ML20116J794
| ML20116J794 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 07/31/1996 |
| From: | WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML20116J585 | List:
|
| References | |
| SDF-.1, SDF-0.1, NUDOCS 9608140075 | |
| Download: ML20116J794 (14) | |
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i BACKGROUND INFORMATION FOR AP600 l
SHUTDOWN EMERGENCY RESPONSE GUIDELINES SDF-0.1 AP600 SHUTDOWN SAFETY STATUS TREE DURING SHUTDOWN Rev.2 July 31,1996 WESTINGHOUSE ELECTRIC CORPORATION ENERGY SYSTEMS BUSINESS UNIT ADVANCED TECHNOLOGY BUSINESS AREA P.O. BOX 355 PITI'SBURGH, PENNSYLVANIA 15230 O
Io0**A00ckoIO$oSo3 REVISION: 2 F
TABLE OF CONTENTS Section page
1.0 INTRODUCTION
1-1
2.0 DESCRIPTION
2-1 3.0 DETAILED DESCRIPTION OF STATUS TREE 3-1 3.1 Detailed Description of Status Tree Blocks O
O SDF01403196 ii REVISloN: 2
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1.0 INTRODUCTION
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The Status Tree SDF-0.1, SHUTDOWN SAFETY STATUS TREE, provides a systematic method to
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explicitly determine the status of the plant during shutdown conditions after entering Mode 5. This I
tree requires no operator action other than monitoring a lirnited set of plarit parameters and comparing them to reference values within the tree.
This tree represents the Critical Safety Functions that are of concem during plant shutdown and, as such, is always monitored anytime the plant is in a shutdown condition after entering Mode 5. The tree can direct operators to either of six Shutdown Guidelines (SDGs).
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sDF01073196 l-1 REVislON: 2
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2.0 DESCRIPTION
1 This status tree monitors plant conditions during plant shutdown after entering Mode 5. Prior to this
" shutdown" condition, the plant can be in any state ranging from heatup and pressurization (i.e.,
l from 200 F to no-load temperature) to full power operation. Under any of these conditions (i.e., for I
plant Modes 4 to 1), plant monitoring and response to a reactor trip or requirement for safety l
injection are covered by the Optimal Recovery, Status Trees and Function Restoration Emergency Response Guidelines.
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SDF-0.1, SHUTDOWN SAFETY STATUS TREE is arranged so that the functions are checked in order of importance. Core cooling during shutdown condi ions, is addressed first. During plant I
shutdown conditions the RNS provides core cooling which requires adequate RCS inventory to operate properly. Therefore to ensure core cooling will not be intermpted because of inadequate RCS inventory, and as an early symptom to a loss of shutdown core cooling, RCS inventory checks are made first.
After adequate RCS inventory is checked, RNS operation is checked to ensure shutdown core cooling is being pmvided by RNS. After RNS operation is verified, containment radiation is checked so that an unexpected uncontrolled release will not occur since containment integrity may be breached during plant shutdown maintenance activities. Core reactivity is then checked by monitoring source range flux doubling as an early symptom of an unintended RCS bomn dilution O
which should occur at a slow enough rate to allow appropriate action to be taken to reestablish shutdown margin. RCS cold overpressure symptoms of RCS pressure and temperature are monitored for maintaining the RCS pressure boundary integrity safety function. Lastly RCS temperature change, aside from any nonnal expected RCS temperature change, is used as an early symptom for potential degradation of the core cooling safety function and the RCS pressure boundary integrity safety function.
Since the SHUTDOWN SAFETY STATUS TREE actions are considered important for maintaining the shutdown critical safety functions, they are all assigned an orange priority if the status tree block is not satisfied. 'Ihe SHUTDOWN SAFETY STATUS TREE is considered satisfied when all status j
tree blocks have been satisfied, including the RCS temperature change or controlled heatup or cooldown blocks.
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sDF0140196 2-1 REVIsloN: 2
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r 3.0 DETAILED DESCRIPTION OF STATUS TREE BLOCKS This section provides a very detailed discussion of the Shutdown Status Tree SDF-0.1, SHUTDOWN SAFETY STATUS TREE to facilitate procedure writing and training efforts. By presenting status i
tree background information in greater detail through the use of a structured format (i.e., block description tables), applicability can be more easily determined.
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The block description tables contained in this section are comprised of a one-page (or more) description of each individual decision block on the Status Tree.
- The Block Description Tables for the Status Tree SDF-0.1 SHUTDOWN SAFETY STATUS TREE,
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are presented on the following pages.
