ML20141K893
| ML20141K893 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 05/23/1997 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML20141K891 | List: |
| References | |
| NUDOCS 9706020061 | |
| Download: ML20141K893 (8) | |
Text
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M LT-EESENCY CORE COOLING SYST9tS 1
! SURVEILLAur0 REOUIRDENTS 4.5.2 Each ECCS subsystem shall be demonstrated OPERABLE:
- a. At least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by verifying that the following valves are in the indicated positions with power to the valve operators
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7 Valve
- Number Valve Function Valve Position '
i IWV SI8806 Section to the SI Open j Pumps l IWV S!8835 SI Pump Discharge Open*
i To RCS Cold Legs MDV S18813 SI Pump Recirculation Open
, To The RWST l NDV SI8809A RIE Pup Discharge to Open*
l RCS Cold Legs l IOV $188098 RNR Pump Discharge to Open*
j RCS Cold Legs
j DOV SI8802A SI Pump Discharge to Closed j RCS Hot Legs 4
h M b Mh G} cat Ho j b.
- 1 east once per days by: "[gg g j j 1) Venting ump ngs ping hi outside of containment and gge,ger
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- 2) Verifying that each valve (manual, power-operated, or automa e i in the flow path that is not locked, sealed, o * -- i .r m secured in position, is in its correct positio O '
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- c. By a visual inspection which verifies that no loose (ap\sccbc h{ra"gs, D@W j trash, clothing, etc.) is present in the containment which couir 1- trans rted to the containment sump and cause restriction of the This visual etion shall
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g\n ~gg o+4 n m% 2 3 r t n t u M "yalves,anyArnaligSirTor-testing pursuant to Specification 4.4.6.2.2.
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1 i BEMDCY CORE COOL 215 SYSTDes l
- SURVEILLANCE REIUIRBENTS 4.5.2 Each ECCS subsystem shall be demonstrated OPERABLE:
l s a. At least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by verifying that the following valves j are in the indicated positions with power to the valve operstars 1 renewed:
) Walse* Number Valve Function Valve Position W sIaees section to the SI Open ,
j Pu e s i i NOV sIsass sI Pup Dischavipe opena j To RCS Cold Lags l W Slas13 51 Pimp Reciresistion open 1 To The Ed5T e .
- W $18009B NE Pump Discharge to Open*
, - RCS Hot Lags
', W SI8002S SI Pisup Discherpe to Closed j RCS Hot Lags j
k At least once per si days by:
- 1) Venting the ECCS pimip casings and discherpe piping high points autside of containment, and 6
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- 2) Verifying that each valve (manual, power-operstad, or automatic)
{ in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position.
4 i c. By a visual inspection which verifies that no loose debris (rags,
{ trash, clothing, etc.) is present in the containment which could be 4 transported to the containment susp and cause restriction of the pump suctions during LOCA conditions. This visual inspection shall j be perfomed: ._
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! " Valves may be realigned for testing pursuant to Specification 4.4.6.2.2. '
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l EMERGENCY CORE COOLING SYSTEMS i
1 BASES
- l ECCS SUBSYSTEMS (Continued) l The limitation for a maximum of one centrifugal charging pump to be OPERABLE and the Surveillance Requirement to verify all charging pumps except '
the required OPERABLE Charging pump to be inoperable in MODE 4 with one or )
more of the RCS cold legs less than or equal to 330*F, MODE 5, and MODE 6 with ;
the reactor vessel head on, provides assurance that a mase addition pressure transient can be relieved by the operation of a single PORV or RHR suction s j relief valve. Similarly, the requirement to verify all Safety Injection pumps ) ;
are inoperable in MODE 4 with the temperature of one or more of the RCS Cold / -
Legs less than or equal to 330*F, in MODE 5 with pressurizer level greater than \
5 percent (Level 409.5') and in MODE 6 with pressurizer level greater than 5 percent and the reactor vessel head resting on the reactor vessel flange, y
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provides assurance that a mass addition pressure transient can be relieved by \
a single PORV or RHR suction relief valve.
