ML20206J796
| ML20206J796 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 06/16/1986 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML20206J790 | List: |
| References | |
| 1772K, NUDOCS 8606270277 | |
| Download: ML20206J796 (5) | |
Text
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ATTACIWWIT A PROPOSED CHANGE TO APPENDIX A, TECHNICAL SPECIFICATIONS OF FACILITY OPERATING LICENSE NPP-37 REVISED PAGES: NPF-37, page 3/4 5-3 page B 3/4 5-2 8606270277 860616 PDR ADOCK 05000454 P
PDR 1772K
4 EMERGENCY CORE COOLING SYSTEMS 3/4.5.2_ ECCS SUBSYSTEMS - T,yg >, 350 F, LIMITING CONDITION FOR OPERATION 3.5.2 Two independent Emergency Core Cooling System (ECCS) subsystems shall be OPERABLE with each subsystem comprised of:
a.
One OPERABLE centrifugal charging pump, b.
One OPERABLE Safety Injection pump, c.
One OPERABLE RHR heat exchanger, d.
One OPERABLE RHR pump, and An OPERABLE flow path
- capable of taking suction from the refueling e.
water storage tank on a Safety Injection signal and automatic opening of the containment sump suction valves.
APPLICABILITY:
MODES 1, 2, and 3.
ACTION:
With one ECCS subsystem inoperable, restore the inoperable subsystem a.
to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or.be in at least HOT STANOBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
b.
In the event the ECCS is actuated and injects water into the Reactor Coolant System, a Special Report shall be prepared and submitted to the Commission pursuant to Specification 6.9.2 within 90 days describ-ing the circumstances af the actuation and the total accumulated actuation cycles to cate.
The current value of the usage-factor for each affected Safety Injection nozzle shall be provided in this Special Report whenever its value exceeds 0.70.
fand a portion of the discharge paths of bothl RHR pumps may be isolated by closing either SI8809A or SI8809B 3
I
- 0uring MODE 3, tne dischargejpaths of both Safety Injection pumps may'be isolated by closing SI So35ffor a period of up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to perform surveil-lance testing as required by Specification 4.4.6.2.2.
BYRON - UNITS 1 & 2 3/4 5-3
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EMERGENCY CORE COOLING SYSTEMS BASES ECCS SUBSYSTEMS (Continued)
The limitation for a maximum of one centrifugal charging pump to be OPERABLE and the Surveillance Requirement to verify all charging pumps and Safety Injection pumps except the required OPERABLE charging pump to be inoper-able below 330 F provides assurance that a mass addition pressure transient can be relieved by the operation of a single PORV.
The Surveillance Requirements provided to ensure OPERABILITY of each component ensures that at a minimum, the assumptions used in the safety analyses are met and that subsystem OPERABILITY is maintained.
Surveillance Requirements for throttle valve position stops and flow balance testing provide assurance that proper ECCS flows will be maintained in the event of a LOCA.
Maintenance of proper flow resistance and pressure drop in the piping system to each injection point is necessary to:
(1) prevent total pump flow from exceeding runout conditions when the system is in its minimum resistance configuration, (2) provide the proper flow split between injection points in accordance with the assumptions used in the ECCS-LOCA analyses, and (3) provide an acceptable level of total ECCS flow to all injection points equal to or above that assumed in the ECCS-LOCA analyses.
The Surveillance Requirements for leakage testing of ECCS check valves ensures that a failure of one valve will not cause an loc o psic, f k e, intersystem LOCA. In Mod < 3 with Pressurieer pcssure below closed M ) ne.r i 3
accalafors will be. maildle. with +kdr isola & n valves einer-SIE%09 ' valve. is$ ted, 3/4.5.4 REFUELING WATER STORAGE TANK or opcN Meacute a dosed
- 4. pec4,% check valve. leaka3e. M&.
