Although federal officials have said that the problem does not affect key safety systems and is not publicly reportable, they also said it could lead to pump failures and breaks that would contaminate the reactor containment building.June 22:
Nuke plant pump repairs sap PSEG earnings
PSEG’s Salem Unit 2 continued to sit out an ordinarily lucrative run of hot weather last week as the company worked to recover from dozens of critical bolt failures in four key reactor coolant pumps.
Although PSEG has declined to discuss the problem, federal regulators said bolts holding water-moving impellers were found to have broken or sheared off in all four of the 30-foot high pumps in Unit 2. The pumps return cooling water to the reactor core after the coolant passes through heat transfer units that make steam for turbine generators.
Company officials broadly confirmed a problem in mid-May when they reported a delay in restarting the plant from a refueling that began in mid-April.
According to the Nuclear Regulatory Commission, some of the broken bolts wound up in the bottom of the reactor core itself or in plant piping. Part of one damaged pump just above the impeller was believed to have dropped and slightly touched the spinning impeller which can rotate thousands of times a minute.
“As we get into a period of higher demand, the potential financial impact increases,” said Paul Patterson, a financial analyst who follows the industry for New York-based Glenrock Associates. “The sooner they get it back, the better.”
NRC officials said PSEG had to remove all four pumps and send them off-site for work. Although federal officials have said that the problem does not affect key safety systems and is not publicly reportable, they also said it could lead to pump failures and breaks that would contaminate the reactor containment building.
“At this point, we are not commenting further on the bolting issue until the unit returns” to service, said PSEG Nuclear spokesman Joe Delmar. Interim reports on progress or potential restart schedules, he said, could affect power markets and pricing.
Patterson said that the relatively low costs for nuclear plant fuel and day-to-day operations gives it an advantage during high-demand periods, when prices are high. A quick comeback is uncertain, however.
“It’s not just a simple situation where you fix the problem,” Patterson said. “It’s a highly regulated facility, as are all nuclear plant. The NRC is obviously going to want to see that the situation is fixed, and they also want to see what caused it. That takes some time.”
Unit 2 is one of three reactors at the Salem/Hope Creek nuclear complex in New Jersey, on Artificial Island along the Delaware River southeast of Port Penn.June 10: Salem 2 PCP potential event
(fixed this up a bit on 6/11)You notice the pump seizure with a bolt is an issue with Salem and threatening fuel damage, while a 5 by 12 inch impeller blade, with the lost blade being an inch thick, is not analysed as pump seizure stoppage accident at Palisades. The disparity between these two plant's accident analysis are shocking.Fuel assembly:
So a fourth of the water flow in the core quickly stops...hot spot and areas where there is higher local power levers begin to quickly heat up. May be one fuel pin burst open, may be 10 pins burst open, may be a whole fuel assembly's pins burst open... You could consider any fuel pellet coming in contact with coolant water as super moderated and being able to quickly generate a lot more power and heat than normal at normal power operations. If don’t think it would take a lot of fuel pellets to put out so much power and heat only steam and water vapor would remain in the assembly. So that would cause addition pins to pop. Say the majority of pins popped in a assembly, the pins would be scrambled in the assembly, the fuel pellets would congregate at the bottom of the assembly and clog up the flow. Does those broken fuel pellets at the bottom of the assembly end with in a local "steam explosion", then bend and damage the assembly through the tremendous heat and power being produced there? Is there enough energy in the steam and vapor to seriously damage the neighbor assembly? It is the beginning of a cascaded where pins in another neighbor assembly start to pop and damage the assemble, then another, then another. In this process we might not have scrammed yet.How the assemblies are nestled together:
Thanks NEI. Fuel pins or rods:May be one, two or three assemblies get destroyed, maybe a rod can’t get all the way in the core...but the nuclear reaction stop. diverse cooling to the core is never threatened. What emergency classification would you be in? It would telegraph to outsider how serous the accident is. There is going to be a tremendous amount of freed radioactivity in the core if just one assemble gets destroy...lots if only one or two pins are destroyed. It is going to be a nasty cleanup of the core and it would be questionable if it is worth the price of a cleanup. But there would be little off plant release of radiation.How do you think the outsiders would portray this? The antinukes would say there was a core meltdown. The NRC and plant would say they were always safe. This is just normal and expected. The UFSAR and plant licencing allows this. Can you imagine the media and political debate out of this?
