ML20195D203
| ML20195D203 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 06/15/1988 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8806230066 | |
| Download: ML20195D203 (4) | |
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DUKE POWER GOMPANY P.O. HOX 33180 CHARLOTTE, N.O. 28242 HALH.TUGKER reternose vice rarasomn, (704) am831 NWLeAn rNCTION June 15, 1988 U. S. Nuclear Eagulatory Commission Attentfon: Document Control Desk Washington, D. C. 20555 Subjec't RII/NM Catawba Nuclear Station IE Report 50-413,414/88-07
Dear Sir:
My letter of March 11, 1988 provided additional information subsequent to the subject Inspection for review prior to issuance of the Inspection Report.
Attached is further clarifying information on two items; Violation 413/88-07-03 and Unresolv d Item 414/88-07-08 which concern motor operators for the Hydrogen e
Skinner Fan System Valves and T-Drain installation on Limitorque Motor Operators.
This information supplements that provided in Attachments I and II of my March 11, 1988 letter.
Very truly yours, Y
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Hal B. Tucker
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LTB/26/sbn Attachment xc:
Dr. J. Nelson Grace, Regional Administrator U. S. Nucinar Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. P. K. Van Doorn NRC Resident Inspector Catawba Nuclear Station I
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ATTACHMENT 1 ITEM NUMBER 50-413/88-07-03 Use of unqualified Limitorque Motor Operated Valves inside Unit 1 containment.
, BACKGROUND:
From June 1984 to January 1986, commercial Limitorque actuators were installed on Hydrogen Skimmer System valves IVX1A, IVX2B, 2VX1A and 2VX2B.
The subject valves / actuators were specified as inside active, to the valve manufacturer (Fisher Controls).
In containment, 1984, Duke Power discovered the actuators were not nuclear grade.
Duke Power decided to evaluate acceptability of the actuators in light of the moderate accident environment (upper containment) and design The similarity between safety-related and commercial actut. ors.
commercial actuators were subsequently replaced with fully qualified actuators in January 1986.
Upon review of the acceptability analysis of the commercial actuators, the ir.spection team found the analysis unacceptable.
Specifically, the analysis addressed only the acceptability of the motor but did not take into consideration the limit switch, torque switch and termination means.
DUKE RESPONSE:
Commercial grade Limitorque actuators arc identical, with the exception of control wiring, to the actuator which was qualified under Limitorque Test Report B0003.
The "standard" or commercial grade Limitorque actuator was supplied with aluminum / phenolic limit switch materials and aluminum / phenolic torque switch materials as were tested in P0003.
The supplied terminal block (power only) would have been any of several qualified for this application under Limitorque Test Report B0058.
The table below compares the B0003 tested parameters to the worst-case required parameters for the VX valves:
WORST CASE PARAMETER B0003 REQUIRED Temperature (peak) 250 F 180 F Pressure (peak) 25psig7 15psgg
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Radiation 2.0X10 Rads 6X10 Rads Chemical Spray None 2000-2100 ppm Boron pH 4.0+8.25 Submergence None N/A Operability Time 16 Days 11 minutes post-tOCA
- Based on 20 months normal plus 11 minutes post-LOCA
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Item Number 50-413/88-07-03 Page 2 As can be seen, the tested parameters envelope, with margin, the postulated worst-case environmental conditions with the exception of chemical spray.
The only failures associated with chemical spray were reported in Limitorque Test Report 600198.
The aluminum limit switchgear frame failed 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into the test due to chemical spray but was successfully operated 7 times prior to failure.
As the VX valves are required for only 11 minutes into the LOCA, the limit switch frame is qualified, with margin, for this application.
The control wire supplied with the commercial grade actuator was PVC.
The following is a generic evaluation of PVC wire:
TEMPERATURE Based on Underwriters Laboratories standards (gL83, Segtions 37 & 39)
PVC insulations are tested at a minimum of 121 C ( 250 F) to verify both electrical performance and acceptable mechanical deformation.
Therefore, the PVC insulation design agd production test envelope s the postulated accident temperature of 180 F for this application.
RADIATION EPRI-NP-2129, "Radiation Effects on Organic Materials in Nuclear Plangs", page 3-11, indicates PVC cable insulation is affected after 5X10 Rads.
"Fundamentals of Nuclear Hardening of Electronic Equipment", L.W.7 Rickets, page 122, indicates radiation resistance of PVC to be 1.9X10 Rads.
Additional reference documentation on PfC insulation also indicates a resistance to ragiation above 5.0X10 Rads.
Therefore, for this application, 6X10 Rads, PVC is qualified.
AGING No significant aging mechanism has been identified for PVC.
Reference documentation indicates that degradation of PVC will be accelgrated by the synergetic effect of temperature and radiation above SX10 Rads.
Since the wire was exposed to only normal operation conditions over its installed life of 20 months, no aging degradation would be anticipated.
Additionally, the accident environment to which the insulation would have been exposed is well below the threshold for synergetic effects.
Therefore, PVC wire is qualified for this application.
SUMMARY
It has been demonstrated that the valves in question were qualified for their postulated post-accident environment during the time period, June 1984 to January 1986.
Thus, it is Duke Power Company's position i
that the condition that existed until January 1986 in no way jeopardized l safety of the plant or public.
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e NI"rACHMENT 2 T-DRAIN INSTALLATION ON 2NI-122B BACKGROUND:
One additional concern was identified regarding the installation of T-drains on Limitorque Motor Operators.
During the walkdown T-drains on Limitorque valve No. 2NI-122B were not installed at the low point.
This configuration does not appear to be qualified.
This item was identified to the licensee as Unresolved Item 50-414/87-07-08, T-Drains on Limitorque operator not installed at low point.
, RESPONSE:
Limitorque Qualification Report S0058 states that the operator was tested "in the worst possible position."
This was with the limit switch compartment up and the motor horizontal.
This arrangement allowed all of the moisture condensed in the operator to flow through the motor and subject its insulation to maximum moisture.
The Nuclear Utility Group on Equipment Qualification (NUGEQ)
Limitorque Clarification Report, in Section 2, indicates that Limitorque considers actuators qualified for all orientations, but installations with motor or limit switch compartment oriented down should be minimized.
Section 3 of the NUGEQ report also provides instructions for installation of T-drains when the motor principal axis is vertical.
2NI-122B had T-drains installed in accordance with those requirements.
LimitorqueprovidesnorestrictioNsonoperatororientationotherthan to minimize motor down positions.
2NI-122B met all of the required guidelines and is therefore in an environmentally qualified
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configuration.
2NI-122B VALVE REQUIRED OPERABILITY 2NI-122B is an isolation valve for the NI check valve test header.
The valve is opened for required check valve testing during unit startup and is normally closed during power operetion.
2NI-122B also serves as a containment isolation valve for the $est header penetration and receives S and T closure signals.
The T signal initiates valve closure for containment pressures of one pisg or greater.
For events that release energy into containment that cause harsh environment conditions, 2NI-122B would receive an immediate signal to close.
If opened, it would close and complete its safety function within approximately one minute of signal initiation.
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