ML20080U138

Provides Confirmation That Requested Level Instrumentation Sys Hardware Mods Completed,In Response to NRC Bulletin 93-003,Reporting Requirement 3.Summary of Mod Installation Encl

ML20080U138
Person / Time
Site:	Limerick
Issue date:	03/07/1995
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 9503140245
Download: ML20080U138 (4)

Text

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.h s Etation support Department w .

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? NRCB No. 9343 10CFR50.54(f) .

March 7,1995 Docket Nos. 50-352 y 50-353 License Nos. NPF-30 -- -i NPF-85 j i

U.S. Nuclear Regulatory Commission .i Attn: Document Control Desk ,

Washington, DC 20555 1

. i Subject. Limerick Generating Station, Units 1 and 2

"::;-:-,66 to NRC Bulletin No. 93-03, " Resolution of issues Related to Reactor Vessel Water Level Instrumentation in BWRs* . ,

Completion of Hardware Modifications -l Gentlemen: 3

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.NRC Bulletin No. 9343 was issued on May 28,1993, to notify Bolling Water Reactor (BWR) i licensees about new information concoming level indication errors that may occur during plant _ j depressurization. Specifically, this Bulletin identified a concem that noncondensible gases may become dissolved in the reference legs of BWR reactor vessel water level instrumentation and ,

lead to a falso high level indication following a reactor vessel depressurization. The NRC requested that BWR licensees take various short term compensatory actions to ensure that :l potential level errors caused by reference leg de-gassing will not result in improper system l response or improper operator actions during transients and accident scenarios initiated from reduced pressure conditions. In addition, the NRC requested that BWR licensees implement  ;

level instrumentation system hardware modifications at'the first cold shutdown after July 30, 1993, to ensure that the level instrumentation system design is of high functional reliablity for . .i long-term operation.  ;

=i As stated in NRC Bulletin No. 93-03, ' Reporting Requirement 3," a written report is required to be j submitted to the NRC within 30 days of completion of rayW hardware modifications, with a i report ec.,b,#,g completion and describing the modification impiamented. j i

By letter dated July 30,1993, we roeponded to Bulletin No. 9343 and committed to provios a - .[

report confirming completion and describing the modifications within 30 days after the .j modifications have been installed at both Limerick Generating Station (LGS), Units 1 and 2.  !

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9503140245'950307  ?

PDR- ADOCK 05000352 -

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., March 7,1996 Page 2 of 2 This letter provides PECO Energy Company's confirmation that modifications have been completed for LGS, Units 1 and 2. The Unit 1 modification was completed on September 9, 1993. The Unit 2 modification was completed on March 3,1995. Completion dates are based on acceptance of the Modification Acceptance Testing results. A summary of the modification installation is provided in the attachment.

This coiiTuisetion is being submitted under affirmation, and the required affidavit is enclosed if you have any questions or require additional infonnation, please do not hesitate to contact us.

Very truly yours, o

George A. Hunger, Jr.

Director - Licensing Attachment l cc: T. T. Martin, Administrator, Region 1. USNRC N. S. Perry, Senior Resident inspector, LGS i-1

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' COMMONWEALTH OF PENNSYLVANIA  :

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COUNTY OF CHESTER  : ,

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W. H. Smith, Ill, being first duly swom, deposes and says:

That he is Vice President of PECO Energy Company, the Applicant herein; that he has read the attached Limerick Generating Station, Units 1 and 2, Response to NRC Bulletin No.

9343, " Resolution of lasues Related to Reactor Vessel Water Level Instrumentation'in BWRs' invoMng completion of Hardwars Modifications for Limerick Generating Station, Faclity Operating License Nos. NPF-39 and NPF-85, 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.

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Vice President Subscribed and om to before me this day of 1995.

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Notary Public Nota 111 Seal Bica A Sarnort retaryPttic My  ? E h 995

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c^3 C et l' March 7,1996  ;

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> ATTACHMENTJ , k

- NRC BULLETIN NO. 9343, " RESOLUTION OF ISSUES REl.ATED  :

TO REACTOR VESSEL WATER LEVEL INSTRUMENTATION IN BWRs" Response to Reporting Requirement 3 -

A continuous backfil system to the cold reference legs amarvhad with the Reactor Water Level '  ;

. , instrumentation has boon installed in Limerick Generating Station (LGS), Units 1 and 2.~ .!

The backfill system eliminates water in the reference leg that is saturated wkh. nonendensible gases. The elimination of the gas leden water in the reference leg wBl prevent the potential for the j formation of gas bubbles,'which could lead to unacceptable inaccuracles in the indicated reactor z 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 stops.

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The water added to the reference leg Rows back to the reactor vessel through the steam supply line ' H to the instrument in the same manner as the current condensing chamber _ condensate. The quantky  :

of flow required to flush the reference leg column has been determined to be approximately 4 lbm per hour. This flow is sufficiendy greater than the condensing rate of the condensing chamber and .  ;

wNi assure the makeup wlN overcome potentialinstrument leakage. The nature of this flow is such, i 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 gases -  ;

is prevented during normal operation.'  ;

The source of water for the backfRI system is the Control Rod Drive (CRD) System which is l maintained at a pressure of about 1500 psig during normal operation Pipe and/ortubing is utlized . :i for directing CRD flow to a common header at which point Row is diverted to each of the four' l reference legs associated with condensing chambers Noodle valves in the individual supply lines 1 i

to each of four reference legs are utlized for flow control, and Sow indication is provided locally.

Total backful system flow as well as flow in each of the individual reference leg supply lines is indicated.

l Two clwek 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 backful 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 backftl_ system is provided with manual valves and vents as required to facultate system startup (i.e., fill), maintenance, testing, and  :

surveillance activities. The manual valves also provide a means for manually isolating aH or part of the backful system from the CRD and Reactor instrumentation systems.

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