ML20235G721
| ML20235G721 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/24/1987 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8709300180 | |
| Download: ML20235G721 (6) | |
Text
- - - - - - - - - - - - - _ - _ - - - - _ _ _ _ _ _ _ _ - _ _.. _
TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374ol SN 157B Lookout Place SEP 241987 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
)
Docket Nos. 50-327 Tennessee Valley Authority
)
50-328 SEQUOYAH NUCLEAR PLANT (SQN) - AUXILIARY FEEDWATER (AFW) SYSTEM OPERABILITY DETERMINATION
References:
1.
Letter from TVA to NRC dated June 26, 1987, "Sequoyah Nuclear Plant (SQN) - NRC Request for Additional Information Regarding Auxiliary Feedwater (AFW) Flow and Pressure Requirements" 2.
Letter from J. A. Domer to B. Youngblood dated December 23, 1986, "Sequoyah Nuclear Plant - Technical Specification Change 71 - Auxiliary Feedwater Pump Pressure Drop Requirements" A meeting was held between TVA and NRC on August 19, 1987, concerning AFW operability. The objective of the meeting was to outline TVA plans to demonstrate operability of the 2A-A motor-driven AFW pump.
Detailed steps of the planned testing, calculations, and revision to the surveillance instruction are provided in enclosure 1.
The calculations used to determine the surveillance instruction acceptance criteria were provided in reference 1; a copy of the surveillance instruction was also included. shows how the measured values obtained during testing will be used in the calculation.
TVA believen the actions identified above provide an acceptable method to prove pump operability. TVA will submit a proposed change to the technical specifications 60 days after mode 3 testing, as originally proposed in reference 2.
r 87093001808%$27 4)390 A
An Equal Opportunity Employer
' U.S. Nuclear Regulatory Commission llffh[lhhf represents TVA's commitment to perform full flow testing for AFW every refueling outage.
If you have any questions, telephone R. W. Headors at'(615) 870-6649.
Very truly yours, TENNESSEE V LEY AUTHORITY
/
R. Gridley, D rector Nuclear Licensing and Regulatory Affairs Enclosures cc (Enclosures):
Mr. G. G. Zech, Assistant Director for Inspection Programs Office of Special Projects U.S. Nuclear Regulatory Commission 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. J. A. Zwolinski, Assistant Director for Projects Division of TVA Projects Office of Special Projects U.S. Nuclear Regulatory Commission 4350 East-West Highway EWW 322 Bethesda, Maryland 20814 i
Sequoyah Resident Inspector Sequoyah Nuclear Plant j
2600 Igou Ferry Road l
Soddy Daisy, Tennessee 37379 l
ENCLOSURE 1 The following information outlines postmaintenance testing necessary to demonstrate operability of the 2A-A motor-driven auxiliary feedwater (AFW) pump. The element of the 2A-A pump was replaced to increase flow margin.
The cavitating venturi was also optimized to reduce pressure losses. Figure 1 shows the old pump curve and system resistance curve along with the predicted new curves to be generated. Data collected by the postmaintenance testing will be used to calculate the surveillance instruction acceptance criteria.
Mode 5 testing will be performed to generate a new pump curve with the new element.
Both recirculation and full flow testing will be performed to generate a pump head curve.
TVA will revise plant surveillance instructions to require full flow testing for the AFW motor-driven pumps every refueling outage. These revised instructions will be in place by the unit 2 cycle 3 refueling outage for unit 2 and by the unit 1 nycle 4 refueling outage for unit 1.
The vendor's measured test value for pressure loss across the optimized cavitating venturi will be used to determine the new system resistance curve.
The calculation provided by reference 1, sheet 2a of enclosure 1, shows how the pressure loss across the venturi is determined.
The pressure loss across the installed optimized venturi is almost half of the pressure loss for the original venturi.
The required head to produce 465 gal / min (440 gal / min to the steam generators and 25 gal / min recirculation flow) will be calculated using the new system resistance (reference 1, enclosure 1, sheet 2b).
The actual pump head can be determined from the new pump curve at a flow rate of 465 gal / min.
Subtracting the required head from the actual head gives the allowable degradation (reference 1, enclosure 1, sheet 3a).
Assuming uniform pump degradation, inspection of the new curves will establish that adequate margin exists to deliver more than 440 gal / min to the steam generators at a pressure of 1,100 PSIA.
The surveillance instruction acceptaace criteria can be calculated once the allowable degradation is known.
Since the motor-driven AFW pumps are tested in the minimun recirculation mode, for the purpose of satisfying technical specification requirements, the available head is determined from the new pump curve at a flow rate of 25 gal / min.
Subtracting the allowable degradation and an allowance for instrument error from the available head gives the new surveillance instruction acceptance criteria.
The surveillance instruction (provided by reference 1, page 68 of enclosure 2) will be revised and performed before mode 3 to declare the pump operable.
Mode 3 testing will be performed to generate the actual system resistance curve and to confirm or revise, if necessary, the calculated values used to determine the required developed head.
This testing will finalize the pump margin and the surveillance instruction acceptance criteria value used to satisfy technical specification requirements.
TVA will submit a proposed change to the technical specifications 60 days after mode 3 testing, as originally proposed in reference 2.
. In summary, the AFW system will be determined operable before entering mode 4 by testing and calculations.
The actual margin available and specific surveillance instruction acceptance criteria will be finalized after entering mode 3.
{
o______._
tn o o ca o
_. en
$e INI0d 3)l0Ho a L
<w wm*
C<W W
U C3 w
QW-u-
- = 5d c<$
3*
no em e,v
~ -
weg 33
"$9 0210IC3tfd
~
.c WI$
NW
- > =.,
Zw-
- >. o
-m c.
O mo e,v, 031rinoivo Wo 4
ivnlov CQ g
<C CU 1
o
'j;;
- LL.
.c)
<::(
o-w E-O b
5-u 2
5 w
=
u m
w a.
- 5 c
5 m
zw c.
m E
wc 0
C S
m o-o x
W 2
(D E.
w w e
&m
>m o
c >o aO 2 2 o C Ju. J
_LL.
c.
13 a
c.
>=w Q
Co L.
wJC
<w u-OV3H dHnd "5
a-ow
-O pw g
O H<
ex
=w Wm
ENCLOSURE 2 l
TVA COMMITMENT 1
l TVA will revise plant surveillance instructions to require full flow testing 4
for the AFW motor-driven pumps every refueling outage.
These revised instructions will be in place by the unit 2 cycle 3 refueling outage for i
?
. unit 2 and by the unit I cycle 4 refueling outage for unit 1.
1 i
l