ML20214R587
| ML20214R587 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 11/24/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20214R555 | List: |
| References | |
| NUDOCS 8612080030 | |
| Download: ML20214R587 (2) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO MARK I CONTAINMENT PROGRAM - VACUUM BREAKER INTEGRITY POWER AUTHORITY OF THE STATE OF NEW YORK JAMES A. FITZPATRICK NUCLEAR POWER PLANT DOCKET N0.: 50-333 I.
INTRODUCTION In addition to the evaluation of the suppression chamber, torus-attached piping, pressure relieving lines, and other components under the newly defined loadings, the Mark I containment program required the assurance of the structural integrity of vacuum breakers during operation in all Mark I plants. This additional requirement was categorized as a separate effort, as the adequacy of other components was already discussed in a separate Safety Evaluation.
The Franklin Research Center (FRC) has performed an evaluation of the structural integrity of vacuum breakers at the James A. FitzPatrick Nuclear Power Plant (FitzPatrick) for the NRC staff. Results of the review are reported in the attached document, TER-C5506-318 " Structural Evaluation of the Vacuum Breakers (Mark I Containment Program), New York Power Authority, James A. FitzPatrick Nuclear Power Plant." FRC has concluded that vacuum breakers at FitzPatrick will provide adequate margins of safety under the revised loadings in the Mark I containment for all operating conditions and, therefore, need not be modified. The staff reviewed the attached document and concurs with the FRC findings.
II. DISCUSSION In the FitzPatrick Mark I containment, there are four 30" external type vacuum breakers (manufactured by Atwood - Morrill) mounted on two 30" external pipes connecting the main vent line and wetwell. Loadings on Mark I structures and vacuum breakers are based on the General Electric Company Report, NED0-21888, " Mark I Containment Program Load Definition Report," Revision 2, dated November, 1981. For vacuum breakers, the loadings included are gravity, seismic, and hydrodynamic loads. The hydrodynamic forcing functions were developed by Continuum Dynamics, Inc.
by using a dynamic model of a Mark I pressure suppression system and the full scale test facility data. The system model was capable of predicting pressure transients at specific locations in the vent system.
Loading across the vacuum breaker disc caused by pressure differentials based on test data was thus quantified as a function of time. This work was reviewed and approved by NRC on December 24, 1984. Loadings were combined according to the FSAR commitments.
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T' To determine the structural integrity of the vacuum breakers, results from a finite element model and ANSYS program analyses were compared with design limits specified in the ASME Boiler and Pressure Vessel Code,Section III, Division 1, Subsection NC, 1977 Edition and addenda up to Sunner 1977.
It was found that the hydrodynamic chugging force at FitzFatrick will not significantly increase the impact velocity on vacuum breakers to cause any additional loading. Since the original design margin does not need to be increased, the licensee concluded that no modifications are needed on the vacuum breakers. The analytical methodology is adequate and the finding is acceptable.
III. CONCLUSION The licensee has found that safety margins of the FitzPatrick vacuum breakers were not affected by the hydrodynamic chugging force. The methodology of the analysis and the conclusions are acceptable.
Principal Contributor:
H. Shaw Dated: November 24, 1986 9
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