Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
May 31, 1995
NRC INFORMATION NOTICE 95-26: DEFECT IN SAFETY-RELATED PUMP PARTS DUE TO
INADEQUATE HEAT TREATMENT
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to a potential for pump failure as a result of
inadequate heat treatment of pump parts. It is expected that recipients will
review the information for applicability to their facilities and consider
actions, as appropriate, to avoid similar problems. However, suggestions
contained in this information notice are not NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances
On October 19, 1994, Westinghouse issued a written report pursuant to Part 21
of Title 10 of the Code of Federal Regulations (Part 21) (Accession No.
9411010251), regarding a defect found in the "JHF" model safety injection
pumps that were manufactured by Ingersoll-Dresser Pump (IDP) Company. The
defect comprises several axial cracks in the pressure-reducing sleeve locknut,
which is made of Type 416 stainless steel. The failure mechanism was
attributed to stress corrosion cracking which primarily was caused by a
martensite phase hardness of 47 Rc (Rockwell Scale C). It is known that 400
series stainless steel with a hardness in excess of 40 Rc is highly
susceptible to intergranular stress corrosion cracking in aqueous
environments. The heat treatment for this pump part was specified to be
27-32 Rc.
Although the problem was at first thought to be limited to the locknut on the
pressure-reducing sleeve within the IDP pump, Westinghouse and IDP have
determined that other pump parts may be affected by the same problem. On
February 20, 1995, Westinghouse issued a final Part 21 report which indicated
that (1) in addition to the subject locknut, other pump parts could be
affected by the same problem and (2) the problem is limited to IDP pump parts
that were made of Type 416 stainless steel, processed under heat treatment
process "HT 21," and that were taken from heat numbers 15899 and 28144.
The detailed Westinghouse final Part 21 report (Accession No. 9503020053) on
this issue is attached (Attachment 1).
9505240309.
IN 95-26
May 31, 1995
Page 2 of 2
Discussion
As noted in the attached Westinghouse Part 21 report, the suspect parts are
used in intermediate-head safety injection pumps, auxiliary feedwater pumps,
and charging/high-head safety injection pumps in various plants. The defect
in these pump parts, if not corrected, could result in pump failure. The loss
of these pumps during a design-basis accident could affect accident
mitigation.
Some of these affected pumps have been in operation for more than 10 years.
Because of the importance of these pumps to plant safety, Westinghouse has
recommended that the affected pump parts be replaced with the parts currently
recommended by IDP.
An IDP safety injection pump (model "JTCH") failed during a post-maintenance
test at Indian Point Unit 3 on February 19, 1995. Inspection of the internal
components of the pump revealed that the locknut on the outboard shaft had
backed off about 6.35 mm [0.25 inch]. The loosened locknut allowed the pump
impellers to move axially, and allowed them to rub against the stationary
diffusers and the casing, and ultimately resulted in pump failure. Although
the root cause of this failure is unrelated to the problem reported by
Westinghouse, a similar pump failure could occur if the locknut on the
pressure-reducing sleeve, mentioned in the Westinghouse Part 21 report,
failed.
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
/s/'d by BKGrimes
Brian K. Grimes, Director
Division of Project Support
Office of Nuclear Reactor Regulation
Technical contacts: James A. Davis, NRR
(301) 415-2713
Peter C. Wen, NRR
(301) 415-2832
Attachments:
1. Westinghouse Part 21 Report, February 20, 1995
2. List of Recently Issued NRC Information Notices
. Attachment 1
IN 95-26
May 31, 1995
NTD-NRC-95-4403
Westinghouse Energy Systems Nuclear Technology
Division
Electric Corporation Box 355
Pittsburgh, Pennsylvania
15230-
0355
February 20, 1995
U.S. Nuclear Regulatory Commission
Attn: Document Control Desk
Washington, DC 20555
Subject: Update to 10CFR21 Report Contained in Westinghouse Letter NTD-
NRC-94-4320, dated 10/19/94 and Status Report Contained in
Westinghouse Letter NTD-NRC-94-4361, dated 12/21/94
Reference: 1. Letter NTD-NRC-94-4320, N. J. Liparulo to Document Control
Desk, 10/19/94
2. Letter NTD-NRC-94-4361, N. J. Liparulo to Document Control
Desk, 12/21/94
3. Westinghouse Nuclear Safety Advisory Letter, NSAL-94-023,
10/26/94
The following information is provided as an update to the 10 CFR 21 report
that was previously identified to you in References 1 and 2.
