ML20198P705
| ML20198P705 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 11/03/1997 |
| From: | Burzynski M TENNESSEE VALLEY AUTHORITY |
| To: | William Burton NRC |
| References | |
| NUDOCS 9711100086 | |
| Download: ML20198P705 (8) | |
Text
i t
l Tennessee Valley Authority 1101 Mwket Street, Chattanooq% Tennessee 37402 2001 s
November 3, 1997 Mr. William Burton U.S. Nuclear Regulatory Commission MAIL STOP: #0-11E4 Washington, D.C. 20555-0001
Dear Mr. Burton:
In the Matter of-
-)
Docket No. 50-327 Tennessee Valley Authority
)
REQUEST-FOR A TECHNICAL REVIEW OF A DRAFT INFORMATION NOTICE (IN) REGARDING INADVERTENT DRAINDOWN AT SEQUOYAH NUCLEAR PLANT (SON) UNIT 1' This is in response to the letter from Mr. Robert L. Dennig to Mr. Oliver D. Kingsley, Jr., dated October 21, 1997.
I have reviewed the draft IN enclosed with the subject letter and have the following comments.
With regard to the last paragraph on the first page (second paragraph under the " Description of Circumstances" heading),
the following comments apply:
The draindown was interritpted-for the diesel test at approximately 1:50 a.m. on March 24, 1997 (not 2:30 a.m.).
The phrase "although the actual pressurizer level continued to decrease" in the third sentence of the paragraph is incorrect and should be removed.
The draindown was ceased when the cold-Lalibrated pressurizer level instrumentation indicated 38 percent.
i O
A D O fl i ?
QJ t
9711100086 971103 PDR ADOCK 05000327 O
PDR IkE,0lE)E,$M!!
W MYW WW
l Mr. William Burton Page 2 November 3, 1997 The first part of the third sentence, "At approximately 38 percent pressurizer level, the level indication on the cold-calibrated instrument (had) stopped trendino down and held steady" should be moved to the next sentence and inserted after the phrase "when a member of the incoming operations crew recognized (that)."
This information is included in the detailed descript.'on of the sequence of events related to the pressurizer draindown in TVA's presentation material used at the June 27, 1997, predecisional enforcement conference (pages 21 through 25).
This information was included in NRC's Notice of Violation letter to TVA dated July 10, 1997, and the pertinent excerpt from the enforcement conference presentation is attached to this letter for completeness.
In addition, with regard to the last sentence of the second full paragraph on page 2, we believe that this statement is incorrect.
Plant procedures instruct operators to utilize all available level instrumentation.
The last paragraph under the " Description of Circumstances" heading pertaining to the SON event is also incorrect.
The paragraph begins, "A similar event occurred on Unit 1 in 1993.
The 1993 event was similar in that it involved a draindown of the reactor coolant system, but was. dissimilar in its root cause.
The sentence would be more accurately worded, "Another reactor coolant system draindown event occurred on Unit 1 in 1993 Thank you for the opportunity to provide feedback and to ensure accuracy of the information in the notice.
If yot. Pave questions regarding any of the comments, please telephone me at (423) 751-2508.
k,
!NarkJ.
Burzynski Manager Nuclear Licensing Enclosure
~
Sequoyaduc. ear Plant Event Evo_ution Sequence of Events (cont.)
t 2230 - Prejob Briefing Held Prior to Inventory Reduction Evolution 2257 - Stopped No. 2 RCP, Started RCS Depressurization
- 2302 RCS pressure <200 psig
- Started decreasing pressurizer level March 24.1997 0025 - Pressurizer Cold Calibration On Scale 0038 - Pressurizer Hot Cal On Scale
.First opportunity to notice indication was wrong 0150 - Stopped Pressurizer Inventory Reduction to Support Diesel Generator Surveillance Test (Cold Cal at 56%, Hot Cal At-25%)
- Hot cal protection channels must be >l7% to support surveillance 0630 - Cold Cal at 56%, Hot Cal at 2$%, RVLIS at 102%
a
e Sec uoyaa Nuc ear Plant Even1: svo u: ton Pressurizer Level Pressurizer Level (cicvation)
Expected Actual IIot Cal Cold Cal Ilot Cal Cold Cal 737' 2" 100 %
60 %
~99%
-94%
(Top of Ilot Cal) 721' 1" 25 %
22 %
~25%
~56%
4:- 5 f
~
719' 15 %
18 %
~15%
~51 %
716' 3" 4%
12 %
~4%
-40%
708' 2" Offscale - low Offscale -!ow Offscale -low
~ 38%
- A o er,IA (Mininium level reached) au d 'd 3
(pl uk W5 Cold cal indication will not decrease aller level decreased below lower tap e
O
]
9 2.2
e.
Sec uoyaa Nuc. ear Piant Event Evo ution
~
Sequence of Events (cont.)
At ~ 0710 - Pressurizer Inventory Reduction Was Resumed 0711 and 0712 - Two Alarms Came In (Letdown Isolation and Pressurizer Low Level)
' At ~ 0735 - Day Shift US and UO Assumed Shift and Noted Cold Cal at
-44% and Hot Cal at 0%
At ~ 0745 - Operator Noted That Cold Cal Stopped Decreasing (38%),
Inventory Reduction Was Terminated - Pressurizer Level ~ Two Feet Above Bottom ofPressurizer At ~ 0750 - Operators Started Increasing Charging At ~ 0815 - Pressurizer Hot Cal Came On Scale 4
'~
23 L________
Sequoyah Nuc_ ear Plant EventEvo ution
~
Sequence of Events (cont.)
0816 - Charging Low Flow Alarm Cleare.d 0825 - Two Log Entries Made Documenting Start of Pressurizer Inventory Reduction and When Problem Noted
- At ~ 0840.- Pressurizer Hot Cal Level 25%
At ~ 1500 - Cold Cal Level Instrument Reference Leg Backfilled, Hot Cal / Cold Cal Levels Were in Proper Agreement b-
x E
y i'
"9 w
m k1.f so
.CE a
l x
i Ak (A
\\~..
W
/
5 g
1 rei i Illi. 4
_<0 g-2 2R24 a
{e e We 7
8 8
~855 m
N
-Ed
~~
S Y-
- 5.8 8Lm etx2 Eliliiil gl gg-
~6E N
N C
<1
/
E l
7 Y 5 E
Ih5 0
ll A
4 o a R
8 3 3 g B
d e
see e
L WW Ub fb
=8 u..
W O R"@
W N
E=b E5;
- y 0
- g l
t a
-9 m
R$
~
mI mo W
Q:
Q.
W X
Q O
4
=--
~
m
Mr. William Burton Page 3 November 3, 1997 cc (Enclosure):
Regional Administrator U.S. Nuclear Regulatory Commission Region II
-61 Forsyth Street, SW, Suite 23T85 Atlanta, GA 30303-3415 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road
\\
Soddy Daisy, Tennessee 37379
,U.S.
Nuclear Reculatory Comm ion ATTN:
Document Control Desk Washington, D.C. 20555 i
. - _ _ -