ML20070U817
| ML20070U817 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 04/05/1991 |
| From: | Zach J WISCONSIN ELECTRIC POWER CO. |
| To: | Martin T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| CON-NRC-91-114 DIRNPD-91-038, DIRNPD-91-38, NUDOCS 9104100027 | |
| Download: ML20070U817 (6) | |
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- 31 v, tamp ro b 7 4$ w*c3ee w 53201 DIRNPD-91-038 NRC-91-114 April 5, 1991 Mr. T.
O. Martin, Director Division of Reactor Safety U. S. NUCLEAR REOULATORY COMMISSION Region III 799 Roosevelt Rcid Glen Ellyn, Illinois 60137 Gentlemen:
D9_QKETS 50-166 AND 50-301 RESPONSE TO NOTICE OF VIOLATION INSPECTION REPORT 50-266/90026 anC JiO-3 01/4 QQ25 POINT BEtCH NUCLEAR PLANT. JNITS 1 and 2 t
Forwarded with a letter dated March 7, 1991, we received the subject Inspection Report and a Notice of Violation.
The report referred to the Special Maintenance Team Inspection conducted by the NRC during the periods January 7 to 11 and January 22 to 25, 1991.
During that incpection, your staff identified certain activities which appeared to be in violation of NRC requirements.
These conditions were identified in the Notice of Viole' an.
The Notice stater that contrary to the requirements of 10 CrR 50 Appendix B, criterion XVI, measures to assure that conditions adverse to quality are promptly identified and corrected were not properly established.
The Notice cited two specific examples to support this finding.
The first concerned the failure to resolve the situr. tion where eight safety-related motor-operated valves (MOV) ured tor que switches of melamine materials; the second concerned the lack of prompt carrective action to resolve a de ground detector alarm set-point problem that was identified on June 4, 1990.
He have evaluated the Notice of Violation and have concluded that the facts rege* ding these examples are essentially correct and that these events are properly characterized as a Severity Level IV violation.
The ettachments to this letter present our discussion and reply to the Notice of Violation.
In these discussions, we have identified the corrective actions taken to date and the results achieved, additional corrective actions that will be taken to avoid further violations of this nature, and the date full compliance will be achieved.
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NRC Document Cortrol Desk April 5, 1991 Page 2 P) ease contact us if you have any questions concerning our actions in this matter.
Very truly yours, cl,v Sae-q.
Jahtu J.
Zach Diseucor Nuclear Power Enclosure Copies to NRC Document Control Desk NRC Resident Inspector
BIEEQi!.EE TO NQTJRE OF VIOLATION POINT BEACF NUCLEAR PLANT As a result of the inspection conducted from January 7-11 and 22-25, 1991, and in accordance with 10 CFR Part 2, Appendix C -
General Statement of Policy and Procedure for NRC Enforcement Actions (1990), the following violation was identified:
1.
10 CFR 50, Appendix B, Criterion XVI, as implemented by the Point Beach Quality Assurance Mu ual, requires that measures be established to assure that conditions adverse to quality are promptly identified and corrected.
Contrary to the above:
MOV Toraus_ Switches A.
Prompt corrective action was not taken to resolve the situation where eight safety related motor operated valves (MOV) used torque switches made of melamine material.
Torque switches made of melamine were subject to a common mode failure as described in a 10 CFR Part 21 notification issued by Limitorque Corporation on November 23, 1988.
At the time of this inspection, eight safety related MOVs ctill contained the suspect switches.
Responoe_:
The Limitorque 10 CFR Part 21 notification dated November 23, 1988 and referenced in this violation, involves Limitorque SMB Model 00 and SMB 000 valve operators that use torque switches made of melamine material.
This notice was received during a time period in which the plant maintenance engineering was undergoing a reorganization.
During the reorganization this Limitorque notification was not properly tracked and no evaluation was
-performed.
Although the maintenance engineer directly involved with maintenance activities of the plant's MOVs was not aware that the above referenced part 21 notification had not been formally evaluated, he was aware of the exintence of the issue and was implementing the replacement of theca torque switches in the planned preventive maintenance program for MOVs.
Plant maintenance records demonstrate that any MOV maintenance performed during 1988 or later has included replacement of melamine torque switches.
