ML18064A590

Non-Proprietary Palisades Loss of Load Analysis.

ML18064A590
Person / Time
Site:	Palisades
Issue date:	10/19/1994
From:	Cole S SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER
To:
Shared Package
ML18064A583	List: ML18064A582 ML18064A584 ML18064A590
References
EMF-93-086(NP), EMF-93-86(NP), NUDOCS 9502010248
Download: ML18064A590 (24)

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Siemens Power Corporation - Nuclear Division EMF-93-086(NP)

Issue Date: ~0/19/94 Palisades Loss of Load Analysis Prepared by:

S. E. Cole PWR Reload Analysis PWR Nuclear Engineering April 1993 skm

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CUSTOMER DISCLAIMER IMPORTANT NOTICE REGARDING CONTENTS ANO USE OF THIS DOCUMENT PLEASE READ CAREFULLY Siemens Power Corporation's warranties and representations concerning the subject matter of this document are those set forth in the Agreement between Siemens Power Corporation and the Customer pursuant to which this document is issued. Acccrdingly, except as otherwise expressly provided in such Agreement, neither Siemens Power Corporation nor any person acting en its behalf makes any warranty or representation, expressed or implied, with respect to the accurac'/, completeness, or usefulness of the information contained in this document, or that the use of any information, apparatus, method or process dlsdosed in this document will not infringe privately owned rights; or assumes any fiabffitles with respect to the use of any information, apparatus, method or process dlsdosed In this document.

The information contained herein is for the sole use of the Customer.

In order to avoid impairment of rights of Siemens Power Corporation in patents or inventions which may be induc!ed in the information ccntained in this document, the recipient, by its acceptance of this document, agrees not to publish or make public use Qn the patent use of the term) of such information until so authorized in writing by Siemens Power Corporation or until after six (6) months following termination or expiration of the aforesaid Agreement and any extension thereat, unless expressly provided In the Agreement No rights or licenses in or to atrf paten1S are implied by the furnishing of this document

SIEMENS i EMF-93-086(NP) .

~ .

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Palisades Loss of Load Analysis October 1994 Siemens Power Corporation Nuclear Division

( '

EMF-93-086(NP)

Page ii Table of Contents Section 1.0 EVENT DESCRIPTION .................................. : . . . . . . . . . . 1-1 2.0 DEFINmON OF EVENTS ANALVZED ........*.....*................... 2-1 3.0 ANALYTICAL METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 4.0 ANALYSIS RESULTS * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

5.0 CONCLUSION

. * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

6.0 REFERENCES

. * * * * * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

EMF-93-086(NP)

P~ge iii List of Tables Table Page 4.1 Event Summary for the Loss of External Load Event . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

EMF-93-086(NP)

Page iv List of Figures Figure 3.1 ANF-RELAP Loss of External Load System Nodalization . . . . . . . . . . . . . . . . . . . . . . 3-2 4.1 Reactor Power for Loss of External Load-. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 4.2 Core Average Heat Flux for Loss of External Load . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4 4.3 Pressurizer Pressure for Loss of External Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 4.4 Pressurizer Liquid Volume for Loss of External Load . . . . . . . . . . . . . . . . . . . . . . . . . 4-6 4.5 Primary Coolant System Mass Flow Rate for Loss of External Load . . . . . . . . . . . . . . 4-7 4.6 Primary Coolant System Temperatures for Loss of External Load . . . . . . . . . . . . . . . 4-8 4.7 Reactivity for Loss of External Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9 4.8 Secondary Pressure for Loss of External Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 O 4.9 Steam Generator Secondary Fluid Mass for Loss of External Load . . . . . . . . . . . . . 4-11

EMF-93-086(NP)

Page 1-1 Loss of External Load With 25% Steam Generator Tube Plugging 1.0 EVENT DESCRIPTION A Loss of External Load event (Event 15.2.1) is initiated by either a loss of external electrical load or a turbine trip. Upon either of these two conditions, the turbine stop valve is assumed to rapidly close (0.1 second). Normally, a reactor trip would occur on a turbine trip; however, to calculate a conservative system response, the reactor trip on*turbine trip is disabled. The steam*

dump system (atmospheric dump valves - ADV's) is assumed to be unavailable. These assumptions allow the Loss of External Load event to bound the consequences of Event 15.2.2 .

(Turbine Trip - steam dump system unavailable) and Event 15.2.4 (Closure of both MSIV's - valve closure time Is> 0.1 second).

