ML20147G555

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Forwards Draft write-up from T/H Uncertainty Rept & Figure Attempting to Explain Quench Model Discussed Last Wk
ML20147G555
Person / Time
Site: 05200003
Issue date: 03/10/1997
From: Novendstern E
WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To: Fineman C, Landry R
IDAHO NATIONAL ENGINEERING & ENVIRONMENTAL LABORATORY, NRC
Shared Package
ML20147G451 List:
References
NUDOCS 9703280191
Download: ML20147G555 (10)
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C O V E R S H E E T FAX l To: Ralph Landry (NRC) Cliff Fineman (INEEL) g g i '

Subject:

Quench Model i, s Date: March 10,1997 , gpp [ g '3g Pages: Three, including this cover sheet. Ml- l Hrian A. Mc Intyre 1 COMMENTS: Ralph, 'l Attached is a draft write-up from the T/H Uncertainty report and a figure that attempts to explain the Quench Model we discussed last week. Please give a copy to Bill Huffman. Thanks. l l 5 

                    ,,, l From the desk of...

cc: B. McIntyre (NRC Informal File). L. Hochreiter, e.ris.nov.ndst.rn M. Young, R. Osterrieder, C. Thompson, Manager. Advamed and WER Plant Safety Analysis A. Gagnon, R. Fittante File 7.6 w.stingnous. PO Box 355 Pittsburgh. PA 15235 

  *                                                                                                    (412)374 4790 Fax: (412) 374-4011 Maren    .99'      . hT O NT . J 39' 9703280191 970321 PDR     ADOCK 05200003 E                               POR

1,) 0 h I l DRAFT l i DRAFT Quench Model item 7 above, " Core Node Heat Transfer Model", has been modified from the model described in Reference 5.2.3, Chapter 7. The model described in Reference 5.2.3 would determine the amount of stored energy in the fuel rod covered by the advancing I mixture level. The stored energy in the portion of the fuel rod which was covered by the mixture level during a time step was combined with the stored energy of that portion of the fuel rod which was below the mixture levelin the previous time step. This combining of the energies resulted in an increase in the temperature of the fuel rod below the mixture level. While this method conserved energy, it also resulted in an increase in heat transfer between the portion of the rod below the mixture level and the associated fluid node. The increased heat transfer below the mixture level increased , the void fraction, which swelled the mixture, forcing the mixture level higher. This I process of coupling the mixture level and the fuel rod temperature could feedback upon itself resulting in a rapid increase in the mixture level to a height above the active fuel, particularly at low pressure. When the mixture level rises above the top of the active fuel, the coupling between the mixture level and fuel temperature no longer exists and NOTRUMP's drift flux, bubble rise, and mixture level tracking models allow the mixture level to fall back to an appropriate level within the core. This tendency for the mixture level to spike to a height above the active fuel was corrected by requiring the energy removed from the fuel rod at the mixture interface to generate steam at the mixture interface, instead of increasing the fuel rod temperature below the mixture level. This approach more closely models the effects of fuel rod quenching and corrects the previous models tendency to swell the mixture and force the mixture level upwards in situations where an uncovered core was recovering.

Reference:

5.2.3 Meyer, P. E., "NOTRUMP, A Nodal Transient Small Break and General Network Code," WCAP-10079-P-A (Proprietary) and WCAP-10080-A (Non-Proprietary), August 1985. 

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                          .                                                                                      ..  .~

Quench Model AT T l Vapor T 3 No Quench Model e Q 

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l g I. Q increases fuel Z rod temperature e below mixture e level * 

                                                                                                 +

Vapor T>T 2 i Vapor T2 2. Q then raises Liquid .-- Ti<T<T o 2 mixture level + e e - s 

                                                 - s   _ _ _ _ _ _

Tl T Vapor T, Liquid Ti Liquid Ti Quench 1 Coolant Fuel Rod Model Ti Node Node _

l. Q boils off liquid at interface Liquid Ti
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I i FAX to DINO SCALETTI March 14,1997 l CC: Sharon or Dino. please make copies for: Tom Kenyon Ed Cummins Bob Vijuk l Brian McIntyre i 1 I OPEN ITEM #405 To meet the SECY-97-051 schedule of " Applicant Submits Final SSAR Revisions & Documentation" by 5/97. we beliese that NRC must acknowledge receipt of all Westinghouse i r submittals by May 30,1997. This is just 77 calendar days away. In my quest to make sure we l have provided NRC with everything needed to prepare an FSER. I have been providing background packages for open items that we believe are complete. Relevant documentation related to Open Item 

       #405 is attached. We provided a revision of the AP600 Security Design Vuh4erability Analysis on        l July 8,1996 (over 8 months agot We discussed this submittal with a reviewer in a telephone             I conversation over six weeks ago. NRC obviously had our submittal at than time. We then submitted
     > a revision of the analysis document on February 28,1997, but there were no changes affecting the vulnerability analysis itself. We believe that this information resolves the conc::ns of item #405 and that NRC has a responsibility to acknowledge its receipt. We requested a change in the NRC Status      ,

for this item with others in Chapter 13 on February 11,1997 (over a month ago). It seems a j reasonable request that NRC acknowledge receipt of the information. We request that NRC provide a l definitive action for Westinghouse or provide direction to change the status of this item. We I recommend " Action N" or " Closed" I will be sending this message by both fax and E-Mail. Thank you. Jim Winters 412-374-5290 P r l m' 

                                                                                                                                                                                                                                                                                       ~M AP600 Open Item Tracking System Database: Executive Sumntry                                                                                            Date: 3/14/97                                                                                         i Selection:      [ item nol between 405 And 405 Sorted by item 0 liem                  DSER Sectam/                        Title /DexTiptum                                           Resp                                                         (W)                                                                           NRC No        Branch      Quesrum           Type              Detail Staus                                               Engineer                                                     Samus                                                                        Samus       Letter No / Date 40%       NRR/TSGB    13 6              M TG Of                                                                       McIntyre B                                             Ckised                                                                           Acum W                    7/8N6 (October 25,1994 Secunty Meeting) Prmide a vulnerabelty analysis Vulnerabihty analysh mill h? subnutted with revised Securuy plan AlW NI Sxunt) I bign Vuhrs.dshly Analyus subemtled 7/hht, b) e O

N Page i Total Records: I _ _ _ _ _ _ _ _ - . _ _ . _ _ _ _ _ _ _ _ - _ _ _ - _ _ _ - _ . _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - -}}

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