Leaks and Cracks in the Machine
By PAUL KOBERSTEIN
A nuclear power plant is one of the most dangerous machines ever devised. A nuclear plant with defects can be even more dangerous. Two major original components of the Columbia Generating Station came with serious defects, including the reactor containment system, as revealed in Part 1 of this series, and the condenser.
The condenser’s role is to help move water and steam, the lifeblood of a nuclear power plant, through a system of pipes, tubes and turbines. Brass metal tubes inside the condenser started leaking soon after the plant opened in 1984. The brass material is cheaper, softer and less durable than alternatives that could have been installed instead, such as stainless steel and titanium.
Meanwhile, the condenser’s steel outer shell, which encases the tubes, recently started to crack, a possible indication that the plant or its components are becoming brittle with age or aren’t sturdy enough to handle prolonged exposure to superhot temperatures and extreme air pressures.
The leaky tubes were recently replaced. The plant’s original condenser shell was repaired, and is still in service.
The cracks in the condenser were never publicly disclosed by Energy Northwest the plant’s owner. The cracks were revealed in invoices submitted by contractor Babcock & Wilcox, which welded them shut in 2011. The invoices were obtained by Cascadia Times in a public records request.
The 1,300-ton condenser — which is located in the basement of the secondary containment building, one floor beneath the reactor and several stories below the spent fuel pool — plays a key role in the process of generating electricity at the plant. This process starts when the nuclear reactor boils highly purified water into steam. A series of pumps deliver the steam to the turbines where it makes electricity. After leaving the turbines, the steam moves on to the condenser, which reduces it back to water. Pumps return the water to the reactor where it is boiled into steam once again. The process repeats itself in a continuing loop.
Inside the condenser, the steam is cooled by a separate loop of fresh water drawn from the Columbia River. This secondary loop of water flows through the condenser’s 50-foot-long tubes at the rate of 550,000 gallons per minute. These tubes serve as heat exchangers: the river water inside the tubes is heated by the steam as the steam cools and condenses back to a liquid. Meanwhile, the water in the secondary loop is sent over to six giant cooling towers where it is re-chilled in preparation for another round trip to the condenser.
Radioactive waste gases and particles emitted by the reactor also collect in the condenser. This waste is released from the condenser through a vent, routed through high efficiency particulate air (HEPA) filters and then released to the outside environment. Energy Northwest says the gases emitted by the condenser are the major source of gaseous radioactive waste at the plant and are released continuously. After 1999, the volume and radioactivity potency of this waste increased exponentially, as we will see in Part 7.
Cascadia Times gathered details about the plant’s problematic condenser from documents obtained from Energy Northwest under the federal Freedom of Information Act and the state of Washington’s Public Records Act. These documents included:
a 2006 report, “Main Condenser Upgrade Scoping Study,” by Energy Northwest consultant Sargent & Lundy;
invoices from contractor Babcock & Wilcox that provide details of repair work performed on the condenser in 2011, along with photographs of three cracks in the condenser shell;
inspection reports on the condenser that go back to 2000;
a 2011 lawsuit filed by Babcock & Wilcox against Energy Northwest seeking damages of $50 million, alleging that the plant was in an a poorly maintained condition and posed unexpectedly high radioactive contamination risks to workers on the condenser repair project; and
a report entitled “Main Condenser White Paper,” by W. Scott Oxenford, the plant’s chief nuclear officer, published in 2006. Oxenford’s paper is noteworthy because of its frank detailed assessment of Columbia’s condenser problems. Oxenford may have been able to be candid in his report because he was actually an executive on loan to Energy Northwest from an industry group, the Institute for Nuclear Plant Operations (INPO). He no longer works at the Columbia plant.
Workers for Babcock & Wilcox discovered and sealed this four-inch crack and two other cracks shown in the photographs below at the Columbia Generating Station in 2011.
It’s not completely clear how many cracks developed in the condenser. Energy Northwest said there was only one crack, but a Babcock & Wilcox invoice provided photographs of three different cracks. Energy Northwest’s inspection reports suggest the crack or cracks occurred in 2011, possibly when workers removed the much heavier old condenser to make way for the much lighter new model.
A Babcock & Wilcox invoice dated Sept. 6, 2011, stated:
“During a routine B&W inspection, cracks were found in 19 line zone wall above 5” pressure tie pipe, from the 4th pipe from the north condenser shell wall (471’ elevation). The cracks are through the condenser wall and will require B&W to find the length and the extent of the damage. B&W will then repair this damage to ENW’s condenser shell.”
