3F1011-08, ANP-3052, Rev. 0, CR-3 EPU Feedwater Line Break Analysis with Failure of First Safety Grade Trip

ANP-3052, Rev. 0, CR-3 EPU Feedwater Line Break Analysis with Failure of First Safety Grade Trip

ML11304A096
Person / Time
Site:	Crystal River
Issue date:	10/25/2011
From:	AREVA
To:	Office of Nuclear Reactor Regulation
References
3F1011-08, TAC ME6527
Download: ML11304A096 (29)

Text

ANP-3052 Revision 0 October 2011 CR-3 EPU Feedwater Line Break.Analysis with Failure of First Safety Grade Trip AREVA Inc.

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ANP-3052 Revision 0 Record of Revision Revision PageslSectionslParagraphs No. Changed Brief Description I Change Authorization 0 All Initial Release 4 4-4- 1-4-

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ANP-3052 Revision 0 Table of Contents 1.0 Introduction ........................................................................................................................................ 7 2.0 Analytical Methodology ............................................................................................................. 8 3.0 Analysis Inputs .................................................................................................................................. 9 4.0 Results / Conclusions ...................................................................................................... 12 5.0 References ...................................................................................................................................... 29 Page 3

ANP-3052 Revision 0 List of Tables Table 3-1: Input to Feedwater Line Break Analysis with First Trip Failed ............................................ 10 Table 4-1: Sequence of Events for FWLB with First Trip Failed .......................................................... 13 Table 4-2: Results for FWLB with First Trip Failed ............................................................................... 13 Page 4

ANP-3052 Revision 0 List of Figures Figure 4-1: FWLB with Fail First Trip - RCS Pressure ............................................................... 14 Figure 4-2: FWLB with Fail First Trip - Reactor Power ........................................................................ 15 Figure 4-3: FW LB with Fail First Trip - Reactivity ................................................................................ 16 Figure 4-4: FWLB with Fail First Trip - Primary System Temperatures ............. ...................... 17 Figure 4-5: FWLB with Fail First Trip - Indicated Pressurizer Level ...................................................... 18 Figure 4-6: FWLB with Fail First Trip - Pressurizer Collapsed Liquid Level ......................................... 19 Figure 4-7: FWLB with Fail First Trip - Pressurizer Surge Line Flow ...................................... 20 Figure 4-8: FWLB with Fail First Trip - RCS Volumetric Flow Rate ............................................. 21 Figure 4-9: FWLB with Fail First Trip - Pressurizer Safety Valve Flow ....................... 22 Figure 4-10: FWLB with Fail First Trip - SG Secondary Side Liquid Level ................................. 23 Figure 4-11: FWLB with Fail First Trip - SG Secondary Side Inventory ........................... 24 Figure 4-12: FWLB with Fail First Trip - SG % Operating Range ............................................. 25 Figure 4-13: FWLB with Fail First Trip - SG Pressure .................... ................................. 26 Figure 4-14: FWLB with Fail First Trip - EFW Flow ..................... ................................... 27 Figure 4-15: FWLB with Fail First Trip - Integrated MSSV Flow .......................................... 28 Page 5

ANP-3052 Revision 0 Nomenclature Acronym Definition CR-3 Crystal River Unit 3 DSS Diverse Scram System EFIC Emergency Feedwater Initiation and Control EFW Emergency Feedwater EPU Extended Power Uprate FWLB Feedwater Line Break LAR Licensing Amendment Request LOOP Loss of Offsite Power MFW Main Feedwater MSSV Main Steam Safety Valves NRC Nuclear Regulatory Commission PORV Pilot Operated Relief Valve PSV Pressurizer Safety Valve RCP Reactor Coolant Pump RCPB Reactor Coolant Pressure Boundary RCS Reactor Coolant System RPS Reactor Protection System SG Steam Generator TSV Turbine Stop Valves Page 6

ANP-3052 Revision 0

1.0 INTRODUCTION

The Nuclear Regulatory Commission (NRC) Reactor Systems Branch staff requested an additional analysis be performed to support the review of the Crystal River Unit 3 (CR-3) extended power uprate (EPU) licensing amendment request (LAR). In particular, the staff requested an analysis of the feedwater line break (FWLB) transient assuming that the first safety grade reactor protection system (RPS) trip function fails to trip the reactor. This report documents the results of the requested analysis.

