Playing Games At Palisades for Decades With Primary Coolant Pumps

THE COVER UP

Right, if Palisades nuclear plant was a person. He could cold bloodily shoot somebody dead. If he could remain at large in the community in excess of three years...the rules say nobody could charge him for any crime or NRC violation. All he’s got to do is get away with for three years without being caught. 

 

The agency habitually has the inability to connect the dots. This is a NRC cover up. The NRC only presents the happy ever after story. From the event date of Oct 2011 to the inspection report of Aug 2012, the potential of a severe accident was right around the corner. We could had three seals fails out of four with severe pump impeller or worst damage in 1984...a much worst accident was right around the corner any time operating outside the FSAR and improper quality reactor component parts The accident could begine any time a huge impeller blade sloughs off.

2012 inspection report: Additionally, pieces suspected to be from impellers were discovered in the bottom of the reactor vessel in 1984 and 2007.  

Why didn’t the agency and the big dog NRR connect the dots between the 1984 and 2011...to disclose to the public that operating these components outside the FSAR could lead to a severe event like 1984? Does the agency get to pick and choose what information it release to make Palisades looks good? Just put the best face on any terrible event Palisades creates for themselves, the Industry and the nation?

So this is the pattern of the agency and Palisades picking the happy land information to release to the public. Putting a grossly inaccurate spin on actual and potential events at these plants. You are intention miscommunicating risk to the public and not demanding a change in behavior according to real risk the community faces with Palisades. 

So in 1984 the plant was ascending up in power to 57% when a broken impeller almost seized up the motor. God know how long the pump was "knowingly" operating contrary to the FSAR and equipment designs in 1984 when stresses threw off a big hunk of impeller blade. The severely unbalanced impeller tore off the cap screws and the two guide pins. The impeller wobbled around inside the pumps casing for many hours with only the remaining guide pins attaching the impeller to the safety.

Additionally, pieces suspected to be from impellers were discovered in the bottom of the reactor vessel in 1984 and 2007.

Man, I 'd like to be at that plant in 1984. To see that cloud of metal shards, missing cap screws and pieces of casing circulating around in the coolant like sandblasting the fuel pins and steam generators for months. Anyone find the cap screws yet? Didn't a RCP go crazy in the China Syndrome?




****Now I get it...these were on the secondary side...do they report what they find in the primary inlet side?

I'd certainly like to see the coolant activty record and the record of fuel pin failure over these years.

STEAM GENERATOR TUBE INSPECTION REPORT for the 2012 REFUELING OUTAGE, 1R22, EC39067

There are three tubes in SG E-50A that were removed from service preventively in contact with a loose part at the top of the hot leg tubesheet (TSH) in Row 130 Column 61, Row 132 Column 61, and Row 133 Column 62.

These guys are funny...they don't remove the loose part. They aren't interest in what broke?

These tubes had no wear indications from the loose part but were stabilized and removed from service by tube plugging to prevent issues due to wear from the loose part in the future.

 

So the worst accident I see is a LOCA through the failure of the pump mechanical seals and the destruction of the pump casing. The largest size hole of the Reactor Coolant Pump Loop pipe.

These guys are operating way out of their stated risk analysis and this is a cover-up of it. The secrecy and lying creates this opportunity.

Hell, it is probably not illegal to tell the public the probability of an accident is this to their face, then to conspire to operate these plants at a much higher accident risk level behind the scenes. It is just probably illegal just to tell the truth.

I am saying, if Palisades is the model for honesty and integrity throughout the NRC and the Nuclear industry, then a accident of infinite consequences could be right around the corner.

UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555

January 15, 1985

Information Notice No. 85-03:   SEPARATION OF PRIMARY REACTOR COOLANT PUMP SHAFT AND IMPELLER

Addressees:

All pressurized water power reactor facilities holding an operating license (OL) or construction permit (CP).

Purpose:

This information notice is provided to alert recipients of an event  involving primary reactor coolant pump impeller separation from the pump  shaft. It is expected that recipients will review the information for applicability to their facilities and consider actions, if appropriate, to  preclude similar problems occurring at their facilities. However, suggestions contained in this information notice do not constitute NRC requirements and, therefore, no specific action or written response is required.

Description:

On September 16, 1984, the Palisades Nuclear Plant had been operating for approximately three days in the process of initial power ascension following a refueling outage...

