ML19209B359
| ML19209B359 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 09/17/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19209B356 | List: |
| References | |
| NUDOCS 7910090563 | |
| Download: ML19209B359 (3) | |
Text
.
p* ** %,
fi
?,,
UNIT 8ED STATES yy p,
NUCLEAR REGULATORY COMMISSION p
WASHING TON,3. C. 20555
%...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NOS. 59 AND 59 TO FACILITY LICENSE NOS. DPR-44 AND DPR-56 PHILADELPHIA ELECTRIC COMPANY PUBLIC SERVICE ELECTRIC AND GAS COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTTC CITY ELECTRIC COMPANY PEACH BOTTOM ATOMIC POWER STATION UNITS NOS. 2 AND 3 00CKETS N05. 50-277 AND 50-278
1.0 INTRODUCTION
By its letter dated August 27, 1979, the Philadelphia Electric Company (PECO) applied for license amendments to change Technical Specification 3.10E from a single,120 hour0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> (five day) delay time prior to moving fuel to the spent fuel pool to an allowable discharge rate, which could commence as soon as twenty-four hours after the reactor is shut down.
In PEC0's proposal this allowable rate would be detennined for each refueling from a set of graphs, to be included in the Technical Specifications.
PECO calculated the data for these graphs on the basis that the temperature of the water coming out of the spent fuel pool should never exceed 1500F.
even though only two of the three spent fuel cooling loops were operable at the time of the peak heat load.
2.0 SPENT FUEL COOLING The spent fuel pool cooling systems at Peach Bottom consist of three pumps and three heat exchangers in parallel for each of the two reactors.
Each of these three pumps is designed to pump 533 gpm (2.57 x 105 goundsper hour).
Each heat exchanger is designed to transfer 3.75 x 10 BTU /hr froe 0
ll50F fuel pool water to 90 F service water, which is flowing through the heat exchanger at a rate of 4.0 x 10b pounds per hour.
3.0 EVALUATION This Technical Specification and proposed change only pertain to normal refuelings.
It does not affect or change the reactor cooling time when a full core complement of 764 fuel assemblies is transferred to '.he spent fuel pool.
In that case, the fuel pool can be adequately cooled by the Residual Heat Removal System regardless of when the core is transferred.
In the graphs it submitted, PECO allowed for a range in the number of assemblies that may be unloaded in any refueling. The maximum number in this range is 338.
The minimum.eactor cooling time in these graphs is twenty four hours, which is the.ime it normally takes to cool the reactor down.
The maximum fuel assembly discharge cate PECO considered is about 8 fuel assemblies per hour.
From these data we calculated the 3
1ii6 099 7910080
P00R O H E L maximum heat goad for any refueling considered in the groposal to be about 21 x 'O BTV/hr.
If we add to this the 3.3 x 10 BTU /hr which will be generated by 2320 spent fuel assemblies already in the pool, we get a total maximum refueling heat load of 24.3 x 106 BTU /hr. Assuming the conditions given in Section 2.0 Spent Fuel Cooling for this heat load, the temperature of the water coming out of the spent fuel pool would be about 144 F.
If we were to use the measured temperature of the 0
service water in lieu of the design basis 90 F, as suggested in PEC0's submittal, and were to include the heat loss from the surface of the pool, 0
this maximum temperature would be less than 140 F.
Under the guidelines given in NRC Standard Review Plan 9.1.s, 1400F is a pennissible maximum temperature for normal operation of the spent fuel pool cooling system.
In the event that one of the three loops were to fail at this peak load, we calculate that the temperature of the water coming out of the pool could go up to about 175of in about four hours or so. Because of the low heat flux, the fuel element temperatures would still stay below 1800F, which is far below the 6000F or so at which the fuel elements were in the operating reactor.
Thus one would axpect that none of the fuel elements would be damaged by this gradual increase in temperature up to about 1800F.
If none of the fuel elements are damaged the additional radioactivity that would be released from the site would be insignificant for this temporary, emergency situation. Thus, for the NRC objective of protecting the public health and safety this is an acceptable temperature for this failed condition.
From the above calculations, we find that PECO is in compliance with NRC regulations without adding these graphs to the Peach Bottom 2 and 3 Technical Specifications.
Our review considered the impact of eliminating the fuel decay time on the consequences of a fuel handling accident. Previous reviews assumed that this type event occurs 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after shutdown (SER dated August 11,1972).
As discussed above, it normally takes at least this amount of time to cool the reactor. Thus, it is not possible to remove fuel earlier than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after shutdown. Accordingly, elimination of the restriction on fuel decay time has no impact on the evaluation of the fuel handling accident.
4.0 StM1ARY The present Technical Specification 3.10E, which prohibits moving fuel at the Peach Bottom reactors prior to 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> (5 days) after shutdown, is not necessary to protect the health and safety of the public and may be deleted from the Technical Specifications based on our calculations of maximum heat loads in the fuel storage pool.
5.0 ENVIRONMENTAL CONSIDERATION
We have determined that the amendments do 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
\\\\\\6
\\DC have further concluded that the amendments involve an action which is insig-nificant from the standpoint of environmental impact and, pursuant to 10 CFR B51.5(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.
6.0 CONCLUSION
We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the pro-bability or consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do 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 (3) such activities will be conducted in coinpliance with the Commission's regulations and the issuance of these amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Dated:
September 17, 1979
\\\\\\6 10\\