TXX-6557, Interim Deficiency Rept CP-87-19 Re Ambient Temp Effects on Plant MSIV Actuators.Initially Reported on 870611.Mechanical Spec MS-76 Re Temp Transient,Valve Mods & Equipment Qualifications Under Evaluation.Next Rept by 870918
| ML20235J484 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 07/10/1987 |
| From: | Counsil W, Keeley G TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-87-19, TXX-6557, NUDOCS 8707150589 | |
| Download: ML20235J484 (2) | |
Text
_ _ _ __ __ _ _ _
?,
c.
M Log # TXX-6557 F9 File # 10110 910.3 l
r r
Ref # 10CFR50.55(e) nlELECTRIC WlHiam G. Counsil.
Eucutive Vke Preskknt U. S. Nuclear Regulatory Commission ATTN:. Document Control Desk Washington, D.C.
20555
-1
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 AMBIENT TEMPERATURE EFFECTS ON MSIV ACTUATORS SDAR: CP-87-19 (INTERIM REPORT)
\\
Gentlemen:
On June 11, 1987, we verbally notified your Mr. Bob Warnick of a deficiency involving the ambient temperature effects on MSIV actuators.
This is an interim report of a potentially reportable item under the provisions of 10CFR50.55(e).
The manufacturer (Rockwell International) has advised TU Electric that tho thermal compensating accumulator on the valve actuator attached to the Main Steam Isolation Valves (MSIV) may not function in accordance with the CPSES procurement specification. The specification requires the actuator to ^
function correctly through an ambient temperature swing of 800F.
Test results, recently acquired by Rockwell, indicate the greatest possible ambient swing, which will not impair the function of the actuator, is 340F. At present, any increase above the 340F ambient temperature swing could result in excessively high hydraulic pressure to the unit which could damage components in the actuator or possibly inhibit the main pump hydraulic solenoid valves from shifting.
In the latter case, the actuator would not perform the required safety functions.
These adverse pressures should occur only during increasing thermal transients of the ambient environment while the actuator is in the open position.
This could typically occur during a plant heatup with the valve and actuator open.
This condition is applicable to both Unit 1 and 2 and affects the main steam isolation valves and associated A-180 actuator and accumulators.
Specific tag L
numbers for the affected valve are as follows:
1-HV-2333A, 1-HV-2334A, 1-HV-2335A, 1-HV-2336A 2-HV-2333A, 2-HV-2334A, 1-HV-2335A, 2-HV-2336A B707150589 e70710 r
PDR ADOCK 05000445
'i S
PDR gC,c91 il0 a u ou sa,cca an u. m n m oi
TXX-6557 i
July 10, 1987 Page 2 of 2 Our evaluation includes the following:
1)
The Mechanical Specification (MS-76) currently specifies an 800F ambient temperature (40-1200F) increase. This requirement will be reviewed to determine if the temperature increase can be limited to 340F.
2)
The allowable temperature increase can be raised to 550F by I
increasing the nitrogen gas precharge pressure to 90% of the hydraulic operating pressure of 2650 psi instead of the' current precharge of 1325 psi. The system review will assess if the temperature transient can be limited to a rise of 550F.
3)
If the review indicates that the temperature gradient cannot be limited to one of the lower values suggested above, the A-180 actuators will be modified so that the original specification requirement of 800F can be achieved.
The modification may consist of the installation of a pressure relief valve in the hydraulic system for each valve.
4)
Equipment environmental and seismic qualifications.
The results of the above evaluation will be used to assess the significance of this issue.
Our next report on this issue will be submitted no later than September 18, 1987.
Very truly yours, h4 W. G. Counsil
/
By:
_ s.,
G. S. Keeley W
Manager, Nuclear Li ynsing MCP/mgt c - R. D. Martin, Region IV Resident Inspectors, CPSES (3)
_