ML17309A627
| ML17309A627 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 02/06/1998 |
| From: | Mecredy R ROCHESTER GAS & ELECTRIC CORP. |
| To: | Vissing G NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17265A155 | List: |
| References | |
| NUDOCS 9802120041 | |
| Download: ML17309A627 (7) | |
Text
CATEGORY 1 REGULA Y INFORMATION DISTRIBUTIOA SYSTEM (RIDS)
ACCESSION NBR:9802120041 DOC.DATE: 98/02/06 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
&, Electric Corp.
RECIP.NAME RECIPIENT AFFILIATION VISSING,G.S.
SUBJECT:
Forwards response to request for addi info re util 970929 request for amend to license DPR-18,revising TS on main steam line isolation signal set point. Design analysis DA EE-92-089-21,Rev 1 encl.
DTSTRTBUTTON CODE:
A001D COPTES RECETVED:LTR 3 ENCL i
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TITLE: OR Submittal: General Distribution 9Z, NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72) 05000244 G
RECIPIENT ID CODE/NAME PD1-1 LA VISSING,G.
COPIES RECIPIENT LTTR ENCL ID CODE/NAME 1
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INTERNAL ILE CENTRE 01 EMCB NRR/DSSA/SPLB NUDOCS-ABSTRACT 1
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E NOTE TO ALL "RIDS" RECIPIENTS:
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AND ROCHES7ER GASANDELEC7RkC CORPORA77ON
~ 89 FAS7 AtrrENUE, ROCHESTER, N. Y 1dbf9-0001 ARFA CODE716 54'6-27O0 ROBERT C. MECREDY Vice President Nudeor Operations February/1 998 U.S. Nuclear Regulatory Commission Document Control Desk Attn:
Guy S. Vissing Project Directorate I-1 Washington, D.C. 20555
Subject:
Response to Request for Additional Information dated November 20, 1997 Rochester Gas &Electric Corporation R.E. Ginna Nuclear Power Plant Docket No. 50-244
Reference:
Letter from Guy S. Vissing, NRC, to R.C. Mecredy, RG&E, Request forAdditional Infornration - Review ofthe Request for Aknendhnent Dated Septekkkber 29, 1997-Change to the Technical Specificatiokk related to the Main Steakn Line Isolation Sigkkal Set Poikkts (TACNo. M99702), dated November 20, 1997
Dear Mr. Vissing,
Enclosed please find a response to the subject request for additional information (RAI). Please contact us ifwe may be any further assistance.
Very trul yours, Dy Robert C. Mecredy Subscribe/ and sworn to before me on thisP'th day ofFebruary 1998.
b Notary.Public 30HM-SCOTT FlSH Notary Public in the State of Nee York Monroe Coun My Commission Expires 01FI5008 155 MDF858 Attachment
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7 The response to Questions 1 through 4 have been consolidated into one response.
Provide the bases forFuzzction 4.d, "High Steanz Flow Coincident with Safety Injection and Coincident with T
- Lo>v, "and Function 4.e, "High - High Steam Flow Coincident with Safety Injection" ofLCO Table 3.3.2-I. Provide a discussion ofhow the bases for these fiznctions willbe met with the proposed Allowable Values and Trip Setpoints forModes I, 2, azzd 3.
Provide a discussion of the applicable analyses and how these fzznctions are modeled.
Provide the setpoints used in the analysis.
Izzyour submittal you stated,
"...Function 4.e willnot provide closure ofthe MSIVs due to an inadvertent opening of azz atmospheric relief or safety valve.
Consequezztly, only Fuzzction 4 dperforms thisfirzzctiozz. " However, the setpoint forFunction 4.d is higher than the capaci ty ofa single atmospheric reliefvalve. Please explain your statement.
Yozz stated, "Choosing I0% RTP equat'es to 0.66I'6 lbnzfhr and is also equal to two ARVs opening at I005psig. " However, should both ARVs open, the steazn generators would blow dow)zfz'ozzz each of the ARVs and, therefore, each steam line would ozzly be expected to expe'rience the effect ofa single open ARV. Also, the proposed allowable value would require a steanz break to reszzltin aflow eqzzivalent to the capacity oftwo ARVs (ozz a steanz line) before the Allowable Value is'reached.
Justify your selection ofthe allowable value for breaks resulting inflows ranging betweezz the proposed value and the sizes assuznedin UFSAR Section I5.I.6.
The steam line break analyses for Ginna Station are described in UFSAR Sections 6.2.1.2, 15.1.5, and 15.1.6. A discussion ofthe Chapter 15 analyses with respect to LCO Table 3.3.2-1 is provided below.
Steam line breaks for the containment integrity analysis (UFSAR Section 6.2.1.2) occur upstream ofthe main steam isolation valves (MSIVs) such that the non-return check valves are credited with preventing blowdown from more than one steam generator.
The non-return check valves are passive devices that are not assumed to fail; therefore, automatic isolation via the MSIVs is not assumed (see ITS bases page B 3.7-7).
Adiscussion ofthe Chapter 15 analyses with respect to LCO Table 3.3.2-1 is provided below.