See, basically risk perspective only protects us from a severe core melt...this was mostly a small partial core meltdown with diverse core cooling always available. That is what they mean when they say its safe...safe mean less than severe core meltdown and it wouldn’t happen very often. I saying the political and public fallout would be severe, industry threatening...but it is all really a small partial meltdown. See how the nuclear industry doesn’t protect themselves from such a close near death experience and risk traumatizing a significant segment of our population. One, two, or three destroyed assemblies would be defined a safe and acceptable...but the outsiders would think you are bsing them on a meltdown and loss of another plant.
This just gets worst and worst...I bet the NRC is getting nervous why I called them.
Broken bolts found in all of PSEG Nuclear's Salem 2 reactor cooling pumps
Nonsense ...The NRC says broken off bolts and nuts in all pumps are completely safe and the inspection was completely unnecessary, as the 50 or whatever bolts and nuts rattling around in the coolant and core was always safe. Idiots, what why did you even look...LOWER ALLOWAYS CREEK TWP. — PSEG Nuclear has now found broken-off bolt pieces inside all four of the huge pumps which help cool the nuclear reactor at its Salem 2 plant, officials said.
Errant bolt heads have been found in the bottom of the reactor coolant pumps and even at the bottom of the reactor core itself, settled under the nuclear fuel rods.
Dummies, what did you even count the discovered bolts...the NRC per Palisades precedence says missing and broken parts in the core and coolant are and will be completely safe.And some of the bolt heads that have broken off have not yet been accounted for, federal regulators confirmed Tuesday.
Stress-corrrosion-cracking process is a cover-up...the happy ever after story. Use you dam brain, why didn't they have this problem 20 years ago with the same chemical environment. What didn't they have bolts falling out and cracking 20 years ISCC. It is preposterous they would all crack simultaneously. A few will crack, then sear...then fall out. That is how you would see it.The bolts secure parts known as turning vanes on the inside of the pump. The vanes direct water out of the pump into the reactor where it circulates to cool the core.
Salem 2 has been shut down since April 12 when a rescheduled refueling outage began. During routine inspections, workers found all 20 of the bolts that hold turning vanes in place inside one of the four pumps had failed.
This discovery prompted plant officials to then inspect the three other pumps used to cool the reactor.
In two of the other pumps all of the bolts were found to have failed and broken off. In the fourth pump, nine of the bolts had severed heads, six were intact and the others showed signs of decay, according to Neil Sheehan, spokesman for the Nuclear Regulatory Commission.
"We now have a comprehensive picture what is going on inside of all of the pumps," Sheehan said Tuesday.
Some of the new information came to light in a "Voluntary Notification For An Item of Regulatory Interest" the utility filed with the NRC this week.
In that notice, the utility said in at least one instance the failure of the bolts allowed the turning vane assembly to drop inside the pump. Inspections showed there was "evidence of slight contact" between the turning vane and the impeller — which pulls in and pushes out water — at the bottom of the pump.
But the utility said in the notice there was no danger.
"Salem Unit 2 has had no indications to date of adverse operating conditions of any RCPs (reactor coolant pumps) due to turning vane assembly detachment which would compromise plant safety."
The reactor coolant pumps, which stand about 30 feet tall, were removed from the plant site at Artificial Island, to be taken apart and inspected.
The stainless steel bolts holding the turning vane assemblies in place are about four inches long and an inch wide.
The broken bolts are being blamed on the stress-corrrosion-cracking process, a phenomenon seen in both nuclear power plants and in other industrial plants, Sheehan
I warned the NRC about this, stopping the flow question fuel integrity...said.
The pumps are designed by Westinghouse and there are only 10 of this specific model in question in the world — four at the Salem 2 reactor and six at the Surry Power Station in Surry, Va., which has two nuclear reactors, Sheehan said. While the neighboring Salem 1 reactor is often referred to as Salem 2's twin, Salem 1 pumps have a different bolting configuration.
PSEG Nuclear officials had little further additional comment on the new findings.
"We are proceeding with the removal and repairs as needed for the reactor coolant pumps," said Joe Delmar, a utility spokesman, Tuesday.
Sheehan says agency personnel are closely watching the inspection findings.
"NRC experts are continuing to review this issue, with a focus on PSEG's work to fully understand the extent of the condition and any plans for repairing the pumps prior to the plant being restored to service," Sheehan said.
Sheehan said one of the main concerns was having the loose bolt heads damage or stop the impellers.