In MODE 5 and MODE 6 with pressurizer level less than or equal to 5 percent, (
' at least one Safety Injection pump or gravity feed from the RWST must be avail- )
able to mitigate the effects of a loss of decay heat removal during partially ,
drained conditions. Surveillance requirements assure availability, but prevent )
inadvertent actuation during these modes. . The desired flow path for the SI /
pump or gravity feed varies with RCS configuration and is, therefore, procedurally; addressed.
The Surveillance Requirements define what constitutes an adequate hot side (
vent for various plant conditions. It was determined that removing the reactor )
vessel head was an adequate vent under all conditions. Other venting alterna-tives have restrictions based on time from shutdown and RCS temperature. The
( i values in the surveillance were taken from the graph on the following page. /
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 ,
nf ECCS check valves ensures that a failure of one valve will not cause an intersystem LOCA. In Mode 3, with pressurizer pressure below 1000 psig, the accumulators will be available with their isolation valves either closed but :
energized, or open, whenever a SI8809 valve is closed to perform check valve e tasting. [
-.1hQT27 k BRAIDWOOD - UNITS 1 & 2 B 3/4 5-2 Amendment No.
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, 9 INSERT A For Unit 1, Surveillance Requirement 4.5.2.b.1 requires that the ECCS pump casings and j discharge piping high points equipped with vent valves be vented on a 31 day frequency. This venting surveillance does not apply to subsystems in communication with operating systems l
because the flows and/or pressures prevalent in these systems are suflicient to provide confidence that water hammer which occur from voiding would not result in unacceptable dynamic loads.
During normal operation, this exclusion would e.pply to the High Head Safety Injection subsystem. During shutdown cooling operation, the exclusion would apply to the single required Centrifugal Charging pump and operating RH pump, in addition to the ECCS piping in communication with the operating pumps. Because the centrifugal charging pumps are not ;
equipped with pump casing vent valves, and the pump design and system piping configuration allow the pumps to be maintained under positive pressure when in standby, manual venting of these pumps is not required.
The sutveillance requirement to ultrasonically examine selected portions of piping involves the idle CV pump discharge piping up to the first check valve on the pump discharge and miniflow lines, and the stagnant portion of the piping upstream of the ISI8801 A/B adjacent to the vent I valve ISIO45. This will provide added assurance that the piping is water solid.
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ATTACilMENT C EVALUATION OF SIGNIFICANT HAZARDS CONSIDERATIONS FOR PROPOSED CHANGES TO APPENDIX A :
TECHNICAL SPECIFICATIONS OF FACILITY OPERATING LICENSE NPF-72 i
i Commonwealth Edison has evaluated this proposed amendment and determined that it involves no significant hazards considerations. According to Title 10 Code of Federal Regulations Section 50 Subsection 92 Paragraph c (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 eccident previously evaluated; or i 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. I A. INTRODUCTION Commonwealth Edison (Comed) proposes to revise Braidwood Technical Specification (TS) 4.5.2.b.1 and associated bases as it relates to the requirement to vent the Emergency Core Cooling Systems (ECCS) pump casings and discharge piping high points. The change will revise the venting requirement to encompass the non-operating ECCS pumps and discharge piping which are provided with high point vent valves Those portions of the ECCS systems which are in communication with operating system pressure and/or flow would not be required to be vented.
This would normally encompass the High Head Safety injection (CV) subsystem during Modes 1-4 operation, and the Low Head Safety injection Subsystem (RH) during periods when shutdown cooling is in operation. Additionally, the wording of the surveillance will be revised to clearly indicate that the installed high point vent valves and pump casing vent valves will be utilized to accomplish the venting operation The Intermediate Head Safety injection (SI) subsystem and the RH subsystem are equipped with pump casing vents. The centrifugal CV pumps are not equipped with pump casing vent valves due to the configuration of the suction and discharge piping. Both the suction and discharge piping enter the pump casing from the top, so the pumps are essentially self-venting. Finally, a new requirement is added to ultrasonically examine the discharge piping of the idle centrifugal charging pump and the portion 8
( of the piping upstream of the High Head Safety injection isolation valves (1S18801 A&B) adjacent to the vent valve ISIO45 on a monthly basis. These changes are required to align the surveillance requirement with the physical constmetion of the installed piping, and accommodate operating conditions which preclude cycling of the installed high point vent valve during system operation.
