ML20153F385

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SER Accepting Util 870301 & 0407 Requests for Rev to Tech Specs,Modifying MSIV Actuation Control Sys,Per IEEE Std 279 & GDC 21
ML20153F385
Person / Time
Site: Nine Mile Point, 05000000
Issue date: 05/04/1987
From:
NRC
To:
Shared Package
ML20150F672 List:
References
FOIA-88-356 NUDOCS 8809070258
Download: ML20153F385 (5)
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Text

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1 LNCLOSURE I l

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NUCLE AR REGULATORY COMMISSION

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  • ...e SAFETY EVALUATION PEPORT TEOINICAt SPECIFICATION CHANGE REQUEST TO THE MSlv NIAGARA M0 HAWK POWER CORPORATION e Niht P!LE POINT UNIT ?

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DOCKET NO. 50 410 l

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1.0 INTRODUCTION

l by letters dated Morch 11, 1987 and April 7, 1987, Niagara Mohawk Power Corporation submitted a request for revision of the Technical Specifica-tions, Appendix A to Operating License NPF-54 for Nine Mile Point Unit 2 (hMP-2). The proposed changes would allow Niagara Mohawk to install new l Main Stean isolation Valves (MSlys) at NMP-2.

The MSIV's perfortn several functions such as Primary Containment isolation and Reactor Coolant pressure boundary. The installed MSIV's were originally 1

conceived to meet the Reactor Coolant pressure boundary function and '

improve upon the Primary Containment leas tightness performed previously by ball valves. Industry experience described in N'JREG-1169 indicates that MSIV leakage has been a concern. However, experience with the ball valves has shown that they have not functioned as well as anticipated.

Delamination of the tungsten carbide coating causes wearing between the seat and the ball which causes valve leakage. Packing leakage has also been a problem. Therefore, NMP-2 MSIV's were modified.

The modification includes cutting out the existing eight main steam isolation valves and replacing them with wye-pattern globe valves. The wye-pattern globe valves will meet all the same design criteria that the original design requires. For example, the design will neet safety related seismic, and environmental qualifications; and IEEE 279 requirements. The valves are being purchased from Gene <al Electric who normally supply the valves as part of the NSSS contract.

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. . tl i vat uAllt3 The Prutt'(.tinn Syltem slyndig that provide the trip 1 for the wyp. pattern MSIVs are the some signals utilized in the ball valve des 1gn. The power supplies are tne same non-Class lE 120VAC supplied by UPS3A (Trip System l A) and UPS3B (Trip System B). The design utilizes the same electrical protection assemblies (EPA), distribution panels and the same cables.

Tne f ail safe de-energize to operate lugic f unction, used for the bail Vol v rs , remains wi th the wye-pa ttern valves. This logic control circuitry utilizes relay logic (co11-to-contact) operation to assure that actuatior of a single emergency trip sensor (i.e. , one-out-of-two in trip system A or B) will not cause inadvertent closure of the MSIVs. This is consistent ith the original design basis of NMP-2 whereby the logic is set up as a one-out-of-two taken twice logic (i.e. , one-out-of-two in trip system A and B are required to close the MSIVs). For example, a tripped sensor (reactor low-low water level) provide open contacts to a logic function which Causes the sensor relay in the associoted trip channel to de-energize. The open contacts from the de-energized sensor relay are connected in logic functions which cause a trip relay to de-energize.

Output f rom the de-energized t.1p relays are cor. Joined in one-out-of-two taken tWiCe logic which generates closure signals for the main steam isolation valves.

I Each wye-pattern MSIV contains two electrically operated solenoid valves, d three way pilot solenoid valve with two coils ad a test solenoid valve.

The two pilot solenoid coils on a MSIV are fed f om different trip systems.

Sinc the two (2) trip pilot solenoid coils are sup) lied power from two (2) different trip systems and both trip systenis must de-energize to operate, a transfer and isolation scheme (ball valve) is not required on the wye-pattern valves. This change and tne standard General Electric l control scheme have reduced the number of field cables.

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The new wye-pattern globe valves will use a three pusition selection switch (close-out-test) and a pushbutton switch for each valve. These switches are located in the centrol room and are similar to the ball valve design. ,

Niagara Mohawk has requested that a revision be made to the NMP-2 Technical Spe'ification Tables 2.2.1-1, 3.6.1.2-1 and 3.6.3-1 to address the ins; llation of the new MSIVs. Table 2.2.1-1 has been changed to account l

for dif ferences in the physical configuration of the position indicating switches between the ball valves and the new wye-pattern globe valves.

Industry experience has indicated that the current Nominal Trip Setpoint ,

of less than or equal to 61 closed car.not be met with the mounting brackets on the globe valves. N1agara Mohawk has proposed that the MSIV -

Closure setpoint be less than or equal to 8% closed to allow margin for 1 i

field adjustment. A corresponding allowable value of less than or equal to 12% closed has also been proposed to account for drif t (allowable value). Table 3.6.1.2-1 and 3.6.3-1 have been changed to alter the valve l designations to provide consistent notation for the type of valve installed. )

Wye-pattern globe valves are used at the Perry Nuclear Power Plant in the same application and have been approved with setpoints identical to those requested for NMP-2. The staff has found that the change of setpoints is appropriate for wye-pattern globe MSIVs, changing of the valve designations is an administrative change.

3.0 CONCLUSION

Based on the above evaluation, the staff concludes that the iatest design modificatiurm made to the MSIVs did not change the actuation control system logic or power supplies and is consistent with the original design basis for NMP-7.. The M51V limit switch inputs to the Reactor Trip System logic remains unchanged from the ball valve design. However, the trip setpoint from the ball valve has been changed from 94% open to 92% cpen

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for the wye-pattern valve. We reviewed this 27 difference in setpoint and the supporting analysis and find the trip setpoint of 8% acceptable.

The staff concludes that the changes comply with the applicable regulatory acceptance criteria including the requirements of IEEE 279. We also conclude that the changes to Tables 2.2.1-1, 3.6.1.2-1 and 3.6.3-1 in the l technical specifications are acceptable.  ;

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ENCLOSURE 2 i

ICSB/ DBL SALP INPUT 1

PLANT: hine Mile Point Unit 2 LICEhSEE: Niagara Mohawk Puwer Corporation DOCKET N0: 50-410 LICENSEE STATUS: OR SER SUEJECT: TECHNICAL SPECIFICATION CHANGE PERF0PflANCE PARAMETERS:

s (1) Management involvement in Assuring Quality (2) Approach to Resolution of Technical issues From a Safety Standpoint (3) Response to NRC Initiatives (4) Staffing (including Management)

(5) Reporting and Analysis of Reportable Events (6) Training and Qualification Effectiveness (7) Any Other SALP Functional Area PERFORMANCE HARRATIVE DESCRIPTION OF CATEGORY /

PARAMETER APPLICANT / LICENSEE'S PERFORMANCE RATING 1 No basis for assessment N/A 2 Understanding of issue generally 2 apparent 3 Generally timely responses 2 4 thru 6 No basis for assessment N/A OVERALL APPLICANT / LICENSEE PERFORMAtiCE RATING 2 1

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