BACKGROUND
Reference 1 identified a defect, as defined under 10CFR21, regarding the
pressure reducing sleeve locknut of the JHF Model Safety Injection Pump that
was manufactured by Ingersoll Dresser Pump (IDP) Company and supplied to
several nuclear power plants by Westinghouse and IDP. Westinghouse also
notified the affected licensees about the defect via Reference 3.
Reference 1 indicated that IDP would perform a review of the applicable 400
series stainless steel parts and applicable heat treatments on other safety
related pumps it supplied to the nuclear power industry to determine whether
this situation could apply to other parts on other safety related pumps. This
review was completed on December 15, 1994.
Westinghouse notified the NRC about the results of this review via Reference
2. The results of the review indicated that the failure mechanism appears to
be limited to IDP pump parts that consist of 416 SS, processed under IDP heat
treatment process "HT 21" and taken from IDP heat numbers #15899 and #28144.
Also, the review indicated that additional pump parts may be susceptible to
the same failure mechanism. Reference 2 indicated that IDP would determine
whether the failure of the additional pump parts would prevent the applicable
pump from performing its intended safety function.
This review has been completed and indicates that some of the additional pump
parts may also constitute a defect, as defined in 10 CFR 21, which could
create a substantial safety hazard. The following report provides more
information about these additional pump parts.
.EVALUATION
IDP's evaluation results indicate that all 416 SS parts processed under IDP
heat numbers #15899 and #28144 are susceptible to the same failure mechanism
as the pressure reducing sleeve locknuts. These parts have been divided into
three categories.
The first category includes parts which were supplied with the original pump
assembly and whose failure could prevent the pump from performing its intended
safety function. These parts and the applicable plants are identified in
Table 3. Also, note that these parts include the pressure reducing sleeve
locknuts that were the parts originally identified in Reference 1.
The second category includes parts which were supplied with the original pump
and whose failure would not prevent the pump from performing its intended
safety function. These parts are identified in Table 4. The parts should be
replaced as a prudent maintenance activity. It should be emphasized that
these parts do not constitute defects pursuant to 10 CFR 21 since the failure
of the parts should not prevent the pump from performing its intended safety
function. However, they are included in this letter to identify the results
of the evaluations that are mentioned in References 1 and 2.
The third category includes the parts which were supplied as replacement pump
parts and whose failure could prevent the pump from performing its intended
safety function. Most of the replacement parts were supplied directly to the
utilities by IDP. These parts and the applicable plants are identified in
Table 5. Please note that Table 5 has been divided into two lists. One list
("Parts from Identified Material") includes the replacement parts that are
known to have been taken from heat #15899 and #28144. The other list ("Parts
from Unidentified Material") includes those parts which could have been
manufactured from either heat #15899 or #21844, based on the time of
manufacture, original material specification and part size. However, there is
no documentation to specifically identify the heat number from which the part
was taken. Therefore, it was assumed that the parts were taken from heat
#15899 and #21844.
The identification of the parts in Tables 3, 4 and 5 is based on several
reported part failures, a failure analysis of failed parts and engineering
judgement. Duke Power Company reported two separate failures (cracking) of
the pressure reducing sleeve locknuts on JHF model safety injection pumps.
Both locknuts consisted of 416 SS and were processed under heat #15899. Duke
Power performed a failure analysis on each locknut. The failure analysis
indicated that the failure mechanism was stress corrosion cracking. The
analysis also indicated that each locknut's susceptibility to stress corrosion
cracking was increased by a relatively high martensite phase hardness which
allegedly resulted from an insufficient tempering operation. A comparison of
the Duke Power Failure analysis report and the IDP heat treatment
specification and heat material certification is provided in Table 1.
Table 1: Pressure Reducing Sleeve Locknut - Comparison of Duke Power Company
Failure Analysis to IDP Heat Treatment Specification and Material
Certification..Hardness (Rc)..First Locknut.Second Locknut.Failure Analysis - Bulk Phase.35.32-33.Failure Analysis - Microhardness.45-49.42-44.Heat Treatment "HT21" Specification.27-32.Heat #15899 Material Certification Bulk
Phase Hardness.27.The existence of two failures and the data in Table 1 provide a basis to
conclude that the locknuts are defects as defined in 10 CFR 21. First, it
should be noted that 400 series SS with a hardness of greater than 40 Rc is
very susceptible to intergranular stress corrosion cracking in aqueous
environments. Table 1 indicates that for both locknuts, the microhardness was
higher than 40 Rc. Also, Table 1 indicates that for both locknuts, the bulk
phase hardness measured in the failure analysis was significantly higher than
the bulk phase hardness provided on the material certification sheet. It
could not be determined why these bulk phase hardness values are different.
