ML18066A228
| ML18066A228 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 07/08/1998 |
| From: | Haskell N CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR GL-87-02, GL-87-2, NUDOCS 9807140096 | |
| Download: ML18066A228 (7) | |
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r A CMS Energy Company Palisades Nuclear Plant Tel: 616 764 2276 27780 Blue Star Memorial Highway Fax: 616 764 2490 July 8, 1998 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Covert, Ml 49043 DOCKET 50-255 - LICENSE DPR PALISADES PLANT Nathan L. Haskell Director. Licensing REPORT OF SQUG ASSESSMENT AT THE PALISADES PLANT FOR THE RESOLUTION OF (USI) A-46 SUBMITTAL - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION On May 23, 1995', Consumers Energy submitted the Summary Report in response to Generic Letter 87-02, 'Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors, Unresolved Safety Issue (USI) A-46." On May 12, 1998, a request for additional information (RAI) was received. This letter provides the Consumers Energy response to that RAI.
The attachment to this letter lists each individual request for information and provides the Consumers Energy response.
SUMMARY
OF COMMITMENTS This letter contains no new commitments and no revisions to existing commitments.
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~than L. Haskell
¢~rector, Licensing CC Administrator, Region Ill, USN RC Project Manager, NRR, USNRC NRC Resident Inspector - Palisades Attachment 9807t40o96 98o7oa r*1 PDR: < ADOCK 05000255.
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ATTACHMENT CONSUMERS ENERGY COMPANY PALISADES PLANT DOCKET 50-255 Response to Request for Additional Information (NRC Letter dated May 12, 1998)
Resolution of Unresolved Safety Issue A-46 5 Pages
ATTACHMENT PALISADES NUCLEAR PLANT RESPONSE TO USI A-46 REQUEST FOR ADDITIONAL INFORMATION N RC letter dated May 12, 1998, requested additional information with respect to Consumers Energy's May 23, 1995, response to Generic Letter 87-02. Below is each of the requests for additional information and the Consumers Energy response.
NRG Request:
- 1.
Describe what reviews were performed to determine if any local operator actions required to safely shutdown the reactor (ie., implement the SSEL [safe shutdown equipment list]) could be affected by potentially adverse environmental conditions (such as loss of lighting, excessive heat or humidity, or in-plant barriers) resulting from the seismic event. Describe how staffing was evaluated and describe the reviews that were conducted to ensure operators had adequate time and resources to respond to such events.
Consumers Energy Response:
As described in GIP-2, Part II, Section 3.2.5, the only potential events which must be considered in the USI A-46 program are a safe shutdown earthquake (SSE) and loss of offsite power (LOOP). The plant operating procedures used to shut down the reactor following a LOOP (loss of AC Power at Palisades) have previously been validated for local operator actions. This includes potentially adverse environmental conditions such as loss of lighting and excessive heat and humidity. Note that the USI A-46 accident scenario (SSE + LOOP) explicitly excludes loss of coolant accidents (LOCA) and high energy line breaks (HELB). Therefore, the heat and humidity conditions in the plant are postulated to be equivalent to those in a LOOP scenario.
The potential for failure of plant structures and equipment is not considered credible at eastern United States earthquake levels. Earthquake experience has shown that typical industrial structures are able to withstand earthquakes larger than the SSEs for eastern United States nuclear plants without collapse or failure. The potential for local failure of architectural features (such as suspended ceilings in the control room) and the potential for adverse seismic spatial interactions in the vicinity of safe shutdown equipment, where local operator actions may by required, was explicitly evaluated as required in GIP-2, Part II, Section 4.5 and Appendix D. For example, this review included a check that the masonry walls near safe shutdown equipment are seismically adequate based on the results of the IE Bulletin 80-11 program.
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The systems and equipment selected for seismic review in the USI A-46 program are those for which Normal, Abnormal, and Emergency Operating Procedures are available to bring the plant from a normal operating mode to a hot shutdown condition. As required by GIP-2, Part II, Sections 3.2.8 and 3.7, the safe shutdown equipment list (SSEL) was reviewed by the plant Operations Department to confirm that it is compatible with these plant procedures. Plant operating procedures were not significantly changed to support a plant safe shutdown as a result of the USI A-46 program. Since these plant procedures had already been validated to ensure that adequate time and resources are available for operators to respond to a LOOP incident, it was not necessary to re-validate these procedures for the USI A-46 program.
(Refer to Summary Report, Tab 3, Attachment D.)
NRG Request:
- 2.
As part of the review, were any control room structures that could impact the operators' ability to respond to the seismic event identified? Such items might include but are not limited to main control room ceiling tiles, non-bolted cabinets, and non-restrained pieces of equipment (ie., computer keyboards, monitors, stands, printers, etc.). Describe how each of these potential sources of interactions has been evaluated and describe the schedule for implementation of the Final resolutions.
