ML19322C301
| ML19322C301 | |
| Person / Time | |
|---|---|
| Site: | Crane, Davis Besse  |
| Issue date: | 02/14/1979 |
| From: | Rosalyn Jones BABCOCK & WILCOX CO. |
| To: | Cartin L BABCOCK & WILCOX CO. |
| References | |
| TASK-TF, TASK-TMR 86-2966, 86-2966-00, NUDOCS 8001160824 | |
| Download: ML19322C301 (2) | |
Text
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THE BASCOCK & tilLCOX COMPANY POWER GENERATION GROUP To j
L.R. CARTIN, PLANT INTEGRATION
)
From us us.s N.H. SHAH. ECCS ANALYSIS (2136)
Cust.
File No.
or Ref.
NSS-14 Davis-Besse 1 86-2965-0D Suoj.
Date RESPONSE TO TECO Ltiir.R 7
~15 February 14, 1979 lm...,....,..........,....W-,.
Reference:
C.R. Domeck to A.H. Lazar, "DB-1 Dual Level Setpoints on Steam Generators for Auxiliary Feedwater," TBW-505, dated January 2, 1979.
Please find attached ECCS's1 response to questions 1, 2, and 4 asked by TECO in their letter TBW-505, above reference.
Q/A:
Reviewed and approved the responses, it's conclusions and applicability to DB-1.
M Date A[/4!79 Sign
(
NHS/lc cc:
B.M. Dunn R.C. Jones E.A. Womack B.A. Karrasch E.W. Swanson H. A. Bailey 8001160 y y
86-2966-00 RESPONSE TO TECO L:i.:R TEW-505 Ouestion 1.
Compare the small break analytis (SAW-10075A, Revision 1) with natural circu-lation _ test results considering interim operation and ultimate operation after theldual levelisetpoint; change has been installed.
Please note that TECo had also requested B&W to provide this infonnation through TBW-503 (Item 5) dated December 4, 1978.
RESPONSE
The? natural circulation test: conducted at' DB-1 on November 3 & 4.' 1978, was re-
~
viewed for its applicability to a small break LOCA in an RC system. The test conditions of interest are as follows:
a.
Steady-state natural circulation, b.
Reactor power =4% of 2772 MWt.
RC pressure =2200 psia (within nomal range).
c.
d.
RC system full with sub' cooled liquid (except pressurizer).
SG secondary pressure =900 psia (using turbine byoass).
e.
- f. ? Secondary set level = variable'(35" to 13 foot of cold liquid ~on startup.
1 and operate range).
g.
Vent valves - closed.
The results showed that the natural circulation flow rates varied with the level from s 4.5% to S 5% of normal flow obtained by 4 pumos at full power.
Also, for set levels above 8 foot, the steam generator heat transfer per-formance was adecuate to cool the RC primary liquid aooroximately to the secondary saturation temperature.
For the 35" level control, the RC cold leg temperature remained about 14F higher than the secondary saturation tem-perature.
During the small break transient (topical report BAW-10075A, Rev.1), an RC pumo coastdown occurs, when pump trips, due to the assumed loss of off-site power.
Thus, the loop circulation during the initial stages of the transient is controlled by the pump coastdown and the system inertia and flows are in excess of natural circulation conditions.
During the pumo coastdown, or soon thereafter, sufficient steam will be created in the upper U-beqd of the hot legs due to flashing in the hot legs and steam generation due to the decay heat, which will retard or break the continuity of the loop flow, i.e., natural circulation. The system flows thereafter are mainly governed by the loop drainage through the break and the opening of the vent valves.
Thus, during a.small break, the natural circulation, if it existed, would dominate for a limited period only.
The ESFAS signal wnich occurs during tne cumo coastdcwn period will result in the auxiliary feedwater system controllec to a hign level (10 foot level).
As shown by the test, both the high and low levels will provide an efficient heat transfer mecia for decay l
l 4
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