Salem, Hope Creek and Palisade Primary Coolant Pumps

Salem, Hope Creek and Palisades….

Tom Gurdziel

Good morning,

Tom Gurdziel tgurdziel@twcny.rr.com

Sunday, June 22, 2014 10:04 PM

CHAIRMAN Resource

Screnci, Diane

PSEG/Hope Creek Recirculation Pump B

1 recently stated that PSEG ran a troubled pump many hours past the recommended inspection interval, but I did not remember the specific numbers.

You will find the actual numbers in ML050100194. The inspection was recommended by GE SIL 459 at 80,000 hours. At the time this (ML) document was written, you will find in the second paragraph of page A-1 that Recirculation Pump B had been run 130,000 hours. How many it had when it actually got its shaft replaced, I do not know.

Thank you,

Tom Gurdziel

From: Screnci, Diane

Sent: Friday, June 20, 2014 8:34 AM

To: Tom Gurdziel; CHAIRMAN Resource

Subject: RE: PSEG/Salem 2 Reactor Coolant Pumps

Just an FYI- there was an event notification on Monday of last week http://www.nrc.gov/reading-rm/doccollections/ event-status/event/2014/20140609en.html, which prompted Bill Gallo's (and other) story. Also PSEG put out a press release about this in May, so there was news coverage then, as well.

Subject: RE: PSEG/Salem 2Reactor Coolant Pumps

Good morning,

Well, I just read about the Salem 2 bolt problem. (Bill Gallo, Jr./South Jersey Times.} It really wasn't hard to find on the Internet: as long as you already knew about the problem. If you didn't know, let me tell you, you weren't going to find it.

I have a couple of problems, and you should, too.

First off, is intergranular stress corrosion cracking iM their current pump aging management program, or didn't that start yet?

Second, since this is a PWR, (like the SONGS ones were}, does it also have a "loose parts monitor'' that had procedures that required no operator action no matter how many times a year, (like 30, that is a three and a zero}, the alarm comes it (as it did at SONGS)?

Third, would you think that some sort of information should have been provided by the US NRC to the public, or would that have been too transparent?

And, finally, you need to have someone explain to you how much trouble PSEG had at their Hope Creek plant a few years ago with a reactor recirculation pump that was run many thousands of hours past the vendors suggested (tear down) inspection time while they continued to monitor (but not fix) the excessive and unexpected (by them) pump vibration. My feeling is that they now should have been especially observant of problems on big pumps. Don't they do predictive maintenance on big pumps (and their motors)?

Thank you,

Tom Gurdziel

Mom & Dad had Public Service Electric & Gas, (now PSEG), stock since I was a kid. I have some of it now and am not happy with what I see here of continuing big pump problems.

Reactor Recirculation Pump Vibration Review

Background

The “B” Hope Creek reactor recirculation (RR) pump has had a historical problem involving

high vibration levels—about double those on the “A” RR pump. Past licensee actions to

reduce the vibration levels have not been effective. The high vibrations have been attributed,

in part, to a slight bowing of the shaft in the area below the seal package area. The vibrations

have led to frequent seal replacements (1.5-year intervals versus the expected 6-year

intervals).

In addition to the bowing, the “A” and “B” RR pump shafts are expected to have some degree

of thermally induced stress cracking based on industry operating experience described in GE

Service Information Letter (SIL) 459. GE SIL 459 recommends three actions to address this

problem: vibration monitoring, shaft inspections after about 80,000 hours of operation and

action to mitigate the thermal stress initiators. Hope Creek’s RR pumps have over 130,000

hours of operation, and PSEG has not performed the recommended inspections.

In addition to the pump vibrations, there are vibrations on the associated RR and RHR system

piping which have resulted in damage to system sub-components (MOV handwheel and limit

switches). To date none of the vibration-induced component problems have rendered any

safety-related system inoperable.

Sargent and Lundy (S&L) performed an independent assessment for PSEG which concluded

that return of Hope Creek to service for the next operating cycle was acceptable given the

current level of RR pump and piping vibrations. S&L’s conclusion was based upon data which

indicated that the vibration level for Hope Creek’s “B” RR pump was consistent with RR

pumps at other facilities and also based on an assumption that operators would be able to

respond to an increasing vibration trend and take action to remove the pump from service

prior to shaft failure.

The S&L assessment is summarized in the report, “Independent Assessment of Hope Creek

Reactor Recirculation System and Pump Vibration Issues,” dated November 12, 2004. The

staff reviewed the S&L report and developed a number of questions which were provided to

the licensee on December 1, 2004. PSEG responded to the questions during a December 17,

2004, public meeting with the NRC. PSEG provided an additional response to the staff

questions in a December 22, 2004, submittal. In addition, numerous teleconferences were

held between PSEG and the NRC in December 2004 and January 2005 to discuss the “B” RR

pump vibration issue.

