IR 05000245/1989019
| ML20012E171 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 03/16/1990 |
| From: | Conte R, Gallo R, Sisco C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20012D826 | List: |
| References | |
| 50-245-89-19-MM, NUDOCS 9003300170 | |
| Preceding documents: |
|
| Download: ML20012E171 (44) | |
Text
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b U. S. NUCLEAR REGULATORY COMMISSION
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REGION I
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' Meeting No. 90-20-Report No.. 50-245/89-19
' Docket No.-
50-245
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License No. DPR-21 Licensce:
Northeast Nuclear Energy Company
Facility Name: Millstone Nuclear Power Station Unit 1 I
s Meeting lAt:
NRC Region I Office, King of Prussia, Pennsylvania
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Meeting Conducted:
March 1, 1990 Prepared by:
Cd Sw 3//-
FO C.-Sisco, Operation Engineer
'Date/
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R'ichardJ.'ContpChief.
Cate BWR Section, Operations Branch, DRS
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D Approved by:
Robert M. Gallo, Chie4 [
Oate J
Operations Branch
. Division of Reactor Safety Meeting Summary:
f A significant licensee meeting (Meeting No. 90-20) was conducted on March 1, l1990, at the NRC Region I' Office in King of Prussia to discuss the Unresolved
. Items-documented in Inspection Report No. 50-245/89.19 on the Millstone 1
- Emergency Operating Procedures and the related NRC staff concerns documentcd in
" NRC letter, dated February 15, 1990.
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The NRC staff held detailed discussions with the licensee onythe identified
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concerns.
The NRC staff concluded that additional staff rev'rew of the concerns-4
..is' appropriate.
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PDR ADOCK 05000245
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DETAILS 1.
Introduction On March 1, 1990, at the NRC Region I office in King of Prussia, Pennsyl-vania.the personnel whose names are listed in Attachment 1 of this report met to discuss the Unresolved Items associated with Millstone-l's Emer-gency Operating Procedures (EOPs)-identified in Section 3 and 4 of NRC-Inspection Report No. 50-245/89-19. The Unresolved Items are, in summary:
1)
The-licensee s technical justification for the licensee's dev'iation from the Boiling Water Reactors Owner's Group (BWROG) Emergency Procedure Guidelines (EPG) Revision 4 (accepted by NRC staff safety evaluation report) was incomplete.
2)
Inconsistent application of administrative controls of the 590 series supplemental _ procedures related to Emergency Operating Procedures (EOP) implementation.
3)
Weak validation and verification program for E0P revisions.
4)
A lack of E0P entry conditions for some monitored and unmonitored radiation release points.
5)
A lack of operator training regarding determination of RPV water level during degraded primary containment conditions.
6)
Weak implementation of Human Factors principles.
The NRC staff reviewed the licensee's justification for major deviations from the EPGs. The results of this review are documented in an NRC letter (a supplemental safety evaluation report), dated February 15, 1990, to the licensee.
In summary, this review resulted in the the following concerns:
1)
Adequacy of Licensee Criteria for Containment Flooding 2)
Adequacy of Licensee Criteria for Emergency Depressurization 3)
Effectiveness of steam cooling at low RPV pressure 4)
Effectiveness of Isolation Condenser operation at low RPV pressure
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The NRC management introduced _ these topics and' asked the licensee to present its position, perspective, and proposed corrective actions.
2.
Licensee Presentation The licensee addressed the technical concerns in NRC letter, dated February
'15, 1990, and Unresolved Item (No. 245/89-19-01) from the last E0P inspec-tion utilizing the text of Attachment 2.
The licensee's position and
_ perspective on each of the NRC concerns indicated that they felt justified in the action they took to incorporate EPG, Revision 4, into their plant specific E0Ps. As a result of NRC staff discussions, it was concluded-that additional NRC staff review of the concerns is necessary.
The other unresolved items of the inspection report (Nos. 50-245/89-19-02 to 06) were also discussed. Overall, the licensee representatives indi-cated their intent to take corrective actions, where appropriate, but they-noted that they did not agree and/or understand sonie of the specific NRC staff comments. The NRC staff agreed to discuss specifics at a future date.
3.
Conclusion The licensee presented detailed discussions on its position and perspec-tivo of each of the concerns identified by the NRC.
