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Specs for Mist Continuous - Venting Tests
	ML20203M020
Person / Time
Site:	Davis Besse
Issue date:	08/21/1986
From:	; TOLEDO EDISON CO.
To:	;
Shared Package
ML20203M018	List: ML20203M015; ML20203M020;
References
	PROC-860821, NUDOCS 8609020164
	Download: ML20203M020 (128)
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I SPECIFICATIONS FOR THE MIST CONTINUOUS-VENTING TESTS I 8609020164 860021 PDR ADOCK 05000346 I P POR

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SPECIFICATIONS FOR TF.E MIST CONTINUOUS-VENTING TESTS m _ _

TABLE OF CONTENTS enae I

1.0 INTRODUCTION

.............................................. 1-1 L 2.0 CH ARACTERIZ ATION, TEST 3 70'0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.1 Purpose .............................................. 2-1 2.2 Outline .............................................. 2-1

{ 2.3 Conduct .............................................. 2-2

3.0 NATURAL CIRCUL ATION COOL DOWN, TEST 3 701 . . . . . . . . . . . . . . . . . . . 3-1 3.1 Purpose .............................................. 3-1 3.2 Description .......................................... 3-1 3.3 Conduct .............................................. 3-6 3.3.1 Pre-Test Steady State ...................... 3-6 3.3.2 Initiation ................................. 3-7 3.3.3 Control During Testing ..................... 3-7 3.3.4 Te rm i n at i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9 3.3.5 .

Measurements ............................... 3-9 3.3.6 Acceptance Critoria ........................ 3-10 4.0 . SBLOCA WITH NONCONDENSIBLES, TEST 3702 .................... 4-1 4.1 Purpose .............................................. 4-1 4.2 Description ..................................... 4... 4-1 4.3 Conduct .............................................. 4-3 4.3.1 Steady-State Protest Conditions ............ 4~-3 .

L 4.3.2 Initiation ................................. 4-3 4.3.3 Control During Testing ..................... 4-5 4.3.4 Te rm i n a t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

[ 4.3.5 d.3.6 Measuromonts ...............................

Acceptance Critoria ........................

4-7 4-7 5.0 THE THIRD PH ASE OF HPI-PORY COOLING, TEST 3703 . . . . . . . . . . . . 5-1 5.1 Purpose .............................................. 5-1 5.2 Description .......................................... 5-1 5.2.1

{ 5.2.2 Predicted Events ........................... 5-1 MIST Initi al Conditions . . . . . . . . . . . . . . . . . . . . 5-2 5.3 Conduct .............................................. 5-4

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6.0 REFERENCES

................................................ 6-1 APPENDICIES A Co nti n uou s Ve nt L i ne Pe rf o rma nce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1 B Extracts Of Performanco Pred iction s . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-1 C Predicted LOFW Transient ....................................... C-1 D MIST Simulation of Davis Bosse Charactoristics, Test 3703 ...... D-1 1

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I List Of Tables

[ 2.1 Characterization Conditions ............................... 2-11 3.1 - 3.3 Natural Circulation Cooldown, Test 3701 lE 3.1 Initial Conditions ....................................... 3-11 J 3.2 Initiation ............................................... 3-13 3.3 Co n t rol D u r i n g Te st i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14 I ,4.1 - 4.3 SBLOCA With Noncondensibles, Test 3702 4.1 Initial Conditions ....................................... 4-9 4.2 Initiation ............................................... 4-11 4.3 Cont rol D u r i n g Test i ng . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12 5.1 - 5.5 HPI-PORY Ceoling, Test 3703 5.1 Predicted Events ......................................... 5-8 5.2 Plant and MIST Conditions ................................ 5-9 5 5.3 I n i t i al Co n d i t i o n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10 .

5.4 I n i ti at i on O f Test 3 703 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11 5.5 Control During Testing ............ ...................... 5-12 A.1 CVL Configuration ......................................... A-13 A.2 Logic used To Determine CVL Performance ................... A-15 A.3 Code Listing .............................................. A-16 A.4 Description Of Cases ...................................... A-20 C.1 Sequence Of Events ........................................ C-7 I D.1 0.2 D.3 M I ST Co r e Pow e r , Te s t 3 7 0 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-6 HFI & MU (Test 3703) ......................................

MIST Cr it i cal-Fl ow Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-8 D-7 List of Fiouros 2.1 Heat Loss Vs Temperature .................................. 2-12 I 3.1 A.1 A.2 Estima ted Prima ry Fl ui d Tempe ratu res . . . . . . . . . . . . . . . . . . . . . . 3-15 RVUH Cooldown Rate (Plant Configuration)

Two Predictions of Plant CVL Flowrate

.................. A-21 I A.3 (50 F/h S /stem Cooldown)

Two Predictions of Plant CVL Flowrate (20 and 25 F/h Cooldowns) .................................

A-22 A-23 A.4 CVL Flowrates (Various Configurations) .................... A-24 A.5 RVUH Co ol d ow n Ra t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25 C.1 - C.ll Coda Predictions ...................................... C ........................................................... C-18

,g D.1 Power..................................................... 0-9 3 0.2 HPI and Makeup ............................................ D-10 0.3 MIST HPI and MV ........................................... D-11 I

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1.0 INTRODUCTION

MIST will be modified to include a simulation of the Davis Besse continuous

. vent line (plus instruments to measure temperature, level and flowrates in the line). Both the MIST and plant continuous vent lines (CVLs) are without valves (i.o., in continuous operation) and ex' tond from the reactor vessel upper head to a stcam generator inlet plenum. Whereas the plant CVL connects to the A steam generator (in the loop containing the pressurizer), ,

the MIST CVL connects to the B-SG, primarily to take advantage of the a onhanced instrumentation afforded by this newer of the two model SGs. The CVL tests are specified heroin.

The plant CVL is predominantly 2 1/2-ir.chos in diameter, the MIST CVL is 1/2-inchos in diamotor. The model CVL was kept rather large, rather than ccaling it based on model system power or volume, to preserve two-phase flow behavior as well as liquid-liquid counterflow. The model CVL thus has much more fluio and metal mass tnan would a model CVL tealed based on core L

power level. Also, without guard heating, the model CVL would have.much larger losses to ambient than the scaled plant CVL losses.

L The model CVL is to be guard heated using a single zone of guard hesting.

Rather than guard heating to offset all the model CVL heat lossos, roughly ton porcent of the heat losses without guard. heating must be retained.

The ef fects of these CVL heat losses, in both the model and the plant, are explorod in Appendix A.

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1-1 r

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il The model CVL guard heater control will be determined and tested in a characterization test, Section 2. Having set the model CVL guard heaters, the performance of the CVL will then be determined in two tests: a natural ci rcul ation cool d ow n , and a post-SBLOCA transient with

, noncondensibles. These tests are specified in Sections 3 and 4.

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! Section 5 specifies a test of HPI-PORY (feed and bleed) cooling during which core-generated steam flows directly to the pressurizer. Appendix C provides the predictions of a LOFW (loss-of-feedwater) transient which involves such HPI-PORY cooling. Appendix D describes the MIST boundary systems for Test 3703. References 1 through 6 provide descriptions of the

!' plant and MIST vent lines.

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e b 2.0 CHARACTEEI M TION (TEST 3700)

Purnose

!' 2.1 l The' pr'imary purpose of the CVL characterization test is to determine the l 4 !

optimam CVL guard heater s'ett'ngh, and the variations of this CVL guard L

-; heator control bias with tem 9erature. CVL performance during steady state, loop cooldoma, and with a'voicad reactor vessel upper head (RVUH) are also 6 ' '

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obtained. -

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2.2 Out1 i n.a V

The C/L characterization test consists of a series of determinations and I adjustments at two (hat leg) flu.j! temperatures. .

These settings and hot l, ^ 1eg teaperatures are If sted in Table 2.1.

[( ' ' Figure 2.1 illustrates heat less ve rsu s (hot leg) fluid temperature

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c (obse rved i n 'GERD A) . The variation of heat loss with temperature is t

roughly linear above 400F, tiu t it is highly non-linear at lower temperature. (the loss, and variation of loss with temperature, are both l.' '

expected to be approxistely zero as the fluid temperature approaches the ar.b i e nt temperature). Based on this variation of heat loss with

( 9 temperature, determinations at two temperatures above 400F define the slopo in -this region. Th's loss-versus-temperature characteristics near the q , ambient ( ten.perature can be included to estimate,' the loss over the entire

,f- i range of .temperatu; es.

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k Three steps are used to set the CVL guard heater at each temperature, then a fourth step is used to revise the loop conditions toward those of the {

next setting. The three steady-state steps are: -

r-k 1. Deterwine CVL heat losses without guard heating, by fluid energy balance.

( 2. Determine the total guard hester power required to offset the CVL heat l

losses.

(

3. Determine the optimum CVL heat loss, the guard heater input power needed to obtain this CVL heat loss, and the guard heater control bias which obtains this guard heater power.

The determinations of the CVL guard heater control bias at the two (hot leg) fluid temperatures tre to be synthesized to produce a bias-versus-temperature relation to be used over the entire range of testing tempera-tures. (It is planned to develope and use a linear, and approximate, variation of bias with temperature.) The observations of CVL conditions

( attendant to these characterization steps w111 demonstrate model CVL performance and will provide opportunities to compare performance to predictions.

2.3 Conduct Initialize the primary in steady-state subcooled natural circulation at 2%

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core power (plus u ncompensated losses to ambient). Initialize the SG 2-2

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l secondaries at 1225 psia. Use high-elevation (minimum-wetting) AFW

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injection and constant SG 1evel control at 31.6 feet. Control the system l

guard heaters in automatic (for minimum zonal heat losses), with the exception of the CVL gu a rd heater. Leave the CVL guard heater de-energized.

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1. Q.q1mine CVL Heat Loss Without Guard Heating f Maintain steady loop and CVL conditions for at least one hour (the CVL transit time is roughly one-half hour). Base CVL steady state on the stabilization of the CVL orifice di f ferential pressure and the CVL inlet and outlet fluid temperatures. Record the CVL flowrate and bracketing fluid temperatures. Calculate and record the apparent CVL l heat loss to ambient without guard heating (qi, watts) by applying a CVL heat balance as follows:

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qi = rCVL (ibm /s) AhCVL (BTU /lbm) 3600/3.412 (ws/ BTU) where: 5 = CVL mass flowrate, lbm/s, and CVL Ah CVL = CVL fluid enthalpy change, BTU /lbm l

l Estimated Conditions:

The MIST CVL is expected to lose roughly 200 w without guard heating, l The corresponding CVL conditions are then approximately:

I m = -5x10

-3 lbm/s, Ap = -2 psi, and AT = -25 F, 2-3 mmum

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{ where the negative signs indicate reverse flow through the CVL, i.e. from the SG to the RVUH.

2. Determine the CVL Guard Heater Fower Raouired to Null the CVL Heat Lomm Discunnion ,

This step involves the determination of the total CVL guard heater

' input power required to render the CVL approximately adiabatic (Q2 '

( kw).. The CVL guard heater is first deliberately overpowered, to hasten the attainment of stable conditions by drawing RVUH fluid through the line. The CVL guard heater control bias is then set to zero, assuming that a bias near zero will balance the CVL heat losses.

Next, the CVL guard heater control bias is adjusted as required to minimize the apparent CVL heat losses. If the CVL heat losses are

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exactly nulled, then the CVL inlet and outlet fluid temperatures will equal the RVUH fluid tempera 5ure and the CVL fluid will flow upward (in response to the differential pressure across the vent line due to irrecoverable l'osses in the hot leg branch). The steady-state CVL flowrate with zero heat losses is only approximately 4x104 lbm/s, the corresponding pressure drop across the CVL orifice is 0.01 psi.

Evol ution Maintain the conditions used in determination #1 above. Energize the CVL guard heater and adjust its total input power to be roughly 10%

greater than that required for zero bias. Hold this setting for at least one-half hour, and until the pressure drop across the CVL has become positive (indicating that the CVL flow direction has changed to 2-4

I II upflow). Then reduce the CVL guard heater control bias to zero, and hold zero bias for at least one hour and until the CVL conditions have apparently stabilized.

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Evaluate the current CVL heat loss by comparing the CVL inlet and outlet fluid temperatures. If the fluid temperature difference across the CVL is non-zero and significant compared to the sensitivity of the temperature indications, then tune the CVL guard heater control bias to reduce this temperature difference. Hold each control bias setting for at least one hour. Perform not. more than three, of these adjust-I ment-wait evolutions. Select that adjustment which best-approximates zero heat loss to determine the total guard heater power for zero CVL heat loss (Q , kw).

2 I

3. A_d i u st the CVL Guard Heater Control Bias .t o Obtain the Desi red CVL Heat loss Determine the desired guard heater power (Q 3 , kw) using:

Q3 I9 3 ) " 02 (l~93 41 )

where q3 = Desired CVL heat loss, w; Q2 = Guard heater power (kw) required to offset CVL heat loss, from Determination #2 above; and qi = CVL heat loss (w) without guard heating, from Determination il abcve.

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This equation for Q3 assumes that the CVL heat losses vary inversely with the CVL guard heater input power. Although the accuracy of this 2-5 1

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( assumption is unknown, the resulting guard heater power is expected to be at least of the proper magnitude.