1 B. NO SIGNIFICANT llAZARDS ANALYSIS 1.
The proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
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' The proposed changes will align the surveillance requirements with the installed system design and normal operating conditions. No increase in the probability of an accident will occur as a result of this change. The conduct of surveillances required by the Technical Specifications is not postulated to initiate an accident. The level of surveillance performed to date has provided confidence that the objective of the current surveillance requirement has been met. As such, the proposed change does not result in a significant increase in the probability of occurrence of a previously analyzed accident.
The consequences of a previously analyzed accident are not increased. Operating experience has shown that the level of surveillance performed to date is suflicient to provide confidence that no significant voiding has occurred in the affected piping.
Ultrasonic examinations have confirmed the water solid condition of the piping. Although voiding ls not expected, evaluation ofpostulated voided conditions confirm that unaccepte.ble dynamic loading would not occur, and, therefore, the integrity of the ECCS piping is not compromised Thus, the ECCS will be capable of performing its design function of cooling the reactor core and providing shutdown capability following initiation of the cevain accidents. This will ensure that the consequences of a previously analyzed accident are not significantly increased.
Therefore, these proposed revisions do not result in a significant increase in the probability or consequences of an accident previously analyzed.
- 2. The proposed change does not create the possibility of a new or difTerent kind of accident from any accident previously evaluated.
The proposed changes do not create the possibility of a new or different kind of accident.
Comed has evaluated the piping configuration for the ECCS discharge piping of the ECCS subsystems. A specific engineering evaluation ofboth a voided 2-inch and 8-inch RH line was performed. This evaluation concluded that the piping can withstand the dynamic loads caused by the maximum credible air void. Due to the higher-pressure l rating and smaller size of the Si and CV discharge piping, this evaluation is considered bounding for the ECCS subsystems. The results of the evaluation were submitted for staff 1
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.e review in a letter dated March 12,1990, in support of Amendment 36 to the Operating Licenses for Braidwood. The proposed changes will not result in new failure modes because no new equipment is installed, and installed equipment is not operated in a new or !
different manner. Manual venting operations have been performed as permitted by system )
operation and piping configuration. This venting surveillance does not apply to subsystems in communication with operating systems because the flows and/or pressures prevalent in these systems are suflicient to provide confidence that water hammer which could occur from voiding would not result in unacceptable dynamic loads. Accordingly, this change l will not create the possibility of a new or different kind of accident.
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l The proposed change does not involve a significant reduction in a margin of safety.
The margin of safety is not significantly reduced because the proposed change will provide l
1 suflicient assurance that excessive voiding will not occur. This will assure proper system functioning. Venting of the idle subsystems, in conjunction with the operating conditions of the subsystems in operation, provides confidence that voiding is not present. This has been confirmed by the performance ofultrasonic examinations of the piping ofinterest.
This meets the objective of the surveillance requirement and thus preserves the margin of safety.
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Therefore, based on the above evaluation, Comed has concluded that these changes involve no I significant hazards considerations.
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4 ATTACilMENT D ENVIRONMENTAL ASSESSMENT FOR PROPOSED CHANGES TO APPENDIX A TECHNICAL SPECIFICATIONS OF FACILITY OPERATING LICENSE NPF-72 Commonwealth Edison Company (Comed) has evaluated this proposed license amendment request against the criteria for identification of ficensing and regulatory actions requiring environmental assessment in accordance with Title 10, Code of Federal Regulations, Part 51, Section 21 (10 CFR 51.21). Comed has determined that this proposed license amendment request meets the criteria for a categorical exclusion set forth in 10 CFR 51.22(c)(9). This determination is based upon the following:
- 1. The proposed licensing action involves the issuance of an amendment to a license for a reactor pursuant to 10 CFR 50 which changes a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20 or which changes an inspection or a surveillance requirement;
- 2. this proposed license amendment request involves no significant hazards considerations;
- 3. there is no significant change in the types or significant increase in the amounts of ,
any efiluent that may be released offsite; and i
- 4. there is no significant increase in individual or cumulative occupational radiation j exposure.
l Therefore, pursuant to 10 CFR 5122(b), neither an environmental impact statement nor an environmental assessment is necessary for this proposed license amendment request.
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