NSD-NRC-97-5180, Forwards W Response to NRC RAI Re Core Makeup Tank Level Instrumentation Roadmap Which Closes Two Open Items Related to Chapters 21 & 14 of Sser

Forwards W Response to NRC RAI Re Core Makeup Tank Level Instrumentation Roadmap Which Closes Two Open Items Related to Chapters 21 & 14 of Sser

ML20141A316
Person / Time
Site:	05200003
Issue date:	06/12/1997
From:	Mcintyre B WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:	Quay T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NSD-NRC-97-5180, NUDOCS 9706200222
Download: ML20141A316 (4)

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l' Westinghouse Energy Systems Ba 355 Pinsburgh Pennsylvania Ib230-0355 Electric Corporation l NSD-NRC-97-S il:0 DCP/NRC0913  !

Docket No.: STN 52-003 June 12,1997 ,

l Document Control Desk  ;

il.S. Nuclear Regulatory Commission Washington, DC 20555  ;

ATFENTION: T. R. QUAY SUl3 JECT: CORE MAKEUP TANK (CMT) LEVEL INSTRUMENTATION ROADM AP l

Dear Mr. Quay:

Enclosure I contains the Westinghouse response to NRC request for additional information pertaining to the Core Makeup Tank (CMT) Level Instrumentation Roadmap. This roadmap closes two open items related to Chapters 21 and 14. Specifically OITS 1626 (DSER 21.5.1-1) and OITS 4198 (RAI 260.90).

OITS 1626 is the original commitment to provide the CMT Level Instrumentation Roadmap, and OITS 4128 is supplemental information supportmg preoperational testing of the passive core cooling system.

This response closes, from the Westinghouse perspective, both open items and the Westinghouse status column will be changed " Closed". The NRC should review these responses and inform Westinghouse of the status to be designated in the "NRC Status" column of the OITS.

Please contact Eugene J. Piplica on (412) 374-5310 if you have any questions concerning this transmittal.

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f3rian A. McIntyre, Ma ager M fox Advanced Plant Safety and Licensing

/ea Enclosure sU cc: W. C. Iluffman, NRC (Enclosure 1)

A. Levin, NRC (Enclosure 1)

N. J. Liparulo, Westinghouse (w/o Enclosure)

J. Sebrosky, NRC (Enclosure 1) 1- 9706200222 970612 _

PDR ADOCK 05200003 E PDR.

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DCP/NRC0913 June 12,1997 Enclosure 1 Core Makeup Tank (CMT) Level Instrumentation Roadmap Introduction The design of the CMT level instrumentation, as captured by the AP600 Standard Safety Analysis Report (SSAR), Probabilistic Risk Assessment (PRA), and Certified Design Material (CDM), is specified as

" generic", with the specific instrument sensor-type to be determined later. The purpose of this "roadmap" is to describe the elements of the process to select, design, and qualify the actual CMT level instrumentation to be installed in the AP600.

A. Design Certification Testing Testing has been conducted on a scaled full pressure core makeup tank (Reference 1), to assess the various operating phenomena associated with the core makeup tanks. This test facility included two level measurement sensors including differential pressure sensors, and heated RTDs. Although this test was not designed specifically to qualify level sensors for final implementation, the test results provide insights as to potential performance issues with two types of CMT level sensors. ,

The observed performance of the heated RTDs (Reference 2) demonstrates adequate performance over the l CMT operating range that is seen during design basis LOCAs. At higher temperature conditions (above  !

what would be encountered for design basis LOCAs) heated RTDs did not distinguish well between changes in water level and changes in fluid temperature. Although this phenomenon is outside the expected operating conditions for design basis LOCAs where the CMT level instrument is required for ADS actuation, it introduces uncertainties with regard to beyond design basis events where higher CMT temperatures may exist. The test results provide valuable information that can be used in the design and evaluation of the CMT level instruments B. CMT Level Instrument Performance in the SSAR The AP600 safety analysis uses bounding values for the CMT level instrument accuracy and response times. The above test results were used to select appropriately conservative values for these parameters.

