ML20151B694

Provides Addl Info Re MSIV Stroke Time Requirements,Per NRC 880303 Telcon Request to Assist in Review of 870727 Application for Amend to License NPF-3.Amend Would Revise Tech Specs 3/4.3.2,3/4.6.3 & 3/4.7.1

ML20151B694
Person / Time
Site:	Davis Besse
Issue date:	03/31/1988
From:	Shelton D TOLEDO EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
1501, TAC-65858, NUDOCS 8804110144
Download: ML20151B694 (9)

Text

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TOLEDO

%mm EDISON A Certeur Dww Creww Docket No. 50-346 DONALD C. SHELTON Vce Presdert Wehr License No. NPF-3 Serial No. 1501 March 31, 1988 United States Nuclear Regulatory Commission Document Control Desk Vashington, D.C.

20555 Subj ect :

Supplemental Information for the License Amendment Application to Revise the Main Steam Isolation Valve Stroke Time Requirements (TAC No. 65858)

Gentlemen:

In response to a request made during a March 3, 1988 conference call between Toledo Edison representatives, Mr. A. V. DeAgazio (Davis-Besse Project Manager, Nuclear Regulatory Commission (NRC)/Of fice of Nuclear Reactor Regulation (NRR)), and other members of the NRC Staff, Toledo Edison is providing additional information to assist in the review of the subject License Amendment Application dated July 27, 1987 (Serial No. 1387). This amendment would revise the Technical Specifications Sections 3/4.3.2, 3/4.6.3 and 3/4.7.1, closure time requirements for the Main Steam Isolation Valves (MSIVs).

Each of the NRC questions is listed belov, followed by Toledo Edison's response.

Question:

Provide a table of all Davis-Besse Safety Analysis Report (SAR) Chapter 15, Accident Analysis, events and list the MSIV stroke time assumed in the analysis.

Response

Toledo Edison has reviewed all SAR Chapter 15 accident analyses and has provided the requested information in.

Please note that the time for SFRCS response /

MSIV closure time shown under SAR Section 15.2.8 vill be revised to 6.5 seconds as described in our letter (Serial No.

1387).

Question:

The Safety Evaluation submitted with letter Serial No. 1387 stated that while a delay in closing the HSIVs "may affect the plant response during a feedvater line break, it has been demonstrated that the consequences of those changes are acceptable so that all design criteria are met, resulting in no change in the consequences of the event."

Provide a 3

summary of the analysis used to support this statement.

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i Docket No. 50-346 License No. NPF-3 Serial No. 1501 Page 2

Response

Toledo Edison has provided, in Attachment 2, a summary of calculation C-NSA-083.03-001, Revision 0, which evaluated a delayed MSIV closure time effect.

l Question:

What impact does the proposed Technical Specification change to the HSIV closure time requirements have upon the Safety Analysis Report Main Steam Line Break (MSLB) analyses?

Response

The proposed changes to the HSIV closure time requirements have no impact upon the SAR Chapter 15 MSLB analyses. The SAR Chapter 15.4.4, Steam Line Break, analysis assumes a 1 second response time for lov steam line pressure instrument detection and a 5 second time for HSIV closure. The HSIV closure is conservatively modeled as an instantaneous step closure at 5 seconds instead of a ramp closure over 5 seconds. The combined instrument response and valve closure time of 6 seconds is the basis for the present Steam and Feedvater Rupture Control System (SFRCS) response time requirement of 6 seconds specified in Technical Specification Table 3.3-13, Steam and Feedvater Rupture Control System Response Times.

Since the HSIV closure time for the lov Hain Steam line pressure SFRCS trip remains at 6 seconds in the proposed Technical Specification change being reviewed, there is no impact upon the Chapter 15 MSLB analyses.

The blowdovn data used in SAR Section 6.2, Containment Systems,forthecontainmentanalysisofthelimit{ngMSLBis presented in SAR Table 6.2-11, Data for the 5.4 ft Main Steam Line Break with 800 gpm Auxiliary Feedvater Flov to each Steam Generator (Notes using an Auxiliary Feedvater flovrate of 800 gpm yields conservative results when compared to lover Auxiliary Feedvater flow rates).

In this evaluation, credit was given for the closure of the turbine stop valves. This resulted in the isolation of the unaffected steam generator after two seconds. The existing non-return valves in the 36 inch main steam piping provide an alternate, passive means to terminate blovdown of the unaffected steam generator. The blovdown data from the unaffected steam generator vas conservatively calculated assuming no credit for frictional effects of the piping and the larger AFV flovrate.

In this evaluation the HSIV stroke time has no effect on the HSLB analysis results nresented in the Davis-Besse SAR Chapter 6, Engineered Safety Features.

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O Docket No. 50-346 License No. NPF-3 Serial No. 1501 Page 3 Question:

If no specific closure time is listed for the HSIVs, it is possible that other Technical Specification requirements for their stroke time may be overlooked. Vould it not be preferable to add a footnote to the Technical Specification which would refer the user to the other, more restrictive Technical Specification for HSIV closure time?

Response

Toledo Edison has evaluated this suggestion and has determined that it is preferable not to add an additional footnote. Providing a footnote which references another Technical Specification to Table 3.6-2, which already has four footnotes, vould add to operator burden and would be inconsistent with the current format of the Technical Specifications. Consequently Toledo Edison requests that the License Amendment be approved as originally proposed in Serial No. 1387.

Toledo Edison believes this letter responds to all NRC concerns regarding the License Amendment Application submitted by Serial No. 1387.

If you have any other questions, please contact R. V. Schrauder, Nuclear Licensing Manager, at (419) 249-2366.

Very tr y yours,

/4 + / b DRB/bam cc:

DB-1 NRC Resident Inspector A. B. Davis, Region III Regional Administrator A. V. DeAgazio, NRC/NRR Davis-Besse Project Manager n

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e Docket No. 50-346 License No. NPF-3 Serial No. 1501 Page 1 Davis-Besse SAR Accident Analyses Assumed MSIV Stroke Time Assumed Assumed Assumed Total MSIV SFAS Level 4 SFRCS Assumed Accident SAR Closure

Response

Response Time for Analysis Section Time Time

• Time

• SG Iso.

Uncontrolled 15.2.1 N/A N/A N/A N/A CRA Group Vithdrawal Vhile Suberitical Uncontrolled 15.2.2 N/A N/A N/A N/A CRA Group Vithdraval l

at Power CRA 15.2.3 N/A N/A N/A N/A Hisalignment Makeup and 15.2.4 N/A N/A N/A N/A Purification 1

System Halfunction Loss of Forced 15.2.5 N/A N/A N/A N/A Reactor Coolant System Flov Startup of an 15.2.6 N/A N/A N/A N/A Inactive Reactor i

Coolant Loop Loss of 15.2.7 N/A N/A N/A N/A External Electrical Load and/or Turbine Trip Loss of Normal 15.2.8 5 see N/A 1 sec 6.0 see Feedvater 1

• Time 0.0 is defined as the time the trip setpoint is reached.

Docket No. 50-346 License No. NPF-3 Serial No. 1501 l

Page 2 Total Assumed Assumed Assumed Assumed MSIV SFAS Level 4 SFRCS Time Accident SAR Closure

Response

Response for SG Analysis Section Time Time

• Time

• Iso.

Loss of all 15.2.9 Assumed N/A Assumed N/A AC Pover to to occur, to occur, the Station no specific no specific Auxiliaries time, MSIV time closure not important i

Excessive Heat 15.2.10 N/A N/A N/A N/A Removal Due to Feedvater System l

Malfunction l

Excessive 15.2.11 Bounded by N/A Bounded Bounded Load MSLB by MSLB by MSLB Increase analysis analysis analysis l

Anticipated 15.2.12 N/A N/A N/A N/A Variations in the Reactivity of j

the Reactor i

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Failure of 15.2.13 N/A N/A N/A N/A Regulating i

Instrumentation 4

f External 15.2.14 N/A N/A N/A N/A Causes l

Loss of 15.3.1 N/A N/A N/A N/A I

Reactor Coolant from i

Small Ruptured

(

Pipes...

f

• Time 0.0 is defined as the time the trip setpoint is reached.

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Docket No.10-346 License No. NPF-3 Serial No. 1501 Page 3 Total Assumed Assumed Assumed Assumed MSIV SFAS Level 4 SFRCS Time Accident SAR Closure

Response

Response for SG Analysis Section Time Time

• Time

• Iso.

Minor 15.3.2 N/A N/A N/A N/A Secondary System Pipe Breaks Inadvertent 15.3.3 N/A N/A N/A N/A Loading of a Fuel Assembly Into an Improper Position Vaste Gas 15.4.1 N/A N/A N/A N/A Decay Ta.nk i

Rupture 1

Steam 15.4.2 N/A N/A N/A N/A Generator Tube Rupture i

CRA Ejection 15.4.3 N/A N/A N/A N/A Steam Line 15.4.4 5 see N/A 1 sec 6 sec Break Pieak in 15.4.5 N/A N/A N/A N/A Instrument Lines or Lines From Primary Systems that Penetrate Containment

• Time 0.0 is defined as the time the trip setpoint is reached.

l Docket No. 50-346 License No. NPF-3 Serial No. 1501 l

Page 4 Total Assumed Assumed Assumed Assumed MSIV SFAS Level 4 SFRCS Time for Accident SAR Closure

Response

Response SG Analysis Section Time Time

• Time

• Iso.

Major Rupture 15.4.6

<60 see 1 see N/A

<60 see of Pipes for Containing containment Reactor isolation Coolant only, not for accident mitigation (from Chapter 6 6.2.4.2.1)

Fuel Handling 15.4.7 N/A N/A N/A N/A Accident Effects of 15.4.8 N/A N/A N/A N/A Toxic Material Release on the Control Room

• Time 0.0 is defined as the time the trip setpoint is reached.

Docket No. 50-346 License No. NPF-3 Serial No. 1501 Page 1 Summary of Davis-Besse Calculation C-NSA-083.03-001:

SFRCS Response Time Following a Feedvater Line Break A.

Assumptions made in calculation 1.

A high reverse differential pressure Steam and Feedvater Rupture Control System (SFRCS) Trip occurs within 1.0 second following a mair. feedvater line break (MFVLB).

2.

No credit is taken for Turbine Stop Valves or Non-Return Valve isolation of the unaffected Steam Generator.

3.

The mass flow out the break is proportional to the area of the break. This allows the Main Steam Line brgak blovdown data presented in SAR Table 6.2-31 for a 5.4 ft steam line break to be scaled for use in this analysis to estimate additional blovdown for a MFVLB.

4.

Blovdown from the break is saturated steam.

5.

Allowing the HSIV to stay open for gn additional 1.5 seconds contributes an additional 2.31 x 10 BTU and 2000 lbm of steam to containment.

6.

Air is an ideal gas.

7.

Theinitialcontainmenttemperatureis120*gandcontainment is at 14.7 psia.

Containment volume is 2.83 x 10 cubic feet.

8.

The peak containment pressure is coincident with the peak containment temperature.

B.

Analysis of Containment Environment following a Feedvater Line Break a) Hethod 1.

Determine the additional amount of extra mass and energy being added to containment as a result of the increased MSIV closure time of 6.5 seconds.

2.

Instantaneously add this additional mass and energy to the containment at the time the peak containment pressure of 12.9 psig for a MFVLB occurs.

Docket No. 50-346 License No NPF-3 Serial No.

Page 2 3.

Use the lav of partial pressures of gases, the ideal gas law for air, and conservation of mass and energy for air and steam to determine the instantaneous increase in containment pressure and temperature.

4.

Compare the calculated containment pressure and temperature to the containment design basis values and containment transient response due to other design basis events such as LOCAs and MSLBs.

b) Results 1.

The new calculated peak containment pressure is 14.1 psig versus 12.9 psig presented in the SAR.

2.

The calculated increase in containment temperature is 7'F higher than predicted in previous analyses.

Conservatively adding this increase directly to the peak temperature for the MFVLB causes the peak to increase to 250'F.

3.

As expected, these values are much less than the values predicted for a LOCA or a MSLB, but slightly greater than the previous MFVLB analyses.

C.

Conclusion It is concluded that requiring the MSIV's to be closed 6.5 seconds following a high reverse differential pressure trip of SFRCS due to a HFVLB does not create a significant increase in peak containment 1

pressure and temperature conditions. The HFVLB does not replace LOCAs as the limiting event for containment design.

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