The OPERABILITY of the refueling water storage tank (RWST) as part of the ECCS ensures that a sufficient supply of borated water is available for injection by the ECCS in the event of a LOCA.
The limits on RWST minimum volume and boron concentration ensure that: (1) sufficient water is available within containment to permit recirculation cooling flow to the core, and (2) the reactor will remain subcritical in the cold condition following mixing of the RWST and the RCS water volumes with all control rods inserted except for the most reactive control assembly.
These assumptions are consistent with the LOCA analyses..
The contained water volume limit includes an allowance for water not usable because of tank discharge line location or other physical characteristics.
A minimum contained borated water level of 89% ensures a volume of greater than or equal to 395,000 gallons.
The limits on contained water volume and boron co'ncentration of the RWST also ensure a pH value of between 8.5 and 11.0 for the solution recirculated within containment after a LOCA.
This pH band minimizes the evolution of iodine and minimizes the effect of chloride and caustic stress corrosion on mechanical systems and components.
BYRON - UNITS 1 & 2 B 3/4 5-2
ATTAQ95NT B SIGNIFICANT HAZARDS CONSIDERATIONS Commonwealth Edison has evaluated this proposed amendment and determined that it involves no significant hazards considerations.
According to 10 CFR 50.92(c), a proposed amendment to an operating license involves no significant hazards considerations if operation of the facility in accordance with the proposed amendment would not:
(1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) Involve a significant reduction in a margin of safety.
The proposed amendment allows a SI8809 valve to be closed concurrently with valve SI8835 while performing reactor coolant system pressure isolation check valve leak testing. This can only be done in Mode 3 and the valves will not be closed longer than two hours.
In addition, the safety injection accumulators will be available with their isolation valves either closed, but energized, or open.
The probability of an accident is not affected by closure of two valves in the safety injection system during surveillance testing.
The previously evaluated accident that is potentially affected by the proposed amendment is a loss-of-coolant accident (LOCA). The Technical Specifications currently allow the SI8835 valve, located in the common discharge path of both safety injection pumps, to be closed in Mode 3 for a period of up to two hours to perform the check valve leakage surveillance.
To perform this surveillance on one set of check valves, a SI8809 valve must be closed in conjunction with the SI8835 valve.
In this situation, if a LOCA occurred, ECCS flow would be available from at least one centrifugal charging pump and one residual heat removal pump injecting into two reactor coolant system cold legs. Normally, the safety injection accumulators are not required to be operable in Mode 3 below 1000 psig. However, when performing this surveillance in Mode 3 below 1000 psig, the safety injection accumulators will be available with their isolation valves either closed'and energized, or open. In this condition, the accumulator isolation valves will open automatically on a safety injection signal if the containment pressure high-1 setpoint is exceeded. Based on detailed Westinghouse calculations on a similar plant, it is expected that the 3.4 psig containment high-1 setpoint for Byron would be exceeded during a LOCA in Mode 3 operation.
Westinghouse's evaluation of this scenario for Byron has concluded that the
1 i maximum peak clad temperature (PCT) for the worst case LOCA in Mode 3 would be significantly less than the current 2110'F value for PCT calculated in the PSAR at full power operating conditions. Based on the information presented above, the consequences of an accident previously evaluated are not increased.
This proposed amendment only involves the temporary closure of two valves in the safety injection system during reactor coolant system pressure isolation check valve leakage testing. As a result, it does not create the possibility of a new or different kind of accident from any accident previously evaluated.
Rather than involving a reduction in a margin of safety, this proposed amendment can result in an overall increase in the margin of safety for Byron. This is accomplished by offsetting the insignificant reduction in delivered ECCS flow during a LOCA in Mode 3 with the increased assurance of the integrity of the reactor coolant system pressure isolation check valves. As a result, the probability of an intersystem LOCA initiated by the failure of these check valves is reduced.
Based on the preceeding assessment, Commonwealth Edison believes this proposed amendment involves no significant hazards considerations.
1772K