ML20058C591
| ML20058C591 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 11/18/1993 |
| From: | Saccomando D COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9312020501 | |
| Download: ML20058C591 (4) | |
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j' h Commonw:alth Edison
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J4 / Dc;wners Grcue Enres 60515 1400 opus Place
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%J November 18, 1993 Dr. Thcmas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 s
Attn:
Document Control Desk Subject-Supplement to Request for EMERGENCY TECHNICAL SPECIFICATION AMENDMENT Facility Operation Licenses NPF-72 and NPF-77 Technical Specification Section 4.4.5.0 NRC Docket Nos. 50-456 and 50-457
References:
1)
D. M.
Saccomando letter to T.
Murley dated November 12, 1993, transmitting Commonwealth Edison's request for an EMERGENCY TECHNICAL SPECIFICATION AMENDMENT pertaining to Braidwood Unit 1 Steam Generator Outage 2)
Teleconierence between Commonwealth Edison Company (CECO) and the Nuclear Regulatory Commission (HRC) on November 16, 1993; Re: EMERGENCY TECHNICAL SPECIFICATION 1.MENDMENT Dear Dr Murley:
The referenced letter transmitted by Commonwealth Edison (CECO) proposed an amendment to Appendix A, Technical Specifications of Facility Operating Licenses NPF 72 and HPF 77.
The proposed amendment requested changes to Technical Specification Section 4.4.5.0.
Per the referenced teleconference, CECO is providing this supplement to clarify the information provided in the amendment request.
Specifically, Attachment A contains additional information regarding: the analysis method all dispositioning of the distorted tube support plate signals; and, why analysis of the Unit 1 C Steam Generator quantifiable indications does not suggest a tube integrity concern for the remaining Unit 1 steam generators.
CECO is notifying the Stato of Illinois of this supplement to the amendment request by transmitting a copy of this letter and the associated attachments to the designated State Official.
O R D O '"
9312O20501 931010 PDR ADOCK 05000456 NOp(
P PDR 88:
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Dr.
T. E. Murley 2
November 18, 1993 To the best of my knowledge and belief, the statements contained in this document are true and correct.
In some respects these statements are not based on my personal knowledge, but on information furnished by other CECO employees, contractor employees, and/or consultants.
Such information has been reviewed in accordance with company practice, and I believe it to be reliable.
Please address any further comments or questions regarding this matter to this office.
Respectfully, i
t'Ofv/-
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Denise M.
Saccomando Nuclear Licensing Administrator l
Attachment i
cc:
R.
R. Assa, Braidwood Project Manager - NRR S. G. Dupont, Senior Resident Inspector - Braidwood B. Clayton, Branch Chief - Region III
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Office of Nuclear Facility Safety - IDNS i
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Afogel% /f, /99T OFFICIAL SEAL MARYELLEN D LONG
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NOT ARY Ft%1C, STATE Of 11Lt4OIS MY COMM'SSION LXPRES:0941/97
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ATTACHMENT A HUMMARY The Novenber, 1993 Braidwood Unit 1 Steam Generator outage was l
prompted by a tube leak in the "C" Steam Generator.
CECO performed a detailed review of hist orical tube support plate eddy current data to determine if expansion of eddy current inspections was warranted in the other steam generators. The tube i
support plate indication growth rates identified for the Unit 1 i
"C" Steam Generator between the 3rd refueling outage and the current unplanned outage were compared with those observed for all Unit 1 steam generators between the 2nd and 3rd refueling outages.
In addition, the absolute values of the voltages identified during this unplanned outage were compared with that from previous outages.
The indication growth rate and the absolute value of the indications were found to be consistent with the values observed from the previous inspection period.
Further, the scheduled inservico inspection for the Unit 1 Steam Generators is only three and one-half months away.
Based on this analysis, CECO believes that inspection expansion into the other Unit 1 Steam Generators was not warranted, that tubes with distorted indications in the 1C Steam Generator did not need-to be plugged, and that a high level of confidence in all steam generator tube integrity exists.
The paragraphs below provide additional technical details to further substantiate this position, j
1.
Data analysis method and indication data Voltage measurement calibration, as required by the Commonwealth Edison Company (CECO) Data Analysis Guidelines, consists of I
setting the ASME 20% Flat Bottom Ho'les (FBH) signal to 4. volts peak-to-peak in Channel 1 and save/ store to all other channels l
and mixes.
This method is consistent with industry standard j
practices in the United States.
i Data for distorted indications and those assigned a percent through-wall were_ compared to raw data from the previous outage.
For this combined population in the Unit 1 "C"
an average voltage growth rate of less than 0.55 volts was observed since our last Unit 1 outage 13 months ago. This is considerably less than the average growth rate of 0.90 volts observed for all Braidwood Unit 1 steam generators between the second and third refuel outages (approximately a 17 month j
duration).
During this recent outage, the average voltage growth i
rate for distorted indications alone was less than 0.35 volts with none showing voltage growth greater than 1.35 volts.
For indications classified as 2 40% through-wall the average growth i
rate was less than 1.10 volts with none greater than 4.0 volts.
All voltage growth rates during this recent outage are consistent 1
with historical data trended at Braidwood and confirms the effectiveness of the CECO degradation predictions.
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Attachment A Page 2 Furthermore, indication voltages (absolute value, not growth rate) observed during this outage are also cons'istent with those observed during the previous Unit 1 outage.
For all distorted i
indications and percent through-wall calls in the Unit 1 "C"
steam generator the average indication' voltage was less than 1.00 volt, with none in excess of 4.75 volts.
The average voltage for distorted indications was less than 0.75 volts with none greater than 2.0 volts.
For indications classified as 2 40% through-wall t
average indication voltage was less than 1.60 volts, with none in excess of 4.75 volts.
t 2.
Further explanation of the basis for not expanding I
inspections into the other three Unit 1 steam generators during this unplanned outage.
i Historically, the Unit 1 "C"
Steam Generator has exhibited the s
greatest amount of tube degradation.
During the previous refuel outage the Unit 3 "C"
Steam Generator showed the highest percentage of indications and indication growth rate as compared to the other three steam generators.
It contained 47 percent of the total population of tubes plugged during that refuel outage.
This number is nearly double the percentage of total. tubes plugged in the steam generator showing the second highest amount of degradation The growth rate in the other three steam generators since the last refuel outage is expected to be less i
than that recently measured in the Unit 1 "C"
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