IR 05000282/1992020
| ML20126L640 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 12/31/1992 |
| From: | Jeffrey Jacobson, Ward K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20126L620 | List: |
| References | |
| 50-282-92-20, 50-306-92-20, NUDOCS 9301080080 | |
| Download: ML20126L640 (9) | |
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U.
S. NUCLEAR REGULATORY COMMISSION
REGION III
Reports No.- 50-282/92020(DRS);
Licenses Not DPR-42; 50-306/92020(DRS)
Licenses No:- DPR-60 Docket Nos. 50-282; 50-306 Licensee Northern States Power Company 414 Nicollet Hall Minneapolis, MN 55401 Facility Name:
Prairie Island Nuclear Generating Station Units 1 and 2 Inspection At:
Prairie Island Site, Red Wing, MN Inspection Conducted:
September 28 through December 23, 1992 M[ kjl
/,L/7@Y,.L.
Inspector:
K.
D. Ward Date IL/31h Approved By: '
la J, M. Jacobs'on, Chief Date Materials and Processes Section Insnection Summary Insoection on Seotember 28-Octcber 1.
-November 16-18, 23-25.
December 16-18.
and December 22-23.
1992 (Recorts No.
50-282/92020(DRS); 50-306/92020(DhS)).
Areas Insoected:
Routine, unannounced safety inspection of inservice inspection _ (ISI) activities, including review of programs (73051), data (73755), procedures (73052), observations of_ work activities (73753), review of the erosion / corrosion- (E/C) program -
(49001), facility modifications ' (37701), - and licensee - action on previous. inspection findings (92700, 92701).
Ensults:
No violations or deviations Were identified.
Based cn1 the -results of the inspection, the - NRC inspector noted the following:
o The implementation:of the ISI, E/C and modifications complied with the requirements of the applicable Codes and the licensee's program, o
Licensee staff and contract personnel lavolved in the ISI, E/C and' modifications were knowledgeable and' competent.
o In general, the inspection results indicate centinuing good performance in the areas of ISI, E/C and modifications.
o The licensee's actions in resolving the previous inspection
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findings were found to be acceptable.
9301080080 921231-PDR ADOCK 05000282'
G PDR
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DETATIA 1.
Persons Contacted Hprthern States Power Company (NSP)
- H.
Sellman, Plant Manager
- K. Albrecht, General Superintendent, Engineering
- G.
Miller, Superintendent, Technical support
- R.
Fraser, Superintendent, Mechanical
- J. Mcdonald, Superintendent, Site QA
- J.
Bridgman, Senior Materials and Special Processes Engineer
- T. Jones, Materials and Special Processes
- M.
Vik, Materials and Special Processes
- L.
Ganser, QA Specialist U.
S.
Nuclear Reculatory Commission (NRC)
- M.
Dapas, Senior Resident Inspector D.
Kosloff, Resident Inspector Lambert. MacGill. Thomas, Inc. (LMT)
D. MacGill, Level III (Vice President)
Conam Nuclear. Inc. (Conami R. Marlow, Level III Zetec. Inc. (Zetec)
R. Vollmer, Level III Hartford Steam Boiler Inspection and Insurance Company (HSB)
L.
Dillon, ANII The NRC inspector also contacted and interviewed other licensee and contractor employees.
- Denotes those present at the exit interview on December 23, 1992.
2.
Innervice Insnection - Units 1 and 4 a.
Procram Review (73051)
Personnel from LMT, Conam Nuclear, Inc., and Zetec, Inc.,
performed the ISI ir 3ccordance with ASME Section XI, 1980 Edition, Winter.t '1 Addenda.
The licensee did not
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request relief from ':%
>SME Code for this outage. Audit
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No.
AG 92-38 and
- a, sillances of the ISI program v
activities performed by Northern States Power (NSP) were i
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I reviewed and found to be acceptable and performed by qualified personnel. Organizational staf fing for the ISI program was found to be acceptable and the services of an Authorized Nuclear Inservice Inspector (ANII)
were procured from the Hartford Steam Boiler Inspection and Insurance Company.
The qualifications and certifications of all inspection personnel performing ISI were reviewed to ensure conformance with SNT-TC-1A.
b.
Ergsedure Review (73052L All applicable ISI procedures were approved by the ANII.
The ISI procedures were found to be acceptable and in accordance with ASME Section V,1980 Edition, Winter 1981 Addenda, c.
Data Review (73755)
(1)
General The examination data was found to be in accordance with the applicable ISI procedures and ASME Code requirements.
The NRC inspector reviewed documents related to nondestructive examinations, equipment, data, and evaluations.
(2)
Eddy Current Examination (ET) Unit 1 The primary to secondary leak rate in steam generator No. 12 was 0.1 gpm prior to the Unit 1 shutdown September 24, 1992.
Three tubes were identified with through wall leakage.
The major source of-this leakage was tube No. R13C43 that had a 11" long axial indication in tho tube above the roll transition region.
Two additional tubes, No.
R15C40 and No. R2C49 were found to be leaking after steam generator No. 12 had been pressurized to 700 psig for two days.
Both of these tubes had short multiple axial indications in the roll transition.
Prior to startu'p, 100% of all accessible tubes in steam generator No.12 were examined from the first support plate through the tube end.
There were 27 unacceptable tubes with all the indications located in the hot leg tube sheet crevice area.
All 27 tubes were pluaged.
The following was the steam generator No.
plugging and sleeving summary prior to start up.
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New Indications' Plugged This Outage
New Indications Sleeved This Outage:
0-Total Tubes Plugged:
Total Tubes Sleeved:
162 Approximately one month later, Units-1 and 2-
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shutdown and during this outage 100%
of all accessible tubes in steam generator No.
12_ were -
examined full length again.
Also in steam generator No. 11, 100% of all accessible tubes were examined.
The examinations were conducted utilizing the Zetec MIZ-18 multifrequency_ digital examination equipment with associated acquisition software and remote positioning devices.
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Motorized rotating pancake coil (MRPC) examinations were performed in addition to the bobbin _ coil examinations.
Approximately 20% of the - tubes in steam generator No.11 were examined using the MRPC in the tube sheet crevice region.
The MRPC examinations were performed on-100%
of all-accessible tubes in steam generator No. 32.
Conam was contracted to acquire _and evaluate the eddy current data.
Zetec was contracted to perform a completely independent evaluation of all data acquired by Conam.
Zetec utilized computer data screening of all bobbin coil data.
The following-tubes were plugged and_ sleeved as a result of this examination:
Steam Generator No. 11 New Indications Plugged This Outage:
New Indications Sleeved This Outage:
Total Tubes Plugged:
Total Tubes' Sleeved:
O Steam Generator No. 12 New Indications Plugged This Outage:
_ 21 New Indications Sleeved This Outage:
_158 Total Tubes Plugged:
120-Total Tubes Sleeved:
319 All of the new steam generator tube plugs were Inconel 690 - alloy.
Also five Inconel 600 - alloy _
plugs were removed in response to NRC Bulletin-89-01, replacing them with Inconel 690 alloy.
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Observations of Work Activities (73753)-
.The NRC inspector obsewed the following work activities and had discussions with personnel during the ISI activities.
(1)
Conam personnel performing eddy current examinations. on the tubes in the two steam generators and Conam and Zetec personnel evaluating eddy current examination data on Unit 1.
(2)
IRT personnel performing ultrasonic examinations using the master / slave video-system on pipe-~ weld No. FW-94, and of the steam generators feed nozzle interadious welds No.-N1IR-11 and No.
These three welds were on Unit 1.
Also observed ultrasonic examinations using the master / slave on the steam generators feed nozzle interadious welds No. N11R-12 and No. N11R-22.
These welds were on Unit 2.
No violations or deviations were identified.
3.
Erosion / Corrosion (E/C) Activities. Units 1 and 2 (49001)
Northern States Power Company (NSP) began their program in 1979.