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BLOCK DESCRIPTION TABLE FOR SDF-0.13 HLOCK1 BLOCK:
CMT Actuation Signal Blocked PURPOSE:
To detennine if CMT actuation on low pressurizer level is blocked BASIS:
CMT actuation on low pressurizer level can be blocked to permit intentional reduced RCS inventory operations such as during reactor disassembly for refueling. This decision point is used in subsequent blocks for determining appropriate RCS inventory setpoints used to initiate inadequate RCS inventory mitigating actions.
ACTIONS:
Determine if low pressurizer level CMT actuation signal is blocked INSTRUMENTATION:
Pressurizer level CMT actuation signal blocking status indication CONTROL /EOUIPMENT:
N/A KNOWLEDGE:
N/A ADDITIONAL INFORM ATION:
N/A 9
SDF01-073196 3-2 REVisloN: 2
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BLOCK DESCRIPTION TABLE FOR SDF-0.13 BLOCK 2 BLOCK:
PRZR Level Greater Than (SL01) j PURPOSE:
To detennine if pressurizer level is less than the CMT actuation setpoint, SLOl i
BASIS:
Since the pressurizer level PMS and DAS CMT actuation signals are not blocked, indicating that reduced RCS inventory operation is not anticipated. Iow pressurizer level is used for an inadequate RCS inventory symptom to initiate operator action. Therefore, the setpoint for CMT actuation on low pressurizer level is used to determine if the operator should enter SDG-1, RESPONSE TO LOSS OF RCS INVENTORY DURING SHUTDOWN, because of an inadequate RCS inventory conditions.
ACTIONS:
Determine if pressurizer level is greater than SL01 INSTRUhENTATION:
PRZR level indication CONTROL /EOUIPMENT:
N/A KNOWLEDGE:
The opemtor should be aware of manual CMT actuation capability provided by PMS and DAS.
ADDITIONAL INFORMATION:
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SLO 1 - PRZR level CMT actuation setpoint during shutdowT1.
sDF01@3196 3-3 REVislON: 2
BLOCK DESCRIPTION TABLE FOR Fi)F-0.1-3 BLOCK 3 BLOCK:
RCS Hot Leg Level Greater Than (SLO 2)
PURPOSE:
To determine if RCS het leg level is less than the IRWST actuation setpoint.
SLO 2 BASIS:
Since the PMS/DAS CMT actuation signal is blocked, indicating that reduced RCS inventory operations is anticipated, low RCS hot leg level is used for an inadequate RCS inventory symptom to initiate operator action. Therefore the setpoint for IRWST actuation on low RCS hot leg level is used to detennine if the operator should enter SDG-1, RESPONSE TO LOSS OF RCS INVENTORY DURING SHUTDOWN, because of an inadequate RCS inventory conditions.
ACTIONS:
Detemnine if RCS hot leg level is greater than SLO 2 INSTRUMENTATION:
RCS hot leg level indication CONTROL /EOUIPMENT:
N/A KNOWLEDGE:
The operator should be aware of manual IRWST actuation capability provided by PMS and DAS.
ADDITIONAL INFORMATION:
SLO 2 - RCS hot leg low level IRWST actuation setpoint O
SDR)l.073196 3-4 REVislON: 2
BLOCK DESCRIPTION TABLE FOR SDF-0.13 BLOCK 4 BLOCK:
RNS In Service PURPOSE:
To determine if RNS is in service providing shutdown core cooling BASIS:
This block determines if RNS is in service providing shutdown core cooling, which satisfies the core cooling safety function. If RNS is not providing shutdown cooling then the operator enters SDG-2, RESPONSE TO LOSS OF RNS DURING SHUTDOWN.
ACTIONS:
Detennine if RNS is in service providing effective core cooling INSTRUMENTATION:
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RNS performance status indication (s)
CONTROL /EOUIPMENT-N/A (3
KNOWLEDGE:
N/A ADDITIONAL INFORMATION:
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0 sDronm3196 35 REVisloN: 2
BLOCK DESCRIPTION TABLE FOR SDF-0.13 HLOCK 5 BLOCK:
Containment Radiation Less Than (SR01)
PURPOSE:
To deiermine if contairunent radiation is less than the setpoint value used for the containment high radiation alarm and isolating the containment purge / exhaust systems BASIS:
The containment purge and exhaust system provides outside air to the containment during outages for personnel habitability and is automatically isolated when the containment radiation level is above the alarm setpoint. This action prevents an uncontrolled radiation release to the environment. The containment alann serpoint could be mached if there is RCS leakage into contairunent or if a fuel assembly is dropped and damaged during fuel transfer operations. Therefore the containment radiation setpoint SR01 is used as the symptom for entering SDG-3, RESPONSE TO HIGH CONTAINMENT RADIATION DURING SHUTDOWN.