Or it will turn into the convenience of the NRC...they don't have enough resources to do two special inspections in region 1 simultaneously.Also, Sheehan said, there could be the possibility of the impeller, moving at such a high rate of speed, striking and disintegrating part of a loose turning vane and sending tiny pieces of metal circulating throughout the reactor cooling system.
Delmar said there is no estimate of when Salem 2 might be ready to go back into service.
Salem 2 is one of three nuclear reactors operated by PSEG Nuclear at its Artificial Island generating site.
The other two — Salem 1 and Hope Creek — remained operating at full power on Tuesday, Delmar said.
I am on the other side of the table than Dave on this. Does't seem much bothers Dave these days? (June 11: Is Dave playing cool because he is in the running for being nomimated for a NRC commisioner position.)PSEG Nuclear workers have found there is a complete failure of all bolts securing water-pushing impellers in three of four Salem Unit 2 reactor coolant pumps, withinvestigations continuing inside the last unit.
The findings, released Monday, emerged after the discovery of broken parts in one of the big, water-moving units forced the company to delay a post-refueling restart last month.
Nuclear Regulatory Commission officials said Monday all retaining bolts were found to be "sheared or failed" in three of four 30-foot-tall reactor coolant pumps in Salem 2 in New Jersey. The pumps force water back into the reactor core after it circulates through systems that make non-radioactive, pressurized steam used to turn generators.
The 1,158-megawatt Unit 2 went offline and began a refueling outage April 13, with the shutdown extended when broken bolt-heads were found on eight of 20 fasteners that secure a bladed "turning vane" part inside one of the pumps. Subsequent examinations found all 20 bolts to be "sheared or failed" in three of the four pumps, which had to be shipped off-site for examination.
"Because the pumps are part of the reactor coolant system, they are part of a barrier against release of radioactive water, though that water would be captured inside the reactor containment building during an accident," said Neil Sheehan, spokesman for the NRC's regional office in King of Prussia, Pennsylvania.
In a limited report on the investigation, PSEG disclosed that investigators found a "detachment and dropping" of a part in a coolant pump, with "slight contact" between the impeller, or blade-like unit that pushes cooling water, and another part that diffuses the pressurized flow.
Joe Delmar, PSEG Nuclear spokesman, said Monday the company is not going to comment any further than what was mentioned in what the company labeled as a "Voluntary Notification for an Item of Regulatory Interest."
"We continue with the repair plan of the reactor coolant pumps," Delmar said in a written statement.
Salem Unit 2 is one of three reactors at PSEG Nuclear's Artificial Island, New Jersey, complex, along the Delaware River southeast of Port Penn and east of Odessa.
Company officials reported that Salem 2 has had "no indications to date of adverse operating conditions" due to detachment of the turning vanes. Salem Unit 1, a near-twin to Unit 2, has the same model pumps with a different bolting scheme.
PSEG and NRC officials have said that stress corrosion – a kind of failure that occurs in some types of metals exposed to particular types of stress, temperature and corrosive conditions – appears to be a likely cause for the bolt failures.
"NRC experts are continuing to review the issue, with a focus on PSEG's work to fully understand the extent of the condition and any plans for repairing the pumps prior to the plant being restored to service," Sheehan said.
Sheehan said later that: "We do not have a hold on at this time that would prevent the unit from being returned to service. However, we would expect that the company would fully understand the issue and effectively repair all of the pumps prior to restart."
David Lochbaum, a nuclear power engineer and specialist for the Union of Concerned Scientists, said Monday that the pumps play a part in plant cooling but are not considered part of the plant's safety system. Loss of bolts could become a safety problem if turbine blades, which spin at thousands of revolutions per minute, or other parts broke loose and penetrated the pump housing or moved into other parts of the cooling system.
Drives me crazy: "said Monday that the pumps play a part in plant cooling but are not considered part of the plant's safety system".
Me"It sounds like they caught it early enough," Lochbaum said, noting that severe problems would likely have created vibrations or wobbling that would have been detected by plant sensors.
Mr Hughey,
To RidsNrrPMSalem.Resource@nrc.gov
Today at 7:36 PM
Mr Hughey,
I talked to your nice senior resident inspector today about the unit 2 PCP troubles.I believe it is the second time since extending the shutdown. I noted to him about Palisades PCP troubles...cavitation, impeller circulation damage, inadequate NPSH and high pump flow outside plant licensing. I forgot to ask these to him. Are Salem's PCP parameters allowed to operate outside their UFSAR (during su). See Palisades most recent IR.
