 curies of fission products into the atmosphere. 7 In
four milliseconds this small reactor went from 200 kilowatts power to 20 million
kilowatts.8 Although the NRC Information Notice includes no specific enforcement, it
does point to the NRC’s expectation that plant operators will act to avoid control rod
problems caused by these flaws. NRC should issue an order to TVA to check these
components and not merely rely on the IN suggestion.

Notes: 4 NRC Information Notice 2011-13: Control Rod Blade Cracking Resulting in Reduced Design Lifetime,
June 29, 2011, ADAMS Accession No. ML111380019
5 Id.
6 The other four listed in the IN are Clinton, Grand Gulf, Perry and River Bend.

7
Horan, J. R., and J. B. Braun, 1993, Occupational Radiation Exposure History of Idaho Field Office
Operations at the INEL, EGG-CS-11143, EG&G Idaho, Inc., October, Idaho Falls, Idaho (retrieved 10/6/11
from Wikipedia).
8
Steve Wander (editor) (February 2007) “Supercritical” System Failure Case Studies (NASA) 1 (4).
http://pbma.nasa.gov/docs/public/pbma/general/sl1_sfcs.pdf (retrieved 10/6/11 from Wikipedia)

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Channel 9 KTRE

Manufacturer reports potential safety issue at Browns Ferry

Posted: Feb 18, 2011 8:10 AM EST
Updated: Mar 18, 2011 10:14 AM EST
Limestone County, Alabama –
By Trang Do

LIMESTONE COUNTY, AL (WAFF) – Workers at TVA’s Browns Ferry nuclear plant are closely monitoring the water coming in and out of the plant, after a parts manufacturer recently notified TVA of a possible issue with some important pieces to its reactors.

Brown Ferry is one of more than two dozen nuclear plants nationwide that use GE Hitachi control rods or blades in its boiling water nuclear reactors.

Control rods in a nuclear reactor are like the brakes on a car. When you want to slow down your car, you hit the brakes. When you want to reduce the amount of energy produced at a nuclear reactor, you insert more control rods.

Depending on where the rod is placed in a reactor, it could last as long as three decades.

However, GE Hitachi recently informed the Nuclear Regulatory Commission in a report that the rods need to be replaced more frequently than the company initially thought.

GE Hitachi discovered extensive cracking in some rods at a nuclear plant overseas — a defect which could create a safety hazard.

Out of 555 control rods in Brown’s Ferry’s three reactors, 56 of them are the GE Hitachi brand.

TVA spokesman Ray Golden says plant officials are well aware of the issue. One way to tell if the rods begin cracking is if higher levels of certain chemicals begin appearing in the plant’s runoff water. Golden says this has not yet been a problem at Browns Ferry.

“We are continuously monitoring the water that goes in and out of the reactor all the time,” Golden said. “We know that if these blades started to crack, we would see elevated levels of boron and elevated levels of tritium.”

NRC spokesman Roger Hannah says it’s not an immediate safety concern, but something that does need to be closely watched.

Golden says TVA officials are considering switching to a different brand of control rods once the current ones are ready to be replaced.

©2011 WAFF. All rights reserved.

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NRC Meeting On GE BWR Reactors – Live Blog Transcript

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February 17, 2011
Potential fuel rod hazard present at Browns Ferry plant
Associated Press

— MONTPELIER, Vt. (AP) — Control rods at units 1, 2 and 3 of the Browns Ferry Nuclear Plant are among those at two dozen reactors around the country that a major manufacturer in the nuclear industry is reporting as having the potential for being a “substantial safety hazard.” The report centers on control rods at Vermont Yankee and was made public Wednesday by the federal Nuclear Regulatory Commission.

GE Hitachi Nuclear Energy said it had discovered extensive cracking and “material distortion,” at the Vermont location and likely would recommend that the boiling water reactors using its Marathon control rod blades replace them more frequently than they had been told to previously.

“The design life if not revised, could result in significant control blade cracking and could, if not corrected, create a substantial safety hazard and is considered a reportable condition,” the company said in its report to the NRC.

Both David Lochbaum of the Union of Concerned Scientists and Arnold Gundersen, a former nuclear industry engineer who now frequently consults with groups critical of the industry, said the faulty blades could make affected control rods inoperable.

“It could either slow down or stop the control rod from inserting” when plant operators were trying to reduce power or shut a plant down, Lochbaum said.

Gundersen said control rods “are like the brakes on a nuclear reactor. It’s almost like they have a 100,000 mile warranty on them and they need to be changed out at 40,000.”

He added that the reactors also have an emergency brake: an “explosive valve” to be used in emergencies when operators are unable to gain control of the reaction by inserting control rods. The valve forces water containing high levels of boron, which slows and eventually stops the reaction by absorbing neutrons.