ACTIONS:
Determine if containment mdiation is less than SR01 INSTRUMENTATION:
i Containment radiation indication CONTROL /EOUIPMENT:
N/A KNOWLEDGE:
N/A ADDITIONAL INFORMATION:
SR01 - Containment radiation setpoint to isolate containment purge and exhaust system.
0 sDF01-073196 3-6 REVIslON: 2
BLOCK DESCRIPTION TABLE FOR SDF-0.1-3
(~N BLOCK 6 L)
BLOCK:
Nuclear Flux Doubling Alarm Clear PURPOSE:
To determine if the nuclear flux doubling alarm will not clear indicating an abnormal reactivity condition BASIS:
The nuclear flux doubling alarm could be reached if abnormal reactivity conditions occur such as an inadvenent RCS dilution, an inadequate shutdown margin condition or if a fuel assembly is misplaced or, during fuel movement operations occurring close to the source range detector (s).
Therefore the nuclear flux doubling alarm is used as an early symptom for entering SDG-4, RESPONSE TO INCREASING NUCLEAR FLUX DURING SHUTDOWN.
ACTIONS:
Determine if the startup range nuclear flux doubling alarm will clear l
INSTRUMENTATION:
Stanup range nuclear flux doubling alarm indication i O CONTROL /EOUIPMENT:
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KNOWLEDGE:
N/A ADDITIONAL INFORMATION:
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BLOCK DESCRIPTION TABLE FOR SDF-0.I-3 BLOCK 7 BLOCK:
RCS Pressure / Temperature Within Cold Overpressure Limits PURPOSE:
To determine if RCS pressure and temperature conditions are within Technical Specification cold ovemressure limits BASIS:
RCS stress (pressure) limits, which are a function of temperature, are limited in accordance with 10CFR50 Appendix G based on material fracture toughness. These limits ensure RCS pressure boundary integrity based on limiting material properties of the limiting component which is the beltline region of the reactor vessel. The Technical Specifications provide specific RCS pressure and i
temperature conditions at which cold overpressure protection should be provided. RCS cold overpressure protection is provided by RNS. Therefore RNS must be aligned, but not necessarily operating, to the RCS to provide RCS cold overpressure protection. The operator enters SDG-5, RESPONSE TO RCS COLD OVERPRESSURE DURING SHUTDOWN, if RCS cold overpressure limits are exceeded.
ACTIONS:
Detennine if RCS pressuir and temperature conditions are within Technical Specification cold overpressure limits INSTRUMENTATION:
RCS pressure indication RCS cold leg temperature indication CONTROL /EOUIPMENT:
N/A KNOWLEDGE:
N/A ADDITIONAL INFORMATION:
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l BLOCK DESCRIPTION TABLE FOR SDF 0.13 BLOCK 8 1
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RCS Temp. Has Remained Within A Plus Or Minus 5'F in the last 10 Minutes PURPOSE:
To detennine if RCS temperature is stable BASIS:
RCS temperature should normally be stable while in cold shutdown and refueling modes of operation. The Shutdown Safety Status Tree is considered Satisfied if all of the preceding blocks are satisfied along with this block. If RCS temperature is changing (i.e., changing mom than 5 degrees in the last ten minutes, then the operator would proceed to the next block to determine if a l
l controlled beatup or cooldown is in progress.
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Determine if RCS temperature is changing l
INSTRUMENTATION:
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RCS temperature indication with trending capability CONTROL /EOUIPMENT:
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K.NOWLEDGE:
N/A ADDITIONAL INFORMATION:
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k sDRI.073196 3-9 REVislON: 2
BLOCK DESCRIPTION TABLE FOR SDF-0.1-3 BLOCK 9 1
BLOCK:
Controlled Heatup Or Cooldown in Progress PURPOSE:
To determine if changes in RCS temperature are expected BASIS:
RCS temperature should nonnally be stable while in cold shutdown and refueling modes of operation unless a contmiled heatup or cooldowT1 are in progress. If a controlled heatup or cooldown is in progress then the Shutdown Safety Status Tree is considered satisfied. If a heatup or cooldown is in progress and was not initiated by the operator, then the temperature change is due to some plant malfunction such as component cooling water failure or service water failure. The operator enters SDG-6, RESPONSE TO UNEXPECTED RCS TEMPERATURE CHANGES DURING SHUTDOWN if a controlled normal heatup or cooldown is not in progress and RCS temperature is not stable.
ACTIONS:
Determine if RCS temperature changes are under operator contml INSTRUMENTATION:
RCS temperature indication with trending capability CONTROL /EOUTPAENT:
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KNOWLEDGE:
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ADDITIONAL INFORM ATION:
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