In 1985, a formalized procedure and administrative controls were developed to ensure. continued long-term implementation of an E/C monitoring program for piping and components (Reference NRC Inspection Report No. 50-3 % /92002 (DRS)).
For this refueling outage, NSP selected an inspection sample of approximately 216 components for Unit 1 and approximately 39 components for Unit 2, utilizing the NSP computer program.
Of the components examined, one small-length of small bore heater drain piping was unacceptable and replaced this outage.
The NRC inspector reviewed the E/C program,-_ procedures, NDE
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certifications, data from previous inspections, and observed LMT personnel perf arming ultrasonic thickness examinations of several piping components on the high pressure bleed steam system.
To date, several components and pipe sections have been repaired / replaced as a result of the E/C-. program.
The NRC inspector observed the Welding Services, Inc. (WSI) personnel nerforming cutting, fitting, and welding operations,- and
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visually examined completed repairs on the high pressure bleed l-system.
The NRC inspector also reviewed work requests, drawings, weld data sheets and other related documentation.
No violations or deviations were identified.
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4.
Modifications (37701) Units 1 and 2 The NRC inspector reviewed plant modifications in progress riuring the current outage.
The designs of the following uodifications were in accordance with USAS B31.1-1967, and the required inspections were in accordance with ASME Section XI.
a.
Coolina Water Pinina. Loons "A" and "B" Modifications No.
92Y170.
A number of indications of wall thinning were identified in the cooling water system.
There was a discussion to replace the main header cooling water piping from the outlet of the cooling water strainers (1d") through and incluaing motor operated valves No.
MV32144 and No.
MV3215, that experienced microbiological induced corrosion and resultant pipe wall loss.
The new header piping was the same piping material, a 106 grade B,
having a 1/2" vall thickness instead of 3/8" wall thickness that existed in the old pipe.
Those portions
- o of the cooling water headers embedded in concrete and a portion of the buried piping were replaced and had weld overlay in localized degraded areas.
The repaired areas and the new pipe had a protective coating applied as an economic means to prolong the pipe life.
Additional valves were added to permit localized system isolation to enhancc maintenance.
The NRC inspector observed the Welding Services, Inc.
(WSI) and NSP personnel cutting, fitting, and welding operations, and visually examined several completed welds.
The NRC inspector also reviewed the welding manual, drawings, weld data sheets, and other related documentation.
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No violations or deviations were identified.
b.
Reactor Coolina System (RCS) Drain Down Modifications No.
22L362.
During the February 1992, Unit 2 refueling outage, NSP violated 10 CFR 50, Appendix B.
Procedure D2,
"RCS Reduced Inventory Operation," Revision 21, for draining the RCS did not provide adequate instruction for completing the draining process.
The residual heat removal (RHR) cooling flow was interrupted for a period of time due to overdraining of the RCS.
In response to this event, NSP identified the following plant modifications that would enhance RCS reduced inventory operations and tuo drain down process.
(1)
Hot Lea Drain Line
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This modification modified-the RCS piping to provida an RCS hot leg drain path.
This piping was-routed to limit the RCS level during drain down to just below-the top inside diameter of the RCS hot leg piping.
A vent pipe and valve was_ installed _to prevent any' siphoning effects.
This configuration-was designed to provide protection against loss of RHR flow due to over draining of the RCS,, loss of RHR flow due to failure'of the RHR heat exchanger outlet flow control valve and provide for mitigation of loss of RHR accidents.
(2)
Purification Lina This modification modified the auxiliary-pressurizer spray (AUX PRZ SPRY)
line and the reactor coolant drain tank (RCDT) collection line to provide a shut down purification path from the RCS.
Double isolation valves were installed in the purification line to provide positive isolation during normal operations.
A sectional isolation valve was installed in_the spray line to isolate the Loop B spray scoop and the pressurizer from the new purification path.
The purifi. cation path -is from the Loop A PRZ ' SPRY sccop through the spray line, auxiliary spray line, new purification cross tie line and then via the RCDT collection line to
'the RCDT.
From this point on the shut down purification process'was unchanged.