The S&L Report concluded that there is no immediate need to replace the “B” pump rotor

during the current refueling outage. S&L recommended that both pumps be monitored for

vibrations and that a rapid rise in vibrations would be a sufficient reason to shut the pump

down immediately for an internal inspection and shaft replacement, as the window between

the rise in vibration and potential shaft failure is expected to be small.

A-2

PSEG also provided additional background information in Report H-1-BB-MEE-1878, “Hope

Creek ‘B’ Recirculation Pump Vibration Analysis,” Revision 1, dated December 16, 2004.

The report concluded that, while the “B” RR pump has elevated vibrations when compared to

the industry average, these vibration levels are not detrimental to the operation or reliability of

the pump. The report also indicated that, although the risk of a RR pump shaft cracking event

during any given cycle cannot be quantified, the operating experience of 29 RR pumps in

operation longer than the Hope Creek “B” RR pump provides sufficient data to conclude that

the risk of a shaft cracking event during the next cycle is minimal.

Staff Review

The staff review focused on the following key issues regarding the RR pump operation:

(1) Does PSEG have a technical evaluation which shows that the RR pumps can be

operated for another cycle without failure of the shafts considering the identification of

shaft cracks that have been observed at other facilities with the same design RR

pumps?

(2) Can PSEG provide data which demonstrates that shaft cracks have been detected at

other facilities with the same design RR pumps using vibration monitoring? Can the

cracks be detected in time for the operators to take appropriate actions?

(3) What are the consequences of a RR pump failure during plant operations?

GE SIL 459 indicates that all Byron Jackson RR pump shafts inspected have shown some

degree of thermally induced cracking. The cracking occurs near the pump thermal barrier

where mixing of cold seal purge system water and the hot reactor coolant water occur. The

cracks initiate as axial cracks in the pump shaft. The licensee indicated that, if the cracks

remain axial, the cracks will grow slowly and not affect the operation of the pump. However,

the licensee also indicated that given sufficient mechanical loads, the cracks can become

circumferential. The circumferential cracks can propagate to shaft failure under mechanical

loading. The time it takes to transition from slow growing axial cracks to more rapidly growing

circumferential cracks depends on the magnitude of the mechanical loads acting on the pump

shaft. Since the licensee does not know the magnitude of the mechanical loads, it is difficult

to predict the shaft life based on the magnitude of the operational loads.

The licensee has cited operating experience of other BWRs with similar Byron Jackson RR

pumps. The licensee indicates that the age of the Hope Creek RR pumps is about average

for the pumps of similar design at other BWRs. The staff notes that a number of the older

pumps included in the licensee’s comparison are much smaller than the Hope Creek pumps.

While the operating experience provides some confidence that the pumps can be safely

operated beyond the time interval recommended in GE SIL 459, the crack growth analyses

provided by the licensee indicate that the time is highly dependent on the magnitude of the

mechanical loads which are not well known.

A-3

The licensee also provided the level of vibration recorded at other BWRs with similar Byron

Jackson RR pumps. The licensee concluded that measured vibration levels of the Hope

Creek RR pumps are within the range of the vibration levels measured at other BWRs.

However, the level of vibration of the “B” pump is toward the high end of the range of vibration

levels measured at other BWRs. Therefore, the “B” pump is experiencing higher vibratory

loadings than most of the pumps in the licensee’s survey. In addition, the licensee cited a

history of problems in its attempt to balance and align the pump shaft. These problems

caused additional mechanical loadings on the pump shaft which could increase the potential

for circumferential cracks to have developed in the shaft. On the basis of the above

discussion, the staff concludes that the probability of a pump shaft failure of RR pump “B”

during the next cycle of operation is indeterminate based on PSEG’s evaluation of the

potential thermal and mechanical loads on the pump shaft.

The licensee relies on vibration monitoring to detect circumferential cracking of the RR pump

shaft with sufficient lead time for operators to secure the pump from complete shaft failure.

The licensee developed a plan for monitoring the vibration levels of the RR pumps. The key

elements of the plan involve continuous basic monitoring of the overall level of vibration and

continuous monitoring of the vibration harmonics for enhanced detection capability of potential

shaft cracking.

The licensee’s continuous basic vibration level monitoring by the operations department

consists of a pump vibration alarm and pump speed reduction if the “B” pump vibration level

reaches 11 mils (0.011 inch), and removal from service if the pump vibration level reaches 16

mils (0.016 inch). The continuous monitoring of the vibration harmonics consists of pump

vibration alarms and pump speed reduction if the synchronous speed (1X) vibration

amplitude, two times synchronous speed (2X) vibration amplitude, 1X phase angle, or 2X

phase angle exceed defined allowable limits. If the monitored values do not fall within their

allowable limits at the reduced pump speed, the licensee will remove the RR pump from

service. The allowable limits are established using ASME OM Standard, “Reactor Coolant

and Recirculation Pump Condition Monitoring.” The licensee will record baseline data to

establish these allowable limits during plant startup. The licensee provided two technical

papers in support of the proposed vibration monitoring criteria.

