ML20217Q710

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Rev 0 to Critical Design Characteristics Reactivity Events
ML20217Q710
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Issue date: 08/29/1997
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-

PARSONS POWER Critical Design Characteristics Reactivity Events -

Millstone 2 l

Prepared By:

1 MM Date:

g E7 97 ==

Reviewed By: [

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k. Date: I 25 72 Approved By:

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Tier 2 Revision 0 9709030320 970829 29 August WD PDR ADOCK 05000336 P PDR

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TAHLE OF CONTENTS 1.0 R EA CTIVITY EV ENTS .. . ........ ...... .... .. .. ............ . . .. . ... ... ... ... ,2 2.0 CRITICAL DE'.ilGN CllARACTERISTICS . ..... . .. . . .. .. ....... ... . 7 2.! UNCOETROLLL9 CONTROL ROD / BANK WITilDRAWAL FROM A SUBCRITICAL OR LOW POWER STARTUP CONDITION., ...... .. .... . . . . . . . . . . . . . . . . .. . . . . . . . . . . .7 2.2 UNCONTROLLED CONTROL ROD / BANK WITIIDRAWAL AT POWER....... . . . . . . . . . . . . .......9 2.3 DROPPED CONTROL ROD /B ANK .... ... .... ...... ... ....... . . . ....... .. . ...... . .. .... .. ... . . . . . . .. I 1 l

2.4 SINGLE CONTROL ROD WITIIDRAWAL .................. . . .. ... . ...... . .... . .. . . . .. . ............I3 l 2.5 CVCS MALFUNCTION TilAT RESULTS IN A DECREASE IN Tile BORON l

CONCENTRATION IN TIIE REACTOR COOLANT...... ... ........... . . .. . .. .. . . .. .. .. . ... ... .. .15 l 2.6 SPECTRUM OF CONTROL ROD EJECTION ACCIDENTS ..... ............ . ...... . . . . . . . . . . . . . . . 17 l

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i ATTACllMENT 1 REACTIVITY EVENTS 1.0; REACTIVITY EVENTS 1.1- - FSAR Section 14.4 discusses six design basis events (DBEv's) involving a reactisity or power distribution anomaly; The applicability of each accident for each plant operating mode, and whether an -

analysis was performed by NNECo, is presented in Figure 1. Development of Critical Design Characteristics (CDCs) is based on information provided in FSAR Chapter 14.- These CDCs will be augmented with information derived from FSAR Chapters 6,7, 8 and 9, and the supportmg analyses and calculations. -

Figure 1: Reactivity Events 14.4.1- 14.4.2 14.4.3.1 14.4.3.5- '14.4.6 14.4.8 Rod Bank Rod Bank Dropped Single CVCS Rod:

Plant ' Withdrawal Wdhdrawal Rod / Bank Control Rc,:t induced. Ejection _

Oper. - at Low at Power Withdrawal CMboration Accidents 1 Mode Power l 1 N/A Analyze Analyze Analyze Analyze Analyze L

2 Mode 3 N/A Mode 1 Note 1 Analyze Analyze 3 Analyze -N/A- N/A Note 1- - Analyze Note 2 4 N/A N/A N/A N/A- Analyze N/A-

~5 -N/A N/A-- N/A .N/A Analyze N/A-6- N/A- N/A N/A- N/A- Analyze N/A Analyze - The DBEv was analyzed, by NNECo, for the listed operating mode and the results L summarized in FSAR sections 14.4.

Mode "n" - The DBEv is bounded by the mode "n" case ("n" = 1 - 6).

Note l- FSARTable 14.4.3.5-2 conflicts with FSAR section 14.4.3.5.4 and Table 14.4.1-2 regarding analyses performed for modes 2 and 3. _ _

Note 2 - FSAR Table 14.4.8-2 conflicts with FSAR sections 14.4.8.4 and 14.4.8.5 regarding analyses performed for mode 3.

