ML19273B300
| ML19273B300 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/19/1979 |
| From: | Engle L, Stolz J Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19273B296 | List: |
| References | |
| NUDOCS 7904060096 | |
| Download: ML19273B300 (5) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORIING AMENDPENT NO. 9 (ARKANSAS POWER AND LIGHT COPPANY I COCKET NO. 50-368 INTRODUCTION By letter dated December 13, 1978 and as supplemented by letters dated December 20, 1978, January 3,1979, January 9,1979 and February 2,1979, the Arkansas Power & Light Company requested changes to the Technical Specifications for Arkansas Nuclear One, Unit 2.
These changes are discussed in Items (1) and (2) below.
Also, based on the changes as described in Item (2) below, an administrative change is required in Paragraph 2 of Section 2.C.(2) of License NPF-6.
This administrative change is discussed in Item (3) below.
DISCUSSION (1) The current Technical Specification 3.6.1.4, " Limiting Conditions for Operation", specifies a minimum-initial containment temperature and pressure of 100 degrees Fahrenheit and a negative 0.7 pounds per square inch gauge, respectively.
Operating experience at Arkansas Nuclear One, Unit 2 has caused the Arkansas Power & Light Company to conclude that the current specification is too restrictive.
Technical Specification, Figure 3.6-1, as specificed in Technical Specification 3.6.1.4 shows the limiting conditions for containment internal pressure, temperature, and humidity for plant operations in Modes 4, 3, 2 and 1 (hot shutdcyn, not standby, startup, and power operation). The bounding parameters considered in developing Figure 3.6-1 were the peak containment pressure due to the loss-of-ccolant accident and the maximum external differential pressure due to the inadvertent actuation of the containment spray system.
In order to provide a greater margin to the containment design limit from the effects of heatup during startup operations, the lower limitations on initial containment pressure, temperature and hunidity presently stipulated in Technical Specification 3.6.l.4 are based on the design external differential pressure of a negative 3.5 pcunds per square inch gauge which limits the mininum temperature and pressure to 100 degrees Fahrenheit and a negative 0.7 pounds per square inch gauge.
79040600 %
The Arkansas Power 3 Light Cenpany has requested that Technical Specification 3.6.l.4 te changed by lowering the minimun initial containment temperature and pressure to 50 degrees Fahrenheit and a negative 3.0 pounds per square inch gauge. The limitinq conditions for maximum initial coitainment tegerature and pressure have not changed. The lower limits of temperature and pressure are based on a external differential pressure of a negative 5.0 pounds per square inch gauge.
(2) The current Technical Specifications, Table 2.2-1, Item 3, " Reactor Protective Instrumentation Trip Setpoint Limits, "and Table 3.3.4, Item 8(b)", Engineered Safety Features Actuation System Instrumentation Trip Values", define a steam generator low water level trip setpoint of greater than or equal to 49.0 percent. The Arkansas Power & Light Company has proposed changing the existing steam generator low water level trip setpoint from greater than or equal to 49.0 percent to greater than or equal to 46.5 percent.
(3) In Amendment No. I to License NPF-6, issued on September 1,1978, exemptions to Appendix A Technical Specifications were stipulated in Paragraph II of Section 2.C.(2). Paragraph II states:
"The licensee shall be exempted from conpliance with the following Appendix A Technical Specification related to conducting the steam generator feed. vater system waterhammer testing during the initial startup and power ascension testing program. The value of the steam generator low water level trip setpoint in Item 8(b) of Technical Specification Table 3.3-4 may be reduced, during this testing only, from a value of greater than or equal to 49.4 percent to greater than or equal to 10.0 percent. The licensee shall be exempted f rom compliance with Appendix A Technical Specification 3.3.3.6 for the Containment Radiation Monitors during Mode 3 operations".
EVALUATION (1) Two concerns that arise from lowering the limiting conditions for operation are the external containment pressure resulting from an
. inadvertent actuation of the containment spray system and the minimum containment back pressure for use in the Emergency Core Cooling System performance evaluation.
