IR 05000335/1993008
| ML17228A127 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 04/12/1993 |
| From: | Blake J, Kleinsorge W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML17228A125 | List: |
| References | |
| 50-335-93-08, 50-335-93-8, 50-389-93-08, 50-389-93-8, NUDOCS 9304210197 | |
| Download: ML17228A127 (12) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTASTREET, N.W.
ATLANTA,GEORGIA 30323 Report Nos.:
50-335/93-08 and 50-389/93-08 Licensee:
Florida Power and Light Company 9250 West Flagler Street Hiami, FL 33102 Docket Nos.:
50-335 and 50-389 License Nos.:
DPR-67'and NPF-16 Facility Name:
St.
Lucie I and
Inspection Condu te rc
,
1993 Inspector:
W.
R 1ein or
. E.
ns ector D
e Si ned Approved by:
J J.
1'ake, Chief ate ials and Processes Section Engineering Branch Division of Reactor Safety
/2 P'3 Date Signed SUHMARY Scope:
This special announced inspection was conducted onsite to evaluate the licensee's activities related to the leak identified Harch 2, 1993, in the Unit 2 Pressurizer.
Results:
This inspector identified multiple examples of failure to incorporate or failure to properly incorporate ASHE B&PV Code requirements into instructions and procedures for the accomplishment of the temper bead weld repair to four Pressurizer one inch vapor space nozzles.
These discrepancies went undetected by the authors and all the reviewers at the Nuclear Steam Supply System supplier, ASEA Brown Boveri/Combustion Engineering, as well as all the licensee's reviewers including the St.
Lucie Facility Review Group.
The end result of above discrepancies and oversights was the failure to accomplish the temper bead weld repair to the four Pressurizer nozzles in accordance with the ASHE Code.
93042iOf97 9304i3 PDR ADOCK 05000335
This issue discussed in Paragraph Nos. 2b(l)
and 2b(2), demonstrates multiple failures relating to the control of contractors and related activities; review and approval of contractor progress at the site; understanding of the ASIDE B&PV Code requirements by the NSSS organization and by FPL Welding Engineers, NDE Engineers, Codes and Standards Sections, and guality organizations.
One violation was identified concerning failures to control welding (paragraph 2c).
REPORT DETAILS 1.
Persons Contacted Licensee Employees
- R. Boggs, JPN/ESI
- G. Bossy, Plant General Manager
- J. Brady, Mechanical Maintenance
- R. Dawson, Maintenance Manager K. Craig, Steam Generator Program Manager
- J. Dyer, guality Control (gC) Supervisor
- R. Englmeier, Site guality Manager
- J. Holt, Licensing Engineer
- L. HcLaughlin, Licensing Manager
- A. Menocal, Mechanical Maintenance Department Head
- D. Sager, Site Vice President
- J. Scarolia, Site Engineering Manager
- T. Skiba, ESI
- J. West, Licensing Manager
- W. West, Technical Department Manager Other licensee employees contacted during this inspection included engineers, mechanics, security force members, technicians, and administrative personnel.
NRC Resident Inspectors
- S. Elrod, Senior Resident Inspector H. Scott, Resident Inspector
- Attended exit interview Acronyms and initialisms used throughout this report are listed in the last paragraph.
2.
Pressurizer Leak a ~
Background In February, 1986, the Southern California Edison (SCE)
San Onofre Nuclear Generating Station (SONGS) Unit 3 experienced a pressurizer vapor space leak in one of the partial penetration weld instrument nozzles.
Review indicated that the SONGS nozzles were ASME SB-166 Inconel Alloy 600, Heat No. 54318.
Failure analyses revealed that this heat of material had metallurgical properties that made it susceptible to Primary Water Stress Corrosion Cracking (PWSCC).
During the SCE review it was discovered that St. Lucie Unit 2 had
instrument nozzles of similar design and fabricated from the same
heat (54318) of Inconel Alloy 600 material.
These nozzles were located as follows:
Pressurizer vapor space four nozzles; Pressurizer liquid space one nozzle; Reactor Coolant System (RCS)
hot leg five RTD nozzles; RCS cold leg four RTD nozzles; and reactor vessel flange leak detection system two nozzles.
FPL performed an engineering evaluation to predict the time until the
installed St. Lucie nozzles would leak using the Arrhenius relationship.
This model projects a time to failure at a given temperature from a known time to failure at a known temperature for a specific Heat of material.
