ML18058A416
| ML18058A416 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 04/30/1992 |
| From: | Slade G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 9205070152 | |
| Download: ML18058A416 (8) | |
Text
consumers Power l'OWERIN&
MICHl&AN'S l'RO&RESS Palisades Nuclear Plant:
27780 Blue Star Memorial Highway, Covert, Ml 49043 April 30, 1992 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
REGULATORY GUIDE 1.97 OUTSTANDING ITEMS GB Slade General Manager During the week of January 13-17, 1992, NRC Region III personnel performed an inspection of Palisades compliance with the requirements of Regulatory Guide 1.97, Instrumentation for Light-Water Cooled Nuclear Power Plants to Assess Plant and* Environs Conditions During and Following an Accident.
During the course of this inspection, it was identified that Palisades was not in strict compliance with the guidance of the Regulatory Guide in areas related to the identification of RG 1.97 instrumentation, calibration of RG 1.97 instrumentation, and isolation of RG 1.97 instrumentation from non-Class lE components.
Additionally, internal reviews of the Palisades design bases by our Configuration Control Program (CCP) group have recently identified instances where instrumentation, provided to meet Regulatory Guide 1.97 Category 2 guidance, was not environmentally qualified. The CCP group further identified that cables for redundant containment isolation valve position indicators do not meet the Regulatory Guide 1.97 Category 1 guidance related to electrical separation.
The attachment to this letter addresses each of these items and identifies our plans and schedule for bringing each of these items into compliance with the guidance of Regulatory Guide 1.97. Justification for deviation from the guidance of Regulatory Guide 1.97 for two of the items, main steam radiation monitors environmental qualification and containment isolation valve cable separation, is provided in the Attachment.
Your review and approval of these deviations is requested.
~/A~----
~~a;e General Manager CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades Attachment 9205070152 920430 -- -~-
PDR ADOCK 05000255 p
.~;---
ATTACHMENT Consumers Power Company Palisades Plant Docket 50-255 April 30, 1992 6 Pages
I I.
UNIQUE. IDENTIFICATION OF REGULATORY GUIDE 1. 97 INSTRUMENTS Table I, Item 8 of Regulatory Guide I.97 states that Type A, B and C instruments designated as Categories I and 2 should be specifically identified with a common designation on the control panels to allow the operator to easily discern that they are intended for use under accident conditions.
Palisades does have a method of identifying equipment located in a harsh environment which is environmentally qualified. This method consists of placing blue equipment identifiers on the control panels near the instrumentation.
The majority of the RG I.97 components were identified by this method, however several RG I.97 components were not identified as the particular instrument loops did not contain components located in a harsh environment. To address this concern, the remaining RG I.97 components required to be distinctly labeled will be provided with blue equipment identifiers. Appropriate engineering specifications for labeling control panels will be revised to require that the blue tags be provided for environmentally qualified equipment as well as Category I-and 2, Type A, B and C Regulatory Guide I.97 instruments.
Relabeling of the control room components will be completed by June 30, I992.
I I.
CALIBRATION OF REGULATORY GUIDE I. 97 INSTRUMENTATION Table I, Item IO of Regulatory Guide I.97 states that calibration programs should be specified to maintain the capability of the monitoring instrumentation. During the course of the NRC inspection it was identified that electrical instrumentation loops (ammeters, voltmeters, wattmeters) used to monitor the status of standby power and component cooling water flow were not included in a periodic calibration program.
These instrument loops were last calibrated in I986.
To correct this deficiency, all uncalibrated instrument loops identified during the course of the inspection have been calibrated. These instruments will be included in a periodic calibration program.
Incorporation of these instruments into our periodic activities program will be complete by May IS, I992.
Additionally, the FSAR list of RG I.97 instruments will be reviewed to assure that these instrument loops are included in a periodic calibration program.
This review will be completed by May 3I, I992.
III.