_ l.2 ' The AMSR Program will " review" the DBEv's listed as " Analyze"in Figure 1. These are:

DBEv 14.4.1 Mode 3 - Uncontrolled rod bank withdrawal from a subcritical condition at 2000 psia.

DBEv 14.4.2 Mode 1 -- Uncontrolled rod bank withdrawal at rated power.

DBEv 14.4.3.1 Mode 1 - Dropped control rod, and control rod bank, at rated power.

DBEv 14.4.3.5 Mode 1 _ Single control rod withdrawal at rated power = ,

DBEv 14.4.6 Modes 1,2,3.- CVCS initiated deboration using 3 charging pumps.

- DBEv 14.4.6 Modes 4,5,6_- CVCS initiated deboration using 2 charging pumps.

DBEv 14.4.8 Mode 1 - Single rod ejection at rated power using BOC and EOC kinetics.

DBEv 14.4.8 Mode 2 - Single rod ejection at hot critical operating cmditions using BOC and EOC kinetics.

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l 1.3 Figure 2 shows the systems involved in the mitigation of the Reactivity Events.

l Figure 2: Tier-2 AMSR - Systems involved in Reactivity Events l 14.4.1 14,4.2 14.4.3.1 14.4.3.5 14.4.6 14.4.7 Rod Bank Rod Bank Dropped Single CVCS Rod Withdrawal Withdrawal Rod / Bank Control Induced Ejection at Low at Power Rod Deboration Accidents SYSTEM Power Withdrawal RCS X X X X X X ,

SillTfDOWN X 4 COOLING RPS X X X X X X CONTROL ROD X X X X X X PRZR SPRAY X PRZR PRESS X RELIEF

_CVCS X X MAIN STEAM X X X X X X MS RELIEF X X X TURBINE X X X X X El-IC X X X X X FEEDWATER X X X X X AFW X X X X X X ELECT DIST X X X X X X EDG X 4

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1.4 Figure 3 shows the Critical Safety Functions that have correspoixting Critical Design Characteristics for each of the analyzed accidents.

l Figure 3: Tier-2 AMSR - Reactivity Events l

14.4.1 14.4.2 14.4.3.1 14.4.3.5 14.4.6 14.4.8 l Rod Bank Rod Bank Dropped Single CVCS Rod Withdrawal Withdrawal Rod / Bank Control Induced Ejection Critical Safety at Low at Power Rod Deboration Accidents Function Power Withdrawal Reactivity X X X X X X Fuel Integrity X X X X X

  • X X-RCS Pressure & * *
  • X Inventory Contain Integrity * *

& Radiation Control Electrical Power X X X X X X

Essential Support Systems Environmental Control "

  • To be determined from detailed analyses 4 Resision 0 29 August 1997

r l.5 %c analyzed event duration, Minimum Departure from Nucleate Boiling Ratio (MDNDR) and Maximum Linear l{ cat Generation Rate (Max LilGR), as documented in FSAR chapter 14 for each analyzed event, are presented in Figure 4.

Figure 4: Tier 2 AMSR Reactivity Events FSAR SECTION 14.4 ANALYZED DESIGN BASIS Analyzed MDNBR Max EVENT Duration (sec) L11GR DBEv 14.4.1 Mode 3 - Uncontrolled rod bank withdrawal ~30 Note 1 20.0 from a critical condition at 2000 psia.

DBEv 14.4.2 Mode 1 - Uncontrolled rod bank withdrawal ~520 1.21 19.1 at rated power.

DBEv 14.4.3.1 Mode 1 - Dropped control rod bank at rated

  • 1.21 18.6 power.

DBEv 14.4.3.5 Mode 1 - Single control rod withdrawal at

  • Note I <21 rated power.

DBEv 14.4.6 Modes 1,2,3 - CVCS initiated deboration Various *

  • using 3 charging pumps.

DBEv 14.4.6 Modes 4,5,6 - CVCS initiated deboration Various N/A N/A using 2 charging pumps.

