ML20206G504

Requests That Enclosures 1 & 2 Re 990412 Conference Call, Discussing Preliminary Results of SG Insp,Be Placed in PDR

ML20206G504
Person / Time
Site:	South Texas
Issue date:	05/04/1999
From:	Alexion T NRC
To:	NRC
References
NUDOCS 9905100037
Download: ML20206G504 (15)

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l May 4, 1999 I

MEMORANDUM TO: File ORIG. SIGNED BY

.FROM:

Tom Alexion j

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SUBJECT:

STEAM GENERATOR INSPECTION RESULTS, APRIL 12,1999,

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SOUTH TEXAS PROJECT, UNIT 1 i

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The NRC staff had a conference call with the licensee on April 12,1999, to discuss the l

preliminary results of the steam generator inspections. The licensee provided the information in j to facilitate the April 12,1999, conference call. On April 28,1999, the licensee provided an update to the information provided on April 12,1999. That information is in. The purpose of this memorandum is to place the attachments in the Public Document Room.

Docket No. 50-498 Attachments: As stated

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DISTRIBUTION:

(Dodett gg0-498) j l

PUBLIC h)l PDlV-1 r/f I

DOCUMENT NAME: 1:\\SOTEXAS\\MEM41299.WPD To recesve a ecpy of this document. Indcate in the box C= Copy w/o attachment /encbsure E= Copy with attachment / enclosure N = No copy kE,PDIV-D/LA _

E PDIV-1/SC OFFICE PDIV NAME TAlexi

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CJamerson h RGrammh DATE

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9905100037 990504 PDR ADOCK 05000498 P

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May 4, 1999 MEMORANDUM TO:Jillsjl?

FROM:

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m Alexion

SUBJECT:

STEAM GENERATOR INSPECTION RESULTS, APRIL 12,1999, SOUTH TEXAS PROJECT, UNIT 1 4

The NRC staff had a conference call with the licensee on April 12,1999, to discuss the l

preliminary results of the steam generator inspections. The licensee provided the information in to facilitate the April 12,1999, conference call. On April 28,1999, the licensee I

l provided an update to the information prov,ided on April 12,1999. That information is in. The purpose of this memorandum is to place the attachments in the Public Document Room.

Docket No. 50-498 Attachments: As stated t

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@Asife 512 972 8179 P.02/06 NRC PHONE DISCUSSION -1RE08 STEAM GENERATOR TUBE INSPECTION RESULTS APRIL 12,1999 j

1.

Primary to Secondary leakage prior to shutdown.

STP 1RE08 - Leak rate during the just-completed Uriit 1 Cycle B was a fraction of a gallon per day (see attached graph). Calculated leak rate with stable tritium I

concentration in the primary was less than 0.25 gpd during the first third of the cycle.

l Over the final two-thirds of the cycle, there appears to have been a small increase in the j

leak rate to about 0.5 gpd. (Quantification of a change this small is uncertain since a change in the secondary make-up rate will change the primary-to-secondary tritium equilibrium and the make-up rate measurement is not very precise.) Higher leak rate values were calculated when the primary tritium concentration significantly decreased due to a down power, but they are not valid since the primary and secondary tritium concentrations were no longer in equilibrium. We are confident the actual leak rate never exceeded a fraction of a gallon per day. Primary-to-secondary leakage integrity was very good right up to the end of the cycle.

2.

Results of secondary side hydro.

i STP 1RE08 - STP does not routinely perform secondary side hydros during steam generator inspections. Eddy current testing of tubes and visualinspection of previously installed plugs are employed to ensure primary-to-secondary integrity.

I in this outage, all plugs were visually examined for signs of leakage. No defective plugs were identified.

3.

For each SG, provide a general description of areas examined, include expansion criteria and specify type of probe used in each area.

STP 1RE08 -This was the third STP Unit 1 inspection where the voltage-based repair criteria was applied. Also, this was the first Unit 1 inspection where NEl 97-06 was formally implemented. The Inspection Plan was as follows:

• 100% bobbin fulllength -(except for Row 1 & 2 U-bend).

• 100% H/1. Top-of tubesheet by RPC.

~43% C/L Top-of-tubesheet by RPC in SGs 1 A and 1B only.

e Expansion Criteria: Inspect 100% in SGs with crack indications; 20% in SGs 10 &

1D. (No expansion was required.)

100% Row 1 & 2 (small radius) U-bend by + Point.

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100% of freespan dings >5 volts by + Point.

