ML20082J265
| ML20082J265 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/10/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20082J253 | List: |
| References | |
| NUDOCS 8312020056 | |
| Download: ML20082J265 (5) | |
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SAFETY EVALUATION AMENDMENT NO. 7 TO DPR-76 DIABLO CANYON NUCLEAR POWER PLANT, UNIT 1 DOCKET N0. 50-275 Introduction By letter dated December 29, 1982, as supplemented by letter dated September 12, 1983, the Pacific Gas & Electric Company (PG&E, the licensee) proposed changes to the Diablo Canyon Nuclear Power Plant Appendix A Technical Specifications. These proposed changes will allow the installation of two new 7.5 KVA inverters and their associated busses which are necessary to increase the capacity of the class IE instrument AC System from 30 KVA to 45 KVA to accommodate loads associated with NUREG-0737 requirements.
By letter dated Mae 2,1983, PG&E ~ proposed additional changes to Table 3.6-1 of the technical specifications for Diablo Canyon. These changes reflect proposed containment isolation system modifications, and entail adding several valves to the table, deleting others, and revising the footnoting in the table.
In a letter dated May 23, 1983, PG&E proposed changes to the technical specifications concerning fire suppression systems at Diablo Canyon. A requirement for an additional fire water pump is being added to the operability reouiremex and the requirements for replacement of Halon system initiators has been revised to specify an achievable initiator replacement program.
By letters dated June 23, and July 24, 1983, PG&E proposed still other changes to the technical specifications for their Diablo Canyon plant. These proposed changes would change the time requirements for containment spray initiation.
Evaluation New Inverters and Associated Busses The licensee is installing two new vital AC busses with their associated inverters. The proposed change. increases the capacity of the Class IE instrument AC system from 30 to 45 KVA, and was necessitated.to accommodate loads associated with THI (NUREG-0737) requirements.
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The supplemental inverter and associated bus loading configuration is such that equipment assigned to these busses is not required for ECCS actuation or safe shutdown.
These changes do not alter the fundamental design of the system. Each inverter is independently connected to its respective instrument distribution panel so that loss of an inverter cannot affect more than one distribution panel. The inverters operate normally on both the 480 VAC and 125 VDC systems.
If either system is interrupted, the inverters will be supplied from the remaining source without interruption. With the additional DC inverter loads on the existing batteries, the capacity is such that at least a two hour station blackout margin exists as provided in the previcus design.
In addition, a single 120 VAC backup power source can be switched to any one of the vital busses. Each distribution panel can receive power from the 120 VAC backup source under operator control. The transfer breakers are mechanically inter-locked to prevent paralleling the inverters with the backup power source.
Therefore no single failure in the instrumentation and control power supply systen or its associated power supplies can cause a loss of power to more than one of the redundant load groups.
The staff concludes that the proposed modification and associated technical specification changes meet the requirements of Criteria 17 and 18 of Appendix A to 10 CFR 50 and are, therefore, acceptable.
Containment Isolation System The licensee is installing a Post Accident Sanpling System, requiring the installation of six containment isolation valves (FCV-696 through FCV-700 and a check valve in series with FCV-700). Another valve (RCS-1-512D) has been identified which should be subjected to local leak rate testing, in accordance with Appendix J to 10 CFR Part 50. The staff considers the addition of these valves to Table 3.6-1 to be appropriate and acceptable.
Two valves are being deleted from Table 3.6-1, namely, valve FCV-682 and a series check valve. These valves were in a line identified as the
" Instrument Air Supply for H,, Purge." Plant modifications (such as the installation of hydrogen recbmbiners) have made this penetration unnecessary, and it will be closed with caps welded onto the pipe penetration. Thus, deletion of those two valves from Table 3.6-1 is appropriate and acceptable.
The first footnote at the end of Table 3.6-1 currently reads:
"*May be opened on an intermittent basis under adminstrative control (No.'mally closed manual valves only)".
