ML18079A811
| ML18079A811 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 06/23/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18079A810 | List: |
| References | |
| NUDOCS 7908200128 | |
| Download: ML18079A811 (3) | |
Text
ENCLOSURE SAFETY EVALUATION SALEM NUCLEAR GENERATING STATION, UNIT 2 SEISMIC STRESS ANALYSIS OF SAFETY RELATED EQUIPMENT In a letter dated May 3, 1979, the Public Service Electric and Gas Company submitted their response to the Office of* Inspection and Enforcement Bulletin 79-07, 11Seismic Stress Analysis of Safety Related Equipment.
11 We have reviewed the information provided by the applicants and our evaluation of information submitted is as follows.
With respect to the primary loops (NSSS Scope), the applicants have analyzed the system in accordance with our requirements and we conclude that the system is acceptable.
Therefore, the systems under discussion in this evaluation are in the balance of plant scope.
Subsequent to the receipt of the Office of Inspection and Enforcement Bulletin 79-07, the applicants reanalyzed 43 piping subsystems which comprised the entire Unit 2 residual heat removal system and attached branch lines. These 43 analyses included piping of various configuration and diameters, and constituted a representative sample of the seismic Category I piping at Salem Unit 2.
The reanalysis indicated that the original piping and support design of the residual heat removal system was sufficiently conservative to meet current licensing criteria with only minor changes.
The changes will increase the available design margin in the piping systems to a level consistent with current standards.
However, the systems could perform their function prior to modification, but with lower margin.
The 43 piping subsystems already reanalyzed are expected to be typical of the Unit 2 piping and represent various complex piping con~
figurations in which the effects of all three orthogonal earthquakes will be felt. Therefore, these 43 piping subsystems provide an adequate sample for estimating the effect of the Office of Inspection and Enforcement Bulletin 79-07 on the design of Unit 2 piping.
Consequently, we believe that only a minimal number of hardware changes will be necessary to fully bring the Unit 2 piping seismic design into compliance with our current licensing criteria. The applicants have recently performed a walk-through inspection of the Unit 2 piping and compared the 11as built 11 piping against its piping isometric drawings as required by.the Office of Inspection and Enforcement Bulletin 79-07.
Our Office of Inspection and Enforcement will verify that the Unit 2 piping analyses represent the 11 as built 11 condition.
To fully resolve the issues of the Office of Insp~ction arid Enforcement Bulletin 79-07 for Salem Unit 2, we require that.all affected piping systems,*
not just a sample, be reanalyzed_and modified as* necessary to meet current standards prior to commercial operation.
In sett;ng:conditions for the performance of this reevaluation, we believe that low_ power operation-and power ascension tests can be commenced while-the reevaluation is proceedfr1g without affecting the health and safety of the public. This reevaluation -
schedule essentially assures the capability of shutting the plant-down if necessary.
Our re'quirements are as follows-:. -*
(1)
The applicants must complete the reevaluati6n ~fall seismic Categ~ry I large bore piping (greater than _2 inch nominal pipe.diameter) and-any" small bore piping (2 inches and less in nominal pipe diam~ter) essential to. ~afe shutdown of the plant~-
We must approve this ree~aluation and ascertain the need to complet~ certain r~q~ired hardware changes within 90 days after issuance of an operating license and before Salem Unit 2 exceeds 30 perc~nt power. lf our approval of the reevaluation is not granted by the end nf the 90 day period, Unit 2 must proce~d to a cold shutdown condition. This reevaluation includes not only piping ~tresses, -
but also support loads and stresses:and.a determination that pump and valve.operability is not affected by any increased nozzle loads.
*Our justification for this 90 day lice-nsingcondition is (1) the primary loops---------~-
. have been found acceptable, (2) 43 piping subsystems which comprised the entire Unit 2 residual heat removal systems have been reanalyzed and has indicated that the original piping and support design of the residual heat removal :system was sufficiently conservative to meet current licensing criteria with only minor changes and, (3) the likelihood of occurrence of-a s~fe shutdown earth-quake ~uring this short period of time is small. - ~urther the plant will be maintained in.eithe~ a zero power or low power tbndition*pending completion of this task as discussed above.-
In the unlikely event that a postulated safe shutdown earthquake should occur, we believe that at most ohly*a few piping supports might be.damaged, and that all systems would function as required to achieve a plant shutdown:* Should the reanalysis require any significant hardware changes, we would require their implementation before approving' continued operation.
(2)
The applicants, within 150 days of issuance of an bperating license, must complete the reevaluation of all remaining small bore piping and receive our approval.
Also, all required hardware changes for both laige and small bore piping systems must be completed by this time.' *If our approval of the reevaluation is not granted by the end of the 150 day period, Unit 2 must proceed to a cold shutdown condition.
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- Current estimates are that Unit 2 will* complete its power ascension tests and enter coTPmercial operation approximately 150 days after issuance of an operating license.
Our justification for this 150 day licensing condition is that only small bore piping is being reevaluated during this phase.
These remaining small bore lines are not crtttcal to shutting the plant down because all essential small bore lines will be reevaluated during the initial 90 day period.
Additionally, the initial sample of 43 calculations indicate that the Unit 2 small bore lines are very conservatively designed and no hardware modifications are anticipated. Therefore, due to the initial sample calculations reaffirming the conservatism of the applicant's original design, we believe that our schedule provides reasonable assurance for the protection of the publics health and safety while the reevaluation is completed.