100% of tubesheet region, full depth, for hot leg wavy tubes by RPC.

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4.

For cn:lyzed EC results, describe bobbin ine'irati ns (thase not cxrmined with RPC) and RPC/Plus Point /Ceccoindirti:ns. Include the fall: wing infermatisn:

location, number, degradation mode, disposition, and voltages / depths / lengths of l

the most significant indications.

STP 1RE08 - The only bobbin indications not examined with RPC or + Point are as i

follows:

DSls less than 1 voit (per valtage-based repair criteria) e i

MBMs that are unchanged from the baseline & Dings 5 volts and under (bobbin is qualified to detect axialindications through five voit dings).

f AVB wear indications (Note that a 20% sample cif AVB wear indications was examined by +Polni. Note also that all Preheater wear indications were examined by

+ Point.)

l PRELIMINARY !nsWlon results are as follows:

PROGABLE DEGRADATION MODES FOR TUBES TO BE PLUGGED"*

PROB. DEG MODE SG1A SG1B SG1C SG 1D TOTAL H/L TTS Cire. ODSCC 1

3 16 4

24 H/L TTS Axial PWSCC 5

3 8

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H/L TTS Vol.

1 1

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TSP ODSCC*'*"

6 5

20 " ' *

• 8 39 C/L Freespan ODSCC-Axial 2

2 2

6 C/L Freespan Other 1

1 l

C/L Freespan Vol 3

5 2

10 U-Bend Freespan Vol 1

1 H/L Freespan Axial 1

1 j

H/L Freespan Vol 3

3 6

i H/L PWSCC in Tubesht-Axial 2

2 0

Loose Part Wear TOTAL DEFECTIVE:

17 25 37 20 99 i

Permeability (preventive plug) 23 " ' *

• 7 12 14 56 TOTAL:

40 32 49 34 155 I

H/L-Hot leg C/L-Cold leg TTS-Top-of tubesheet TSP -Tube Support Plate NOTE 1 - Plugging lists are nearly complete for SGs 1 A and 1B; however, a small l

amount of eddy current acquisition and analysis remains for SGs 1C and 1D.

NOTE 2 - Confirmed DSis greater than one volt (APC lower voltage repair limit).

i NOTE 3 - One tube left in service under F* In this Steam Generator, NOTE 4 - One tube had DSis over one volt that were confirmed by RPC at two different j

support plates.

l l

No defects identified by the cold leg top-of-tubesheet RPC sample.

I No defects identified in Row 1 & 2 U-bend examination.

~1267 tubes with DSI indications were left in service with bobbin voltage below the lower voltage repair limit (1.0 volt). Final data to be provided in 90 day report.

l One indication exceeded the upper voltage repair limit (4.0 volts this inspection) and

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will be plugged. (it did confirm.) 57 other indications exceeded the lower voltage I

APR-12-1999 12:44 STPEGS 512 972 0179 P.04/06 repair limit, cf which 39 have been confirm;d by RPC and will be plugg d. (A fsw more may also confirm as the specialinterest RPC in SGs 10 and 1D is completed.)

No PWSCC 0 TSPs, no cire cracks 0 TSPs, no axialindications extending outside

=

the TSP have been detected.

Conditional Burst Probability & EONC Leakage calculations not completed yet (required prior to mode 4). No difficulties expected in meeting voltage-based repair criteria limits. (Next cycle will be 333 EFPD or less.)

5.

Describe repair / plugging plans.

STP 1RE08 - All defects will be plugged; no sleeving will be performed this outage. See inspection Results Table above. Plugging will commence shortly.

8.

Discuss previous history; "look backs" performed.

STP 1RE08 - Look backs performed on all freespan DNis (dings with possible flaw indications) & freespan NQls (non-quantifiable indications), to confirm no change from the baseline.

7.

Discuss new inspection findings.

STP 1RE08 - No new degradation mechanisms identified.

8.

Describe in-situ pressure test plans and results, if available; include tube selection criteria.

STP 1 RE08 - In-situ test plans were developed for all active and potential damage I

mechanisms. There were no defects in SGs 1 A or 1B which challenged structural integrity criterla; however, one or more circumferential indications in SG 10 may require in-situ pressure testing. This will be discussed in the NEl 97-06 Tube Integrity Assessment to be issued following the outage. No proof pressure test candidates have been identified to date among the axial or volumetric indications.

9.

Describe tube pull plans and preliminary results, if available; include tube selection criteria.

STP 1RE08 - No tubes pulled. (reference letter to NRC from Steve Thomas dated 8/18/98-NOC-AE-000258) 10.