The cracks in the condenser were not revealed or discussed during Columbia’s relicensing process from 2010 to 2012, an omission that deprived the public of an opportunity to learn about the cracks or discuss them with the company or federal regulators. Victor Dricks, a spokesman for the US Nuclear Regulatory Commission, said the topic didn’t come up because the agency didn’t believe the cracks were a safety issue. Energy Northwest Spokeswoman Angela Smith said the company never saw a need to reveal the existence of the crack to the public because “the crack was fixed.”
But the NRC’s rules that govern the relicensing process say that the structural integrity of the condenser shell is supposed to be analyzed during an “Aging Management Review.” If such an analysis was ever done, it was never mentioned in any relicensing documents or released to the public
Dricks said the cracks in the condenser posed no risk to the public, such as by creating a new pathway for radioactive particles to escape to the outside environment. The condenser is kept at a vacuum, which prevents radioactive particles and gases from exiting the plant except via the normal route: up the Reactor Building stack.
The condenser appears to have had problems that were more serious than just cracking.
The condenser contains about 48,000 tubes, 2,000 of which – roughly 4 percent — sprang leaks and were plugged during the first 27 years of plant operations. In 2011, Babcock & Wilcox replaced the old brass tubes with new tubes made of a much stronger and much more expensive alloy, titanium.
Tubes leaks are an industry-wide problem, and are usually addressed by replacing, rather than plugging, the tubes. Between 1976 and 1994, about 14 of the 35 GE-designed boiling water reactors in operation in the United States replaced all or part of their condensers because of tube leaks. The Columbia plant was only one of a few plants with a tube-leak problem that did not replace its tubes. The others included Vermont Yankee and River Bend in Louisiana. Instead, Columbia chose to plug its leaks, a less expensive option than tube replacement in the short term but a costly one in the long run.
The problem arose when the condenser’s brass tubes slowly crumbled on the inside due to chemistry problems that appeared soon after the plant first opened. As the tubes sprang leaks, copper leached out of the brass alloy and joined the river of water headed for the reactor. About 75 percent of the leaks occurred during the plant’s first few years. After chemistry adjustments were made, the rate at which new leaks developed slowed down.
Copper became a serious safety issue at the plant because it would travel with the reactor cooling water and enter the reactor vessel. Once inside the reactor it had the potential to damage the fuel. Columbia Generating Station became known among nuclear industry insiders as a “high copper plant” because of the high copper content of its reactor cooling water.
When it reached the reactor, the copper would form a corrosive layer of crud on the surfaces of the fuel cladding, the outer layer of fuel rods, or on any surface it could find. (The official industry term for this material is actually “crud.”) Such corrosion has caused long axial splits of the clad, allowing fission products, such as Cobalt 60, to spread to other parts of some plants and to the outside environment. Corrosion caused by the crud can also damage the fuel itself, which has occurred at other boiling water reactors.
Copper corrosion at Columbia has rendered large quantities of fuel unusable, costing Energy Northwest tens of millions of dollars in reduced power.
The cladding prevents radioactive fragments from escaping the fuel and entering the stream of coolant water and contaminating it. Several dangerous radioactive isotopes that could only have come from the reactor have been detected in Columbia’s airborne effluent, including strontium 89 and 90, cobalt 58 and 60, technetium, iron, cesium, silver, sodium, manganese, zinc, arsenic, molybdenum, chromium, zinc, bromide and copper.
In addition to leaching copper, the brass tubes at Columbia developed a large number of tiny holes that became a gateway through which radiological contamination could escape. Much of this contamination exited the plant via the reactor building stack, reaching the outside environment and potentially members of the public.
Most plants with brass tubes used a special filtration system called “deep bed demineralizers” to remove the copper and other contaminants in order to prevent them from reaching and damaging the fuel. Columbia and Vermont Yankee were the only two plants in the US with brass tubes that operated without the expensive deep bed filtration systems.
After the mid-1990s, Energy Northwest considered several proposals from its engineering staff to replace the condenser tubes, but on each occasion, the utility rejected those plans because of cost.
“Condenser material replacement is clearly the preferred solution to eliminate leaks and copper sources, ensuring long-term reliability of Columbia’s fuel, reactor vessel and internals,” argued Oxenford, the plant’s chief nuclear officer, in his white paper. “Columbia’s management has thoroughly reviewed options for managing ongoing condenser challenges. On each occasion, continued operating risks were accepted instead of taking action, primarily to avoid costs and extended outage length.”
