ML20059L667

Inservice Insp Program,Byron Station Units 1 & 2

ML20059L667
Person / Time
Site:	Byron
Issue date:	09/10/1990
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20059L664	List: ML20059L661 ML20059L667
References
NUDOCS 9009270248
Download: ML20059L667 (10)

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Enclosure Byron Station Units 1 and 2 ISLErogram Summary Relie0RequeaWR-121Resisiott2 blander-URevisionEA), are being tabmitted in order to upgrade the B:rron Station ISI Program to reflect changes made to the Braidwood ISI Program based on NRC comments and requests for clarification.

The change to Relief Renuest NR-12 is identifying the alternate test method on the Resic.ent Heat Removal Heat Exchanger nozzle-to-shell welds. The change is from visual examination to a "best effort" ultrasonic examinat'on (UT).

Relief ReauestEE-l is a new submittal which is similar to the Braidwood Relief Request SR-1. The purpose of this relief request is to exempt snubber pipe clamp insulation removal solely to perform the required visual examination (VT-3/4), provided the alternate test method in part 6 is performed. The previous SR-1 Relief Request for Byron Station had been deleted due to lack of supporting field inspection information. This information is now available and is contained in the new Relief Request SR-1 (Revision 6a).

The proposed relief requests provide adequate testing to maintain assurance of component operability without causing excessive radiation exposure to inspection personnel.

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RGv.12b RELIEF REQUEST NR-12 b , 1. EXETZK1 Feedwater- and Main ' Steam (Steam Generator, Secondary Side);

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Residual Heat Removal (Residual' Heat RemovalLHeatExchanger)

2. NUMBER OF 1TEMSt 8

.o Component Nn=her Item Number ~ Attachment Nn=hers 1RC-Ul-BA SGN-02, SGN-03 1&2 2RC-01-BA. SGN-02, SGN-03 1&2

.1RH-02-AB RHKH-01, RKKN-02 3 2RH-02-AB RHKN-01, RKKH-02 3 i

3. ASME-CODE CLASS: 2 1 ASME CODE SECTION KI REQUIREMENTSt Subsection IWC, Table IWC-2500-1, Examination Category C-B, Item C2.22 requires volumetric examination of the regions described in Figure IWC-2500-4(a) or (b), for inner radius in nozzles w;thout reinforcing plate in vessols > 1/2 in. nominal wall thickness. ' Item C2.31 requires surface exmnination of the regions.

described ir Figure IWC-2500-4(c), for reinforcing plate welds.in vessels > 1/2 inch nominal wall thickness. Item C2.32 requires volumetric examination of the regions described in Figure IWC-2500-4(c) for nozzle-to-shell welds with Reinforcing Plate in.. vessels > 1/2 inch nominal wall thickness. Examinations are conducted on. nozzles at terminal ends of piping runs-selected for examination under' Examination Category C-F, each inspection interval. In rddition, Examination Category.C-H, Item C7.10 requires a system leakage test, (IWC-5221) each inspection period for pressure vessel pressure retairing components.

.5. RASIS FOR RELIEF: The nozzles listed above contain inherent geometcic. I constraints which limit the ability to perform meaningful ultrasonic )

examinations (UT).

l The feedwater nozzle (SGN-02) has an internal multiple venturi type . -

flow restrictor and an internal thermal. sleevel see Attachment.1. This design can not be ultrasonic 1y examined due to the internal geometry of.-  !

-the nozzle. J

' The main steam nozzle (SGN-03) has an internal multiple venturi type-flow restrictor with an equivalent throat diameter of 16 inchess Attachment 2. This design limits the flow in the event of a. postulated:

steam line break. This design does not use a radiused' nozzle as #

described in figures.IWC-2500-4(a) or (b). It has seven individual  !

venturi, which can not be ultrasonic 1y examitted. l The Residual Heat Removal Heat Excharger (RHR HK) nozzle-to-shell (REKN-01 ar.d RKKN-02)' configuration has a reinforcing pad on the inside of the shell; Attachment 3. This configuration differs from figures IWC-2500-4 (a), (b), and (c). A reinforcing plate weld surface j '

examination can not be done because the plate is on the inside of the HK. An' inner radius UT can not be done because of the reinforcing.

plate location. A nozzle-to-shell UT does not achieve full ASME coverage of the weld area.