The NRC staff
. concluded from detailed discussions with the licensee that additional staff review of the concerns is warranted.
Attachments:
1.
Meeting Attendees 2.
Licensee's Presentation
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Attachment 1 Meeting Attendees
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Northeast Nuclear Energy Company Dr. C. Frederick Sears, Vice President, Nuclear & Environmental Engineering John P. Stetz, Unit Director, Millstone Unit 1 Raymond J. Palmieri, Operations Manager, Millstone Unit 1 Nirmal K. Jain, Senior Engineer, Safety Analysis Paul A. Blasioli, Supervisor,- Nuclear Licensing Michael S. Kai, Supervisor, Safety Analysis Richard C. Kraemer, Shift Supervisor, Millstone Unit 1 Peter J. Miner, Scientist, Nuclear Licensing
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Christopher J. Tabone, Senior Instructor, Operations Training
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2.
Nuclear Regulatory Commission (NRC)
F Wayne-Hodges, Director, Division of Reactor Safety (DRS)
Robert Gallo, Chief, Operations Branch, DRS
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Richard Conte, Chief, BWR Section, DRS
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Carl Sisco, Operations Engineer, DRS
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l-Brian Hughes, Operations Engineer, DRS l
l Donald Florek, Senior Operations Engineer, DRS Tracy Walker, Senior Operations Engineer, DRS Donald Haverkamp, Chief, Reactor Projects Section 4A, Division of Reactor Projects (DRP)
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Tony Vegel, Reactor Engineer, DRP
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Robert Jones, NRR Michael Boyle, NRR George Thomas, NRR John Monninger, NRR/SPCB Jack Kudrick, NRR/SPCB
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William Raymond, Senior Resident Inspector Doug Demosey, Resident.'.spector
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LICENSEE PRESENTATION MILLSTONE 1 EMERGENCY OPERATING PROCEDURES MARCH 1, 1990
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DOCKET NO. 50-245-
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EMERGENCY OPERATING PROCEDURES MEETING WITH NRC KING OF PRUSSIA, PA
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L NORTHEAST NUCLEAR ENERGY COMPANY MARCH 1, 1990
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INTRODUCTION C. F. SEARS
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- PLANT MANAGEMENT PERSPECTIVE J. P..STETZ
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OVERVIEW R. J. PAU4IERI-
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TECHNICAL DISCUSSION N. K. JAIN
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-' CONCLUSIONS J. P. STETZ
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PARTICIPANTS
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DR. C. FREDERICK SEARS VICE PRESIDENT, NUCLEAR &
ENVIR0lMENTAL ENGINEERING JOHN P. STETZ UNIT DIRECTOR, MILLSTONE UNIT 1 RAYMOND J. PALMIERI OPERATIONS MANAGER, MILLSTONE UNIT 1 NIRMAL K. JAIN SENIOR ENGINEER, SAFETY ANALYSIS PAUL A. BLASIOLI SUPERVISOR, NUCLEAR LICENSING MICHAEL S. KAI SUPERVISOR, SAFETY ANALYSIS RICHARD C. KRAEMER SHIFT SUPERVISOR, MILLSTONE UNIT 1 PETER J. MINER SCIENTIST, NUCLEAR LICENSING CHRISTOPHER J. TABONE SENIOR INSTRUCTOR, OPERATOR TRAINING
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DVERVIEW
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o BWROG EPGs PROVIDE GENERIC GUIDANCE FOR l-PLANT-SPECIFIC E0P DEVELOPMENT.
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EPGs B0UND ALL PLANTS AND SCENARIOS.
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o DESIGN BASES AND EPGs EVALUATED TO DETERMINE OPTIMUM E0Ps FOR MILLSTONE UNIT 1.
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o TECHNICAL DEVIATIONS TO EPGs WERE DEEMED l
JUSTIFIED TO BETTER OPTIMIZE MILLSTONE UNIT 1 L
E0Ps.
o DEVIATIONS RECOGNIZED TO BE WORTHY OF DISCUSSION I
WITH THE NRC.
o THROUGHOUT THE E0P DEVELOPMENT PROCESS, NNECO l-INDICATED OUR DESIRE TO MEET WITH NRC TO DISCUSS l
DEVIATIONS PRIOR TO E0P IMPLEMENTATION.