The first technical paper is entitled, “Case History Reactor Recirculation Pump Shaft Crack,”

Machinery Messages, December 1990. The paper discusses the RR pump shaft cracking

experience at the Grand Gulf nuclear power plant. The paper indicates that the vibration level

increased rapidly over a three hour period before the pump was secured at slow speed.

Although the shaft did not experience a complete failure, subsequent inspection revealed the

shaft was cracked approximately 320 degrees around the circumference. The paper indicates

that it is necessary to monitor the 1X and 2X steady state vectors (1X and 2X amplitudes and

phase angles) on a continuous basis and to compare these monitored values to an

acceptance criteria. The paper also indicates that alarms are necessary to alert the user to

amplitude and phase deviations that are outside the acceptance criteria.

The second paper is a Technical Bulletin from Bently, Nevada, “Early Shaft Crack Detection

on Rotating Machinery Using Vibration Monitoring and Diagnostics.” The technical bulletin

indicates that shaft cracking can be detected by monitoring the 1X and 2X vectors. The

technical bulletin also recommends continuous monitoring of machines that are susceptible to

shaft cracking.

A-4

These papers recommend using continuous monitoring of the 1X and 2X vectors as a

predictive method to detect significant shaft cracking. The staff requested that the licensee

provide some evidence that vibration monitoring was effective for detecting shaft cracks in RR

pumps similar to the Hope Creek RR pumps. The licensee cited the experience at Grand Gulf

discussed above. The Grand Gulf RR pump shafts are hollow shafts as opposed to the solid

shafts used in the Hope Creek RR pumps. Therefore, the Grand Gulf experience may not be

directly applicable to Hope Creek. The licensee provided additional information which

indicates that cracks in reactor coolant pump shafts were identified at Sequoyah (technical

presentation to NDE Steering Committee by G. Wade, July 12, 2002) and Palo Verde Unit 1

(Palo Verde Nuclear Generating Station Cracked Reactor Coolant Pump Shaft Event, H.

Maxwell, 1996) using vibration monitoring. Although these plants are Pressurized Water

Reactors (PWRs), the reactor coolant pumps have solid shafts. The licensee indicated that

these pumps had operated for a significant period of time after the first indication of shaft

cracks by vibration monitoring. A staff review also identified that vibration monitoring

successfully identified a reactor coolant pump shaft cracking at St. Lucie Unit 2 (LER Number:

1993-005). The PWR reactor coolant pump experience provides some indication that a solid

pump shaft will provide better early crack detection capability than the hollow pump shafts,

such as those used at Grand Gulf. PSEG has provided data which demonstrates that shaft

cracks in pump shafts similar to those used at Hope Creek have been detected at other

facilities, and that these cracks were detected in time for operators to take appropriate

actions.

On the basis of the available operating experience, the staff concludes that continuous

monitoring of the 1X and 2X amplitudes and phase angles provides reasonable assurance

that circumferential shaft cracking can be detected with sufficient time for the plant operators

to take appropriate actions. The licensee will either reduce the RR pump speed or remove

the pump from service if the monitoring system detects vibration levels that exceed the limits

specified in the vibration monitoring plan.

The staff also reviewed the licensee’s assessment of the potential consequences of a RR

pump shaft failure. The RR pump shaft axial cracking that has been reported occurred below

the seal area and above the pump hydrostatic bearing. This is the region where a potential

RR pump shaft failure would be expected to occur. The pump impeller would be expected to

settle at the bottom of the pump casing, which could potentially result in some damage to the

pump casing. The unsupported end of the upper part of a broken shaft may damage the shaft

seal. A seal failure would result in leakage of reactor coolant through clearances around the

upper half of the broken pump shaft. This leakage would be bounded by the design basis

small LOCA event. If such an event were to occur, the licensee would be able to isolate the

pump using the RR loop isolation valves, thereby terminating any reactor coolant system

leakage.

Conclusion

The staff concludes that the licensee’s continuous monitoring program for the Hope Creek RR

pumps, as discussed above, provides reasonable assurance that a potential crack in the RR

pump shaft can be detected in time for operators to take appropriate actions to reduce the

pump speed or remove the RR pump from service prior to a complete shaft failure.

B-1

Enclosure 2

High Pressure Coolant Injection (HPCI) Exhaust Line Review