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(008BD/0034D/082490) 2.7 - page 63 of 80 l

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Rov. 2b 6.- ALTERNATE TEST METHODI ; Visual esamination (VT-1) shall be performed either directly or indirectly to the extent practical when a c aponent

'is disassembled for maintenances VT-1 not to exceed once per' inspection -

.ig ' interval. . Visual esamination (VT-2) shall be. performed each inspection-k period oniall pressure retaining components. And a best effort UT shall.be performed on the RHR HK nossle-to-shell welds-on a frequency consistent with ASME Section XI.

7. @jilIFICATION: The VT-1 will provide early detection of detrimental flaws, and-the'VT-2 will detect through wall leakage. The best effort

.UT will detect flaws in the RHR EK nossle-to-shell weld material..

8. APPLICABLE TIME PERIOD - This relief is required for the first 120' month inspection interval.

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(0088D/0034D/082490) 2.7 - page 64 of 80

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. -" ? ' RQv. 60 Ponding Approval.

>Rallef Request SR-1 fl. SYSTEM ' AB', CV; DO, TW, MS, RC, RH, RY, SD -

1 2.- NUMBER OF ITEMS: .All~non exempt portions of safetyLrelated snubbers'in 3

.the,following, systems:

System Snubbers Attached to ';

Insulated Pipe-  !

Unit 1 Unit: 2

• AP 1 0 cv 27 40 DO 6 12 rw 2 23  !

MS 4 12 RC- 49 63 RH 5 .17 RY 19 14 SD 2 13 Total snubbers on insulated lines 115 194 q=

Total snubber population- 275 302 Table showing the number of snubbers on-insulated . lines. vs. the total-number of snubbers in the population. The above numbers will-_ vary with ,,

time as a result of snubber reduction and other plant modifications. {

3. ASME CODE CLASS: '1, 2 and 3.

4. ASME SECTION XI CODE DEQUIREMENT3 The component support examination' boundaries.are defined by IWF-1300 and Figure 1300-1. Per IWF-1300e, the IWF support exam boundary for _ snubbers which'have non-integral ,.

attachments extends: f rom the. contact surf ace between- the component and

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4 the support to the surface of.the building structure.-

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5. BASIS FOR RELIEF: The visual examination of an integral er non-integral pipe attachment is limited by-the-insulation installed on -

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the piping. It would impose a great deal of hardship in terms.of 4 manpower, time and radiation exposure to remove 11nsulation to visually- .!

' inspect all. snubber pipe clamps particularly if there are alternative methods that provide an equivalent _means of. determining pipe clamp

integrity.

The ma{ority of snubbers are located inside Containment in high radiation areas. Removing insulation on all~ snubber pipe clamps would

. require one Hteith Physics Technician to survey the insulation prior to its removal and then a two man insulator crew to remove the insulation. This would add three people to the customary two man.

inspection crew, which would more than double the man rem exposures for performing the surveillance.

(0103D/0036D/082490) 6.4 page___of___

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-The CECO SPPM VT-3/4 procedure allows remoto-inspections 1 to be 4

performed on. snubbers that are out of reach for: direct inspection.,

Scaf folds or man baskets = would have- to be used to remove inulation on -

remote snubbers. Extra scaffolds built for snubber' pipe clamp 1n insulation removal would increase congestion in containment \ end 9" M M increase the amount of material being handled and surveyed d d ng the

, outage. -It would also produce additional DAW and result in more-y . scaffold material acquiring fixed contamination during the outage. .It B would pose an' additional; burden on the examination in terms-of manpower, time, safety and radiation exposure. It also defeats

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the purpose of the remote examination methods allowed in the SPPM.J

6. ALTERNATE TEST METHOD: ASME Section XI Code, IWA-2240,': allows _for alternate examination methods if they_ provide results'that are equivalent to the specified method. - In lieu of removing insulation on snubber pipe clamps, the followlag alternate exam methods will be-m: employed.on all snubbers that aretaccessible for direct examinations

a. A hands-on inspection of the pipe clamp will-_be performed to l verify the clamp is tight. l I

b. Clamp alignment with the loadipin axis will be observed to ,!

verify alignment is within design tolerances. i

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c. The load 7 1n/ stud will be inspected to verify its integrity, i!

