ML19347C958
| ML19347C958 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/04/1981 |
| From: | Morisi A BOSTON EDISON CO. |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| 81-46, NUDOCS 8103100386 | |
| Download: ML19347C958 (5) | |
Text
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Mr. Thomas A. Ippolito, Chief
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Operating Reactors Branch #2 Division of Licensing
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,D"'*r Office of Nuclear Reactor Regulation p
c U.S. Nuclear Regulatory Comission
- 4 Washington D.C.
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bg-License No. OPR-35 Cocket No. 50-293
Dear Mr. Ippolito:
Attached for your review please find additional infomation regarding containment vent and purge valve operability as requested in your letter dated December 10, 1980.
If as a result of your review, you should require any additional in-formation, please do not hesitate to contact us.
Very truly yours,
Attachment:
Additional Information on Containment Vent and Purge Valve Mechanical Operability ldM'
-8103100386 j
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ADDITIONAL INFORftATION ON CONTAINMENT VENT AND PURGE VALVE MECHANICAL OPERABILITY 1.
Provide the following information for the 20.0 inch butterflies, e Rockwell valve's part number e Bettis operator's part number e Solenoid valve's manufacturer and part number
Response
e Rockwell valve part number #227176 for Inner Valves & #224361 for Outer Valve.
e Bettis operator part number MODEL 722-A-SR e Solenoids are ASCO MODEL NP 8320A184E 2.
What is the source of the " commercially accepted data for butterflies" used for the 20.0 inch valve analysis? What was the value of the dynamic torque coefficient (C ) used? Were installation effects accounted for T
in the detennination of dynamic torque developed? Dynamic torque is known to be affected by valve relation to upstream elbow, shaft orien-tation relative to elbows, disc closure direction relative to upstream elbows.
Response
Fisher Controls,McNally Valve and Dover Corporation technical B rochures were used in the calculation of dynamic torque. The value of CT used was approximately 400 in the equation for a 20" valve, where Torque = CT AP LB-inches and the valve is 450 open. A P is the effective pressure drop across the valve causing unbalanced torque on the disc.
Installations were judged to have an insignificant effect on the dynamic torques since the nearest elbow on the drywell lines is 5 pipe diameters away from the valve.
3.
What were identified as the critical parts in these 20.0 inch valves (shaft, disc to shaft pins, other)? What were the stresses calculated?
Do they include simultaneous seismic loading? What are the design allow-able stresses? What code or standards are the valves designed to?
Response
We identified shaft, disc to shaft pins and shaft to operator key as the critical components. When dynamic and pressure loads are considered, shaft shear stress is 6250 psi; pin shear stress, 4884 psi; and keyway bearing stress, 8700 psi, e
., Stresses due to seismic loadings were judged to be small and were not included.
We do not have available design calculations on the valve because the manufacturer is no longer in the butterfly valve business. However, since shaft and pins are 316 ss we consider design allowables should be taken to be18,700 psi in tensior, for normal operation.
The valves are designed to B16.5 with material impact tests for the valves closest to containment.
4 Are any of the 20.0 inch valves inside containment? For those valve assemblies (with air operators) inside containment, has the containment pressure rise (backpressure) been considered as to its affect on torque margin available (to close and seat the valve) from the actuator? During the closure period, air must be vented from the actuators opening side through the solenoid valve into this backpressure.
Discuss the installed actuator bleed configuration and provide basis for not considering this backpressure affect a problem on torque margin. Valve assembly using 4 way solenoid valve should especially be reviewed.
Response
None of the valves are inside containment.
5.
Do the 20.0 inch valves use accumulators as the fail-safe feature? Where air operated valve assemblies use accumulators as the fail-safe feature, describe the accumulator air system configuration and its operation.
Provide necessary information to show the adequacy of the accumulator to stroke the valve i.e. sizing and operation starting from lower limits of initial ~ air pressure charge. Discuss active electrical components in the accumulator system and the basis used to detennine their qualification for the environmental conditions experienced. Describe the extent to which the accunulator system is seismically designed.