Since, the microhardness was greater than 40 Rc, the bulk phase hardness
difference could not be attributed to any specific reason. However, since the
cracking was observed on each locknut, it was determined that all parts from
heat #15899 could be susceptible to the same failure.
In addition to the above, Duke Power Company recently discovered cracking on a
spacer sleeve in another JHF model safety injection pump. The spacer sleeve
consisted of 416 SS and was processed under IDP heat treatment specification
"HT 21". However, the spacer sleeve was taken from a different heat, which
was heat #28144. Duke Power performed a failure analysis on the spacer sleeve
and determined that the failure mechanism was also stress corrosion cracking.
Also, the failure analysis indicated that the spacer sleeve's hardness made
the sleeve marginally acceptable for service in aqueous environments. A
comparison of the Duke Power Failure analysis report and the IDP heat
treatment specification and heat material certification for the spacer sleeve
is provided in Table 2.
Table 2: Impeller Spacer Sleeve - Comparison of Duke Power Company Failure
Analysis to IDP Heat Treatment Specification and Material Certification
..Hardness (Rc).Failure Analysis - Bulk Phase.26-30.Failure Analysis - Microhardness.33-39.Heat Treatment "HT21" Specification.27-32.Heat #28144 Material Certification - Bulk
Phase Hardness.27
The existence of the cracked spacer sleeve and the data in Table 2 provide a
basis to conclude that the spacer sleeve is a defect as defined in 10 CFR 21.
First, the measured microhardness of 33-39 Rc is higher than the material
certification value of 27 Rc. It is less than 40 Rc, but nonetheless is
marginally susceptible to stress corrosion cracking in aqueous environments.
The bulk phase hardness range is somewhat higher than the material
certification value, but it is still within the heat treatment specification
range of 27-32 Rc. Based on this information, it was concluded that all parts
used from heat #28144 could be susceptible to the same failure mechanism.
Finally, and as mentioned, Tables 1 and 2 indicate that there is some
difference between the bulk phase hardness value and the material
certification values. There are no apparent reasons for these differences.
Furthermore, Tables 1 and 2 indicate that there are significant differences
between the bulk hardness and the microhardness values. There are no apparent
reasons for these differences; however, it may be postulated that the
differences are attributable to insufficient tempering. IDP has not received .any additional reports of part failures involving 416 SS under heat treatment
specification "HT21". Therefore, it was concluded that the failures should be
limited to only those parts that were taken from heats #15899 and #21844.
Table 3 identifies all pump parts that were originally supplied with a pump,
taken from heat #15899 and #28144 and whose failure could prevent the
applicable pump from performing its intended safety function. Table 4
identifies the parts that were originally supplied with a pump, taken from
heat #15899 and #28144 and whose failure would not prevent the pump from
performing its intended safety function. However, it is recommended that the
parts in Table 4 be replaced as a prudent maintenance practice. Finally,
Table 5 identifies the replacement pump parts that were either supplied or
believed to have been supplied from heat #15899 and #28144 and whose failure
could prevent the applicable pump from performing its intended safety
function.
SAFETY SIGNIFICANCE
The safety significance for the failure of each part identified in Tables 3, 4
and 5 is provided as follows. The failure of the parts in Tables 3 and 5
could prevent the pump from operating. For Table 4, the part failure should
not prevent the pump from operating. More detailed information for the parts
identified in Tables 3, 4 and 5 will be provided directly to each utility.
The pumps identified in Table 3 are all JHF model safety injection pumps.
These pumps are used in the intermediate head safety injection system for the
applicable plants. The loss of these pumps during the short term mitigation
period of a loss of coolant accident (LOCA) would impair the plant's ability
to mitigate the consequences of the LOCA. The loss of the pump (or pumps)
would reduce the overall flow to the core, which could create a condition that
is a substantial safety hazard.
The pumps identified in Table 5 include the intermediate head safety
injection, auxiliary feedwater, and charging/safety injection pumps. The
intermediate head pumps are discussed above. The auxiliary feedwater pumps are
used to provide feedwater to the steam generators during certain accident
conditions. The loss of these pumps during a feedwater line break accident
would impair the plant's ability to recover from the break. The loss of the
pump (or pumps) would reduce the available secondary side cooling, which could
create a condition that is a substantial safety hazard.
The charging/safety injection pumps are used in the high head safety injection
system for the applicable plants. The loss of these pumps during the short
term mitigation phase of a LOCA would impair the plant's ability to mitigate
the consequences of the LOCA, especially for a small break LOCA. The loss of
the pump (or pumps) would reduce the overall flow to the core, which could
create a condition that is a substantial safety hazard.