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Discussion The dest red CVL heat loss to ambient is roughly 10w at 600F. As l l

addressed' in Appendix A, a fairly broad range of MIST CVL heat los'ses l 1s tolerable. Therefore it is suggested that the desired CVL heat loss at 600F, q3, be increased beyond low such that it is roughly twice the p

apparent sensitivity of the CVL guard heating control. For example, if the minimum sensitivity of the CVL guard heater and control is such that the CVL heat loss can be controlled to within 10w, then set the desired CVL heat loss . (q3) to 20. watts. .

The desired guard heater input power then:

Q3 (q3 = 20w) = 02 (1-20/q1) 5 The power supplied to the CVL may be 5% of the total guard heater power. (The limit, with uniform guard heating and a uniform component, is zero.) If qi, the CVL heat loss without guard heating, was 200w, the guard heater input power for an adiabatic CVL (0 2) would then be 200/0.05 = 4 kw, and the desired guard heater power (Q )3 would be:

i 03 = 4 kw (1-20/200)

= 0.9x4 = 3.6 kw

[ The next step involves steady-state observations using the desired CVL The CVL guard heater is first deenergized

{ guard heater input power.

to hasten the transition from the preceding step to this one.

2-6

E si- Evolution Deenergize the CVL guard heater. When the di f fe rential pressure across the CVL orifice becomes negative (indicating that the direction d

'W of flow in the CVL has reversed to downflow), immediately reenergize

. the CVL guard heater. Manually adjust the CVL guard heater controller to obtain the desired total input power (Q 3). Maintain this configd-ration for at least two hours, and until the CVL conditions have apparently stabilized. Then record the CVL guard heater control bias I (corresponding to the desired input power) and the CVL conditions.

Conditions:

The steady-state CVL c6nditions vary with CVL heat loss, as described in Appendix A. For a CVL heat loss of 20w and a hot leg temp 9rature of -60CF, the following approximate conditions are expected:

m = -1x10 -3 lbm/s I CVL ApCVL ( rifice) = -0.1 psi CVL AT = -15F where the minus signs indicate downflow. (Note that the expected mass flowrate and orifice differential pressure are so small as to preclude an accurate determination of CVL heat loss di rectly by fluid heat bal ance) .

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4. Cooldown to the Next Settino Initiate a depressurization of the SG secondaries to obtain a 20F/h coolcown rate. Maintain the other system controls (CVL guard heater bias set for Q 3). Observe the indicatic,ns of CVL flow direction.

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( When reversal (to forward flow) is indicated, and after at least one l

hour of cooldown, institute the following actions:

o Activate HPI to maintain a mid-range pressurizer level during the cooldown.

o Increase the rate of SG secondary depressurization to obtain a 50F/h cooldown.

l b o De-energize the CVL guard heater.

l o ' Allow primary pressure to decrease.

( The' second temperature setting is 400F (see Table 2.1). Continue the cocidown to -350F (to hasten the RVUH and CVL cooldown). When the RVUH and CVL fluid and metal temperatures bracket the desired hot leg temperature (the target is 400F), reset the SG secondary pressure control point to 135 psia. Adjust the pressurizer heater control points to obtain 500 psia primary pressure. Suspend high-pressure injection.

5. Determinations At The Second Setting Allow the CVL conditions to stabilize and repeat the determination of CVL heat loss without guard heating but at reduced temperature (q1')f as in Ostermination #1 above. Energize the guard heaters and repeat the determination of guard heater input power to balance the CVL heat losses at reduced temperature (0 2') as in Determination #2 above.

i 2-8

Determine the desired CVL heat loss at reduced temperature (q3') by prorating the desired CVL heat loss at 600F (q3) according to the r reduction in total' heat loss, i.e.

93 ' " (9 1'/91) 9 3*

where primed quantities denote those at the s.econd, lower temperature settings. i 1

( Then determine the required guard heater input power in the usual fashion, 03 ' = 02 ' (1-93 '/9 1 ')*

De-encegize the CVL guard heater, then energize it, adjust its output

( to the desired value (Q3 '), and observe the CVL conditions as in Step

3 above.

6. Deoressurization Af ter the Final CVL Adiustinents After the final CVL guard heater adjustment (to obtain the desired CVL heat loss) has been made, pe: form the following steps to observe CVL performance with vipor flow:

i o De-energize the pressurizer heaters (such as by reducing the beater control pressure to the minimum).

o Manually open the PORV; maintain the PORY open until the RVUH has been voided (down to the elevation of the reactor vessel vent 2-9

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8 val.ves ) or until there are indications of steady vapor flow through the CVL, whichever occurs earlier, j l

o Terminate the CVL characterization tests.

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Discussion The major result of this characterization test is the bias required to obtain the desired CVL heat loss, at two temperatures. These biases l

will be used to define bias as a linear functior. of temperature. This l relation is to be used to control the CVL guard heater during the subsequent CVL tests.

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2-10

't c3' TABLE 7.1 CHARACTERIZATION CONDITIONS I

. W Both Points: Core Power = 2% (66 kw) + losses Setting Number 1 2 Approx. HL Temp. F 600 400 au Tmnosed Conditions S3 Secondary Pressure, psia 1225 , 135 Primary Pressure, psia 2200 500 I Derived Ccnditions (Anorox.)

Cold Leg Temperature, F 570 350 Hot Leg Temperature, F 600 400 Primary Saturation Temperature, F 650 467 Hot Leg Subcooling, F 50 67 I

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Figure 2-1 Heat loss Vs. Temoerature

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3.0 NATURAL CIRCUL ATION COOLDOWN (TEST 3701)

The purpose, description, and conduct of Test 3701, natural ci rculation

( cooldown (with continuous venting) are given in the following sections.

Whereas the test performance is specified in Section 3.3 (Conduct), the background of these specifications and expected loop behavior are discussed in Section 3.2 -(Description).

3.1 Purnose

{

The purpose of Test 3701 is to charactertze the CVL performance during

.a natural circulation cooldown. RVUH cooling with liquid flow through the CVL, as well as with vapor flow, is to be observed.

3.2 Descriotion A natural circulation cooldown is performed with the continuous vent line

( (CVL) installed, and guard heated to obtain the desired heat loss (determined in the characterization test, Section 2). The system cooldown rate is selected such that the following two modes of CVL operation will be obtained:

l. A detectable amount of RVUH cooling will occur by liquid flow through

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the CVL, before the RYUH saturates and voids.

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2. The RVUH will saturate later during the cooldown such that vapor flow through the CVL will be observed.

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The system is initialized using conditions similar to those of the usual

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MIST (natural circu'.ation) tests. These initialization conditions include: -

o 3.55. core power (plus uncompensated losses to ambient), where 1% of I

scaled full power = 33 kw and 3.55 simulates 1 min 40s after reactor trip.

l

( o 1010 psia steam generator secondary pressure.

This combination of core power and secondary pressure yield a suitably high initial HL and RVUH temperature, approximately 595F. These conditions and

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the resulting primary and secondary flowrates and fluid temperatures are listed in Table 3.1.

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( Certain pretest . conditions are rev i.?ed from those of the usual MIST conditions to minimize the imposed transient upon test initiation, thereby highlighting the cooldown and continuous vent line (CVL) ef fects. These revised conditions include:

( o Mid-height pressurizer level (5 feet within the pressurizer).

o 30-ft SG secondary level.

[ The mid-range initi al pressurizer leve1 ~ facilitates pressurizer level control during the cooldown, while the 30-ft initial secondary level eliminates the need to refill the steam generators to this level upon 3-2

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

[

test initiation *, An initial primary. pressure of 2200 psia is selected to obtain a substantial initial (core-exit-fluid) subcooling -- a subcooling of 100F will be used during the cooldown, as discussed below.

[ The reactor vessel vent valves (RVVYs) are to be controlled in automatic /

independent during initialization, to minimize their operation at test initiation (again to emphasize CVL effects). If the RVVVs continue to

( cycle during initialization, or if their positions vary from valve to val ve, then the manual-closed mode must be used to obtain pretest steady

[ .

state. (In this instance, RVVV control is to be change to automatic /

5, independent during test initiation.)

[

Test initiation consists primarily of beginning the SG secondary depres-(

surization ramp to reduce the SG secondary saturation temperature at

( 100F/h, thus cooling the primary at 100F/h. Also, high-pressure injection is to be used to maintain pressurizer level. The choice of the cooldown

[ rate and primary subcooling are discussed below.

Estimates of RVdH. cooling have been given in Appendix A (note that the

( predictions of Appendix A are approximate). The RVUH. cooling rate is predicted to lag that of the primary system, but to increase as the cool dow n progresses (and after the CVL flow direction has reversed to

[ *The 30-foot steam generator secondary level in MIST simulates the 10-foot secondary level in Davis Besse during a natural circulation cooldown.

Recall that the plant has a raised-loop configuration whereas MIST simulates the configuration of the lowered-loop plants.

3-3

Referring to Figure A.1 of Appendix A, the normalized RYUH

{ upflew).

cooling rate versus time is similar for various system cooldown rates; that is, the ratio of the RYUH cooldown rate to the system cooldown rate is roughly constant for system cooldown rates greater than approximately 25F/h. Therefore, there is no advantage to be gained by selecting any particular cooldown rate, in terms of the difference between the initial RVUH fluid temperature and that at saturation, provided that the CVL flow

{ reverses within a few minutes after the system cooldown is started (cf. Figure A.1). Therefore, a system cooldown rate of 100F/h was chosen to be fast enough that the CVL flow reversal (and subsequent RVUH cooling) would occur early in the transient. This rate was limited to 100F/h simply to provide an orderly test transient.

Figure 3.1 depicts the system fluid temperatures versus time for a 100F/h

( cooldown from time zero. Note the RVUH fluid temperature. Based on the approximate predictions described in Appendix A, the start of the upper head cooldown is expected to be del ayed roughly ten minutes after the start of the system cooldown (until the CVL flow has reversed and attained a substantial amount of upflow). Then the RVUH cooldown rate is expected

{ to increase gradually, in response to the increasing RVUH-minus-hot leg temperature difference. The predictions of Appendix A can be correlated to provide the transient RVUH cooldown rate (but it should be re-emphasized that the predictions are only approximate). This RYUH cooldown rate is:

r $I R (ST-1)/10 for 0.21 T 11 where: r = RVUH cooldown rate, F/h 3-4

_ _ _ _ _ _ ___m___ _ _

[ -

( R = System cooldown rate, F/h .

T = Time after start of system cooling, hours l

[

This correlation of RVUH couldown rate obtains the RVUH temperature-versus-

[ time shown in Figure 3.1.

[

The time of RVUH saturation should be delayed sufficiently to permit

( observation of RVUH cooling with liquid flow through the CVL. This delay of RVUH saturation can be obtained by increasing the primary fluid subcooling, but, on the other ' hand, the primary subcooling must be limited to observe the test facility limit on maximum primary-minus-secondary pressure difference. These considerations obtained a primary subcooling of

( 100F. The RVUH will saturate after roughly 1 1/2 hours of system cooling, at 550F, after an RVUH cooldown of 45F, The maximum primary-to-secondary

[ pressure difference will be 1440 psi with 100F subcooling, or if,00 psi if the primary subcooling is allowed to increase to 110F. This approach to

[

the maximum primary-to-secondary pressure difference will occur one-half hour after the start of the system cooldown.

When the RVUH fluid reaches saturation, voids are expected to be discharged out of the RVUH and into the CVL. Should voids collect in either the RVUH or the CVL, the attendant decrease in the CVL-branch (versus HL) fluid density vill augment the CVL flowrate and thereby suppress RVUH void

[

growth, both by increased convective removal of vapor and by enhanced RVUH cooling. Voids are likely to collect in the horizontal run of the CVL,

{

however, due to the down-sloping run of CVL piping leading to the SG inlet

[

3-5

( -

[

pl enum. This CVL void collection may lead to cyclic line behavior, i.e. a

{

period of collection followed by a period of CVL vapor condensation' by {

( interaction with the subcooled HL fluid. But iihese CVL events will probably be overshadowed by the periodic primary depressurizations through manual PORY actuation.

[ Conduct l 3.3 , l 3.3.1 Pre-Test Steadv State

{

Initialize the system in subcooled natural circulation with the continuous b vent line installed, as specified in Table 3.1. As noted in Table 3.1, use automatic / independent control of the RVVVs unless the valves cycle, or remain in differing positions (open and closed); in tnis instance, close the RVVVs manually.

{

( The system guard heaters are to be functioning in automatic control.

Whereas the bulk of the guard heaters serve to minimize the zonal heat losses to ambient, the CVL guard heater'is to be controlled to obtain the desired heat loss to ambient (determined in the characterization test,

[ Section 2).

[

Observe steady state for at least 30 minutes. In addition to the customary b criteria for the stability of system conditions, apply the following two criteria regarding the stability of the CVL conditions (modify both of

[ these criteria to account for the instrument and data acquisition system minimum sensitivities as they apply to the magnitude of the current CVL indications):

[

3-6

o CVL flowrate varying less than 10% (of the average CVL flowrate) over the 30-minute period.

o CVL inlet and outlet fluid temperatures each varying less'than 2F over the 30-minute period.

