ML18347A684
| ML18347A684 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 03/23/1976 |
| From: | Bixel D Consumers Power Co |
| To: | Purple R Office of Nuclear Reactor Regulation |
| References | |
| XN-76-4 | |
| Download: ML18347A684 (9) | |
Text
consumers Power company*
General Offices: 21Q West Michigan Avenue, Jackson, Michigan 49201
- Area Code 517 788-0550 March 23, 1976 Director of Nuclear Reactor Regulation Att :
Mr Robert A. Purple, Chief Operating Reactor Branch No 1 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255, LICENSE DPR-20 PALISADES PLANT, CORRECTION TO XN-76-4 AND ANSWER TO NRC QUESTION ON POSTULATED BROKEN LOOP ACCUMULATOR FLOW BEHAVIOR FOR 1.0 DEG/PD CASE In a telephone conversation March 1, 1916, the NRC staff requested an ex!ilana~
tion for the sudden decrease in calculated. core flooding tank flow rate for the accumulator connected to the broken loop for the DEG/PD case with CD = 1.0 as shoim in Figure 2.48 of XN-76-4.
The cause of the Sl].dden decrease was deter-mined to be a pressurization of the break volume due to an inadvertent trip signal which opened the valve between the guillotine break volumes on a restart at 14. 2 seconds.
Additional calculations have been made to determine the effects of the valve trip on the LOCA ECCS analysis for the 1.0 DEG/PD case.
The RELAP4-EM blow-down case was restarted and run out to end-of-bypass.
End-of-bypass temper-atures were estimated from the blowdown results and the power distribution.
An additional TODEE2 heatup calculation was run conservatively using the time to refill and reflood rates from the initial RELAP4-EM/FLOOD calculation.
The use of previous refill and reflood results is conservative since the earlier end-of-bypass will result in higher injection rates and a longer duration of accumulator flow..
Results. of the blowdown calculation compared to the base case originally sub-mitted are attached and results from the TOODEE2 calculation are also given (Figures l through 6.). The calculated change from the base case is shown to
- be minor except for the broken loop accumulator flow rate which is calculated to go out the' break.anyway.
End-of-bypass was calculated at 27.77 seconds or 0.46 seconds earlier than the base case.
A PCT of 2065°F was calculated at 171.7 seconds with a local metal-water reaction of less than 10%.
Rupture was calculated at 45.7 seconds.
The hot spot temperature is estimated to be 2958
2 ll.3°F higher than the base case at end-of-bypass and 23°F higher at PCT.
Lo-cation of rupture was 7. 70 feet*, and PCT was 8. 20 from the bottom of the core.*
In conclusion, the questioned decrease in accumulator flow was caused by an unintentional opening of the valve between the breaks on restart for the DEG/PD CD = 1.0 case.
Additional calculations to determine the effect of this inadver-tent trip were performed, and the results are attached (Figures 1 through 6).
The trip had only a minor effect on the overall LOCA ECCS Analysis.
End-of-bypass was calculated 0. 46 seconds earlier and PCT was estimated to increase by 23°F.
The 1.0 DEG/PD case remains the limiting case and even with a 23°F increase in the DEG/PD CD = 1.0 case the guillotine break spectrum results are consistent and remain within the ECCS criteria.
- Locations given in Table 2.4 of XN-76-4 should.be corrected to read 8.20 feet in place of 8.32 and 7.70 instead of 7.78.
A revised table showing the cor-rections is attached.
Assistant Nuclear Licensing Administrator CC:
JGKeppler, USNRC
.1.1
[
- Peak Cladding Temperature, °F Peak Temperature Location, ft Local Zr/H2o Reaction (Max.),
Local Zr/H2o Location, ft Total Zr/H20 Hot Rod Burst Time, sec.
Hot Rod Burst Location, ft L___ __
TABLE 2.4 PALISADES LARGE BREAK RESULTS DEG/PD
_DEG/PD DEG/PD (CD = l. 0)
(CD = 0.8)
(CD = 0.6) 2042.
2036.
1966.
8.20 8.20 8.20
< 9%
< 8%
< 7%
7.70 7.70 7.70
<< l. 0%
<< l. 0%
<< l. 0%
47.8 45.9 49.9 7.70 7.70 7.70 r
r r
1.0 DES/PD 0.8 DES/PD 0.6 DES/PD
- a.