Valves marked by an asterisk (*) in the table are normally closed, but may be opened intermittently during normal plant operation for such purposes as drawing samples through sample lines. The licensee purposes to revise the parenthetical e))ression in the footnote to read: ".....tNormally closed manual or remotely operable valves only)". Allowing remotely operable valves to be opened internittently is equally as acceptable as allowing nanual valves to be opened, since both require administrative control for their repositioning and rerntely operable valves can be closed from the control room.
Thus, the revision of the footnote is acceptable.
. The licensee proposed to add an asterisk to 13 valves in Table 3.6-1, making them subject to the footnote discussed above. These 13 valves are FCV-696 through FCV-700, FCV-235 through FCV-240, SI-1-161, and RCS-1-5120. This is necessary to allow periodic testing and operation of the associated equipment (primarily sampling systems). The staff finds this to be acceptable.
A second footnote in Table 3.6-1 reads:
"* Note subject to Type C leakage tests." The licensee proposed to remove the footnoting symbol (#) from three check valves in the lines identified as the "CCW Supply to RCP 10",
"CCW return from RCP (FCV-749 Bypass) 1C", and "CCW Supply to Excess Letdown Heat Exchanger 0C."
This would mean the check valves would be added to the Type C local leak testing program reonired by Appendix J to 10 CFR Part 50.
This change, therefore, is acceptable.
In conclusion, the staff finds all of the proposed changes to Table 3.6-1 of the Technical Specifications to be acceptable.
Fire Suppression System Section 3.7.9.1 of the Technical Specifications previously required at least one operable high pressure pump. However, the licensee identified the need for a greater quantity of water to supply anticipated fire fighting requirements. Therefore, one pump may not be able to meet this need, depend-ing on the demand from manual hose streams and automatic fire suppression systems. Consequently, the limiting condition for operation will be changed to require that two high pressure pumps be operable. We conclude that this change will provide greater assurance that the required quantity of water for fire fighting will be available and, therefore, is acceptable.
Section 4.7.9.4 of the technical specifications previously required that explosive initiators in the Halon system be replaced at least once per 5 years with initiators that have a remaining service life of at least 5 years.
However, the maximum service life of all initiators is 5 years from the date of manufacture. Therefore, considering storage, shipping and other normal time delays, it is not possible to literally comply with this surveillance requirement. The intent of this requirement is to assure that initiators are not being used beyond their service life. The licensee's proposed modification will stipulate that initiators are replaced prior to expiration of the service life and is, therefore, acceptable.
Containment Spray Initiation The licensee has proposed certain changes to the technical specifications concerning the initiation of containment spray. These proposed changes would reflect an increase in the delay time for containment spray initiation from 40 to 75 seconds. The delay time is the elapsed time from the receipt of a containment high-high pressure signal (which activates the containment spray system), to the delivery of spray to the containment.
. To support the proposed changes to the Technical Specifications, the licensee provided'a reanalysis of the containment pressure and tenperature response to the design basis LOCA; i.e. a double-ended break of the reactor coolant pump suction (cold leg) piping. The licensee's reanalysis, using the Westinghouse C0C0 Code, shows that the peak containment pressure does not exceed the containment design pressure (47 psig). For the analysis, the licensee increased the containment spray system delay time to 60 seconds, to provide a 5 second margin relative to the proposed changes to the Technical Specifications. Also, the licensee used new data for the mass and energy of water and steam released from the pipe break. The method used by the licensee to compute the mass and energy release rate data is documented in Westinghouse Topical Report WCAP-8312-A, " Westinghouse Mass and Energy Release Data for Containment Design." This topical report was approved by the staff in a letter dated March 12, 1975; therefore, the licensee's mass and energy release rate data for the double-ended pump suction break are acceptable.
