ML20039A772

Forwards Power Train - Hybrid Computer Simulation of B&W Nuclear Power Plant. Cross-reference Between NRC 790404 Questions on BAW-10070 & Topical Rept on Power TRAIN,BAW- 10149 Included

ML20039A772
Person / Time
Site:	Midland
Issue date:	12/08/1981
From:	Taylor J BABCOCK & WILCOX CO.
To:	Hood D Office of Nuclear Reactor Regulation
Shared Package
ML20039A773	List: ML20039A772
References
NUDOCS 8112210293
Download: ML20039A772 (8)

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Babcock & Witcox wei.., po.., o.n.,.iion oi i. ion a McDermott company - 3315 Old Forest Road P.O. Box 1260 Lynchburg. Virginia 24505 (804) 3844111 hg '5 d December 8,1981 S.3 D Mr. Darl Hood, Project Manager Consumer Power Co., Midland Project Division of Project Management Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555

Dear Mr. Hood:

Enclosed is a copy of Topical Report BAW-10149 Rev.1, " POWER TRAIN-Hybrid Computer Simulation of a Babcock & Wilcox Nuclear Power Plant".

A copy of the original submittal of BAW-10149 (Rev. 0) was sent to you September 2,1981.

This submittal, Revision 1, provides an enlarged Section 4, Applications describing in detail the code application to accident analysis and providing benchmarking of this version of POWER TRAIN against the one described in BAW 10070.

The submittal of BAW-10149 on September 2,1981 provided information in response to question 4 of a series of questions submitted to us April 4,1979 on BAW-10070, the description of the earlier version of POWER TRAIN, used to provide Chapter 15 inputs and results for 177FA plan ts .

This revision provides inforrtation in response to the remainder of the April 4,-1979 questions. Attached is a cross reference showing where in BAW-10149 Rev. I the information for each question may be found.

( Please transmit this submittal to Dr. Walton Jensen for use in his w~ g review of Chapter 15 of Consumer Power Company Midland FSAR.

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8112210293 8112001 PDR ADOCK 05000329 A PDR

Babcock &Wilcox Mr. Darl Hood Page 2 - December 8,1981 This completes our co.nmitment to you and Dr. Jensen made in the June 25, 1981 meeting on Midland FSAR Chapter 15 accident analysis wherein B&W will address outstanding URC questions on BAW-10070 with the more comprehensive Topical Report BAW-10149.

Very truly yours, THE-B BC0CK & WILC0X COMPANY

' J. H. Taylor Manager, Licensing Enclosure JHTl,TLB:e fc

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Cross-Reference'Between:NRC Questions (4/4/79)

, on BAW 10070 and the Recent Topical Report on POWER TRAIH, BAW 10149.

The questions . submitted to B&W (Steven A. Varga' to James H. Taylor, "R'eview of Topical Report BAH-10070, April 4,1979) pertaining to Power Train are answered by referencing portions of Topical'. Report BAW-10149, POWER TRAIN.- Specifically, the response to each question is referenced in BAW-10149 as follows.

"Information on Prior Responses" Question 1.

Question 1 has been divided into three parts for clarity of the responses.

Q.l.l. The requested description of the plant protective system modeled in

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POWER TRAIN is limited to identification of the trip parameters used. Infor-mation concerning the manner.of considering protective instrumentation response, protectiva system' logic and response, and. controlled component response characteristics have not been presented. Provide a block diagram type schematic of the protective system modeled in POWER TRAIN including all input instrumentation, output control signals, and output controllers."

-Response See Subsection 4.3.1-4.3.6 Figures 4.3, 4.4 and 4.5 0.1.2. "In addition, describe the modeling of the plant control system action that may take place before protective action is initiated. A discussion-of

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the manner in which such action is considered in the slower accident transicnts should also be provided in connection with the' description of the protecti/e system function for these transients."

- -- . _ _ _ . . - _ . = . - _ - - . . -. . --

a i Response See Subsection 4.4.

i Q.1.3. "In the res'ponse to Question 4, reference is made to an ICS system concerning feedwater controls. This aystem, which evidently is part of or interacts with the plant protective system is not described in the report.

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Provide a description of.this system, the normal system functions, and where the system is modeled in connection with POWER-TRAIN analyses."

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Response

The feedwater. system (flowrate., valve AP) does not interact directly with

'the plant protection system (see Section 4.3.4 and 4.3.5). The feedwater system modeled in Power Train is shown on Figure 4.3.

