ML20207D878

Rev 1 to EMF-98-015, Millstone Unit 2 Loss of Normal FW Flow Transient with Reduced Auxiliary FW Flow

ML20207D878
Person / Time
Site:	Millstone
Issue date:	12/08/1998
From:	SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER
To:
Shared Package
ML20207D861	List: B17670, Forwards Response to NRC 990202 RAI to Aid in Review of Proposed License Amend Request Re Loss of Normal FW Flow. Copy of Siemens Lonf Analysis for Millstone Unit 2,which Is Ref in Attachment 1 Is Contained in Attachment 2 ML20207D878
References
EMF-98-015, EMF-98-015-R01, EMF-98-15, EMF-98-15-R1, NUDOCS 9903100092
Download: ML20207D878 (120)

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SIEMEN5 EMF-98-015 i

Revision 1 Millstone Unit 2 Loss of Normal Feedwater Flow Transient With Reduced Auxiliary Feedwater Flow l

l December 1998

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9903100092 990301 7

PDR ADOCK 05000336 p

PDR j

l Siemens Power Corporation Nuclear Division

I ISSUEDINSPC ND ON.UNg DOCUMERrSYSTEM Siemens Power Corporation - Nuclear Division D* M 4 /98

'dMF-98-015 Revision 1 Millstone Unit 2 Loss of Normal Feedwater Flow Transient With Reduced tuviliary Feedwater Flow

/2-T'N Prepared:

B. D. Stitt, Tesin Leader Date PWR Safety Analysis Contributor:

P. R. Boylan Touch Base Computing, Inc.

Lawrenceville, GA.

Approved:

k. d.

! !9S I

I2.f R. C. Gottula, Manager Date

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PWR Safety Analysis l

Concurred:

/2/I/f 7

'. S. Holm '

Da'te Regulatory Affairs Concurred:

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8 L. E. Hansan, M$ lager Date Customer Projects l

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Customer Disclaimer Important Notice Regarding Contents and Use of This Document i

Pilnese Rond CarefuRy i

Siemens Power Corporation's warranties and representations concerning the subject matter of this document are those set i

forth in the agreement between Siemens Power Corporation and t

the Customer pursuant to which this document is issued.

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agreement, neither Siemens Power Corporation nor any person i

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makes any warranty or representation, express or l

implied, with' respect to the accuracy, completeness, or f

usefulness of the information contained in this document, or that the use of any information, apparatus, method or process disclosed in this document will not mfringe privately owned rights; or i

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The information contained herein is for the sole use of the f

Customer.

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acceptance of this document, agrees not to publish or make

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expressly provided in the Agreement.' No rights or heenses in or to any patents are implied by the furnishing of this document.

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Nature of Changes i

Paragraph item or Page(s)

Description and Justification 1.

Sec 2.1 Added results for Main Steam Dumps Enabled case: Qualified Cases 1-4 to be for MSSV secondary heat sink only.

2.

Section 3 Added methodology description for Case 5 analysis.

3.

Table 4.1

' Added initial conditions for Case 5 analysis 4.

Table 4.2

'Added setpoints and analysis bases used for Case 5 analysis 5.

Section 5.5 Added new Section describing results of Case 5 analysis (Main Steam Dumps enabled) 6.

Table 5.5 Added sequence of events for Case 5 analysis 7.

Figs. 5 65 -

Added plots for Case 5 analysis i

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Millst:n3 Unit 2 Lass cf N:rrnal FeIdwatIt Fisw Transient Revision 1 With Reduced Auxiliary Feedwater Flow Pageli l

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Contents t

1.

I n t r od u ctio n.................................................................

2.

Su m mary of K e y Re s uits.................................,...........................................

2.1 FSAR Chapter 14 Analysis...................

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d et h od o lo g y De se rip tio n........................................................................I

.1 F S AR C h a pte r 14 Analy sis.................................................................... 3-1 4.

Initial Conditions and Analysis Bases................................................................ 4-1 4.1 FS AR Ch a pte r 14 Analysis.................................................................... 4 1 i

5.

A n a l y si s R e s u lt s..................................................................................

5.1 FSAR Chapter 14 Loss of Normal Feedwater With Offsite Power Available, Steam-Driven AFW Pump Fails............................................... 5-1 5.2 FSAR Chapter 14 Loss of Normal Feedwater With Offsite Power Available, One Motor-Driven AFW Pump Fails....................................... 5-20 5.3 FSAR Chapter 14 Loss of Normal Feedwater With Loss of Offsite Power, Steam-Driven AFW Pump Fails................................................. 5-39 5.4 FSAR Chapter 14 Loss of Normal Feedwater With Loss of Offsite Power, One Motor-Driven AFW Pump Fails........................................... 5-58 5.5

FSAR Chapter 14 Loss of Normal Feedwater With Offsite Power Available, One Motor Driven AFW Pump Fails, Steam Dumps Enabled..... 5 77 6.

References....................................................................................................6-1 Tables 4.1 Plant Initial Conditions for FSAR Chapter 14 LNFF Analysis with Reduced A u x ilia ry F e e d w a t e r Fl o w............................................................................... 4-2 4.2 - Analysis Bases For FSAR Chapter 14 LNFF Analysis with Reduced Auxiliary FeedwaterFlow............................................................................................43 l

l 5.1 Sequence of Events for FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start............................................ 5-3 5.2 Sequence of Events for FSAR Chapter 14 Analysis with Offsite Power Available, One Motor-Driven AFW Pump Fails to Start.................................... 5 22 3

5.3 Sequence of Events for FSAR Chapter 14 with Loss of Offsite Power, Steam-Driven AFW Pump Fails to Start......................................................... 5-41 1

Siemens Power Corporation Nuclear Division

U EMF-98-015 Millstona Unit 2 Less of Normd Fudwatzr Fisw TrcnsiInt Rsvizien 1 With Reduced Auxiliary Feedwater Flow Page iii 5.4 Sequence of Events for FSAR Chapter 14 with Loss of Offsite Power, One Motor-Driven AFW Pump Fails to Start................................................... 5-60 5.5 Sequence of Events for FSAR Chapter 14 LNFF Analysis with Offsite Power Available, One Motor Driven AFW Pump Fails to Start, Steam '

D u m p s E n a bled........................................................................................... 5 - 7 Figures

-5.1 Reactor Power, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start........................................................... 5-4 5.2 RCS Loop Temperatures, FSAR Chapter 14 Analysis with Offsite Power Available, Steam Driven AFW Pump Fails to Start............................................ 5 5 5.3 Pressurizer Pressure, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start........................................................... 5-6 5.4 Pressurizer Level, FSAR Chapter 14 Analysis with Offsite Power Available, Steam Driven AFW Pump Fails to Start........................................................... 5-7 5.5 Pressurizer Spray Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam Driven AFW Pump Fails to Start........................................................... 5-8 5.6 Pressurizer PORV Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam Driven AFW Pump Fails to Start........................................................... 5 9 5.7 RCS Charging Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pu mp Fails to Start......................................................... 5-10 5.8 RCS Loop Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start......................................................... 5-1 1 5.9 SG Dome Pressure, FSAR Chapter 14 Analysis with Offsite Power Available, Steam Driven AFW Pu mp Fails to Start......................................................... 5 12

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5.10 SG Main Steam Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-13 5,'11 SG Narrow Range Level, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-14 5.12 SG Liquid Mass inventory, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start..................................,....... 5-15 Siemens Power Corporation - Nuclear Division

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5.13 SG Collapsed Liquid Level, FSAR Chapter 14 Analysis with Offsite Power l

Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-16 5.14 SG Auxiliary Feedwater Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-17 5.15 SG Blowdown Flow, FSAR Chapter 14 Analysis with Offsite Power Available,

' Stea m.D rive n A FW Pu mp F ails to Sta rt......................................................... 5-18 l

5.16 SG Thermal Power, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-D riven A FW Pu m p Fails t o Sta rt......................................................... 5-19 i

5.17 Reactor Power, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start.................................................... 5 23 I

5.18 RCS Loop Temperatures, FSAR Chapter 14 Analysis with Offsite Power I

Available, "B" Motor Driven AFW Pump Fails to Start..................................... 5-24 5.19 Pressurizer Pressure, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start.................................................... 5 25 j

5.20 Pressurizer Level, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start.................................................... 5-26 5.21 Pressurizer Spray Flow, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5 2 7 5.22 Pressurizer PORV Flow, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start.................................... 5-28 5.23 RCS Charging Flow, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Sta rt.................................................... 5-29 5.24 RCS Loop Flow, FSAR Chapter 14 Analysis with Offsite Power Available, i

"B" Moto r-D rive n AFW Pu mp Fails t o St a rt.................................................... 5-3 0 5.25 SG Dome Pressure, FSAR Chapter 14 Analysis with Offsite Power Available, i

"B" Mot or-Drive n AFW Pu mp Fails to Sta rt.................................................... 5 31 I

.5.26. SG Main Steam Flow, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start.................................................... 5-3 2 5.27 SG Narrow Range Level, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-33 Siemens Power Corporation Nucleer Division

EMF-98-015 Millst:n3 Unit 2 Less of N:rm:I Fe:dwat:r H:w Tr:nsi:nt Rzvisi:n 1 With Reduced Auxiliary Feedwater Flow Page v 5.28 SG Liquid Mass Inventory, FSAR Chapter 14 Analysis with Offsite Power i

Available, "B" Motor Driven AFW Pump Fails to Start..................................... 5-34 5.29 SG Collapsed Liquid Level, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-35 5.30 SG Auxiliary Feedwater Flow, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-36 5.31 SG Blowdown Flow, FSAR Chapter 14 Analysis with Offsite Power Available, "B " M ot or D riven A FW Pu m p Fa ils to St a rt.................................................... 5 -3 7 5.32 SG Thermal Power, FSAR Chapter 14 Analysis with Offsite Power Available, "B" M otor-D riven A FW Pu m p Fails t o Sta rt.................................................... 5-3 8 5.33 Reactor Power, FSAR Chapter 14 Analysis without Offsite Power Available, St ea m-D rive n A FW Pu mp Fails t o S t a rt......................................................... 5 4 2 5.34 RCS Loop Temperatures, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-43 5.35 Pressurizer Pressure, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-44 5.36 Pressurizer Level, FSAR Chapter 14 Analysis without Offsite Power Available, St e a m-D rive n AFW Pu m p Fail s to St a rt......................................................... 5-4 5 5.37 Pressurizer Spray Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-46 5.38 Pressurizer PORV Flow, FSAR Chapter 14 Analysis without Offsite Power l

i Available, Steam-Driven AFW Pump Fails to Start........................................ 5-47 l

5.39 RCS Charging Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-48 i

5.40 RCS Loop Flow, FSAR Chapter 14 Analysis without Offsite Power Available, i

St e a m D rive n AFW Pu m p Fail s t o Sta rt...................................................... 5-4 9 5.41 SG Dom s Pressure, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-50 5.42 SG Main Steam Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-51 Siemens Power Corporation - Nuclear Division

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EMF-98-015 Millst:ne Unit 2 Loss cf Norm;l Fredwat:r Flow Trcnstnt R;visi:n 1 With Reduced Auxiliary Feedwater Flow Page vi 5.43 SG Narrow Range Level, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-D.-!ven AFW Pump Fails to Start.......................................... 5-52 5.44 SG Liquid Mass inventory, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5 53