The Arkansas Power & Light Company has analyzed the contain.aent structural design for an external pressure of a negative 5.0 pounds per square inch gauge. We have concluded that the structural analysis of the containment for this external pressure is acceptable.
We have completed a bounding confirmatory analysis of the maximum external pressure that would result from the inadvertent actuation of the containment spray system and have calculated a differential pressure of a negative 4.8 pounds per square inch gauge, confirming that the value used by the Arkansas Power & Light Company is conservative.
We have also performed a confirmatory analysis using the CONTEMPT LT/026 computer code to verify that the minimum containment back-pressure used in the Arkansas Nuclear One, Unit 2 Emergency Core Cooling System performance evaluation is still valid.
Based on our bounding and confirmatory analyses as stated above, we find the proposed change by Arkansas Power & Light Company to be acceptable. Therefore, the use of a minimum initial containment temperature of 50 degrees Fahrenheit and an initial containment pressure of a negative 3.0 pounds per square inch gauge for Technical Specification 3.6.1.4 is hereby approved.
(2 ) The setpoint for the steam generator low water level trip setpoint, as originally determined, was 45 percent.
This setpoint plus the error band of 4.4 percent associated with the original Fisher &
Porter transmitters used in measuring the setpoint, yielded a mini-mun steam generator low water trip setpoint of greater than or equal to 49.4 percent.
The 4.4 percent margin-error was determined from environmental qualification testing associated with the Fisher &
Porter transmitters.
. The Arkansas Power & Light Company has informeu us that the Fisher a Porter transmitters have been repla<.ed with Rosemont transmitters.
The Rosemont transmitters have now bien environmentally qualified ar.d it has been determined that the Resecont Transmitter error associated with the steam generator low water level setpoint is smaller than those originally determic.ed for the Fisher & Porter transmitters.
The error band associated with the new environmentally qualifed Rosemont transmitters has been determined to be 1.5 percent which when added to the steam generator low water level setpoint of 4S percent yields a new proposed value of greater than or equal to 46.5 percent.
We find this change to be acceptable based on our determination that the original setpoint of 45 percent has not changed and that the new error band of 1.5 percent for the Rosemont transmitters has been determined by testing and environmental qualification.
Therefore, the use of a limiting steam generator low water level trip setpoint of greater than or equal to 46.5 percent is hereby approved for use in Technical Specification Table 2.2-1, Item 8; and Table 3.3.4, Item 8(b).
(3 ) As stated in Item (2) above, we have approved a change in the steam generator low water level trip setpoint, Item 8(b), Technical Specification Table 3.3-4.
This value, as stated above, has been changed from greater than or equal to 49.4 percent to greater than or equal to 46.5 percent. Therefore, the appropriate sentence of Paragraph 2, Section 2.C(2) is hereby amended to read, "The value of the steam generator low water level trip setpoint in Item 8(b) of Technical Specification Table 3.3-4 may be reduced during this testing only, from a value of greater than or equal to 46.5 percent to greater than or equal to 10.0 percent". Also, the last sentence of Paragraph II of Section 2.C(2) is hereby removed based on our Safety Evaluation supporting Amendment No. ' to License NFF-6 issued on December 1,1978.
ENVIRONMENTAL CONSIDERATION We have de* ermined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 551.5(d)(4), that an environmental inpact and/or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
5-Conclusion We have concluded, based on the considerations discussed above that (1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered or a significant decrease in any safety margin, it does not involve a sig-nificant 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 (3) such activities will be conducted in compliance with the Cocinission's regulations and the issuance of this amendment will not be inimical to the cocron defense and security or to the health and safety of the public.
i k.t e,
Leon B. Engl[, Project Manager Light Water Reactors Branch No. 1 Division of Project Management 0
(,.
7 John F. Stolz, Chief d
,Lfght Water Reactors Branch No. 1 Division of Project Management DATED: MAR 191979