ML20082E876
| ML20082E876 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 11/17/1983 |
| From: | Bob Nelson ILLINOIS POWER CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0853, RTR-NUREG-853 U-0678, U-678, NUDOCS 8311280355 | |
| Download: ML20082E876 (3) | |
Text
-m,
U- 0678 O
L ILLINDIS POWER COMPANY
)_
500 SOUTH 27TH STREET, DECATUR, ILLINOIS 62525 Docket No. 50-461 November 17, 1983 Director of Nuclear Reactor Regulation Attention:
Mr.~A. Schwencer, Chief Licensing Branch No. 2 Division.of Licensing U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Subject:
. Clinton Power Station Unit 1 SER Confirmatory Issue No. 69 (NUREG-0853 )
Containment 24"/36" Vent & Purge Valve Operability
Dear Mr. Schwencer:
Illinois. Power Company (IP) Letter U-0571, from G. E. Wuller to C. O. Thomas, dated October 22,-1982 provided your staff with a detailed analysis of all.the Clinton Power Station (CPS)
Containment-Vent and Purge (V&P) Valves supplied by POSI-SEAL Inc.
This analysis, performed by POSI-SEAL, determined the loads (valve stresses) experienced by these valves under postulated worst-case combined LOCA and seismic conditions.
In the NRC letter, from A.
Schwencer to G. E. Wuller, dated July 20, 1983, the Staff provided IP with the results of its review of the POSI-SEAL analysis.
The basic NRC concern is the methodology used to convert lift and drag torque coefficients obtained from' water tests into the corresponding coefficiente applied to these valves for air.
Based upon this concern, we have concluded that the most suitable solution for CPS is to limit the 24" and 36" valve opening angles to 50' through the use of mechanical-stops on the valve actuators.
The attached diagram shows a proposed mechanical stop that limits the valve actuator travel.
With these valves limited to 50' open, a maximum of 19,000'cfm flow is attainable.
IP believes that this limited purge flow'during normal plant operating modes'will not present operational restrictions since the CPS high-volume purge system
.is restricted in use to no more than 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> / year while in Modes 1, 2, or 3.
However, during plant operating Modes 4 and 5
-(cold shutdown and refueling) nearly continuous containment access may be necessary for plant maintenance activities.
The
.NRC Staff has agreed to allow unlimited use of these valves during Modes 4 and 5 such that proper containment ventilation conditions can be established for plant operating / maintenance
. personnel.
g v4F/
hDkkbo O
00 E
~,
A. Schwencer U-0678 Page #2 L30-8 3 (ll-17 ) -L IP proposes to utilize these. mechanical stops such that they would be in place (valves limited to 50* open) during Operational
~ Modes 1, 2, and 3 and could be removed during Modes 4 and 5 if increased purge flow (30,000 cfm with valves full open) is required during maintenance activities.
The NRC letter of July b
20, 1983 states that limiting the 24" and 36" valve opening angles to 50 is an acceptable resolution of this issue.
Functional operability of these mechanical stops will be assured as part of the ongoing CPS plant operational maintenance and inspection program.
Finally, the body-to-bracket bolt material for the 36" valves will be changed to the higher stress allowable material (A354 GR BD) as recommended by POSI-SEAL in their report to the NRC submitted on October 22, 1982.
In addition, the orientation of all valves to the NRC has been checked to ensure they are installed as recommended in this report.
All CPS containment vent and purge POSI-SEAL valves are presently installed or will be oriented to conform to preferred orientation as recommended.
It is IP's position that these commitments are adequate to ensure that the NRC vent and purge valve operability requirements are met at CPS.
Please inform me if you have any additional concerns regarding this matter.
Sinc y yours,
' - '!\\_
elson Director - Nuclear Licensing and Configuration Nuclear Station Engineering TLR/lgm cc:
G. A. Harrison, NRC Clinton Licensing Project Manager NRC Resident Office L. C. Ruth, Containment Systems Branch D. D. Reiff, Equipment Qualification Branch
[
Illinois Department of Nuclear Safety l
s
=
r
- e
?
e.
.o Attachment to letter
~
U-0678 dated November 17, 1983 CPS-24"/36" Containment Vent and Purge Valves MATRYX-ACTUATOR Mechanical Stop
~
for Restricting Valve Opening to 50*
i
._ -Piston Capscrew 1i
_f 4 --->
g 0
/
I j -.
-r-Mechanical Stop I
Endplate.
ll Actuator Hub Piston Cartridge 5
i j
. - - - -.