This will insure that parts are in place and that the pin is  ;

tight. -If~the load pin is obscured by insulation, the -- l .

y insulation will be removed or modified to allow for this inspection. j

-d. Insulation will be checked for evidence of damage due to' slipped ;ij or' loose clamps. l

e. If boric acid contamination.or corrosion is observed, insulation ]

will be removed to inspect:the pipe clamp.

7. JUSTIFICATICM This relief request is intended for non-integral i, attachments on insulated lines. The visual inspection.of snubbers are "f!

performed using the CECO SPPM VT-3/4 procedure. The inspections are- [j performed on .all safety related. snubbers every 18 months i 25% or more ,

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frequently per Byron Station Technical Specifications'. Under this- i procedure, support indications to-be. observed and documented-include f s

the following i

- cracks, pitting ja

- erosion, corrosion, wear 3

- loose, missing, damaged parts

- contamination, debris i>' - weld degradation j'

- slipped clamps

- are strikes, weld spatter, pein't

- clearances, settings

- condition of epherical bearings s

-(0103D/0036D/082490) 6.4 page o f ____

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Posding'ApprovQl: -

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The proposed alternate exam methods listed-in part:6 of the Relief Request enhance,the SPPM VT-3/4 inspection procedure. The hands on -

check combined with the VT-3/4 procedure will' insure that snubber pipe, clamps'arel installed an.1 secure on snubbers that.can-be reached for. ll*

direct osamination. If'there.'are'any indications of degradation, tho' insulation-will be< removed to allow for a total clamp inspection.

For the snubbers that have pipe clamps completely buried in insulation, the insulation will be removed for a complete inspection.- Based on'a review of the piping line list and snubber data bases, this condition occurs.primarily on PSA-1/4 snubbers attached to 1 inch or,less piping, covered with 2 inches thick.or greater insulation. Insulation remoral to inspect these pipe clamps will'be accomplished.several ways. When these snubbers are removed for functional testing, the insulation will have:to be removed to unpin the snubber. The visual-inspection of the.

pipe clamp will be performed at this time. Visuals on pipe clamps will-be coordinated with the;NDE inspections when insulation-removal to e access welds:also' exposes the pipe clamp for inspection.- Snubber exams are-documented-so it can be verified that all snubber pipe clamps.

completely buried in insulation receive a visual inspection within the ten year interval.

On scubbers.that=are inaccessible for direct examination, a remote esam

-will be performed per the SPPM VT-3/4 procedure. This would include snubbers on overhead runs of piping that are out of reach. ,The number of snubbers in this category represents only-about 5% of the snubbers-in Units 1 and 2. None of these snubbers'have pipe clamps completely.

buried in insulation. They are not in high traffic areas where

~ typically' the most clamp slippage and other damage is experienced.

Boric acid spray from valves or-flanges is'also less;likely'on the the majority,of'these snubbers. Because they areLin relatively safe areas, an indirect inspection-verifying no. outward indications are.~present will demonstrate that the pipe clamps are' secure. :When these snubbers are fw ctionally tested, scaffold will be built to access them.. A ,

hands-on exam of the pipe clamp will be done at that time. -If any of the above conditions are present, scaffold'will be built-.to more thoroughly investigate-the indication.' y

[ . I 1 Previous inspection experience has not shown-an increasing ~ trend in j regard to loose pipe clamps. A review of-earlier data: indicates that'  !

the incidence of. loose pipe clamps is rare. The alternate methods proposed in this relief request combined with the-commitmentyto remove

-insulation on those pipe clamps completely obscured by insulation will i provide a complete examination of the entire snubber population in Units 1 and 2. This approach meets the requirements of'an alternate ,

inspection and will provide a high degree of confidence that the. 1 snubber pipe clamps are in place-and secure. By limiting the number of i people required to perform the surveillance, the proposed methods will-minimize man rem exposures.

4 (0103D/0036D/082490) 6.4 page of

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Rov. 60 Pending_ Approval

They will e31minate the need for' additional' scaffolding,-which will' lower:the amountcof contaminated material produced during the outage, and reduce.the traffic and congestion associated with moving' scaffolding in-and out of Containment. This will promote the: efficient: ,

and cost offective execution of.the-visual.surveillances.. - -;

8.' APPLICABLE TIME PERIOD: This request for relief applies for the firsti i ten year. interval.

l-(0103D/0036D/082490) 6.4 page_ of