The analysis documented in this report assumes that the RPS high reactor coolant system (RCS) pressure trip function fails to trip the reactor. This analysis models the non-safety grade diverse scram system (DSS) trip, which inserts the regulating control rod banks upon reaching the DSS high RCS pressure trip setpoint. The peak RCS pressure during the FWLB transient is reported and compared to an acceptance criterion of 120% of the reactor coolant pressure boundary (RCPB) design pressure (1.20

• 2500 = 3000 psig).

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ANP-3052 Revision 0 2.0 ANALYTICAL METHODOLOGY The thermal-hydraulic analysis of the FWLB analyses at the CR-3 EPU power level with the first safety grade trip failed is performed using the RELAP5/MOD2-B&W computer program (Reference [1]). The code simulates RCS and secondary system operation. The reactor Core model is based on a point kinetics solution with reactivity feedback for control rod assembly insertion, fuel temperature changes, moderator temperature changes, and changes in boron concentration. The RCS model provides for heat transfer from the core, transport of the coolant to the steam generators (SG), and heat transfer to the steam generators. The secondary model includes a detailed depiction of the main steam system, including steam relief to the atmosphere through the main steam safety valves (MSSVs) and simulation of the turbine stop valves (TSVs). The secondary model also includes the delivery of feedwater, both main and emergency, to the steam generators.

The RELAP5/MOD2-B&W code has been approved by the NRC for use in non-LOCA safety analyses (Reference [2]). The analysis documented in this report is consistent with Reference [2] except that the first safety grade trip is not credited. Instead, this analysis credits the next available trip, which is the non-safety grade DSS trip on high RCS pressure.

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ANP-3052 Revision 0 3.0 ANALYSIS INPUTS The FWLB analysis with the first safety grade trip failed uses input that is consistent with the FWLB analysis without pressurizer spray performed to support Section 2.8.5.2.4 of the CR-3 EPU LAR, with a few notable exceptions. The changes include:

1. The RPS high RCS pressure trip function is disabled.

2. The DSS high RCS pressure trip function is modeled. The DSS trip setpoint is modeled as 2465 psia. The DSS high RCS pressure trip setpoint includes margin to bound possible changes in the containment pressure during a FWLB. The DSS trip delay time is modeled as 1.23 seconds.

Finally, the rod worth available to the DSS system is modeled as only 2.0 %Ak/k, since the DSS system only inserts the regulating control rod groups.

Table 3-1 summarizes all of the key input to the FWLB analysis with the first safety grade trip failed, including the changes highlighted above.

The peak RCS pressure is reached shortly after reactor trip before any active components such as emergency feedwater (EFW) are credited to mitigate the results. Therefore, there are no single failure assumptions that would result in a more limiting peak RCS pressure. However, the FWLB overpressure protection analysis with the first safety grade trip failed assumes the same single failure assumption as the FWLB analysis performed to support Section 2.8.5.2.4 of the CR-3 EPU LAR. The single failure assumption modeled is the failure of one train, of Emergency Feedwater Initiation and Control (EFIC) such that EFW flow is not initiated automatically in one train. Consequently, only one of the two EFW pumps is assumed available to provide flow to the SGs. This single failure assumption produces a conservative long-term transient response after EFW is assumed to reach the SGs.