There are 98 SMB 00 and SMB 000 valve operators at Point Beach that are safety related and cculd potentially contain these torque switches.
To date, we have inspected and replaced, as appropriate, the melamine torque switches in 86 (87%) of the 98 safety related SMB OG and SMB 000 valve operators.
Current maintenance records of stfety related MOVs show that there are eight MOVs that have the aclamine torque switches and four additional MOVs that may potentially have melamine torque switches.
- 7. srcond Limitorque 10 CFR Part 21 notice dated September 29, 1989, is associated with the fiber spacers under the contact bridge and af fe "ts the same torque switches aGdressed by the November 2 3, 1988 notice on the melamine torque switches.
This relationship was documented in our evaluation of the September 29, 1.989 notice.
In that evaluation we had committed to replacing the melamine torque
switches through a planned preventive maintenance program by 1993.
o
.C.oIIeClivolgM The need for en improved commitment tracking system has previously been identified.
An improved departmental open item tracking system has been implemented to prevent future lost or overdue evaluations and corrective actions.
This system provides for prompt identification and assignment of responsibility, priority, and due date for evaluations and associated corrective actions, computerized tracking of open items, and independent escalating notification for overdue items.
We believe this failure to properly document an evaluation of the November 23, 1988 10 CTR Part 21 notice was an isolated event and should not occur again, given our new tracking system.
We are in the process of documenting an evaluation of this notice and preparing a justification for continued operation (JCO) for the 12 safety-related valve operators that potentially may still contain melamine torque switches.
This evaluation and the JCOs for the 12 valves will be completed by April 30, 1991.
As discussed above, our schedule for completing the replacement of melamine torque switches on safety related MOVs has been scheduled during planned preventive maintenance through 1993.
Based on the results of the JCOs for these valves, this schedule may be accelerated.
DC SYSTEM GROUNDS B.
Prompt corrective action was not taken to resolve a dc ground detector alarm set-point problem that was identified by the licensee on June 4, 1990.
Results of a monthly surveillance check showed that a ground of approximately 5 ohms on station Battery D06 had gone undetected by the de ground detector alarm circuit.
Similar problems with de ground problems were identified in NRC Information Notice (IN) 88-86 and 88-86, Supplement 1.
Corrective actions to resolve this problem had not been fully implemented as cf the time of this inspection in January 1991.
Resconse_1 During perforraauce or monthly battery Routine Maintenance Procedure
( RMP) -4 6, on June 4, 1990, a ;cound, calculated to be approximately 20 Ohms, was identified on the B-train safety related DC bua supplied by battery D06.
The ground detection alarm on charger D08, the on-line charger, did not alarm to indicate thic condition.
The ground detection alarm setpoints are established at approximately 500 Ohms; therefore, this ground should have resulted in an alarm condition.
The previous month's ground calculation on battery D06 was 183 KOhms.
The ground was cleared on June 6,
- 1990, by Maintenance Work Request (MWR) 902655.
The ground was determined to be on the non-safety related portion of the circuit specifically associated with the turbine independent overspeed protection system.
MWR 902796 was issued on July 10, 1990, to investigate the problem with the ground alarm.
Working under this MWR, it was determined 2
- that the ground alarm would not actuate for grounds of 500 Ohms, the alarm setpoint.
Satisfactory operation of the ground detector alarm at 500 Ohms had been previously proven during installation of Modification Request (KR)85-176, which was completed on July 31, 1987.
We believe the degradation in ground alarm performance is a result of relay magnetization.
Small values of ground current, always present on a DC system, can magnetize the ground detector relay coil, such that the relay becomes less sensitive to ground currents in the opposite direction.
We subsequently determined that resistor 13R in the ground detector circuit should be changed from a value of 4990 Ohms to 3820 Ohms, in order for the ground alarm to occur at 500 Ohms.
During the time of the NRC Maintenance Team Inspection, it appeared that this change of resistance values had been made without proper cuthorization and the required change to the RMP-46 calculations had not been made.
Subsequent to the inspection, our investigation and field verification showed that the circuit change had been made for troubleshooting only, and the ground alarm system had been returned to the approved design condition.