IR2012003: The research concluded that the cause of the failures is fatigue-related effects from the operation of the pumps in conditions beyond the maximum flow rates and below the minimum net positive suction head recommendations as described in the UFSAR and other design documentation. These conditions are present when operating only one or two PCPs during reduced temperatures and pressures (typically during startup and shutdown activities.

...The plant was at approximately 57 percent power. At 3:45 a.m. (EDT), reactor coolant pump (RCP) seal cavity pressures indicated that the first (lower) and second (middle) seals had failed simultaneously, and an orderly shutdown was commenced. At 5:20 a.m., the third (upper) seal failed. The reactor was taken off-line and, at approximately the same time, the pump vibration level reached the "danger" level (10 mils). The pump was then secured. In the 3-hour period prior to securing the pump, the electric current to the pump had increased by approximately 10 to 15 percent.

Inspection Report 2012003 references this 1984 event. Why didn't the NRC disclose in the 2012003 this severe seal and pump damage was a possibility till the replacement? Were they prettying up the engineering certainty-uncertainty? Did the Offices of Research and Nuclear Reactor Regulation in 2011 till the next outage consider the 1984 event as a possible acceptable and a safe outcome to the 2012 outage? Without question, the NRC considers the mysterious 1984 event as a sentinel issue...a cornerstone.

(2012003: "The licensee identified impeller cracking had been observed at Palisades on several occasions since 1984, when the pumps had been removed for inspection and refurbishment/replacement. Additionally, pieces suspected to be from impellers were discovered in the bottom of the reactor vessel in 1984 and 2007")

During the event, the flow in the loop driven by the affected pump remained normal. During the examination to determine the extent of the seal failure and to evaluate required repair, major damage to pump components was discovered. The bolts and guide pins that secure the impeller to the shaft had been severely damaged. Unexpected wear on the pump impeller/shaft assembly and pump internals was found. The impeller is normally fastened to the shaft by eight cap screws and four guide pins. However, when the pump was examined, all eight cap screws and two of the four guide pins were found broken. The impeller had been kept in rotation by the two guide pins that had remained intact. Stationary pump parts showed unexpected wear in 360 degrees of arc; rotating pump parts showed wear in 180 degrees of arc.

It is amazing. The NRC has allowed this plant simultaneously for decades to run outside the FSAR and with poor quality impellers.

The RCP at Palisades is a Byron Jackson 850 rpm, single stage, centrifugal pump 1 with a 42-inch diameter impeller and a 4,000-hp Allis-Chalmers motor. The pump has four seal stages with controlled bleed off (and no seal injection) for cooling. Because an impeller was damaged during 1983 by an apparently unrelated failure, another impeller and pump shaft assembly was installed as a unit in February 1984.(Come on, the 1983, 1984 and 2011 event were all related and caused by the same issue. Running this system not according to the FSAR and causing damaging vibrations and fatigue.) Procedures prescribed by the pump manufacturer were, followed for the installation of the impeller/shaft assembly; however, no manufacturer's representative was present when the installation took place. This assembly had been stored horizontally in the plant store room for approximately 12 years after it had been used in the 1972 time-frame during initial hot functional testing. It is this impeller/shaft assembly that failed on September 16, 1984, after the pump had accumulated approximately 1,300 hours running time before the event.

(Did you catch between the official notification and the update this shifted from a single impeller issue into a common cause issue...from the utility's fault to a manufacturer issue effecting many impellers.)

The analysis of the failure of the eight cap screws and the two guide pins indicated that failures resulted from fatigue and impact loading. The two out of four guide pins that did not fail were bent, which caused the pump shaft to be forced upward and the impeller to be forced downward. No bolt corrosion was found. Although a sheared RCP shaft occurred at Surry 1 in November 1973 as a result of a manufacturing defect, the event described here is the first involving the potential separation of a primary coolant pump impeller from its shaft.

Discussion:

Events leading to the pump impeller/shaft failure cannot be precisely determined; however, examinations of the cap screws indicate that abnormal stress caused them to fail. It is believed that the pump impeller/shaft assembly caused the abnormal cap screw stresses that ultimately led to the failure. It is now believed that the improper torquing of the pump screws was the root cause.

