ML20151T165
| ML20151T165 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 08/08/1988 |
| From: | Kingsley O SYSTEM ENERGY RESOURCES, INC. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| GL-88-01, GL-88-1, NUDOCS 8808160277 | |
| Download: ML20151T165 (27) | |
Text
J' EYb7EM ENERGY REEOGRCEE, INC.
OLfvin D KtrAR JR vce neso.vt rum ca e"*
August 8,1988 U. S. Nuclear Regulatory Commission Mail Station P1-137 Washington, D. C.
20555 Attention: Document Control Desk Gentlemen:
SUBJECT:
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Generic Letter 88-01 AECM-88/0153 This submittal provides System Energy Resources, Inc. (SERI) response to the NRC Position On Intergranular Stress Corrosion Cracking In Boiling Water Reactor Austenitic Stainless Steel Piping (Generic Letter 88-01) letter dated January 25, 1988.
In a telephone conversation on Augus. 2,1988 the Grand Gulf Nuclear Station Project Manager, L. L. Kintner, agreed to an extension of the submittal date of the attached report to August 8, 1988.
In accordance with 10CFR50.54(f) SERI is providing the required a ffirmation.
If additional infonnation is required, please contact this office.
You
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'cc:-:Mr. T. H. Cloninger (w/a)
Mr.H.L. Thomas (w/o)
Mr. R. B. McGehee-(w/a)
Mr. R. C. Butcher (w/a) 4 Mr. N. S. Reynolds (w/a)
- Dr. 'J. Nelson Grace, Regional Administrator (w/a)
U. S. Nuclear Regulatory Commission Region II-
)
101 Marietta St., N. ii., Suite 2900
-Atlanta, Georgia.30323 Mr. L. L. Kintner, Project Manager (w/a)
Office of Nuclear Reactor Regulation U..S. Nuclear Regulatory Commission Mail Stop 14B20 Washington, D.C.
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BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION LICENSE NO. NPF-29 D0CKET N0. 50-416 IN THE MATTER OF MISSISSIPPI POWER & LIGHT COMPANY and SYSTEM ENERGY RESOURCES, INC.
and SOUTH MISSISSIPPI ELECTRIC POWER ASSOCIATION AFFIRMATION I, 0. D. Kingsley, Jr., being duly sworn, state that I am Vice President, f;uclear Operations of System Energy Resources, Inc.; that on behalf of System Energy Resources, Inc., and South Mississippi Electric Power Association I am authorized by System Energy Resources, Inc. to sign and file with the Nuclear Regulatory Comission, this response to Generic Letter 88-01 that I signed this application ac Vice. President, Nuclear Operations of System Energy Resources, Inc.; and that the statements made and the matters set forth therein are true and correct to the best of my knowledge, nformation and
. belief.
L STATE OF MISSISSIPPI COUNTY OF HINDS SUBSCRIBED AND SWORN T0 bef me, a N ary Public, in and for the County and State above named, this day of ad
, 1988.
(SEAL) n0w i
Notary Public My comission expires:
uj twsn 6; u &;L 27,1sn
' J14AECM88072601 - 3 k
b GRAND GULF NUCLEAR STATION UNIT 1 RESPONSE TO GENERIC LETTER 88-01 I
NRC POSITION ON IGSCC IN BWR AUSTENITIC STAINLESS STEEL PIPING PREPARED BY NUCLEAR PLANT ENGINEERING F. W. TITUS, DIRECTOR l
I APPROVED BY
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C RES10Ef4T, NIJC AR Et ERING and S POR l
Response To Generic Letter 88-01
~.
NRC Position On IGSCC In 34R Austenitic Stainless Steel Piping a
TABLE OF CONIDTIS b
4
- I.
DTCUI'IVE SUM 4ARY................................................... 1 I.
INIRODUCI' ION........................................................ 4
~
II.
GDIERIC IEITER 8 8-01. ITD4 1........................................ 8 III.
GDIERIC IEITER 88-01. ITEM 2....................................... 11
[
IV.
GDfERIC IEITER 88-01. ITD4 3....................................... 14 V.