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5.45 SG Collapsed Liquio Level, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-54 5.46 SG Auxiliary Feedwater Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start................................ 5-55 5.47 SG Blowdown Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-56 5.48 SG Thermal Power, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start.......................................... 5-57 5.49 Reactor Power, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Sta rt.................................................... 5-61 i

l 5.50 RCS Loop Temperatures, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-62 5.51 Pressurizer Pressure, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-63 1

1 5.52 Pressurizer Level, FSAR Chapter 14 Analysis without Offsite Power Available, l

"B" Motor-Driven AFW Pump Fails to Sta rt.................................................... 5-64 5.53 Pressurizer Spray Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-65 5.54 Pressurizer PORV Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-66 5.55 RCS Cnarging Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-67 5.56 RCS Loop Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Mot or-D rive n AFW Pu m p Fails to Sta rt.................................................... 5-6 8 5.57 SG Dome Pressure, FSAH Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-69 5.58 SG Main Steam Flow, FSAF. Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-70 Siemens Power Corporation - Nuclear Division

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EMF-98-015 Millst:n3 Unit 2 Less cf N:rm:l F;edwat:r Fisw Transient RIvisiin 1 With Reduced Auxiliary Feedwater Flow Page vii 5.59 SG Narrow Range Level, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-71 5.60 SG Liquid Mass inventory, FSAR Chapter 14 Analysis without Offsite Power

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Available, "B" Motor Driven AFW Pump Fails to Start.................................... 5-72 5.61 SG Collapsed Liquid Level, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-73 5.62 SG Auxiliary Feedwater Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start........................... 5-74 i

5.63 SG Blowdown Flow, FSAR Chapter 14 Analysis without Offsite Power Avauable, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-75 5.64 SG Thermal Power, FSAR Chapter 14 Analysis without Offsite Pow 2r Available, ~B" Motor-Driven AFW Pump Fails to Start..................................... 5-76 5.65 Reactor Power, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start.................................................... 5-80 5.66 RCS Loop Temperatures, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start..................................... 5-81 5.67 Pressurizer Pressure, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled... 5-82 5.68 Pressurizer Level, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled... 5-83 5.69 RCS Charging Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps EnabMd.................. 5-84 5.70 RCS Loop Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled.................. 5-85

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5.71 SG Dome Pressure, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled... 5-86 5.72 SG Main Steam Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled.................. 5-87 5.73 SG Narrow Range Level, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start, Steam Dumps Enabled... 5-88 Siemens Power Corporation - Nuclear Division

EMF.98-015 Millst:na Unit 2 L:ss of N:rmal Feedw t:r Flow Tr:nsiint Revision 1 With Reduced Auxiliary Feedwater Flow Page viii

. 5.74 SG Liquid Mass inventory, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start Steam D u m p s E n a b l e d..............................................................

5.75 SG Collapsed Liquid Level, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam DumpsEnabled...........................................................................................5-90 5.76 SG Auxiliary Feedwater Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Stearn D u m p s E n a b l e d..............................................................................

5.77 SG Blowdown Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled... 5 92

. 5.78 SG Thermal Power, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled... 5 93 l

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EMF 98-015 Millstone Unit 2 L:ss cf Norm:1 FredwatIr Fl2w Trcnsi:nt Revision 1 i

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Introduction This report presents the results of a re-analysis of the Loss of Normal Feedwater Flow (LNFF) event for Northeast Utilities System Millstone Unit 2 Nuclear Power Station. The revised analysis provides an FSAR Chapter 14 Section 14.2.7 Loss of Normal Feedwater Flow transient analysis that incorporates reduced Auxiliary Feedwater (AFW) system flow rates consistent with 5% degraded AFW pump capacity.

f The analysis was conducted to demonstrate that the Auxiliary Feedwater (AFW) System

-design is adequate to remove decay heat, prevent Steam Generator (SG) liquid dryout, maintain Reactor Coolant System (RCS) subcooling, and prevent pressurizer level from exceeding aoceptable limits. The prevention of SG dryout is a plant specific licensing requirement per Reference 4,'Section 2.5.4, " Loss of Feedwater Flow Event." The analysis conservatively models SG blowdown untilit is automatically isolated after AFW t

j system actuation, and an allowance for purging hot feedwater from the affected portion of 1

l the Main Feedwater piping is included.

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Summary of Key Results '

2.1 FSAM Chapter 14 Anaksis Five transient cases'were analyzed.' Each case was analyzed using 102% power, maximum allowed positive reactivity feedback, and maximum permitted pressurizer level.

The initiating event for each case is an instantaneous loss of main feedwater. Cases 1

-i and 2 verify acceptable AFW system performance when offsite power is available' and the Reactor Coolant Pumps (RCPs)' maintain forced coolant' flow through the primary system and the Main Steam. Safety Valves (MSSVs) are credited as the sole post-trip secondary heat sink. Cases 3 and 4 verify accepte.Lh /.?W system performance when offsite power-is assumed to be lost coincident with the reactor trip, and ' primary to secondary heat

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i transfer is achieved via natural circulation. Case 5 verifies acceptable' AFW system performance'when offsite power is available and the Main Steam Dump System is utilized j

for secondary steam relief and RCS temperature control.

The first case (Section 5.1) considers an active failure of the ~ steam-driven AFW pump.

I The'second case (Section 5.2) assumes an active failure of one of the two motor-driven AFW pumps, but the steam-driven AFW pump is available. The third and fourth cases

'(Sections 5.3 and 5.4) are a repetition of the first two cases except that offsite power is assumed to be lost at the time of reactor trip. Case 5 examines the short term tradeoff between additional secondary inventory boiloff due to steam dump temperature control versus increased AFW flow due to lower SG pressures. Thus, Case 5 repeats the single motor-driven AFW pump _ failure scenario of Case 2, but enables the steam dump system

. and applies zero pe ~ent SG tube plugging to minimize post-trip SG liquid inventories.

. Eliminating SG tubi olugging produces slightly higher SG pressures and lower AFW flows for transient scenaric s where SG pressure is controlled by the steam dumps instead of by the MSSVs. Case 5 utilizes a SG low level reactor trip analytical setpoint of 43% narrow range, while Cases 1-4 apply the previous Technical Specification analytical limit of 34%.

.The results of these cases demonstrate that the AFW system capacity and associated reactor trip and AFW system actuation setpoints at Millstone Unit 2 are adequate to maintain primary to secondary heat transfer such that the plant can be stabilized and brought to safe shutdown in a controlled manner. A minimum SG inventory is maintained

.throughout each case and the pressurizer (PZR) steam space is preserved. Analysis Cases Siemens Power Corporation - Nuclear Division.

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3 and 4 generated the highest PZR levels. The maximum pressurizer level was 76.3%,

which is an increase of only 4.3% above the initial pressurizer level of 72% and is well below the point at which the pressurizer experiences a liquid solid condition. For Cases 1 through 4 (steam dumps disabled), the minimum SG inventory occurred for Cases 1 and 2, with minimum SG liquid mass inventories of 3,347 lbm and 1,140 lbm per SG, i

respectively. SG liquid mass inventories remained well above 14,000 lbm per SG for both of the natural circulation cases (3 and 4). RCS subcooling margin was maintained at all times in each case.

i Case 5 demonstrates that a higher SG level reactor trip setpoint is required to preclude SG dryout when the steam dumps are enabled. The minimum SG liquid inventory for Case 5 is 5,540 lbm per SG when the reactor trip analytical setpoint has been increased to 43%

narrow range SG level. The +9% diffe oce in the SG level reactor trip setpoint from the other cases results in Case 5 being the bounding scenario for minimum SG inventory, despite the fact that Cases 1 and 2 produce a lower minimum liquid mass value.

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Methodology Description The methodology (Reference 1) used to perform the following analyses utilized the ANF-

.i RELAP computer code.' ANF-RELAP is a code which simulates the behavior of multi-loop i

pressurized water reactors subjected to abnormal operating conditions, such as loss of feedwater, turbine trip, flow coast down, control rod drop, et. The model is based on the solution of the transient two-phase conservation equations (mass, energy,'and momentum)

.j for the primary and secondary coolant systems, of the transient heat conduction equations for the fuel rods, and of the point kinetics equation for the core neutronics.

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The LNFF event is classified as an ANS Condition ll event, Faults of Moderate Frequency.

These faults may result in a reactor trip, with the plant capable of being returned to normal

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operation. The LNFF event is further classified by the NRC Standard Review Plan (NUREG-

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0800, Section 15.2.7), as a Decrease in Heat Removal by the Secondary System.

1 The Standard Review Plan lists the following acceptance criteria for Condition 11 events:

1.

Pressure in the Reactor Coolant System (RCS) and main steam system should be maintained below 110%'of the design values.

2.

Fuel cladding integrity should be maintained by ensuring that the minimum DNBR remains above the 95/95 DNBR limit.

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- An incident of moderate frequency should not generate a more serious plant condition without other faults occurring independently.

4.

An incident of moderate frequency in combination with any single active component failure, or single operator error, shall be considered and is an.

t event for which an estimate of the number of potential fuel failures shall be provided for radiological dose calculations. For such accidents, fuel failure must be assumed for all rods for which DNBR falls below those values cited above for cladding integrity unless it can be shown, based on an acceptable fuel damage model, that fewer failures occur. There shall be no loss of function of any fission product barrier other than the fuel cladding.

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Instrument spans and setpoints are used with regard to their impact on the plant response to the type of transient.

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The most limiting type plant systems single failure shall be identified and assumed in the analysis.

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l There are two other Category ll events which always produce a lower DNBR than the LNFF event. The Loss of Electrical Load (LOEL) event bounds the LNFF event for minimum f

DNBR, because in the LOEL event a significant RCS heatup occurs prior to reactor trip. In the LNFF event, the heatup prior to reactor scram is relatively small. The Loss of Coolant i

Flow event bounds the LNFF event with loss of offsite power assumptions. In the Loss of I

Coolant Flow analysis, the RCPs are tripped as the initiating event. Reactor trip occurs on j

low coolant flow, and the core flow rate at the time of trip is significantly lower than in the j

LNFF analysis where the RCPs are tripped coincident with the reactor trip. The core power to flow r*+8a is much higher for the Loss of Coolant Flow event, thereby producing a more

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limiting minimum DNBR. Since the LNFF event has been determined not to be a limiting l

event with regard to minimum DNBR, acceptance criteria 2 and 4 (noted above) will not be i

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If it can be demonstrated that the pressurizer does not fill solid during the LNFF event, the LOEL analysis is also the bounding event for RCS pressurization (acceptance criteria 1).

The biases applied in the LOEL analysis ensure that RCS pressure is maximized. The rapid

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pre-trip heatup associated with the LOEL event causes significantly higher primary system pressure than the slower developing LNFF scenario, j

t Therefore, the LNFF event can be conservatively analyzed for compliance with acceptance criteria 3! 5, and 6 by focusing on two transient-specific criteria.

1.

Avoidance of pressurizer overfill and associated liquid discharge through the l

pressurizer safety valves (which can result in a more serious plant condition l

and can also be considered a loss of a fission product barrier other than the fuel cladding), and 2.

Maintenance of a minimum secondary side liquid inventory to prevent development of a more serious plant condition (loss of RCS subcooling margin) if steam generator dryout occurs for an extended period.

At least two separate cases are required to ensure compliance with the above criteria.

5 The principal uncertainty is the affect of RCP trip on the transient results. If the RCPs remain on, the pump heat isnposes a significant heat load on the system. If the RCPs are tripped, primary to secondary heat removal capability is degraded due to natural i

circulation.

f I

l Siemens Power Corporation Nuclear Division t

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EMF-98-015 Millstona Unit 21. css cf Normil F7edwater Flow Transient Revision 1 i

With Reduced Auxiliary Feedwater Flow Page 3-3 A further uncertainty is the potential effect of the steam dump system on short term SG i

inventory. Enabling the steam dumps has the potential to exacerbate SG dryout as the dump system actuates to cool the RCS to no-load temperature after trip, if a failure scenario or plant configuration exists which provides only very minimal AFW flow for the j

first few minutes of the event. This is because the minimum recorded SG levelis the result of a balance between the increased condensate boiloff required to cool the RCS to 1

no load temperature, versus the increased AFW flow associated with lower SG pressures.

The assumed initial failure of one of the two motor-driven AFW pumps makes this initial minimum AFW flow scenario applicable to Millstone Unit 2 because of the required 10 minute delay assumption for manual start of the steam driven AFW pump. Thus the failure of a single motor-driven AFW pump is analyzed both with and without the steam dumps enabled to ensure that the plant-specific no SG dryout criterion is satisfied.

The Millstone Unit 2 AFW system consists of two independent motor-driven pumps which are designed to start automatically within 240 seconds of AFW system actuation on low-low SG level. There is also a double capacity steam-driven AFW pump which is started by operator action. (The operator action may be credited 10 minutes following reactor trip in the safety analysis.) The piping configuration allows each pump to supply both SGs simultaneously. There are two potential single active failures in this configuration: One is the failure of the steam-driven AFW pump to start, and the other is the failure of one of the two motor driven AFW pumps to start. Because of the differences in pump capacity and actuation times, it is not immediately obvious which single active failure is the most limiting.

The loss of offsite power option (RCP trip), combined with the two single active failure possibilities produce a total of four base cases. These four cases collectively demonstrate compliance with both the pressurizer overfill criterion and the SG secondary water inventory criterion when the MSSVs are the sole secondary heat sink. The biases and initial conditions for the cases are identical and are selected to maximize pressurizer level increase and to minimize SG level recovery. The question of steam dump operation adds a fifth t,cse which determines whether the SG inventory boiloff required to cool the RCS to no-load temperature is offset by increased AFW flow at lower SG pressures.

The LNFF event is analyzed from full power (plus uncertainty) conditions. This is the bounding case for initial power level. The full power initial condition maximizes the core decay heat that must be removed in the post-scram period. A primary concern in l

Siemens Power Corporation Nuclear Division

l EMF-98-015 Millstrn) Unit 2 Less cf Norm:I Facdwit:r Flow Tr nsiInt Revision 1 With Reduced Auxiliary Feedwater Flow Page 3-4 simulating this event is to demonstrate adequate long-term cooling capability. The single active failure assumptions reduce heat removal capacity by significantly limiting the amount of AFW flow supplied to the steam generators.

The analysis is reported in three parts. The first part (Sections 5.1 and 5.2) considers the cases where offsite power is available. The second part (Sections 5.3 & 5.4) considers the cases where offsite power is lost at the time of the reactor trip on low SG wate: level.

i Section 5.5 reports the results of Case 5, which examines the effect of enabling the steam cumps on the minimum SG level scenario (Case 2) from the previous four base cases.

Case 5 shows that the flow from a single motor-driven pump is not enough to completely offset the condensate boiloff due to RCS cooldown to no-load temperature. Level does not recover until the steam-driven AFW pump is started. However, the increased flow at lower SG pressure from two motor driven AFW pumps (base Case 1) is fully adequate to offset the SG inventory loss due to use of the steam dumps and cooldown to no-load temperature. Since the minimum SG level calculated for Case 5 will be lower than for any i

of the other base case scenarios with steam dumps enabled, the Case 5 scenario produces the bounding minimum SG level for the current AFW system configuration at Millstone Unit 2.

l l

i 1

Siemens Power Corporation - Nucleer Division i

y-EMF-98-015 Millst::n3 Unit 2 Less of Normal F:cdw:ter F12w Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 4-1 4.

Initial Conditions and Analysis Bases 4.1 FSAR Chapter 14 Analysis Table 4.1 lists the initial conditions for the steady state ANF-RELAP model. These are the plant conditions immediately preceding the LNFF initiating event.

Table 4.2 describes the assumptions regarding setpoint biases and enabled / disabled plant syst;ms.

The plant auxiliary system inputs which affect the LNFF analysis were supplied by Northeast Utilities System in References 2 and 3.

t l

l l

l Siemens Power Corporation - Nuclear Division

EMF-98-015 Millst:na Unit 2 Loss of Norm:I Fa:dwatIr Flow Trcnsi nt Revision 1 f

With Reduced Auxiliary Feedwater Flow Page 4-2 Table 4.1 Plant initial Conditions for FSAR Chapter 14 LNFF Analysis with Reduced Auxiliary Feedwater Flow Parameter Value Core Power 2754 MWt Core inlet Temperature 549*F Pressurizer Pressure 2250 psia i

Pressurizer Liquid Level 72%

i Reactor Vessel Flow Rate 360,000 gpm Moderator Temperature Coefficient

+ 4.0 PCM/ F Doppler Coefficient (includes 0.8 multiplier)

-0.92 PCM/*F Steam Generator Pressure i

Cases 1-4 (5% SG tube plugging) 829 psia

(

Cace 5 (0% SG plugging) 846 psia Steam Generator Liquid Level 70% Narrow Range Steam Generator Secondary Mass inventory

=141,000 lbm Main Steam Flow 12.0 x 10 lbm/hr 5

Main Feedwater Temperature 435 F Steam Generator Blowdown Flow 300 gpm Auxiliary Feedwater Temperature 100*F t

d Siemens Power Corporation - Nuclear Division

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EMF-98-015 Millston] Unit 2 Less cf Norm::1 F:odwater Flow Transient Revision 1 j

With Fleduced Auxiliary Feedwater Flo.s Page 4-3 i

Table 4.2 Analysis Bases For FSAR Chapter 14 LNFF Analysis with Reduced Auxiliary Feedwater Flow

{

1.

Initiatino Event: Instantaneous loss of all main feedwater 2.

,RPS Trip Setpoint:

i Cases 1-4 (SG pressure controlled by MSSVs):

34% of Narrow Range SG level. This value includes all necessary uncertainties, and is required to meet the analysis acceptance criterion of no SG dryout when the MSSVs are the sole secondary heat sink.

Case 5 (SG pressure controlled by Steam Dumps):

43% of Narrow Range SG level. This value includes all necessary j

uncertainties, and is required to meet the analysis acceptance criterion of no SG dryout when the Condenser Steam Dumps or Atmospheric Dump Valves j

are enabled, i

3.

AFW Actuation Trip Setpoint: 10% of Narrow Range SG level, (also termed " low-low SG level"). This value includes all necessary uncertainties, and is required to meet the analysis acceptance criterion of no SG dryout.

3 l

4.

Span of Narrow Ranoe SG Level: 181.6 in. The reference elevation for 0.0%

narrow range level is 302.4 inches above the top of the tube sheet.

5.

Primary System Pressure Control: The PORV and pressurizer spray system are l

enabled and function at nominal setpoints so as to promote insurge into the pressurizer, thereby maximizing pressurizer level. This is conservative with respect to the pressurizer level acceptance criterion. The pressurizer safety valves are enabled but are inconsequential because they are not challenged by this event when the pressurizer spray system and PORV are enabled.

i 6.

RCS Heat Structures: The ANF-RELAP model conservatively includes passive RCS heat structures (vessel and pipe walls). Although not required by methodology (Reference 1), the passive heat structures add to the overall conservatism by increasing the sensible heat which must be removed from the primary system.

7.

Secondary System Pressure Control:

Cases 1-4:

The steam dump system (atmospheric dump and condenser bypass valves) are disabled. The Main Steam Safety Valves (MSSVs) are enabled and set to open at the nominal setpoints plus 3% tolerance. MSSV blowdown is 6%

from the biased opening setpoints.

Siemens Power Corporation Nuclear Division

EMF 98-015 Millstons Unit 2 Less of N2rm:I Fssdw;t:r Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 4-4 i

The trip logic used in the ANF-RELAP model applied in Cases 1-4 does not account for the dynamic pressure term which accompanies active steam flow through the safety valves. Neglecting the dynamic pressure term is conservative for the Loss of Normal Feedwater analysis. Were this term to be included, the effective MSSV blowdown would be larger than 6%, and consequently, the average SG pressure would be less. The reduction in average SG pressure would permit additional AFW flow compared to the existing analysis.

f Case 5 The steam dump system (atmospheric dump and condenser bypass valves) are enabled. The Main Steam Safety Valves (MSSVs) are enabled but are not challenged after reactor / turbine trip due to the action of the steam dump system.

8.

Reactor Coolant Pump Operation: All four RCPs remain on for Cases 1, 2, and 5.

For Cases 3 and 4 the pumps are tripped at the time of reactor scram.

9.

Auxiliary Feedwater Flow and Delay: In Cases 1 and 3 the steam-driven AFW pump is assumed to fail to start. The motor-driven AFW pumps start as designed 240 seconds after the AFW system actuation signal on low-low SG level is generated. In Cases 2,4, and 5, the "B" motor-driven AFW pump fails to start, but the "A" pump starts normally after the programmed 240 second delay. The steam-driven auxiliary pump is then started 600 seconds (10 minutes) after the reactor trip.

10.

Primary System Charging and Letdown Systems: Charging flow from three charging I

pumps is assumed to be available. Flow is controlled by the pressurizer level controller. Letdown flow is disabled.

11.

Steam Generator Tube Plugging Level:

Cases 1-4:

The maximum level of SG tube plugging permitted by the current licensing basis (500 tubes per generator) is applied. This is a conservative assumption for RCS heatup because it increases the overall temperature differential across the SG tubes at any given power level, it raises average

~

RCS temperature during transients and reduces available steam pressure during steady-state power operation. The reduced steam pressure as an initial condition increases the margin to the MSSV setpoint, thereby requiring additional heatup of the RCS primary before steam can be relieved through the MSSVs.

Siemens Power Corporation Nuclear Division

EMF-98-015 Millstina Unit 2 Less cf Norm:I Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 4 5 Case 5 No SG tube plugging is applied. This is slightly conservative for minimizing SG liquid inventory because it produces the hignest SG pressure when using the steam dumps for post-trip RCS temperature control, thereby minimizing the delivered AFW flow, if SG tube plugging were to be applied, the steam dumps would.still control RCS average temperature at the same point, but SG pressure would be slightly lower due to the reduced heat transfer area and larger tube to shell temperature difference.

I 12.

Reactor Kinetics Feedback and Decay Heat Calculation: Reactor kinetics feedback due to changing primary system conditions prior to reactor scram is calculated using the ANF-RELAP code. Following reactor scram, the nominal ANS 1973 Standard decay heat formulation was applied, including the contribution due to actinide decay. The 20% uncertainty associated with the 1973 Standard was not applied.

13.

Steam Generator Blowdown Flow: The SG blowdown rate is 300 gpm per SG.

j Blowdown is isolated 10 seconds after AFW system actuation on low-low SG level.

The plots of SG blowdown flow accompanying the analysis results in Section 5 show the mass flow rate, which varies as fluid density at the SG secondary tubesheet changes during the transient. The volumetric flow rate is maintained

]

constant at 300 gpm until blowdown is isolated.

1 i

I Siemens Power Corporation Nuclear Division

EMF-98-015 Millston2 Unit 2 Lcss cf Norm:I Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-1 l

5.

Analysis Results 5.1 FSAR Chapter 14 Loss of NormalFeedwater With Offsite Power Available, Steam-

{

Driven AFWPump Falls This event is initiated by an instantaneous loss of all main feedwater. Table 4.1 lists the initial conditions for the transient. Table 4.2 presents the initial plant configuration for the analysis. Figures 5.1 through 5.16 show various parameters from both the primary and secondary system response. Table 5.1 presents the sequence of events for the transient.

Following the loss of feedwater flow, there is a mismatch between primary heat generation by the core and RC pumps and heat removal by the secondary system. This causes a primary side heatup. The resultant coolant thermal expansion causes an insurge into the pressurizer which activates the spray flow for a short period of time at approximately 22 seconss. A teactor trip on low SG water level occurs at 34 seconds.

The SG liquid mass inventory at the time of reactor trip is approximately 68,000 lbm. The main turbine trips automatically following the reactor trip, closing the turbine stop valves.

The Main Steam Safety Valves (MSSVs) open briefly to relieve the secondary pressure increase caused by the turbine trip, then the lowest setpoint bank of MSSVs cycle open and closed to maintain steam pressure at approximately 1000 psia. This steam relief through the MSSVs controls RCS temperatures as the remaining steam generator inventory continues to boil off.

The reactor trip initiates a temporary reduction in RCS temperature and coolant thermal contraction causes a decrease in pressurizer level and pressure. This level decrease initiates charging flow at approximately 345 seconds in response to the pressurizer level control system. Charging flow continues intermittently for the remainder of the transient.

The two motor-driven AFW pumps start at 283 seconds (240 seconds after the AFW system actuation at 43 seconds). The single active failure is applied to the steam-driven AFW pump and no flow is credited from that pump. During the period from 283 seconds to 365 seconds, the flow from the two available motor-driven AFW pumps is not adequate to cause a reduction in RCS temperatures. However, the flow is adequate to prevent any significant primary heatup. The maximum post-trip RCS average temperature of 554 F is reached at 365 seconds. The cooling capability of the AFW system is initially constrained by the physical requirement to purge standing 435 F hot water from the active portion of l

l Siemens Power Corporation - Nuclear Division

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EMF 98-015 Millstona Unit 2 Less of Normtl Fordwst;r Flow Trrnsiint Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-2 the MFW piping. The purge volume is conservatively sized at 141 ft and is not cleared a

until approximately 600 seconds.

A slow decrease in steam generator inventory continues after AFW actuation. At 1706 seconds, minimum SG liquid mass inventory is reached in SG-2 (3,347 lbm), after which SG inventory begins to increase. By 3600 seconds, SG inventory is increasing appreciably, and it is evident that AFW flow is sufficient to ensure continued cooling of the RCS. RCS temperatures remain nearly constant during this period, verifying that stable progress towards safe shutdown is occurring. The plant response is well-behaved throughout the transient.

The results verify that two motor-driven Auxiliary Feedwater pumps have adequate capacity (even with 5% degraded flow) to remove RCS sensible heat, RCP heat, and core decay heat from the primary system and maintain subcooling margin in the reactor coolant system. Additionally, the AFW system response time is adequate to prevent SG dryout and to prevent pressurizer level from exceeding allowable limits (maximum pressurizer level

= 74%).

1 Siemens Power Corporation - Nuclear Division

EMF-98-015 Millstona Unit 2 Loss cf Norm I Fxdwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-3 Table 5.1 Sequence of Events for FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start Time (sec.)

Event O

Totalloss of Main Feedwater 22 Pressurizer spray on i

34.1 Reactor trip signal on low SG water level 35.1 Control rods begin to drop i

36.1 Main Turbine trip 43 Peak Steam Generator pressure (1065 psia) 43 AFW actuation signal on low-low SG water level 45 Maximum pressurizer level. 74%

53 SG Blowdown isolated 283 Two motor driven AFW pumps start 345 Charging flow initiated in response to pressurizer level program 365 Maximum post-trip RCS average temperature (554 *F) 1706 Minimum SG liquid inventory occurs 3600 End of calculation Siemens Power Corporation - Nuclear Division

EMF-98-015 Millst:ne Unit 2 Loss cf Normal Fe<dw;t:r Flow Trcnsient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-4 120.0 C

O Reactor Power (%)

100.0 m

0 31:

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i Siemens Power Corporation - Nuclear Division

f EMF 89-015 Millstone Unit 2 L:ss of Normal Feedwater Flow Transient With Reduced Auxiliary Feedwater F':,w Revision 1 Page 5-5 I

l j

i 650.0 625.0

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i Time (sec) i

- Figure 5.2 RCS Loop Temperatures, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start l

r l

L' i

Siemens Power Corporation Nuclear Division

i EMF.98-015 Millstin2 Unit 2 L:ss of Normil FIIdwat:r Fisw Transient With Reduced Auxiliary Feedwater Flow Revision 1 Page 5-6 2600.0 C

O CNTRLVAR_630 m

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I Figure 5.3 Pressurizer Pressure, FSAR Chapter 14 Analysis with Offsite Power Available.

- Steam-Driven AFW Pump Fails to Start l

I i

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i Siemens Power Corporation - Nuclear Division

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EMF-98-015 Millstone Unit 2 Less cf Normal Feedwater Flow Transient With Reduced Auxiliary Feedwater Flow -

Revision 1 Page 5 7 i

100.0 n

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Figure 5.4 Pressurizer Level, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start i

l l

l Siemens Power Corporation - Nuclear Division

E EMF-98-015 Millst:ne Unit 2 Less cf Normal Fasdw:tIr Fl:w Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-8 60.0 C

D MFLOWJ_630000000 m

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0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec)

Figure 5.5 Pressurizer Spray Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start Siemens Power Corporation. Nuclear Division j

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EMF-98-015 Millst:n2 Unit 2 Loss cf Normal Feedw-tir Fisw Tr:nsient

{

Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-9 100.0 C

O MFLOWL641000000l '

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Figure 5.6 Pressurizer PORV Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start l

l i

Siemens Power Corporation - Nuclear Division

EMF-98-015 Millst:n3 Unit 2 Less of Narrmi Fndw:: tar Fisw Trcnsient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-10 30.0 _,,,,,,,.

C O MFLOWJ 781000000 25.0 n

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Figure 5.7 _RCS Charging Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start t

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l Siemens Power Corporation - Nuclear Division

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EMF-98-015 Millstina Unit 2 Less cf Normal F:edwet:r Fisw Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-11

)

i i

120.0 l

100.0

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)

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Figure 5.8 RCS Loop Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start i

Siemens Power Corporation Nuclear Division

EMF-98-015 Millstona Unit 2 Loss of Normal FrIdwitsr Flow Trtnsi:nt With Reduced Auxiliary Feedwater Flow Revision 1 Page 5-12 1200.0.,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

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-O SG 1 1150.0 C

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Figure 5.9 SG Dome Pressure, FSAR Chapter 14 Analysis with Offrite Power Available, Steam-Driven AFW Pump Fails to Start 3

Siemens Power Corporation - Nuclear Division

EMF-98-015 Millstona Unit 2 Loss of Normil Faedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater F':w Page 5-13 I

i 2000.0 c,

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Figure 5.10 SG Main Steam Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start d

Siemens Power Corporation - Nuclear Division

EMF-98-015 j

Millst:na Unit 2 Less cf Normal Fosdw:ttr Flow Transient P.svision 1 With Reduced Auxiliary Feedwater Flow Page 5-14 i

80.0 70.0 C

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Figure 5.11 SG Narrow Range Level, FSAR Chapter 14 Analysis with Offsite Power l

Available, Steam-Driven AFW Pump Fails to Start t

Siemens Power Corporation Nuclear Division

EMF-98-015 Millstona Unit 2 Less cf NormIl F2Idwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-15 e

i l

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- 15.0

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Figure 5.12 SG Liquid Mass inventory, FSAR Chapter 14 Anelysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start l

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Siemens Power Corporation - Nuclear Division

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EMF-98-015 Millst na Unit 2 Less cf Norm;l FIIdwitir Fisw TrInsi;nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-16 I

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Figure 5.13 SG Collapsed Liquid Level, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start t

i Siemens Power Corporation - Nuclear Division

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l EMF-98-015 Millst:n2 Unit 2 Loss of N rrn;l Fc:dwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-17 l

l 1

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Figure 5.14 SG Auxiliary Feedwater Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start I

l Siemens Power Corporation Nuclear Division

EMF-98-015 Millsttro Unit 2 Less cf Normtl Fsedwit:r Fisw TrrnsiInt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-18

}

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I Figure 5.15 SG Blowdown Flow, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start

)

1 I

I

. Siemens Power Corporation - Nuclear Division

Millstin] Unit 2 Less cf Normal FIcdwater Flow Transient EMF-98-015 With Reduced Auxiliary Feedwater Flow Revision 1 Page 5-19 l

1 l

L 1600.0 1440.0 C

O SG 1 C

0 SG 2 1280.0 m

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.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec) l Figure 5.16 SG Thermal Power, FSAR Chapter 14 Analysis with Offsite Power Available, Steam-Driven AFW Pump Fails to Start l

i Siemens Power Corporation - Nuclear Division

)

EMF-98-015 l

Millstan2 Unit 2 Less of Normd Ferdwitir Fisw Trtnsi:nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-20 l

4 i

5.2 FSAR Chapter 14 Loss of Norms /Feedwater With Offsite Power AvaHable One Motor-Driven AFWPlump FaHs

\\

t This event is initiated by an instantaneous loss of all main feedwater. Table 4.1 lists the I

initial conditions for'the transient. Table 4.2 presents the initial plant configuration for the analysis. Figures 5.17 through 5.32 show various parameters from both the primary and t

secondary system response. Table 5.2 presents the sequence of events for the transient, t;

Following the loss of feedwater flow, there is a mismatch between primary heat generation by the core and RC pumps and heat removal by the secondary system. This causes a primary side heatup. The resultant coolant thermal expansion causes an insurge f

into the pressurizer which activates the spray flow for a short period of time at t

' approximately 22 seconds. A reactor trip on low SG water level occurs at 34 seconds.

[

The SG liquid mass inventory at the time of reactor trip is approximately 68,000 lbm. The main turbine trips automatically following the reactor trip, closing the turbine stop valves.

- The MSSVs open briefly to relieve the secondary pressure increase causev by the turbine trip, then the lowest setpoint bank of MSSVs cycle open and closed to maintain steam pressure at approximately 1000 psia. This steam relief through the MSSVs controls RCS temperatures as the remaining steam generator inventory continues to boil off, i

i i

The reactor trip initiates a temporary reduction in RCS temperature and coolant thermal contraction causes a decrease in pressurizer level and pressure. This level decrease j

initiates charging flow at approximately 348 seconds in response to the pressurizer level

{

control system. Charging flow continues intermittently for the remainder of the transient.

i i

~

The "A" motor-driven AFW pump starts at 283 seconds (240 seconds after the AFW system actuation at 43 seconds). The single active failure is applied to the "B" motor-l driven AFW pump and no flow is credited from that pump. During the period from 283 seconds to.635 seconds, the flow from the "A" motor-driven AFW pump is not adequate I

to cause a reduction in RCS temperatures. However, the flow is adequate to prevent any i

{

significant primary heatup. The maximum post-trip RCS average temperature of 554.4*F is reached at 413 seconds. The steam-driven AFW pump actuates at 635 seconds (600 l

l seconds after the reactor trip on low SG level). The cooling capability of the AFW system i

is initially constrained by the physical requirement to purge standing 435'F hot water from

{

the active portion of the MFW piping. The purge volume is conservatively sized at 141 ft8 and is not cleared until approximately 722 seconds.