,c Question 2. " Response to' Question 4" Q.2. "The information provided in this response does not respond to the

request made concerning Twi. Idantify the limit information against which j a judgment is reached with respect to Twi for the turbine trip transient.

L This information was requested in the original: request for additional information. It is also requested that the dependence on mass flow rate of the Twi -limit be furnished.

In connection with the sample results shown on Figure B-1, provide the l . following additional information:

Discuss and justify' the apparent lack of cold leg transport delay -

a)

- at the reactor inlet, b) Discuss che apparent transport delay. cccurring -in;the core resulting from the use of a single node core coolant mixing model such as -

, would be obtained from equations 3.3-2'and 3.3-3 in'the report."

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Response

See Section 2.7 for discussion of modeling of reactor coolant tenperatures and flow dependent transport delays.

Figures 4-2, 4-7, 4-18 and 4-19 show the expected and actual transport delays in select' ed temperatures. Judgement about the adequacy of the transport delays is based on comparison of model performance against actual plant data.

Question 3. " Response to Question 7" Q.3. " Describe the valve vendor supplied data used as a basis for determining spray, relief, and pilot valve flow rates, and describe the method used for quantitatively determining these parameters for POWER-TRAIN calculations."

Response

Section 4.3.1 discusses valves represented in Power Train.

" General Informat ka" Question 1. " Identify the accidents analysed for plant licensing applications that are performed with the POWER TRAIN cave. Also identify all other codes used, if any, to provide input data to POWER TRAIN for these analyses in addition to the COMANCHE and PUMP codes, and describe all data transfer between codes."

Response

See Section 4.1.

Question 2. "Because of the limited core noding detail used in POWER-TRAIN, limiting DHCR, and limiting clad and fuel temperatures during accident transients can only be roughly estimated. Describe the manner by which these and other limiting parameters are determined for SAR analyses on the basis of POWER-TRAIN results."

Response -

See Subsection 4.1.

Question 3. "The course of accident transients can be appreciably influenced by various plant control systems in addition to the protective system. These

' controls are not described in the report, but some of their actions may be included in POWER-TRAIN analyses as indicated in some responses to questions.

As a result, it is not certain if their normal response is considered to be completely included in accident analyses using POWER-TRAIN. Provide a di:cussion of how the reactor, pressurizer, feedwater, steam generator and turbine controls resppase is considered in SAR analyses."

Response

See Subsections 4.3 and 4.4.

Questien 4. "The steam generator is described in generality with respect to the finite difference coitations used to compute the unit thermodynamics. The model detail used in accident analyses, the heat transfer regimes and correlations modeled, and the unit hydrodynamics are not presented. Provide descriptions for each of these aspects of the steam generator model to enable a more adequate understanding of the OTSG model ."

Response

See Section 2.16.

Question 5. "A sample application of the POWER-TRAIN code to an accident transient as submitted in an SAR is required. The computed results should be graphically presented for the primary system parameters, and all controls and' protective system action should be described or identified in a discussion.

cr on output graphics used to present results of the sample calculation."

Response

A POWER TRAIN application is discussed in Appendix A.

Question 6. " Sensitivity of results to uncertainties in primary controlling parameters in the plant design, such as flow rate, power level, system pressure, coolant volumes, reactivity coefficients, etc., should also be determined from analytical studies using the computer progran for off-design conditions."'

Response

See Subsection 4.5.

Question 7. " Verification studies using POWER-TRAIN to simulate plant or experimental system transients including protective and control action are also _ required to provide a degree of assurance that the computer program

- provides reasonably accurate predictions of accident transients for the SARs. Previous verification studies conducted by B6" with POWER TRAIN on plant startup transients, load swings, load rejections, etc., would be applicable for this purpose, and should be furnished in response to this infonnation request. The comparisons between experimental measurements and POWER TRAIN results presented in the response to Question 4 in the first round request for_ additional information, and in the response to Question 2 of the 1

second rr <.nd request are inadequate for this purpose as the comparisons concern .

l only minar perturbations to the steam generator portion of a plant simulation.

P0llER TRAlti verification should be based on comparisons with several plant parameters, such as, primary and secondary flow rates, temperature and pressure profiles along flow paths, pressurizer inventories, protective, and reactor, steam. generator, and pressurizer control systems response, secondary steam conditions, etc., to be considered adecuate.

Response

See Section 4.6. l 1

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