ML20072R769
| ML20072R769 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 03/15/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072R762 | List: |
| References | |
| TAC-49234, TAC-49323, NUDOCS 8304060315 | |
| Download: ML20072R769 (3) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 30 T0- FACILITY OPERATING LICENSE NO. NPF-2 AND AMENDMENT NO. 22 TO FACILITY OPERATING LICENSE NO. NPF-8 ALABAMA POWER COMPANY j
l JOSEPH M. FARLEY NUCLEAR PLANT, UNIT NOS. 1 AND 2' DOCKET NOS. 50-348 AND 50-364 Introduction By letter dated December 30, 1982 Alabama Power Company (APCo) applied for approval to eliminate the Technical Specifications relating to the 22,000 ppm boron concentration to the Boron Injection Tank (BIT). The proposed change would delete the existing boron requirements upon the BIT and would result in reduced manpower requirements, maintenance costs, and improved plant availability.
The purpose of the BIT is to provide a concentrated source of boron to mitigate the increased reactivity insertion which can result from excessive heat removal transients. Alabama Power Company submitted analyses to' demonstrate that overcooling transients can be accommodated without the highly concentrated boric acid in the BIT, without violating NRC Standard Review Plan (SRP) guidelines, tte have evaluated the analyses herein.
Discussion and Evaluation
- Main Steam Line Break (MSLB) Analysis
. A double-ended rupture of a main steam line causes a rapid-increase in heat.
removal from the primary coolant system, with a resulting increase in reactivity due to moderator feedback. In additten to the negative reactivity inserted by the control rods, boron supplied by the safety injection system is used to control reactivity. Alabama Power Company's analysis of MSLB was performed in conformance with the NRC SRP, using analytical methods which are nearing completion of the NRC staff review.
Our review of the Westinghouse computer codes and methdology indicate reasonable assurance that the conclusions will not be appreciably changed by completion of review. Should our review indicate that revision to the analyses are necessary, APCo would be required to revise the MSLB analyses as appropriate. The rate of decrease in temperature was conservatively over estimated by postulating perfect -
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flow, and by taking no credit for the compensating influence of decay heat and heat stored in structural components. The calculation was performed at zero power, assuining the most reactive Rod Cluster Control Assembly (RCCA) stuck in the withdrawn position. Negative reactivity feedback due to power generation was also deliberately underestimated.
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Consequently, the core reactivity used in the calculation was conservatively high. Boron injection was conservatively underestimated by assuming failure of all but onettrain of safety injection and by taking no credit for the low concentration of boric acid in the emergency core cooling lines between the Refueling Water Storage Tank (RWST) and the reactor cold legs. The analysis was repeated with and without offsite power available. As in previous analyses, (WCAP-9226 January 1978), the case with offsite power available was found to be limiting. During the review, the NRC staff questioned the conservatism of _.
the temperature transient, and the sensitivity of reactivity to cooling. The licensee satisfactorily addressed both concerns in its response to questions 1 and 2.in APCo's letter dated February ll,1983.
The licensee's calculation demonstrated that a MSLB with zero boron concentration in the BIT could be accommodated without experiencing a departure from nucleate boiling (DNBR) equal or less than 1.3.
This satisfies the acceptance criteria of the NRC staff SRP, which does not preclyde fuel damage following a MSLB.
" Credible" Steam Line Break The licensee also analyzed a transient-involving a failed-open steam generator relief, safety or turbine bypass valve. Using conservative assumptions similar to the MSLB calculation, the analysis demonstrated compliance with the criteria of the NRC staff SRP,.
Small Break Loss of Coolant Accident (LOCA)
Westinghouse emergency guidelines advise the operators of Westinghouse designed plants some circumstances exist iir which the core boron concentration following a Small Break (SB) LOCA would be too low to allow transition to cold shutdown, even with 20,000 ppm boron in the BIT. We asked APCo to assess the impact oh
- SSLOCA. In response to question g4 in APCo letter dated February 11, 1983 the licensee has satisfactorily demonstrated that the BIT is not required to raf tigate the consequences of a SBLOCA.
Containment Analysis A boron concentration re' uction in the BIT would affect the containment pressure d
and temperature response for MSLB accident conditions through concomitant i
changes in the mass and energy release rates. The licensee has reanalyzed a spectrum of steam line breaks to determine the ~ magnitude of the impact on contain-ment pressure and temperature response. We evaluated the computer codes, input data and assumptions used in these calculations, and found them to be acceptable.
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The results of the Itcensee's containment analysis show a maximum calculated pressure in the containment of about 46 psig, which is well below the contain-ment design pressure of 54 psig. In addition, the results do not affect the temperature profile previously approved for equipment qualification. The temperature profile was based on LOCA environmental conditions in accordance with NRC staff guidelines.
Safety Summary The principal purpose of maintaining a high boron concentration in the BIT is to mitigate the consequences of a HSLB. The licensee has perfomed an acceptably conservative analysis of a MSLB with zero boron concentration in the BIT. The analysis demonstrates that such a transient can be accomodated without experiencing a departure from nucleate boiling, thereby assuring fuel integrity. This result meets the acceptance criteria of the NRC staff SRP and is acceptable. Results of the licensee's containment analysis show that the maximum calculated pressure and temperature profile is within acceptable limits. The proposed Technical Specification changes are acceptable. Also, no niafor modifications to the plant are proposed, with the exception that the BIT recirculation system and the BIT heat tracing may be deenergized. This Safety Evaluation does not consistute approval for any plant modifications.
Environmental Consideration We have detemined that the amendments do not authorize a t:hange in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this detemination, we have further i:oncluded that the amendments involve an action which is insignificant f'ran the standpoint of-environmental impact. and, pursuant to 10 CFR Sl.5'(d)(4), that an environmental impact statement or negative declaration and environ-mental impact. appraisal need not be prepared in connection with the issuance of these amendments.
' Conclusion
. We have concluded, based on the considerations discussed above, that:.
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(1) because the amendment does not involve a significant increase in the probability.or consequences of an accident previously evaluated, does not create the possibility of an accident of a type different from any e' aluated previously, and does not involve a significant reduction v
in a margin of safety the amendment does not involve a significant hazards consideration. (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and I,3) such activities will be conducted in compliance with the Comunission's regulations and the issuance of this' amendment will not be inimical to the cosanon defense and security or to the health.and safety of the publie..
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Date: March 15,' 1983 l
Principal Contributor:
R. Barrett l
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