DBEv 14.4.8 Mode 1 - Single rod ejection at rated power ~12 Note 2 Note 3 using BOC and EOC kinetics.

DBEv 14.4.8 Modes 2,3 - Single rod ejection at hot zero

  • Note 2 Note 3 power using BOC and EOC kinetics.

Results not available in FSAR section 14.4.

Note 1: Event analyzed with respect to Fuel Centerline Melt Criteria only.

Reference:

FSAR Table 14.0 3.

Note 2: Fuel failure less than i1.5%

Note 3: Total fuel enthalpy less than 280 cal /gm.

l.6 Critical Design Characteristics Development Method The following method was used to develop CDCs for Reactivity Events. Six design basis events (DBEv's) invohing a reactivity or power distribution anomaly are described in section 14.4 of the FSAR. Each event was reviewed and design inputs extracted. Each design input was assigned to one or more Critical Sarey Functions (CSFs). He CSF diagrams were then used to develop functional / system level CDCs for each event.

1.7 System Boundary Diagrams System Boundary Diagrams (SBDs) are developed for each accident mitigation system. Using the SBDs, the AMSR Program Team will identify the system configuration and component actions required to meet the system / functional CDCs. This information will be loaded into the Tier-2 Data Base and will constitute the Chapter 14 requirement at the component level.

1.8 CDC Validation The CDCs will be validated "as present in the installed plant configuration. The validation method will be determined following review of the detailed t nalyses supporting the FSAR Chapter 14 events.

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Millstoned system and component test data will be used to the maximum extent possible to perfonn this

- validation. When CDCs cannot be validated by test, then analysis or alternate means will be used to -

- perform the validation.

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2.0 -- CRITICAL DESIGN CllARACTERISTICS A discussion of the Reactivity Events is presented in sections 2.1 through 2.6 of this attachment. The functional / system CDC listing is included. These CDCs will be augmented with information derived from FSAR Chapter 6,7,8 and 9, and the detailed analyses and calculati that support FSA.R Chapter 14.

2.1 UNCONTROLLED CONTROL ROD / BANK WITilDRAWAL FROM A SUBCRITICAL OR LOW POWER STARTUP CONDITION 2.1.1 EVENT DESCRIPTION This event is initiated by an uncontrolled control rod / bank withdrawal from a subcritical or low power startup condition. The MNPS-2 Low Power Control Rod / Bank Withdrawal analysis is described in FSAR Section 14.4.1.

2.1.2 DESIGN BASIS

'The MNPS-2 Low Power Control Rod / Bank Withdrawal analysis is based on the following primary assumptions:

a. Most reactive rod stuck in its fully withdrawn position.

Reference:

FSAR Section 14.0.6

b. Single failure criteria applies to the RPS which is designed as redundant and single failure proof.

Referenec: FSAR Section 14,4.1.4.

c. CVCS (Letdown) system in operation.

Reference:

FSAR Table 14.4,1-3.

r 2.1.3 SYSTEMINTERFACE The following systems interface during th Low Power Control Rod / Bank Withdrawal event:  ;'

a. Control Element Drive i i
b. Reactor Coolant System I
c. Reactor Protection System
d. Pressurizer Pressure Control System
e.  ;

CVCS (Letdown)

f. Main Steam ,
g. Main Steam Relief
h. Electrical Distribution 2.1.4 EVENT DISPOSITION 1 The event initiated from a mode 3 condition at 2000 psia bounds all other low power or suberitical  !

cases. The mode I case is considered in FSAR section 14.4.2. '

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2.1.5 FUNCTIONAL / SYSTEM CDCs - EVENT 14.4.1:

nc Critical Design Characteristics for the Low Power Control Rod / Bank Withdrawal Event, Mode 3, are presented below.

2.1.5.1 REACTIVITY CONTROL CSF Egnetional/ System CDQ - Insert control rods on Variable Overpower Trip,

Reference:

FSAR Section 14.4.1.6, Table 14.4.1-1, Table 14.4.1-3.