If cyclic variatiors of CVL conditions are observed, attempt to identify, and to remedy if deemed appropriate, the cause(s) of such cylic variations. After steady state has been achieved, activate the data

, acquisition and recording system, and obtain at least ten minutes of steady state data at acquisition periods of 30 seconds or less.

3.3.2 Initiation The test-initiation actions are specified in Table 3.2. Because ortly the initiation of the SG secondary depressurization ramp is key to the test i transient, the timing and order of the test-initiating actions is not cruci al . Note that throttled rather than full HPI flow is to be used to maintain a mid-range pressurizer level.

1 3.3.3 Control During Testing Control curing testing is outlined in Table 3.3. The folicwing three automatic control functions are to be continued throughout the test:

1. Depressurize the SG secondary to reduce the secondary saturation temperature at 100F/h. Continue this secondary depressurization down to the minimum SG secondary pressure.

1 3-7

[ ,

i

2. Reduce core power (simulating post-trip decay).

{

[ 3. Maintain constant SG 1evel control at 30 t 1 feet.

Manual WI throttling for pressurizer level is required throughout the test.

l

[ The control of the PORY and the pressurizer heaters varies during the test, as follows:

o Pre-test, initiation, and i niti c '. system cooldown until the core-exit

[ subcoolinrj attains 100F:

Control the PORY in automatic for over-pressure control.

{

Control the pressurizer heaters in automatic to maintain 2200 i b 25 psia primary pressure.

[ o After the core-exit subcooling first exceeds 100F:

When the core-exit subcooling reaches 110F, manually open the PORY to reduce t;te core-exit subcooling to 100F.

[

Manually de-energize the pressurizer (main) heaters. Energize the pressurizer main heaters only when the core-exit subcooling is less than 90F.

The core flood tank is to remain manually isolated, and the hot leg vents

{

are to remain closed, throughout the test. No controlled leaks or

[ 3-8

[ .

iu

I

.. j injections of noncondensible gas are to be used in this natural circulation !

(

f,- cool down.

I 1

e l 3.3.4 Termiration After the SG secondary pressures have been reduced to their minimum value, the primary is to be depressurized and then the test is to be terminated. !

Perform this primary system dep essurization one hour after the secondary pressures have approached their minimum values -- base this determination on a change of secondary saturation temperature of less than 10F in 30

- - minutes. When this criterion 'is satisfied, depressurize the primary to reduce the core-exit subcooling to 25F. Depressurize using manual PORY actuations (with .the pressurizer main heaters de-energized). Hold 25F core-exit subcooling for 30 minutes, then terminate the test by recording the time of test termination and then refilling the primary system expeditiously (the entire primary system should admit to being refilled).

Cease data recording when rofill has been completed. .

I The duration of the 100F/h cooldown is 3 to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . The depressurization at test termination will require approximately one (1) hour, post-termina-tion refill will r%uire less than 30 minutes. The total test duration is thus roughly five hours, another three hours (beyond the usual MIST stabilization time) may be required to achieve pre-test steady state.

/ 3.3.5 Meas urements Record the instruments identified as being critical for the standard MIST Phase 3 tests (refer to the MIST Test Specifications,7 BAW-1894, Appendix 3-9 i

r

F, instrument categories "A" - required and "C" - portion required). Also record each of the CVL instruments (differential pressures for flow and 1evel, fluid temperatures, metal temperature, and guard heater input c

power) .

{

[ Record these instruments at the frequencies specified for the standard MIST Phase 3 tests (cf. Appendix F, Section F.2 of the MIST Test Specifica-tions 7 ). In addition, record the critical instruments at 15-second c intervals, or more often, during the following three periods:

b .

l. From test initiation until the CVL flow reversal is observed.

{

2. From the time at which the subcooling of the RVUH fluid decreases to 10F, until 2 minutes beyond the second primary depressurization (manual PORY actuation) after the RVUH fluid = has apparently reached saturation.

3. During the primary depressurization upon test termination.

[

3.3.6 Accentance criteria

[ The test-acceptance criteria are as follows:

1. At least ten minutes of data is recorded at the specified pre-test conditions.

2. The test is i nit i ated, conducted, and terminated as specified; the automatic control functions perform as designed.

{ 3. The specified critical measurements are recorded at the prescribed acquisition frequencies.

[

3-10

[

TABLE 3.1 INITIAL CONDITIONS. TEST 3701

" Derived" conditions result from those specified and are approximate.

Table entries preceded by an asterisx (*) denote those conditions wnich

[ differ from the customary MIST natural circulat*on initial conditions.

Maximum

[ Quantity Snacification Deviation Derived t{g1;g Primary

[

The primary system is in subcooled natural circulation; boundary systems are inactive; the guard heaters are in automatic operation; the PORY is in l

[ the automatic overpressure control mode; the CFT is (manually) isol ated. l The CVL guard heater is operating in automatic with its bias adjusted to obtain the desired model CVL heat loss to ambient. The RVVVs are being

( . controlled in automatic / independent (See Note 3 below).

Core Power, %

of Scaled Power 3.50 0.05 ,

1,2 Pressure, psia *2200 25 Thot, F 595 Tcol d, F 550 Flow Rate, % of Scaled Full Flow' 3.5 2 PZR Level, ft (within PZR) *5 1 Subcooling, F *55

(

Secondaries i SGs are balanced with high-elevation AFW injection using the minimum wetting configuration; the AFW temperature is 100 20F.

Pressure, psia 1010 ,

10 Level, ft *30 1 Flow Rate, 5 of Scaled Full Secondary Flow 2.5 2 f

3-11

L

[

Table 3.1 (Continued)

{

[

~1. Increase core power as required 'to offset the uncompensated primary d system heat losses to ambient.

2. Conversion factors (rounded):

15 power = 33 kw = 31.3 BTU /s t 15 primary flow = 0.46 lba/s = 1660 lbm/h 1% secondary flow = 0.038 lbm/s = 138 lbm/h

' 3. If all the RVVVs remain either open or closed during taitialization, retain automatic / independent cor. trol of the RVVYs. If, however, the ,

RVVVs continue to cycle open and shut (or if the RYYYs re. main in '

differing positions), transfer RVVV control frora automatic /indepenient

[ to manually shut.

i

[

f 3-i2

[ -

TABL F 3.2 INITI ATION. TEST 3701 0 Transfer RVVV control from manually closed to automatic / independent, if manually-closed control was used during initialization.

O Actuate the corepower-reduction ramp (simulating decay from 1 min 40s r' after trip).

( .

O Activate the SG secondary depressurization ramp to obtain a 100F/h cooldown.

\

0 . Note and record the time of test initiation. l 0 Begin throttled HPI to maintain pressurizer level.

{

[

f .

[ .

f

[

[ -

[

(

3-13

il TABt F 3.3 CONTROL DURING TESTING. TEST 3701 11 Control Mode Cevnnonent Automatic M nual Destriotion 100F/h cooldown SG Secondary X

,( Pressure SG Secondary X Constant, Level 30 ft

,I HPI X Throttled injection to maintain 5t), ft I in pressurizer Pressurizer Heaters

- Untti 100F X Maintain 3 subcooling 2200t25 psia 5 obtained by system cooldown:

- After 100F X Deenergized.

subcooling Manually has first energize only I been when (core achieved: exit) ~

subcooling <

90F PORV X Overpressure I control Manually open I

X at 110F (core exit) subcool-

, ing, manually i close at 100F

( subcooling g Core Power X Decay ramp (3 CFT X Isola ted Hot Leg Vents X Closed lI 3-14

[

[ Estimated Primary Fluid Tc.1peratures Figure 3.1

'(Test 3701, Natural Circulation Cooldown)

' I b, .

l l -

,. i k t. ! i e.i i , ,

{ 3Mmt* N 22N EN l t ,i l

t l

l j

! I J ! ! i ! _! j ; ,

i ' i i i wi i i i i .a w,m ut i I

i i i !!N N t ; i ! /ool e //s# > '

(

I l L Ill l I

//

lI i i i i lI ! i IN i

! INN4N- ' , i/.sadig t

~

t,$. d,,a' ! II RVU 9 % I N M i -

(

i' l 4 'J "/ . , ,

! , i

!f!

i I 'M' i W

i ! , i ";'%N i ! i i N N! -

,,1 1 o} :N! i i r ii

7 i i i!s N iN N.i;;i i l i i iQ! i I ' i i i ! ' !

NN: N ml !

ti i l ll l 1 l 111 l t i I -l I i 1 4l ; '

hs 6% i i : 1 M ue ll,1 ! '% N '

U l i i Uf>7Ki ;

!\dF I i i ! (: V -

t.

i l t bN .yN .%

t i I lI i i r i iN i ;

i i Nii. ! Ahaks: ,i i i t' c-h i I ! \l !!\l i!(TM53

.! l . i I l i ,

mig ,

i i

i i ix l i

i N . i i ,' M )' 4 i , i i l'1 S i i i ,

I iN- i iXii . , . . !

{

l l l h ! l : i ! I 'N i i ! Nij.., ii i i i - '

.:.5 i ! I I i Ni ! -

lN, I ;- ! j '

!, i l ! i !

lN_ 'l

I i N: i i !

( !

! ! ld . I i l l ! ' ' ; j N _

r- i 'i.N i i I; '

t i i It I i i ! i ! ': i l cNI !

Mi i i I F i! i ' i i . ;

N' iN

( i ! ! ! ? I i : I i,,1 I : '

.N .

I i -

i ! t I !e IiI

i : i i ; -

! : N: i ! i i i _ h!m >

i i i ! i ii: . i i ! i i Ni

( l I i i' ~ i i 9 -

t i l I iii;ii ! 4 i ! i i .N' i Mii s I i

i I ! i i it i i i : i i i l i I N I I na it. ! I II iI I I I

! j l k f ; 0{Zl C i

! c{' ;If l /f l l;I ; ,' t.!,'/ ! l '-

i i ai e i ,4,iim,,i,u,,,

i i ; t l gj g j i - - - **iii,ii l l l 1 ll ll I I I /l 3-15

li 4.0 SRt OCA WITH NON00NDENSIBLES (TEST 37021 The purpose, description, and conduct of Test 3702, SBLOCA with noncondens-ibles and continuous venting, are given in the following sections. With the exception of continuous venting, this test replicates MIST Phase 3 Test 350312, "HL Venting With NCG and Ramoval of RV Head Gas," as described in Section 9.4 of the MIST Test Specifications.7 lI 4.. l Purnoso Test 3702 is intended to characterize the integral-system performance

{ during a post-SBLOCA' transient with noncondensibles and continuous venting.

1 4.2 Descrietion Actuation of the hot leg vents is expected to largely offset the noncon-densible gas (NCG) effects. Should the loop tend to stall and repressurize, the evolution of NCG at the hot leg U-bends (HLUBs) should increase the NCG concentration in the discharged steam and thus lead to subsequent loop flow and recoupling. If only NCG were discharged out the HPVs, the gas removal rate could far exceed the injection rate, thus the general transient may resemble that of venting without NCG.

l The ability of the continuous vent in conjunction with the HL vents to i

remove RV Head NCG will be explored. Late in the test transient, the leak is isolated and the PORY is used for primary system depressurization. The

! MIST HL vents (1 cm2 each) can discharge roughly 2 scf/ min of nitrogen at 200 psia ~ primary system pressure. This venting capacity increases approximately linearly with primary system pressure. The venting capacity 4-1 f

RI ;

with heliur. is more than twice that with nitrogen. Both venting estimates L ',

consider only,NCG being discharged. The vents must handle the combined gas

[

' sources including injection, evolution, and expansion. Of these sources, the expansion component is likely to predominate. Assume a gas-laden b voided' volumo of 2 ft3 (the volum's of the downcomer and reactor vessel down

/

k ts ths . r[o.'.zl e elevation). Fdr a continuous 100F/h coolderen, and a ccrresponding rate of depressurization to maintain a 75F subcooling margin, the gas generation rate due to expansion decreases from i scf/ min at 1500 psia, to 0.4.sef/ min at 200 psia. The minimum ratio of venting capacity to gas source rate thus , occurs with nitrogen at low system pressures, and exceeds five. But this ratio applies only for gradual depressurization.

~(Helium will be used if MIST is able to retain helium, cf. the MIST NCG Threshsid Test, Section d.3 of the MIST Test Specification7; otherwise

~

ritrogen will be injected.U

, The gas source due to expansion is likely to exceed the capacity of the vents during the abrupt primary system depressurization upon PORY actuation. The excess NCG. fs likely to collect in the Hl.UB region until it h -

is d(ssipated out the vents. It is unlikely to stop circulations however.

i The gendrally-occurring density difference between the HL fluid and SG prirary fluid allows voiding of the HLUB region, and of the HL piping, immediately downstream, while the upstream level remains above the HLUB spillover elevation and circulation continues. This HLUB-region volume alone is apparently sufficient to accommodate the gas generated by a PORY actuation, which reduces the core-exit subcooling margin by 10F, at all system pressures. In summary, c'rcult.cion and syr, tem cooldown are expected 4-2 a

to continue (in the second phase of the test, had circulation already been

{

reinttiated) or to begin upon the completion of loop refill. -

I 4.3 Conduct -

4.3.1 Steadv-State Pretest Conditions The primary is to be initialized in subcooled natural circulation with the primary bou nda ry systems (leak, HPI, and vents) inactive. The guard

[ heaters are in automatic operation. The RVVVs are manually closed. Core pcwor is 3.5% of scaled full power plus losses to ambient. Pressurizer level is 2.5 ft (within the pressurizer). The PORV is in automatic over-pressure control. The CFT is charged to 600 psia and recirculated. The continuous vent line is installed. The secondaries are balanced at 1010 psia and 5-foot liquid levels.