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- o DEVIATIONS PRESENTED TO BWROG.
o E0Ps IMPLEMENTED ON SEPTEMBER 1, 1989.
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o REVISED PROCEDURES GENERATION PACKAGE AND DEVIATIONS JUSTIFICATION DOCUMENT SUBMITTED ON
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o NRC E0P AUDIT CONDUCTED OCTOBER 23-27, 1989.
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o NRC INTERIM EVALUATION ISSUED FEBRUARY 15, 1990.
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o E0P INSPECTION REPORT ISSUED FEBRUARY 21, 1990.
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o MILLSTONE UNIT 1 E0Ps ARE OF HIGH QUALITY AND BEST ASSURE PUBLIC HEALTH AND SAFETY.
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ISSUES IDENTIFIED IN.JHE. INTERIM EVALUATION
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CRITERIA FOR CONTAllNENT FLOODING (CF).
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CRITERIA FOR EMERGENCY RPV DEPRESSURIZATION (DEP).
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STEAM COOLING AT LOW PRESSURE.
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EFFECTIVENESS OF ISOLATION CONDENSER (IC) AT LOW PRESSURE.
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1. CONTAIMENT FLOODING (CF).
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PERFORM CF IF RPV LEVEL RENAINS BELOW TAF.
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W1.E0P. CRITERIA:
PERFORM CF AFTER RPV DEPRESSURIZATION IF RPV LEVEL REMAINS BELOW 1/2 CORE HEIGHT WITH AT LEAST 1 CORE
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SPRAY PUMP RUNNING, DR
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RPV LEVEL REMAINS BELOW TAF WITH NO CORE SPRAY PUMP y
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o CF REQUIRES VENTING OF BOTH CONTAINMENT AND RPV OUTSIDE CONTAIMENT.
VENTING POINT - DRYWELL.
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o CF.IS REQUIRED FOR THE SCENARIOS WHERE IT IS NOT
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.CQlSITIONS EP_G MP1 E0Ps l
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1/2 CORE HT. < LEVEL s TAF
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2 CS PUMP OPERATING CF NO CF i
1 CS PUMP OPERATING CF NO CF 0 CS PUMP OPERATING CF CF
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LEVEL < 1/2 CORE HT.
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EXAWLE:
DOUBLE EWED RECIRC. PIPE _ BREAK
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AFTER BLOWOWN, RPV LEVEL RECOVERS TO 2/3 CORE HEIGHT (JET PUMP ELEVATION), WITH AT LEAST ONE CORE SPRAY PUMP RUNNING.
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INITIATE CONTAIMENT FLOODING
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THE DRYWELL ABOUT 5 HOURS LATER DRYWELL IS VENTED DUE TO
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THE PRIMARY CONTAI MENT PRESSURE LIMIT.
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SINCE RPV LEVEL > 1/2 CORE HEIGHT WITH ONE
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CORE SPRAY PUMP RUNNING, ACTIONS FOR CONTAINMENT FLOODING ARE NOT TAKEN.
ADEQUATE CORE COOLING HAS BEEN DEMONSTRATED
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FOR THIS CONDITION BY APPENDIX K LOCA ANALYSIS.
VENTING OF THE RPV AND DRYWELL AND ASSOCIATED
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RADIOLOGICAL CONSEQUENCES ARE AVOIDED.
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BASES FOR EPG CRITERIA:
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EFFECT 0F STEAN ON CORE SPRAY PATTERN
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RELIANCE ON CORE SPRAY r
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CONTAI MENT WOULD ULTIMATELY HAVE TO BE FLOODED i
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EFFECT OF STEAM ON CORE SPRAY PATTERN i
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FOR MP1 TYPE Pl. ANTS, THIS EFFECT IS MINIMAL, ESPECIALLY AT LOW PRESSURE (< 50 PSIG).
J OPEN ELBOW SPRAY N0ZZLES.
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RPV IS DEPRESSURIZED BY SRVs AND BREAK.
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MP1 BEST ESTIMATE ANALYSIS BY GE SHOWS PCT
< 1800 F WITH ONE CORE SPRAY RUNNING,
IRRESPECTIVE OF RPV LEVEL.
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RELIANCE ON CORE SPRAY
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PROBABILITY OF FAILURE TO RUN IS 7 x 10-6 IN
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24 HRS FOR MPl.