Functional / System CDCs - Initiate Rod Withdrawal Prohibit on Variable Overpower Pre-trip Alarm.

Reference:

FSAR Section 14.4.1.3 (3), Table 14.4.1 1.

2.1.5.2 FUEL INTEGRITY 5 CORE 11 EAT REMOVAL CSF I

Functional / System CDQ - Functional / System CDCs included in 2.1.5.1 above.

2.1.5.3 RCS l{ EAT REMOVAL CSF l

Functional / System CDCs - Ma n Steam Relief Valves relieve steam per analysis assumed values.

Reference:

FSAR FiSure 14.4.1-6.

( 2.1.5.4 RCS PRESSURE & INVENTORY CONTROL Functional / System CDCs - Functional / System CDCs to be determined from review of detailed analyses.

2.1.5.5 CONTAINMENT INTECT1 ( & RADIATION CONTROL CSF - No applicable functional / system CDCs.

2.1.5.6 ELECTRICAL POWERfSE Functional / System CDCs - Maintain power to plant loads from offsite power source.

2.1.5.7 ESSENTIAL SUPPORT SYSTEMS CSF - No applicable functional / system CDCs.

2.1.5.8 ENVIRONMENTAL CONTROL CSF - No applicable functional / system CDCs.

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p 2.2 - UNCONTROLLED CONTROL ROD / BANK WITilDRAWAL AT POWER

- 2.2.! EVENT DESCRIPTION -

his event is initiated b'y an uncontrolled control rod / bank withdrawal from full rated power. He i-MNPS 2 Control Rod / Bank Withdrawal analysis is described in FSAR Section 14.4.2.

t

- 2.2.2 DESIGN BASIS De MNPS-2 Control Rod / Bank Withdrawal analysis is based on the following primary assumptions:

. a. Most reactive rod stuck in its fully withdrawn position.

Reference:

FSAR Section 14.0.6 -

, b. Single failure criteria applies to the RPS which is designed as redundant and single failure proof.

Reference:

FSAR Section 14.4.2.4

c. CVCS (Letdown) system in operation.

Reference:

FSAR Table 14.4.2-3 i-2.2.3 '. SYSTEM INTERFACE l The following systems interface during the dropped control rod / bank event:

0 4

a. Control Element Drive t b, Reactor Coolant System I c. Reactor Protection System
- d. CVCS (Letdown)
e. Main Steam System

- f. Main Steam Relief

g. Turbine (Stop Vahrs) :

i h. Electro-Hydraulic Control System

i. Electrical Distribution -

1 l- 2.2.4 EVENT DISPOSITION-l The full power case bounds all power operating cases for modes 1. The mode 2 through 6 cases are considered in FSAR section 14.4.1.

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2.2.5 FUNCTIONAL / SYSTEM CDCs - EVENT 14.4.2:

The Critical Design Characteristics for the Control Rod / Bank Withdrawal Event, Mode 1, are presented below.

2.2.5.1 REACTIVITY CONTROL CSE Functional / System CDCs - Insert control rods on Variable Overpower or TM/LP Trip.

Reference:

FSAR Section 14.4.2.4, Table 14.4.21, Table 14.4.2 3. '

- 2.2.5.2 FUEL INTEGRITY & CORE HEAT REMOVAL CSF Functional / System CDCs - Functional / System CDCs included in 2.2.5.1 above.

2.2.5.3 RCS HEAT REMOVAL CSE l

Functional / System CDCg - Trip turbine on reactor trip.

Reference:

FSAR Table 14.4.2-3.

Functional / System CDCs - Main Steam Relief Valves relieve steam per analysis assumed values.

Reference:

FSAR Table 14.4.2-3.