QDJERIC 1EITER 88-01. ITEM 4....................................... 15 VI.
,GDIERIC IEITER 8 8-01. ITD4 5....................................... 2 0 i
f 4
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Response To Generic.Istter 88-01 NRC Position On IGSCC In ENR Austenitic Stainless Steel Piping Page 1 of 22 l
i EXECUTIVE
SUMMARY
Generic Intter 88-01 has requested licensees of BWR facilities to evaluate plant systems to criteria published in NURE 0313, Revision 2 to determine what actions are required to ensure long-tem piping integrity and reliability against intergranular stress corrosion cracking (IGSCC).
GGtG has evaluated systems cxmprising the reactor coolant pressure boundary and has identified 268 welds that required classification into the seven IGSCC Categories.
Results of the classification cre shown below:
Category A 210 welds Category B 24 welda Category C 0 welds Category D 34 welds l
Categories E, F, and G 0 welds The Category "A" welds are fabricated frun materials that are determinod to be IGSCC resistant and require examinations similar to ASME Section XI utilizing IGSOC qualified personnel.
Le Category "B" welds are fabricated frun l
l l
Response 'Ib Generic letter 88-01 NRC Position On IGSOC In IMR Austenitic Stainless Steel Piping Page 2 of 22 j
nonresistant materials, but have received stress improvement within the first two years of operation and require examinations at an accelerated schedule using IGSCC qualified personnel.
'Ibe Category "D" Welds are fabricated from nonresistant materials and have not received stress improvement. 'Ihese welds require examination every alternate refuel outage and may be upgraded to Category "C" with the performance of stress inprovement.
Previous examinations c3nducted for empliance to NUREG 0313, Revision 1 and Generic Intter 84-11 have not identified any flaws representing IGSCC.
Currently, GGNS has no plans for the implementation of a pipe replacement program or the installation of a HydrorJ1 Water Chemistry system.
Personnel performing examinations under the scope of Generic Letter 88-01 will be qualified in accordance with the NDE Coordination Plan or other NRC approved l
programs for the detection or sizing of IGSCC.
'Ihe Inservice Insgection Pragam, Specification M-489.1, will be revised to incortnrate the requirements of Generic IRtter 88-01 as _ described within this report.
In addition, it is proposed that the Inservice Inspection Program be revised to recognize explian with Generic Istter 88-01 in lieu of adding inspection requirunents to the GGG 'Ibchnical Specifications.
1 i
'Ihe GGNS 'Nehnical Specifications have been evaluated and are in ccr:plianca with the NRC Staff Positions on Isakage Detection.
In the event GGG identifies IGSOC flaws excocding the acceptance criteria of f
ASME Section XI, IWB-3500, the NRC will be notified as required by Generic Intter 88-01.
If continued operation is permissible based on evaluations l
l l
l
F-b Response 'Ib Generic letter 88-01 NRC Ibsition On IGSCC In BE Austenitic Stainless Steel Piping j
Page 3 of 22 l_
performed in accordance with ASME Section XI, IWB-3640 and NUREG 0313 or repairs made in aamrdance with IWA-4130, NRC approval will be obtained prior i
to resLTption of operation.
Weld overlay repair designs would be performed in
.i accordance with ASME Section XI, IWB-3640 and NUREG 0313.
i s
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5 Response 'Ib Generic Istter 88-01 NRC Position On IGSCC In N R Austenitic Stainless Steel Piping l
Page 4 of 22 i
j' I.
INIHOEUCI' ION t
On February 02, 1988, System Energy Resources Inc. (SERI) received Generic letter 88-01, NRC Staff Position On IGSCC in NR Austenitic Stainless Steel Piping.
'Ihe issue of IGSCC has been addressed by SERI (MP&L) on two previous wxions; letter dated, 8/17/83 (AECM-83/0481) provided response to IUREG 0313, Revision 1, and letter dated, 6/3/84 (AECM-84/0297) provided response to Generic letter 84-11.
Generic Letter 88-01 provides the Nuclear Regulatory Comission's (NRC) long range plans to deal with BWR pipe cracking by the issuance of IUREG 0313, Revision 2 and also supersedes Generic Istter 84-11.
