ML20066G775
| ML20066G775 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 11/09/1982 |
| From: | Conn W WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| REF-PT21-82-736-000 BRGO-RO-82-012, BRGO-RO-82-12, PT21-82-736, PT21-82-736-000, NUDOCS 8211230047 | |
| Download: ML20066G775 (4) | |
Text
U g
4 og e
"te g Burns and Roe,Inc.
601 Wi!!iams Blvd. m Richland, Washington 99352 m Tel. (509) 943-8200 b [// j,
Subject:
Work Order 3900-4000
// P4p'-
Washington Public Power Supply System WNP-2 10CFR21 Reportable Condition #82-10 Main Steam Isolation Valve-Leakage Control System Responds to:
NA November 9, 1982 BRGO-RO-82-012 Response Required:
NA U.S. Nuclear Regulatory Commission Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94956 Attention:
Mr. R.H. Engelken Gentlemen:
This letter is to inform you of a condition we have deemed to be reportable under the guidelines set forth in 10CFR21.
WNP-2 design incorporates a Leakage Control System (LCS) past the Main Steam Isolation Valves (MSIV). The purpose of the system is to direct fission products, which may leak past the MSIV's, to the Standby Gas Treatment System (SGTS).
It has been discovered that a path of in-leakage may exist post-LOCA which could negate the ability of the MSIV-LCS to perform its safety function. This path exists because a valve required to isolate post-LOCA is not powered from a crital bus. This could result in off-site doses which are a substantial fraction of 10CFR100 values.
Complete details are contained in the attached evaluation.
If you have any additional questions, please contact A.T. Luksic at (509) 943-8243.
Very truly yours, WGC:ATL:lvs Attachment W.G. Conn cc:
B.A. Holmberg, SS w/a Senior Group Supervisor J.G. Tellefson, SS w/a R.T. Johnson, SS w/a L.C. Floyd, SS w/a R.M. Nelson, SS w/a E. LeBlanc, BPC w/a s21123OO47 821109 j
PDR ADOCK 05000397 S
PDR 7 8-Ik
Attechment Main Steam Isolation Valve - Leakage Control System (MSIV-LCS)
(82-10)
Description of Deficiency WNP-2 design incorporates a leakage control system past the MSIV's in order to minimize the release of fission products if the MSIV's were to seat poorly. Suction would normally be taken off the piping downstream of the outboard MSIV, and discharged into the Standby Gas Treatment System (SGTS).
It has been discovered that a valve, MS-V-146, on one of the branch pipes is not powered from a critical bus.
Post-LOCA, one could not assume it would close, nor could one assume the piping past the valve, ANSI B.31.1, would remain intact.
The fans associated with each MSLC system are designed for 50 cfm flow at 20" of water. Of this flowrate, about 10% is leakage from the main steam lines, the balance is diluent air.
This amount of steam does not affect the Standby Gas Treatment System Operation.
However, this flowrate is too small to create a face velocity of sufficient magnitude to assure in-leakage of Turbine Building at-mosphere into a 24" pipe. Thus, the fan of the outboard MSLC will not create sufficient suction pressure and line velocities to as-sure that backflow of fission products past this open valve to the atmosphere and hence to the site boundary does not occur.
Date and Method of Discovery The deficiency was discovered during a Human Factors Engineering Review and documented on September 10, 1982.
Analysis of Safety Implication As stated above, the function of the MSLC system is to prevent po-tential leakage of containment atmosphere through closed main steam isolation valves from reaching the site boundary without filtration after a LOCA.
It is postulated that after a DBE, the non-seismic Class I steam piping will no longer be intact. An open path to the Turbine Building atmosphere will be created.
3 This leakage is postulated to occur at a rate of 11.5 ft /hr per steam line due to poor seating of the MSIV's.
The fission products in this leakage stream, were they to reach the site boundary with-out filtration, could result in off-site doses which are a sub-stantial fraction of 10CFR100 valves.
Corrective Action Valve MS-V-146 will be powered from a critical bus to assure that the MSIV-LCS can perform it's intended function when required.
Applicability to Other Nuclear Projects None.
This situation is unique to WNP-2.
"S8
- Nuc' Niect No. 2 BURNS AND ROE, INC.
RECORD OF TELEPHONE CONVERSATION
//-
-B 2
/.* 3 O
( LYES y;,,
To de confirmed
- Dat,
("lNC FROM TO I
h g h Dps-
]
t>M$/CJ n,m, Name
'bUPAfs M kOE Cornpany or Dept. _MMO k6f./ OM Company or Dept.
SU8KCT(S) DISCUSSED EOM T/A/6 E
AMI bA/Al TEAM SSol ATIOKJ VA W - lEAkA gf~ fo A> Trot SYSTEM REMARKS SAo f LL) 0 S S/h 6M14 f Init ila6 tot latu enuoOl2er we lAur clerinrc ) m on Yillr o
i oa1lrx
/O CfP 2/. $ an us /> km <emt kAir l </rYMk O{ f$L MnllrArt rl Adtn'rfr/ Ara >, tlat
/ ossa /,/
n kt W-At$ct b bu //-/0-92.
bt stat the no a
.fT/ b, L
/f
/ /w
n'
~
v.
C kh W
o gc, s
5 t
eon." "' ER, Kwnwd W6. C~
CW.kasM
'B. A.H4 boy E.La B Le-BPC, J* 7, Vcuk6se L
4cym R 7.Vx w T.G. Trflek 6ik 6/es-2 f hjhf A. As. h'ucteR A.J. Laqrans~ A.7LJsh. f*fk't~
S l
A. L CYGCLHA
H.R.Tald/
R.H.Al 7to~ c A7 luksicl]$
t
,,,,_o,
r Log Sheet No. [
PART 21 REPORT LOG SHEET Subject of Report - M $ n f b w [ La d 8 h
1.
a 7
2.
te Verbal Notification Received -
[E 2-Received B2 -J'L 7/hM Date Infonnation Placed in Daily Report - J(/f 92-3.
/
4.
Name and Address of Person Providing Verbal Notification a) Name _ [ M e d [ g f g b) Company and Address -
h[M R&/ /Uf
/
c) Telephone No. - fo9 -9'/-3-9? /G 5.
Description of Problem
<[
N
_ta-</-/v /& W fl7b4fAL det /
Y O
M m __
5.s />s&
W M
%{ Cd M
~ w ow L ff A d.
y' l
6.
Nuclear Facilities Affected -
dd///M 2-h l
?
7.
Date 5-day Written Report Due - // /B P'~1 /
Date Received -
J
/
8.
Mail Written Report to HQ's and Other Affected Regions a) Date Mailed to HQ's (Bill Mills) -
b) Date Mailed to Other Regions -
Regions Mailed To_ -
9.
Give Written Report to Each Region V Affected Principal Inspector a) Date Given to Principal Inspector (s) -
b) Name(s) of Inspectors Given To -
- 10. Additional Comments -
O l
a