2.2.5.4 RCS PRESSURE & INVENTORY CDNTROL - No active systems challenged. No applicable functional / system CDCs.

2.2.5.5 C_ONTAINMENT INTEGRITY & RADIATION CONTROL CSF - No applicable functional / system CDCs.

2.2.5.6 ELECTRICAL POWER CSF Functional /S, stem CDCs - Transfer loads to offsite power source following turbine trip.

2.2.5.7 ESSENTIAL SUPPORT SYSTEMS CSF -No applicable functional / system CDCs.

2.2.5.8 ENVIRONMENTAL CONTROL CSF - No applicable functional / system CDCs.

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2.3 DROPPED CONTROL ROD / HANK l l

1 2.3.1 EVENT DESCF9T10N

- The dropped control rod and dropped control rod bank events are initiated by a deenergized control rod drive rnect anism or by a malfunction associated with a control cod bank. De MNPS 2 Dropped j Control Rod / Hank analysis is described in FSAR Section 14.4.3.1. -

l 1 2.3.2 DESIGN HASIS l nc MNPS 2 Droppc<l Control Rod / Hank analysis is based on the following primary assumptions:

1 -

i

! a. Most reactive rod stuck in its fully withdrawn position.

Reference:

FSAR Section 14.0.6

b. Single failure criteria applies to the RPS which is designed as redundant and single failure proof.

Referenec: FSAR Section 14.4.3.1.4.

2.3.3 SYSTEM INTERFACE

]

, The following systems interface during the dropped control rod /bara event:

a. Control Element Drive I
b. Reactor Coolant System  ;
c. Reactor Protection System .

j d. Main Steam System .

t c ' Turbine (Stop Valves) .

f. Electro Hydraulic Control System l (
g. Electrical Distribution y f

i 2.3.4 EVENT DISPOSITION ne full power case bounds all power operating cases for mode 1. Single rod drop and bank rod drop ,

j cases were analyzed. The mode I case bounds the mode 2 case.' ne event does not apply for plant modes 3 through 6.

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2.3.5 FUNCTIONA1/ SYSTEM CDC: E' ENT 14.4.3.1:

'lho Critical Design Characteristics for the Dropped Control Rcd / Bank Event, Mode 1, are presented below.

2.3.5.1 EUACTIVITY CONTROL CSE Functional / System CDCs Insert control lods on Variable Overpower Trip.

Reference:

FSAR Section 14.4.3.1.3,14.4.3.1.5 Table 14.4.3.1 1.

2.3.5.2 EUJiL INTEGRITY & C0]LEJ1 EAT REMOVAL.CSE Functional / System ClO Functional / System CDCs included in 2.3.5.1 above.

2.3.5.3 BCS IIEAT REMOVAL CSF Functional l System CDCs Functional / System CDCs to be determined from review of detailed analyses.

2.3.5.4 RCS PRESSURE & INVENTORY CONTROL No active systems challenged. No applicable functional / system CDCs.

Reference:

FSAR Section 14.4.3.1.4.

2.3.5.5 CONTAINMENT INTEGRITY & RADIATION CONTROL CSF No applicable functional / system CD':s.

2.3.5.6 ELECTRICAI. POWER CSF Functional /Svstem CDCs - Transfer loads to ofTsite power source on turbine trip.

2.3.5.7 ESSENTIAL SUPPORT SYSTEMS CSF - No applicable functional / system CDCs; 2.3.5.8 ENVIRONMENTAL CONTROL CSF No applicable functional / system CDCs, l

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2.4 SINGLE CONTROL ROD WITilDRAWAL 2.4.1 EVENT DESCRIPTION I The single control rod withdrawal event is initiated by the inadvertent withdrawal of a single CEA from the core. His event can only occur as the result of multiple wiring failures or multiple operator actions  !

in disregard of available event indication. No single electrical or mechanical failure in the rod control system could cause this event to occur during full power operation. nis event is postulated for design i purposes. _ liigh radial power peaking, localized in the region of the single withdrawn CEA, may surpass design limits in a severe case, and assemblies in the vicinity may experience boiling for a short time.