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-v v

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r EMF-98-015 l

Millst

n2 Unit 2 Less cf N rmal Fstdwater Flow Transient Revision 1

- With Reduced Auxiliary Feedwater r!ow i

p Page 5 21 A slow decisase in steam' generator inventory continues after AFW actuation. At 728 i.

seconds minimum SG liquid mass inventory is reached in EG-1 (1,140 lbm); after which e

- SG inventory begins to increase. By 2400 seconds, SG inventory is increasing appreciably, and it is evident that AFW flow is sufficient to ensure continued cooling of the j

c RCS. RCS temperatures remain nearly constant during this period, verifying that stable progress towards safe shutdown is occurring. The plant response is well-behaved i

throughout the transient.

s

' The results verify that the' combination of one motor driven AFW pum' and the steam-p driven AFW pump have adequate capacity (even with 5% degraded flow) to remove RCS l

sensible heat, RCP heat, and core decay heat from the primary system and maintain subcooling margin in the reactor coolant system. Additionally, the AFW system response time is adequate to prevent SG dryout and to prevent the pressurizer level from exceeding

- allowable limits (maximum pressurizer level = 74% at 45 seconds).

1 l

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/ Siemens Power Corporation - Nuclear Division

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EMF-98-015 Millst::n2 Unit 2 Loss cf Normal Fssdwatzr Flow Trsnsirnt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-22 Table 5.2 Sequence of Events for FSAR Chapter 14 Analysis with Offsite Power Available, One Motor-Driven AFW Pump Fails to Start Time (sec.)

Event O

Totalloss of Main Feedwater 22 Pressurizer Spray on 34.1 Reactor trip signal on low SG water level 35.1 Control rods begin to drop 36.1 Main Turbine trip 43 Peak Steam Generator Pressure (1065 psia) 43 AFW Actuation signal on low-low SG water level 45 Maximum pressurizer level, 74%

53 SG Blowdown isolated 2S3 Train "A" motor-driven AFW pump starts 348 Charging flow initiated in response to pressurizer level program 350 Maximum post-trip RCS average temperature (554 *F) 635 Steam-driven AFW pump starts 728 Minimum SG liquid inventory occurs 2400 End of calculation

~

1 Siemens Power Corporation Nuclear Division

i EMF-98-015 Millst:ne Unit 2 L:ss of N:rmal Fcedwater Flow Transient With Reduced Auxiliary Feedwater Flow Revision 1 i

Page 5-23 1

l 120.0 C

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j Motor-Driven AFW Pump Fails to Start i

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EMF-98-015 Millst:ne Unit 2 Less of N:rmal FIcdwat;r Fisw Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-24 650.0 625.0

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Figure 5.18 RCS Loop Temperatures, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start Siemens Power Corporation - Nuclear Division

r EMF-98-015 Mill:tona Unit 2 Less cf Normal Feedwater Flow Transient Revision 1' With Reduced Auxiliary Feedwater Flow Page 5-25 4

2600.0 C

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Figure 5.19 Pressurizer Pressure, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start 1

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l EMF-98-015 Millst na Unit 2 Lo2s of Norm:I Feedwat:r Flow Transient Revision 1

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Figure 5.20 Pressurizer Level, FSAR Cbapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start i

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EMF-98-015 Millstone Unit 2 Liss cf Normal Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-27 i

60.0 i

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Figure 5.21 Pressurizer Spray Flow, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start l

i Siemens Power Corporation Nuclear Division

EMF-98-015 Millst na Unit 2 Less cf Norm:I FcIdw tir Flow TrznsiInt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-28 100.0 C

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..Siemens Power Corporation Nuclear Division

EMF-98-015

(

Millst na Unit 2 Less cf Normtl FIIdwater Flow Transient Revision 1

- With Reduced Auxiliary Feedwater Aow Page 5-29 i

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Figure 5.23 RCS Charging Flow, FSAR Chapter 14 Analysis with Offsite Power Available,

~B" Motor Driven AFW Pump Fails to Start 1

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EMF-98-015 Millst:n2 Unit 2 Less of N:rm::1 F cdwat r Flow Transi:nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-30 l

120.0 l

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EMF-98-015 Millstona Unit 2 Lo:s of Norm I Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-31 1200.0 _,,,,...,,,,,,,,,,,,,,,,,

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1000.0 q) 950.0 h

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Figure 5.25 SG Dome Pressure, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start t

Siemens Power Corporation Nuclear Division

EMF-98-015 Millstons Unit 2 Loss of Normsl Fudwstgr Flow Transisnt Revision 1 4

With Reduced Auxiliary Feedwater Flow Page 5-32 l

2000.0 i

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Figure 5.26 SG Main Steam Flow, FSArt Chapter 14 Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start Siemens Power Corporation Nuclear Division i'

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i EMF-98-015 Millst:ne Unit 2 Liss cf Normal Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-33 i

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i Siemens Power Corporation Nuclear Division I

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EMF-98-015 Mill;t:n3 Unit 2 Loss cf Norm:l Fredw t:r Fiow Tr:nsient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-34 O

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' Available, "B" Motor-Driven AFW Pump Fails to Start s

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. Siemens Power Corporation Nuclear Division

1 EMF 98-015 Millstone Unit 2 L:ss cf N:rrmi Feedwater Flow Transient With Reduced Auxiliary Feedwater Flow Revision 1 Page 5 35 i

i 20.0 18.0 C

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l Siemens Power Corporation - Nucloor Division l

EMF-98-015 Millston2 Unit 2 Loss of Normil FcIdw:t:r Flow Trcnsiint s

Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-36 50.0

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Figure 5.30 SG Auxiliary Feedwater Flow, FSAR Cnapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start l

l Siemens Power Corporation - Nuclear Division

1 EMF 98-015 Millst:na Unit 2 Less cf Norm:I Focdw;t:r Fl:w Tr:nsi:nt With Reduced Auxiliary Feedwater Flow Revision 1 I

Page 5 37 i

e h

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Figure 5,31 SG Blowdown Flow, FSAR Chapter 14 Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start i

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EMF-98-015 l

Millst:n2 Unit 2 Loss cf N:rm:I F=dwat:r Fl:w Tr nsi:nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-38 1

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Figure 5.32 SG Thermal Power, FSAR Chapter 14 Analysis with Offsite Power Available, I

~B" Motor-Driven AFW Pump Fails to Start l

l t

Siemens Power Corporation - Nuclear Division

EMF 98-015 Millst:n) Unit 2 Less of Norm I FGIdwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-39 5.3 i

FSAR Chapter 14 Loss of NormalFeedwater With Loss of Offsite P6wer, Steam-Driven AFWPump Falls This event is initiated by an instantaneous loss of all main feedwater. Table 4.1 lists the 4

initial conditions for the transient. Table 4.2 prasents the initial plant configuration for the i

analysis. Figures 5.33 through 5.48 show various parameters from both the primary and i

secondary system response. Table 5.3 presents the sequence of events for the transient.

Following the loss of feedwater flow, there is a mismatch between primary heat generation by the core and RC pumps and heat removal by the secondary system. This causes a primary side heatup. The resultant coolant thermal expansion causes an insurge into the pressurizer which activates the spray flow for a short period of time at approximately 22 seconds. A reactor trip on low SG water level occurs at 34 seconds.

The SG liquid mass inventory at the time of reactor trip is approximately 68,000 lbm. A loss of offsite power is postulated to occur coincident with the reactor trip, and the RCPs are tripped. The available driving pressure for pressurizer spray flow decreases to zero as the RC pumps coast down. The main turbine trips automatically following the reactor trip, closing the turbine stop valves. The MSSVs open briefly to relieve the secondary pressure increase caused by the turbine trip, then the lowest setpoint bank of MSSVs cycle open and closed to maintain steam pressure at approximately 1000 psia. This steam relief through the MSSVs controls RCS temperatures as the remaining steam generator inventory continues to boil off.

Following the initial temperature decrease and coolant shrinkage due to reactre scram, the RCP trip and primary flow coast down contributes to an increase in RCS average temperature. Charging flow actuates at 73 seconds in response to demand from the F.1surizer level control program. Primary coolant expansion causes an insurge into the l

pret,surizer and charging flow continues (utilizing all three charging pumps) until 170 seconds at which point the Tavg programmed levelis restored. The degradation of primary to secondary heat transfer causes the primary average temperature to increase

(

from approximately 564*F to 571 *F during the period from 100 to 850 seconds.

Pressurizer spray flow is insignificant following the RC pump trip.

The two motor driven AFW pumps start at 281 seconds (240 seconds after the AFW system actuation on low-low SG level at 41 seconds). The single active failure is applied to the steam-driven AFW pump and no flow is credited from that pump. During tne period l

l t

Siemens Power Corporation - Nuclear Division

r EMF-98-015 l

Millstona Unit 2 Less of N:rm:I Fcidwat r Fisw Trnsiint Revision 1 l

With Reduced Auxiliary Feedwater Flow Page 5-40 t

from 281 seconds to 900 seconds, the flow from the two available motor-driven AFW pumps is not adequate to cause a reduction in RCS temperatures. However, the flow is i

adequate to prevent any sigrificant primary heatup. The maximum post-trip RCS average temperature of 571.7'F is reached at 855 seconds. The cooling capability of the AFW system is initially constrained by the physical requirement to purge standing 435 *F hot f

t water from the active portion of the MFW piping. The purge volume is conservatively sized at 141 ft' and is not cleared until approximately 594 seconds.

L A slow decrease in steam generator inventory continues after AFW actuation. At 596 seconds, minimum SG liquid mass inventory is reached in SG-1 (19,505 lbm), after which SG inventory begins to increase. By 3600 seconds, SG inventory is increasing apprec:4;y, and it is evident that AFW flow is sufficient to ensure continued cooling of the f

RCS. RCS temperatures remain nearly constant during this period, verifying that stable

. progress towards safe shutdown is occurring. The plant response is well-behaved l

throughout the transient.

i The results verify that two motor-driven Auxiliary Feedwater pumps have adequate I

capacity (even with 5% degraded flow) to remove RCS sensible heat and core decay heat

'}

from the primary' system and maintain subcooling margin in the reactor coolant system i

i under natural circulation conditions. - Addit!onally, the AFW system response time is

{

adequate to prevent SG dryout and to prevent the pressurizer level from exceeding allowable limits. The maximum pressurizer level (76.3%) occurs early in the event at 43 I

-seconds.

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Siemens Power Corporation Nuclear Division -

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EMF-98-015 Millst:n3 Unit 2 Loss of N:rm:I F:cdw:ter Flow Transient With Reduced Auxiliary Feedwater Flow Revision 1 I

Page 5-41 l

l Table 5.3 Sequence of Events for FSAR Chapter 14 with Loss of Offsite Power, Steam-Driven AFW Pump Fails to Start j

t t

Time (sec.)