As such, the response l
contained in this suhaittal supersedes previous responses contained in AECM's 83/0481 and 84/0297.
As stated, Generic Intter 88-01 applies to all BWR piping made of austenitic stainless steel that is four inches or larger in ncminal diameter and contains reactor coolant at a temperature above 200 F during power operation regardless of Code classification.
It also applies to reactor vessel attachments and appurtenances such as jet prp instrumentation penetration assemblies and head spray and vent ocuponents.
'Ihe Generic Letter does not apply to piping rade of carbon steel classified as P-1 by the ASME Boiler and Pressure Vessel Cbde.
'Ib establish the scope of Generic Intter 88-01 as applicable to the Grand Gulf Nuclear Station (GGNS), the determination was made that piping containing reactor coolant is considered within the beurxlaries of the tractor coolant system. GGNS Unit 1 Updated Fimi Safety Analysis Report npe/ msg 88-01 rep
4 Response Ib Generic Istter 88-01 NRC Position On IGSCC In IMR Austenitic Stainless Steel Piping Page 5 of 22 I
(UFSAR), Chapter 5 defines the reactor coolant system as "...those systems and c.wr, rents which contain or transport fluids cxrting firm, or f
going to the reactor core."
PaIagraph 5.1.2 of the GGNS UFSAR lists the Piping and Instrument Diagrams (P&ID) covering the systems included within the reactor coolant system and its connected systems.
Those systems include:
o 7he Nuclear Boiler o Main Steam o Feedwater o Reactor Recirculation o Reactor Core Isolation Cooling o Residual Heat Rem:nal I
o Reactor Water Cleanup o Hign Pressure Core Spray o Iow Pressure Core Spray In addition,10CFR50.2 states " For nuclear power reactors of the direct I
cycle boiling water type, the reactor coolant system extends to and ircludes the outemost containment isolation valve in the mainsteam and feedwater piping."
The above reference is considered part of the following definition of the reactor coolant pressure boundary:
The reactor coolant pressure boundary (RCPB) includes all pressure j
containing ccrponents such as pressure vessels, piping, purps and valves which are:
npe/ msg 88-01 rep
t I
l:
Response Tb Generic Letter 88-01' NRC Position On IGSCC In BWR Austenitic Stainless Steel Piping Page 6 of 22 1)
Part of the reactor coolant r(stem or, i
2)
Connected to the reactor ecolant system, up to and including any and all of the following:
f a) The outermost containment isolation valve in piping strich penetrates primary reactor containment, b) the second of two valves normally closed during Icreal reactor operation in system piping which does not penetrate primary reactor mntainment, c) the reactor coolant system safety and relief valves.
l Based on the noted UFSAR and 10CFR50.2 definitions, it is determined that the scope of Generic Letter 88-01 is applicable to those portions of the 1
l GGNS systenu that serve as part of the RCPB and tint satisfy the criteria contained in Attachment A of Generic Letter 88-01.
Generic Intter 88-01 indicates that an acceptable res1x>nse frcan licensees woWd include the follcWing specific items:
{
- 1. Current plans regarding pipe replacement and/or other measures taken or to be taken to mitigate IGSCC and provide assurance of contint'sd long-tem piping integrity ard reliability, i
- 2. An Inservice Inspection (ISI) Program to be inplemented at the next l
refueling cutage for austenitic stainless piping covered under the scope of Generic Letter 88-01 that conforms to the staff positions on inspection rchedules, methods and personnel, and sample expansion l
l npe/ msg 88-Olrep I
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I, Response 'Ib Generic Istter 88-01 NRC Position On IGSCC In IMR Austenitic Stainless Steel Piping l
Page 7 of 22 1
included in Generic Istter 88-01.
- 3. A change to the 'Itchnical Specifications to include a statement in the section on ISI that the Inservice Inspection program for piping l
covered by the scope of Generic Istter 88-01 will be in confornance with the staff positions on schedules, methods and personnel, and sanple expansion included in Generic Intter 88-01.
It is recognized that the Inservi Inspection and Testing sections may be removed from the 'Ibchnical Specifications in the future in line with the Technical Specification Inprovement Programs.
