ML20247P799
| ML20247P799 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde, Catawba, Harris, Saint Lucie, Vogtle, Waterford, South Texas, San Onofre, 05000000 |
| Issue date: | 04/04/1989 |
| From: | Miller H CONTROL COMPONENTS, INTERNATIONAL (SUBS. OF BABCOCK |
| To: | |
| Shared Package | |
| ML20247P804 | List: |
| References | |
| REF-PT21-89, REF-PT21-89-050-000 PT21-89-050-000, PT21-89-50, NUDOCS 8904070001 | |
| Download: ML20247P799 (2) | |
Text
-go y a wmut. cueumewmeneme wTrv q,
Control Components Inc.
An!MIvah,eeompany April 4, 1989 i
subject:
Atmospheric Dump Valves Potential Significant Deficiency Under 10CFR-21
\\
Daart We are hereby notifying you of a po:ential significant deficiency that We are not re-may be reportable under the requirements of 10CFR-21.
We porting this directly to the Nuclear Regulatory Commission (NRC).
at CCI do not have the systems exportise that would permit us to de-cide if this is a significant deficiency.
However, because of the NRC's interest and their pricr contact for.information regarding plants with a similar design, we have sent a copy to Rich Lobel of the Events Assessments group in Washingl:en D.C.
1 it's analysis of the Atmospheric Dump Valves for CCI has completed This analysis was prem; tad by the failure of the APSaPalo your site.
The Palo Verde valves are similar in design and Verde valves to open.
rely upon the same principle of operation.
The analysis has been aimed at cal ulating a worst case bonnet pres-sure after the pilot valve has been opened.
If the leakage by the piston ring is larger than the abi'.ity of the pilot plug to drain the If the pressure is bonnet, excessive pressure remains in the bonnet.the forces holding the u.ain too high, the actuator cannot overcome plug on the seat.
"2 Cur calculation indicates that the atmospheric dump valves at your site may fail to open.
The cause of the failure io speculative but
-J8 the result is a piston ring that fails to seal.
The high bonnet pres-That o o a.
sure resulting does not :permit the actuator to open the valve.
o8 is; the actuator force w:th the current air pressure supply available
$8 is not large enough to overcome the pressurs force holding the plug closed.
gg The condition can-kS As noted above, the cause of failure is not known.
be made to occur on demand ar.d in fact appears randomly.
our not speculation is that pipe scale and other dirt particles get into the gg Until the re-pisten ring cavity and prevent the ring from sealing.
cent Palo Verde testing in March 1989, we have been unable to verify mam that an excessive bonnet pressure txisted.
N OT* *s 0W&
TO ff/f
\\
22591 Annida Empesa O Panchc. Santa Mar;arita, Cahmia 92888
@ Tho N,pS e M Telephone;(714)8581877 O FAX (714)S58-1978 O Tbiex 685500
- .f
ma-s.,
n.v.
Pego a
~ The -resolution to this probica is to incroass the pilot valvo capac-
'ity.
This requires rework of the p:.ug to enlarge the pilot flow area and a new stem to seal the pilot valve when closed.
A second change is to use a two piece wedge style piston ring to as-sure a good seal.
This change is not as significant as increasing the l
pilot capacity but adds extra margin.
Plants for which there is a Egngarn that a random failure may occur and to whom this letter was sent are:
1)
Arizona Public Service - Dale Varda 1. 2 1 2 - t Valves Each
(
2)
Louisiana Power & Light - Wata N a 1 -2: Valves Each 3)
Duke Power
"=*'=** -1 2 - 4 Valves Each 4)
Southern California Edison - San Onofre 2_& 3 - 2 Valves Each Plants for which there is B2. Sam 13rr are:
1)
Florida Power & Light - & Lucie 2 - & Valves Each 2)
Houston Power & Light - Scuch Tavan Project 1_&
2_- 4 Valves Each 3)
Georgia Power vesshim 1 8 2 - 4 Valves Each 4)
Carolina Power & Light - Ehearon Harris 1 - 3 Valves Each This list of eight plants are the only ones that have designs similar 3
to the Palo Verde valves.
Other atmospheric dump valves exist at J
ether plants but their design is not the same as for the plants noted above.
The plants for which there is no coricorn have also been analyzed.
Our findings are that the valves have t.ufficient actuator force and plug An information pilot flow capacity to assure opening of the valves.
I copy of this letter has been sen-to these plants.
Please contact myself, Ron Adams, or Curtis Starud at CCI if you have any questions or for additional information.
Sincerely, CONTROL COMPCNENTS INC.
s H.
. Miller Vice President, Engineering
/jf cc CGsterud REAdams EJVillaiva RETopping l
CONTROL COVPONENTS INC.
_ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _