ML20058M911
| ML20058M911 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 12/13/1993 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-93-003, IEB-93-3, NUDOCS 9312210154 | |
| Download: ML20058M911 (4) | |
Text
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NRCB No. 93-03 10CFR50.54(f) 1 PHILADELPHIA ELECTRIC COMPANY NUCLEAR GROUP HEADQUARTERS 955-65 CHESTERBROOK BLVD.
WAYNE, PA 19087-5691 (215) Mo4000 December 13, 1993 STATION SUPPORT DEPARTMENT License Nos. DPR-44 DPR-56 U.S. Nuclear Regulatory t,ommission Attn: Document Control Desk Washington, DC 20555
Subject:
Peach Bottom Atomic Puer Station, Units 2 and 3 Response to NRC Bulletin No. 93-03, " Resolution of Issues Relateu to Reactor Vessel Water Level Instrumentation in BWRs" Completion of Hardware Modifications Gentlemen:
HRC Bulletin No. 93-03 was issued on May 28, 1993, to notify P9111ng Water Reactor (BWR) licensees about new information concerning level indication errors that may occur during plant depres::71zation.
Specifi mlly, this Bulletin identified a concern that noncondensi' le gases may become dissolved in the reference legs of BWR reactor vessel wa: 9r level instrumentation and lead to a fMse high level indication followiag a reactor vessel depressurization. The NRC l
' o osted that BWR licensees take various short term compensatory actions to that potential level errors caused by reference leg de-gassing will not NHe 'n improper system response or improper operator actions during transients and accident scenarios initiated from reduced prusure conditions. In addition, l
the NRC requested that BWR licensees implement level instrumentation system j
hardware modifications at the first cold shutdown after July 30, 1993, to ensure that the level instrumentation system design is of high functional reliability i
for long-term operation.
i l
As stated in NRC Bulletin No. 93-03, " Reporting Requirement 3," a written report is required to be submitted to the NRC within 30 days of completion of requested hardware modifications, with a report confirming completion and describing the modification implemented.
By a letter dated July 30, 1993, we responded to Bulletin No. 93-03 and I
committed to provide a report confirming completion and describing the modifications within 30 days after the modifications have been installed at Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.
I 2000.L g4I 9312210154 931213
{DR ADOCK0500g7 g
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l This letter provides Philadelphia Electric Company's cenfirmaticn that modifications have been completed for PBAPS, Units 2 and 3.
The Unit 2 modifica' tion was completed on August 19, 1993.
The Unit 3 modification was completed on November 16, 1993. A summary of the modification installation is provided in the attachment.
This confirmation is being submitted under affirmation, and the required affidavit is enclosed.
If you have any questions or require additional information, please contact me.
l Very truly yours, fM Geor e
. Hunger, Director Licensing Section Enclosure Attachment j
cc:
T. T. Martin, Administrator, Region I,'USNRC l
W. L. Schmidt, Senior Resident Inspector, PBAPS g
I i
9 er COMMONWEALTH OF PENNSYLVANIA :
ss.
COUNTY OF CHESTER D. R. Helwig, being first duly ~ sworn, deposes and says:
That he is Vice President of Philadelphia Electric Company;. the Applicant herein; that he has read the attached Peach Bottom Atomic Power l
Station, Units 2 and 3 Response to NRC Bulletin No. 93-03, " Resolution of Issues Related to Reactor Vessel Water Level Instrumentation in BWRs"; Completion of Hardware Modifications for Peach Bottom Atomic Power Station Facility Operating '
License Nos. DPR-44 and DPR-56, and knows the contents _ thereof; and that. the statements and matters set forth therein are true and correct to the best.of his.
knowledge, information and belief.
i Vice Pres en Subscribed and sworn to before me this/
day o
1
-1993.
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Notary Public u/ SCI?s=yPsic%
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Nuclear R:gulat:ry Commissicn December 13, 1993 NRCB No. 93-03
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ATTACHMENT l
NRC BULLETIN NO. 93-03, " RESOLUTION OF ISSUES RELATED TO REACTOR VESSEL WATER LEVEL INSTRUNENTATION IN BWRs" Response to Reporting Requirement 3 i
A continuous backfill system to the cold reference legs associated with the Reactor Water Level Instrumentation was instalied in Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3.
The backfill system eliminates water in the reference leg that is saturated with non-condensible gases. The elimination of the gas laden water in the reference i,
leg will prevent the potential for the formation of gas bubbles, which would lead to unacceptable inaccuracies in the indicated reactor vessel levels during rapid depressurization events. The system also assures the correct level is maintained in the instrument condensing chamber in the event the chamber becomes gas bound and condensation : tops.
The water added to the reference leg flows back to the reactor vessel through the steam supply line to the instrument in the same manner as the current condensing chamber condensate does. The quantity of flow required to flush the reference leg column has been determined to be approximately 4 lba per hour. - This flow is sufficiently greater than the condensing rate of the condensing chamber and will assure the makeup will overcome potential instrument leakage. The nature of this flow is such that it is not required during accident conditions and there may be interruptions of or variations in flow without compromising the function. This results from the fact that the accumulation of gasses is prevented during normal operation.
r The source of water for the backfill system is the Control Rod Drive (CRD) System which is maintained at a pressure of about 1500 psig during normal operation.
Pipe and/or tubing is utilized for directing CRD flow to a common header at which point flow is diverted to each of the four reference legs associated with I
condensing chambers 2A, 2B, 3A, ivd 3B. Needle valves in the individual supply lines to each of four reference legs are utilized for flow control and flow indication is provided locally. Total backfill system flow as well as flow in 4
each of the individual reference leg supply lines is indicated.
Two check valves, in series, are provided to serve as a boundary between the non-safety related portion of the backfill system (i.e., that portion which connects to the non-safety related CRD System) and the safety related portion of the backfill system (i.e., that portion which connects to the reference leg of the safety related Reactor Instrumentation system). The flow control and indication devices are installed in the non-safety related section of the system.
In addition to the flow control and indication devices, the backfill system is proviled with manual valves and vents as required to facilitate system startup (i.e., fill), maintenance, testing, and surveillance activities.
The manual valves also provide a means for manually isolating all or part of the backfill system from the CRD and Reactor Instrumentation systems.
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