The Loss of External Load event primarily challenges the acceptance criteria for both* primary and secondary system pressurization and DNBR. The event results in an increase in the primary system temperatures due to an Increase in the secondary side temperature. As the primary system temperatures increase, the coolant expands into the pressurizer causing an increase in the pressurizer pressure. The primary system is protected against overpressurization by the pressurizer safety and relief valves. Pressure relief on the secondary side Is afforded by the steam line safety/relief valves. Actuation of the primary and secondary system safety valves limits the magnitude of the primary system temperature and pressure increase.

With a positive BOC moderator temperature coefficient, Increasing primary system temperatures result In an Increase In core power. The increasing primary side temperatures and power reduces the margin to thermal limits (i.e., DNBR limits) and challenges the DNBR acceptance

• criteria.

EMF-93-086(NP)

Page 2-1

• 2.0 DEFINmON OF EVENTS ANALVZED The objectives In analyzing this event are to demonstrate that the primary pressure relief capacity is sufficient to limit the pressure to less than 11 0% (2750 psla) of the design pressure and that the secondary side pressure relief capacity is capable of limiting the pressure to less than 11 0%

(1100 psia) of design pressure. A steam generator tube plugging level of 25% is assumed for the analysis. No credit Is taken for direct reactor trip on turbine trip, the turbine bypass system or the steam dump system. Also, credit from the pressurizer PORV's is conservatively excluded from this analysis. In general, the parameters and equipment operational states are selected to maximize the system pressure.

A loss of load event also challenges thermal margin limits. However, Reference 1 disposed this subevent as being bounded. by other more limiting AOC events. Thus, the DNBR for this event Is not evaluated.

The Loss of External Load Is credible only for rated power and power operation events because there Is no load on the turbine at other reactor conditions. The rated power conditions bound the consequences for other reactor power operating conditions because of the increased stored energy. The higher the stored energy in the primary system, the more severe the consequences of this event.

........ -1.0

~

+I

..,J u

. tU cu -2.0

~

-3.0 m

s:

"Tl I

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 <O

(.>

"lJ Time (sec) II> 0 co I

O>

(t) .2?.

~z co,]!

Figure 4. 7 Reactivity for Loss of External Load

1000.0 Cd rn ii.

900.0 Cl>

=='

rn rn 800.0

~

G>

700.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 Time (sec)

I L_,__

Figure 4.8 Secondary Pres for Loss of External Load

140.0 CJ Q)

~

e

..a Q) 130.0

<<S

~

~

- 0 rs..

rn rn 120.0 as

.s 110.0 0.0 2.0 4.0 8.0 8.0 10.0 12.0 14.0 18.0 18.0 20.0 Time (sec)

Figure 4.5 Primary Coolant System Mass Flow Rate for Loss of External Load

Average o---o Cold Leg

• Hot Leg 825.0 x x Core Inlet ra...

cu

~ 800.0 *------------*~.

e .~

f! 5?6.0

.3cd cu

~

8 560.0

, ___.....=:::::=---------

526.0

~ I 500.0 L-.l-&.._ _ _._....._.&...-<.........-a..--_._____.__..._.._._____...._.._..........-a.._,__.___..._.&...-<.........-L-'--'--'--'-.&......L-.1--'

0.0 2.0 4.0 8.0 8.0 10.0 12.0 14.0 18.0 18.0 20.0 Time (sec)

• Figure 4.6 Primary Coolant System ratures for Loss of External Load

2500.0 2400.0 rn Po.

......... 2300.0 G>

L.

~

rn 2200.0 rn G>

0..

2100.0 2000.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 Time (sec)

Figura 4.3 Pressurizer Pressure for Loss of External Load

1100.0 n

.a 1075.0 Q) 1050.0 8

• ='

0 1026.0 "C

='

.....a4

..:a 1000.0 976.0 m

960.0 L-.L-L.-'-_._..._.L......L_.__.__._..._.L......L_.__.__._._.L......L_._....._.........._L-l-l......L..-'-..1-.&-IL......L-L.-l-....L.....L....L-1-1.-1 ~

"Tl 0.0 2.0 4.0 8.0 8.0 10.0 12.0 14.0 1.8.0 18.0 20.0 cb

(,.)

"tJ I Time (sec) P> 0

• Figure 4.4 Pressurizer Uquld .e for Loss of External Load*

co m-

~

<D ..........