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REDUNDANT SYSTEM - 2 PUMPS.
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o PUMPS WILL OPERATE WITHIN NPSH AND l
VORTEX LIMITS.
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o WITH NO CORE SPRAY, MP1 SPECIFIC BEST ESTIMATE ANALYSIS SHOW ADEQUATE STEAM COOLING
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WITH LEVEL DOWN TO 1/2 CORE HEIGHT.
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CONTAIl#4ENT WDULD ULTIMATELY HAVE TO BE FLO_QI1ED l
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o A DELAY IN STARTING CF AT 1/2 CORE HEIGHT vs.
TAF IS NEGLIGIBLE.
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o CF MAY NOT PREVENT CORE MELT AND VESSEL FAILURE.
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SUPNARY:
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o MP1 E0Ps MININIZE CONDITIONS UNDER WHICH CONTAllMENT FLOODING IS REQUIRED.
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o THEREFORE, RPV AND DW VENTING IS NOT REQUIRED FOR THESE ACCIDENTS.
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2. DERGENCY RPV DEPRESSURIZATION (DEP)
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o DEP REQUIRES INITIATING IC (IF NOT ALREADY IN SERVICE) ale OPENING 4 SRVs, RESULTING IN A SUBSTANTIAL LOSS OF RPV INVENT 0RY.
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o DEP IS PERFORMED:
i0 ALLOW LOW PRESSURE INJECTION
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TO TEMPORARILY COOL FUEL IN STEAM
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C0OLING (CONTINGENCY #3)
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TO REDUCE ENERGY IN THE RPV WHEN A
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CONTAIMENT LIMIT IS REACHED p
TO REDUCE UNIS0LABLE RPV LEAKS IN THE
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REACTOR BUILDING TO REDUCE RADI0 ACTIVITY RELEASE INTO THE
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REACTOR BUILDING OR AREAS EXTERNAL TO IT.
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W1 E0P.. CRITERIA:
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IN AN ATWS - NO DEVIATION.
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IN-A NON-ATWS - nelEN A CONDITION IS MET.
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Open 4 l-availablel SRVs.
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No Deviation i
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not open Open 4 SRVs
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l SRVs until when lovel drops i
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"l 2/3 core height ai be L
Deviation Plant specific valuo used.
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TO PUT THE ISSUE INTO PERSPECTIVE:
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IS STATION AC BLACK 0UT.
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WE 00 NOT EXPECT THE EPG LIMITS FOR DEP TO BE
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EXCEEDED IN MOST STATION AC BLACK 0UT SCENARIOS.
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CONCERN WITH EPG APPRGACH:
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o DEP IS PERFORMED IRRESPECTIVE OF THE STATUS OF INJECTION SOURCE FOR THE RPV.
o IF IC IS IN OPERATION, DEP COULD CHANGE A STABLE CONDITION INTO AN EVENT WERE FUEL DAMAGE OCCURS.
o DEP DOES NOT HELP CONTAll#4ENT, AS IT ADDS HEAT TO I.
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BASIS FOR MP1 E0P APPRGACH:
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SIMILAR TO ADS LOGIC.
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o AS IN THE EPGs, MP1 E0Ps GIVE PREFERENCE TO THE CONTAIMENT OVER THE CORE.
DIFFERENCE LIES IN
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i CREDITING REALISTIC LIMITS OF THE CONTAINMENT.
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o IF IC IS IN SERVICE, CONTAIMENT INTEGRITY IS NOT THREATENED (I.E., REALISTIC LIMITS WILL NOT BE APPROACHED).
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o BECAUSE OF THE ENERGY ADDITION TO THE CONTAINMENT, PERFORMING DEP DOES NOT HELP THE CONTAINMENT.
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REALISTIC LIMITS FOR W 1.CONTAI MENT
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E REALISTIC EPG C0mITION LIMIT FOR PARAMETER REQUIRING.DEP MP1 CONTAINMENT CONTAIMENT PRESSURE 35 PSIG (PSP)
> 100 PSIG
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i DW TEWERATURE 281 F
> 5500F l
205 F (HCTL)
> 3300F
TORUS WATER TEMP.