Event i

O Totalloss of Main Feedwater 34.1 Reactor trip signal on low SG water level 1

35.1 Control rods begin to drop: RCPs tripped 36.1 Main Turbine trip 1

39 Pressurizer PORV cycles open/ closed 41 AFW actuation signal on low-low SG water level t

43 Maximum pressurizer level, 76%

46 Peak Steam Generator pressure (1055 psia) i 51 SG Blowdown isolated l

l

~

73 Charging flow on (pressurizer level below prograrn) 170 Charging flow off (pressurizer level at program setpoint) l l

l 281 Two motor-driven AFW pumps start 596 Minimum SG liquid inventory occurs i

855 Maximum post-trip RCS average temperature (571 "F) 3600 End of calculation l

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Siemens Power Corporation - Nuclear Division

l EMF-98-015 Millstuna Unit 2 L%s cf Normil Fcedw tir Flaw Tr:nsi;nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-42 r

r 120.0 C

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Figure 5.33 Reactor Power, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start l

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l Siemens Power Corporation - Nucleer Division i

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EMF-98-015 Millst*nt Unit 2 L:ss cf Normal Feedwater Flow Transient Revision 1

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Figure 5.34 RCS Loop Temperatures, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start I

I l

i Siemens Power Corporation - Nuclear Division

EMF 98-015 Millst:n2 Unit 2 Less cf NormIl Fssdwat;r Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-44 i

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Figure 5.36 Pressurizer Level, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start 1

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' With Reduced Auxiliary Feedwater Flow Page 5-46

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Figure 5.37 Pressurizer Spray Flow, FSAR Chapter 14 Analysis without Offsite Power

' Available, Steam-Driven AFW Pump Fails to Start i

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t

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.t

.. m.Im...

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec)

Figure 5.38 Pressurizer PORV Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Purto Fails to Start l

l' i

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Siemens Power Corporation - Nuclear Division l

EMF-98-015 Millst:ro Unit 2 Loss cf Ntrm:I F:cdwrtir Fl w TrInsi:nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-48 30.0 C

D MFLOWJ 781000000 m 25.0

~

o o

M-

\\

f 20.0 a

3 h 15.0 f_.

~

cn

.5 cp b 10.0 -

r O

m U

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.0 5

.. -.... i -... i.-... i. -., i.

.m..i..-.i-... ~

.0 500.0 1000.0 1500.0 2000.0 2500.0 2000.0 3500.0 4000.0 Time (sec)

Figure 5.39 RCS Charging Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start i

Siemens Power Corperation - Nuclear Division

r EMF-98-015 Millst:n3 Unit 2 Less cf Norm:l F edw:t:r Fisw TrInsirnt Revision 1

.With Reduced Auxiliary Feedwater Flow Page 5-49 120.0 C

O RCP Loop 1A C

O RCP Loop 18 100.0 o

a RCP Loop 2A C

0 RCP Loop 2B n6 80.0 it

.9 La 60.0 c.

O O

-.1 y) 40.0 -

U Q:

i 20.0 -

i i

i. '.

g O. a. 0. X..

t_.

.. r', O., a, g 0,0,. v.,00

a.,,, '

0 1

i v

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 l

Time (sec)

Figure 5.40 RCS Loop Flow, FSAR Chapter 14 Analysis without Offsite Power Available, i

Steam-Driven AFW Pump Fails to Start Siemens Power Corporation

• Nuclear Division

EMF-98-015 Millstena Unit 2 Less of Normil Fstdwat:r Flow Trcnsi2nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-50 l

i 1200.0 1150.0

.~

C O

SG 2 1100.0

^ 1050.0

~

O 1000.0 v

o b

950.0

/

m m

8 900.0 Q.

O 850.0

_~

V) j 800.0 750.0 700.0

.i i,,.,i..

.i,,,,i,,,,i,,,,.,,,,:

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec)

Figure 5.41 SG Dome Pressure, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start l

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Siemens Power Corgaration-Nuclear Division i

EMF 98-015 Mitiston2 Unit 2 Loss of Normti F:4dwatzr Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-51 2000.0 C

O SG 1 1800.0 i

C O

SG 2 1600.0 M

1 N

i E 1400 0 4

a v

12;;.0 2

O i

E 1000.0 E

o 800.0

=

o b

O 600.0

.s 0

2 400.0 ;

l 200.0

.0 11 il JB l

i 3 Il l

I.,,1b d L..,u, h A 1

. d

,n,,,

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec)

Figure 5.42 SG Main Steam Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start i

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Siernens Power Corporation - Nuclear Division

EMF-98 015 Mill:t:ne Unit 2 Loss of N:rmal Fudw:ttr Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-52 I

i 80.0 i

70.0 i bb C

O SG 2' i Q

60.0 U

v 3

50.0

>o 3

J 40.0 I

0c) t 30 0

'O Q:

g 20.0-4

{

ou b

10.0 z

-(

O

.0 O

CO OO O O O

O O

2 v1 r

t

~

-10.0 -

2 l

r

-2.0.0 -

1

..i..

.i....i..

.i...,,

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec) e Figure 5.43 SG Narrow Range Level, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start t

P t

Siemens Power Corporation - Nucisar Division

i EMF.98-015 I

Millst:n3 Unit 2 Less cf N:rmal Fiedwater Flow Transient

'With Reduced Auxiliary Feedwater Flow Revision 1 Page 5-53 i

O 15.0 i

.,,,s

..i..

.i....

C O SG-1 Liquid Mass 3

C o SG-2 Liquid-Mass 12.5 n

E

'o 10.0

_O m

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-2 7.5

~

i

.2

~

\\

a

,?

_J 5.0 -

i i

)

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t' 2.5 -

_m

\\

j

.0 ~

i.

..i l

.0 500.0 1000.0

'1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec) i f

Figure 5.44 SG Liquid Mass inventory, FSAR Chapter 14 Analysis without Offsite Power

'i l

Available, Steam-Driven AFW Pump Fails to Start i-Siemens Power Corporation - Nuclear Division

EMF 98-015 Millstona Unit 2 Loss cf N:rmrl F21dwit:r Fl:w Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5 54 i

20.0

~

18.0 C

O SG 1 m

C 0

SG 2

~

C 16.0 v

3 O

14.0 h

-[

1 12.0 2

2

.? 10.0 2

J j

8.0 m

fl.

_O 6.0 -

2 0

O 4.0 -

0 ln

~

2.0 -

.0

...i....r.

...i i....t

,.,,i....

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (Sec)

Figure 5.45 SG Collapsed Liquid Level, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start l

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Siemens Power Corporation Nuclear Division

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EMF-98-015 Millst:n? Unit 2 Less cf Normal F :dwIter Flow Transient With Reduced Auxiliary Feedwater Flow Revision 1 Page5 55 I

I 50.0 C

D SG 1 45.0 C

O SG 2 40.0 m

U 8 35.0 h

N E

30,o i

25.0 u.

20.0 3:

u.

< 15.0 _-

0 M 10.0.

5.0 -

~

s

.0

.t t

....t

....t

....t

....t

....t

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec)

Figure 5.46 SG Auxiliary Feedwater Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start I

l Siemens Power Corporation - Nuclear Division

. ~ _ _

t EMF-98-015 Millst:n] Unit 2 L:ss of N:rmal Fcedwatir Flow Tr nsi;nt Revision 1

- With Reduced Auxiliary Feedwater Flow Page 5-56 l

40.0 35.0 C

O SG 1 C

0 SG 2 no 30.0 a) v)\\

25.0 E

p 3

20.0 3o g

15.0 C

3 10.0 -

o V

3 5.0 '-

-o CD

.0 ED 00 OO O O O

O D

g g

-5.0 -

- 10.0

.... i.

. i

... i i... i.... r....i....i...2

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (SOC)

Figure 5.47 SG Blowdown Flow, FSAR Chapter 14 Analysis without Offsite Power Available, Steam Driven AFW Pump Fails to Start i

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Siemens Power Corporation. Nuclear Division

EMF-98-015 Millst;na Unit 2 Loss of Normn Feedwater Flow Transient Revision 1

- With Reduced Auxiliary Feedwater Flow Page 5-57 l

t 1600.0 i

I 1440.0 C

D SG 1 C

0 SG 2

.?

1280.0 m

3:

2 1120.0 v

u o

960.0 3l:

o 0-800.0 O

E e40.0 u

y

.c H

480.0 O

~

W 320.0-

~

160.0 --

1

""I' % D...

.0

"~ '

!=

l

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec) f Figure 5.48 SG Thermal Power, FSAR Chapter 14 Analysis without Offsite Power Available, Steam-Driven AFW Pump Fails to Start t

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Siemens Power Corporation - Nuclear Division

_ _ _ _.... _. _ _ _ _ _ _ _ _.. _ _ _ _ _. ~._ _.. _ _

l EMF-98-015 Millstons Unit 2 Loss of Normtl Fatdwstir Flow TrcnsiInt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5 58 5.4 FSAR Chapter 14 Loss of NormalFeedwater With Loss of Offsite kwer, One Motor-Driven AFWkmp Fails i

This event is initiated by an instantaneous loss of all main feedwater. Table 4.1 lists the initial conditions for the transient. Table 4.2 presents the initial plant configuration for the j-analysis. Figures 5.49 through 5.64 show various parameters from both the primary and 4

secondary system response. Table 5.4 presents the sequence of events for the transient.

i i

i j

Following the loss of feedwater flow, there is a mismatch between primary heat "

generation by the core and RC pumps and heat removal by the secondary system. This causes a primary side heatup. The resultant coolant thermal expansion causes an insurge into the pressurizer which activates the spray flow for a short period of time at '

[

approximately 22 seconds. A reactor trip on low SG water level occurs at 34 seconds.

The SG liquid mass inventory at the time of reactor trip is approximately 68,000 lbm. A loss of offsite power is postulated to occur coincident with the reactor trip, and the RCPs

.are tripped. The available driving pressure for pressurizer spray flow decreases to zero as

. t the RC pumps coast down. The main turbine trips automatically following the reactor trip, i

L closing.the turbine stop valves. The MSSVs open briefly to relieve the secondary pressure i

increase caused by the turbine trip, then the lowest setpoint bank of MSSVs cycle open I

and closed to maintain steam pressure at approximately 1000 psia. This steam relief through the MSSVs controls RCS temperatures as the remaining steam generator inventory continues to boil off.

Following the initial temperature decrease and coolant shrinkage due to reactor scram, the RCP trip and primary flow coast' down contributes to an increase in RCS average l

' temperature. Charging flow actuates at 73 seconds in response to demand from the

[

pressurizer level control program. Primary coolant expansion causes an insurge into the pressurizer and charging flow continues (utilizing all three charging pumps) until 170 seconds at which point the Tavg programmed level is restored. The degradation of primary to secondary heat transfer causes the primary average temperature to increase i

from approximately 564*F to 571 *F during the period from 100 to 757 seconds, i

Pressurizer spray flow is insignificant following the RC pump trip, 3

- The train "A" motwenven AFW pump starts at 281 seconds (240 seconds after the AFW t'

system actuation on low low SG level at 41 seconds). The single active failure is applied to the train "B" motor-driven AFW pump and no flow is credited from that pump. During Siemens Power Corporation Nucteer Division-im r-

w. w r----

E I

p EMF-98-015 Millst:na Unit 2 Less of Norm I F2:dwat:r Flew Transiint -

Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-59 l

L i

the period from 281 seconds to 814 seconds, the AFW flow is not adequate to cause a reduction in RCS temperatures. However, the flow is adequate to prevent any significant primary heatup. The maximum post-trip RCS average temperature of 571.8*F is reached at 757 seconds. The steam driven AFW pump actuates at 635 seconds (600 seconds after the reactor trip on low SG levs!). The cooling capability of the AFW system is initially constrained by the physical requirement to purge standing 435 F hot water from the active portion of.the MPN piping. The purge volume is conservatively sized at 141 ft' and is not cleared until approximately 721 seconds.

