ML20030A997
| ML20030A997 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 07/22/1981 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML20030A996 | List: |
| References | |
| TASK-03-06, TASK-3-6, TASK-RR NUDOCS 8108050002 | |
| Download: ML20030A997 (27) | |
Text
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ENCLOSURE 2 Big Rock Point Plant I
Seismic Re-eva:.uation Program 4
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Purpose:
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- 1. To satisfy needs of Systematic Evaluation Program topic III-6 l
Seismic Design Considerations
- 2. To provide a deterministic basis to better support as-sumptions and conclusions re-garding seismic contribution to Plant risk as developed in the Big Rock Point Probabil-istic Risk Assessment l
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t Scope: Evaluations will be per-l formed for the following systems i
or portions thereof:
a) Reactor Coolant System b) Main Steam up to and including MSIVs c) cdwater system up to and in-cluding isolation valves d) Portions of other systems directly connected to the RCS up to and including isolation valves e) Control Rod Drive system 1
l Scope continued f) Emergency Condenser including makeup water piping g) Fire system including core spray, backup core spray, enclosure spray, and backup enclosure spray h) Reactor Depressurization system i) Post Incident Cooling system j) Emergency Power Supply k) DC Power system j) Emergency Power Supply
'l) Spent Fuel Pool m) Appropriate portions of struc-tures housing the above systems i
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Scope continued i
Note that this list is essentially identical to the list provided in l
NRC letter dated April 24, 1981.
This list is also essentally ident-ical (with the exception of the in-strument air system *) to the list of critical systems determined by the PRA to be necessary to mitigate all postulated core melt sequences.
Consumers Power Co. may, however, determine that a reduced list is appropriate if all the above systems are not necessary to mitigate a seismic event.
Suitable justification will be pro-vided to support deletion of any system from the above list.
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Scope continued l
- Instrument air is presently needed i
only for demineralized water makeup to the shell side of the emergency condensor.
I The PRA has identified replacement of a one inch manual valve on the redundant. fire water makeup l'ine to the emergency condensor as a desire-able modification.
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This modification would allow the operator to supply fire water to the condensor in the event of f ailure of the normal demineralized water makeup source.
Instrument air, therefore, is not included on the above list.
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Program Elements
- 1. Compile existing BRP plant seismic qualification data for:
+ Structures
- Critical Systems & Components
- Block walls & noncritical equipment presenting potential hazards due to proximity to critical systems.
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Program Elements
- 2. Complete review of D'Appolonia report
- Modify report to reduce conservatism if appropriate.
- Use report results and procedures as input to pre-liminary evaluation criteria.
- Docket revised. report or existing report with qualify-ing comments.
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I Program Elements
- 3. Develop preliminary evaluation j
criteria.
+ Applicable Codes (AISC, ash 1E, j
ANSI /ANS, etc.)
- SEP information & applicable
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NUEEGs, Reg.
Guides, etc.
- BRP FHSR and equipment specs.
- Service Level D vs C l
- Applicability of
& procedures for system walkdown.
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I, Program Elements
- 4. Conduct detailed, systemati~c plant inspection of critical systems and components.
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- Identify vital components on complex systems such as '
control panels.
- Identify other items potentially hazardous to safety related equipment in their immediate vicinity (e.g block walls).
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- Obtain necessary dimensions.
etc. to supplement existing I
documentation.
- Photograph all items to be reviewed.
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Program Elements 4 continued 1
- Judge seismic fragilities of all components using person-nel expert in observation of actual earthquake damage.
- Observe adequacy of bracing and anchorages.
- Identify most fragile lines &
comp onents.
Determine and implement desirable plant changes to judgment criteria for housekeeping items plus small lines below sizes considered by applicable codes.
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Program Elements 4 continued
- Take sample measurements of equipment responses to determine fundamental frequencies (hand excitation, accelerometer, oscilloscope).
- Separate items inaccessible during plant operation for walkdown during outage.
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l Program Elements
- 5. Finalize evaluation program.
Select the best option for i
evaluation of each component based on avai:.able data.
Options include qualification by similarity, test, simplified analysis, detailed analysis, replacement, sampling, etc.
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l Program Elements l
6.
Prioritize BRP systems for i
evaluation according to:
+ Criticality of system to l
plant operation or shutdown including degree of redundancy General ranking will be RC pressure boundary, shutdown
- systems, ECCS related syste.ms in that order.
- Perceived fragilities based on walkdowns.
- Accessibility during operation e
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Program Elements I
- 7. Finalize evaluation criteria to be applied to each system and method, to include ground and floor response
- spectra, damping, simplified analysis methods, etc.
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i Program Elements
- 8. Conduct evaluation of each l
included component or piping system by one or a combination of the following methods:
a) Simplified Analysis
- Conduct single-degr.ee-of-freedom analysis where justified, (compact structures whose i
fundamental mode is obviously rocking), compute fundamental frequency to determine the evaluation g-level from floor re-sponse spectra, check the anchorage capacity.
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Program Elements j
8: a continued l
- Conduct simple finite element analysis where justifie d.
- Formulate conceptual designs of added bracing and. anchorages where require d.
Program Elements I
8.b) Detailed Analysis
+ Conduct dynamic analysis l
where other analysis methods can not be l
justified.
- Formulate conceptual l
designs of added bracing &
anchorages where required.
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Program Elements 8.c) On-Site Testing
- Perform low-level excitation tests on BRP equipment to measure model L
frequencies, mode shapes, model dampings.
- Use test results to estimate participation f actors and hence maximum response from floor spectra without need of equipment structural detail for modeling.
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Program Elements l
I 8.c continued a
- Use test results of BRP l
equipment to compare with similar equipment at data source plants, show that similar more fragile equipment have withstood seismic events.
+Use measurements of d.amping as input to criteria to justify more realistic assumptions for evaluation.
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8.d) Qualification by Similarity i
- Compare BRP equipment to similar equipment in data i
source plants which withstood seismic events.
Show by analysis or.
testing that data source V
equipment is either similar or more fragile than BRP equipment.
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- Determine as necessary the fragility levels of BRP equipment (maximum tolerable g-level, or pre-ferably qualification spectrum) from existing shake table data for similar equipment.
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i Program Elements 14 l
- 9. Write a Summary Report I
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Program Elements
- 10. Consider interim actions (e.g. temporary systems for added redundancy) where necessary for items of particular safety signific ance.
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Program Elements
- 11. Complete any modifications determ.ined to be necessary on a schedule which will allow completion with plant or other CPCo labor.
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