Some fuel damage may occur. The event is terminated by the reactor protection system. The MNPS 2 i single control rod withdrawal analysis is described in USAR Section 14.4.3.5  ;

2.4.2 - DESIGN HASIS he MNPS 2 single control rod withdrawal analysis is based on the following primary assumptions:

a. Most reactive rod stuck in its fully withdrawn position.

Reference:

FSAR Section 14.0.6

b. Reactor trip on Variable Overpower or other trip function. Reference FSAR Section 14.4.3.5.3.
c. Single failure criteria for this event is not discussed in FSAR section 14.4.3.5.

2.4.3 SYSTEM INTERFACE he following systems interface during the single control rod withdrawal analysis:

a. Control Element Drive

- b. Reactor Coolant System

c. Reactor Protection System
d. Main Steam System
c. Turbine (Stop Valves) .
f. Electro-Hydraulic Control System
g. Electrical Distribution ~

2.4.4 EVENT DISPOSITION i

De event was analyzed at rated power conditions for ny;de 1. FSAR Table 14.4.3.5 2 conflicts with .

FSAR section 14.4.3.5.4 and Table 14,4.1-2 regarding analyses performed for modes 2 and 3, De mode 2 case appears to be bounded by the control rod bank witi.drawal event (14.4.1) mode 2 case.

De mode 3 case appears to be bounded by the control rod barl withdrawal cycnt (14.4.1) mode 3.

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2.4.5 FUNCTIONAL > SYSTEM CDCs EVENT 14.4.3.5:

'lhe Critical Design Characteristics for the single control rod withdrawal event, Mode I, are presented

below.

2.4.5.1 BEACTIVITY CONTROL CSE a

Functional / System CDCs Insert control rods on Variable Overpower or other trip function.

1 Reference.' FSAR Section 14.4.3.5.3, Table 14.4.3.5 1.

I Functional / System CDCs Initiate Rod Withdrawal Prohibit on Variable Overpower Pre-trip Alarm.

Refer:nce: FSAR Section 14.4.3.5.3 (5), Table 14.4.3.5 1.

2.4.5.2 FUEL INTEGRITY & CORE HEAT REMOVAL CSF  !

FunctionaVSystem CDCs - Fuel failure is less than 11.5% and is thus bounded by the control rod ejection event (14.4.8). Functional / System CDCs to be determined from review of detailed analyses.

, Reference FSAR Section 14.4.3.5.6.

2.4.5.3 RCS 11 EAT REMOVAL CSF Functional / System CDCs Functional / System CDCs to be determined from review of detailed analyses.

, 2.4.5.4 RCS PRESSURE & INVENTORY CONTROL, FunctionaVSystem CDCs - Funct onal/ i System CDCs to be determined from review of delled . ,

analyses.

1 2.4.5.5 CONTAINMENT INTEGRITY & RADIATION CONTROL CSF ,

4-

_ Functional /Svetem CDCs - Functional / System CDCs to be determined from review of detailed analyses.

2.4.5.6 ELECTRICAL POWER CSF Functional / System CDC: - Transfer loads to offsite power source following turbine trip.

2.4.5.7 ESSENTIAL SUPPORT SYSTEMS CSE - No applicable functional / system CDCs.

i .

2.4.5.8 ENVIRONMENTAL CONTROL CSF -No applicable functional / system CDCs.

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2.5 CVCS MALFUNCTION TilAT RESULTS IN A DECREASE IN Tile IlORON CONCENTRATION IN Tile REACTOR COOi, ANT.

2.5.1 EVENT DESCRIPTION

, This event is initiated by the addition of demineralir.ed water into the RCS sia the Chemical Volume and Control System (CVCS). The CVCS Initiated Deboration Event is described in FSAR Section 14.4.6.

2.5.2 DESIGN DASIS The CVCS Initiated Deboration Event analysis is based on the following primary assumptions:

a. Reactor protection is provid$ by a combination of RPS trip functions and/or operator resp time.

