ML17265A312

Provides More Detailed Description of Basis for Proposed Setpoint Language Contained in 970929 Application for Amend, Per 980428,0513 & 20 & 0603 Telcons W/Nrc Re Change to Main Steam Isolation Setpoint.Revised TS Pages Encl

ML17265A312
Person / Time
Site:	Ginna
Issue date:	06/04/1998
From:	Mecredy R ROCHESTER GAS & ELECTRIC CORP.
To:	Vissing G NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17265A313	List: ML17265A312 ML17265A315
References
NUDOCS 9806100264
Download: ML17265A312 (15)

Text

CATEGORY 1 REGULATE INFORMATION DISTRIBUTIOh SYSTEM (RIDS)

ACCESSION NBR:9806100264 'OC.DATE: 98/06/04 NOTARIZED: YES DOCKET ¹ FACIL:50-244" Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION MECREDY,R.C. Rochester Gas 8 Electric Corp.

RECIP.NAME RECIPIENT AFFILIATION VISSING, G. S .

SUBJECT:

Provides more detailed description of basis for proposed setpoint language contained in 970929 application for amend, per 980428,0513 R 20 R 0603 telcons w/NRC re change to main steam isolation setpoint.Revised TS pages encl.

DISTRIBUTION CODE: A001D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: OR Submittal: General Distribution E

NOTES:License Exp date in accordance with 10CFR2,2 .109(9/19/72) . 05000244 G

RECIPIENT COPIES RECIPIENT COPIES 0 ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD1-1 LA 1 1 PD1-1 PD 1 1 VISSING,G. 1 1 INTERNAL: ILE CE 01 1 1 NRR/DE/ECGB/A 1 1 DE/EMCB 1 1 NRR/DRCH/HICB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 NUDOCS-ABSTRACT 1 1 OGC/HDS3 1 0 EXTE NOAC 1 1 NRC PDR 1 1 D

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N NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 TOTAL NUMBER OF COPIES REQUIRED: LTTR 13 ENCL 12

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C3 AND ROCHESTER GAS AND ELECTRIC CORPORATION ~ 89 EASTAVENLIE, ROCHESTER, N. Y 14649-000I ARFA CODE716 546-270O ROBERT C. MECREDY Vice President Nvdeor Operotions June 4, 1998 U.S. Nuclear Regulatory Commission Document Control Desk Attn: Guy S. Vissing Project Directorate I-1 Washington, D.C. 20555

Subject:

Main Steam Isolation Setpoint License Amendment Request Rochester Gas & Electric Corporation R.E. Ginna Nuclear Power Plant Docket No. 50-244

Reference:

(a) Letter from.R.C. Mecredy, RG&E, to G.S. Vissing, NRC,

Subject:

Application for Amendment to I"acili(yOperating License, Change to Main Steam Isolation Setpoint (LCO Table 3.3.2-l, Function 4.d), dated September 29, 1997.

(b) Conference calls of April 28, May 13 and 20, and June 3, 1998 between RG&E and NRC.

Dear Mr. Vissing In Reference (a), RG&E submitted a proposed change to the Improved Technical Specification (ITS) setpoint for main steam isolation (Table 3.3.2-1, Function 4.d). Recently, RG&E and the NRC discussed the language being proposed for the revised setpoint and why this differed from Standard ITS (Reference (b)). The purpose of this letter is to describe in more detail the basis for the proposed setpoint language and to revise the proposed ITS bases to provide further clarification.

The following table illustrates the differences between the RG&E proposed changes to ITS Table 3.3.2-1, Function D and those in Standard ITS:

~GG d Standard ITS Allowable Value s 0.66E6 ibm/hr 1005 psig s [25%] of full steam flow at no load steam pressure Trip Setpoint s 0.4E6 ibm/hr 1005 psig s [] of full steam fiow at no load steam pressure (s-'lA~P, .

9806i00264 05000244 980604'DR ADOCK P PDR

As can be seen, the primary differences are: (1) use of a specific flowrate versus a percentage of full steam flow,.and (2) use of a specific pressure versus "no load steam pressure." These differences are discussed in detail below.

I Attachment I provides a simplified figure of one of the four main steam flow instrument loops. As can be seen on this figure, FT-464 is a differential pressure transmitter whose signal is sent to three functions. The first signal goes to main control board indicator FI-464 after being compensated by main steam pressure (PM-464A) and processed by a square root extractor (FM-464B) and a repeater (FM-464C). The second signal goes to an alarm (FC-464A) and then to two bistables for the high steam flow and high-high steam flow functions listed in ITS Table 3.3.2-1, Function 4. The third and last signal goes to a repeater (FM-464D) and to the advanced digital feedwater control system (ADFCS).

