ML19225B403
| ML19225B403 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 06/15/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19225B401 | List: |
| References | |
| SER-790615, NUDOCS 7907250115 | |
| Download: ML19225B403 (4) | |
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SAFETY EVALUATION BY THE OFFICE CF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMt. NOS. 55 AND 55 TO FACILITY LICENSE NOS. OPR PHILADELPHIA ELECTRIC COMPANY PUBLIC SERVITELECTRIC AND GAS C0fiPANY_
DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY PEACH BOTTOM ATCMIC POWER STATION UNITS NOS. 2 AND 3 DOCKETS NOS. 50-277 AND 50-278 I.
INTRODUCTION 12, 1979 Philadelphia Electric Company (licensee)
By letter dated January requested en amendment to Operating License Nos. DPR-44 and 56 for the Peach The proposed amendment would Bottom Atomic Power Station Unit Nos. 2 and 3.
(1) permit a decrease in the dis-revise the Technical Specifications to:
charge pressure of the High Pressure Service Water (HPSW) pumps from 280 psig to 233 psig; (2) add certain snttt rs to the Table of Safety Related Shock Suppressors, and (3) revise the wording of the Administrative Controls spec-clarify staff requirements for audits of facility activities.
ifications t)
II.
EVALUATION A.
HPSW Pump Discharge Pressure Technical Specification 4.5.B.l(b) for Peach Bottom Units 2 and 3 requires that, af ter pump maintenance and every three months, each HPSW pump be The tested to confim that it delivers 4500 gpm of water at 280 psig.
requested that the HPSW pump pressure be reduced to 233 psig to licenset account for a reduced pressure on the Residual Heat Removal (RHR) side of the RHR heat exchangers by installation of flow restricting orifices and The modification on the RHR drag va' ves upstream of the heat exchangers.
side of the heat exchanger was performed to provide (1) throttling capability in the shutdown cooling mode of operation and (2) additional piping system resistance to prevent pump runout which could occur with one RHR pump Prior to the modification injecting into a broken recirculation loop.I additional resistance was accomplished by throttling the manual heat exchanger outlet valves. With the additSnal resistance, the manusi Because the opertu.ing pressure on the shell side valves can open fully.
of the heat exchanger had been reduced, the licensee proposed to reduce the pressure limit on the tube side in order to maintain the same pressure The reduced pressure on the HPSW system would have the differential.
This reduction advantage of reducing pump wear from river water silt.
in wear would accordingly decrease pump outage for corrective maintenance 41./
155 and increase the overall availability of this safety related component.
NRC Evai 'ation of this modification was transmitted by letter NRC (Lear) to I
PEC0 (Bat ir) dated January 4,1977.
7907259;,5-The 4 HPSW pumps, arranged in two trains of 2 pumps each, supply cooling water to the tube side of the RHR heat exchangers.
Since the shell side of the RHR exchangers contains radioactively contaminated water, any flow resulting from a tube leak should be from the tube to the shell side of the heat exchanger. This design feature is a requirement of the RHR heat exchanger to prevent contamination of the HPSW resulting from tube leaks thereby mini.iizing the potential for significant unmonitored radioactive releases.
The licensee performed an analysis of RHR and HPSW pressures similar to that p~'viously reviewed and approved by the staff.2 The maximim pres-sures i. the inlet of the process side of the RHR heat exchanger considered all modes of operation of the RHR/HPSW system except the LPCI mode of operation.
In the LPCI mode cf operation, HPSW is not required for the first ten minutes of operation to mitigate the consequences of an accident,3 Thus in this mode, the pressure on the RHR side of the heat exchanger is higher than on the HPSW side.
Should a tube leak develop during this period of time, potentially contaminated water could leak from the primary system to the service water side of the heat exchanger. However, water would not be discharged in the river because the discharge valve from the heat exchanger is closed.4 Therefore, we conclude that the LPCI mode of operation need not be considereo in the analysis of maximum pressures on the RHR side in order to determine the minimum HPSW discharge pressure.
In RHR mode of operation other than the LPCI mode, if the pressure at the tube outlet is greater than the pressure at the shell inlet of an RHR heat exchanger, no leakage from the shell to the tube side will occur through a tube leak. The shell design provides for the inlet near the botton of the heat exchanger and its outlet near the top; the tubes both enter and exit near the top of the RHR heat exchanger. The maximum pressure on the shell (contaminated water) side inlet was calculated to be 198 psig.
To assure that the HPSW pressure at the heat exchanger outlet is greater than 198 psig, the HPSW pump discharge pressure must be equal to 198 psig plus a pressure differential to account for heat exchanger pressure drop, pipe losses, and elevation differences. The licensee's analysis accounted for accuracy of the instrument measuring the pump discharge pressure and the variation of river water level. We have determined that the cal-culations support a HPSW pump discharge pressure of 233 psig.
The licensee has previously stated that his procedures establish that the HPSW pumps are started before the respective RHR loop is pressurized by the RHR pump, and the HPSW pump is stopped after the RHR pump is shutdown.
Further, the differential pressure is monitored and a antrol room alap is annunciated whenever the differential pressure is less than 15 psi.
2Safety Evaluation supporting Amendments Nos. 5 and 3 to DPR-44 and 56, February 12, 1975.
417 156 PBAPS FSAR, Section 4.8.
Letter, PECO (Hankins) to NRC (Lear), October 8, 19/6.
We conclude from the above that the modifications which have been com-pleted on the RHR system, the analysis of RHR/HPSW discharge pressures, installed instrumentation, and implemented procedures are adequate to preclude significant unmonitored radioactive releases and that a HPSW system discharge pressure of 233 psig is acceptable.
B.
Addition of Safety Related Shock Suppressors The licensee proposed to add certain snubbers to the Table of Safety Related Shock Suppressors to reflect the recent addition of snubbers to the Residual Heat Removal System and to the Reactor Cleanup System of Unit No. 2.
This request is consistent with the current specifications as implemented by Amendment No. 33 to DPR-44, dated April 28, 1977, which states that snubbers may be added to safety related systems without prior approval provided a proposed revision to the Table is included in the next amendment request. Therefore, we find the change to be an admini-strative action which implements a requirement of the existing Technical Specifications.
C.
Administrative Controls The licensee proposed to revise the wording of certain administrative controls specifications by removing the word "all" in sections pertaining to audits. We have reviewed the proposed change and determined that it is more descriptive of an audit function rather than a complete review, is consistent with the language used in the staff's Standard Technical Specifications (NUREG 0123 Rev.1, April 1,1978) and is therefore acceptable.
Environmental Considerations We have determined that the amendments do not authorize a change in effluent types or total amounts nor an increase in pcwer level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of environmental impact and pursuant to 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 these amendments.
Conclusions We have concluded, based on the censiderations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do not 417 157 involve a significant hazards consideration, (2) there is reasonable assur-ance 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 Comission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated: June 15,1979
_n-417 158