Did any Salem plant PCP impeller blades or anywhere in the pump casing ever have cavitation, pressure pulsing or recirculation (pitting) damage or problems? So that would be impeller blade cracking, lost or detached impeller blades or any kind of cavitation damage. That would be a great question nationwide...certainly the other Salem plant also.
I asked him to pass this up to his management.
1) I request a special inspection on Unit two and one...
2) Immediately on a emergency bases, shutdown plants with identical or similar pumps, inspect all PCP impellers. Generic implication!
sincerely,
Mike Mulligan
Hinsdale, NH
16033368320
Republished from 5/12
Absolute failure of the NRC to make a licensee control quality in a nuclear reactor with Palisades and Salem PCP. So I was bum doped by nuclear employees...it wasn't the diffuser, it was the bolts holding the RCP impeller to the shaft.
Bolt failure found in three SalemUnit 2 reactor coolant pumps
PSEG Nuclear workers have found complete failure of all bolts securing water-pushing impellers in three of four Salem Unit 2 reactor coolant pumps, with investigations continuing inside the last.May 28
The findings emerged after a discovery of broken parts in one of the big water-moving units forced the company to delay a post-refueling restart last month.
Nuclear Regulatory Commission officials said Monday that all retaining bolts were found to be “sheared or failed” in three of four 30-foot-tall reactor coolant pumps in Salem 2. The pumps force water back into the reactor core after it circulates through systems used to transfer heat and create non-radioactive, pressurized steam to turn generators.
The 1,158-megawatt Unit 2 was taken off line for a refueling April 14, with the shutdown extended when broken bolt-heads were found from eight of 20 fasteners that secure a bladed “turning vane” part inside one of the pumps. Subsequent examinations found all of the 20 bolts to be “sheared or failed” in three of the four pumps, which had to be shipped off-site for examination.
“Because the pumps are part of the reactor coolant system, they are part of a barrier against release of radioactive water, though that water would be captured inside the reactor containment building during an accident,” Neil Sheehan, spokesman for the NRC’s regional office in King of Prussia, Pennsylvania, said.
In a limited report on the progress of the investigation, PSEG disclosed that investigators found a “detachment and dropping” of a part in a coolant pump, with “slight contact” between the impeller, or blade-like unit that pushes cooling water, and another part that diffuses the pressurized flow.
Joe Delmar, PSEG Nuclear spokesman, said Monday that the company is “not going to comment any further than what was mentioned in what the company labeled as a “Voluntary Notification for an Item of Regulatory Interest.”
“We continue with the repair plan of the reactor coolant pumps,” Delmar said in a written statement.
Salem Unit 2 is one of three reactors at PSEG Nuclear’s Artificial Island, New Jersey, complex, along the Delaware River southeast of Port Penn and east of Odessa.
Company officials reported that Salem 2 has had “no indications to date of adverse operating conditions” due to detachment of the turning vanes. Salem Unit 1, a near-twin to Unit 2, has the same model pumps with a different bolting scheme.
PSEG and NRC officials have said that stress corrosion, a kind of failure that occurs in some types of metals exposed to particular types of stress, temperature and corrosive conditions – appears to be a likely cause for the bolt failures.
“NRC experts are continuing to review the issue, with a focus on PSEG’s work to fully understand the extent of the condition and any plans for repairing the pumps prior to the plant being restored to service,” Sheehan said.
Sheehan said later that: “We do not have a hold on at this time that would prevent the unit from being returned to service. However, we would expect that the company would fully understand the issue and effectively repair all of the pumps prior to restart.”
May 28 (Reuters) - PPL Corp said Wednesday it completed refueling and maintenance work on its 1,260-megawatt (MW) Unit 1 at the Susquehanna nuclear power plant in Pennsylvania but decided to keep the reactor shut for turbine work.
PPL decided to work on the turbine so the company can complete a root cause analysis of the plant's turbine issues later this year, company spokesman Joe Scopelliti said in an email.
He did not say when the unit would likely return to service.
PPL has worked on or inspected the turbines at both Susquehanna units several times over the past few years. In some cases, the company has shut the unit specifically to look at the turbines, while in other cases PPL used a shutdown for other reasons such as refueling or an unplanned outage to inspect the turbines.
Since 2011, the company has inspected the turbines in Unit 1 at least five times and Unit 2 at least six times. Unit 2 most recently shut for a couple weeks in March for turbine work.
Scopelliti has said in the past the problem is with the low-pressure turbines. He said each unit has three low-pressure turbines and one high-pressure turbine. The low-pressure turbines were replaced in 2003 and 2004.