Response
The valves all use stored spring energy to close and do not use accumulators as the fail-safe feature.
6.
Describe the modification made to the. valve assembly to limit the opening angle. With this modification, is there sufficient torque margin avail-able-from the operator to overcome any dynamic torques developed that tend to oppose valve closure, starting from the valve's initial open position?
Is there sufficient torque margin available from the operator to seat the valve against seating and bearing torques developed?
Response
Longer stops were put on the spring cylinder side of the Bettis operator 0
to. prevent the' valve from opening more than 45.
- Since the disc is syninetrically located on the stem, dynamic torque will
. tend to aid valve closure.
The torque margin available from the operator during the 450 to closure part of the stroke has not been altered by the addition of the stop and is sufficient to close the valve.
7.
Describe the tests and/or analysis perfomed to establish the qualifi-cation of the valve to perfom its intended function under the environ-mental conditions exposed to during and after the DBA following its long tem exposure to the nomal plant environment.
What basis is used to establish the qualification of the valve, operators, solenoid valves? How was the valve assembly (valve and operator) seismic-ally qualified (test / analysis)?
Where testing was accomplished, describe the type tests performed, con-ditions used etc. Tests (where applicable) such as flow tests, aging simulation (themal, radiation, wear, vibration endurance, seismic), LOCA environment (radiation, steam, chemicals) should be pointed out.
Where analysis was used, provide the rationale used to reach the decision that analysis could be used in lieu of testing.
Discuss conditions, assumptions, other test data, handbook data, and classical problems as they may apply.
Response
The valve ability to perfom its functions is assured by selection of appropriate materials per the original design specification and periodic testing to monitor deterioration. Valves and components were specified to withstand seismic accelerations of 159 horizontal 05g vertical for design basis earthquake and maximum accelerators of 269 horizontal and 109 vertical.
Solenoid valves qualification infomation was supplied via IE Bulletin 79-01B response dated 10-29-80, BEco letter #80-272.
8.
Have the preventive maintenance instuctions (part replacement, lubrication, periodic cycling, etc.) established by the manufacturer been reviewed, and are they being followed? Consideration should especially be given to elastomeric components in valve body, operators, solenoids, where this hardware is installed inside containment.
Response
These valves are not installed in containment; however, their perfomance is evaluated under Appendix J leak rate testing and the periodic valve timing required by Technical Specifications.
-~
9.
Describe the Inservice Test Program ( ASME,Section XI) presently being conducted or planned for the subject valves.
Response
Our test program is in accordance with Appendix J-1 and Section XI INV 34-20. We seat leak test every valve during each refueling outage and at less than 2 year intervals.
Our operational checks are also performed during outages. The position of the valves before and after each test is recorded.
- 10. Provide an assessment of the structural capability of any ducting or piping in the purge system which is upstream or downstream of the valves and is exposed to the flow conditions associated with the LOCA and the seismic event. The staff is particularly interested in the effects that loose debris from the pipe or duct system may have on the closure capabil-ity of these valves.
Response
The thinnest oice uostream of the valves has a 3/8" wall which is adequate to withstand LOCA pressures. The Drywell penetrations were covered with jet and debris deflectors during our 1980 outage. Debris generation is being addressed in the Mark I program for torus penetrations.
The duct downstream of the valves and its protection is still being analyzed.
In addition, as recuested by Mark Williams of your Staff, we have provided the following information:
o The two valves with no installed mechanical stops are located l
outside +he nitrogen tie in lines and are not opened during power operation nor during startup (when purging of the drywell with nitrogen occurs); therefore, the valves are never exposed to the possibility of a LOCA while open.
o The A" valve in the nitrogen tie in line is excluded from the concerns of the original bulletin as well as the 2" bypasses around the butterfly valves ard other bypass valves because they are either globe or gate valves and are not subject to dynamic torque as are butterfly valves.
o Pilgrim Station Operations procedure No. 2.2.70 " Primary Con-tainment Atmospheric Control System" has been revised t' incor-porate amninistrative controls which will limit the time the 20" vent and purge valves are open to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> /yr. during power operation.
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