Thus, no unatthorized modification occurred, and no revision to RMP-46 was required.
The troubleshooting work plan in MWR 902796 was not completed due to lack of adequate follow-up by plant personnel.
The ground alarm circuit was left in a condition where it would not alarm for a ground at the design setpoint of 500 Ohms.
Repair, modification, or compensatory action should have been undertaken at that time to correct the situation but was not.
For the two year period preceding March, 1991, we have reviewed the monthly ground resistance calculations on the station batteries and DC system.
These readings are summarized in the following table.
BATTERY DOS D06 D105 D106 AVERAGE 513kn 605KO 1000KO 866KO LOWEST 37KO 73.5KO' 1000KO 140KO
- Not counting 20 Ohm ground noted June 4, 1990 We believe these figures demonstrate that the overall condition of our DC systems for the past two years hac been excellent, and that grounds are very infrequent.
CORMiCTIVE ACTIONS Because the installed Westinghouse charger ground detectors may not alarm at values below the alarm setpoint, we have implemented monitoring of ground potentials on busses supplied by batteries DOS and D06 once each operating shift.
The acceptance criterion will be comparable to that specified in RMP-46.
RMP-46 was revised on December 12, 1990, to add a 20 KOhm acceptance criterion to DC bus grounds calculated from battery bus voltage.
This value far exceeds ground values discussed in IN 88-86.
This monitoring will continue until the ground detectors on the Westinghouse chargers have been proven capable of reliably alarming the ground condition, or until they are modified to correct the deficiency.
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- Sinco the ground alarm on charger D08 cxpsrienced on unexplcinsd setpoint shift, vc will check the ground alarms on Westinghouso chargers D07, D08, and D09 to determine the alarm setpoint.
This will be completed by April 7, 1991.
Please note that it will not be necessary to perform this test on chargers D107, D10o, and D109, since these chargers were produced by a different manufacturer, have a different type of ground detection circuit, and have reliable indication for grounds significantly above values commonly used in the industry.
Non-Conformance Report (NCR) N-91-028 was written January 24, 1991, to document the failure of the ground alarm to actuate for a ground less than the alarm setpoint.
Our evaluation for this NCR will be completed on April 15, 1991.
This evaluation will address the reportability and operability implications of this event.
In the inspection report which documented the Notice of Violation, there was a statement that the licensee's evaluation of NRC IN GB-86 concentrated on the financial aspects, equipment, and manpower necessary.to change the DC system.
Central to our evaluations was our assessment that the sophisticated equipment necessary to locate high magnitude grounds without momentarily disconnecting vital equipment was not readily available at the tjas of the IN.
This equipment has subsequently become available.
Ir September 1990, Point Beach purchased a sophisticated DC ground location unit.
At the time of the Maintenance Inspection, this unit was undergoing trial use and evaluation.
Since the inspection the unit has been incorporated into plant-wide use.
We anticipate that this equipment will give us the capability to locate grounds in excens of the present 20 KOhms acceptance criteria without disconnecting vital loads.
Also, in rceponse to our evaluation of IN 88-86 supplement 1, we completed a calculation on February 7, 1991, recommending that the DC ground alarm setpoint be raised from the current 500 Ohm value to approximately 16 Kohms.
This value was chosen to ensure that loads which are r79cted to fail de-energized do in fact de-energize, even l'
'.ha presence of DC bus ground.
Since the presently insta11eJ destinghouse ground detectors are not sensitive enough to actuate at such a high ground resistence, MR 91-067 was initiated on February 21, 1991, to raise the DC ground alarm setpoint and replace the ground detection circuits.
The conceptual design for this modification is scheduled to be completed by August 1,
1991.
'4e expect the modification to be installed and accepted by January 21, 1992.
STATUS OF COMPLIANCE Considering the excellent history of DC system reliability with respect to grounds, we consider that monitoring DC bus voltage on a once per shift basis to determine DC bus grounds is adequate compensatory action to resolve this item from the Notice of Violation, until the permanent corrective actions are completed.
As noted above, this monitoring has already been implemented.
The installation of MR 91-067 to improve the ground resistance detectors of the Westinghouse battery chargers will bring the DC system into full compliance with 10 CFR 50, Appendix B, Criterion XVI.
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