The model relationship is as follows:
Where:
t,
= Time to known failure at known temperature K T, t, = Projected time to failure at new temperature
'K T~
R
= Universal gas constant (1.987 cal/mole 'K)
= Activation energy (50 kcal/mole)
As a result of these time projections, the licensee replaced the four Pressurizer vapor space nozzles during the next refueling outage, end of cycle (EOC)
3 in the fall of 1987.
Liquid penetrant examination from the I.D. prior to the removal of the nozzles indicated that two of the four nozzles were cracked, no leaks were identified.
The Pressurizer liquid space nozzle was visually examined at EOC 3 (no leaks identified)
and scheduled replacement at EOC 4 with the availability of needed technology.
The licensee replaced the one Pressurizer liquid space nozzle and the five RCS hot leg RTD nozzles during a subsequent refueling outage EOC 4 in the winter of 1989.
Remote visual examination, with a fiber optic device, of these five nozzles identified no cracks, no leaks were identified.
The basis for the delay in the replacement of the hot leg nozzles was their lower operating 'temperature (50 'F below the
, Pressurizer vapor space design temperature).
Because of the significantly lower operating temperature of the RCS cold leg (103
'F below the Pressurizer vapor space design temperature),
the time to failure t~
for the RCS cold leg RTD nozzles was projected to exceed the 40 year plant life, and therefore those nozzles were not replaced.
The reactor flange leak detection nozzles did not represent a
PWSCC concern and were not replaced because they are not normally wetted or pressurized and operate at temperature lower than the other nozzles.
The ten replaced Inconel Alloy 600 Heat No 54318 nozzles were replaced with Inconel Alloy 600 Heat No 41501.
On March 2, 1993, during the heat up of the RCS for restart, with the plant in Mode 5 at 200 psig and 100 'F, the licensee discovered slight leakage emanating from under the insolation on the Unit 2 Pressurizer.
Upon removal of the insulation on March 3, 1993, it was discovered that four of the four Pressurizer one inch vapor space nozzles replaced during the fall 1987 refueling outage with Inconel Alloy 600 Heat No. 41501, were leaking, none of the liquid
space nozzles were leaking.
The preliminary root cause was determined to be PWSCC caused by the residual stresses resulting from the installation welding applied to susceptible Inconel Alloy 600 material.
The licensee inspected all of the other Inconel Alloy 600 Heat No. 41501 nozzles and found no additional leaks.
There is no Inconel Alloy 600 Heat No. 41501 in Unit l.
The licensee contracted with ASEA Brown Boveri/Combustion Engineering Nuclear Power (CE) to conduct the repair effort under the umbrella of the CE guality Assurance (gA) program.
and Eddy Current (EC) examinations of the four vapor space Pressurizer nozzles conducted from the Pressurizer I.D.
revealed one to three axial cracks in the bore of each of the four nozzles extending from approximately the root of the nozzle installation welds at the I.D. surface of the nozzles, extending axially to Pressurizer I.D. surface end of the nozzles, and continuing radially across the nozzle ends into the nozzle installation welds.
CE removed by grinding the installation welds (E-NiCrFe-3)
on all four nozzles, and removed the nozzles from the Pressurizer.
A portion of some of the cracks remained in the nozzles after their removal.
Those nozzles were sent to the CE laboratories at Windsor CT, for metallurgical evaluation.
With the use of a template, the remaining nozzle installation weld metal was removed by grinding, leaving four cavities in the configuration of the original installation weld preparation.
The cavities were PT examined and the remaining portion of the original cracks were removed by grinding.
All of the cracks were removed within the Inconel weld metal butter layer (E-NiCrFe-3) verified by PT examination.
None of the cracks extended into the P-3 base material of the Pressurizer, however some of the removal excavation cavities extended to Inconel weld metal/P-3 base material interface.
The original construction code is the ASME B8PV Code Section III 1971 Edition with Addenda through Summer 1972 (71S72).
The applicable code for the pressurizer repair and nozzle installations is ASME BLPV Code Section XI 80W80 and Section III 1986 with no Addenda.
The CE recovery plan was to repair weld the cavities in the Inconel buttering layer in accordance with ASME B8PV Code Section III, Paragraph NB-4622. 11
"Temper Bead Weld Repair to Dissimilar Metal Welds or Buttering" to avoid the necessity of Post Weld Heat Treatment (PWHT) that would otherwise.
be required.
The buttering layer repair would be followed by the Inconel to Inconel nozzle installation weld for the replacement nozzles, which requires no PWHT.
The replacement nozzles are ASME SB-166 Inconel Alloy 690, vice Alloy 600, with the instrument nozzle safe-ends changed from ASME SA-182 F316 to ASME SA-182 F316L.
There is a large body of data that indicates that both material changes will improve significantly the corrosion resistance of the nozzle/safe-end assembly.