German engineering company Siemens AG manufactured the low-pressure turbines and is working with PPL to resolve the issue.
The high-pressure turbines, meanwhile, were replaced between 2008 and 2011 as part of an uprate or power increase for the reactors.
Meanwhile, the 1,260-MW Susquehanna 2 was operating at full power early Wednesday, according to a report by the U.S. Nuclear Regulatory Commission.
(It was shortly after the latest turbine trip w/i a day. I don’t know why I can’t come up with the right date. I have talked to numerous inspectors in the last month)
So around my May 8 I called up the Salem senior inspector and left a message. He shortly called me back. We talked about the problems with the recent plant trips. He reminded me he knew me from the Vermont Yankee issues. It was like we was old buddies. He was a NRC facilitator at a few of VY of the contentious meeting. It was few meetings past, when the antis threw cow manure at the inspectors. The NRC had a army of Brattleboro police officers in the meetings and surrounding the high school. There was talk about bringing tanks! I talked to the senior resident about Palisades problems; spoke at length about the meaning of defective PCP impellers. Asked him can you believe the inspectors, said it was safe with the throwing impeller blades all over the place. He didn’t respond. We talked about their brackish service water piping problems...he reminded me they did a rather big piping replacement project.
I just wanted you to know we spent a lot of time talking about Palisades PCP pump problems and I am certain he memorialized the discussion to higher ups.
Poor maintenance and confidence men...
PSEG Nuclear has extended a refueling shutdown of its Salem Unit 2 reactor after discovery of unexplained broken bolt heads in part of the coolant system.Is the Salem nuclear facility in trouble? This is the newest inspection...I'll get the link when it comes up.
Company spokesman Joe Delmar said Wednesday afternoon that "a conservative decision was made to extend the refueling outage to conduct additional internal inspections of the reactor coolant pumps and make any repairs as needed."
Nuclear Regulatory Commission spokesman Neil Sheehan said the bolt tops are likely from a part of the coolant pump system.
"The concern is that if bolts holding the turning vane failed, the vane could drop and impact the rotating pump internals," Sheehan said.
PSEG operates three reactors at its Artificial Island site along the Delaware River in New Jersey southeast of Port Penn. The company's Salem Unit 1 plant has reported three unplanned shutdowns this year, potentially subjecting the operation to increased oversight.
May 9, 2014This report covered a three-month period of inspection by resident inspectors and announced inspections performed by regional inspectors. Inspectors identified five non-cited violations (NCVs) and two findings (FINs) of very low safety significance (Green). The significance of most findings is indicated by their color (i.e., greater than Green, or Green, White, Yellow, Red) and determined using Inspection Manual Chapter (IMC) 0609, “Significance Determination Process (SDP),” dated June 2, 2011. Cross-cutting aspects are determined using IMC 0310, “Aspects Within the Cross-Cutting Areas,” dated December 19, 2013. All violations of NRC requirements are dispositioned in accordance with the NRC’s Enforcement Policy, dated July 9, 2013. The NRC’s program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, “Reactor Oversight Process,” Revision 5, dated February 2014
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Calvert Cliff: Exelon
Salem
Owner(s)
| Exelon (43%) PSE&G (57%) |
An apparent turbine-generator problem triggered an automatic shutdown of PSEG Nuclear's Salem Unit 1 along the Delaware River southeast of Port Penn Wednesday morning, the third unplanned shutdown at the operation in a month.
Neil Sheehan, spokesman for the Nuclear Regulatory Commission, said that the utility and federal regulators will investigate the 5 a.m. incident, but have already confirmed that the plant is "in a safe condition."
Workers shut down the same plant April 8 after a breakdown in a pump that sends condensed cooling water and steam from generating turbines back to steam-producing equipment.
Unit 1 also tripped off briefly April 13.
STORY: Salem reactor shuts down for second time in a week
STORY: Salem nuclear reactor shut down
NRC rules require stepped-up oversight for reactors that report three unplanned shutdowns within any 7,000 hour, or roughly nine-month, period of consecutive operations.
Salem 1 is the oldest of three reactors at PSEG's Salem/Hope Creek nuclear complex in Lower Alloways Creek, N.J., and was first licensed for operation in 1976. The Salem units can generate about 1,175 megawatts each, with the newer Hope Creek plant rated at 1,219 megawatts.
Salem Unit 2 is presently offline for refueling.
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