ML20138K857
| ML20138K857 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/24/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20138K855 | List: |
| References | |
| NUDOCS 8510310002 | |
| Download: ML20138K857 (3) | |
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a ue UNITED STATES l
NUCLEAR REGULATORY COMMISSION j*
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RE: ANCFORfGE AND SUPPORT OF SAFETY-RELATED ELECTRICAL EQUIPMENT i
NORTHEAST NUCLEAR ENERGY COMPANY l
MILLSTONE NUCLEAR POWE2 STATION, UNIT NO. L DOCKET NO. 50-245
}
1.0 INTRODUCTION AND BACKGROUND
The seismic design evaluations' conducted by the NRC with the Systematic Evaluation Program (SEP) indicated a potential safety concern relative to the anchorage and support of safety-related electrical equipment (Peference 1).
It also concluded that some non-seismic Category I auxiliary items 1
(dolleys, gas bottles, etc.) may be dislodged by an earthquake and damage i
safety-related equipment. The licensee was requested to develop an action t
plan for resolution of this issue and to submit it for NRC review.
The licensee provided a summary of the results of its investigation of the anchorage and support of safety-related electrical equipment in its submittal of April 13, 1981 (Reference ?). The sumary included the components reviewed, i
their location, type of anchorage, and whether a modification of this anchorage was required.
For those components requiring modification, the licensee also provided the type of modification perfonned to upgrade the anchorage.
As a result of the work involved in the replacement of the gas turbine genera-tor batteries, the licensee identified that the supports for these batteries I
were not subjected to the review conducted in response to SEP findings.
In its transmittal of June 14, 1985, (Reference 3) the licensee identified those subsystems which were not reviewed for seismic adequacy in addition to the non-Category I equipment which was identified as requiring seismic restraint to eliminate the potential of causing damage to adjacent IE equipment in the event of an earthquake.
2.0 EVALUATION In Reference 3 the licensee identified the following gas turbine subsystens as being reviewed for seismic adequacy:
Control house containing:
One AC and one DC Motor Control Center Battery Charger Inverter i
Control Panel (Turbine and Generator) i t
j Batteries and Racks
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i The licensee also identified the following non-Category I equipment as being reviend to evaluate the adequacy of existing supports for impact on adjaccrt IE equipment:
Strip Chart Recorder Instrument Rack Two Compartment Heaters Carbon Dioxide Fire Suppression Bottles Air Conditioner The, licensee provided a sumary of the calculations performed for the evaluation of the above identified equipment anchorage and the control house i
structural support and internal framing. The calculations utilized the Safe Shutdown Earthquake (SSE) response spectra which was developed for Millstone I during the SEP review. The peak horizontal acceleration at 27 structural i
damping multiplied by a factor of 1.5 (to account for the participation of high frequency modes) was used for application to the subject equipment.
The analysis utilized three directional seismic loading in addition to the dead-weight of the equipment being evaluated.
The resultant loads and stresses on the supports were computed by adding the deadweight contribution to the l
square-root-sum-of-the-squares of the seismic forces. The acceptance criteria l
for the evaluation of the equipaent anchorage and restraints was that prescribed j
in the AISC Vanual of Steel Construction (8th Edition), and the AWS D1.1-85 l-code for Structural Welding.
l The evaluaticn concluded that all items with existing supports (with the 1
exception of the Strip Chart Recorder Instrument Rack) were adequately supported to withstand the postulated seismic forces.
l Modification of the Instrument Rack requires the installation of a seismic restraint.
j The staff also perfonned a sample review of the calculations performed for the qualification of the following items:
Battery and Battery Pack Replacement Strip Chart Recorder Instrument Rack Restraint i
The AC and DC Motor Control Center j
3.0 CONCLUSION
The staff concluded, based on the review of the licensee evaluat' ion and the sample calculations provided, that the safety related Gas Turbine subsystems and the adjacent non-category I equipment identified above, were adequately supported to withstand postulated earthquake loadings on the ordtr of the safe shutdown earthquake.
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4.0 REFERENCES
1)
D. Eisenhut letter to Northeast titilities (V. Council),
dated January 1,1980 El P. Council letter to the NRC (J. Zvolinski), dated March 22, 1905 3)
Northeast Utilities (J. Opeta) letter and attachrent to tFe f:RC dated Jere la, 1985 5.0 ACKNOWLEDGEMENT Principal Contributor:
Varal A. Manoly, Region I Date: Odtober 24, 1985.
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