In this case, this requirenent shall remain with the ISI section when it is includM in an alte1 native document.
- 4. Confinnation of your plans to ensure that the Technical Specification I
related to leakage detection will be in conformnce with the staff 4
position of leak detection included in Generic Istter 88-01.
- 5. In accordance with 10CFR50.55a(o), licensees plans to notify the IRC
+
of any flaws identified that do not meet IWB-3500 criteria of Section l
XI of the code for continued operation without evaluation, or a change found in the cordition of the welds previously known to be cracked, and the licensees evaluation of the flaws for continuM operation and/or the licensees repair plans.
'Ihe purpose of this report is to provide a status of current activities
,I and future actions to be taken at GGNS with respect to IGSCC and cmpliance with Generic letter 88-01.
'Ihis report provides a response to npe/mog 88-01 rep i
/
i Response 'Ib Generic Letter 88-01 NRC Fosition On IGSCC In IMR Austenitic Stainless Steel Piping I
Page 8 of 22 I
each of the five items requested by Generic letter 88-01.
'Ihe information contained within this report is based on SERI's understanding and inplementation of the thirteen Staff Positions provided by the Generic letter.
II.
GliERIC IEITER 88-01, ITEN 1 Ycur current plans regartling pipe replacement and/or other measures taken or to be taken to mitigate IGSCC and provide assurance of continued long-tern piping integrity and reliability.
SERI's RESPOtGE:
I As a result of SERI's review of the GGG systems using the criteria discussed in the previous section, the following systens and caponent connections contain weldments that are classified into one of the seven categories identified in Table 1 of Attachment A to Generic Letter 88-01:
o Reactor Recirculation System o Reactor Recirculation to Reactor Water Cleanup System connections o Reactor Recirculation to Residual Heat Removal System connections o Reactor Pressure Vessel Nozzle connections to safe enis and safe end I!
connections to safe en1 extensions / pressure seals
'Ihe material and fabrication records for weldments and associated base materials located in the systems listcd above were evaluated for empliance with the apprcpriate staff positions.
A total of 268 welds npo/ msg 88-01 rep
Response Tb Generic letter 88-01 f
NRC Position On IGSCC In DWR Austenitic Stainless Steel Piping Page 9 of 22 have been identified that are within the seven categories given in Attachment A, Table 1, to Generic Istter 88-01.
These welds have bcen categorized as shown below:
Category A 210 welds Category B 24 welds Category C 0 mlds Category D 34 welds i
Category E O welds Category F 0 welds Category G 0 welds Catectory A Welds Category "A" welds are weldments that are within the scope of Generic Istter 88-01 but have net the criteria of the staff positions and determined to be fabricated of "resistant materials".
Included in the GGNS Category "A" population are welds containing corrosion resistant cladding (CRC) and welds that have been solution heat treated (Sirr).
Category "A" welds are examined similar to ASME Section XI, except that the examination techniques ard personnel are to ha qualified for the detection of IGSCC.
Catcriory B Welds Category "B" welds are weldments that are fabricated from npo/ msg 88-01 rep I
i
i e
Resptv.se 'Ib Generic Ictter 88-01 NRC Position On IGSCC In NR Austenitic Stainless Steel Pipirg 4
Page 10 of 22 3
"rcnresistant mterials" but have receivM stress irprovement (SI) within 2 ears of operation.
%ese welds require an accelerated y
examination schedule.
We 24 Chtegory "B"
welds located in the Reactor Recirculation System were treated with IMuction Heating Stri s Irprovcment (IHSI) during a mintenance cutage in 1985.
Rese 24 welds nad accumulated 401.C days of operation prior to IHSI at 0
year limitation ard terporatures O /o 200 F, thus metirq the <.
therefore classified es Category "B".
'Ihese welds were examined for IGSOC b2 fore aM after IHSI with no flaws identifbye.
Cateaorv D Welds l
Category "D" Wolds are weldments that are fabricated from f
";wiresistant mterials with no SI".
Wese welds are wired to be examined at every recoM refueling cycle.