The lower stress allowable for the F316L material is above the calculated normal operating stress level in the nozzle Inspection The inspector interviewed licensee and contractor personnel, observed work activities, and reviewed the licensee's and contractor's program, procedures and records, as described below to determine whether the Pressurizer recovery effort was being accomplished consistent with procedural and regulatory requirements.
(1)
Work Activities Observed The inspector observed preparation and welding activities for the first attempt at the temper bead weld repair to Nozzles A, B, C,
and D buttering layer crack removal cavities.
With regard to the observation of work activities, the inspector noted the following:
(a)
The ASHE B&PV Code Section III, Paragraph NB-4622. 11(c)(6),
requires that the first layer of weld metal of a temper bead repair be deposited using a 3/32 inch diameter electrodes, that the weld bead crown be removed by grinding, and the second layer be deposited with an 1/8 inch diameter electrode.
Contrary to the above, during the temper bead repairs to all four nozzles'uttering layer, the second layer of weld metal was deposited with 3/32 inch diameter electrodes.
This is of concern because, the smaller electrode (3/32 vice 1/8 inch diameter)
provided less heat input to the weldment and thus less tempering effect on the brittle martinsitic microstructure that had developed in the base material under the first layer
, of weld metal.
This is an example of violation 50-389/93-08-01 discussed further in paragraph 2c.
(b)
Procedure CE-EP-9417-CSE-3102, Revision 0,
"Procedure for Replacement of a Pressurizer Upper Instrument Nozzle at Florida Power
& Light St.
Lucie Unit No. 2" and ASHE B&PV Code Section III, Paragraph NB-4622. 11(c)(5), require that the weld area, on a temper bead repair, plus a band around the weld for five inches be preheated to a minimum temperature of 350 F and a
maximum interpass temperature of 450 F during welding, monitored by thermocouples and recording instruments.
Contrary to the above the thermocouples were not placed in locations such that they would monitor temperatures at the periphery of a five inch band around the weld.
The thermocouples were actually placed at distances of lq to four inches from the welds.
CE Procedure CE-STD-100-89, Revision 6, "Set-Up Requirements for Heat Treating Equipment",
paragraph 4.8(3)
requires that two thermocouples be attached around the weld area at the 3:00, 6:00, 9:00, and 12:00 positions.
Two thermocouples, in point of fact, were placed at the 11:30 to 12:30 and 5:30 to 6:00 positions of each nozzle repair weld, therefore, they would not uniformly monitor the periphery of
the band around the repair weld.
This is of concern because the preheat temperature at the five inch periphery of the temper bead repair weld area was unknown.
This is an example of violation 50-389/93-08-01 discussed further in paragraph 2c.
(c)
The ASME B&PV Code Section III, Paragraphs NB-4622. 11(c)(5)
and NB-4435(b) require the immediate area around the temporarily attached thermocouples be marked so the removal area can be identified after their removal for subsequent Nondestructive Examination.
Contrary to the above, several of the temporarily attached thermocouples were inadvertently removed without the immediate area around those temporarily attached thermocouples, being first marked.
This is of concern because there is a
potential that the removal.location would not be properly examined.
This is an example of violation 50-389/93-08-01 discussed further in paragraph 2c.
(d)
An inadvertent arc strike near the top of the Pressurizer manway, was not reported for evaluation and repair until the next day when identified by the this inspector.
This is of concern because there is a strong likelihood that the arc strike would have remained unidentified and thus uncorrected.
Arc strikes have the potential of producing brittle microstructure and cracks in P-3 materials.
(2)
Program Documents and Procedures Examined ID Revision Title CE-SLRM-024 3/6/93 Probable Root Cause Technical Evaluation FPL-JPN-93-0200 3/9/93 Cracking of RCS Instrument Nozzles and Pressurizer Heater Sleeves REA SPSL-93-027-20 FPL-PC/M 096-287 9/9/87 Pressurizer Nozzle Replacement FPL-PC/M-36-293 (RO)
Pressurizer Upper Head Instrument Nozzle Replacement CE-EP-9417-CSE-3102 (RO)
Procedure for Replacement of a Pressurizer Upper Instrument Nozzle at Florida Power
& Light St. Lucie Unit No.