{

The primary CL and HL fluid temperatures will be approximately 550 and 595F, primary pressure is to be adjusted to obtain 22F subcooling (-1750 psia). These conditions and their tolerances are listed in Table 4.1.

4.3.2 Initiation .

( The Nominal Test is initiated in two steps. The first step is begun after at least ten minutes of steady-state data has been recorded at the specified initial conditions. The five actions to be taken in this step are:

l. Open the 10-cm2 B1-CLD (cold leg discharge) leak,

{

b 4-3 l

b

f

( 2. Enter the test-initiation time into the log,

3. Open both hot leg high-point vents (simultaneously),

4. Begin injecting NCG at the core inlet; and S. Verify that the PZR heaters trip on low PZR 1evel. (The leak contirol

{

valve limit switch activation will provide a test-initiation timing

[. mark in the data base.)

NCG Infection Rate Use a continuous NCG injection at the core inlet. Determine this injection rate by dividing the amount determined in the MIST NCG Threshold Test by

( the time interval from the results of the MIST Nominal Test (3100.00). If the volume of NCG exceeded the capacity of the NCG collection system, then use the maximum collection volume (-60 scf) to set the injection rate in this test. The time interval is from the initiation of the Nominal Test until BCM could no longer have occurred, i.e., when the primary levels in both steam generators finally exceeded the elevation of the upper tube-

{

.sh eets. The resulting injection rate for this test may be similar to that

[ used in the NCG Threshold Test, on the order of 20 sef/h. Adjust the gas addition system for the appropriate rate, and ' attempt to maintain a constant setting throughout the test. ,

Initiation Sten 7

( ' Test initiation Step 2 is to coincide with pressurizer draining and is to 4-4 M

( be completed by the time the HLUB fluid first saturates. The five actions of Step 2, in order of performance, include:

1. Adjust the SG secondary level control setpoint to 31.6 feet,*

2. Mtivate full ifI,

( 3. Initiate the core power decay ramp,

4. Transfer RVVV control to automatic / independent o'peration with open/close setpoints of 0.125 and 0.04 psi, and

5. Begin ATOG SG secondary pressure control.

[

These steps are listed in Table 4.2 I

4.3.3 control During Testing Most of the bounda ry system simulations are automated, cf. Table 4.3.

Manual control may be required in the following three circumstances: (1)

( Manually open the PORY, should the PORY actuate (automatically) on over-pressure; (2) isolate the CFT if permitted by subcooling; and (3) throttle

{ HPI to maintain a 3.4 t 0.5 ft PZR level provided that the PORY is closed and at least 50F SCM is maintained. Manual HPI throttling may also be

The 31.6-ft secondary level of the base test without continuous venting is

{ retained for inter-test comparison.

4-5 .

required with excessive subcooling should the primary pressure decrease below 600 psia while siediating full HFI cpacity. j Continue NCG injection until tes.t termination or until the threshold volume has been injected. Maintain the hot log vents open.

Phase 2 ,

j The ability to remove NCG from the RV Head using the CVL and HL vents during a natural circulation cooldown is to be examined late in the test.

Begin this phase of testing after the hot legs have been refilled and natural circulation has been observed for approximately ten (10) minutes.

To ensure that this second phase of the test is adequately explored, begin

( Phase 2 based on the following two critertai should either be satisfied prior to loop refill: (1) less than two hours of testing remain, or (2) primary system pressure decreases below 600 psia.

E Begin the second phase of the test by isolating the leak. Maintain the

{ status of the remaining system:. This includes HPI (full head-flow with automatic th ro ttl i ng .f o r 75F subcool ing or manual th rottl i ng for

[ pressurizer level), venting (both hot leg vents open), and NCG injection as previously described. The exception is PORY control. When the core exit fluid subcooling exceeds 70F, manually actuate the PORY to reduce the subcooling margin from 70 to 60F, then close the PORV. Continue this method of incremental primary system depressurization by manual PORY actuation for the duration of the test.

4-6 mes*

s

[ -

( 4.3.4 Termination The test may be terminated after the loop has been refilled, at least 50F core-exit subcool ing has been maintained for at least two hours, and the primary has been depressurized below 400 psie. " Loop" refill refers to the HL and CL piping and the RV upper head; the pressurizer may remain voided. Should refill not occur, the test should be terminated eleven hours after test initiation, in order to complete the test within the

( . maximum duration of twelve hours. ' Testing may also be terminated because of sustained low primary pressure. Termination may be delayed at the discretion of the Test Engineer. Upon' test termination, the termination time is to be entered in the log, but data taking is to be continued uninterrupted until the loop is refilled.

[

4.3.5 Mansurements Record the standard MIST critical instruments at the usual frequencies, as specified in Appendix F of the MIST Test Specifications.7 In addition to the usual critical measurements, obtain NCG closure within the limits of the gas injection and collection systems and their measurements. Obtain the gas disenarge amounts during post-termination refill of the loop.

( Estimate the amount of NCG remaining in the system. Also record the CVL -

indications (dif ferential pressures for flow rate and for level, fl u i'd temperatures, metal temperature, and guard heater input power).

4.3.6 Accentance Criteria The test acceptance criteria are as follows:

4-7 17 t

[ .

[

1. Steady-state data is recorded for at least ten minutes at the specified initial conditions.

2. The test is initiated as specified.

3. The b'ou nda ry system simulations function as specified, within the

[ limits of the measurement and control systems.

4. The test is terminated as specified.

5. YalId critical measurements are recorded at frequencies equal to or ,

exceeding those specified.

[

[ 4-8

[

( TABLE 4.1 INITIAL CONDITIONS. TEST 3707

\

" Derived" conditions result from those specified and are approximate.

Maximum Quantity Snaci fication Deviation De rived Ng.tg Primarv The primary system is in subcooled natural circulation; boundary systems

[. are inactive; the guard heaters are in automatic operation; the RVV.Vs are manually closed; the PORY is in the automatic overpressure control mode; the CFT is charged to 600 psia and has been recirculated (the MIST CFT is kept isolated until the primary. depressurines below 700 psta).

Core Power, %

of Scaled Power 3.50 0.05 1,3 ,

Pressure, psia . 1750 2

( Thot, F 595 Teoid,F 550 Flow Rate, % of Scaled Full Flow 3.5 3

( PZR Level, ft (within PZR) 2.5 0.2 Subcooling, F 22 2 2

{

Secondaries SGs are balanced with high-elevation AFW injection using the minimum wetting configuration; the AFW temperature is 100 t.20F.

[ Pressure, psia 1010 10 Level, ft 5 1 Flow Rate, % of Scaled Full Secondary Flow 2.5

{ 3

[

4-9

[

Table 4.1 (Continued)

{

( ,

1. Increase core power to offset the uncompensated system heat losses to ambient.

[ 2. Adjust primary pressure as required to obtain 22F initial primary subcooling. For example, if the steady HL temperature is 585F, then the initi'al T is to be 607F (versus 617F at 1750 psia). Saturation

[ pressure at 66N is 1625 psia, which establishes the revised initial primary pressure.

( 3. Conversion factors (rounded):

1% power = 33 kw = 31.3 GTU/s 1% primary flow = 0.46 lbr/s = 1660 lbm/h 15 secondary flow = 0.038 lbm/s = 138 lbm/h

[ .

[

4-10

1 TABLE 4.2 INITI ATION. TEST 3702 The initiation actions are to be performed in the order listed. The actions are described in detail in the accompanying text.

STEP 1: Perform Step 1 after at least ten minutes of steady-state data r has been recorded at the specified initial conditions.

l

l. Open tha 10-cm2 (scaled) B1-CLD (cold leg discharge) leak;

2. Enter the. test initiation time in the log;

3. Open both hot leg high-point vents (simultaneously);

i 4. Inject NCG at the core inlet. Use a continuous injection at the rate described in the text; and

5. Verify that tne pressurizer heaters trip on low pressurizer i

l evel .

'g STEP 2: Begin Step 2 as the pressurizer level depletes as a result of the I

g leak actuation performed in Step 1. Complete before the loop fluid saturates.

1. Adjust the SG secondary level control point from 5 to 31.6 feet; use the band control mode during the refill of the SG secondary;

2. Activate full high-pressure injection;

3. Initiate the core power decay ramp;

4. Transfer RVVV control from Manual-Closed to

, Automatic-Independent; and IE

E 5. Transfer steam generator secondary pressure control from Constant to ATOG.

il

!I il ll 4-11

[ .

TARLF 4.3 CONTROL DLIRING TESTING. TEST 3702

{

i

[ Summary of control functions during testing. Refer to the text for )

details.

Control Mode

( control Function Automatic tiangal tig.ta SG Secondary Level X

, SG Secondary Pressure X

I Head-Flow X Throttling Based on i Subcooling X 1 l

( Throttling Based on Pressurizer Level X l Primary Depressurization

{ , (Manual PORY Opening) X CFT Isolation 2 Low Level X

( Subcooling Regained X Venting (HPV) X 3 Core Power Decay ,

X Controlled Leak X 4 NOTE: 1. Manual HPI control may be necessary below 600 psia loop

[ pressure when full PI is being simulated and the core-exit fluid subcooling increases beyond 75F.

( 2. If the CFT is to be in service (i.e., not yet. isolated by the level or subcooling criteria), then the MIST CFT isola-tion valve is to be allowed to open automatically as the primary depressurizes below 650 psia.

{

3. The HL HPVs are to be kept open.

4. The controlled leak is to be isolated during the test, as described in the text.

4-12

l 5.0 HPI-PORV COOLING. TEST 3703 The purpose, description, and conduct of Test 3703 are given in the following sections. The test transient is patterned after a RELAP prediction of a LOFW transient which is described in Appendix C. The MIST boundary system characteristics required are addressed in Appendix D.

5.1 Purnose Test 3703, HPI-PORV cooling, institctes several of the operator actions and system characteristics relevant to Davis Besse. The' purpose of this test is to characterize long-duration feed and bleed cooling with a complete I loss of feed and, in particular, to document the integral-system interac-tions which occur as the declining hot leg level uncovers the surge line-to-hot leg connection.

I 5.2 Descriotion 5.2.1 Predicted Events The plant events predicted by RELAP are listed in Table 5.1. A more complete description of the predicted transient is given in Appendix C.

Note that the reactor is tripped approximately 15 seconds after the LOFW, but the reactor coolant pumps are kept operating uatil the subcooling margin decreases to 20F at 11.7 minutes (after the LOFW). It should also be noted that the primary system first depressurizes after the PORY is manually kept open, but subsequently repressurires (with the PORY still open). This repressurization occurs after the pumps are tripped, the rate of introduction of subcooled fluid into the core diminishes, and hence the core void generation rate increases markedly. (This repressurization lifts 5-1

'I

l the primary safeties, hence their simulation in MIST is needed; they are described in Appendix D.)

5.2.2 MIST Initf al conditions MIST is initialized, and the test is initiated, to simulate as closely as possible the conditions of the following loss-of-feedwater transient (described in Appendix C):

o 102% initial power, o PORY characteristics (cf. Appendix D) and o Operator actions ton minutes after T exceeds 600F.

I H0T Two MIST characteristics tear on this simulation, the maximum core power and the PORV actuation setpoint. The maximum MIST core power is 10% of scaled full power. This sets the earliest time in the transient which can oc simulated in MIST. Because the reactor is tripped well before the pumps are deenergized (on loss of subcooling margin), the MIST core power I

onstraint has little impact on the simulation.

The MIST ORY setpoints are as high in pressure as possible without lifting the test loop code safety. The MIST PORY actuation and reset pressures, 1

2350 and 2300 psia, are 115 psi less than those of Davis Besse. Because the transient of interest is governed by system fluid heatup and pressuri-zation versus PORY actuation, the MIST transient must be modified to accommodate the lower PORY actuation pressures. The lower PORY setpoints of MIST are accommodated by lowering the initial temperatures and primary pressure in the test transient, by lowering the hot leg fluid temperature l

5-2 I l

[ -

which triggers operator actions (from 600F in Davis Besse, to 590F in

{

MIST), and by shifting the . injection characteristics by 100 psi (cf.

Appendix D).

[ The MIST steady state initial conditions are compared to those predicted to occur early in the plant transient, in Table 5.2. The time of the listed

{

plant conditit,ns, 15s af_te r reactor trip, was selected based on the

[ .

available code output edits and the similitude between the predicted plant core power (8.8%) ai.: too maximum MIST core power (9.6% of scaled full power plus 0.45 to off set the uncompensated losses to ambient). It should l

be emphasized that the predicted plant conditions reflect an ongoing transient, whereas the MIST conditions are at steady state.