The event and the above conclusion regarding the cause of the failure raise three issues which should be emphasized. (1) Disassembly and reassembly of primary reactor coolant pumps is an operation which should be done in a rigorous manner employing manufacturer's recommendations and proper procedures. (2) The nearly simultaneous failure of the two seal stages is indicative of the seal package under abnormal stress. This stress, concurrent with high pump vibration is indicative of possible severe pump damage. Operator response to these indications led to the pump being shut down before the final two guide pins failed, thus, preventing a more severe event. This action was a prudent response to the situation. (3) Although the event described here is apparently isolated, it demonstrates the credibility of a pump failure event which could lead to a rapid flow decrease transient of the type expected with a sheared shaft event. Most PWRs have a licensing basis analysis for that event or the similar seized rotor event. These analyses generally assume an automatic response of the plant's reactor protection system which generates a reactor trip as a result of low reactor coolant flow.

IE INFORMATION NOTICE NO. 85-03, SUPPLEMENT 1: SEPARATION OF PRIMARY REACTOR COOLANT PUMP SHAFT AND IMPELLER

IE Information Notice 85-03 described an event at the Palisades Nuclear Plant involving the separation of the primary reactor coolant pump impeller from the pump shaft during operation. That notice stated that electric current to the pump increased by approximately 10 to 15 percent in the 3-hour period prior to securing the pump. Subsequent information received from the licensee indicates this current increase did not occur.

The postulated cause of the Palisades' cap screw failure was fatigue about brought by preload on the bolts insufficient to resist cyclic loading. This is believed to have been caused by the poor surface condition of the cap screw threads. This condition resulted in the specified torque values not being sufficient to properly preload the cap screws that join the impeller to the shaft in 1971. This situation suggests two points that should be stressed. First, the failure described in IN 85-03 was not caused by improper disassembly and reassembly of the reactor coolant pump; rather, the problem apparently occurred during initial assembly. Second, the cause of under tightening of the cap screws was the poor (rough) surface condition of the screw threads themselves. Thus, use of the torque to measure axial bolt loading was, in this case, misleading.

See, between the OE and NRC information, it is all unreliable crap information. Nothing agrees!

OE13604, Palisades, Byron Jackson/Flowserve: Three cracks were found in a primary

coolant pump impeller that was removed for refurbishment during the 2001 refueling

outage. The three cracks were similar in nature; each started on a separate impeller vane at

the suction side of the vane tip near the hub and then transverses in the vane in a linear

fashion. Prior to the removal of the pump, the pump exhibited no symptoms that would

indicate the presents of the cracks.

***The root cause concluded that a combination of increased residual stresses, caused by a lack

of the proper post weld heat treatment at the manufacturing facility, and high stress risers,

due to poor fabrication practices, allowed the stresses associated with the starting and

stopping of the pump to initiate fatigue-type cracks on the impeller vanes.

Based on Flowserve's evaluation, the cracks initiate perpendicular to the vane leading edge

and completely penetrate the vane. Most of the cracks have propagated back into the vane

and appear to self-arrest in the thicker vane cross-section. In a few cases the crack

propagated in a semi-circular direction. In one case the semi-circular section was lost from

the impeller. A piece approximately 3" by 6" was found in the reactor vessel. No evidence

of ISCC attack has been observed. The problem was caused by lack of post weld heat

treatment for repairs that were made during post manufacturing.

The stuck piece of impeller in the core today: "The metal is 5 inches by 12 inches long".

A means for external monitoring and detection of this condition does not exist. Impeller

cracking can only be determined by removal of the impeller from the pump, chemical

decontamination, and inspection by visual and liquid penetrate examination techniques. The

cracks are not detectable without removal of the oxide layer from the impeller by chemical

decontamination.

Flowserve recommends that pump impellers in excess of 175,000 hours of service (-20

years of running service) be removed and inspected for cracking to preclude in-service

failure. However, they have found cracking as early as 13 years. Davis-Besse has replaced

all four reactor coolant pump rotating elements in 1986 as due to issues with the RCP shaft

cracking. Preliminary estimate of the operation time for these impellers is estimate at

-103,000 hours (-12 years).

Review of the Acceptance Data Package for the 4 rotating elements that were installed in

1986. Tle Data Packages shows that all 4 impellers had weld repairs performed without

post-heat treatment. It is preferred that the currently install impellers should be refurbish

due to less starts on these than the current spares.