ML20085L070

Forwards Responses to Giraffe Sys Integral Testing RAIs 900.96-900.101

ML20085L070
Person / Time
Site:	05200004
Issue date:	06/23/1995
From:	Quinn J GENERAL ELECTRIC CO.
To:	Quay T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
MFN-093-95, MFN-93-95, NUDOCS 9506280285
Download: ML20085L070 (8)

Text

)

O:

GENuclearEnergy

~\\

l YMR

$s 75 C ne en

$165 San Jose, CA 95125-1014 B

P 408 925-1005 (phone) 408 925-3991 (facsimile)

June 23,1995 MFN 093-95 Docket STN 52-004 Document Control Desk U. S. Nuclear Regulatory Commission Washington DC 20555 l

Attention: Theodore E. Quay, Director Standardization Project Directorate

Subject:

SBWR - Responses to GIRAFFE SIT RAIs 900.96 - 900.101

Reference:

1.

Letter from J. H. Wilson (NRC) to J. E. Quinn (GE), REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING THE SIMPLIFIED BOILING WATER REACTOR (SBWR) DESIGN - SYSTEMS INTEGRAL TESTING AT GIRAFFE TEST FACILITY (Q900.96 - Q900.101), dated May 24,1995.

Attached to this letter are the responses to the Referenced letter on the schedule which NRC requested. The final details of the tests are not yet fixed in some cases, so we have provided the best available information which we will update to you as appropriate.

Sincerely, hlNLAM w

James E. Quinn, Projects Manager LMR and SBWR Programs

Attachment:

Responses to Open Items identified in May 24,1995 NRC letter cc:

P. A. Boehnert (NRC/ACRS) (2 paper copies w/att plus E-Mail w/att.)

i

1. Catton (ACRS)

(1 paper copy w/att. plus E-Mail w/att.)

S. Q. Ninh (NRC)

(2 paper copies w/att. plus E-Mail w/att.)

J. H. Wilson (NRC)

(1 paper copy w/att. plus E-Mail w/att.)

t 2700s.;

fi'D i

9506280295 950623 PDR ADOCK 05200004 A

PDR

L l

Attachment to MFN No.

Responses to Open Items identified in May 24,1995 NRC letter:

REQUEST FOR ADDITIONAL INFORMATION (RAI) CONCERNING SIMPLIFIED BOILING WATER REACTOR SYSTEMS INTEGRAL TESTING IN GIRAFFE 900.96 GE and the staff have discussed the scenarios for the four tests that will comprise the " Systems Interaction" tests (SIT) in the GIRAFFE facility. Provide written confirmation of the tests selected, including revisions to Table A.3-21 in Rev. B.

RESPONSE TO 900.96 Written confirmation was provided on May 24,1995 in MFN077-95, which included markups of Table A.3-21 in TAPD, Rev. B. Four tests will be conducted. In a telephone call on May 30,1995, NRC agreed with this confirmation.

1 i

1

1 900.97 Ilow will initial conditions be established in the test facility at about 100-150 psi, and how will the tests be started? In this regard, what assumptions will be made j

in the use of TRACG to help establish initial conditions, and what sort of facility l

characterization data will be acquired to validate the TRACG GIRAFFE model l

and to assist in performing the TRACG calculations?

HESPONSE TO 900.97 These responses generally describe facility operation and are tentative until detailed procedures are developed.

Facility Operation. Since the GIRAFFE facility simulates only the final stages of the reactor pressure vessel blowdown (i.e., less than 150 psia), the following pretest procedures will be used to enable the facility to capture the important reactor system transient blowdown conditions at 150 psia and below. This will be accomplished by initially setting the containment parameters at the conditions associated with the vessel at 150 psia during the blowdown using procedures similar to those used during the IIelium test series. An outside steam (the laboratory house boiler) source will be used to establish initial containment conditions. With the RPV water level above the starting level for the test, the vessel heater rods will be used to get the vessel to its initial pretest conditions (i.e., pressure and temperature). From a pressure of 150 psia, the RPV will blowdown to the drywell by simulating the break flow and the ADS (combined SRV and DPV) flow.

Initial Conditions. The initial conditions for the vessel and containment for the four tests will be derived from TRACG analysis of the SBWR case to be simulated by GIRAFFE (e.g., a GDCS line break with a failure of one DPV). The initial conditions of primary interest are the pressures and water levels in the RPV, wetwell, and drywell.

As noted in TAPD, Rev. B (Section A.3.1.7.3), the containmer.t initial conditions will be based on the conditions of the drywell and wetwell during the blowdown when the vessel is at 150 psia. These parameters can be taken directly from the SBWR TRACG results. One exception is GDCS pool temperature discussed in the response to RAI 900.99.

The RPV initial conditions are to be based on the conditions of the vessel during the blowdown when the vessel is at 150 psia. Since there is a two-phase mixture in the vessel due to flashing from depressurization, the chimney level cannot be taken directly from the TRACG results. Use of the SBWR collapsed downcomer level also is not appropriate since upwardly flowing steam causes more mass to be in the chimney / core regions than would follow from simply matching the SBWR and GIRAFFE downcomer collapsed levels. Given these difficulties, the chosen approach will be to set the pressure at full scale, and the level by scaling the total liquid mass in the RPV. The liquid mass for GIRAFFE will be scaled from the SBWR prediction based on the SBWR to GIRAFFE volume ratios for each RPV region (downcomer, guide tubes, lower plenum, core region, and chimney region). For example, if the SBWR to GIRAFFE volume ratio for one region is 390 to 1, the contribution to the total initial mass in GIRAFFE considering that region will be 1/390 of the value calculated for SBWR at 150 psia.