-to- z

-u .

2400.0

'Z' 2000.0

!ii::

s QJ 1'o 1600.0 0

~

...0 1200.0

~

CJ QJ

~ 800.0 400.0 m

s::

"Tl cb o.*o 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 "lJ I w

Time (sec) P> 0 cc OJ a>~

~z

<.> .]!

Figure 4.1 Reactor Power for Loss of External Load

N

~

..... 16.0 I

s..

.d

~

,,0

....... 12.0 H

-:s rz.

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<<S cu 8.0

I:

cu bO

< 0 cc CX>

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Figure 4.2 Core Average H - for Loss of External Load t -~. - '

EMF-93-086(NP)

Page 4-1 4.0 ANALYSIS RESULTS The maximum primary pressurization case initiates with a rapid closure of the turbine stop valve in 0.1 seconds. Steam line pressure increases until the safety relief valves open at 10.55 seconds. The maximum pressure in the steam generators of 1040.8 psia is achieved at 13.80 seconds. The maximum required steam line relief valve flow capacity to control the secondary-side pressure Is about 3.8 Mlbm/hr.

The pressurization of the secondary side results in decreased primary to secondary heat transfer, and a substantial rise in primary system temperature. A primary coolant temperature increase of about 15.1 °F has occurred by 9.50 seconds. This results in a large insurge into the pressurizer, compressing the steam space and pressurizing the primary system. The reactor trips on high pressure with rods beginning to insert at 7.25 seconds, and the pressurizer safety valves open at 10.80 seconds. The increase in coolant temperature also causes the core power to rise to 2671.2 MWt due to positive moderator feedback. The transient is terminated shortly after reactor scram due to decreasing primary coolant temperature and pressure.

The capacity of one valve is enough to contain the pressurizer pressure to a maximum of 2575.9 psia. The maximum primary system pressure is 2614.9 psia occurring at 10.90 seconds. The maximum PCS pressure is less than the 2750 psia limit. The responses of key system variables are given in Figures 4.1 to 4.9. The sequence of events is given in Table 4.1.

The secondary side pressure relief valves contain sufficient capacity to limit the pressure to less than 11 0% (1100 psia) of design pressure.

L

EMF-93-086(NP)

Page 4-2 Table 4.1 Event Summary for the Loss of External Load Event Event Value Time (sec}

Turbine Trip 0.00 Pressurizer Heaters on 0.00 Charging Flow on 133 gpm 0.00 2 0.10 Peak Core Average Heat Flux 168,830 Btu/hr-tt Reactor Scram (High Pressure) 7.25 Peak Power Level 2671.2 MWt 7.90 Steam Line Safety Valves Open 10.55 Pressurizer Safety Valves Open 10.80 Peak PCS Pressure 2614.9 psia 10.90 Peak Core Average Temperature 584.74 °F 11.85 Peak Steam Generator Pressure 1040.8 13.80

---1

EMF-93-086(NP)

Page 3-1

• 3.0 ANALYTICAL METHODOLOGY ANF::-RELAP was used in accordance with Siemens Power Corporation's approved _methodology (2). The ANF-RELAP nodalization used In the Loss of Load model is given in Figure 3.1 .

Figure 3.1 ANF-RELAP Loss of External Load System Nodallzatlon *

• ~. .. * *

,ll rn 13.0 flJ Cd

s 12.0 m

s::

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 cb "ti (..)

Time (sec) p) co CD 0

I CX>

O>

-tz

_.._"ti Figure 4.9 Steam Generator Secondary Fluld Mass for Loss of External Load

EM F-93-086(N P)

Page 5-1

5.0 CONCLUSION

The maximum pressurizer and secondary side pressure remain below 110% of design pressure.

Applicable acceptance criteria for the event are therefore met.

EMF-93-086(NP)

Page 6-1

6.0 REFERENCES

1. EMF-92-178. *Siemens Power Corporation Nuclear Division Palisades Cycle 11:

Disposition and Analysis of Standard Review Plan Chapter 15 Events,* December 1992.

2. ANF-89-151 CPlCAl. *ANF-Relap Methodology for Pressurized Water Reactors: Analysis of Non-LOCA Chapter 15 Events,* April 1992.

EMF-93-0BS(NP)

Issue Date: 10; 19; 94 PALISADES LOSS OF LOAD ANALYSIS Distribution J. W. Hulsman CPCo/H. G. Shaw (6)

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