GGNS has 34 Category "D" welds that resulted frtn tN1 use of Inconel 182 weld mterial as a butter layer prior to mking the assembly welds.
'Ihese welds are located at interfaces between the reactor pressure vessel nozzles and tne safe ems or the safe eM to safe eM extensiorVpenetratiori seal.
Durirg GGNS's first refueling outage, these wr.lds were fully -
it.ed for IGSCC, except for limitations addressed by IRC approved relief request pirsuant to 10CFR50.55a(g).
No flaws indicative of IGSCC have 3
been iden 'W L
i have been performed for the detection of Currently, a, wlm*.ict, u a b RD3 0313, Revision 1 and Generic Intter
}
IGSCC u!. der
'idence of IGbCC.
In addition, GC2iS has j'
84-11 have #
a a
~~
npe# sg 88-01Irp i
Response To Generic Istter 88-01 NRC Position On IGSCC In IER Austenitic Stainless Steel Piping i
Page 11 of 22 1
performed augmented examinations exmacding the criteria of NUREG 0313,
' - c Revision 1 and Generic Istter 64-11 to enhance existi!q baseli.v3 data that has also confirmed the absence of IGSCC.
Based on current examination results, GGtG has no current plans to implemont a pipe replacement program.
%e use of Hydztgen Water Chemistry (HWC) has been evaluated at GGtG and we wil2. continue to monita industry experience with these systems.
However, there are no current plans to add a HWC system to GGtG.
We 34 Catego::y "D" welds are located in the annulus area between the reactor pressure vessel and the biological shield wall.
We weld locations and geometrical configurations have been evaluated by contractors representing both the DEI and MSIp processes.
All 34 Category "D" welds are acceptablo for the physical inplementation of either SI Ocess.
Additional evaluations have been initiated to evaluato the sustained stress load magnitudes to determine the effectiveness of stress inprovement.
GGG is currently assessing the performance of SI for interaction with plant outage schedules.
Any future actions to inplement SI for the Category "D" welds will te in empliance with Generic Istter 88-01 or other NRC approved programs.
III. GENERIC IEl%ER 88-01. ITTE 2 An T'.. servi Inspection (ISI) Plwaua to be implemented at the next i
refueling outage for austenitic stainless stoel pipire oevered under the npo/nsg 83-01 rep I
t
Response Tb Generic Istter 88-01 NRC Position On IGSCC In IMR Austenitic Stainless Steel Piping 4
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Page 12 of 22 3
I scope of the letter that conforns to the staff positions on inspection schedules, methods and personnel, and sample expansion included in this letter.
SERI's RESPONSE:
The current GGNS Inservice Inspection Program, Specification M-489.1, is in ocmpliance with previous ocmitments nade to NURPG 0313, Revision 1 and Generic letter 84-11.
Specification M-48).1 will be revised to i
incorporate the requirenents of Generic Istter 88-01 prior to the next refueling outage, currently scheduled for early 1989.
Examinations aJd examination schedules of welds under the scope of Generic letter 88-01 will be performed in accortlance with the requirements of ASE Section XI, with relief as prcsvided for in 10CFR50.55a(g)5, and the augmented requirements of Generic Istter 88-01.
Examination of lorqltudinal seam welds (Category "A") will be to the extent described in ASME Section XI, IWB-2500, Examimtion Category B-J, Item No. L9.12.
1 The Ataff Position on Inspection Methods anct Personnel indicates that the j
det led procedure, equipment and examination personnel shall be qualified by a formal program graved by the NRC such as that being conducted in accordance with the NDE Coordination Plan agreed upon by i
NRC, EERI, and the Boiling Water Reactor Owners Group for IGSCC research, l
being implemented at the EPRI NDE Center in Onrlotte, North Carolina.
I The NDE Coordination Plan states "The purpose of this plan is to coordinate selected NRC, EPRI, and the B@OG activities in regard to npe/ msg 88-01rty
}
Response To Generic Intter 08-01 1
NRC Position On IGSCO In IER Austenitic Stainless Steel Piping Page 13 of 22 training and qualification of NDE personnel ertployed in, perfor::ance of l
ultrasonic examination of piping eldments during inservice inspection of BWR power plants."
