ML20246H951

Rev to Nusco 164, Large Break LOCA Analysis Sys Evaluation Model (NULAP5-LB)

ML20246H951
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	05/09/1989
From:	NORTHEAST UTILITIES SERVICE CO.
To:
Shared Package
ML20246H946	List: B13211, Forwards Rev to Nusco 164, Large Break LOCA Analysis Sys Evaluation Model (NULAP5-LB). Rev Corrects Description of Blowdown Heat Transfer Models in RELAP/MOD2 (Parent Code of NULAP5-LB) ML20246H951
References
NUSCO-164-ERR, NUDOCS 8905160241
Download: ML20246H951 (2)

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also extended into the subcooled boiling regime by setting the Reynolds number factor to one.

The post-CHF regime consists of models for transition film boiling, film

' boiling, and single-phase vapor convection. The transition film boiling modelin RELAP5/ MOD 2 was changed. A description of the change is contained in Section 4.4.3. The film boiling model has the form:

i:

Q,r = h ,, A.F,(T. - T,) / V (3-30)

Q ,, = h ,, A ,(1 - F,)(T, - T,) / V (3-31) where A, is the total wall heat transfer area and Ff is the fraction of wall surface contacted by the liquid. For single-phase vapor convective heat l ,

transfer, the wall is assumed to be dry and the heat transfer area between the wall and the liquid is negligible and the heat transfer from the wall to the vapor is given by the expression.

Q ,, = h A,(T. - T,) / V (3-32)

[

The Dittus-Boelter correlation is used for h wg.

In the condensation regime, heat transfer to the wall from liquid and vapor is dependent on the flow regime. Heat transfer from liquid to the wall is modeled by convection in the low void regime and heat transfer from 8905160241 890509 p DR ADOCK 05000213 PDC

t. 1.

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. 1 vapor to the wall is modeled by condensation in the high void regime. A void fraction weighting scheme is used to include the effects of condensate in the heat transfer from liquid to the wall for which the expression is J

Q ,, = [(1 - a.)h, _ m (T. - T,) + = ,h (T. - T,)] A. / V (3-33) where hcondis the condensation heat transfer coefficient. Heat transfer l from vapor to the wall is modeled by convection and expressed as Q , = [= ,h _ (T. - T,)] A. / V (3-34) 1 The correlations used to calculate wall. heat transfer are summarized in  !

Section 4.2 of Reference 3.10.2.

i 3.2.2 Interchase Mass Transfer The interface mass transfer is modeled according to the thermodynamic process, interphase heat transfer regime and flow regime. After the l thermodynamic process is decided, the flow regime map discussed in I Section 3.1 of Reference 3.10-1 is used to determine the phasic interfacial area and to select the interphase heat transfer correlation. 3 i

The mass transfer model is formulated so that the net interfacial mass l transfer rate is composed to two components which are the mass transfer l

l

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