The cost of replacing the tubes may have been considered to be high, but the ongoing financial burden of operating a plant with leaky tubes was also high, according to the 2006 study by the Chicago engineering consulting firm Sargent & Lundy. In 2005 alone, the Energy Northwest spent $5.4 million on tube leak detection and plugging, including labor costs and the value of lost power production. At that rate, it would take only eight years for the cost of tube plugging to exceed the estimated cost of tube replacement, which in 2008 was estimated at $40 million, including $7 million for parts and $33 million for labor.
But Energy Northwest preferred a penny-wise and pound-foolish approach that had been advocated by the Bonneville Power Administration, a federal agency that was its sole electricity customer. The BPA has a contractual right to reject Energy Northwest budgets. Energy Northwest documents show that the BPA had been behind decisions to plug the tubes, rather than replace them.
For example, Oxenford told the Energy Northwest board in October 2009: “Back in the 1990s, there were a lot of decisions made about cancelling or deferring projects and programs due to a request from BPA to cut costs,” according to the meeting’s minutes. “Columbia is faced today with the repercussions of the decisions to under-invest in the station made back then and has been playing catch-up the last few years.”
Sid W. Morrison, chairman of the Energy Northwest board of directors, repeatedly expressed his frustration with what he perceived as the BPA’s emphasis on costs over safety. He also criticized his own board for showing a lack of “backbone” in dealing with the BPA.
For example, at an April 23, 2008, meeting of the Energy Northwest Executive Board, Morrison noted that “in the past Energy Northwest deferred equipment upgrades in order to lower budgets numbers at BPA’s request,” according to the minutes. He also said he was encouraged when Energy Northwest demonstrated “the backbone to stand up and demand the replacement of the condenser and added that CGS needs to catch up with the industry in equipment upgrades/repairs/replacements.”
He also noted that Energy Northwest management and its Executive Board have “the responsibility to ensure the safe reliable operation of the plant.”
While the BPA tried to reduce costs, it was also highly critical of the plant’s poor performance, which it deemed “one of the worst performing nuclear reactors in the country, Morrison told the Washington state Energy Facility Site Evaluation Council in April 2010.
On at least one occasion, the BPA publicly threatened to pull the plug on the Columbia plant if it didn’t trim costs, according to the utility’s self-published history written in 2000 by Gary Miller. In 1992, BPA Assistant Administrator Sue Hickey, angry at the plant’s inefficient operating performance and the high cost of its power, went public with her apparently long-simmering concern that the plant must become competitive soon or close. “We’ve got to see an improving trend and we’ve got to see it soon,” she insisted.
In April 2011, when Babcock & Wilcox Nuclear Engineering began the tube replacement project, the job was budgeted to be finished in 53 days, but ended up taking 178 days. The delay caused the project to overrun Energy Northwest’s budget by $19 million. The delay also caused a great deal of angst among Energy Northwest executives, who were had reason to worry about what the Bonneville Power Administration might do in response.
Leaks in the condenser, Oxenford wrote in his white paper, led to unplanned refuelling outages, increased employee exposure to radiation, and increased radioactive releases to the environment. Airborne radioactive emissions from the condenser grew by a factor of 123 from 1999-2010, and radioactive dosages received by a hypothetical person living next to the plant site boundary that resulted from the condenser’s emissions grew by a factor of 264 during those same years.
After Energy Northwest replaced the tubes in 2011, the emissions of radioactivity from the reactor retreated by about 60 percent. But in 2012 these emissions still measured 45 times larger than 1999 levels.
Energy Northwest’s approach to the leaky tube problem also led to the creation of dangerous working conditions near the condenser and throughout the plant.
After 2000, plant workers received a steadily increasing amount of exposure to radiation, as the chart below illustrates. “Columbia’s radiation exposure performance is in the worst quartile in the industry,” Oxenford wrote in his 2006 white paper. “Columbia is currently the worst plant based on source term measurements.” From 2009 to 2011, workers at only one other nuclear power plant in the United States received a higher dosage than Columbia, according to the NRC, the Davis-Besse plant in Ohio, as show in Part 9 of this report.
Figure 1. This graph shows a rolling three-year average of total workforce dosages at the Columbia Generating Station during years of refuelling outages from 2001-2011. Workers are exposed to much higher amounts of radiation during refuelling outages when the reactor is not operating.