'Ihe NDE Coordination Plan being implemented at EPRI provides for the qualification of personnel.
In addition, EPRI has provided a module entitled "Generic Promedural Elements and Parameter Ranges For Detection and Discrimination of IGSCC" that provides the r-cary examination parameters for an IGSCC a.xamination.
'Ihe EPR.!
j program also provides a Parformance Documentation Sumary (PDS) that i
allows the utilities to verify that eminers are corducting exaninations in the same manner in whidt they performed their qualification practical.
GGNS utilizes the NDE Coordination Plan as described above.
Procedures used at GGNS for the detect-1 or sizing of IGSCC are reviewed against tne EERI module to ensure that the weary paraneters are included.
The PDS is usai to verify that examinations are being conducted in the 3
same rmnner coincident with the parameters ud in the practical portion of personnel qualification, GGNS Categories "A" and "D" cuitain welds with CRC and Inconel butter, respectively.
'Ihese welds are examined with personnel that have been qualified in auctrdance with the NDE Cbordiaation Plan with aMitional training provided by the contractor because of the unique material configurations.
'Ihe wrruit EPRI training aid qualification prtgrams utilize service removed sanples that cotAain IGSCC flaws.
Service rtrued saTples for welds containing IGSCC in welds with CRC or Inconal butter are not available ard testing for this material configuration la i
not provided.
Use of EFRI qualified perra.ncl with the dditional npe/ msg 88-01 rep
e i
Response To Generic letter 88-01
}mC Ebsition On IGSCC In BWR Austenitic Stainless Steel Piping Page 14 of 22 3-training is believed to be sufficient for extending the dism M qualification program to incitdo welds containing CRC or Inconel butter.
Conformance with the NRC Staff Position is maintained by inplementation of the NDE Coordination Plan as discussed above.
All future e aminations, for the purpose of InSCC detection, will be perfonned to the requirements of Generic Letter 88-01 as expressed in this response..
Sanple expansion, if required, will ocmply with the Staff Position on Sarple Expansion.
IV.
GDTERIC IRITER 88-01, ITD4 3 i
l A change to the Technical Specificationn to include a statement in the 1
section on ISI that the Inservice Inspection Program for piping covered l
by the scope of this letter will be in confomance with the staff positions on schedu. e, methods and personnel, and sanple expansion l
included in this letter (see enclosed model BhR Standard 'Ibchnic,il Specification).
It is recognized that the Inservice Inspection and
'Ibsting sections may be reroved frm the 'Iwinical Specifications in the future in line with the 'Ibchnical Specifications Inprovement programs.
In this case, this requirenent shall renain with the ISI se ion A n it is included in an alternative document.
SERI's RIEFONSE Improvements in 9tchrical specifications by placirs sane actions in administratively controlled prograns is a goal at GGNS.
In keepirg with this effort, SERI considers the appropriate location for costitments npe/nsg 889G3 rep I
i
Response 'Ib Generic Istter 88-01 NRC Position On IGSCC In BWR Austenitic Stainless Steel Piping Page 15 of 22 I
i regarding confomance to staff positions on schedule, methods and personnel, and sanple expansion to be the ISI pi@ain for GGIS.
'Ibe ISI program is a formal program that is reviewed by the NRC and currently controls other commitments that augment ASME Section XI Inservice Examinations.
'Ibe ISI Program for GGNS will be revised to incorporate the positiens contained in this report.
V.
GDIERIC IEITER 88-01, ITD14 Confirmation of your plans to ensure that the 'Ibchnical Specification Islated to leakage detection will be in confomance with the staff position on leak detection included in this letter.
I i
S GI's RESPONSE For the purpose of clarification, SGI's response to item 4 of Generic Letter 88-01 will address each requirement of the NRC's Staff Ibsition on leakage Detection:
NRC REQUIRDEff I
Isakage detection systems should be in confoman with Position C of Regulatory guide 1.45 "Reactor Coolant Pressure Boundary Isakage Detection Systems," or as otherwise previously approved by the NRC.