(3)
Looo A Communications Line This modification modified the RTD. piping to provide a shut down communication path between the Loop A hot and cold leg RTD piping.
The new piping-connecting the hot and cold leg RTD piping vent included a new isolation valve.
During : normal operations the' existing vent valve on the cold leg vent and the new isolation valve are to be closed to provide positive isolation between the hot and
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Between these two isolation valves a common vent was provided.
This vent was constructed with a
swaglok fitting-consistent with existing RCS vents.
The -Loop B '
configuration already provides a communication path via the-pressurizer.
(4)
Reactor Coolant Gas Vent (RCGV)
System Orifice Bvoass This modification modified the RCGV piping adjacent to the reactor. vessel - head _ to provide a bypass
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h around !- the RCGV - flow restric61on orifice.' --
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modification was required to assure more' timely __
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pressure equalization-of the reactor head volume i'
with the RCS loop-volumet during the. draining
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process.-
The'RCGV piping ~ was reEovedi from. just?
below the :tsolation valve on the - reactor - head through the first flange connection on ; theiJpoolo piece.
The piping and a'
valve : assembly :were-fabricated to provide a-bypass around'the' orifice
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including a 3/4" isolation valve which shall-- be a
shut during normal operations.
The NRC inspector observed the WSI and -NSP personnel
cutting, fitting, and welding operations, and visually examined several completed welds. The NRC inspector also -
reviewed procedures, drawings, weld-data sheets, and'
other related documentation.
No violations or_ deviations were-identified.
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c.
Feedwater Ploe Modification No. 92Yl85 This modification replaced the transition section of the
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steam generator to feedwater piping-which was susceptible'_-
to damage from thermal fatigue._ The replacement transi
tion-section has a greater-cross sectionJthus reducing the stresses.;
The modification _was - accomplished _ by'
cutting back on.the steam generator inlet nozzles toa
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location where the wall thickness was 1-1/31". ALforging-insert was designed'to match the diameter and the wall thickness and-was welded in place at this. location.~ The-purpose of the modification was -to ; reduce - all-piping -
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stresses acting on this region of the_ system, especially.
the high stresses-resulting fromthe ' hot standbyJ condition.
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The NRC" inspector observedua forgi'ng insert 4it place in the steam generator inlet nozzle prior _ to welding?and -
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visually examined the_ entire area.'
The-NRC inspectorJ also reviewed procedures,' drawings, _ weld' data sheets,5 and:
other related documentation.
No violation or deviations-were identified.-
-j 5.
Licensee Action on a Previous Insoection Findina
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-(Closed) Followup Item -(30-282/92015 03 ; 50-306/92-15-03 (DRP)I (72701).
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(Closed LER No. 011-(72700).
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The licensee identified longitudinal -. weld: examinations not-performed in the' low pressure safety. injection (SI)', residual.
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heat removal (RilR), and the main steam (MS) systems.
All the ISI summary reports were reviewed by the licensee for examinations performed from the SI, RllR, and MS drawings.
It was found that the carbon steel (C/S) long scam piping and components were in the 30" and 31" diameter MS system.
Stainless steel (S/S) long scam piping and components were found in the SI and Rl!R low pressure systems.
A total of 8 examinations in Unit 1 and 7 examinations in Unit 2 were performed on the C/S long seam piping and components and 22 examinations in Unit 1 and 28 examinations in Unit 2 were performed on the S/S long seam piping and components.
All the C/S and S/S long seam piping and components examined were found to be acceptable.
The NRC inspector revievad the " Justification for Continued Operation" (JCO),
drawings, NDE reports, other related documentation and considers this followup /LER item closed.
6.
Exit _Intprview The NRC inspector met with licensee representatives (denoted in Paragraph 1)
at the conclusion of the inspection and summarized the scope and findings-of theeinspection noted in this report.
The NRC inspector also discussed the likely informational content of the inspection report with regard to documents or processes refiewed by the inspector during the inspection.
The licensee did not identify any such documents / processes as proprietary.
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