2 (Engineering Procedure)
Program Documents and Procedures Examined Cont'd
ID Revision
. Title CE-2001935-003 3/7/93 CE-EP-9417-CSE-3103 (R2)
Pressurizer Upper Instrument Nozzle(s)
Replacement of Top Head and Upper Level and Pressure Tap Nozzles (Traveler)
Procedure for Weld Repair of Dissimil ar Metal Welds/Weld Butter/Base Material By The
"Temper Bead" Welding Process Pressurizer Upper Nozzles at Florida Power
& Light-St. Lucie Unit 2 (Engineering Procedure)
CE-2001935-005 3/9/93 Weld Repair of Pressurizer Dissimilar Welds/Weld Butter/Base Material (Traveler)
CE-STD-100-89 (R6)
Set-Up-Requirements for Heat Treating Equipment CE-9392-OP-93-009 (RO)
CE-EP-9417-CSE93-3104 (R1)
guality Plan Procedure for Macroetching of Carbon Steel, Low Alloy Steel and Austenitic Weld Surfaces (Engineering Procedure)
CE-OP-9. 4 CE-OP-9.1 (R12)
(R7)
Liquid Penetrant Examination Visual Examination of Completed Weld Surfaces CE-WPS-SMA-3.43-919 (R5)
(Untitled)
CE-P(R-SMA-3.43-1188 12/13/89 (P(R supporting CE-WPS-SMA-3.43-919)
CE-WPS-SMA-43.43-909 (R2)
CE-PgR-SMA-43.43-102 3/5/73 CE-WPS-GTA-8.8-910 (R8)
(Untitled)
(PgR supporting CE-WPS-SMA-43.43-909)
(Untitled)
CE-PgR-GTA-8.8-100 11/10/72 (P(R supporting CE-WPS-GTA-8.8-910)
Program Documents and Procedures Examined Cont'd ID Revision Title CE-POR-GTA-8.8-104 1/20/82 (P(R supporting CE-WPS-GTA-8.8-910)
FPL-410-010 (RO)
Eddy Current Examination of Inconel 600 Nozzles With regard to following:
the review of documents and procedures, the inspector noted the (a)
(b)
The ASME BBPV Code Section III, Paragraph NB-4622. 11(c)(6),
requires that the first layer of weld metal of a temper bead repair be deposited using a 3/32 inch diameter electrodes, that the weld bead crown be removed by grinding,. and the second layer be deposited with using 1/8 inch diameter electrode.
CE Engineering Procedure EP-9417-CSE-3103; revision 2, "Procedure for weld repair of Dissimilar Metal Welds/Weld Butter/Base Material By The
"Temper Bead" Welding Process Pressurizer Upper Nozzles at Florida Power 8 Light-St. Lucie Unit 2, CE traveler 2001935-005, dated 3/9/93,
"Weld Repair of Pressurizer Dissimilar Welds/Weld Butter/Base Material",
and CE-WPS-SMA-
.
3.43-919, Revision 5, all specify that the first layer of weld metal of a temper bead repair be deposited using a 3/32 inch diameter electrodes, that the weld bead crown be removed by grinding, and the second layer be deposited with an 1/8 inch diameter electrode maximum.
The word maximum used above infers, contrary to ASME Code paragraph NB-4622. 11(c)(6), that electrodes of diameters smaller than 1/8 inch could be used for depositing the second layer of the temper bead repair.
This discrepancy went undetected by the CE authors and all the reviewers at CE as well as all the FPL reviewers including the St. Lucie Facility Review Group (FRG).
This discrepancy was identified by this inspector on March 14, 1993, after the completion of the first attempt at the temper bead repair to al-l four nozzles.
This oversight resulted in 'the improper use of 3/32 inch diameter electrodes in the deposition of the second layer of the temper bead repair as discussed above.
This is an example of violation 50-389/93-,08-01 discussed further in paragraph 2c.
ASME B&PV Code Section III, Paragraph NB-4622. 11(c)(5),
requires that the weld area, on a temper bead repair, plus a
band around the weld for five inches be preheated to a minimum temperature of 350 'F and a maximum interpass temperature of 450 F during welding, monitored by thermocouples and recording instruments.
CE procedure STD-100-89, Revision 6,
"Set-Up Requirements for Heat Treating Equipment",
paragraph 4.8(3)
specifies that thermocouples shall not exceed a distance of
four inches from the edge of the weld.
Although CE Engineering Procedure EP-9417-CSE-310, Revision 2, and CE Traveler 2001935-005, dated 3/9/93, did address the ASME B&PV Code Section III, Paragraph NB-4622. 11(c)(5) five inch requirement, CE-STD-100-89 is the working procedure for the installation of the thermocouples.
This'discrepancy between the Code, Engineering Procedure, and Traveler on the one hand, and CE-STD-100-89 on the other, went undetected by the CE authors and all the reviewers at CE as well as all the FPL reviewers as discussed above.
