ML19345F724
| ML19345F724 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 01/21/1981 |
| From: | Parker W DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-80-23, NUDOCS 8102190122 | |
| Download: ML19345F724 (3) | |
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DUKE POWER COMPANY Powen Bt: Lotxo we Socin Cat:ncu Sruzzr. CauntorTE. N. C. 2e24a t'
January 21, 1981
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- a2 Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission Recion II I
Marietta Street, Suite 3100
-.anta, Georgia 30303
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Docket Nos.60-369, 50-3_
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Dear Mr. O'Reilly:
Please find attached McGuire Nuclear Station's response to IE Bulletin 80-23.
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Eu nt: L uc William O. Parker, Jri j RWO:scs Attachment cc:
Director Division of Reactor Operations Inspection Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
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DUKE POWER COMPANY MCGUIRE NUCLEAR STATION RESPONSE TO IE BULLETIN 80-23 By January 9,1981 the coils of all Valcor solenoid valves with part numbers V70900-21-1 or V70900-21-3 used on McGuire Unit 1 or shared between McGuire units were replaced with coils of an improved potted construction.
The coils for valves in unit 2 will be replaced at a later date.
Valves with the new coils are qualified for their intended lE service (i.e., normally energized; deenergized on receipt of a safety signal) by similarity and testing based on Valcor qualification test reports QR52600-515 Rev B, OR70900-21-1 Rev. A, and interim test report MR70905-21-3-1.
Valcor has submitted addendum 1 to their interim test report which provides the latest information available from on-going aging tests on the new design coils and states the coil's aualified life based on the testing completed as of the report date (1/9/81).
Valcor solenoid valves V70900-21-1 and V70900-21-3 equipped with the new potted coils are considered qualified for their intended lE service based on the following:
l.
The solenoid valves with the coils of the original design were qualified by similarity by Valcor qualification test reports QR52600-515 Rev. B and OR70900-21-1 Rev. A for a normally deenergized mode of operation and cycling operation a LOCA.
2.
The problems experience with normally energized operation were a result of a problem with the coil design only, and does not affect the thermal, cyclic, radiation, seismic or LOCA qualification of the solenoid valve (less coil).
3.
The coil has been redesigned for normally energized operation by (1) a change in materials of construction and (2) the addition of a potting compound between the solenoid coil and the shell enclosure.
cti "
(a) Materials of Construction - All materials utilized in the const5"C of tge new coils are U.L. rated for continuous operation at 220 l
(428 F) with the exception of a tape used to cover both the solder joigts and the complete coil winding.
The tape is classified as a o
180 C (356 F) tape and is a U.L. recognized component.
(b) Potting Compognd - The potting material used is rated by Emerson and Cuming at 350 F.
4.
The significance of the above design improvements are as follows:
(a) The utilization of the higher temperature rated materials means that the new coils will be suitable for normally energized operation at normal and accident temperatures.
The addition of the potting material allows the coil to dissipate more heat, and in normal operation, the coils will operate at a reduced temperature which extends the operating life.
This has been proven by the additional testing described in interim test report MR70905-21-3-1.
(b)
Valcor has subjected six (6) prototype potted solenoid coils to on-going aging tests.
The coils are energjzed sugh that the coil wire is at its rated material temperature of 220 C (428 F).
Testing at this temperature is an accelerated aging.
To date, no failures have been experienced and
e the coils are qualffied for normally energized operation in an ambient temperature of 140 F and nominal voltaae for 4.07 years.
The McGuire0 specification states a normal ambient temperature of 120 F, so the 20 difference betwee.n the test ambient and the specified ambient more than satisfies the 15" margin recommended by IEEE-323 (1974) paragraph 6.3.1.5.
(c)
Based on test gata obtaircad from valves at an gouilibrium ambient temp-erature of 140 F, the coil temperagure rose 91 F over ambient after 15 minutes of energization.
Using 91 F as tge coil temperature rise during aLOCA,thecofltemperaturewouldbe433F.
This is based on a constant g
ambient of 327 F plus the 15 F maroin recommended by IEEE-323 (1974).
U The 433 F coil temperature figure is conservative for several reasons.
First, the coils will be energized before and during a LOCA.
Therefore, the only mechanism affecting the coil temperature rise will be the increase in the ambient temperature and not the change in state (energization) of the coil.
The increase in the ambient temperature will not have as great an effect on the coil temperature rise as the change in state of the coil, becausethegoilsaturationtemperaturebeforetheonsetofaLOCA averages 337 F.
Second, as the coil temperature begins to rise, the resistance of the coil wire increases, thereby reducing the power required by the solenoid, resulting in a reduction in the amound of heat to be dissipated by the valve.
Third, the fifteen minute specified energization of the coil after the onset of the LOCA exceeds actual requirements by a factor of three (3), rather than the 10% margin recommended by IEEE-323 (1974).
5.
The radiation and seismic oualification of the solenoid valve with the new coil is unaffected by the replacement of the coil and the addition of the potting compound for the following reasons:
(a)
All materials utilized in the new coil as well as the potting mategial are rated acceptable in a radiation environment of at least 2 x 10 rads, which exceeds the McGuire requirements by a factor of two (2).
(b)
The addition of the potting compound and the changes in the coil design increase the weight of the solenoid valve by less than 10%, and does not affect the response of the moving parts of the solenoid valve.
The addition of the potting compound increased the rigidity of the solenoid coil, a seismic improvement over the original unpotted design.
Both Duke Power Company and Valcor agree that the preferred method of qualification for Class IE equipment is testing; therefore, a complete qualification program will be pursued to further demonstrate the qualification of these solenoid valves.
Valcor intends to submit a proposal to Duke by January 23,-1981, for additional qualification testing.
Duke will review the Valcor proposal for applicability to Duke nuclear stations and determine whether Valcor and/or Duke will be resoonsible l
for the test program and when and where the testing will be conducted.
l