ML18030A055
| ML18030A055 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 06/30/1981 |
| From: | Curtis N PENNSYLVANIA POWER & LIGHT CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0313, RTR-NUREG-313 GL-81-03, GL-81-3, PLA-856, NUDOCS 8107020353 | |
| Download: ML18030A055 (7) | |
Text
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REGULATORY INFORMATION DISTRIBUTION SYSTEM'RIOS)
ACCESSION'BR+ 8107020353:
OQC ~ DATE: 81/06/30 NOT'ARIZED:
NO FACIL::50 387 Susquehanna Steam Electric Station< Unit 1< Pennsylva 50 388 Susquehanna Steam Electric Stationt Unit 2< Pennsylva AUTH'AME'UTHOR AFFILIATION CRUTIS g i4e W ~
Pennsylvania Po~er 8 Light Co<
RECIP ~ NAME-RECIPIENT AFFILIATION SCHWENCER i A ~
Liicensing. Branch-2 SUBJECT!'ot wards t'esponse'o NRC Genet ic Ltr 81 03 8
NURKG 0313'Technical Rept on Matl Selection 8 Pt'ocessing Guideilines for BWR'oolant Pressure Boundary Piping."
DISTRIBUTION CODE; B0018 COPIES RECEIVED;LTR ENCI SIZE'.'
TITLE PSAR/FSAR AMDTS and Related Cort espondence DOCKET' 05000387 000 88 NOTES:Send IKE 3. copies-FSAR IL all amends-,
1 cy:BWR LRG PM(CRIB) 05000387 Send IEE 3 copies FSAR tt all amends F 1 cy;BWR-LRG PM(1. CRIB) 05000388 RKCIP IENT IO COOK/NAME!
ACTIONt A/O. LICENSNG.
LIC BR ¹2'-A INTERNAL: ACCID KVAL BR26 CHEM ENG BR 11.
CORK PERF BR 10 EMRG. PRP DEV 35'QUIP QUAL BR13i GKOSC IENCES 28 HYO/GEO BR 30
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TWO NORTH NINTH STREET, ALLENTOWN, PA. I 8 I 0 I PHONEr {215) 770-5151 NORMAN W. CURTIS Vice President-Engineering 3 Construction-Nuclear 770.5 381 June 30, 1981 Mr. A. Schwencer, Chief Licensing Branch No.
2 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
20555 SUSQUEHANNA STEAM ELECTRIC STATION
RESPONSE
TO NRC GENERIC LETTER 81-03 AND NUREG 0313 "TECHNICAL REPORT ON MATERIAL SELECTION AND PROCESSING GUIDELINES FOR BWR COOLANT PRESSURE BOUNDARY PIPING" ER 100450 FILE 841-9,883 PLA-856 8II1-13 Attached please find PPsLrs response to Generic letter 81-03 and NUREG 0313 Very truly yours, N.
W. Curtis Vice President-Engineering 6 Construction-Nuclear TEG/mks Attachment
~,oi
>0 7 II 7 0 35'ENNSYLVANIAPOWER 3
LIGHT COMPANY
THE EFFECTIVE ELIMINATION OF IG"CC AT SUSQUEHANNA STEAN ELECTRIC STATION Since
- 1975, when knowledge of intergranular stress corrosion cracking (IGSCC) in austenitic sta'nless steel in boiling water reactor (BWR) piping was brought to its attention, Pennsylvania Power
& Light Company (PP&L) has undertaken an extensive program.
for the Susquehanna Steam Electric Station to ef ectively eliminate the possibility of IGSCC-caused
- downtime, and also to conform to the requirements of NUREG-0313, Rev.
1, and previous publications.
\\
PP&L's program of IGSCC mitigation includes the fol'owing methods materials that conform to Section III of NUREG-0313.
A.
Recirculation system discharge valve bypass line (4")
replaced with carbon-limited Type 304 SS (low carbon stainless steel that meets the mechanical properties of regular grade Type
- 304, and has a maximum carbon content of.03%).
B.
Core Spray and Head Spray-replaced with carbon limited Type 304.
C.
Reactor water clean-up system (RWCU) replaced with Tyne 304L SS.
D.
Instrument piping and bottom drain replaced with Type 304L SS.
Any further replacement of nonconforming material would result in what PP&L feels is an undue hardship, because it would involve replacement of already-installed large diameter (20" or larger) piping or flued heads that are imbedded in concrete.
.In view of the above reasons, and with consideration or the very extensive effort by PP&L that resulted witn the replacement of. a considerable amount of nonconforming material, PP&L requests that furtner material replacement requirements not be imposed (Generic Letter 81-03) because o
severe undue hardship.
2.
El'm'nation of lines whose functions are no longer required.
A.
Control Rod Drive Hydraulic Return.
3.
Use of low carbon corros'n resistant weld build-uv (shop method) for field welds.
A.
Recirculation system risers.
o
4.
Design improvement to el minate crevices.
A.
Recirculation system inlet safe ends (extensive modifica-tion to replace all safe ends and thermal sleeves).
5.
Solution heat treatment.
A.
Recirculation system risers (shop welds)
In addition to the mitigation methods listed above, PPGL has used several
- more, some of which are listed under Section V of NUREG-0313, as follows:
6.
Dissolved ox en control A.
During normal plant operation PP&L has relocated the control rod drive (CRD) pump intake from the condensate storage tank to the condensate makeup/reject line.
This results in using CRD water with the lowest oxygen concentration available (essen-tially water of feedwater quality).
B.
i During all phases of operation/shutdown except normal operation, oxygen levels are reduced by the use of a mechanical vacuum deaerator.
The deaerator is expected to maintain an oxygen content of less than 250 PPB during start-up, hot standby and shut-downs~
7.
lrleldin Parameters A.
Block weld'ng was prohibited.
B.
Interpass temperature was limited to 350'F maximum.
C.
No preheat was used (in excess of a.~orking range of 60'F to 150'F)
- 8. 'Ferrite Control All of the weld metal and all of the type 304/316 castings were specified to have not less than 5% ferrite content.
This level is generally recognized as sufficient to provide immunity from the initiation of IGSCC.
Use of induction heatin stress improvement (IHSI) 1HSI is a method of eliminating or substantially reducing residual tensile stresses on the inside surface of the piping. These tensile stresses are primarily caused by welding and have been identified as one of the three major causes of IGSCC.
PPaL is presently considering the use of IHSI for 108 welds on No.
1 unit that do not conform to Section III of NUREG-0313.
These welds are among a total of-110 welds of 4" diameter and larger that are presently scheduled to receive augmented inservice inspection (ISI) in accordance with Section IV.B.l.b of NUREG-0313.
The 110 welds are as follows:
1.
Recirculation system discharge valve bypass line 4-4" welds (HAZi s on weldolets) 2.
Recirc. risers 10-12" welds (HAZ's on sweepolets/
reducers).
3.
Core spray 4-12" welds (HAZ's on 316 SS flued heads) 4.
RWCU 6-4" welds (HAZ's on weldolets/flued heads).
5.
Residual Heat Removal (RHR) system 41 welds (20", 24").
6.
Balance of recirculation system 45 welds (4", 22",
28").
For No.
2 unit, PP&L intends to use the IHSI process for 103 out of a total of 105 non-conforming welds.
All 105 welds are also presently scheduled for augmented ISI.
The 105 welds are as follows:
1..
Recirculation system discharge valve bypass line 4-4" welds (HAZ's on weldolets).
2.
Recirc. risers 10-12" welds (HAZ's on sweepolets/
reducers).
3.
Core spray 4-12" welds (HAZ's on 3'6 SS flued heads).
4.
RWCU 2-4" welds (HAZ's on weldolets) 5.
Residual Heat Removal (RHR) system-40 welds (20",
24")
6.
Balance of recirculation system 45 welds (4"., 22", 28").
The only other known welds that do not conform to Section III are numerous small
( ( 2" diameter) socket welds, used mostly on in-strument piping.
Because of the difficulty with reflected signal interpretation due to their small size, they are exempt from the type of inspection (ultrasonic) that is meaningful for detecting the inside-surface originating IGSCC, and therefore, PPGL believes that augmented ISI is not reauired for these small welds.
The SSES leak detection system has been reviewed for NUREG-0313 compliance and it is our determination that the design conforms to the reguiremrnts of Section IV.B.l.a.