This discrepancy was identified by this inspector on March 14, 1993, after the completion of the first attempt at the temper bead repair to all four nozzles.
There is a strong likelihood that the incorrect incorporation of the five inch weld to thermocouple requirement in CE-STD-100-89 is the cause of the improper location of the thermocouples discussed above.
This is an example of violation 50-389/93-08-01 discussed further in paragraph 2c.
The ASME B&PV Code Section III, Paragraphs NB-4622. 11(c)(5)
and NB-4435(b) requirement that the immediate area around the temporarily attached thermocouples be marked so the area can be identified after their removal for subsequent Nondestructive Examination, was not incorporated into any procedures provided by CE.
The lack of the incorporation, into the CE site procedures, of the marking requirements for temporary attachments, went undetected by the CE authors and all the reviewers at CE as well as all the FPL reviewers discussed above.
This discrepancy was identified by this inspector on March 14, 1993, after the completion of the first attempt at the temper bead repair to all four nozzles.
There is a strong likelihood that the lack of the incorporation into the CE site procedures, resulted in the thermocouple areas not being marked prior to removal as discussed above.
This is an example of violation 50-389/93-08-01 discussed further in paragraph 2c.
Records Examined The inspector examined Nonconformance Reports, welder qualification and qualification maintenance records, welding filler material receiving inspection and certification documentation, NDE material certification.documentation, and NOE examiner qualification, certification and visual acuity records listed below.
Nonconformance Reports Reviewed CE-2001935-1 CE-2001935-2 CE-2001935-3 CE-2001935-4
Welder Records Examined DKD-4241 DCD-4607 WJL-1536 SFS-1209 JAB-9201 JSE-2685 JNG-6230 JRH-1846 JEL-8774 RL-1032 Welding Filler Naterial Records Examined E-NiCrFe-3 E-NiCrFe-3 ER 316L 3/32" HT 53A7 1/8" HT 57A3 1/16" HT S34503 NDE Records Naterial Examined Penetrant 91H02K and 90L02K Cleaner 92GOlP and 92H02P Developer 91H05K and 93A01P NDE Examiner Records Examined c ~
SEC PT-II and VT-II BHN PT-II and VT-II RT PT-II and VT-II In addition the inspector examined the weld inspection records for the first attempt temper bead welding of Nozzles A, B, C,
and D,
and various Tool/Haterial Accountability Logs.
Conclusion The issues discussed in Paragraph Nos 2b(1)
and 2b(2) demonstrate multiple failures relating to the control of contractors and related activities; review and approval of contractor progress at the site; understanding of the ASHE B&PV Code requirements by the NSSS organization and by FPL Welding Engineers, NDE Engineers, Codes and Standards Sections, and guality organizations.
These issues also demonstrate multiple failures to accomplish the welding in accordance with the ASHE B&PV Code, and are indicative of inadequate measures to control special processes including welding, which is a
violation 10 CFR 50, Appendix B, Criterion IX. This violation will be identified as 50-389/93-08-01:
Failure To Provide Adequate Measures to Control Welding.
In the areas inspected, no violations or deviations were identified except as noted in paragraph Nos 2b(l), 2b(2),
and 2c.
4.
Exit Interview The inspection scope and results were summarized on March 17, 1993, with those persons indicated in paragraph 1.
The inspector described the
areas inspected and the findings listed below.
Although reviewed during this inspection, proprietary information is not contained in this report.
Dissenting comments were not received from the licensee.
(Open) Violation 50-335,389/93-08-01:
Failure To Provide Adequate measures to Control Welding.
5.
Acronyms and Initialisms ASHE BLPV CE CFR DPR EC EOC FPL GTA ID I.D.
NDE No.
NPF NRC NSSS O.D.
P.E.
PQR Psig.
RCS RTD SCE SHA SONGS UT WPS American Society of Hechanical Engineers Boiler and Pressure Vessel ASEA Brown Boveri/Combustion Engineering Code of Federal Regulations
.Demonstration Power Reactor Eddy Current End of Cycle Florida Power 5 Light Gas Tungsten Arc (Welding)
Identification Inside Diameter Nondestructive Examination Number Nuclear Power Facility Nuclear Regulatory Commission Nuclear Steam System Supplier Outside Diameter Professional Engineer Procedure Qualification Record Pounds Per Square Inch Gauge Liquid Penetrant Primary Water Stress Corrosion Cracking Quality Assurance Revision Reactor Coolant System Resistance Temperature Detector Southern California Edison Shielded Hetal Arc (Welding)
San Onofre Nuclear Generating Station Ultrasonic Melding Procedure Specification