SERI RESEQISE npc/ reg 88-01 rep
Fesponse To Generic Istter 88-01 f
NRC Pocition On IGSCC In BWR Austenitic Stainless Steel Piping Page 16 of 22
'Ihe GGG leakage detection systems are in conformance with Position C
[
of Reguhtory Guide 1.45, with the exception of Regulatory positions la, 6, and 7.
'Ihe exceptions to Positions la and 6 have been accepted by the NRC and are noted in UFSAR Appendix 3A, "Cbnformance with IRC Regulatory Guides" (page 3A/1.45-1).
'Ihe exception to Ibsition 7 is that the drywell equipnent drain surp level indication is located in the Auxiliary building.
A 10CFR50.59 Safety Evaluation has been performed for this ex ption to Position 7, and a chanJe to the GGE UISAR that will reflect this exception is being subnitted to the NRC in the current update.
J NRC REQUIRDeff Plant shut down should be initiated for inspection ard corrective i
action when, within any period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or less, any leakage
(
detection system indicates an increase in rate of unidentified leakage l
in excess of 2 gpm or its equivalent, or when the total unidentified leakage attains a rate of 5 gpn or equivalent, whichever m,ws first.
For sump level monitoring systems with fixed-measurement-interval methods, the level should be monitored at a[ proximately 4-hour intervals or less.
SERI RESIOEE 1
GGNS Technical Specification 3.4.3.2 requires the plant to identify t
i ;
the leakage source within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or be in hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and cold shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with a reactor npe/mg 88-01 rep I
O Response 'Ib Generic letter 88-01 NRC Position On IGSOC In IMR Austenitic Stainless Steel Pipirg Page 17 of 22 f
coolant system unidentified leakage increase greater than 2 gpn within any 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> period. 'Ihis 'Ibchnical Specification also states that with greater than 5 gpn unidentified leakage, the leakage rate is to be r%A to within the limit within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or be in at least hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and cold shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
'Ihe GGNS 'Ibchnical Specification allowable leakage rates fran the reactor coolant systan have been based on the prailcted and experimentally otserved behavior of cracks in pipes.
'Ihe nomally expected backgreurd leakage due to equipnent design and the detection capability of the instrumentation for determining system l
leakage was also considered.
'Ihe evidence obtained frun experiments suggests that for leakage saneshat meater than that specified for unidentified leakage the probability a small that the imprefection or crack associated wi!.. such leakage would grow rapidly.
However, in all cases, if the leakage rates exceed the values specified or the leakage is located and known to be pressure boulxiary leakage the reactor will be shut down to allow further investigation and corrective action.
Service sensitive reactor coolant system Type 304 and 316 austenitic stainicss s+. eel piping, i.e.,
those that are subject to high stress or that contain relatively stagnant, intennittent, or low flow fluids, requires adaitional surveillance and leakage limits as described in GGNS Technical Specification 3.4.3.2.
The laakage detection systems addressed in GGNS Technical Specification 3.4.3.2 are sunp level monitoring efstems, arx1 level is monitored at least once per 4 inirs per GGNS 'Ibchnical Specification 4.4.3.2.1.b.
SERI has determined that the existing technical specifications provide adequate nonitor!nj to enable detection of a througrr.vall pipe crack.
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NRC RB2UIRDeff Unidentified leakage should include all leakage other than:
(a) leakage into closed systems, such as ptmp seal or valve packing leaks that are captured, flow metered, and enducted to a stmp or collection tank, or (b) leakage into the containment atrosphere from sources that. are i
both specifically located ard known either not to interfere with l
the operations of unidentified leakage monitorirn systems or not to be fran a throughwall crack in the piping within the reactor coolant pressure boundary.
SERI RESKtEE GGNS considers identified leakage as (Ref: GGNS Technical Specification 1.18):
(a) Isakage into collection systens, stx:h as punp seal or valve packirg leaks, that is captured and conducted to a sunp or collecting tank, or (b) leakage into the drywell atmosphere fran sources that are both specifically located and known either not to interfere with the operation of the leakage detectim systers or not to be pressure boundary leakac,e.
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Unidentified leakage is all leakage which is not identified leakage.
l It should be noted that the valve packing leaks are not individually flow metered, but are monitored by equipnent drain sunp level.