Even if MIST 1

{ was initialized to replicate each of the more-significant plant conditions at some particular time in the transient, the MIST conditions during the test transient would immediately diverge from those of the plant transient.

This disparity would be driven by the differences between the transient

[ plant heat transfer and transient energy storage rates, versus the rates in MIST at steady state. (It should be noted that the MIST transient timing

{

is al'so generally skewed from that of a plant, primarily due to the excess

( fluid volume in MIST compared to that of a power- and volume-scaled model.)

MIST is initialized therefore to preserve those conditions which govern the ensuing primary-system heatup and repressurization. These governing conditions include: primary system power, pressure, flow, and average fluid temperature.

[

~

[

5-3

[

Core power is set to the MIST maximum, 9.6% of scaled full power (plus 0.4%

to offset uncompensated losses to ambient). This simulates 10s of

[ post-trip decay; the reactor trip occurs 15s after the LOFW, in the plant prediction; therefore the MIST core power decay ramp is to be activated 25s after the LOFW is imposed. The MIST simulation of the predicted plant transient thus begins roughly one-half minute after the LOFW. i l

I The MIST primary system pressure is set at 2250 psia. This pressure is

{

based on the plant pressure at 15s after roactor trip, 2350 psia, less 100 h psi to accommodate the lowered PORY setpoints in MIST. The initial MIST primary system average fluid temperature, 580F, is similarly based on the

[ plant temperature, 590F, .less 10F to compensate for the lowered PORY setpoints. This primary average fluid temperature is obtained by adjusting the SG secondary pressure. The MIST primary flowrate is set to the MIST

[ four-pumps design point; this obtains 110% of scaled full flow in MIST, which is similar to the corresponding plant flowrate. ,

5.3 Conduct Pre-Test Steadv State ,

Stabilize MIST in forced flow at 10% of scaled full power (including

{

0.4% to of fset uncompensated losses to ambient). Adjust the steam

( generator secondary pressures to obtain cold leg temperatures of 577F. Use 5-ft SG secondary and pressurizer levels. These initial conditivns are

. summarized in Table 5.3.

[

[ 5-4

L

[

{ initiation Record steady-state data at the specified initial conditions for at le'ast ten minutes, then initiate the test transient by terminating AFW. Mark the time of simulated reactor trip (on which to base the core power decay ramp)

E Isolate and inert the SG secondaries at 15s after the termination of AFW.

using the technique of the MIST (Phase 3) HPI-PORY Cooling tests (Group 33,

{ Section 7 of the MIST Test Specification 7). Manually doenergize the l

( pressurizer heaters. The pressurizer spray is not to be used during this ,

test.

E90F Hot Lag Fluid Tamnerature Mark the time at which the (hotter) hot leg fluid temperature reaches 590F. Ten minutes after this time, institute the following actions

{

(simulating those of the plant operator): Manually open the PORV and hot leg vents, and activate makeup /HPI. Inject makeup through only the loop Al HPI nozzle..

20F SCM

{

When the core-exit subcooling margin decreases to 20F, trip all four RCPs

[ ,

and perform a simulated four-pump coastdown.

safetv valve control After the PORY has been opened manually, and when the primary pressure is less than 2300 psia, transfer control of the simulated safeties from

{ manual-closed to automatic aftuation on overpressure. Use the same setpoints as those of the MIST PORY (2350 psia to open and 2300 psia 5-5

[

i ii

reseat). These test-initiating actions are listed in Table 5.4. Control

^

during testing, Table 5.5, is generally an extension of these initiating actions.

WI/Mlj When primary pressure first decreases to approximately 1700 psia, transfer 1

from injection through the Al HPI nozzle to injection through all four HPI l noz zl es. Select this transfer pressure such that the AI-HPI flowmeter

{

remains within its calibrated range. Retain four-nozzle injection for the h duration of the test.

h ination Continue testing for at least three hours, but for not more than eight' hours. After three hours of testing, the test may be tenninated at the discretion of the Test Engineer when either of the following two criteria is met:

1. The core-region collapsed liquid level is more than three feet above its minimum value during the transient, or

2. Primary system pressure is less than 1500 psia.

{

[ Measura==nts and Acenntance criteria Record the category "A" (always critical) and "C" (portien critical) instruments identified in Appendix F of the MIST Test Specifications 7.

Record at the minimu.n intervals also specif fed in Appendix F of the MIST Test Specifications. In addition, record data at intervals of not more 5-6 C -

E than 15 seconds between scans during the following four phases of the test transient:

I

1. From test initiation until the PORY begins to actuate (from time O to approximately 2 minutes).

[ 2. From the time at which the PORY is kept open manually untti the primary system pressure stabilizes (from approximately 11 to 15 minutes). l

{

[ 3. From the time the RCPs are tripped until the simulated safeties actuate l (from approximately 12 to 25 min).

4. From the time at which the A-HL level approaches the elevation of the surgeline connection, untti the primary system begins to depressurize gradually (from approximately 35 to 45 min.).

The test acceptance criteria are as follows:

[ 1. At least ten minutes of data is recorded at the specified initial conditions.

( 2. The test is initiated, controlled, and terminated as s peci fied.

The simulated boundary systems perform as designed.

3. The critical measurements are recorded at the specified intervals.

[- 5-7 p

l .

1 t

TABLc 5.1 Predicted Events I

.t Time After LOFW Event 0 Loss of feedwater 15 to 16s Reactor and turbine tripped, PORY actuated u 1.5 min PORY began repeated actuations 1.6 min Hot leg fluid temperature 2. 600 F 8.3 min Pressurizer filled 11.6 min Operator actions (10 min after TH0T 2.600F): -

1 Opened PORY and vents, activated full makeup 11.7 min Core-region voiding began, tripped RCPs on SCM i 20F 13.3 min HLs voided briefly t 14.2 min Primary pressure stabilized at 2260 psia .

15.3 min Primary repressurizing 20 min HL levels began to decrease from nearly full 25.4 min Primary safeties began actuating periodically, pressurizer level began to decrease from full 35 min HL levels began to diverge, A-HL level near surgeline I * 'v*ti "

'E g 42 min B-HL drained 47 min A-HL drained, primary pressure began to declins, primary safeties ceased to actuate 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months Core-region collapsed liquid level achieved a minimum j value of approximately 12 feet

'I '

13 .

( 5-8 E

\\ .

m _ _ _ _

TABLE 5.2 PLANT AND MIST CONDITIONS. TEST 3703 e

The plant conditions are varying quite rapidly with time, the MIST

.. conditions are at steady state. The governing conditions are circled, see the text for details.

Predicted Plant Conditions at MIST 130.35s, Approximately Initial 15s After Rea:-tor Trio Conditions Core Power (%, based 8.8 on 2700 mw) i Core Fluid Temperatures, *

, F Inlet 586 577 Outlet 95 8 Average 590 580 Primary Pressure, psia 5 25 Pressurizer Level, ft* ~21 5 Primary Loop Flowrate

(%, based on 37500 lbm/s) 109 110 ll

Pressurizer level is in feet within the pressurizer, both the plant and MIST pressurizers are roughly half full.

,I

590F: l (1) Mark the time when THOT exceeds 590F (2) 10 minutes after THOT > 590F:

o Manually open the PORY o Open the HL vents o Initiate MU/HPI to Al-nozzle

3. When the core-exit subcooling margin decreases to 20F, initiate a four-pump coastdown.
,I 4. When primary pressure decreases to less than 2300 psia with the PORY manually oper., transfer control .of the primary safety to automatic.
'I
!I lE 13 5-11 f
TARIF E.5 CONTROL DURING TESTING. E 3703 I
J 0MPONEMT CONTROL MODE Associated Au+a=2 tic Manual Initiation Stan Primary System Core Power Decay X 1 Pressurizer
- Heaters X (Off) 1
- PORY X (0 pen) 2
- Safety X 4
- Spray X (Inactive)
Vents X (0 pen) 2 RCPs X (Off) 3 HPI/MU X 2 ,
(Use scaled head / i flow characteristics I given in Appendix D, and modified as required to observe the MIST limits on maximum HPI flowrate capacity and , ,
metering capability)
Secondary Svstam SGs inerted and isolated.
5-12 a
il
6.0 REFERENCES
3
1. B&W Doc. Nos. 86-1153988-00 and 32-1153987-00, "l/2" HIST Continuous Vent Line," March 7, 1985.
2. B&W Doc. Nos. 86-1153983-00 and 32-1153982-00, " MIST Continuous Vent Line," March 5,1985.
3. B&W Doc. Nos. 86-1152752-01 (June 26,1984) and 86-1152752-00 (June 25, 1,984), " Design Inputs For MIST RV Head Vent To Hot Leg."
/
'N 4. B&W Doc. Nos. 32-1149099-01 (March 15,1984) and 32-1149099-00 (February 15, 1984), "DB-1 RV Head Vent Heat Loss (Task 1)."
5. B&W Doc. No. 32-1149185-00, "DB-1 RV Head Vent Heat Loss (Task 2),"
February 27, 1984.
6. B&W Doc. No. 32-1150145-00, "DB-1 RV Head Vent Line Transients Analysis," February 27, 1984.
7. " MIST Test Specifications," BAW-1894, October 1985.
l
'I l
3 l 3 l 3
.g e.1 1 .
l
)
k APPENDIX A
{
CONTINUQUS VENT LINE PERFOMANCE 1.0 2NTR000CTION 2.0 CHARACTERISTICS 3.0 ETH00 0F AhALYSIS ,
4.0 PLANT CVL PERFORMANCE 5.0 MIST CVL PERFOMANCE 6.0 SLA44ARY 5
2
[
[
t l
l
1.0 INTRODUCTION
MIST is to simulate the plant continuous vent line (CVL). The plant and
. MIST reactor vessel and steam generaor elevations dictate the vertical runs of thef r CVLs; the lowered-loop configuration of MIST obtains a line elevation difference which is rough one-half that of the raised-loop plant. 1 4j 1 Considsrations of fluid stratification and two-phase performanco in MIST -
have been used to select the inodel itno sizo, such that the MIST CVL fluid and metal volumes are much greater than the power- or volume-scaled plant values. The purpose of this appendix is to estimate and compare the performance of the plant and MIST CVLs, to assess the impact of the MIST
.h 's CVL characteristics, and to evaluate the optimum range of model CVL hest Jg losses to ambient.
g The plant and MIST CVL characteristics are compared in Section 2. The CVL t.nalysis technique is cutlined in Section 3; the multiple approximations and assumptions of this analysis technique are identified. The plant CVL performance is descaibed, and compared to previous predictions of plant CVL performance in Section 4. (Extracts from these previous predictions are compiled in Appendix B.) The performanc.s of the MIST CVL is addressed in the Section 5.
I
!I 11 f
A-1 6
!I
11 1 2.0 Characteristics The plant, scaled plant, and MIST CVL characteristics are compared in Table A.1. The MIST CVL vertical longth is roughly one-half that of the (scaled)
. plant, because MIST models the lowered-loop configuration whereas the CVL
.f being simulated is on a raised-loop pl ant. The MIST CVL is sized to preserve two-phase flow and stratification behevior, thus the MIST CVL simulation is much more massive than the (power-scaled) plant continuous vent line. The product of fluid and metal mass times specific heats for MIST is roughly 14 times tqat of the scaled plant, whereas, for the RVUH, this product is roughly the same for MIST and the scaled plant.
The MIST and scaled plant hydraulic resistances are nearly identical over the loop flow path between the HL nozzle and the SG inlet plenum, but the MIST resistance over the CVL is roughly twice that of the corresponding scaled path. The plant CVL heat loss to ambient (at 600F) corresponde tc, roughly Sw at MIST scale; the appropriate MIST CVL heat loss will be 4ddressed herein. .
I II II
,-2 3
4
!I
3.0 EQLilIIDR_IEQlFlGE e
The performance of the (scaled) plant and MIST CVLs is predicted for 4 comparison. The basis of this prediction is the determination of the CVL flowrate required to balance the RVUH-to-SG inlet differential pressure
.fg over the two parallel flow paths, namely the hot leg and the CVL. This (g
calculation may be done manually, but the combined effects of the feedback due to CVL heat loss and a loop transient (such as a controlled cooldown) suggest a rudirrentary computer program.
The program logic is outlined in Table 2. Numerous approximations were introduced to simplify the problem. The program listing (for a Commodore
64) is given in Table A.3. The more-significent approximations and assumptions are as follows:
!I
, o Loop flowrate (F, % of full flow) varies with core powcr (Q, % of full powor) as F = 3' ( 0/ 2 )**l/3. Note that this approximation is more l3 appropriate for the lowered-loop configuration than for the raised'-loop ig
configuration.
II o The core temperature rise (DT, F) is DT = 50 (0/F).
I
( o The fluid density (RHO,1bm/ft )3taries with temperature (T, F) as RHO = 14.723 (705,5-T)*M).225 (This is a manual fit to the RH0(T) data from the ASME-67 steam tables, over the range 1001 T (F) 1600).
^-3
[l 1 l
L 9 t
. o 1The primary fluid is single-phase liquid.
L
(! o Core power varies with transient time (t, min) as Q = 2 - VM F .
4 (The transient duration was generally limited to 60 minutes).
- 1 Y
o The cold leg fluid temperature (TC,F) equals tne SG secondary fluid -
l temperature. Thus, for an imposed cooldown rate (CD, F/h) from 550F, the cold leg fluid temperature is TC=550-CD(t/605.
o The' CVL and RYUH fluid conditions are each assigned single values, thus ignoring 'both fluid migration times (other than through the inherent temperature-gradient dilution!, and the local variations of fluid conditions.
f'
! o Time dependence was addre:: sad by applying 'mean values (of CVL flowrate and of CVL and RVUH fluid temperature and density) over the precedirig time increent. These mean values were assigned by averaging the results at the previous and current times, o The CVL heat loss (QW, watts) was assumed to decrease linearly with CVL temperature (TCVL, F) from the input value (QIN) at 600F, to zero at
'100F, f.o. (N = OIN (TCVL-100)/500 o The CVL and RVUH fluid specific heats were taken to be 1 (BTU /lbm F).
. A-4
re Th3 CVL heat loss due to fluid transport was obt:ined from the product L
of the CVL flowrate and (TIN-TCVL), where the incoming fluid temperature (TIN,F) was equated to the upper head fluid temperature if the CVL flow direction was upward, or to the hot leg fluid temperature if the CVL flow direction was downward. -
1 The RVUH (fluid and metal) was assumed to change stored energy only due l to CVL flow (RYUH losses to ambient were ignored).
[
o The RVUH energy change due to fluid transport was equated to the product cf the CVL flowrate and the difference between the head temperature and tho inlet fluid temperature. For upward CVL flow, the inlet temperature ,
i:as TNT, and for downflow it was the temperature of the CVL.
Tho most restrictive . assumption was that regarding lumped fluid and metal.
No spLtial distribution was calculated, nor was the metti conduction time dolay considered. The results must be considered qualitative rather than quantitative, i.e. they are useful o'nl y for comparing trends. They are thus useful for comparing the predicted MIST CVL performance to that of the (scalcd) plant.
[
[
A-5
[
as *
( 1mposed cooldown rate to -9 min with 20F/h. The corresponding (RYUH-minus-HL) tunperature differences at reversal range from 2.5 to 4.4F.
' The plant prediction with an imposed CL cooldown rate of 10F/h is markedly different from the others, as in apparent in Figure A.1. The CVL flow reversal is del ayed for 54 minutes, at which tiine the RVUH-minus-HL
{'
temperature difference is roughly 20F. But the predicted RVUH cooldown
[ rate then ir. creases rapidl y, exceeding the normalized rate of the other cases within a few minutes.
The plant CVL flowrates have been predicted independently,* for revising the RCS functional specification. Figure A-2 compares this independent
( prediction (with the CVL flowrate reduced by 817, the MIST predominant scale factor) with the predictions herein, both with an imposed cooldown rate of 50F/h. The two. predictions are similar, both for steady state and through the transient. But this similitude is not maintained for smaller rates of imposed cooldown. Whereas the CVL flow reversal was predicted herein to occur at roughly 9 minutes with an imposed cooldoen rate of 10F/h (Table A.3), the earlier calculation for a higher imposed cooldown rate, 25F/h, precticted that the CVL flow reversal would be delayed for roughly two hours. These disparate predictions are shown in Figure A.3. The differences between these two predictions illustrate that the CVL conditions become more unstable, and the predictions become more sensitive-( *B&W Doc. ID. 32-1150145-00 of 2/27/84. Extracts from this source and others are compiled in Appendix B. s A-7
[
to assumptions and techniques, as the imposed cooldown rate is reduced.
Note that the predictions herein did obtain a delayed flow reversal with an imposed cooldown rato of 10F/h, as shown in Figure A.l.
( The plant vent line flowrates versus RYUH-minus-HL temperature difference, with various insul ation thicknesses, have been calcul ated in B&W .
Doc. No. 32-1149099-00 of February 15,1984 (also extracted in Appendix B).
The CVL flowrate with a nearly zero RYUH-to-HL temperature di fference was predicted to range from -8.6 gpm with 3-inch tnick insulation, to -15.3 gpm with no insulation. These flowrates correspond to -1.2 to -2.1x10-3 lbm/s at MIST scale, and thus bracket the steady-state ficwrate (-1.3x10-3 lbm/s) predicted herein. The referenced calculation permits inferences regarding increased CVL heat loss (i.e., less insul ation) . As the ' CVL
, losses to ambient are increased:
[
o The steady-state CVL flowrate becomes more negative. i o The RVUH-minus-HL temperature dif ference at CVL ficw reversal becomes larger (3F with 3 inches of insulation, almost 6F with no insulation).
These plant predictions illustrate the same trends as predicted herein for the MIST CVL (varying losses to ambient by adjusting the guard heater
{
controls); these MIST predictions are described in the next section.
[
[
A-8
[
I - E- _ _ _ . _ _ _ _ _ _ . _ _ . __
5.0 MIST CVL PERFORMANCE Five cases pertaining to MIST were predicted, as indicated in Table A.4.
l Case 5 used the elevations, and metal and fluid stored energy characteris-tics, of MIST, rather than those of the scaled plant. The CVL heat loss to
( ambient was doubled in Case 6, from ~5w in the, scaled plant to 10w. The hydraulic resistance of the CVL of Case 6 was roughly doubled, in Case 7.
. The CVL heat loss was again doubled in Case 8, from 10 to 20w. Fiaally, in Case 9, the calculational time increment was increased from 1 to 10 minutes. The purpose of these predictions was to estimate the performance of the MIST CVL versus tnat of the plant- and to assess the impact of the individual MIST CVL variants, particularly heat loss.
Each of the MIST CVL predictions used an imposed (CL) cooldown rate of ,
1 20F/h, which is low enough to obtain a detectable delay until CVL flow reversal, but high enough to avoid the unstable (and long-running) calculations with lesser cooldown rates. The MIST predictions are compared
( to the corresponding plant prediction in Figures A.4 and A.S.
Referring to Figure A.4, each of the MIST predictions yielded a less-nega-tive CVL flowrate at steady-state than did the plant prediction. This ap pa rentl y reflects the reduced CVL vertical length and hence natural circulation driving head in MIST. The MISi transient CVL flowrates (after
{
flow reve rsal ) are also less than those of the scaled pl ant. These h transient differences reflect not only the decreased MIST CVL vertical distance but also the much more massive MIST CVL (compared to that of the power-scaled plant).
A-9
[
[ .
The MIST RVUH cooldown ratn is roughly one-half ::f that of the plant, after
.one-hal f hour of imposed cool down (Figure A.5). This reduced RYUH cooldown rate reflects the reduced CVL flowrate in MIST. (As the imposed
{
cooldown proceeds, the RVUH-to-HL temperature difference will increass in
( inverse propation to the initial RVUH cooldown rate, therefore the RVUH cooldown rates will eventually equalize.)