UFSAR Section 15.1.5 provides the assumptions and results ofsteam line breaks equivalent to: (1) a fullseverance ofa main steam line, and (2) a steam release through one main steam safety valve (MSSV). Although only hot zero power conditions are presented in the UFSAR, other power levels (e.g., 30%, 70%, 100%) have been evaluated to demonstrate that hot zero power is most limitingwith respect to DNB. The LOFTRAN code is used for steam line break analyses.
Main steam isolation is required for both UFSAR Section 15.1.5 cases with the MSIVs assumed to close within 5 seconds of receiving a close signal.
This 5 second closing time is addressed by ITS surveillance requirement SR 3.7.2.1.
The generation ofthe closing signal is described below:
For the large steam line break scenario, credit is taken for main steam isolation on high-high steam flow coincident with SI (i.e., LCO Table 3.3.2-1, Function 4.e).
Specifically, the MSIVs are assumed to receive a closure signal 2 seconds after the SI parameter for low steam line pressure is reached (358 psig per LCO Table 3.3.2-1, Function l.e). This is due to the fact that the high-high steam flow input of3.7E6 ibm/hr is reached very rapidly (<<
1 second) with SI on low steam line pressure
'ccurring at approximately 1.5 seconds (see UFSAR Table 15.1-6). The fact that the SI occurs~ the high-high steam flowinput is also verified after the LOFTRANrun is complete.
The additional 2 second delay addresses signal delay time after the SI parameter has been met.
For the steam release equivalent to a MSSV lift, credit is taken for main steam isolation on high steam flowcoincident with SI and low T(i.e., LCO Table 3.3.2-1, Function 4.d).
Similar to the large steam line break, the MSIVs are assumed to receive a closure signal 2 seconds after the SI parameter is reached.
The high steam flowinput of0.66E6 ibm/hr (i.e., proposed Allowable Value) is reached very rapidly since the flowrate through a MSSV is 0.82E6 ibm/hr per UFSAR Table 10.1-1 (also see UFSAR Figure 15.1-34).
The low T, of543'F is reached approximately 40-50 seconds after the break per UFSAR Figure 15.1-33.
The SI occurs after 100 seconds (see UFSAR Table 15.1-6) with an additional 2 second time delay assumed.
The fact that the SI occurs affer the high steam flowand low T~ input is also verified after the LOFTRANrun is complete.
UFSAR Section 15.1.6 describes the assumptions and results ofthe combined atmospheric reliefvalve (ARV) and main feedwater regulating valve (MFRV) failures. These combined failures are addressed due to postulated instrument failures with respect to the advanced digital feedwater control system (ADFCS). Several cases were examined (see Table 15.1-7) with the worst being the coincident failure ofboth ARVs and both MFRVs going full open.
Each ARVprovides flowequivalent to 0.329E6 ibm/hr per UFSAR Table 10.1-1. As stated in UFSAR Section 15.1.6.1.2, manual operator action to initiate SI, feedwater isolation, and main steam isolation is assumed to occur at 600 seconds for hot zero power cases (i.e., ug automatic main steam isolation is assumed).
For full power cases, a reactor trip terminates the event either automatically or manually at 600 seconds (i.e.,
~n automatic main steam isolation is assumed).
Given these assumptions, the full steam line breaks at hot zero power remain bounding.
In summary, Ginna Station has analyzed and documented in the UFSAR steam line breaks down to that equivalent to a MSSV steam release (0.82E6 lbm/hr) assuming automatic steam line isolation.
In addition, steam line breaks up to the flow equivalent to two ARVs (or 0.66E6 Ibm/hr) have been analyzed assuming no steam line isolation until 600 seconds.
However, this steam flow is divided between two steam generators.
This is not considered to be significant since the overall cooldown effect on the RCS would be the same.
Also, the UFSAR analysis assumes that both MFW regulating valves failed full open to maximize the cooldown effect. This assumption is not valid for a steam break equivalent to 0.66E6 lbm/hr on one steam generator since ADFCS could not cause a break size this large. RGB has performed a LOFTRAN run with a 0.66E6 lbm/hr break in one steam generator with no steam line isolation until 600 seconds with MFW operating normally. For this case, the coincident ARV and MFW regulating valve failure remains bounding.
Therefore, RGkE has selected 0.66E6 lbm/hr as the Allowable Value for the LCO Table 3.3.2-1, Function 4.d since there is no existing UFSAR analysis demonstrating that manual steam line isolation is acceptable above this flowrate. The basis for the Trip Setpoint of0.4E6 lbm/hr is addressed in response to Question 5 below.
Provide theinslnunent uncertainty calculation that was performed to confirtn the Allowable Value willnot be exceeded.
Discuss the analytical value usedin this calculation.
A copy of Design Analysis EE-92-089-21, Revision 1 is attached.
Section 10.0 of this analysis presents the actual setpoint evaluation based on the instrument loop uncertainties calculated in earlier sections ofthe analysis.
As shown on the bottom ofpage 48, a setpoint of 0.4E6 Ibm/hr did not meet the current Allowable Value of 0.55E6 lbm/hr when all uncertainties were accounted for.
Attachment 1 (page 52) shows that with a revised uncertainty analysis for this instrument loop based on Ginna historical data, and using the existing setpoint of0.4E6 Ibm/hr, the new Allowable Value of0.66E6 lb/hr would be met.