RECOMMENDATIONS
The following recommendations are provided for this issue.
1. Review Tables 3, 4 and 5 to determine whether the plant has any parts
that could be affected by this failure mechanism. The parts identified
in Table 3 and 5 are considered defects as defined in 10 CFR 21.
Although the parts in Table 4 are not considered defects pursuant to 10
CFR 21, the parts in Table 4 should eventually be replaced as a prudent
maintenance practice since these parts are susceptible to the same
failure mechanism.
2. Compare the information for the part in Tables 3, 4 and 5 to determine
whether the part is currently installed on the pump. In some cases,
this part may have been changed after the part was supplied..3. For parts in Table 3 and 5, if it is determined that the pump part is
currently installed on the pump, then the following should be
considered. First, as indicated in Table 5, if the affected part is a
shaft sleeve compression nut or a shaft sleeve collar, the part can be
inspected for cracking without disassembly of the pump.
Alternatively, if the affected part can not be inspected without
disassembly of the pump and it is not practical to immediately
disassemble the pump, then the pump operating history should be reviewed
relative to the mechanism for stress corrosion cracking. The mechanism
for stress corrosion cracking is dependent upon several factors
including, but not limited to, the amount of stress placed on the part,
the time the part is exposed to that stress, the time exposed to an
aqueous environment and the physical dimensions of the part. By
reviewing these factors, it may be possible to demonstrate that the part
failure is not imminent and/or that the part will not fail in a manner
that will prevent the pump from performing its intended safety function.
However, it is ultimately recommended that the part be replaced with the
part currently recommended by IDP.
The above information is being concurrently transmitted to affected utilities
via supplement to Westinghouse letter NSAL-94-023.
If you have any questions regarding this transmittal, please contact H. A.
Sepp of my staff on 412/374-5282.
Very truly yours,
ORIGINAL SIGNED BY
N. J. Liparulo, Manager
Nuclear Safety Regulatory and Licensing Activities
JWF/p
cc: R. E. Joines/IDP
G. Morrissey/IDP. TABLE 3
ORIGINAL CONSTRUCTION PUMP PARTS FROM HEAT #15899 AND
#28144
Utility.Units.Pump Model/Serial #.Part.Year Shipped.Kansai.Ohi 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49347
49348
49349
49350.Impeller Locknut
Pressure Reducing
Sleeve Locknut
Spacer Sleeves.1975.TVA.Watts Bar 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49351
49352
49353
49354.Impeller Locknut
Pressure Reducing
Sleeve Locknut
Spacer Sleeves.1975.Duke Power.McGuire 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49355
49356
49357
49358.Impeller Locknut
Pressure Reducing
Sleeve Locknut
Spacer Sleeves.1975.Duke Power.Catawba 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49359
49360
49361
49362.Impeller Locknut
Pressure Reducing
Sleeve Locknut
Spacer Sleeves.1976.Commonwealth
Edison.Braidwood 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49762
49763
49764
49765.Impeller Locknut
Pressure Reducing
Sleeve Locknut
Spacer Sleeves.1978. TABLE 3 - continued
ORIGINAL CONSTRUCTION PUMP PARTS FROM HEAT #15899 AND
#28144
Utility.Units.Pump Model/Serial #.Part.Year Shipped.Commonwealth
Edison.Byron 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49758
49759
49760
49761.Impeller Locknut
Pressure Reducing
Sleeve Locknut
Spacer Sleeves.1978.Public Service of
Indiana.Marble Hill 1 & 2.JHF 10 Stage (Service
Unknown)
49754
49755
49756
52079.Impeller Locknut
Pressure Reducing
Sleeve Locknut
Spacer Sleeves.1978.Wolf Creek Nuclear
Operating Company.Wolf Creek .JHF 11 Stage
(Intermediate Head
Safety Injection)
51647
51648.Spacer Sleeves.1977.Aerojet Nuclear.Bettis Atomic
Power Lab.JHF 10 Stage (Service
