ML18058B026
| ML18058B026 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 08/24/1992 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML18058B024 | List: |
| References | |
| NUDOCS 9209020187 | |
| Download: ML18058B026 (7) | |
Text
ENCLOSURE I Consumers Power Company Palisades Plant Docket 50-255 SHUTDOWN COOLING TECHNICAL SPECIFICATIONS CHANGE REQUEST Revised Technical Specification Change Pages August 24, 1992 6 Pages
3.1.9 SHUTDOWN COOLING
- Specification 3.1.9.1 One PCS -0r SDC loop shall be in operation providing ~2810 gpm flow through the reactor core, and at least two of the means of decay heat removal listed below shall be OPERABLE:
- 1. SDC loop A consisting of an OPERABLE SDC pump and an OPERABLE heat flow path to Lake Michigan.
- 2. SDC loop B consisting of an OPERABLE SDC pump and an OPERABLE heat flow path to Lake Michigan.
- 3. PCS loop 1 consisting of an OPERABLE Primary Coolant Pump and an OPERABLE Steam Generator and secondary water level ~-84%.
- 4. PCS loop 2 consisting of an OPERABLE Primary Coolant Pump and an OPERABLE Steam Generator and secondary water level ~-84%.
Applicability Specification 3.1.9.1 applies when there is fuel in the reactor, with PCS Temperature is >200°F and ~300°F.
Exception
- 1. All flow through the reactor core may be intentionally stopped for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> provided:
- b. Core outlet temperature stays ~l0°F below saturation temperature.
Action
- 1. With fewer OPERABLE means of decay heat removal than required:
- a. Immediately initiate corrective action to return a second loop to OPERABLE status, and
- b. Matntain PCS temperature as low as practical with available equipment.
- c. If a SDC loop is available, be <200°F within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
- 2. With less flow through the core than required:
- b. Immediately initiate corrective action to return a loop to operation providing flow through the core.
25d Amendment No.
3.1.9 SHUTDOWN COOLING
. Specification
- 3.1.9.2 One SOC loop shall be in operation providing ~2810 gpm flow through the reactor core, and at least two of the means of decay heat removal listed below shall be OPERABLE:
- 1. SOC loop A consisting of an OPERABLE SOC pump and an OPERABLE heat flow path to Lake Michigan.
- 2. SOC loop B consisting of an OPERABLE SOC pump and an OPERABLE heat flow path to Lake Michigan.
- 3. PCS loops 1 and 2, each with an OPERABLE steam generator and secondary level ~-84%.
Applicability Specification 3.1.9.2 applies when there is fuel in the reactor, with PCS Temperature is <200°F and the PCS loops filled.
Exceptions
- 1. All flow through the reactor core may be intentionally stopped for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> provided:
- a. No operations are permitted that would cause reduction of the PCS boron concentration or PCS inventory, and
- b. Core outlet temperature stays ~200°F, and
- 2. One or both SOC loops may be intentionally rendered inoperable for testing or maintenance provided:
. a. One PCS or SOC loop is providing flow through the reactor core, and
- b. Core outlet temperature stays ~200°F, and
- c. Each steam generator secondary water level is ~-84%.
Action
- 1. With* fewer OPERABLE means of decay heat removal than required:
- a. Immediately initiate corrective action to return a second loop to OPERABLE status, and
- b. Maintain PCS temperature as low as practical with available equipment.
- 2. With l~ss flow through the core than required:
- b. Immediately initiate corrective action to return a loop to operation providing flow through the core.
3-25e Amendment No.
. Specification 3.1.9.3 One SOC loop shall be in operation providing ~1000 gpm flow through the reactor core, and at least two of the means of decay heat removal listed below shall be OPERABLE: *
- 1. SOC loop A consisting of an OPERABLE SOC pump and an OPERABLE heat flow path to Lake Michigan.
- 2. SOC loop B consisting of an OPERABLE SOC pump and an OPERABLE heat flow path to Lake Michigan.