TORUS WATER LEVE'
(LOW)
10.5 FT (HCLL)
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17 FT (SRV TAIL PIPE)
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COMBUSTIBLE GAS CONCENTRATION H2 > 6% AND 02 > 5%
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o IF IC IS IN SERVICE, MP1 REALISTIC LIMITS CANNOT
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o W/0 IC AND INJECTION, REALISTIC LIMITS ARE EXPECTED TO BE APPROACHED ONLY AFTER FUEL AND
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VESSEL FAILURE.
o NOT PERFORMING DEP AT THE EPG LIMIT DOES NOT RESULT IN CONTAINMENT FAILURE.
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L EFFECT OF A DEP ON THE CONTAIMENT-
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SINCE DEP INVOLVES OPENING THE SRVs, THIS ACTION WILL ALWAYS INCREASE THE TORUS TEMPERATURE AND i
CONTAI MENT PRESSURE.
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o DEPRESSURIZATION FROM 1100 PSIG TO 50 PSIG j
INCREASES:
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TORUS WATER TEMPERATURE BY AT LEAST 12 F l
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CONTAI MENT PRESSURE APPROX. 5 PSI t
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o ACTION OF DEP ITSELF DOES NOT HELP THE l
CONTAIMENT.
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RESULTS.0F STATION.AC BLACKQllI:
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INITIAL RPV LEVEL-NORMAL.
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o IC STARTS AUTOMATICALLY.
CASE A:
IC IS USED TO MAINTAIN PRESSURE AT 900 PSIG.
MINIMUM RPV LEVEL = 100" ABOVE TAF l
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CASE B:
IC DEPRESSURIZES THE RPV TO 50 PSIG MINIMUM RPV LEVEL = 35" AB0VE TAF
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CASE C:
IC AND 4 SRVs DEPRESSURIZE THE RPV TO 50 PSIG.
MINIMUN RPV LEVEL = 77" BELOW TAF Sutt E :
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EPG APPROACH RESULTS IN CORE UNC0VERY AND POSSIBLE FUEL DAMAGE AND ADDS HEAT TO THE CONTAINMENT.
MP1 E0P i
APPROACH MAINTAINS LEVEL > TAF WITH NO CORE DAMAGE.
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INVESTIGATION OF THE EPG LIMIIS
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EPG REQUIREMENT TO PERFORM DEP WHEN DW
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(DW TEMPERATURE REACHES 281 F
600 SECS WITH 0.01 FT2 BREAK
> 4 HOURS IN A STATION AC BLACK 0UT)
BASIS FOR EPG REQUIREMENT:
LOWER OF:
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DW DESIGN TEMPERATURE.
1.
L 2.
SRV QUALIFICATION TEMPERATURE.
l MP1 EVALUATION:
!
o DW FAILURE IS NOT EXPECTED AT 281 F.
REALISTIC
LIMIT > 550 F, o
LIMIT SET BY SRV QUALIFICATION AND NOT CONTAINMENT
'
FAILURE.
o RPV CAN BE DEPRESSURIZED WITH THE IC EVEN IF THE SRVs FAIL.
S1HERY:
PERFORMING DEP WHEN DW TEMPERATURE EXCEEDS 281 F IS NOT JUSTIFIED IF SUCH AN ACTION COULD RESULT IN FUEL DAMAGE (E.s., NO INJECTION IS AVAILABLE TO MAKE UP FOR LOSS IN INVENTORY).
-
.
_
... -...,,
-.~ w..
.
.
.
_-
- - - -
_. - - - - - - - - - - - _ - - -..
.
.-
.
.
2.
EPG REQUIREMENT TO PERFORM DEP WEN TORUS LEVEL IS
"
i BELOW THE ELEVATION 0F DOWNCOMER (10.5 FT.)
TORUS LEVEL < 10.5 FT (3 FT BELOW NORMAL) CAN
'
OCCUR ONLY IF THERE IS A BREACH IN THE TORUS.
BASIS FOR.EPG REQUIREMENT:
.
SUPPRESSION OF STEAM IN CASE OF LOCA IS NOT-ASSURED
'
WHEN DOWNCOMERS ARE UNC0VERED.
,
MP1 EVALUATION:
>
l
o TORUS LEVEL < 10.5 FT. IMPLIES A BREACH IN THE
-
CONTAI MENT, S0 ACTION DOES NOT PRESERVE l
l CONTAIMENT B0UNDARY.
o PROBABILITY OF A LOCA AFTER A LOSS OF ALL INJECTIONISNgGLIGIBLE.