Reference:

FSAR section 14,4.6.3.

b. Single failure criteria for this event is not discussed in FSAR section 14.4.6.

2.5.3 SYSTEM INTERFACE The following systems interface during the postulated CVCS Initiated Deboration Event analysis:

a. CVCS (CharB ing)
b. Reactor Coolant System
c. Control Element Drive
d. Shutdown Cooling System
c. Reactor Protection System
f. Main Steam System
g. Turbine (Stop Valves)
h. Electro-llydraulic Control System
i. Electrical Distribution 2.5.4 EVENT DISPOSITION The event is analyral for modes I through 6.
a. For modes I and 2, the power excursion is terminated by a reactor trip. His event is bounded by the Uncontrolled Control Rod / Bank Withdrawal Events (14.4.1 and 14.4.2), since the deboration reactivity insertion rates are less than those used in the rod withdrawal events,
b. For mode 3, the response time to prevent criticality is 141 minutes, which is conservative relative to the 15 minute acceptance c-ittria.
c. For modes 4 and 5, the requnc. \.6% shutdown margin is not reduced to 0% within the 15 minute l allowable operator response tin.c.

l

d. For mode 6, the required 5.0% shutdown margin is not reduced to 0% within the 30 minute allowable operator response time. De minimum required shutdown cooling system flow is also specified.

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2.5.5 FUNCTIONAL / SYSTEM CDCs + EVENT 14.4 6:

The Critical Design Characteristics for the CVCS Initiated Deboration Event, Modes I through 6, are presented below.

2.5.5.1 REACTIVITY CONTROL CFF Functig.nal/ System CDCs - Insert control rods on Variable Overpower or other RFS trip function.

Reference:

FSAR Section 14.4.6.6, Table 14.4.61.

l Functional / System CDCs . Limit charging system flow to 132 gpm for modes I,2 and 3. Limit clnrging syttem flow to 88 gpm for modes 4,5 and 6.

Reference:

FSAR section 14.4.6.1. Table 14.4.6 3.

Functional / System CDCs - Maintain a minimum of 950 gpm shutdown cooling system flow in mode 6.

Reference:

FSAR Section 14.4.6.5, Table 14.4.6 3.

Functional / System CDCs Control roun operator identify and mitigate the event within 15 minutes (modes 3,4 and 5) or 30 minutes (mode 6) from the onset of the dilution.

Reference:

FSAR Section 14.4.6.4. .

2.5.$.2 EUEL INTEGRITY _& CORE IIEAT Ri?MOVAL CSF Functional / System CDC: Functional / System CDCs included in 2.5.5.1 above.

2.5.5.3 RCS IIEAT REMOVAL CSE Functional / System CDCs - Trip turbine on reactor trip.

2.5.5.4 RCS PRESSURE & INVENTORY CONTRQL EunctionaVSystem CDCs FunctionaVSystem CDCs to be determined from review of detailed analyses.

- 2.5.5.5 CONTAINMENT INTEGRITY & RADIATION CONTROL CSE - No applicable functionaVsystem CDCs.

2.5.5.6 ELECTRl_ CAL POWER CSF FunctionaVSystem CDC: Transfer loads to offsite power source followir g turbine trip.

' 2.5.5.7 ESSENTIAL SUPPORT SYSTEMS CSF - No applicable functionaVsystem CDCs.

- 2.5.5.8 ENVIRONMENTAL CONTROL CSF - No applicable functionaVsystem CDCs.

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2,6 SPECTRUM OF CONTROL ROD IMECTION ACCIDENTS 2.6.1 EVENT DESCRIPTION nis accident is laitiated by a failure in the control rod drive pressure housing which could result in the rapid ejection of a control rod. In addition to the rod ejection, the event is characterized by a small break loss of coolant accident (SDLOCA). He short term aspects of the event are dominated by the rod ejection, while the long term aspects are dominated by the SBLOCA. The MNPS 2 Control Rod Ejection Accident analysis is described in FSAR Section 14.4.8. He long term aspects of the rod ejection event are bounded by the SBLOCA analysis (Event 14.6.5) 2.6.2 DESIGN BAS!S The MNPS 2 Control Rod Ejection Accident analysis is based on the following primary assumptions:

a. For the evaluation of the DNBR and pressurization consequences, concurrent loss of offsite power is assumed.