The only output signal from FT-464 which is pressure compensated is that for the main control board indication. The output signal to the high and high-high steam flow bistables via alarm FC-464A is a direct value from the differential pressure transmitter. However, the bistable trip setpoints do have a pressure compensation "adjustment". That is, the bistable trip setpoint matches the ITS specified conditions of 0.4E6 Ibm/hr N 1005 psig. This is accomplished by identifying the required signal to main control board indicator FI-464 for steam line flow/pressure conditions of 0.4E6 Ibm/hr 1005 psig. This signal value is traced back through the logic shown in Attachment I (repeater, square root extractor, and steam pressure multiplier) to identify the required output of the differential pressure transmitter for FT-464. This calculated output signal from the differential pressure transmitter is what is used for the bistable setpoint; hence, the pressure compensation "adjustment". Attachment II provides additional details.

As described above, the bistable setpoints are based on a specific set of plant steam flow and pressure conditions. Consequently, the Ginna Station ITS must specify these plant conditions versus the Standard ITS terms of"% full steam flow" and "no load steam pressure" even though the Ginna specified conditions are essentially equivalent to the Standard ITS terms. The accident analysis also uses these same plant conditions. That is, for those analyzed steam line breaks requiring automatic steam line isolation, the accident analysis assumes a main steam isolation signal is generated immediately aiba a safety injection setpoint is reached. The analysis is then reviewed afterwards to ensure that the remaining coincident main steam isolation parameters listed in ITS Table 3.3.2-1 are also met. For the case of small steam line breaks, the accident analysis verifies that the main steam flow is >0.66E6 Ibm/hr with pressure s 1005 psig prior to reaching safety injection setpoints. Higher steam flowrates or lower pressures would generate a higher differential pressure across the flow transmitter ensuring that the bistable setpoint is reached. Since normal full power conditions result in steam flows and pressures of approximately 3.3 ibm/hr and 730 psig respectively, the bistables for ITS Table 3.3.2-1, Function 4.d are normally tripped.

Therefore, the use of a specific flowrate and pressure remains consistent with the accident analysis and reflects that the bistable setpoint does not automatically change ifsteam conditions were to change. As such, the Ginna Station ITS is different from Standard ITS in implementation, but not in intent.

The bases originally submitted in Reference (a) are revised in Attachment 3 to provide this additional discussion. This replaces in its entirety, the bases provided in Attachment II to Reference (a). In addition, based on discussions during the June 3, 1998 conference call, an issue was identified with respect to the presentation style of ITS Table 3.3.2-1. Specifically, the Trip Setpoint column of this table is actually a nominal setpoint value (with tolerance bands) while the Allowable Value column is the analytical value used in the accident analysis. While consistent with the Ginna Station Setpoint Analysis, it does not provide a clear operability setpoint. In order to provide this clarification, RG&E is reevaluating the format and specific content of ITS Table 3.3.2-1 for inclusion in a future License Amendment Request.

Very yours, Robert C. Mecredy Subscribed and sworn to before me on this+ day of June i998.

5 Notary Public MARIE C. VILI.ENEUYE Notary Public, State of New York Monroe County Commission Expires October 31, 19 MDF/100 Attachments xc: U.S. Nuclear Regulatory Commission Mr. Guy S. Vissing (Mail Stop 14B2)

PWR Project Directorate I-1 Washington, DC 20555 U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Ginna Senior Resident Inspector

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Attachment I Block Diagram of Steam Flow Transmitter Instrument Loop FT-464

4.0 Block Diagram and Scope of Analysis Ref; Precalculation Instrument Review Checklist Block Diagram for Steam Generator Instrument Loop F464.

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" DEVICE DVTfVTIS HOT WITHN THE SCOPE OF AHALYSIS MAINSTEAMF464 BLOCK DIAGRAM SHEET I MSF464.(TWG Figure 1 EWR 5126 Design Analysis DA EE-92-089-21 Page 11 of 52 Revision ~

Attachment II Pressure Compensation Evaluation

Rochester Gas and Electric Corporation Inter-Office Correspondence May 5, 1997

SUBJECT:

Hi and Hi-Hi Steam Flow Setpoints for Steamline Isolation Logic TO: Mark Flaherty Nuclear Safety and Licensing The instrument bistables which provide the Hi and Hi-Hi Steam Flow trip functions for Main Steam Isolation do not receive a steam pressure compensation. signal, however, the setpoints have been appropriately calculated and set to account for the required steam pressures specified in the Ginna Technical Specifications.

The Hi-Hi steam flow bistable is set to trip at,a steam flow differential pressure (DP) of 861.2 inwc which corresponds to the DP associated with a main steam flow of 3.6 MPPH at 755 psig (i.e. full load conditions) as required by. the Technical Specifications. Refer to the attached block diagram for an overview of the methodology used to determine the appropriate setpoints. Similar methodology using 0.4 MPPH steam flow and 1005 psig S/G pressure is used to determine the compensated Hi Steam Flow bistable trip setpoint.

Richard A. Baker Technical Support Nuclear Engineering Services Attachment

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Attachment III Revised Bases