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ANP-3052 Revision 0 Table 3-1: Input to Feedwater Line Break Analysis with First Trip Failed Parameter Value RCS Conditions Core Power, MWt 3014

• 1.004 = 3026.1 Decay Heat 1.0*ANS71 plus B&W Actinides Total Net Reactor Coolant Pump (RCP) Heat, MWt 16.4 Average RCS Temperature, °F 582 Initial Hot Leg Pressure, psia 2170 Total RCS Flow Rate, gpm 374,880 Pressurizer Initial Indicated Pressurizer Level, in 240 Pressurizer Spray Not Modeled Pressurizer Heaters Not Modeled Pilot Operated Relief Valve (PORV) Not Modeled Pressurizer Safety Valve (PSV) Setpoints, psig 2500 * (1 + 0.03) (open) 2500 * (1 - 0.04) (close)

Total PSV Rated Capacity, Ibm/hr 2

• 317,973 @ 2750 psig Secondary Side Initial Main Feedwater (MFW) Temperature, OF 460 OF Tube Plugging, % 5 Initial SG Level, %OR < 70 EFW Temperature, OF 120 EFW Minimum Required Flow, gpm 550 EFW Delay Time, sec 60 Turbine Trip Delay Time, s 0.0 TSV Stroke Time, s 0.2 Number of Main Steam Safety Valves (MSSVs) per SG 8 MSSV Capacity per SG 7 @ 845,759 Ibm/hr 1 @ 583,574 Ibm/hr MSSV Nominal Setpoints 2 @ 1050 psig 2 @ 1070 psig 2 @ 1090 psig 2 @ 1100 psig including small MSSV MSSV Setpoint Tolerance +3%

MSSV Accumulation +3%

MSSV Blowdown -5%

Core Kinetics Parameters Doppler Temperature Coefficient (Ak/k/°F) -1.30 E-5 Page 10

ANP-3052 Revision 0 Parameter Value Moderator Temperature Coefficient (Ak/°kIF) 0.0 E-4 Prompt Neutron Generation Time, (ps) 24.8 Effective Delayed Neutron Fraction 0.0070 DSS Insertable Rod Worth, %Ak/k 2.000 RPS High RCS Pressure Trip Assumed Failed DSS High RCS Pressure Trip Setpoint, psia 2465 DSS Trip Delay Time, s 1.23 Miscellaneous Offsite Power Available Single Failures One Train of EFIC Operator Actions None Page 11

ANP-3052 Revision 0 4.0 RESULTS I CONCLUSIONS The sequence of events for the FWLB accident with the first safety grade trip failed is listed in Table 4-1 and the calculated results are tabulated in Table 4-2. Plots that demonstrate the transient response following a FWLB are provided in Figures 4-1 through 4-15.

The transient progression is similar to the FWLB transient described in Section 2.8.5.2.4 of the CR-3 EPU LAR. The trip setpoint is reached at 9.025 seconds instead of 8.802 seconds because the DSS high RCS pressure setpoint is higher than the RPS high RCS pressure setpoint. In addition, because the delay time modeled for the DSS trip is longer than the delay time associated with the RPS, control rod insertion does not begin until 10.258 seconds compared to 9.415 seconds in the FWLB analysis in LAR Section 2.8.5.2.4. The longer time to reactor trip contributes to a higher peak RCS pressure. The peak RCS pressure is also higher for the analysis with the first safety grade trip failed because DSS only inserts the regulating control rod banks, and therefore has less inserted rod worth than the analysis modeling the RPS trip function.

The peak RCS pressure (2950.9 psia) occurred in the lower downcomer region of the reactor vessel and did not exceed 120% of the RCPB design pressure of 2500 psig (3000 psig).

As explained in Section 2.8.5.2.4 of the CR-3 EPU LAR, the FWLB event is sufficiently severe that the pressurizer fills., As a result, the PSVs begin to pass single-phase liquid. The PSVs of the type installed at CR-3 achieve satisfactory performance for fluid temperatures greater than -550'F. An additional check is performed to show that the PSV fluid inlet temperature remains greater than 600 OF to ensure that the PSVs operate as intended. Figure 4-4 demonstrates that at all times throughout the FWLB transient, the liquid temperature at the top of the pressurizer remains above 600 OF.