Reference:

FSAR Section 14.4.8.5.

b. No credit is taken for the variable overpower trip in the analysis of the pressurization consequences of a control rod ejection.

Reference:

FSAR Section 14.4.8.5.

c. No credit is taken for PORV actuation.

Reference:

FSAR Table 14.4.8-3.

d. No credit is taken of operation of the condenser dump system.

Reference:

FSAR Table 14.4.8 3, Table 14.4.8-4.

c. Pressurizer heaters are energized for the Maximum Pressurization case.

Reference:

FSAR Table 14.4.8-3.

f. He Charging Pumps are operating for the Maximum Pressurization case.

Reference:

FS AR Table 14.4.8 3.

g. He CVCS (Letdown) is in operation for the Minimum DNBR case.

Reference:

FSAR Table 14.4.8-4.

2.6.3 SYSTEM INTERFACE The following systc>ns interface during the postulated Control Rod Ejection Accident analysis:

a. Control Element Drive
b. Reactor Coolant System
c. Reactor Protection System
d. CVCS (Charging & Letdown)
c. Pressurizer Pressure Relief System
f. Main Steam System
g. Turbine (Stop Vahes)
h. Main Steam Relief System
i. Electro-llydraulic Control System J. Electrical Distribution
k. Emergency Power System 17 Revision 0 29 August 1997

9 2.6.4 EVENT DISPOSITION 1hc mode i case at full rated power is the limiting case for power operating initial conditions. The event is also analyzed at hot critical operating conditions (modes 2). Separate analyses are perfonned for deposited energy, DNBR, and PCS pressurization for each of the initial operating conditions. HOC and EOC conditions were considered.

2.6.5 FUNCTIONAL / SYSTEM CDCs EVENT 14.4.8:

Ihe Csitical Design Characteristics for the Control Rod Ejection Accident Event, Modes I and 2, are presented below, 2.6.$.1 REACTIVITY CONTROL QE fant.tlonal/ System CDCs Insert control rods on Pressurizer liigh Pressure or other RPS trip function.-

Reference:

FSAR Table 14.4.81, Table 14.4.8 3, Table 14.4.8 4.

2.6.5.2 FUEL INTEGRITY & CORiulEAT REMOVAL GE Functional / System CDCs Fuel failure is less than i1.5%. Functional / System CDCs to be determined from review ofdetailed analyses. Reference FSAR Section 14 4.8.6.

2.6.5.3 BC.S_IIEAT REMOVAL CSF Functional /Syst' ' i.CDCs - Trip turbine on reactor trip.

Functional / System CDCs - Main Steam Relief Valves relieve steam per analysis assumed values.

Reference:

FSAR Table 14.4.8 3, Table 14.4.8-4.

2.6.5.4 RCS PRESSURE & INVENTORY CONTROL Functional / System C.QQ - Pressurizer safety valves relieve steam to maintain RCS pressure less than 110% of design value.

Reference:

FSAR Section 14,4.8.6, Table 14.4.8-3 2.6.5.5 CONTAINMENT INTEGRITY & RADIATION CONTROL CSF Functional / System CDCs - Functional / System CDCs to be determined from review ofdetailed analyses.

. 2.6.5.6 ELECTRICAL POWER CSF Functional / System CDCs - Diesel Generator start and provided power to accident loads.

Reference:

FSAR Section 14,4.8.5.

-2.6.5.7 ESSENTIAL SUPPORT SYSTEMS CSF - No applicable functional / system CDCs.

2.6.5.8 ENVIRONMENTAL CONTROL CSF - No applicable functional / system CDCs.

18 Revision 0 29 August 1997 l

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