(FREQUENCY OF A LOCA = 3 X 10
/ DAY).
'
.
o LIKELIHOOD OF FUEL DAMAGE FOLLOWING A DEP (WITH NO INJECTION) IS HIGH.
f
--
, -..
.
, -..... -,.
_.. _, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. _ _ _ _ _ _ _ _ _ _ _. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
...
_ _. _ _
_
._ _ _ _ _... _ _ _ ____ _ _. _ __.__. _. _. _
t
.
.
,. -,
l
..
-
+
SUMARY:
'
,
e o
IF THERE WERE NO RISK 0F FUEL DAMAGE, DEP WOULD
[
BE JUSTIFIED.
!
,
.
o SINCE THERE IS A SIGNIFICANT RISK OF FUEL DAMAGE, DEP IS NOT JUSTIFIED, ESPECIALLY WHEN THE
+
CONTAIMENT IS ALREADY BREACHED,
.
'
o SINCE THE CONTAI MENT IS ALREADY BREACHED, NUMBER ONE PRIORITY SHOULD BE CORE INTEGRITY.
'
l l
t
>
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!
i L
L:
-.
.
.- -
.
g 4.
I
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.
.
.
3.
EPG REQUIREMENT TO PERFORM DEP WHEN THE HEAT
-
CAPACITY TEWERATURE LIMIT (HCTL) IS EXCEEDED
'#
- p..
. n,.
g.:n.
( 260
1240 m
.
~
L
^
'
- --
,,,
220
'
~
m w
,,,,
\\\\
' ' "
200 190
% 10.5
200 400 000 000 1000 1200 RPV Pressure (polg)
Heat capachy Temperature Lima (NOT LIKELY TO BE REACHED SINCE IC IS IN SERVICE TO REMOVE ALL DECAY HEAT)
BASIS FOR EPG REQUIREMENT:
NIGHEST TORUS TEMPERATURE AT WHICH, IF DEP IS PERFORMED, CONTAllMENT TEMPERATURE WILL NOT EXCEED DESIGN TEMPERATURE AND PRESSURE WILL NOT EXCEED THE PRIMARY CONTAllNENT PRESSURE LIMIT (PCPL) BY THE TIME DECAY HEAT DROPS TO VENT CAPACITY.
.
,
,
..
..
_ _ _ _. _ _ _ _ _ _ _. _ _ _ _ _ _ _ _ _. _ _ _ _
,
~
.
'
....
.
,
..
ASSMRTIONS OF THE HCTL ANALYSIS:
-
o ALL DECAY HEAT AND BLOWOWN ENERGY IS DISCHARGED TO THE TORUS.
NO CREDIT FOR THE IC.
!
.
o NO TORUS COOLING.
o REACTOR IS SHUTDOWN FOR 2 MINUTES AT THE TIME i
r 0F DEP.
W1 EVALUATION:
l-o
- HCTL IS NOT ACCURATE WHEN IC IS IN SERVICE.
o HCTL IS NOT RELEVANT SINCE DEP IS NOT BEING j
PERFORMED.
o INITIAL CONDITIONS FOR THE HCTL ARE ARBITRARY AND UNREALISTIC.
o PERFORMING DEP WHEN IC IS IN SERVICE ONLY
>
!
INCREASES TORUS TEMPERATURE-(BY > 12 F).
o NOT PERFORMING DEP AT HCTL DOES NOT EQUATE
'
TO CONTAIMENT FAILURE.
l l
SlatBRY:
DEP AT HCTL IS NOT JUSTIFIED IF IC IS WORKING AND NO INJECTION SOURCE IS AVAILABLE.
o
!
,
'
-
.
-
..
.
. - -
- -
-. -
.
_
_. _ _ _ _ _ _... _ _ _. _ _ _ _ _ _ _ _.. _ _ _ _ _ _..
'
..
.
r z.
4.
EPG REQUIRENENT TO PERFORM DEP.WHEN
'
H 2 6% Ale 02 > 5%
v
.
BASIS FOR EPG REQUIREMENT:
.
TO PLACE THE RPV IN A LOWER STATE OF ENERGY WNEN A
L COMBUSTIBLE GAS MIXTURE EXISTS IN THE CONTAINMENT.