Assessment of tube integrity for previous operating cycle.

STP 1RE08 - Assuming favorable results from in-situ testing (if required) tube integrity appears to have been satisfactory during the preceding cycle. A preliminary evaluation against the NEl 97-06 performance criteria will be made prior to start-up, and a final Condition Monitoring Assessment will be documented in the NEl 97-06 Tube integrity Assessment Summary to be submitted following the outage.

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N's 11.

Asessament of tube integrity for next operating cy2ia.

STP 1RE08 - No conditions are expected that would impede full cycle operation in Unit 1 Cycle 9 (287 Effective Full Power Days planned; 333 EFPD possible with coastdown). A preliminary evaluation against the NEl 97-06 pelformance criteria will be made prior to ste rt-up, and the final Operational Assessment will be documented in the NEl 97-06 Tube irtogrity Assessment Summary to be submitted following the outage. Also, the 90 day report required to support Generic Letter 95-05 commitments associated with the voltage-based repair criteria will be submitted within 90 days of breaker closure. (These two 90 day reports may or may not be combined.)

12.

Provide schedule for steam generator-related activities during remainder of current outage.

STP 1RE08-Data acquisition and analysis is complete in SGs 1 A and 1B. SGs 10 and 1D will be completed by -4/13/99 Pressure testing (if required) will likely occur 4/12/99 (P.M.).

Plugging lists nearly completed for SGs 1 A and 1B. SGs 10 and 1D will be completed by ~4/13/99, Plugging will commence today, and is expected to be completed by 4/14/99.

e Manways will be installed 4/20 (0 midloop).

Mode 4 is projected on 4/21/99.

BACKGROUND INFORMATION ON STP UNIT 1:

CommercialOperation: 8/88 EFPY at 1RE08: 7.7 EFPY (Length of Cycle 8: 528 EFPD)

Model: Westinghouse Model E Tube Material: Alloy 600, mill annealed Tube Support Plates: Carbon Steel,with drilled holes Tubesheet expansion: full-depth hard roll.

Tw-3.93 EFPY at 623'F; 620'F since.

ID was roto-peened prior to commercial operation.

U-bend heat treatment of Rows 1 & 2 performed at first refueling outage.

Previous plugging history:

Tubes plugged prior to 1RE08:

1 A-101 (2.1%)

1B - 91 (1.9%)

1C -100 (2.1%)

1D-119 (2.4%)

TOTAL: 411 (2.1%)

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' Tom Alexian Attached is an update of the handout which was faxed for the phone call on 4/12/99. Below is a summary of the changes, which are marked with change bars. Please distribute to the others that were in the call. Thank you.

j Chet McIntyre l

SUMMARY

OF CHANGES:

Title - Changed " April 12,1999" to " April 1999."

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Question 4 Response, first bullet - Added "or equal to" to agree with STP Tech Specs l

Question 4 Response, Probable Degradation Modes Table -

> Deleted " Preliminary" from' the introductory phrase.

> Changed Title to past tense; spelled out " Probable"in column heading.

> Adjusted classification definitions for two categories: "H/L TTS Axial PWSCC" became "H/L TTS & F" Distance Axial PWSCC" while "HL PWSCC in Tubesheet - Axial" became "H/L PWSCC in Tubesht - Wavy Tubes". Because of this change, counts in SG1A changed in

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these categories. Also, since this leaves no category into which F" tubes would otherwise fall, Note 3 was deleted (i.e., changed to a bullet following the table).

l

> Spelled out " Volumetric" wherever it appeared in this table.

l

> Corrected the TSP ODSCC count in SG 1C from 20 to 19 per plugging list.

> Updated the "C/L Freespan Axial ODSCC @ Ding" counts for SGs 1C & 1D per plugging list j

and made the title of this category more complete by adding "@ Ding." Added Note 5 to j

explain double counting of the two tubes with two pluggable defects.

l

> Updated the "C/L Freespan Other @ Ding" count for SG 1C per plugging list and made the title of this degradation mode more complete by adding "@ Ding."

> Updated the "C/L Freespan Volumetric" count for SG 1C per plugging list. Added Note 5 to l

explain double counting of the two tubes with two pluggable defects.

> Deleted the U-bend freespan Volumetric category, as it was determined that this indicati-was not a defect.

> Made the title of the "H/L Freespan Axial ODSCC @ Ding" category more complete by j

adding "@ Ding."

> Updated the "H/L Freespan Volumetric" count for SG 10 per plugging list.

> Updated the Total Defective tube counts per the above. Added Note 5 to explain double 4

counting of the two tubes with two pluggable defects.

I

> Added category to capture the preventive plugging of one tube in SG 1A due to the

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recommendation of the Owner's Level til stemming from his oversight review.

> Updated the " Permeability" category count for SG 1D per plugging list. Deleted Note 3, since F* does not apply to preventive plugging.

> Updated the " Total Plugged" counts per the above.

> Revised definition of TTS to clarify that this designation refers specifically to the expansion transition.

Question 4 Response, NOTE 1 - Updated to reflect completion of final plugging list.

Question 4 Response, NOTE 3 - Deleted; explained above.

60/E0*d 86E8 E46 ETS ONISN3311 WuS13nN PC 9T 666T-82-Wdu 3

1 Qu:stion 4 Rtsponsa, bullets following tha Nat:s -

> Added a bullet summarizing that a total of 3 tubes were left in s6rvice by P.

> Added sub-header clarifying that the remaining bullets are related to the implementation of the voltage-based repair criteria; updated these bullets per available data at end of outage; included the results of the retum-to-power Generic Letter g5-05 calculations.

Question 5 Response - Updated to reflect completion of plugging.

Question 7 Response - Updated to include discussion of the " Cold leg Freespan Other @ Ding" category.

Question 8 Response - Updated to include a summary of all pressure testing performed, with results.

Question 10 Response - Updated to reflect completion of the return-to-power preliminary Condition Monitoring Evaluation.

Question 11 Response-Updated to reflect completion of the retum-to-power preliminary Operational Assessment.

Question 12 Response - Updated to reflect current outage status.

Background Information - Added mention of upcoming steam generator replacement in Unit 1.

60/E0*d 9628 246 ETS DNISN331~1 Bu3 OnN PE:9T 666T-82-Ndu

I NRC PHONE DISCUSSION - 1RE08 STEAM GENERATOR TUBE INSPECTION RESULTS APRIL 1999 1.

Primary to Secondary leakage prior to shutdown.

STP 1RE08 - Leak rate during the just-completed Unit 1 Cycle 8 was a fraction of a gallon per day (see attached graph). Calculated leak rate with stable tritium concentration in the primary was less than 0.25 gpd during the first third of the cycle.

Over the final two-thirds of the cycle, there appears to have been a small increase in the leak rate to about 0.5 gpd. (Quantification of a change this small is uncertain since a change in the secondary make-up rate will change the primary-to-secondary tritium equilibrium and the make-up rate measurement is not very precise.) Higher leak rate values were calculated when the primary tritium concentration significantly decreased due to a down-power, but they are not valid since the primary and secondary tritiurn concentrations were no longer in equilibrium. We are confident the actual leak rate never exceeded a fraction of a gallon per day. Primary-to-secondary leakage integrity was very good right up to the end of the cycle.

2.

Results of secondary side hydro.

STP 1RE08 - STP does not routinely perform secondary side hydros during steam generator inspections. Eddy current testing of tubes and visual inspection of previously installed plugs are employed to ensure primary-to-secondary integrity, in this outage, all plugs were visually examined for signs ofleakage. No defective plugs were identified.

3.

For each SG, provide a general description of areas examined, include expansion criteria and specify type of probe used in each area.

STP 1RE08 -This was the third STP Unit 1 inspection where the voltage-based repair criteria was applied. Also, this was the first Unit 1 inspection where NEl 97-06 was formally implemented. The Inspection Plan was as follows:

100% bobbin full length (except for Row 1 & 2 U-bend).

100% H/L Top-of-tubesheet by RPC.

. ~43% C/L Top-of-tubasheet by RPC in SGs 1 A and 18 only.

Expansion Criteria: Inspect 100% in SGs with crack indications; 20% in SGs 1C &

1D. (No expansion was required.)

100% Row 1 & 2 (small radius) U-bend by + Point.

100% of freespan dings >5 volts by + Point.

100% of tubesheet region, full depth, for hot leg wavy tubes by RPC.

1 60/PO*d 86E8 E46 EIS ON!SN3311 hiu373nN PC:9I 6661-BE-hidu

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4.

For cn lyzed EC raaults, d:ecribs babbin indic tians (thoss net eximinzd with RPC) and RPC/Plus Point /Cecco indications. Include the following information:

location, number, degradation mode, disposition., and voltages / depths / lengths of the most significant Indications.