'Ihis is an acceptable method for identifying leakage as not being a breach of the reactor coolant pressure boundary.
NRC REQUITOGIT i
For plants operating with any IGST Category D, E, F, or G welds, at least one of the leakage measurment instruments acwiated with each sunp shall be operable, and the outage time for inoperable instruments shall be limited to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or innediately initiate an orderly shutdown.
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SERI RESPONSE i
l OGNS Technical Specification 3.4.3.1 (TS 3.4.3.1) requires tnat three systems capable of detecting leakage in the drywell be operable (drywell atmosphere particulate radioactivity, drywell and equipnent drain sunp level and flow, drywell air coolers condensate flw rate or drywell atmosphere gaseous radioactivity).
'Ibese systens have significant diversity in detecting reacter coolant pressure boundary leakage.
With one of the three systems inoperable of TS 3.4.3.1 cperation may continue for 30 days.
With tt.o of the three systems of
'IS 3.4.3.1 inoperable G@S nust be in hot shutdcwn within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Additionally, a l
pressure above the nomally indicated valueo will indicate the presence of a leak within the drywell.
Also, a drywell anbient npe/neg 88-01 rep l
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NRC Position On IGSCC In IMR Austenitic Stainless Steel Piping Page 20 of 22 t
taperature rise will indicate the presence of reactor coolant or steam leakage..
A taperature rise in the drywell is detected by monitorirg the drywell taperature at various elevations, inlet and outlet air to the coolers, and the drywell chilled water taperature increase between inlet ard outlet to the coolers.
Detection of small leaks has been shown to provide an early warning to prevent gross reactor coolant pressura boundary (RCPB) failure.
Small l
leaks (5 gpn and less) are detected by taperature and pressure changes, drain punp activities and increased air borne radioactivity in the drywell.
Experimental evidence has shown that for unidentified leakage screwhat greater than 5 gpa the probability is small that the crack or ir. perfection associated with this leakage would grow rapidly (CGNS %:hnical Specification Bases 3/4 4.3.2).
Additionally, GGNS l
has only a small number of Category D welds that are susceptible to IGSCC.
1herefore SERI considers a 30 day inoperable allowance for the drywell and equipent drain sunp level ard flow monitoring to be i
acceptable.
VI.
GENERIC IEITE 88-01. ITIN 5 In accordance with 10CFR50.55a(o), your plans to notify the NRC of any flaws identified that do not meet IWB-3500 criteria of Section XI of the code for contimed operation without evaluation, or a cW found in the condition of the welds previously known to be cracked, crd your l
, l evaluation of the flaws for contimed operation and/or your repair plans.
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Response 'Ib Generic I.etter 88-01 NRC Position On IGSCC In EHR Austenitic Stainless Steel Piping i
Page 21 of 22 SIRI's RESPONSE In the event GGNS identifies IGSCC flaws exceeding the acceptance i
criteria of IWB-3500, the NRC shall be notified as required by Generic Istter 88-01.
If continued operation is permissible based on evaluations performed in accordance with IWB-3640 or repairs made in acoottlance with INA-4130, NRC approval will be obtained prior to resunption of operation.
Flawed pipe analysis and weld overlay repair design will be performed in accordance with the criteria presented in NURDG 0313, Revisien 2 with the following additions and clarifications.
- 1. For flawed pipe analysis involving weldments with nominal diametets smaller than 12 inches, representative butt weld residual stress distributions given in industry literature will be used.
- 2. In the determination of crack tip stress intensity, KI, for the prediction of IGSCC crack growth will be used, i
KI = KIA + KIR where i
KIA = stress intensity factor due to applial 1 cads including pressure, dead weight, differential thermal expansion, and I
cuerlay axial shrinkage KIR a stress intensity factor due to residual stress Mm/ msg 88-Olrep P
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- 3. In the prediction of fatigue crack growth, a fatigue crack correlation representative of actual plant conditiers will be used.
- 4. Predicted IGSCC and istigue crack growth depths will be cxxnbined per the methodology pmvided in ASME (1986 Edition),Section XI, Appendix I
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