A sensitivity study was performed modeling the FWLB transient with the first safety grade trip failed and a loss of offsite power (LOOP). The LOOP is conservatively considered to occur coincident with the turbine trip that follows reactor trip. The case with a LOOP included the insertion of the safety control rod banks on LOOP. The sensitivity study determined that the peak RCS pressure from a LOOP case (2921.9 psia) is less limiting than the peak RCS pressure without a LOOP. Therefore, the FWLB evaluation using the DSS trip function and no LOOP is the bounding case.

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ANP-3052 Revision 0 Table 4-1: Sequence of Events for FWLB with First Trip Failed Parameter Time, sec Transient Initiated 0.0 MFW to both SGs Interrupted 1.OE-6 EFIC Actuated on Low SG-B Level 6.515 Peak Thermal Power Occurs 6.523 DSS High RCS Pressure Trip Setpoint Reached 9.025 Regulating Control Rod Groups Begin to Insert 10.258 Turbine Trip, TSVs Begin to Close 10.260 Initial PSV Lift -12 Peak RCS Pressure occurs 13.518 Affected SG depressurization complete -36 EFW to Unaffected SG Begins 66.520 Final PSV closure -282 Peak Tave occurs -404 Transient Analysis Ends 600 Table 4-2: Results for FWLB with First Trip Failed Parameter Value Peak RCS pressure (psia) 2950.9 Peak thermal power (%RTP) 100.49 Peak Tave (OF) 630.54 Page 13

Figure 4-1: FWLB with Fail First Trip RCS Pressure 3000

-- Hot Leg 1 (CV 110-4)

-- Hot Leg 2 (CV 210-4)

-A Core Exit (CV 352-01)

.... .< Top of PZR (CV 405-01)

-v Lower RV Downcomer (CV 324-04)

I--------------------

---

I -------------

cdl ..........

crn C0 0O 420 480 540 600 Time (s)

I

Figure 4-2: FWLB with Fail First Trip Reactor Power 3200 --- Total Reactor Power (CVAR 370)

-- Thermal Power (CVAR 379) 20------------------

24 I--------------------

0-.-------........................ ....

. . . . . . . -------- r-------

10- I--------- ---------------- --

800 0 60 120 180 240 300 360 420 480 540 600 Time (s)

_2

Figure 4-3: FWLB with Fail First Trip Reactivity 0.010 0.000

-0.010

-0.020 0

-0.030

-0.040

ý CDo

-0.050 S0 0 300 Time (s) 3

Figure 4-4: FWLB with Fail First Trip Primary System Temperatures 720

-- RCS Ave Temp (CVAR 900)

-o Loop 1 Hot Leg (CV 110-4)

Loop 2 Hot Leg (CV 210-4) 700......... - 7v Loop Loop IA 1 B ColdCold Leg Leg (CV 160-4)

(CV 180-4)

Loop 2A Cold Leg (CV 260-4)

-+ Loop 2B Cold Leg (CV 280-4) 680 .................. - x Top of Pressurizer Liquid Temperature (CV 405) ------------------

660 --- ..... ... ...........

S660 -- -- ----........

--- ...... ..............--..............--... ......................... I-------------------

cl) 60 -- - - - - -- -- -- - - - - -,-- - . . .. . . -- - - i . . ... ...-- m '- :k---

-- - - - -- -- - .^ -, -- --- - -- - - - - -

545 .......----.----- .---- .---. I..-- .. -....

520 0= 0W 0 60 120 180 240 300 360 420 480 540 600 0 to Time (s)

_4

First Figure 4-5: FWLB with -Fail First Trip Indicated Pressurizer Level Level 400 Pressurizer Indicated with.Fail FWLB 4-5:

Figure I- CVAR 409. I 380 ............ --------------

360 ---------------..........------------------ I............ ----------- .......... .............