When Babcock & Wilcox workers entered the plant to replace the tubes, they encountered radiation dangers that were greater than they had been led to believe by Energy Northwest, according to the B & W lawsuit. “The extent of radiological contamination in the work environment was far more extensive than had been disclosed by ENW (Energy Northwest) or that should have been reasonably expected based on industry norms for a boiling water reactor condenser,” it said.
“While ENW represented that the work environment was a very low dose radiological area with limited radiological contamination, actual conditions encountered necessitated work in an environment with a much higher level of nuclear contamination than was disclosed or which could have been reasonably expected,” the lawsuit claimed.
The ventilation system in the work area was in need of “constant repairs, corrective action, stop-work orders, unexpected emergency plans to deal with airborne contamination, and new requirements for respiratory protection,” the lawsuit stated. “As a result of the excessive contamination and deficient ventilation system, workers were required to wear extensive protective gear, including double protective suits, full face masks and respirators, which greatly diminished worker productivity.”
Moreover, Babcock & Wilcox said Energy Northwest provided the contractor with “incomplete and inadequate design documents.” B & W said that Energy Northwest had the “contractual responsibility to provide completed design documents and to extend the time for contract performance and to increase the contract value once final design documents were provided.”
As B & W discovered, certain items were “not fully disclosed,” other plant conditions were “omitted or misrepresented,” and plant conditions were “inadequately and/or improperly described.”
At one point, actions by Energy Northwest allowed hydrogen to remain in pipes that were supposed to be purged of their contents, leading to a small hydrogen explosion, the Babcock & Wilcox lawsuit said. Fortunately, no one was hurt.
Although industry experience shows that the new titanium tubing installed by Babcock & Wilcox has been effective at curtailing leaks everywhere it’s been used, Columbia Generating Station still experienced problems. In September 2011, during testing of the new condenser tubes, workers detected four pinhole leaks in the new tubing, according to the minutes of an Energy Northwest Executive Board meeting on September 21, 2011. After the leaks were repaired, re-testing indicated one of the leaks had to be fixed again.
On September 6, B & W sent an invoice to Energy Northwest seeking about $2.7 million in its final billing for the work. But Energy Northwest refused to make the payment, and informed Babcock Wilcox that it owed Energy Northwest almost $2.8 million instead for various costs and expenses.
On Oct. 21, 2011, Babcock & Wilcox sued Energy Northwest, seeking damages of $50 million; Energy Northwest settled the case seven months later for $19 million. The case never went to trial; the parties settled the case through mediation the following May.
Energy Northwest and Babcock & Wilcox each denied each other’s allegations in the case. In the end, after 15 contract modifications, Energy Northwest’s original $32.8 million contract with Babcock & Wilcox cost a total of $52.5 million, plus Washington sales tax.
Although the contract required each party to clear public statements with each other, Brent Ridge, Energy Northwest’s chief financial officer, chided Babcock & Wilcox in the press for a series of alleged blunders that he contended also contributed to the extended repair outage.
Ridge said that a “lessons learned analysis” conducted by Energy Northwest found that Babcock & Wilcox “was not sufficiently prepared to conduct the work and there were signs of that prior to the outage,” according to the Tri-Cities Herald.
“B&W initially acted like it was working on a project such as a coal plant rather than a nuclear plant,” the newspaper quoted Ridge as saying.
Babcock & Wilcox officials declined to respond to questions about the case or their work for Energy Northwest. A company spokesman issued a single statement that said, “We believe B&W’s performance on this project – which resulted in the longest period of operation at the highest power output in the plant’s history, with no claims filed after our work was complete – demonstrates the quality of our work product. Questions pertaining to the condition of the plant and other areas outside of B&W’s scope of work should be referred to the plant owner.”
This drama unfolded under the watchful eyes of NRC inspectors who are at the plant every day. The NRC cited the plant for excessive worker contamination and made other critical comments. The NRC found that “poor job execution” and “inadequate planning” on the part of Energy Northwest were to blame for the excessive dosages to workers. The NRC also noted that Energy Northwest had not assigned a project manager to the job.
Although the old, leaky condenser is gone, Bonneville Power Administration will continue to exercise budgetary control over Energy Northwest maintenance decisions.
Should there ever be an accident at the Columbia Generating Station, there will be an investigation. Surely someone will ask about the role played by the Bonneville Power Administration, especially its efforts to defer maintenance at the plant to reduce its costs.