The staff reviewed the remaining plant parameters used in the LOCA reanalysis and found them to be conservative for calculating peak containment pressure, except for the containment spray flow rate. The FSAR design value flow rate for one spray train is 2600 gpm; the licensee used a flow rate of 3250 gpm, a value obtained from plant preoperational tests. The licensee calculated a peak containment pressure of 46.91 psig using the 3250 gpm flow rate (only one of two redundant spray trains assumed operable). The staff performed a confirmatory analysis using its CONTEMPT-LT/28 computer code and, assumitig the more conservative spray flow rate (2600 gpm), a peak calculated containment pressure of 45.4 psig was obtained. Additional staff analysis shows that the calculation is relatively insensitive to the spray flow rate, i.e., a 3250 gpm spray flow reduces the peak pressure by only 0.1 psig when compared to the pressure obtained when assuming a 2600 gpm spray flow.
Based upon the staff's confirmatory analysis, which also shows that the containment design pressure would not be exceeded for a spray system delay time of 80 seconds, the proposed changes to the Technical Specifications are found to be acceptable. The pr7 posed changes appear in Table 4.8-2, " Load Sequencing Timers, ESF Timers," where a maximum timer setting of 28 seconds is specified for the containment spray pumps, and Table 3.3-5, " Engineered Safety Features Response Times," where the containment spray response time is increased from "
27.5" to "
48.5" seconds. A footnote to the response time explains that the time interval is from when containment pressure exceeds the high-high setpoint until the spray pump is started and the discharge valve is fully open, assumir;g offsite power is not available. The proposed values are consistent with an overall spray system delay time of 75 seconds.
The FSAR value of the two-hour thyroid dose at the site boundary was previously calculated to be 95.9 REM for the case of no post-LOCA delay in the containment spray. The licensee has reanalyzed the above value and the value for the proposed delay in containment spray using a current verified code and dose conversion factors provided in Revision 1 to Regulatory Guide 1.109. The results of the reanalysis indicated that two-hour thyroid dose at the site would be 85.6 REM for no spray delay and 93.4 REM for the proposed delay.
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l The licensee also proposes to revise the basis for Technical Specification 3/4.6.1.4, Containment Systems Internal Pressure, to reflect the reanalysis of the design basis LOCA. The proposed revision has been found acceptable.
While there is a small reduction in the safety margin in both containment pressure and dose consideration on the basis of the analysis using the revised code, they are clearly within acceptable criteria, i.e. the design of the containment, 47 psig, and the 300 REM value in 10 CFR 100. Thereforc, the staff concludes that, based on the foregoing discussions, the proposed changes to the Technical Specifications are acceptable.
l Contact With State Official I
By copy of letters dated July 15, August 11, August 12 and August 25, 1983 to the licensee, the NRC staff advised the Chief 'of the Radiological Health Branch, State Department of Health Services, State of California, of its proposed determination of no significant hazards consideration. No comments were received.
Environmental Consideratinn We have determined that this amendment does not authorize a change in effluent types or total amount nor an increase in power level and will not result in any significant environmental impact. Having made this determination, re have further concluded that this amendment involves action which is insignificant 4
i from the standpoint of environmental impact and pursuant 10 CFR Section 51.5(d)
(4), that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
Conclusion Based upon our evaluation of the proposed changes to the Diablo Canyon Nuclear Power Plant, Unit 1 Technical Specifications, we have concluded that:
there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and i
security or to the health and safety of the public. We, therefore, conclude that the proposed changes are acceptable.
l Dated:
NOV 101983 1
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November 10, 1983 ISSUANCE OF AMENDMENT NO. 7 TO FACILITY OPERATING LICENSE NO. DPR-76 DIABLO CANYON NUCLEAR POWER PLANT, UNIT 1 DISTRIBUTION:
Document Control 50-275 NRC PDR L PDR NSIC PRC System LB#3 Reading JLee HSchierling BBuckley LChandler, OELD HRDenton DEisenhut/RPurple TMNovak JRutberg, OELD AToalston, AIG ELJordan, IE JMTaylor, IE LJHarmon, IE (2)
JSauder WMiller IDinitz WJones, OA TBarnhart (4)
BPCotter ARosenthal ACRS (16)
FPagano, IE DBrinkman DHoffman