ISOLATION OF REGULATORY GUIDE 1.97 INSTRUMENTATION Table I, Item 1 of Regulatory Guide I.97 states that Category I instrumentation should be electrically independent and physically separated from each other and from equipment not classified as important to safety. During the course of the NRC inspection, several areas were identified where the isolation of RG I.97 instrumentation loops from non-Class IE components were not in conformance with the guidance.
Each of the identified isolation discrepancies is addressed below:
I. One channel of the redundant Class IE pressurizer level instruments was found to be connected to the non-Class IE Critical Function Monitoring System (CFMS) computer input termination cabinet. The cable should have been routed to
the Class IE right channel input termination cabinet to provide electrical isolation between Class IE and non-Class IE circuits. As a result of this finding, the pressurizer level cable was rerouted by Specification Change SC-92-02I to the correct termination cabinet. This modification was completed during the I992 refueling outage.
Further information related to this item is provided in Palisades Licensee Event Report 92-005 dated February I4, I992.
While designing the routing for the cable to the Class IE computer input termination cabinet, it was discovered that cabl~ for the redundant pressurizer level channel was routed in the same cable tray. Routing of these circuits in the same tray is a condition outside of the Palisades design basis for cable separation.
Following this discovery, the cables were rerouted to provide for electrical separation as required by the FSAR.
Further information related to electrical separation deficiencies is provided in Palisades Licensee Event Report 9I-OI4, Supplement 2 dated March IO, I992.
- 2.
Palisades letter to the NRC dated April 30, I986 indicated that credit was taken for four pressure instrument loops per steam generator to meet RG I.97 guidance for Type A, Category I variables. Only two instrument loops per steam generator are specified as being required by RG I.97.
During the course of the recent NRC inspection, it was identified that one of the four steam generator pressure loops per steam generator did not meet guidance for electrical isolation as identified by RG I.97. These two channel A steam generator pressure instrument loops provide input to a non-Class IE datalogger.
The isolation devices (thermistor/zener diode) used to isolate these inputs from the datalogger were previously reviewed and approved for use during the Palisades Systematic Evaluation Program.
Documentation of this review is provided in Section 4.2.3 of NUREG-0820, Integrated Plant Safety Assessment, Systematic Evaluation Program, Palisades Plant, dated October I982.
To resolve this discrepancy, Palisades intends to take credit for two of the four pressure loops on each steam generator to meet the redundancy requirements of RG I.97.
The two instrument loops on each steam generator chosen will meet all requirements for electrical isolation as defined by RG I.97. The two channel A pressure loops will not be relied upon to meet RG I.97 requirements.
Before October 30, I992, an FSAR revision will be made to correct this commitment.
- 3.
Electrical isolation of RG I.97 Category I variables steam generator pressure and pressurizer pressure from non-Class IE components is provided by resistor isolators.
Discussions with the NRC inspector reviewing RG 1.97 indicate that the NRC does not consider that this method 2
of isolation meets the intent of Regulatory Guide 1.75, Physical Independence of Electric Systems.
The subject of isolation of the Reactor Protection System from nonsafety systems including qualifications of isolation devices was addressed as Topic VII.I.A of the Palisades Systematic Evaluation Program.
As part of this evaluation, Palisades committed to install lOOK-ohm isolation resistors in selected instrument loops to provide the required isolation. Letters to the NRC, dated May 27, and August 10, 1983, provided an engineering evaluation of the adequacy of this isolation method when used in current loops of the type installed at Palisades.
We continue to believe that use of the lOOK-ohm isolation resistors provides sufficient protection to assure that application of the maximum credible voltage or current to the non-Class lE side of the resistor will not degrade operation of the Class lE side below acceptable levels.
We do, however, intend to perform testing of the lOOK-ohm resistor isolation configuration to confirm the adequacy of this isolation method.
Results of this testing will be provided to the NRC by December 31, 1992.
- 4.
In accordance with RG 1.97 guidance for Category 1 variables, two redundant pressurizer pressure instrument loops are provided.