C. AP600 Plant CMT Level Testing and Analysis A number of tests and analyses will be performed during the development, manufacture, installation, and operation of the CMT level instruments to verify that the actual instruments used in the AP600 plant application are properly designed, operate properly, and are within the bounds of the safety analysis.

These tests and analyses support the following activities:

- Instrument selection

- Instrument qualification

- Instrument production verification

- Instrument in-plant preoperational verification mi. 1

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2 NSD-NRC-97-5180 ,

DCP/NRC0913 ,,

June 12,1997 Testing and analyses associated with each of these activities is further discussed below:

Instrument Selection The combined license applicant will evaluate various candidate instruments in order to select the CMT .

l level instrument. This process will involve consideration of similar past applications and the need for

. additional testing to confirm that the instrument will meet the bounding SSAR safety analyses assumptions. Test may be performed to support instrument selection in case the instrument selected does j not have operating experience over the range of CMT conditions, including operating pressure /

temperature, water / steam mixtures, CMT drain rates, and turbulent / splashing conditions. An example of such a test is the CMT separate effects test performed as part of Design Certification (see item A above). The scale of the test would be determined based on the objectives of the test.

l Instrument Qualification

$ Qualification of the CMT level instruments entails both analytical and IEEE qualification of the sensors ,

j and applicable electronics modules. l Analytical Qualification l The following analytical calculations will be performed to confirm that the design of the level J

instrumentation is acceptable for the CMT application. These calculations include:

1. An ASME Code Class 1 design report to verify CMT Levelinstrument/ sensor pressure .

boundary integrity under the design conditions defined in the equipment specifications, )

l including specified nozzle loads and design transients, i i l

) 2. A measurement uncertainty analysis,considering elements of the CMT levelinstruments, j to establish that the instrumentation package will provide the required accuracy at all i

postulated operating conditions. j IEEE Qualification The CMT level instruments will be qualified based on IEEE-323 including environmental aging, seismic and flow induced vibration, and environmental effects due to LOCA and MSLB.

Instrument Production Verification Each CMT level instrument will be subjected to proacetion t sts appropriate for the type of instrumentation selected for this application. These tests wi'l include a hydrostatic test of the sensor

- pressure boundary, leak testing of applicable pressure boundary welds, dimensional verification, as applicable, of sensor location and orientation and instrument calibration at nominal environmental conditions.

Instrument In-Plant Preoperational Verification Following construction and installation testing, preep~ anonal tests are performed to demonstrate that equipment and systems perform in accordance with cesign criteria so that initial fuel loading, initial criticality, and subsequent power operation can be safely undertaken. SSAR Section 14.2.9.1.3 provides the preoperati onal testing requirements for the passive core cooling system including the CMT level instrumentation. Specifically, iteras (b) and (1) in this SSAR subsection, identify testing that will demonstrate the operability of the CMT level instruments.

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l In addition, a first plant only test of the core makeup tanks has been specified. First plant only tests are  !

l special tests used to establish a unique phenomenological performance parameter of the AP600 design i l features that supplements the testing already performed for Design Certification and that will not change from plant to plant. Specifically, SSAR subsection 14.2.9.1.3, items (s) and (w) specify hot recirculation

, and hot draining of the CMTs. These tests confirm the operability of the CMT level sensors. These ,

! preoperational tests would need to be repeated if the type of CMT level instrument were subsequently )

changed. l

! The AP600 Certified Design Material for the passive core cooling system specify the certified design commitments, inspections, tests, and analyses, and the acceptance criteria associated with the core makeup tank level instruments. Cenified design commitments include commitments that the CMT level instrumentation is IE and is qualified for a harsh environment and can withstand the environmental conditions that would exist before, during, and following a design basis accident as appropriate.

References

1. WCAP-14132, "AP600 CMT Program - Facility Description Report", July 1994

2. WCAP-14442, "AP600 CMT Level Instrument Test Data and Evaluation Report". July 1995 i

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