1 The CVL heat loss was doubled between Cases 5 and 6, and again between Cases 7 and 8. The increased CYC heet loss obtained a more-negative initial CVL flowrate and an increased delay until CVL fl ow reversal.
The transient RVUH cooldown rate was littis affected by these CVL heat loss changes.
( The MIST CVL orifice hydraulic resistance was approximtely doubled between Cases 6 and 7; the former rosistance was the target value, the latter wa:
[.
extracted from the orifice calibration data. This resistance change
[ decreased the magnitude of the CVL fl ow rate generally, as would be expected, and thus reduced the RVUH cool down rate (during the first half-hour of the imposed cooldown).
On the basis of the CVL flow reversal alone, Cases 7 and 8 bracket the plant reversal time - it would appear that with the MIST actual character-istics (elevations, CVL fluid and metal mass, and me asured orifice resistance), MIST would approximate the plant fl ow reversal time if the MIST CVL heat losses were set to approximately 15 watts at 600F.
A-10
i . .
HI il Considering the rate of RVUH cooling during the first hal f-hour of .the transie nt, the lowest CVL heat loss appears preferable; but the initial MIST RVUH cooldown rate will necessarily lag that of the plant, because of
! the smaller flow' rate in the MIST CVL.
La LI I
lI lI
~
I
!,I
-l ,
l.
I
,o
'I
'g A-ll
!g .
g .
[
6.0
SUMMARY
{
The plant CVL performance is characterized by:
o Downflow in the continuous vent line at steady state.
p o A few-minute delay until CVL flow reversal to upflow.
L.
[ o An increasing rate of RYUH cooling after upflow has beer. established in the CVL.
I Each of the MIST predictions has evidenced all three of these performance characteristics. None of the MIST inter-case changes (altered CVL orifice resistance, and CVL heat losses to ambient from 5 to 20w) has obliterated any of these CVL performance characteristics. Regarding the extremes of CVL heat loss, some loss (-Sw) is required to obtain dow'nflow in the vent line at steady state. And an arbitrarily large loss will suppress the CVL flow reversal (during an imposed cooldown) and correspondingly delay the start .of RVUH cooling. (Noting the plant results, Section A.4, the ef fects of an increased CVL heat loss to ambient can be overwhelmed by increasing
( the imposed cooldown rate.)
E A-12 W - -
7 TABLE A.1 CVL CONFIGURATION
/'
Parenthetical entries denote MIST characteristics approximately equal to
'l those of the scaled plant. Underlined entries denote notes and references (following table).
MIST /
Characteristic ElRDj; Scaled Plant ELE Scaled Plant
.t (S = 817)
Yac1Lcal Lengths, ft l.
Ig - RVUH, HL nozzle to 12 (L) 7.8(i) 0.65
!g top of RVUH
' ' - CVL, RVUH to SG 51.5 (D 23.4 (L) 0.45 Inlet Plenum
, 2. CVL Weichts, lbm
- Fluid 182.5(2) 0.223 1.623 (1) 7.3
- Metal 1236 (L) 1.513 35.7 (1) 24 ,
f
3. RVifH Weights, Ibm
- Fluid 33.9 (i) (33.9) (1)
- Metal 0.402(1) (0.402) (1)
4. Mass X Soecific Heat, Metal & Fluid, BTU /F
- CVL 0.449 (1) 6.23 14
- RVUH 64.8 (1) (64.8) (1)
5. CVL Heat less To Ambient @ 600F, w 3860 (1) 4.724 (To Be Determined) ;
l
6. Hydgaulic Resistance,
'K/a , HL Nozzle to SG Inlet Plenum, ft-4
- Via HL 3000 (1) -3000 (1) t
- Via CVL 1.76x1010(d) -5.5x1010(E) 2 l ll l
'I ;
I i A-13 l
[
Table A.1 (Continued)
{
h NOTES
1. Ref.: 86-1152752-00, " Design Inputs For MIST RV Head Vent To Hot Leg,"
June 25, 1984.
{
3
2. Corresponds to -106 ft. of 2 1/2" Pipe With p (Fluid Density) = 50 lbm/ft ,
[ 3. Ref.: 86-1152752-01, June 26,1984.
4. Ref.: MIST Facility Specification (With Appendicies), RDD:84:4091-01-01:01, s Distributed November 1984.
{
5. Used Metal-C - 0.12 BTU /lbmF, Metal-fp - 60 BTU /FY3F, Fluid (Water) o
-Cp - 1.2 B /lbmF.
6. Ref.: 32-1153982-00, " MIST Continuous Vent Line," March 5,1985 (Section 3.2 " Resistance").
7. Corresponds to 27.4 Feet of 1/2 in-Schedule 160, Fluid Density -50 lbm/ft 3, l
8. Extracted From "... Vent Orifice ... Report...," F. Karimi-Azad Meco Dated September 24, 1985. ,
l
[ .
[
[
[
[
[ A-14 S
L
[
TARIF A.7 IOGIC USED TL DdTERMINE CVL PERFORMANCE
( l. Set and print inter-case variables.
2. Initializs (loop flow, loop fluid temperatures, and CVL flowrate).
3a. Set time, update time-dependent boundary cond'itions (core power and SG
= cold leg fluid temperature).
( b. Update loop conditions (fluid temperatures and densities)
4. Determine CVL flowrate to balance loop and CVL differential pressures.
[. 5. Determine CVL fluid temperature and density by heat balance.
6. Determine RVUH fluid temperature and density by heat balance.
[ .
7a. Check convergence of CVL flowrate (compare iterative change to 0.1% of the prevailing flowrate). If not converged, repeat #4-7. l l
b. Store results.. ,
l 8a. Check steady state (compare the change over the last one-minute time increment to 1% of the current CVL flowrate). If unsteady, repeat #3-10.
b. Advance time. If the current time is less than the (input) end time,
( repeat #3-8.
9. Print results versus time.
[
[
[
[
[
[
C A-15
L
[
TABLE A.3 CODF LISTING
[
2 REM CONTINUOUS VENT LINE (C.V.L.) PERFORMANCE, 24FEB86
[ 3 4
REM REM (2100) 6 REM DIMENSION PRING VARIABLES...
10 DIM PT(100), PQ(100), PC(100)
[ 20 DIM PF(100), PH(100) 30 DIM PP(100), PM(100), PY(100) 40 DIM PU(100), PR(100)
[ a REM f0 OPEN1,4 55- C101 57 EPS = 0.1
[ 58 T = -l 80 REM OK= STEADY-STATE KEY, @ UNSTEADY...
85 OK = 0
( 90 REM 100 REM SET INTER-CASE VARIABLES 10 2 REM----------------------
104 REM START, INC, & END TIME (MIN)=T,DT,TE
[ 107 DT = 1.
108 TE = 90 110 REM RVUH, CVL, & HL VERT LENGTHS (FT)=ZU,ZY,ZH
[ 112 ZU = 12 114 ZV = 51.5 116 Z:1 = ZU + ZV 118 REM CD = (SG AND COLDLEG) COOLDOWN RATE, F/HR
[ 120 CD = 100. '
125 REM TC = TCOLD, F ,
130 TC = 550
[ 135 REM Q = CORE POWER, %
140 Q =2 145 REM KV = CVL HYDRAULIC RESISTANCE (K/A 2), FT -4
( 150 KV = 1.76*10 10 155 REM QW = CVL AMBIENT HEAT LOSS, W
! 160 OW = 4.72 165 REM MV = CVL-REGION MASS X SP.HT., BTU /F
[ 167 MV = 0.449 169 REM MU = RVUH-REGION MASS X SP.HT., BTU /F 171 MU = 64.8
( 173 REM Cl & C2 = CONSTANTS IN DP-VS-FLOW...
175 C1 = SQR(64.4*144. )
176 C2 = 3000*0.46*0.46/(64.4*144)
[ 177 PRINT 180 PRINT "C A S E D E S C R I P T I O N" 182 PRINT "------ - - - - - - - ' "
186 PRINT " TIME INCREMENT, M =";DT
[ 188 PRINT " END TIME, MIN =";TE 190 PRINT " C00LDOWN RATE, F/H =";CD 192 PRINT " COLD LEG TEMP., F =";TC 194 PRINT " CVL HYO RES, FT -4 =";KV
{ 196 PRINT " CVL Q-AMBIENT, W =";CW
[ A-16
Table A.3 (Continued)
{
l
( 198 PRINT " DZ, N0Z-TO-RVUH, FT=";ZU 200 PRINT " DZ, RVUH-TO-SG, FT =";ZY 214 REM 216 REM 2. INITIALIZE
{ 218 REM - - - - - -
220 REM F = LOOP FLOW, %
r 222 F = 3 * (0/2) 0.333 L 224 REM TH = HOT LEG TEMP, F 225 REM RH = HL FLUID DENSITY, LBM/FT3 226 TH = TC + 50*Q/F
[ 228 REM RH = HL FLUID DENSITY, LBM/FT3 230 RH = 14.723*(705.5-TH) 0.225 l
235 REM RV,RU = CVL, RYUH FLUID DENSITY, LBM/FT3 240 RV=RH : RU=RH
[ 245 REM VO,00 = (PREVIOUS) CVL, RVUH FLUID TEMP. F 250 REM 2ND CHARS 0,1,2, = PREVIOUS, CURRENT, AND T-MEAN VALUES
- 255 VO=TH : Vl=TH : V2=TH
[ ,
260 UO=TH : U1=TH : U2=TH 275. REM MO,MP,M1 = PREY, TENT,NEW CVL FLOWRATE, LBM/S 280 M0=0. : MP=0. : M1=0.
285 REM
[ 300 REM 3. TRANSIENT, LOOP SOLUTION 3 0 2 REM ------- ------ ----
.302 REM
[ 306 REM II IS TRANSIENT C0tJTNER 30:; II = 0 g
310 II = II + 1 312 IF II)100 THEN 910
[- 315 REM BEGIN RAMPS AFTER TIME ZERO 320 IF T<0 THEN 403 r 325 REM CORE POWER (Q,%) DECAY
( 330 Q = 2 - T/60 335 REM SG & TCOLD C00LDOWN l 340 TC = 550 - T*CD/60
[ 345 REM (NO FEEDBACK, CVL TO LOOP) 350 F = 3 * (Q/2) 0.333 355 REM TH = HOT LEG FLUID TEMP, F r 360 TH = TC + 50*C/F 365 REM RH = HL FLUID DENSITY, LBM/FT3 L.
370 RH = 14.723*(705.5-TH) 0.225 398 REM
[ 400 REM I T E R A T I O N 401 REM - - - - - -
402 REM 403 PRINT E-. 404 IF OK=0 THEN PRINT " ITERATING FOR STEADY STATE, TRY #";II i 405 IF OK=1 THEN PRINT " ITERATIONS AT TIME (MIN) = ";T 406 PRINT" I MERROR(%) CVLFLOW(LBM/S) T-CVL(F): T-RVUH(F):"
( 409 REM HL-IRRECOVERABLE PORTION OF CVL DP, PSI 410 IR = C2*F*F/RH
[ -
A-17
_ _- __________m_ - - - _ - _ - _ _
[ .
Table A.3 (Continued)
{
411 FOR I=1 TO 20
[- 412 REM 413 REM 4. CVL FLOWRATE 414 REM --- --
415 REM DP=CVL ORIFICE DP, PSI
{ 420 DP = IR + (ZH*RH-ZU*RU-ZV*RY)/144 425 REM MP IS TENTATIVE CURRENT FLOW 430 MP = 0, b 435 IF DP>0 THEN MP= Cl* Sat ( RV*DP/KV) 440 IF DP<0 THEN MP=-Cl*SQR(-RY*DP/KY) 445 REM M2 IS CVL MDOT OVER DTIME
{ 450 M2 = (MO+MP)/2 455 IF II=1 THEN M2=MP '
460 MA = ABS (M2) r 470 REi4 L 500 REM 5. CVL HEAT BALANCE 502 REM -- - - - - - -
505 REM QA IS CURRENT CVL LOSS, BTU / MIN l
[ 507 REM (ASSUME LINEAR FROM OW(T=600F) TO O AT 100F...)
510 CA = (3.412*0W*/60)*(V2-100)/500 515 REM ASSIGN FLUID TEMP CONVECTED IN r 520 REM BASED ON CVL FLOW DIRECTION l L 525 IN = U2 530 IF M2<0 THEN IN = TH 535 REM NEW TEMP (VI) = OLD (VO)
[ 540 REM + Q-CONVECTED IN - AMB. LOSS 545 V1 = VO + (DT/MV)*(60*MA*(IN-V2)-QA')
550 IF Vl<100 THEN Yl=100 551 REM CVL-REGION TEMP OVER DTIME, F 552 V2 = (V0+V1)/2 555 REM NEW CVL DENSITY, RV 560 RV = 14.723*(705.5-V2) 0.225 590 REM 600 REM 6. RVUH HEAT BALANCE 602 REM ------- - - -
{ 610 REM ASSIGN TEMP OF FLUID CONVECTD 612 REM FROM THE DIRECTION OF THE CVL 614 REM FLOW, +=TH, -=CVL r 616 IN = TH L 618 IF M2<0 THEN IN=V2 625 REM RVUH DE SOLEY FROM CONVECTION 630 U1 = UO - 60*DT*MA*(U2-IN)/MU
[ 631 IF Ul<100 THEN Ul=100 632 REM RVUH-REGION TEMP OVER DTIME, F 63? U2 = (UO+Ul)/2 635 REM NEW RVUH FL DENSITY, LBM/FT3 E 640 RU = 14.723*(705.5-U1) 0.225 .
645 REN RVUH COOLING RATE, F/H. . .
650 UT = 60 * (UO-Ul) / DT
[ 690 REM 700 REM 7. CHECK K)0T CONVERGENCE E
A-18
1 Table A.3 (Continued) 7 0 2 REM -----------------
710 ER = 100 * (MP-M1) / MA I 715 ER = INT ( 100*ER)/100 +0.001 716 M3 = MP 717 V3 = INT (1000*V1)/1000+0.001 718 U3 = INT (1000*Ul)/1000+0.001 720 PRINT I;ER,M3,V3,U3 8 73 M1 = MP
~
730 IF I<3 THEN 750 740 IF ABS (ER)<EPS THEN 810 1 750 NEXT I 760 REM END ITERATION g 765 REM -------- -------------
.g 790 REM 800 REM 8. SAVE/ UPDATE VARS, STEP TIME 802 REM --------- ------------------ -
I 810 PT(II) = T 812 PQ(II)= INT (100*( Q&O.005))/100+0.01 814 PC(II)= INT (100*(TC+0.005))/100+0.01 I 816 PF(II)= INT (100*( F+0.005))/100+0.01 818 PH(II)= INT (100*(TH+0.005))/100+0.01 820 PP(II)= INT (1000*(DP+0.0005))/1000+0.001 822 PM(II)= INT (10000*(Ml+0.00005))/10000 I 824 PV ( I I )= INT (100 * ( Vl+0. 005 ) ) /100+0. 01 826 PU(II)= INT (100*(Ul+0.005))/100+0.01 828 PR(II)= INT (100*(UT+0.005))/100+0.01
~
I 830 IE = II 832 IF OK=1 THEN 842 834 REM CHECK APPROACH TO STEADY STATE...
836 IF II<3 THEN 846 I 838 IF ABS ((M1-MO)/M1)>0.01 THEN 846 840 OK = 1 841 REM ADVANCE TIME...
I 842 T = T + DT 844 REM UPDATE VARIABLES...
846 M0=M1 : VO=V1 : UO=U1 856 IF T<TE THEN 310 I 890 REM 900 REM 9. 800ACIOUS PRINT 902 REM ----- -
904 PRINT 906 PRINT 910 PRINT
'E 915 PRINT" TIME Q TCOLD FLOW TH0T CVL-DP -FLOW -TEMP RVUH-T -COOLDOWN" E 917 PRINT" MIN % F % F PSI LBM/S F F F/HR" 920 FOR I=1 TO IE 930 PRINT PT(I); PG(I); PC(I); PF(I) PH(I); PP(I); PM(I);PV(I);PU(I);PR(I) 940 NEXT I
=
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[ , [ - Figure A.2 [. . Two Predictions of Plant CVL Flowrate , jj j yJ A l l l l l l (50F/h System Cooldown) l lp
~
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A-22
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[ - Figuri A.4 [ CVL Flowrates. Various Configurations, 20F/h SG(&CL) Cooldown
!' !i '
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[. , APPENDIX B EXTRACTS OF PERFORMANCE PREDICTIONS t o "DB-1 RV Head Vent Line Transients Analyses," B&W F L Doc. No. 32-1150145-00, February 27, 1984. o "DB-1 RV Head Vent Heat Loss (Task 2)," B&W Doc. No. 32-1149185, i l February 27, 1984. i ( o "DB-1 RV Head Vent Heat loss (Task 1)," B&W Doc. No. 32-1149099-00, February 15, 1984. [ [ [ [ [ [ [ B-1 [ m &m
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[ Appendix C , Predicted LOFW Transient E E E [ [ E C-1 [- =
This appendix provides the case description and results of the predictions { for the Davis Besse LOFW (Loss-Of-Feedwater) transient. This particular [ case has the following characteristics: [ o PORV sized based on the November 22, 1985 test data. o Operator actions 10 minutes after the hot leg temperature reaches 600F.
'o Reactor trips on high pressure.
This appendix repeats B&W Doc. No. 86-1159551-00, " Davis Besse LOFW/ll-22-85 PORY," and is included herein for ease of reference. The pages following provide a detailed description of the case and its initial conditions. A sequence of events is provided in Table 1. Figures l through 11 depict the transient results. These figures are: l { ( l' Primary pressure
2. Core-region collapsed liquid level