Unknown)
49756.Impeller Locknut
Spacer Sleeves.1976
. TABLE 4
ORIGINAL CONSTRUCTION PUMP PARTS FROM HEAT #15899 AND
#28144,
REPLACEMENT OF PART IS NOT MANDATORY
Utility.Units.Pump Model/Serial #.Part.Year Shipped.Kansai.Ohi 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49347
49348
49349
49350.Split Rings.1975.TVA.Watts Bar 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49351
49352
49353
49354.Split Rings.1975.Duke Power.McGuire 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49355
49356
49357
49358.Split Rings.1975.Duke Power.Catawba 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49359
49360
49361
49362.Split Rings.1976
. TABLE 4 - continued
ORIGINAL CONSTRUCTION PUMP PARTS FROM HEAT #15899 AND
#28144,
REPLACEMENT OF PART IS NOT MANDATORY
Utility.Units.Pump Model/Serial #.Part.Year Shipped.Commonwealth
Edison.Braidwood 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49762
49763
49764
49765.Split Rings.1978.Commonwealth
Edison.Byron 1 & 2.JHF 10 Stage
(Intermediate Head
Safety Injection)
49758
49759
49760
49761.Split Rings.1978.Public Service of
Indiana.Marble Hill 1 &
2.JHF 10 Stage (Service
Unknown)
49754
49755
49756
52079.Split Rings.1978.Wolf Creek
Nuclear Operating
Company.Wolf Creek 1.JHF 11 Stage
(Intermediate Head
Safety Injection)
51647
51648.Split Rings.1977.Aerojet Nuclear.Bettis Atomic
Power Lab.JHF 10 Stage (Service
Unknown)
49756.Split Rings.1976
. TABLE 5
REPLACEMENT PUMP PARTS FROM HEAT #15899 AND
#28144
Utility.Units.Pump Model/Serial #.Part.Year Shipped.Parts from Heat 15899 and 28144 (See Note 1).Commonwealth
Edison.Zion 1.JTCH 10 Stage
(Auxiliary Feedwater)
45796.Impeller Locknut
Shaft Sleeve
Compression Nut
Rad
Shaft Sleeve
Compression Nut
Thr.11/18/75.Parts from Unidentified Material (See Note 1).Alabama Power.Farley 2.IJ 11 Stage
(Charging/Safety
Injection)
47669.Shaft Sleeve
Collar.10/13/78.Commonwealth
Edison.Zion 1.JTCH 10 Stage
(Auxiliary Feedwater)
45796.Impeller Locknut
Rad.4/29/75.Commonwealth
Edison.Zion 1.JTCH 10 Stage
(Auxiliary Feedwater)
45796
45797.Impeller Locknut
Rad.9/16/77.Consolidated
Edison.Indian Point.JTCH 10 Stage (Safety
Injection)
43461
43466.Impeller Locknut
Rad
Shaft Sleeve
Compression Nut.8/11/76.Duquesne Light.Beaver Valley 1.IJ (Charging/Safety
Injection)
46351.Shaft Sleeve
Collar.9/3/76.Indiana Michigan
Power.Cook 2.IJ (Charging/Safety
Injection)
45607.Shaft Sleeve
Collar.9/3/76. TABLE 5 - continued
REPLACEMENT PUMP PARTS FROM HEAT #15899 AND
#28144
Utility.Units.Pump Model/Serial #.Part.Year Shipped.Kansai Electric.Ohi 1 & 2.IJ (Charging/Safety
Injection)
48586
48589.Shaft Sleeve
Collar.5/31/78.Northern States
Power.Praire Island 1
& 2.UNI 11 Stage (Auxiliary
Feedwater)
46578
46581.Impeller Locknut
Pressure Reducing
Sleeve Locknut.12/29/76.Portland General
Electric.Trojan.IJ (Charging/Safety
Injection)
45603.Shaft Sleeve
Collar.10/4/77.Pacific Gas &
Electric.Diablo Canyon
#2.JTCH 10 Stage (Safety
Injection)
45489.Shaft Sleeve
Compression Nut.12/30/77.Public Service
Electric and Gas.Salem 1.JTCH 10 Stage (Safety
Injection)
45493.Shaft Sleeve
Compression Nut.11/14/79.Public Service
Electric and Gas.Salem 2.IJ 11 Stage
(Charging/Safety
Injection)
45613.Shaft Sleeve
Collar.9/6/77.Public Service
Electric and Gas.Salem.IJ 11 Stage
(Charging/Safety
Injection)
45603.Shaft Sleeve
Collar.1977.Public Service
Electric and Gas.Salem 1.JTCH 10 Stage
45493
45494.Shaft Sleeve
Compression Nut.2/2/78
Notes:
1. This Table is divided into two sections. The first section titled "PARTS
FROM HEATS 15899 OR 28144" are those parts identified in the record search as
having come from material heat 15899 or 28144. The second section titled
"PARTS FROM UNIDENTIFIED MATERIAL" are those parts which could have been
manufactured from either heat based on time of manufacture, original material
specification, part size, etc., but for which there is no documentation on the
material used.