After using that measure, Gundersen said, “it takes months to clean up” while the plant is shut down. In their training reactor operators are “taught it’s there, but you pray you never have to use it.”

Signs of cracking in the blades would include increased levels of boron and tritium, a radioactive isotope of hydrogen, in the water used to cool the reactor, said Neil Sheehan, an NRC spokesman.

“As long as there is no significant increase in boron or tritium observed, the recommendation would be continue operation until the end of the operating cycle,” Sheehan said in an e-mail.

Jim Klapproth, chief engineer with GE Hitachi Nuclear, said in a statement, “Customers with affected control blades can avoid the safety concern by monitoring the water chemistry of their plants and replacing affected blades prior to the end of the revised service life.”

Commercial reactors in the U.S. are divided into two classes: boiling water reactors, the type of concern here, and pressurized water reactors. GE Hitachi listed the other affected plants as follows:

Nine Mile Point, Unit 1 and Fitzpatrick plants near Oswego, N.Y.; Millstone, Unit 1, Waterford, Conn.; Pilgrim, Plymouth, Mass.; Vermont Yankee, Vernon, Vt.; Grand Gulf, Port Gibson, Miss.; River Bend, St. Francisville, La.; Clinton, near Clinton, Ill., Oyster Creek, Lacey Township, N.J.; Dresden, Unit 2; Dresden, Unit 3, near Morris, Ill.; Peach Bottom, Unit 2; Peach Bottom, Unit 3, Peach Bottom Township, Penn.; Quad Cities, Unit 1; Quad Cities, Unit 2, near Cordova, Ill.; Perry, Unit 1, North Perry, Ohio; Duane Arnold, near Palo, Iowa; Cooper; near Brownville, Neb.; Monticello, Monticello, Minn.; Brunswick, Unit 1; Brunswick, Unit 2, near Southport, N.C.; Hatch, Unit 1; Hatch, Unit 2.

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The following was received by NRC from GE HITACHI Nuclear Energy of Wilmington, NC via facsimile:

“A recent inspection of near ‘End-of-Life’ Marathon Control Rod Blades (CRB) at an international BWR/6 has revealed crack indications. The CRB assemblies in question were manufactured in 1997. GE Hitachi Nuclear Energy (GEH) continues to investigate the cause(s) of the crack indications. Once the cause of the crack indications is determined, GEH will evaluate the nuclear and mechanical lifetime limits of the Marathon Control Rod Blade design in light of the new inspection data, and make revised lifetime recommendations, if necessary.

“This 60-day interim notification, in accordance with 10CFR Part 21.21(a)(2), is sent for all plants that are D lattice, BWR/2-4 or S lattice, BWR/6 plants. Since there have been no reported cracking occurrences in C lattice assemblies to date, these CRBs are tentatively eliminated from the investigation. C lattice, BWR/4-5 plants have been included on Attachment 2 for identification. Should the results of the investigation implicate the C lattice plants, the final resolution to this 10CFR Part 21 evaluation will include the C lattice plants.”

The D lattice and S lattice plants in the US that are affected by this notification include Nine Mile Point, Unit 1; Millstone, Unit 1; Fitzpatrick; Pilgrim; Vermont Yankee; Grand Gulf; River Bend; Clinton; Oyster Creek; Dresden, Unit 2; Dresden, Unit 3; Peach Bottom, Unit 2; Peach Bottom, Unit 3; Quad Cities, Unit 1; Quad Cities, Unit 2; Perry, Unit 1; Duane Arnold; Cooper; Monticello; Brunswick, Unit 1; Brunswick, Unit 2; Hatch, Unit 1; Hatch, Unit 2; Browns Ferry, Unit 1; Browns Ferry, Unit 2; and Browns Ferry, Unit 3.

References:

NRC Event Report 46348: http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2010/20101021en.html#en46348
No US reactors to shut over GE/Hitachi crack report:
http://www.reuters.com/article/idAFN219367520101021?rpc=44

GE HitachiNuclear Energy Mrathon™ Control Rods Fact Sheet:
http://www.gepower.com/prod_serv/products/nuclear_energy/en/downloads/marathon_control_rods_factsheet.pdf

GE HitachiNuclear Energy Marathon-5S™ Control Rod Blade Product Update:
http://www.gepower.com/prod_serv/products/nuclear_energy/en/downloads/marathon_5s.pdf

One Response to “Failed reactor control rods in the USA GE Mk1 reactors.”

  1. CaptD Says:

    Liked!
    There is lots of “make due” engineering being done that could easily become THE straw that caused a meltdown or worse in these reactors!

    This is yet another reason why the NRC giving out 25 year extensions is unacceptable, except to the Nuclear Industry who hopes to profit from their operation…

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