A slow decrease in steam generator inventory continues after AFW actuation. At 730 seconds, minimum SG liquid mass inventory is reached in SG-2 (14,592 lbm), after which SG inventory begins to increase. By 2400 seconds, SG inventory is increasing appreciably, and it is evident that AFW flow is sufficient to ensure continued cooling of the RCS. RCS temperatures remain nearly constant during this period, verifying that stable progress towards safe shutdown is occurring. The plant response is well-behaved throughout the transient.

The results verify that the combination of one motor-driven AFW pump and the steam-

)

driven AFW pump have adequate capacity (even with 5% degraded flow) to remove RCS i

i sensible heat and core decay heat from the primary system and maintain subcooling in the reactor coolant system under natural circulation conditions. Additionally, the AFW system response time is adequate to prevent the pressurizer level from exceeding allowable limits.

The maximum pressurizer level (76.3%) occurs early in the event at 43.0 seconds.

l l

r-l Siemens Power Corporation Nuclear Division

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. - ~

EMF-98-015 Millstona Unit 2 L:ss of N:rmil Fndwetir Flow Transi:nt With Reduced Auxiliary Feedwater Flow Revision 1 Page 5-60 j

l Table 5.4' Sequence of Events for FSAR Chapter 14 with Loss of Offsite Power, One Motor-Driven AFW Pump Fails to Start Time (sec.)

Event O

Totalloss of Main Feedwater 34.1 Reactor trip signal on low SG water level 35.1 Control rods begin to drop; RCPs tripped 36.1 Main Turbine trip 39 Pressurizer PORV cycles open/ closed 41 AFW actuation signal on low-low SG water level signal 43 Maximum pressurizer level, 76%

46 Peak Steam Generator pressure (1055 psia) 51 SG Blowdown isolated 73 Charging flow on (pressurizer level below program) 170 Charging flow off (pressurizer level at program setpoint) 281 Train "A" motor-driven AFW pump starts 635 Steam-driven AFW pump starts 730 Minimum SG liquid inventory occurs 757 Maximum post-trip RCS average temperature (571*F) 2400 End of calculation -

Siemens Power Corporation - Nuclear Dwision

EMF-98-015 Mitist:n3 Unit 2 Loss of Normal Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Clow Page 5-61 120.0 O Reactor Power (%)

[

C 100.0 I u

e.

s

[

80.0 e

~

O u

O o

60.0 e

g

~

C

~

0 40.0 i

U u

g 20.0 -

9 1

j Oi O

.C.

.C C,

.0

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec) 1 Figure 5.49 Reactor Power, FSAN Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start i

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Siemore Power Corporation Nuclear Division

EMF-98-015 Millstin] Unit 2 Les2 of N:rmal FeldwatIr Flow Tr:nsi:nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-62 i

650.0 625.0 L.

I.

600.0 cn g

O m

8 575.0

+

r

-C-M

---a 3

O u

a-

h. -

\\

S 550.0 E

~-

s o

F-525.0 D - -O RCS Hot Leg Temp.

2 I

C 0

RCS Cold Leg Temp.

500.0-

~

o a

RCS Average Temp.

i i

.0 s0 J 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec) l 1

Figure 5.50 RCS Loop Temperatures, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start i

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l Siemens Power Corporation - Nuclear Division n

EMF-98-015 Millst::n2 Unit 2 Loss of Normal Feedwater Flow Transient Revision 1 i

With Reduced Auxiliary Feedwater Flow Page 5-63 1

I 1

2600.0 3

~

C O CNTRLVAR 630 m

'h 2400.0 s

x I

o u

3 m

M U

2200.0 CL

~

u W

o

.N u

3 m

m 2000.0

,o La

~

1800.0 i

i i

i i

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec)

Figure 5.51 Preasurizer Pressure, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start 1

l l

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l Siemens Power Corporation - Nuclear Division

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?:

EMF-98-015 Millst:n3 Unit 2 L:ss of Normil Fridwatir Fisw Trtnsi:nt Revision 1 With Reduced Auxiliary Feedwater Flow -

Page 5-64 a

?

100.0 i

m Co 75.0 -t a.

y' 8

M a-,

v

-g 50.0 1

u O

.N u

3 m

m 25.0 o

u Q.

fC O CNTRLVAR_620 l

.0 i

i i

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec)

Figure 5.52 Pressurizer Level, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start i

\\

l 1

1 l

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. Siemens Power Corporation - Nuclear Division e

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1 i-EMF-98-015 Millston] Unit 2 L:ss cf Normtl F:edwater Flow Transient With Reduced Auxiliary Feedwater Flow Revision 1 1

Page 5-65 1

i 60.0 l

C O MFLOWJ_630000000

^

Oo 50.0 m

{

N 3

1 E

v 40.0 3

o b.

l 30.0 1

x O

u c.

(M u 20.0 o

.U u

3 (n

m ? O.0 2

o

.t Q'.

)

A

.o,

i a

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0

-Time (sec)

Figure 5.53 Pressurizer Spray Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start l

l Siemens Power Corporation - Nuclear Division

EMF-98-015 Millstona Unit 2 Loss cf N:rm:1 Fagdwit:r Fl:w Transient Revision 1 l

With Reduced Auxiliary Feedwater Flow Page 5-66 i

1 100.0 C

D MFLOWJ 641000000

^

l 0

O (n

\\

75-E

_o O

k

_o LL.

~

1

~

50.0 y

O' O

CL

~

u.

N i

o "E

25.0 -

3 v1 cn O

i u

D.

~

.0 i

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (Sec)

Figure 5.54 Pressurizer POIN Flow, FSAR Chapter 14 Analycis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start I

t t

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l Siemens Power Corporation Nuclear Divirion i

1 I

EMF-98-015 Millst:ne Unit 2 L:ss of Normal Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow-Page 5-67 1

30.0 C

C MFLOWJ 781000000 m 25.0 O.

U v)

~

E 20.0

~

n v

3 t

O C 15.0 Os

.C os o 10.0 2

.c U

~

(n O

5.0

[

CC i

.0 5 i

i

.-i.

imi i

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec)

B Figu~e 5.55 RCS Charging Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start I

i Siemens Power Corporation _- Nuclear Division

3 EMF-98-015 Millst:na Unit 2 Loss of Narmil Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-68 i

]

120.0 i

i C

O RCP Loop 1A

[

i:

C O

RCP Loop 18

~

100.0 o

a RCP Loop 2A C

0 RCP Loop 2B

[

m 8

80.0

-5

'v o

L.

60.0 Q.

O O

J (n

40.0 O

E 1

20.0

-coa 0 O'O a O C. 'O.

a.

0" O

.0 -

Y

.0 400.0 800.0 1200.0 1600.0 2000.0 2400 0 Time (sec)

Figure 5.56 RCS Loop Flow, FSAR Chapter 14 Analysis without Offsite Power Available,

~6" Motor Driven AFW Pump Fails to Start l

. Siemens Power Corporation - Nucioer Division i

l-Millston: Unit 2 Loss cf Normal Feedwater Flow Transient EMF 98-015 Revision 1

~ With Reduced Auxiliary Feedwater Clow l

Page 5-69 1200.0 1150.0 C

D SG 1 C

O SG 2 5

1100.0

^ 1050.0 h

0

~

v 1000.0 IM o

l 950.0

}

v) y)

8 900.0

~

Q.

O 850.0

~

J

^

(

800.0 -

f 750.0 700.0 -

i i

i i

l

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec)

Figure 5.57 SG Dome Pressure, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start I

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i Siemens Power Corporation Nuclear Division

. - - - -.~

EMF-98-015 Millston) Unit 2 Loss of Normal Ferdw:t:r Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-70 l

2000.0 C

O SG 1 C

0 SG 2 3

3 1600.0 E

'*00-o 1200.0 o

L.

1000.0 E

o 800.0 2

?

b 600.0

~

l 5

c g

l !,

l 2

400.0 1

i l

200.0 -

l li, j

k

' l n

i h r l

.0 l

i j i.

l i i

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec) l Figure 5.58 SG Main Steam Flow, FSAR Chapter 14 Analysis without Offsite Power s

Available, "B" Motor Driven AFW Pump Fails to Start Siemens Power Corporation - Nuclear Division

EMF-98-015 Millstrna Unit 2 Loss of N:rmal Feedwater Flow Transient With Reduced Auxiliary Feedwater Flow Revision 1 Page 5 71 4

50.0 70.0 C

O SG 1

[

C O

SG 2 i

Q 60.0 j

v Ty 50.0

~

g J

40.0 [

g cn C

30.0 o

e 20.0 y

0 b

10.0 L

p z

h(

C)

.0 00 OO O

O 1

u).

-10.0 -

2

-20.0 ~.

i i

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec)

Figure 5.59 SG Narrow Range Level, FSAR Chapter 14 Analysis without Offsite Power Available, ~B" Motor-Driven AFW Pump Fails to Start 1

i Siemens Power Corporation - Nuclear Divisic

EMF-98-015 Millst:n3 Unit 2 Less cf N:rm:.1 Feedwater Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-72 eo 15.0 7

t O

O SG-1 Liquid Moss 5

C 0 SG-2 Liquid Mass 12.5 m

E

.o 10.0 v

m m

0 2

7.5 u

5

.E J

5.0 -

O tn

' 2.5 -

1

.0 -

\\

....i..

.i...

i....i....i...

i....i....~

.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 Time (sec)

Figure 5.60 SG Liquid Mass inventory, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start l

Siemens Power Corporation - Nuclear Division

F:

l' EMF-98-015 Millst:na Unit 21.oss of Normal Feedwater Flow Trans'ent Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-73 P

20.0 18.0 O

O SG 1 C

0 SG 2 O

16.0 3

0 14.0 v

)

12.0

.E a

.? 10.0 J

}

8.0 (n

Q.

O 6.0 -

^

O O

~

4.0 -

O (A

2.0 -

.0 i

i

,,,i,,,i,,

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 IilTit (SBC)

Figure 5.61 SG Collapsed Liquid Level, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start i

l l

l Siemens Power Corporation Nuclear Division i

EMF-98-015 Millst:na Unit 2 Loss of Normal FsIdw ttr Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-74 50.0

~

45.0 c

a sc 1 C

0 SG 2 40.0 h

2 m

0 1

30.0 c

f 3: 25.0

,o u.