Consumers Energy Response:
At the time the walkdowns were conducted for the Summary Report, submittal dated May 23, 1995, no credible interactions within the Control Room were identified. During the Peer Review walkdown of the Control Room, several "seismic housekeeping" issues were noted. These items were addressed in Consumers Energy's letter to the NRC dated November 14, 1997, (question 3 (e)) in which a remodeling project of the Control Room was described. The only item of concern in the peer reviewer's letter that was not addressed by the Control Room remodeling project, is the aluminum lighting diffusers within the suspended ceiling. The diffusers have been added as an item to be resolved along with the other outliers identified in the Summary Report. The schedule for completion of outlier resolution has previously been identified as the second refueling outage following receipt of a site specific Safety Evaluation Report approving the use of the GIP, Revision 2, for the resolution of USI A-46 for Palisades.
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N~C RefJuest:
- 3.
Describe what reviews were performed to determine if any local operator actions were required to reposition "bad actor relays." For any such activities, describe how adverse environmental conditions (such as loss of lighting, excessive heat or humidity, or in-plant barriers) resulting from the seismic event were analyzed and dispositioned. Describe how staffing was evaluated and describe the reviews that were conducted to ensure operators had adequate time and resources to respond to such events.
Consumers Energy Response:
The term "bad actor relays is a colloquial expression which refers to the list of relays in Appendix E of EPRI Report NP-7148. These relays have low seismic ruggedness or demonstrated sensitivity to high frequency vibration. The term used in EPRI NP-7148 characterizes these relays as "low ruggedness" relays.
The only low ruggedness relays that were required for the function of equipment on the Safe Shutdown Equipment List were replaced with qualified relays during the 1998 Refueling Outage. No other operator actions are required to reset relays.
NRG Request:
- 4.
Describe which of the operator actions associated with resetting SSEL equipment affected by postulated relay chatter are considered to be routine and consistent with the skill of the craft. If not considered skill of the craft, what training and operational aids were developed to ensure the operators will perform the actions required to reset affected equipment?
Consumers Energy Response:
There are no actions associated directly with resetting equipment affected by relay chatter. The only operator actions are manipulation of valves to realign systems, and one case where power feeds are realigned due to loss of AC power. All of these actions are considered routine and are directed by existing, symptom based operating procedures. None of these valve manipulation actions are immediate, but will occur over the course of hours and/or days.
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N~C Reguest:
- 5.
Assume the alarms associated with "bad actor relays" are expected to annunciate during the seismic event. Do the operators have to respond to those annunciators and review the annunciator response procedures associated with them for potential action? How would those additional actions impact the operators' ability to implement the Normal, Abnormal, and Emergency Operating Procedures required to place the reactor in a safe shutdown condition?
Consumers Energy Response:
As discussed in our response to Question number 3 above, the term "bad actor" relay is a colloquial expression which does not properly categorize these type of relays. As
- defined in the relay review procedure, EPRI Report NP-7148, these relays are called "low ruggedness" relays.
As described in EPRI Report NP-7148, Section 3.5.3, following an earthquake which causes the turbine to trip and the reactor to scram, 50 to 100 or more alarms are expected to annunciate. In addition to this large number of alarms, there may be several earthquake-induced, spurious alarms resulting from events such as water sloshing in tanks, oil sloshing in transformers, actuation of vibration protective instrumentation on rotating equipment, and contact chatter of relays. When the large number of alarms occurs, the operator will clearly be aware that the plant has tripped.
Plant procedures and operator training require that operators respond to the turbine trip and reactor scram by confirming the scram and trip and checking important levels, temperatures, pressures, flows, and electrical switching resulting from associated power transfers. These confirmatory checks will take more than a minute to complete, during which time the operators will be busy making these checks and not responding to specific alarms. The earthquake motion is assumed to last less than one minute and the cause of the spurious alarms will have gone away during this period while the operators are responding to the plant trip.
The NRC staff and SQUG representatives discussed this topic in detail, including discussions held at a meeting on August 3, 1988, where this was a primary topic. The results of that evaluation and review are summarized in EPRI NP-7148, Section 3.5.3 where the following conclusion is reached.
"Accordingly, there appear to be no reasonable bases or evidence which would suggest that spurious alarms resulting from an earthquake may lead to abnormal operator responses. Therefore, special operating procedures or relay evaluation actions to address potential spurious alarms are not considered warranted and relays affecting alarms need not be seismically adequate."
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The NRC staff accepted the relay functionality review procedure summarized in GIP-2 arid described in detaiUn EPRI NP-7148 (including the above conclusion) in Supplemental Safety Evaluation Report No. 2 on GIP-2. Therefore, Consumers Energy does not consider it necessary to perform any additional reviews of the effect of spurious alarms caused by "low ruggedness" relays or other causes as a result of a seismic event.
NRC Request:
- 6.
To the extent that Normal, Abnormal, and Emergency Operating Procedures were modified to provide plant staff with additional guidance on mitigating the A-46 Seismic Event, describe what training was required and provided to the licensed operators, non-licensed operators, and other plant staff required to respond to such events.
Consumers Energy Response:
No Operating Procedures have been revised as a result of the USI A-46 review.
Operator training on any procedure revisions would be addressed as part of the normal operator training routine.
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