App 1i cabil ity Specification 3.1.9.3 applies when there is fuel in the reactor, with PCS Temperature is <200°F and the PCS loops NOT filled.
Exceptions
- 1. All flow through the reactor core may be intentionally stopped for up to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> provided:
- a. No operations are permitted that would cause reduction of the PCS boron concentration or PCS inventory, and
- b. Core outlet temperature stays ~200°F, and
- 2. One or both SOC loops may be intentionally rendered inoperable for testing or maintenance provided:
- a. One SOC loop is providing flow through the reactor core, and
- b. Core outlet temperature stays ~200°F, and
- c. The refueling cavity water level is ~647'.
Action
- 1. With fewer OPERABLE means of decay heat remova 1 than required:
- a. Immediately initiate corrective action to return a second loop to OPERABLE status, and
- b. Maintain PCS temperature as low as practical with available equipment.
- 2. With less flow through the core than required:
- b. Immediately initiate corrective action to return a loop to operation providing flow through the core.
3-25f Amendment No.
- .J .1 .PRIMA~Y COOLANT slEM (PCS) 3.1. g SHUTDOWN COOLING The Shutdown Cooling {SOC) specifications require a minimum flow be maintained through the reactor core and two methods of decay heat removal to be OPERABLE, in each of three situations, PCS temperature 200°F to 300°F, PCS temperature below 200°F with the loops filled, and PCS temperature below 200°F with the loops not filled. "Loops Filled" means the PCS loops are intact, not blocked by dams, and totally filled with coolant.
The requirement to maintain 2810 gpm flow through the reactor core when the PCS loops are filled is based on an analysis of potential dilution events.
Maintenance of this flow assures that indication of increasing count rate will be available to warn the operator and allow compensating action. The requirement to maintain 1000 gpm flow through the reactor core when the loops are not filled assures mixing of the PCS while allowing flow to be reduced to avoid vortexing in the SOC suction piping. The 1000 gpm is based on operating experience, rather on analysis. With flow less than 2810 gpm, Specification 3.10.1 imposes additional requirements for Shutdown Margin and limits charging pump operability. Maintaining flow through the reactor core also allows use of the SOC temperature indication to determine core outlet temperature when the core outlet thermocouples are not i~
service.
Natural circulation is adequate for decay heat removal, however it may not provide adequate mixing of the PCS coolant during PCS boron concentration changes or inadvertent dilution events. Therefore, forced circulation is required except during short intervals when the required loops may be intentionally stopped provided additional constraints are followed.
An OPERABLE steam generator, for the purposes of this specification, must have both its primary and secondary sides intact, its tubes filled with primary coolant, and a secondary water level of at least -84% on the wide range level channels. The specified steam generator secondary water level of -84% ensures that at least one-third of the effective steam generator heat transfer area is covered1 and is therefore sufficient to support natural circulation in the PCS'
- 2 >. In addition, there must be available a method of feedwater addition an~ a controllable path for steam release. **
- A heat flow path to the lake may vary in actual component configuration, method of operation and control, but it shall always accomplish the objective of transferring decay heat from the reactor to Lake Michigan. As a minimum, a heat flow path requires: a shutdown cooling pump, a shutdown cooling heat exchanger, a component cooling water pump, a component cooling heat exchanger, a service water pump, and appropriate piping, valves and controls for the equipment to perform its function. All of this equipment must be OPERABLE and must have adequate, but not necessarily redundant, electrical power.
3-25g Amendment No.
3 *I 3 .1.9
.PR IMA~V COOLANT slEM SHUTDOWN COOLING (PCS)
(Continued)
The shutdown cooling loops at Palisades are not totally independent since they share common suction and discharge piping including valves M0-3015, M0-3016, CV~3006, CV-3025 and CV-3055. Similarly, the Service Water and Component Cooling Water systems are each comprised of two trains which are electrically independent, but not mechanically independent. The arrangement of each of these systems is illustrated in the associated chapters of the FSAR.
Operation of the shutdown cooling loops is limited to when the PCS temperature is below 300°F because, although the original design of the system was for 325°F, the maximum temperature used in the stress analysis of the shutdown cooling system piping was 300°F.