One loop (PT-01058) meets all of the guidance of RG 1.97 for electrical and physical independence.
The second loop (PT-0105A) was found to be incorrectly wired to the non-Class lE primary instrumentation processor and feedwater purity datalogger computers without adequate electrical isolation.
To resolve this item, electrical isolation was provided in the PT-0105A instrument loop to isolate the signals going to the non-Class lE computers.
This isolation consists of lOOK-ohm isolation resistors as described in Item 3 above.
Installation of this modification was completed during the recent refueling outage.
Further information related to this item is provided in Palisades Licensee Event Report 92-011 dated March 13, 1992.
- 5.
During the review of the containment hydrogen monitoring system, the NRC inspector questioned the qualification of isolators which provide signals to a non-Class lE recorder.
Vendor documentation for 'this isolator was provided to the inspector. This documentation states that the function of the output isolation module is to prevent damaging voltage appearing on the output terminals from affecting the input circuits.
No qualification documentation was found for this isolator. The inspector informed us that this isolator model did not appear on a list of acceptable isolators provided in NUREG-1342, A Status Report Regarding Industry Implementation of Safety Parameter Display Systems, and thus was considered to be unqualified.
3
To resolve this discrepancy, we intend to test this isolation module to the requirements of IEEE-384 or to replace the module with a previously qualified isolator type. Testing of the module, if performed, will be completed by December 31, 1992.
If the module cannot be successfully qualified, it will be replaced during the
- 1993 Refueling Outage currently scheduled to begin in the second quarter of 1993.
4 Based on the number of electrical isolation discrepancies identified during the course of the Regulatory Guide 1.97 inspection, Consumers Power Company intends to review all Category 1 instrumentation loops to verify that adequate electrical isolation is provided. This review will be completed by June 30, 1992.
IV.
ENVIRONMENTAL QUALIFICATION OF REGULATORY GUIDE 1.97 CATEGORY 2 INSTRUMENTS Recent internal reviews of our Environmental Qualification program have identified three Regulatory Guide 1.97 Category 2 instrumentation loops which are not environmentally qualified for all design basis events to which they may be subjected.
For two of these instrument loops, we intend to replace the components with qualified equipment or relocate the unqualified equipment outside of the harsh environment.
For the third instrumentation loop, we believe that sufficient justification exists for deviating from the guidance of Regulatory Guide 1.97 regarding environmental qualification of the equipment.
The following sections provide a description of each of these discrepancies and our plans and schedule for resolving each item.
- 1. Table 3 of Regulatory Guide 1.97 identifies RHR Heat Exchanger Outlet Temperature as a Type D, Category 2 variable. Recently, it was determined that the temperature element (RTD) selected to indicate this variable is located in a harsh environment and is not environmentally qualified. The temperature element is located in an area outside of containment which would be subject to increased temperature and radiation levels following a loss of coolant accident.
To resolve this discrepancy, the temperature element and cable will be replaced with environmentally qualified components.
Replacement of these components will be completed by September 1, 1992.
Further information related to the qualification of this temperature element is provided in Licensee Event Report 92-006 dated February 19, 1992.
- 2.
Table 3 of Regulatory Guide 1.97 identifies plant vent stack flow rate as a Type E, Category 2 variable. Recently, it was determined that the differential pressure transmitter selected to provide indication for this parameter is located in a harsh environment and is not environmentally qualified.
An alternate instrument is available outside of the harsh environment to provide the required vent stack flow rate information.
However, the differential pressure transmitter also provides a signal to the stack radioactive gaseous effluent monitor which is used to control sample flow rate.
Thus, failure of the vent stack differential pressure transmitter due to a harsh environment could cause failure of the effluent
monitor.
To resolve this discrepancy, the following corrective actions have been or will be performed:
- a. A temporary modification (TM} was installed on the radioactive gaseous effluent monitor (RGEM} system to electronically simulate the flow conditions expected for normal operation of the HVAC system. This TM precludes a failure of the vent stack flow rate instrument from affecting operation of RGEM.