340 ............ ........................ ...........------------

_m _m PPRRERR 2RRRMMnPRPMRRR ---- ----------

RPPRRPRRRRRSýý ý=mmm"m=

320 -------------------- ---- ------------ -- ---- ---------- .............. -----------------

................ i 300 ............ ---------------- ---------------- --------------------- ----------------- --------------  :---------------

• 280 260 ------------------ .............

240 ------------ ------------- ------------------ ----------- -------------- -------------_

220 ------------ ---------------- ------------------ -------------- --- ----------- -------------- -------------------

200 0 U 60 120 180 240 300 360 420 480 540 600 Time (s)

_5

Figure 4-6: FWLB with Fail First Trip Pressurizer Collapsed Liquid Level 44 IICVAR 325 I 42 40 -------------------------------------------------- ---------------------------- ----------------------------- ------------------

38 -----------------

36  :-------------------

34 ---------------------------------------------

---

------------------- I:--------

-o 32 -------------------------------------

---

-------------------------- ------------------- -------------- --------------- L--------------

30 ----------------

28 ................

---

------------- I .................. -------- ---------------- --------- ------------------------------- ------------------

26 ................ ------------------

I-------------------- - ---------------------------- ----------------------------- ------------------

24 oLA t"0 0 60 120 180 240 300 360 420 480 540 600 Time (s)

_6

Figure 4-7: FWLB with Fail First Trip Pressurizer Surge Line Flow 500 250 ------------------- --------------------------------------

-250 ...................------

C

-500

-750 .1.1.'..... --------------------------.....

-1000 I--------

-1250 ------------------- -------

-1500 S0 0 60 120 180 240 300 360 420 480 540 600 Time (s) t0

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Figure 4-8: FWLB with Fail First Trip RCS Volumetric Flow Rate 400000

- aCVAR 332R 350000 .................. ------- ---------------------------- ...................... -----------------------------

300000 .................. ------- ----------- ----------------

250000 ------------------ ------- ...........

I...................

0 200000 - --------------------- ------------

U 1500001 . ----------- ................ ---------------- .........................................

100000 1. ................. ----- --- ---

50000 ................---------------------------- --------------------------------------

ýo ý 0 0 0j 0 60 120 180 240 300 360 420 480 540 600 Time (s) 8

Figure 4-9: FWLB with Fail First Trip Pressurizer Safety Valve Flow with .FailFlow Valve First Trip 500 Safety FWLB Figure 4-9: Pressurizer mflowj-492000000 450 ............... .......................................------------------------------- ------------------

400 ................ -------------------- -------------------------------------------------- ..............

350 300

-1 0 250 ---------- ......... -----------------------------------

200 il . .......-.-..--.-.-.-...-- ............. I--------------------

150 1ý 100 --------------------.................. ----------------

50 .----- .............. ... --- ----------------------------------

CDo ý 0 0 0-120 180 240 360 420 480 540 Time (s)

_9

Figure 4-10: FWLB with Fail First Trip SG Secondary Side Liquid Level 12 - q 9 10 1 ---

I------------- ------------

8 -----------

au

-V--- .......- -----------------------------

6 ----------------- .........

Cn 4 --------------------------------

Ct2

---

----------------- B--------------- -----------

2 ----------- ................

0 - @ 0 9 0 9 @ @ e. 0 0 8 @ @ 0 @ @-."- v ow 0 60 120 180 240 3T0 360 600 CDQ Time (s)

I0

Figure 4-11: FWLB with Fail First Trip SG Secondary Side Inventory, Ibm 80000 I

--- SG-A (CVAR 607)

-o SG-B (CVAR 707) 70000 1------------- -----------

60000 1- ------------------

S 0 5 00 00. 1 . . . . . . .. . . . . . . . .. . . . . . . . . . .. . . . . . . . . -------------------

---

I ---------

---

------------------------- I ------------------

I-----------------------------------------

-o 40000 -----------------.. . ---------------- I.........-----------------------------

I ..................

c-I 0 30 000 -.................... I------------------------------------------------------------------------------

C/I 0Ct2 20000 --- --------- ---- ---- --------------- -----.....................