3. Hot leg levels

4. Cumulative primary boundary flowrates

5. "A" hot leg and' cold leg fluid temperatures

6. "B" hot leg and cold leg fluid temperatures
(
7. Primary (loop) flowrate

8. Pressurizer collapsed liquid level

9. Void fraction in uppermost pressurizer volume (supplying the PORY and safety)

10. PORY mass flowrate
{
11. Steam generator secondary outlet pressure.
^
[ C-2 [ . w
l [ l PURPOSE: This document transmits the case description, initial conditions, and results for the DB-1 loss-of-feedwater event with reactor [ trip on high .RCS pressure and operation action 10 minutes afher the hot leg- temperature reaches 600* F. The PORY used for this case is the "best estimate" configuration based on 11-22-85 flow { test data. , CASE DESCRIPTION AND INITIAL CONDITIONS Given on the next two pages is a description of the case by ( definition of key parameters of the event. Following the case description are the initial conditions for the event. .l [ ' RESULTS: Figures 1 through 11 are case time histories showing the development of the event. The event begins.at 100 seconds on the time scale with MFW trip. Table 1 gives a sequence of events for the transient. ( The case was terminated after the reactor vessel reached its minimum inventory and refill was in progress. The minimum collapsed l [ water level is 11.9 feet at 3730 seconds which assures that sufficient core cooling is available throughout the event. [ Th'e development of this event is similar to the previous as-built feed and bleed cases. The difference in results from this case and the previous cases stems from a slight change in PORV relief capacity and the time of operator action. The subject case adds ( additional support to the, analyses done previously for plant as-built conditions showing that the system relief and injection capacities are sufficient to maintain core cooling following a { sustained total loss of feedwater. [ [ [ C-3
L-m DB-1 LOFL 11-22-85 PORV CASE DESCR'iPTION F L Initiatino Event - Loss of all feedwater to both steam generators 7 at time = 0 ( transient starts af ter a 100 second steady state) . I L Main Feedwater Valves - Ramped closed in 10 seconds. L ' Auxiliary Feedwater - None Power Level _- 102% of 2772 MWt J Reactor Trio - Activated by hot leg pressure 2.2300 psig. Turbine Stoo Valves - Closing delayed 0.5 seconds af ter reactor trip and then ramped closed in 1.0 seconds. _ Turbine Bvoass - None Makeuo Plow - One pump is functional at start of event with second pump started 15 seconds after reactor trip; actuation if pressurizer level falls below 198". EQE - Functional at start of event with opening at 2450 psig and closing at 2400 psig. Valve area is 0.013 ft 2. A discharge coefficient of 0.759 was applied'to flow path based on 11-22-85 Duke Power flow test data and line losses. Pressurizer Vent - Single vent with area = 8.3 x 10-4 ft 2 and CD
= 0.53.
Hiah Point Vtat;.g - Two vents each with area = 2.0 x 10-4 ft2 and [ CD = 0.53. Pressurizer Safetv Valves - Two valves available, each with { 350000 LBm/Hr capacity to open at 2500 psig and close at 2425 psig. C-4 ~
E L i L DB-1 LOPW, 11-22-85 PORV CASE DESCRIPTION (cont'd) L Let Down - Isolated on reactor trip. Onerator Action - Taken 10 minutes after RCS hot leg temperature reaches 600 *F. Operator opens two high point vents and pressurizer vent, blocks open the PORV, and locks open makeup flow control. Operator trips reactor coolant pumps when subcooling margin is less than 20* F. <. , Decay Heat - 1979 ANS 5.1 Standard Secondarv Pressure Control - Pressure controlled by main steam safety valves after reactor trip. [ [ [ ( [ [ [ ' C-5
DR-l_LOPW, 11-22-85 PORV CASE INITIAL CONDITIONS
, gg, actor Coolant System Pcwer Level 2827.44 MWt i
( Pressure 9 Hot Leg Sensor 2173 psia l Total System Flow Rate 42060 LBm/Sec Th 607'F { Te 560*F Pressurizer Level 198 In. Seconda ry System - [ Main Feedwater Flow Rate /SG 1705 LBm/Sec Feedwater Inlet Temperature 460*F Stean Outlet Temperature 565'F Turbine Header Pressure 900 psia Steam Generator Level 170 In. e [ m C-6
TABLE 1 SEQUEFCE Ol' EVENTS b I Event Time, see after LQM i
't Loss of Feedwater 0.0 Reactor Trip 15.25 Turbine Trip 15.75 Hot Leg Temp. 8 600'F 96 Operator Action ,696 PORV Blocked Open High Point Vents Opened Przr Vent Opened -
15 Switch Makeup control from Level to Demand RC Pumps Trip 705 . dot Leg Void of Liquid A loop /B' loop 2800/2500 RCS Depressur),zation Begins 2850 Minimum Total Core Collapsed Liquid - 11.9/3730 I Level, Ft./ Time II
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!i 1 l 5 Appendix 0 ~ MIST Simulation of Davis Besse Cnaracteristics (Test 3703) I i I . B I ( .I' I
?
l --
s H The Davis Basse characteristics are converted to MIST while retaining the L standard MIST scale factors, notably 1% of scaled full power = 35 kw and. the predominant (power and volume) scale factor, S = 817. Three Davis Besse systems are involved: t
1. Core power,

2. HPI/MU, and

3. Discharge arsas.
L Core Power Davis Besse generates 2772 mw at full power, versus the plant full power of 2700 mw upon which MIST is based. Also, the RELAP case being simujated used an initi al power level of 102% of full power. Finally, the assutaptions used to generate the decay power schedule for the code case g differ somewhat from those used in MIST. These three differences between the Davis Besse simulation and the generic MIST assumptions obtain an increased coro decay power fo- this simulation of the Davis Besse LOFW transient. The calculation of MIST scaled core power level (in percent of -- 2700 mw, and in kw) frem the code model data is shown in Table D.l. , L The standard and revised MIST power schedules are shown in Figure D.1. F L HPI/MU The Davis Besse high pressure injection (HPI) and makeup (MU) flowrates are both to be simulated using the MIST HPI system. The MIST flowrates are cbtained by dividing thi plant flowrates by the. MIST (power) scale factor of 817. The plant pressures are reduce ( by 100 psi to compensate for the lower PORY setpoints in MIST. These conversions are illustrated in Table D-2
ir-I KB
r. D.2 and Figures 0.2 and D.3. The HPI is assumed to be supplied suction from the LPI system (the " piggyback" mode), and the MU system flowrates 7
include a minor contribution for seal injection flow. Both the HPI and MU flowrates are for two pumps operating (in each system). r' l Plant makeup is injected to a single (A1) cold leg, through the HPI nozzle, while HP is directed to all four cold legs. This di fference between injection schemes will be simulated in MIST by injecting (makeup) through only the Al NPI nozzio, until the primary pressure first decreases
, below approximately 1700 psia. When primary prissure first decreases below 1700 psia in HIST, transfer from single-loop injection to injection through all four nozzles and retain this configuration fer the duration of the I' transient.
Modify this transfer pressure to maintain the Al-HPI flowmeter within its calibrated range. At lower pressures (approximately 1500 psia), modify the HPI characterist'ics to observe the MIST HPI capacity and meterirg limits. Discharce Areas MIST uses critical-flow crifices to obtain the scaled discharge flowrates of the plant equ1pment being simulated. Virtually every discharge stream is activated during the transient of interest. These streams are listed in tablo along with their flow areas from the RELAP input model.
!I Discharge coefficients are used to adjust the flowrates calculated by RELAP toward those obtained from testing. Therefore, a more appropriate MIST !m D-3 ig 'I g -
r il 18 flow area is that which (when scaled) will obtain the scaled discharge flowrate predicted by RELAP. This consideration obtains the second column of entries in Table D.3. The Modified Curnell predictions of (subcooled) critical flow, when multiplied by 6.85, have been found to approximate t those observed in previous integrel system testing, thus this correlation and multiplier were cpplied to obtain these critical-flow areas. Multiple pressures and subcoolings were encountered with the PORY manually open during the RELAP prediction, obtaining a range of MIST flow areas appropri-ate for the predicted flowrates. These PORY flow areas ranged froa 11 to 20 cm 2. No such range of conditions was available for the safeties, l f therefore a single MIST-equivalent safety valve flow area of 64 cm2 was 7 obtained. MIST currently has a PORV flow area of 10 cm 2, no simulation of safeties or a pressurizer vent, and hot leg vents of 1 cm 2 each. A safeties simulation (of -64 cm2 critical flow area) should be added to MIST. The PORV flow area should be increased to roughly 16 .cm 2 , both to better-simulate the f plant PORY and to include the contribution of the plant pressurizer vent, g The flow areas of the MIST HL vents shoul d ideally be reduced to g 2 cr larger l approximately 0.2 cm2 each, but are limited to roughly 0.75 cm by machining constraints -- a flow a rea of 0.75 cm2 at pl ant scale j corresponds to a hole diameter of 0.0135 inches in MIST. The aforementioned PORY and vent changes may be cmitted without apparently I degrading the usefulness of the test transient. But some sort of safety valve simulation must be included in MIST, in order to generate the D-4
.I I
1 long-term repressurization and ultimate depressurization phases of the transient of interest. The MIST two-phaso vent system was designed to [ handle at least 50 cm2 . The proposed total flow area of 80 cm 2may exceed t the physical heat removal capacity of the installed two-phase vent system. If the two-phase vent cooler outlet temperatures indicate an unacceptable haatup during testing, it is suggested that the test be aborted, and then L rerun with a suitably-modified core power decay schedule. ? - E r [ D-5
r TABLE D 1 MIST CORE POWER. TEST 9703 L I L F
REACTOR TRIP P0hER VS TIME TABt.E
{ 20200600 POWER 519 l o ////JN/bO POWER f Mk 1 M /hid /> 3 _ _ _ . _ . . T I M E .L_S E C . . ) VS 20200601 -1.00 - 2827.44 / OV .7 THW li o Y > )_ . 20200602 0.50 2827.44 I 20200603 0.60 2676.90 ' 20200604 0.70 i 2567.57. 20200605 0.80 :'/,,.(ffg.3,) 2458.37 g r 20200606 _0. 10 __2349.00 ., . . . . . . ._ . . . 20200607 1.00 - l. '772' 2240.0 ' f; ,7 p 20200608 1.50 -I.(,>0- ~ ~ ~1199'.71 a->
~202006'09 ~ ~ ~ 2 '.'5'0 "~ -~.'_ /. U ' C,.~~ 566.65 : s , $* ~"
20200610 3. 5 0 .. . --/ l.Lh . . ._3 9.3 . 5 5_ __ , . .' t . _ ;.'. . _ . _ _. . L 20200611 4.50 1 -/, / 21,' 356.20 c . /1 20200612 .6.500
-0.f/J..i'.. .__. 312. 6 0 // ~h,. t4,'6 y / . _, 2.(' /., .
c 20200613 10.50 -0. 7 f'/ 266.46 ' ' - 20200614 _12.50___ . - .hl, k]4_ _ 2.44 83 I _7,9 '_Qf_f.__.
~20200615 2 0.~ 5 0 - o, gf 214.43 e .26lN..'/
20200616 24.500 ._- ,Mf9_ 200.63 /.N j p 3 _.. 2 4'M P . _ . 20200617 40.500 ' _o./ -r / 157.86 f,8V7 . H2 7 20200618 48.500 -n,J d.2.h__ _13_7.87.. .. S~ / J 6 ; /4',.." 20200619 100.50 to,2 24/ 103.54 ; J, 9 35~~ ! / 2 6. .-i~~ r __20.200620 120.50... c. g .o_3._ . . 92.340 4
?.4 2 > i // ; 1 vs L 20200621 200.50 o.g2 4 80.04 , :.9ev -
1.;.q./ 7 _202006_22 240.50 75.41 3
!,71.3 . .
20200623 400.50 3 ' O.6 2c_ : ' 3[ 67.01 l' /2. b, !! .?
~ O ' e-20200624 1000.5 /,422 54.54 ~
i 66 66
~20'200 62 5 2000.5 /, #)f3 ,' 44.90 ~ j /,55 5 iSy,g'( ;/,:(f,,; .b }
g
................... m...................................................
[ E D-6
g TABLE D.7 MPI + MU (TEST 3703) Note the MIST pressure and flowrate entries in the right-hand columns. See text for discussions of MIST capa illities versus plant-scaled characteristics. p MIST L- .HPI gpm MU gpm MIST = Prassure Pressure (32-1149119-00 (32-1106901-00, Sum lbm/s (Sum /817) (Plant-100) esta o. 9) o. 5) ggn_ (Note 1) lbm/s osia 200 1820 600 2420 335 0.410 100 400 1720 580 , 2300 318 0.389 , 300 600 1600 550 2150 297 0.364 500 1 800 1470 530 2000 277 0.339 700 1000 1330 500 1830 253 0.310 900 1200 1170 475 1645 228 0.279 1100 - 1400 590 450 1440 199 0.244 1300 L 1600 740 420 1160 160 0.196 1500 { ' 1800 300 380 680 94.1 0.115 1700 1816 0 375 375 51.9 0.0635 1716 2000 0 330 330 45.6 0.0559 1900 2100 0 320 320 44.3 0.0542 2000 2200 0 290 290 40.1 0.0491 2100 2300 0 270 270 37.3 0.0457 2200 2400 0 240~ 240 33.2 0.0406 2300 I 2500 0 200 200 27.7 0.0339 2400 2600 0 150 15 0 20.7 0.0254 2500 Note 1: Used m (1bm/s) = Q (gpm)(ft 3/7.481 gal)(62.09 lbm/f t )(min 3 /60s)
= 0.1383 Q D-7 L. - _ _ _ - - _ _ _ _ _ _ _ - _
L TABLE D.3 HIST CRITICAL-FLOW AREAS Areas are shown in unscaled ft2 , parenthetical entries are in unscaled em2 Critical Flow Area Such I That 0.85 X the Critical L Flow Predicted by the Modified Burnell Correla- Standard 7 Plant Flow Areas tion Obtain the Flowrate MIST L pse in RELAP Predicted by REL AP ' Areas PORY 0.0131 (12) (11 to 20) (10) Safetics 0.0457 (42) (64) NA (two combined) ~ HL Vents (each) 1.97 x 10-4 (0.2) --- (1) Pressurizer 8.30 x 10-4 (0.8) -- NA [ Vent r L I~ L - E [ [ - [ D-8 [ ____--.__k---.___-_--
{,. . _ , _ . , - , - - . - - - ..- - . - ...:---- - - - 1
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ML20203M020: Difference between revisions

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ML20203M020: Difference between revisions

Latest revision as of 07:44, 31 December 2020

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1.0 INTRODUCTION

6.0 REFERENCES

1.0 INTRODUCTION

6.0 REFERENCES

1.0 INTRODUCTION

SUMMARY

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