STP 1RE08 -The only bobbin indications not examined with RPC or + Point are as follows:

i DSis less than or equal to i volt (per voltage-based repair criteria)

MBMs that are unchanged from the baseline & Dings 5 volts and under (bobbin is qualified to detect axial indications through five volt dings).

AVB wear indications (Note that a 20% sample of AVB wear indications was examined by + Point. Note also that all Preheater wear indications were examined by

+ Point.)

Inspection results are as follows:

l PROBABLE DEGRADATION MODES FOR PLUGGED TUBES"0" PROBABLE DEG. MODE SG 1A SG 1B SG 1C SG 1D TOTAL H/L TTS Cire. ODSCC 1

3 16 4

24 H/L TTS & F* Distance Axial PWSCC 1

5 3

9 H/L TTS Volumetric 1

1 TSP ODSCC*'* 3 6

5 19 "' *

• 8 38 C/L Freespan Axial ODSCC @ Dino 2

2 7"'**

5 16 C/L Freespan Other @ Ding 2

1 3

C/L Freespan Volumetric 3

5 4 "" ' ' '

2 14 H/L Freespan Axial ODSCC @ Ding 1

1 H/L Freespan Volumetric 3

3 1

7 H/L PWSCC in Tubesht - Wavy Tubes 1

1 Loose Part Wear 0

TOTAL DEFECTIVE TUBES:

17 24 47 " '

24 112 "

Plugged at Rec. of Owner's Level lli 1

1 Permeability (preventive plug) 23 7

12 11 53 TOTAL PLUGGED:

41 31 59 35 166 H/L-Hot leg C/L-Cold leg TTS - Top-of-tubesheet expansion transition TSP-Tube Support Plate NOTE 1 - Plugging lists are complete.

NOTE 2 - Confirmed DSIs greater than one voit (APC lower voltage repair limit).

NOTE 3 - Deleted.

l NOTE 4 - One tube had DSis over one volt that were confirmed by RPC at two different support plates.

NOTE 5 -Two tubes in SG 1C had two freespan defects, one C/L Axial and one C/L Volumetric in each case.

No defects identified by the cold leg top-of-tubesheet RPC sample.

No defects identified in Row 1 & 2 U-bend examination.

Three tubes total left in service under F*; one each in SGs 1B,1C, & 1D.

l 2

60/S0*d 8628 E46 EIS ON!SN331"I Nt:G13nN SC29I 666T-82-NdW

Voltags-Bised R2piir Critaris inform tion:

~1268 tubes with DSI indications were left in service with bobbin voltage below the lower voltage repair limit (1.0 Volt). Final data to be provided in 90 day report.

One indication exceeded the upper voltage repair limit (4.0 Volts this inspection) and was plugged. (Bobbin voltage was 4.50 Volts and it did confirm.) When reviewed for analysis per Generic Letter 95-05, it was resized to 3.77 Volts. ~57 other indications exceeded the lower voltage repair limit, of which 39 indications (in 38 tubes) were confirmed by RPC and were plugged.

No PWSCC @ TSPs, no cire cracks @ TSPs, no axialindications extending outside the TSP were detected.

Conditional Burst Probability & End-of-Next-Cycle (EONC) Leakage calculations were completed per Generic Letter 95-05. The highest calculated End-of-Cycle 9 d

conditional burst probability was 2.0 x 10 in SG 1A, well below the limit of 1.0 x 10 2, The highest End-of-Cycle 9 SLB leak rate (room temperature) was 0.019 gpm in SG 1C, well below the limit of 15.4 gpm.

5.

Describe repair / plugging plans.

STP 1RE08 - All defects were plugged; no sleeving was performed this outage. See inspection Results Table above. Plugging is complete.

6.

Discuss previous history; "look backs" performed.

STP 1RE08 - Look backs performed on all freespan DNis (dings with possible flaw indications) & freespan NQls (non-quantifiable indications), to confirm no change from the baseline.

7.

Discuss new inspection findings.

STP 1RE08 - Circumferential indications at dings in freespan locations were identified for the first time at dTP (either unit) in this inspection. These indications were discussed in the phone call of 4/12/99. Two such indications had been identified at the time of the call.