20.0 3:

w

< 15.0 1

c)

W 10.0 h

1 5.0 }

l

.0 t

t e

t

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec)

Figure 5.62 SG Auxiliary Feedwater Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start l

l Siemens Power Corporation - Nuclear Division

... ~ _... = _.

l EMF-98-015 Millst:na Unit 2 Less of N:rm:1 F:Idwater Flow Transient Revision 1 With Reduced Auxilury Feedwater Flow Page 5 75 40.0 35.0 C

O SG 1 C

O SG 2 n

0 30.0 tu in

\\

~

25.0 h

E

.o 1

20.0 3

{

o J

[

15.0

~

c 3

10.0 o

V

~

.y 50 :

.o CD

.0 :

00 00 0

0

{

0 (A

-5.0 1 1

-10.0 -

i i

i

.0 400.0 800.0

-1200.0 1600.0 2000.0 2400.0 Time (SeC)

Figure 5.63 SG Blowdown Flow, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start j

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Siemens Power Corporation - Nuclear Division

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1 EMF-98-015 Millston2 Unit 2 Loss of N:rmal Fndw:tir Fl w Tr nsient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-76 i

I 1600.0 1440.0 C

O SG 1

}

C O

SG 2 1280.0

~

^

3:

2 1120.0 2

v c) 960.0 L

2 3

o 1

800.0 h

2 f

0 E

640.0 u

2 o

.c t--

480.0 o

W 320.0 h

2

s 160.0 h

2 M G.

W^@

~ ^

~

~ ' " ' " ^ "

o

.0 400.0 800.0 1200.0 1600.0 2000.0 2400.0 Time (sec)

Figure 5.64 SG Thermal Power, FSAR Chapter 14 Analysis without Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start

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1 Millstons Unit 2 Loss cf Normal Fazdwitzr Flow Transient

- EMF-98-015 Revision 1 With Reduced Auxiliary Feedwater Aow Page 5-77 i,

J 5.5 FSAR Chapter 14 Loss of NormalFeedwater With Offsite Power Available, One t

n90tc?-Driven AFWPtomp FaWs, Steam Dumps Enabled 1

L This event is initiated by an instantaneous loss of all main feedwater. _ Table 4.1 lists the t

initia! conditions for the transient. Table 4.2 presents the initial plant configuration for the analysis. ~ Figures' 5.65 through 5.78 show various parameters from both the primary and secondary system response. Table 5.5 presents the sequence.of events for the transient.

Following the loss of feedwater flow, there is a mismatch between primary heat i

L

. generation by the core and RC pumps and heat removal by the secondary system. This causes a primary side heatup. The resultant coolant thermal expansion causes an insurge i

irito the ' pressurizer which activates the op dy flow for a short period of time at approximately 20 seconds. A reactor trip en low SG water level occurs at 28 seconds.

The SG liquid mass inventory at the time of reactor trip is approximately 77,840 lbm. The main turbine trips automatically following the reactor trip, closing the turbine stop valves.

- The steam dump valves quick-open at approximately 29 seconds in response to post-trip RCS temperature error, then the dumps modulate to reduce and maintain RCS average l

. temperature'at approximately 532 F.

l The reactor trip and steam dump actuation initiates a temporary reduction in RCS l

temperature and coolant thermal contraction causes a decrease in pressurizer level and pressure. This level decrease initiates charging flow at approximately 53 seconds in response to the pressurizer level control system. Maximum charging flow continues until

.approximately 530 seconds and then intermittently actuates to maintain pressurizer level l

for the remainder of the transient.

l The "A" motor-driven AFW pump starts at 288 seconds (240 seconds after the AFW i

)

system actuation at 48 seconds). The single active failure is applied to the "B" motor-driven AFW pump and no flow is credited from that pump. During the period from 288 i

i seconds to 628 seconds, the flow from the "A" motor-driven AFW pump is not adequate

~to ' maintain or increase steam generator liquid inventory. However, the flow is adequate to prevent'any primary heatup. The steam-driven AFW pump actuates at 628 seconds (600 seconds after the reactor trip on low SG level). The cooling capability of the AFW system is initially constrained by the physical requirement to purge standing 435 F hot water from the active portion of the MFW piping. The purge volume is conservatively sized at 152 ft' and is not cleared until approximately 655 seconds for SG-1 and 662 seconds for SG-2.

Siemens Power Corporation Nucleer Division

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M EMF-98-015 Millstons Unit 2 Less of N:rmal Fssdwstir Flow Tr:nsisnt Revision 1 i

With Reduced Auxiliary Feedwater Flow Page 5 78 A slow decrease in steam generator inventory continues after AFW actuation. At 654

. seconds, the minimum SG liquid mass inventory of 5,540 lbm is reached in SG-1 (see figure 5.74), after which SG inventory begins to rapidly increase. Minimum liquid inventory in SG-2 is 6,458 lbm at 661 seconds, the difference from SG-1 being 4

attributable to the fact that the AFW system piping geometry favors SG-2 with a slightly higher flow rate. RCS temperatures remain relatively constant at 532 F during this period, verifying that primary to secondary heat transfer coupling is maintained and stable progress towards safe shutdown is occurring. The plant response is well-behaved throughout the transient.

The results verify that the combination of one motor driven AFW pump and the steam-driven AFW pump have adequate capacity (even with 5% degraded flow) to remove RCS sensible heat, RC purnp heat, and design basis core decay heat from the primary system, maintain RCS subcooling margin, and prevent SG dryout, provided that the low SG level reactor trip (analytical) setpoint is established at no less than 43%.

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EMF-98-015 Millstens Unit 2 Loss of NormIl FudwatIr Flow Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-79 Table 5.5 Sequence af Events for FSAR Chapter 14 LNFF Analysis with Offsite Power Available, One Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled Time (sec.)

Event O

Totalloss of Main Feedwater 20 Pressurizer Spray actuates 27.9 Reactor trip slgnal on low SG water level 28.8 Control rods begin to drop 29.9 Main Turbine trip 32 Maximum pressurizer level, 73%

38 Peak Steam Generator Pressure (993 psia) 48 AFW Actuation signal on low-low SG water level 53 Charging flow initiated in response to pressurizer level program 58 SG Blowdown isolated 288 Train "A" motor-driven AFW pump starts 628 Steam-driven AFW pump starts 654 Minimum SG liquid inventory occurs (5,540 lbm) i 1800 End of calculation

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Siemens Power Corporation - Nuclear Division

EMF-98-015 Millstana Unit 2 Lsss of N:rmal Fcidwstir Fisw Trtnsi:nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-80 120.0 C

O Reactor Power (%)

i 100.0 L

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Figure 5.65 Reactor Power, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start

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EMF 98-015

' Millstons Unit 2 L:ss of Normal Feedwater Flow Transient Revision 1 i

With Reduced Auxiliary Feedwater Flow Pege 5-81 j

i i

650.0 C

O RCS Hot Leg Temp.

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RCS Cold Leg Temp.

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Time (sec) 1 Figure 5.66 RCS Loop Temperatures, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start I

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EMF-98-015 Millst:n3 Unit 2 Loss cf N:rm:I Feedwater Flow Transient g

Revision 1 With Reduced Auxiliary Feedwater Flow Page 5 82 2600.0 C

O CNTRLVAR_630 m

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Figure 5.67 Pressurizer Pressure, FSAR Chapter 14 LNFF Analysis with Offsite Power i

Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled l

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Mi;;ston3 Unit 2 L ss cf Norm:I F01dw2t:r Fisw Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-83 100.0

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Ficure 5.68 Pressurizer Level, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start, Steam Dumps Enabled i

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EMF-98-015 Millst:na Unit 2 Less of N:rmal Faidw tir Fisw Trinsi nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-84 30.0 C

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l Figure 5.69 RCS Charging Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled l

Siemens Power Corporation - Nuclear Division

EMF-98-015 Millstona Unit 2 L:ss cf Norm:I Fiedw:t::r Flow Transient Revision 1 With Reduced Auxiliary Feedwater F5w Pagepyg 120.0 100.0 V-OOa0 0 0 a

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Figure 5.70 RCS Loop Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start, Steam Dumps Enabled Siemens Power Corooration Nuclear Division

EMF-98-015 Millstrna Unit 2 L:ss cf N:rm;l Fetdwat:r Fl:w Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-86 1 2 00.0 1140.0-C D

SG 1 C

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Figure 5.71 SG Dome Pressure, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled Siemens Power Corporation - Nuclear Division

r EMF-98-015 Millst:n) Unit 2 Less cf Norm 11 Fxdwat;r Fl:w Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-87 2 00 0. 0 1800.0 O

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Figure 5.72 SG Main Steam Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start, Steam Dumps Enabled l

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EMF-98-015 Millston) Unit 2 L:ss cf N:rman Fudwitir Flow TransiInt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-88 80.0 0

0 SG 1 70.0 C

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Figure 5.73 SG Narrow Range Level, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled t

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EMF-98-015 Millst:na Unit 2 Less cf Normal F:cdwitir Flow Transient Revisior.1

-With Reduced Auxiliary Feedwater Flow Page 5-89 5 0 0 00.0 C

D SG 1 1.iquid Moss 45000.0 C

0 SG 2 Liquid Moss 40000.0

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Figure 5.74 SG Liquid Miss inventory, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails so Start, Steam Dumps Enabled 2

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EMF 98.oi5 Mill:tona Unit 2 L:ss cf N:rnni FIMwat:r Fisw TrInsi:nt Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-90 t

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Siemens Power Corporation - Nuclear Division

EMF-98-015 Millst:ne Unit 2 L:ss cf N:rm:l Fcedwater Flow Transient l

With Reduced Auxiliary Feedwater Flow Revision 1 l

Page 5-91 100.0,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

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O SG 2 Liquid Moss 80.0 m

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l Figure 5.76 SG Auxiliary Feedwater Flow, FSAR Chapter 14 LNFF Analysis with Offsite j

l

^

Power Available, "B" Motor-Driven AFW Pump Falls to Start, Steam Dumps Enabled

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EMF-98-015 Mitst:na Unit 2 Less of N rm:I Fndw:;t:r Fl:w Transient Revision 1 With Reduced Auxiliary Feedwater Flow Page 5-92 1

40.0

.....i.....

35.0 C

D SG 1 Liquid Moss C

O SG 2 Liquid Moss m

o 30.0 o

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i Figure 5.77 SG Blowdown Flow, FSAR Chapter 14 LNFF Analysis with Offsite Power Available, "B" Motor-Driven AFW Pump Fails to Start, Steam Dumps Enabled l

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D SG 1 Liquid Mass

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Figure 5.78 SG Thermal Power, FSAR Chapter 14 LNFF Analpis with Offsite Power Available, "B" Motor Driven AFW Pump Fails to Start, Steam Dumps Enabled l

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l EMF-98-015 Mill:ttro Unit 2 Less cf Normil Fndwit:r Flow TrcnsiInt Revision 1 With Reduced Auxiliary Feedwater Flow Pago 6-1 6.

References o

1.

ANF-89-151(P)(A), ANF-RELAP Methodology for Pressurized Water Reactors:

Analysis of Non-LOCA Chapter 15 Events, May 1992.

2.

Letter, D. A. Bajumpaa (Northeast Utilities) to R. l. Wescott (SPC), " Design input for i

FSAR Chapter 14 Loss of Normal Feedwater Analysis," NE-98 SAB-018,19 Jan.

1998. [ Note: This technicalinput is recorded as M2-EV-98 0020, Rev. O in the Northeast Utilities document control system.]

3.

i Letter, G. A. Swanbon (Northeast Utilities) to R. I. Wescott (SPC), " Transmittal of Design input for FSAR Chapter 14 Small Break LOCA Analysis," NF.-98-SAB-058,2 l

April 1998. [ Note: This technical input is recorded as M2-EV-98-0070 Dev. O in the Northeast Utilities document control system.]

4.

~ USNRC Safety Evaluation related to Amendment No.139 to Facility Operating License No. DPR 65, Northeast Nuclear Energy Company et. al., Millstone Nuclear Power Station, Unit No. 2, Docket No. 50-336. (See also Enclosure 2, Letter, Mr.

l Guy S. Vissing (USNRC) to Mr. Edward J. Mroczka (Northeast Utilities), " Issuance of Amer.dment (TAC No. 68360)," dated March 20,1989.]

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