The mass from each region will be calculated in this way and the sum will determine the total 2

in!tial mass for GIRAFFE. Then the initial vessel level for GIRAFFE will be establish the required initial vessel liquid mass. As a result of this procedure, at the start of the test, the GIRAFFE downcomer collapsed level will be higher than the SBWR downcomer collapsed level, and the GIRAFFE chimney / core collapsed level will be lower than the SBWR chimney / core collapsed level. Shortly after test initiation, when upward steam flow is caused by depressurization induced voids, the mass distribution in the test should be representative of the SBWR case.

Facility Characterization Data. Only the characterization tests necessary to quantify specific facility characteristics which have not been determined from previous tests will be performed lleat loss data from the Ifelium series tests will be used. Additional piping pressure drop tests for the isolation condenser lines and other lines used to simulate liquid breaks will be performed.

Starting the Tests. The tests will be started as follows:

1. Establish the initial containment and RPV conditions (pressure, temperature, water level) as noted above, under Facility Operation and Initial Conditions. The RPV water level will be above the initial starting level and the RPV heaters will be on.

2. Turn the RPV heaters off.

3. Drain the RPV to the starting level (based on liquid mass scaling, noted above).

4. Simultaneously open the valves which:

a) Simulate ADS (SRV + DPV) flow, b) Simulate break flow (GDCS or BDL).

5. At the same time as step 4, turn on RPV heaters to match the decay heat / fuel stored energy cun e.

3

. 900.98 How will operation of the ADS be simulated; i.e., how will the SRVs and DPVs be represented; how many will be open at the start of the test and how many will open during the test; and on what signal will those to be opened, actuate?

' RESPONSE TO 900.98 For the 4 cases to be simulated, TRACG analysis indicates that all DPVs (six for GDCS valve failure cases and 5 for DPV failure cases) and all eight SRVs are open before RPV pressure decreases to 150 psia.

The GIRAFFE facility simulates SRVs and DPVs by blowing steam from the RPV to the drywell through a single orifice in the " GIRAFFE /DPV" line, sized to represent SRV plus DPV.

flow for the single equipment failure being simulated. Each' test will start by opening a single valve to initiate the blow down flow. The valve will remain open throughout the test.

t b

)

i

+

1 i

l l

)

l 4

w W

e

'%e.s T

r 9

+ -+'

y w

f--

r

950.99 Ilow will heat losses in the facility be measured, characterized, and compensated?

Will "microheater" powers be measured and recorded with the data?

RESPONSE TO 900.99 IIcat loss data from the GIRAFFE lie heat loss characterization tests will be used. The SIT tests are short-term tests which focus on RPV performance rather than containment performance, and iieat losses are much less important than they are in the long term containment response.

The GIRAFFE lie heat loss data was generally obtained as follows. The several test vessels (GDCS pool, drywell, wetwell and RPV) were heated to temperatures representative of those expected during the tests. Microheaters (on the surface of the three containment vessels) and core heaters (in the RPV) were then adjusted so that the vessels remained at a steady state temperature. The heater power necessary to maintain steady state is the heat loss for the individual vessel. These tests were discussed in detail with NRC's Jack Kudrick in early June, 1995. See the apparent test results for the tests.

In the SIT tests, microheater power for the containment vessels will be set at the values determined from the lie tests, adjusted for expected vessel temperature differences between the Ile and SlT tests. Should microheater power be insufficient, the power will be set at the maximum value. Power will remain constant and will be measured and recorded with the data.

IIcat loss from the RPV will not be compensated for with heaters for two reasons. First, using core heaters would distort the heat input in the core region and disturb the two phase mixture.

Second, using microheaters on the lower plenum would introduce steam at an incorrect location.

Non-representative heat loss from the RPV will be compensated for by increasing the GDCS pool water temperature so that the lower plenum inlet subcooling is approximately correct.

5

900.100 Will any additional instrumentation be installed in GIRAFFE for the SIT? Does adequate instrumentation exist (or will it be added) to be able to measure water levels in the downcomer and in the " core / chimney" region of the vessel? What will be the sampling rate ofinstruments during these transients? GE also should define the " critical instrumentation" for each test.

RESPONSE TO 900.100 Additional Instrumentation: This information will be provided by July 13.

Water Level Measurement: This information will be provided by July 13.

1 Samnling Rate: The sampling rate is one hertz.

l Critical Instruments: In the SBWR testing program, critical instruments are those which should be available at the beginning of a test, or the test will not be conducted (unless a non-conformance report concludes otherwise); and which must function throughout the test. or the test will be considered invalid (unless a non conformance report determines otherwise).

For the SIT tests, some instruments are needed to establish initial conditions. After the test starts, their importance decreases. We therefore divide critical instruments into 2 categories.

Initial Condition Critical Instruments. These instruments should be available at the beginning of the test. Should they fait during the test, the test is not invalidated. These instruments are:

Wetwell total pressure Suppression pool temperature (one in top half of pool, one in bottom half of pool)

PCC pool temperature (one of two)

GDCS pool temperature Critical Instruments. Since data from these instruments will be used in TRACG qualification and in interpreting test results, they are considered critical and should be available throughout the test.

RPV pressure RPV water levels (downcomer, chimney)

Core heater power Drywell total pressure Wetwell total pressure GDCS pool level Microheater power levels GDCS flow rate GDCS pool temperature PCCS inlet steam flow rate IC inlet steam flow rate 6

)

lI' f

I r

950.101 For ease ofinterpretation, it would be useful to have post-test plots of the data covering just the first hour of the tests, in addition to plots covering the entire 1

duration of the tests.

{

RESPONSE TO 900.101 Plots will be provided in this manner.

t I

i l

t 7

__.