During the phone call, the NRC recommended that STP base its conclusions on a 20%

sample of dings. STP adopted this recommendation, and further inspection was performed to achieve a 20% ding inspection. One additional circumferential indication was identified for a total of three. All three were pressure tested to the maximum pressure capacity of the test eo Sment (5000 psig), then re-examined by eddy current

(+ point). There was no leakt ;.4 during any of the pressure tests, and there was no apprent change in the post-pressure test eddy current signal. The circumferential sign als identified were as follows:

S ", C - R37C55 at ~14.2" below the top TSP on the cold leg side (11C)

!.:G C - R42C68 at ~6.6" below the top TSP on the cold leg side (11C) l SG D - R43C42 at ~2.1" below the top TSP on the cold leg side (11C) 1 3

E f)

Had the indicatlans represented circumfarantill cracks of significant siza, tha prassura exerted on the tube during the pressure test would have caused the crack to open up, and the eddy current signal would have been changed in the post-pressure test examination.

8.

Describe in situ pressure test plans and results, if available; include tube selection criteria.

STP 1RE08 - In-situ test plans / selection criteria were developed for all active and potential damage mechanisms prior to the outage. Also, during the outage, it was decided to pressure test all freespan circumferential indications to the maximum pressure capacity of the test rig. End cap loading was applied in all proof tests of circumferential indications, and in allleak tests.

The following pressure tests were conducted:

Cold leg freespan circumferential indications at dings:

> SG10, R42C68 -leak tested with no leakage; pressure proof tested with bladder to 5000 psig with no burst; post-test + point signal unchanged.

> SG10, R37C55 -leak tested with no leakage, pressure proof tested without bladder to 5000 psig with no burst; post-test + point signal unchanged.

> SG1D, R43C42-leak tested with no leakage, pressure proof tested without bladder to 5000 psig with no burst; post-test + point signal unchanged.

Circumferential OD indication at the hot leg roll transition:

> SG1C, R28C57-leak tested with no leakage; pressure proof tested with bladderwith no burst.

Axial OD cold leg freespan indications at dings:

> SG10, R40C74 -leak tested with no leakage; pressure proof tested with bladder with no burst.

> SG1C, R37C43 -leak tested with no leakage.

> SG1D, R22C15 -leak tested with no leakage.

> SG1D, R32C39 - leak tested with no leakage.

9.

Describe tube pull plans and preliminary results, if available; include tube selection criteria.

STP 1RE08 - No tubes pulled. (reference letter to NRC from Steve Thomas dated 8/18/98 - NOC-AE-000258) 10.

Assessment of tube integrity for previous operating cycle.

STP 1RE08 -Tube integrity requirements were maintained during the preceding cycle.

A preliminary evaluation against the NEl 97-06 performance criteria has been successfully completed. A final Condition Monitoring Assessment will be documented in the NEl 97-06 Tube Integrity Assessment Summary to be submitted following the outage.

4 60/40*d 96E8 E46 EiS DN!SN331"l WuS73nN SE:9I 666I-BE-Edu

11.

Acces2msnt cf tubs integrity for nsxt op2 rating cycis.

l STP 1RE08 - No conditions were found that would impede full cycle operation in Unit 1 l

Cycle 9 (287 Effective Full Power Days planned; 333 EFPD possible with coastdown). A preliminary evaluation against the NEl 97-06 performance criteria has been completed.

l The final Operational Assessment will be documented in the NEl 97-06 Tube Integrity Assessment Summary to be submitted following the outage. Also, the 90 day report required to support Generic Letter 95-05 commitments associated with the voltage-based repair criteria will be submitted within 90 days of breaker closure. (These two 90 day reports may or may not be combined.)

12.

Provide schedule for steam generator-related activities during remainder of current outage.

STP 1RE08 -

Data acquisition and analysis is complete.

Pressure testing is complete.

Plugging is complete.

=

Manways are installed.

Mode 4 entered on 4/27/99; breaker closure projected for 4/28/99 BACKGROUND INFORMATION ON STP UNIT 1:

Commercial Operation: 8/88 EFPY at 1RE08: 7.7 EFPY (Length of Cycle 8: 528 EFPD)

Model: Westinghouse Model E Tube Material: Alloy 600, mill annealed Tube Support Plates: Carbon Steel, with drilled holes Tubesheet expansion: full-depth hard roll.

That-3.93 EFPY at 623*F; 620"F since.

ID was roto-peened prior to commercial operation.

U-bend heat treatment of Rows 1 & 2 performed at first refueling outage.

Previous plugging history:

Tubes plugged prior to 1RE08:

1 A - 101 (2.1%)

1B - 91 (1.9%)

1C - 100 (2.1%)

1D - 119 (2.4%)

TOTAL: 411 (2.1%)

Steam Generator Replacement is scheduled at the end of Cycle 9.

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