10000 ...... ------------------- ..................

p-o 0 0 00 180 240 300 360 420 480 540 600 C

Time (s) 11

Figure 4-12: FWLB with Fail First Trip SG % Operating Range 1oo

-- SG-A (CVAR 612)

-- i SG-B (CVAR 712) 90 ..................... -------------- v.......... ------- . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . ..................

80 --------------------- ---------- ........----------------- .......

704- .....................

60 --------------  : ---------------- ------------- .......

C 50 ............------------------ I--------------- -- ------- -----

0#

40 ------------ .......... I----------------- ------

30 -----------.................. I-----------------

20 1--I---. ............ ---------------- --------------- ............. I--------------- --------------

10 ---------- --------- - - - -- ------------------ ------------------ - ----------- ------------------- -------------

0 4  % s ~ if 4 l --- , MmfMW RRa99 3R SH1 " .H-- - --- Hea a e * -i~ 00 0 60 120 180 240 300 360 420 480 540 600 0.Q Time (s)

CD/

12

Figure 4-13: FWLB with Fail First Trip SG Pressure, psia 1200

-- n Unaffected (CV648-1)

-* Affected (CV 748-1) 1100 .- "

1000 ----

100 0 --- .----- .

---

-----------.--------- --------- .------- ...........I .---------- -------.------------ -- .-- .---------------

90 080 -------- --- --------------------------------- - - - - - - - - - - - - - - - ----

50 0 ---.-------------- ..-------

400 ......................... . .... .... .......

---

...--- I..--

400 20 o -- . .

0 60 1.20 180 240 300 360 420 480 540 600 Time (s) 13

Figure 4-14: FWLB with Fail First Trip EFW Flow 100

--s To Unaffected SG (JUN 626)

--- To Affected SG (JUN 726) 90 -------------

80 70 .......... ----------------

I 60 ----------- ----- ---------------- ----- ----------------------------------------------- -----------------------

0 50 . ......... ----------------------

40 --------------- - -- ------------ ----- - ------------- -

30 ----------- ---------------------- .7 ------------------ ------------ -----------------------

20 ----------- ----------------- ... ------------------ --------.......... -------............ ---------------.......

10 ----------- --- - ----------- ... ... ---------- ---------- -------- ---------------------

01 -- j 0 0,0 0-- - 1 0 0 0 0 1ý 0 0-0 0 ý 0 - I.- - 0 0 0 0 0 0 0 0. 0 W A A R A @ - , - - - 0.0 0P 60 120 180 240 300 360 420 480 540 600 Time (s)

-.1 14

Figure 4-15: FWLB with Fail First Trip Integrated MSSV Flow 100000

-- Unaffected SG (OVAR 659)

,-- Affected SG (CVAR 660) 90000------------------------------------------------------------------- ------------------

7 0000 . . . . . . . .. . . . . . . . . .. .. --.-------------------

80 000 - - -- - - - - --

70000 ---- -

360000- -- . .. . . .. . . . .. . . .. . . .. . . .. . .--..

C

-Er 200050000--------------- ----- 1 -------------------------

10000

.* o. . o 0 60 120 180 240 300 360 420 480 540 600 0 Time (s)

.t0 15

ANP-3052 Revision 0

5.0 REFERENCES

1. BAW-10164PA-06, "RELAP5/MOD2-B&W - An Advanced Computer Program for Light Water Reactor LOCA and Non-LOCA Transient Analysis."

2. BAW-10193PA-00, "RELAP5/MOD2-B&W for Safety Analysis of B&W-Designed Pressurizer Water Reactors."

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