This TM was completed prior to startup from the recent refueling outage.
- b.
The vent stack flow rate transmitter will be replaced with an environmentally qualified flow transmitter or relocated to an area outside of the harsh environment.
This modification will be completed by September 1, 1992.
For further information related to the vent stack flow rate
- transmitter refer to Licensee Event Report 92-013 dated March 18, 1992.
5
- 3. Table 3 of Regulatory Guide 1.97 identifies monitoring of the radiation release path from the steam generator safety relief and atmospheric dump valves as a Type E, Category 2 variable.
To provide indication of this variable, Palisades installed radiation monitors on each steam line in an area outside of containment. This area is defined as a harsh environment for a main steam line break (MSLB} outside of containment. The installed radiation monitors are not qualified to operate in this harsh environment.
To resolve this discrepancy, CPCo requests approval to deviate from the RG 1.97 guidance related to environmental qualification of the main steam radiation monitors. Justification for this deviation is based on the following:
- a.
The main steam radiation monitors are used to quantify radiation releases for a steam generator tube rupture.
The steam generator tube rupture event does not result in a harsh environment in the area containing the radiation monitors.
Thus the main steam radiation monitors do not need to be environmentally qualified.
- b.
The function of the main steam line radiation monitors is to calculate the potential offsite dose which could occur following a release through the steam generator safety relief or atmospheric dump valves.
An alternate method of performing this calculation is provided by the backup High Range Effluent Monitors located on the auxiliary building roof.
Use of this backup method is included in Plant Emergency Implantation Procedure El-6.0, Offsite Dose Calculation and Recommendations for Protective Actions.
For further information related to the main steam line radiation monitors refer to Licensee Event Report 92-012 dated March 16, 1992.
_J
V.
ELECTRICAL SEPARATION OF CONTAINMENT ISOLATION VALVE POSITION SWITCHES
. Table 3 of Regulatory Guide 1.97 identifies containment isolation valve position as a Type B, Category 1 variable.
Recent internal evaluations of cable separation at Palisades have identified that the position indication circuits for eight sets of redundant containment isolation valves share a common raceway.
The lack of cable separation for these valves is a deviation from the guidance on redundancy provided in Regulatory Guide 1.97 and the Palisades design basis.
The eight sets of containment isolation valves and their functions are:
CONTROL VALVE PENETRATION NUMBER FUNCTION CV1910, 1911 40 PCS SAMPLE CV1064, 1065 25 CWRT VENT TO STACK CV1002, 1007 47 PCS DRAIN TANK CV1036, 1038 49 CWRT OUTLET CV1044, 1045 69 CWRT PUMP SUCTION CVllOl, 1102 46 CONTAINMENT VENT HEADER TO WASTE GAS 6
CV1103, 1104 52 SUMP DRAIN TO DIRTY WASTE TANKS CV1501, 1502 38 STEAM HEATING RETURN PCS - Primary Coolant System CWRT - Clean Waste Receiver Tank To resolve this discrepancy, CPCo requests approval to deviate from the RG 1.97 guidance related to electrical separation for containment isolation valve position indication. Justification for this deviation is based on the following:
- 1.
The Palisades containment isolation valves are pneumatically operated and fail in the closed (i.e.,
safe) position on loss of either electric power or air pressure.
- 2.
Lack of position indication would not result in misleading the operator.
The operator merely has to place the isolation valve handswitch in the closed position to assure that power is removed from the solenoid operator thus closing the valve.
- 3.
The containment isolation valves for which this is a concern are in systems which are not needed for safe shutdown of the plant after an accident. Therefore, the safe position of the valves is the closed position.
The operator would have no need to open the valves.
Additional information related to electrical separation issues at Palisades is provided in Licensee Event Report 91-012, Supplement 2 dated March 10, 1992.