(9.818ft2)
(7.854ft2)
(5.89lft2)
~
2100.
8.20
< l 0%
7.70
- l. 0%
49.9 7.70 1994.
8.20
< 8%
7.70 1.0%
54 ~ l.*
7.70 1977.
.. 8.20
< 6~s 7.70
<< l. 0%
- 60. l 7.70
-+:::>
~x, n:z, 0
I
-s -.....J *
-s CJ'\\ I CD I
n-~:
c+
CD
. 0..
w N
N
-.....J.
O'\\
e e -
0 0
- ~*
0 0
.C) ru
.o
.0
~
- 'O
. - 0
- ~
- o jo
) QC 0
. 0
~
dJ PRLISRDES SLOWDOWN WREM/ENC e
16 2.0 2.4 TIME SEC FIGURE l PALISADES BROKEN LOOP ACCUMULATOR FLOW DEG/PD Co= 1.0 BASE CASE AND REANALYSIS e
e 2.9 3Z.
. 40
0 0
~
a:>
0...
CI8
(\\j
([
H (J)O (L~
- Lo wo J- ~
(f)
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-~
P~LIS~OES SLOWDOWN WREM/ENC
. Base Case
---~
a 16.
2.0 2.4 TIME SEC
---~-**---
FIGURE 2
- PALISADES SYSTEM PRESSURE DEG/PD Co= 1.0 BASE CASE AND REANALYSIS e
'2.8 3f.
36 4C
LJO w8 Ul ~
~
CD
_J I g I ~l_
0 3U)
~- I 0
- x::g
- a. 0 w-0::
CD -
0 Reanalysis
~
Base Case~----~~~ _
FIGURE 3 PALISADES TOTAL BREAK FLOW DEG/PD Co= 1.0 BASE CASE AND REANALYSIS 0
0 8.__~~~-"-~~~--'-~~~~~~~~-'-~~~~..L..~~----1.~~~~..L.~~~--1..~~~~L-~~~~
8 16 2.0 2.4 2.9 36 4-0 TIME SEC
0
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0 O*
0
.o
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.Ll
- no
'-.0 Eg
.!:JM
. _J
. I
- o 0
0 0
~
I 0
0 FIGURE 4
- PALISADES. DOWNCOMER FLOW DEG/PD.Co =-. 1.0 BASE CASE AND REANALYSIS
~~\\
2:
J
- Base Case
. *~:.
g "'-~~--..~~_,....---~~_,...~_,...-J-~_,.........-..,.,-1~--..__,..~....1-~-.---..--.J.--..--..-----.-....L-~~~-.J.._,...~_,..._,.....J.-_,...._,...._,..._,J 8
iS 2.0 2.4 2.8
- 32.
36 40 TIME SEC
'..Ll 0
- i 0
- J ~
z CI:
0::: 0 wo o_ ~
. 2.:
w t-0
- o 00 FIGURE 5 PALISADES BLOWDOWN HOT ASSEMBLY CLADDING TEMPERATURE
~~~,P~A~~ ;N~*~EANALYSIS
~
/*~
" *..c::- Base Case e
e 0
"--~~~--~~~__.~~~~---~~~__.~~--~---~~~
........ --~~~..._~~~-----~~~.__~~--~
~
16 2.0 2.4 2.9 36 40 1IME SEC
I I
c.
c:::
rr. r..ir-*-
i j
i c\\
c:: :
o I
~i l\\J' PRLISA]ES ]E6/P] C] := 1.0 H~T R!3]
3/S/76
'---------'--------L-
- l.
PCT N13]E
[N0]E 19 AT 8.20 FTJ
- 2.
F'AlLEJJ NBJl£ CN0J!E 17 RT 7.70 f'TJ
/
.~
---~*-----.....,;.__ --------------L--*---
FIGURE 6 PALISADES TOODEE2 HEATUP REANALYSIS DEG/PD c0 = 1.0
-***---.*-*"*-. _., __ --*--,__ 1
~
........... *.... \\
l
........_~........ --.... ----*-..
_.... --***-*- -.---... ~-*~-
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I
~
i
~
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i l
I e
e l
t --
- l 0
=~1 I
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