With the PCS temperature >200°F and ~300°F, a single primary coolant loop or a single shutdown cooling loop provides sufficient heat removal capability for removing decay heat. Requiring a second means of decay heat removal to be operable provides an back up in the event of a component failure.
With the PCS temperature ~200°F the SOC loops are the normal means of decay heat removal. If both PCS loops are filled and intact, use of the PCS is permitted as a back up means of decay heat removal to permit maintenance or testing.of SOC components. If a failure of the operating SOC loop required use of the PCS for decay heat removal, temperatures could rise above 200°F but boiling in the steam generators would then provide a method of decay heat removal.
With the PCS temperature ~200°F with the loops not filled, the PCS cannot be used as a method of decay heat removal. Therefore, two SOC loops are required. The loops ar~ considered "not filled" if it has been drained so air has entered the loops and has not yet been removed. Once the PCS loops have been drained to any extent (to install steam generator nozzle dams for **.
example) there could be sufficient air trapped in the steam generator u-tubes to prevent natural circulation.
- The balance of equipment which comprises a heat flow path, (shutdown cooling heat exchanger, component cooling flow path, service water pump, and etc.) must be operated as necessary so as to maintain the PCS temperature and heatup rate within limits. This equipment is manually operated, and has no provision or requirement for automatic actuation during shutdown conditions. During periods when this equipment is required to be OPERABLE, but when PCS temperature and heat load do not require it to be in operation, required components may be temporarily isolated from the cooling flow path in order to perform testing, provided the components themseJ~es are not disabled or.rendered inoperable.
3-25h Amendment No.
~*
~.l PRIMARY COOLANT SYSTEM (PCS) 3.1. 9 SHUTDOWN COOLING (Continued)
An exception to the requirement for continuous circulation through the reactor core i~ provided. £0th SOC and PCS circulation may be stopped for up to one hour provided actions are taken to prevent dilution or draining of the PCS and to avoid situations that could produce steam in the reactor vessel. During periods without forced circulation, admission of water with less Boron concentration than currently in the PCS could collect in a localized pocket and present a potential reactivity addition upon restart of forced circulation. Maintaining the temperature well below boiling ensures that availability of single phase natural circulation. The one hour time limit is not based on analysis. It was chosen to allow testing (such as test closure of containment isolation or shutdown cooling suction valves which require or result in stopping shutdown cooling flow) or minor maintenance, but to restrict the time without mixing and circulation of the PCS.
An exception to the requirement to have heat flow paths to the lake operable has also been provided, when below 200°F. Both heat flow paths may be made inoperable provided that adequate means are provided to assure that decay heat removal is available. In addition, core outlet temperature must be maintained below 200°F, PCS heatup rate must remain within Technical Specification limits, and circulation must be maintained through the reactor core.
In the condition where the PCS loops are filled and both steam generators have sufficient secondary water level, the PCS may be relied upon as the means of decay heat removal allowing maintenance or testing of SOC, Component Cooling or Service water components.
In the condition where the reactor vessel head has been removed and the refueling cavity has been filled for refueling, the mass of water in the pool provides a passive means of decay heat removal. When the cavity is filled to ~647' elevation, this passive heat sink may be relied upon as the means of decay heat removal allowing maintenance or testing of SOC, Component Cooling, or Service water components.
During the exercising of these exceptions, operations which could drain the PCS and thereby cause a loss of, or a failure to regain, shutdown cooling are not allowed. This restriction against reducing PCS inventory does not apply to operations, such as pump flow testing, which may cause relatively minor changes in PCS inventory. The restriction is intended to apply to operations which might actually drain water from the PCS such that inventory could not be quickly regained.
References (1) ABB/CE Letter OPS-91-0496, "Minimum S/G Level Required to Support Natural Circulation Decay Heat Removal."
(2) Consumers Power Company Engineering Analysis EA-GFP-90-03, Revision 0, "Technical Review of ABB/CE Letter OPS-91-046."
3-25i Amendment No.