W1 EVALUATION:
o LIKELIHOOD 0F FUEL DAMAGE FOLLOWING A DEP
'
(WITH NO INJECTION) IS HIGH, o
PERFORMING DEP WILL NOT HELP THE CONTAINMENT.
i FUEL DAMAGE, CAUSED BY THE DEP MAY GENERATE ADDITIONAL H -
SMHMLY:
PERFORMING DEP kHEN Hg CONCENTRATION IS 2 6% AND 02 > 5% IS NOT JUSTIFIED IF SUCH AN ACTION RESULTS IN FUEL DAMAGE.
J
)
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,
.
-
_
..
I
-
_.
. - - - -
..
,
.
..
l
- -
5.
EPG REQUIREMENT TO PERFORM DEP MtEN THE PRESSURE SUPPRESSION PRESSURE (PSP) IS EXCEEDED i
I
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h k k
hY.k D,j[
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8 10 12'14 16 18'20'22 24 26
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Torus Water Level (n)
.
- Pressure Suppression Pressure
!
WITH NO INJECTION SOURCE, WHEN TORUS PRESSURE EXCEEDS
'
BASIS FOR EPG REQUIREMENT:
i o
FOR TORUS LEVEL < 18 FT, PSP IS CALCULATED ASSLMING ALL N2 FROM THE DW IS TRANSFERRED TO THE TORUS AIR SPACE,
,
o TORUS PRESSURE > PSP IMPLIES STEAM IS BEING INTRODUCED INTO TORUS AIR SPACE.
'
o DEP IS PERFORMED TO PLACE THE RPV IN A LOWER ENERGY STATE AND TO REDUCE LEAKAGE, IF ANY.
l
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.
-
.... -.... _, _ _ ~.. _ _ _ _, _
-. _. _.. -., _.. - _ _ _ - -..
-
_ _..... _ _ _.
_ _ _ _ _ _
,
4.
.
e~:
,
I
,
j MP1 EVALUATION:
-
P'
o ISOL.ATION CONDENSER CAN BE USED IN DEPRESSURIZING
-
,
'
THE RPV.
o PROBABILITY OF A LOCA FOLLOWING A STATION AC
>
BLACK 0UT Am A LOSS OF VAPOR SUPPRESSION IS
'
NEGLIGIBLE.
~
o LIKELIHOOD OF FUEL DAMAGE FOLLOWING A DEP
,
(WITH NO INJECTION) IS HIGH.
SMBRY:
l DEP AT PSP IS NOT JUSTIFIED IF NO INJECTION SOURCE IS AVAILABLE.
I
!
.
i
,
F
.
-
... - -
- -
-
.
...
_ _ _
. _ _ _. _
...
...
...
.
O
...
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,
.
3.
STEQi COOLING AT LOW PRESSURE o
RELATES TO DEVIATION #1 IDENTIFIED IN THE INTERIM EVALUATION.
o DEVIATION IDENTIFIED IS:
EPG:
REQUIRES DEP WHEN LEVEL DROPS TO TAF.
MP1 E0P:
REQUIRES DEP WHEN RPV LEVEL DROPS TO 2/3 CORE HEIGHT IF NO INJECTION SOURCE IS OPERATING AND IC IS NOT WORKING.
_
-.
..
.--
_-._..-..-..
-- - -.-.- -
.-
.-
...
.
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.
.
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COMPARISON OF EPG AND MP1 E0P STEPS
'
,
EPG STEP:
,
f
.WNEN RPV LEVEL DROPS TO TAF, AT NIGN RPV PRESSURE:
,
'
IF AN INJECTION SOURCE IS AVAILABLE, DEP
'
-
IS PERFORMED.
L IF NO INJECTION SOURCE IS AVAILABLE,
--
STEAM COOLING ~IS PERFORMED.
- .
y DEP IS PERFORMED REGARDLESS OF STATUS
'
-
L OF INJECTION SOURCES.
MP1 E0P STEP:
[
REGARDLESS OF RPV PRESSURE, WNEN LEVEL DROPS TO TAF:
+
'
IF AN INJECTION SOURCE IS AVAILABLE, DEP IS-
--
PERFORMED.
IF NO INJECTION SOURCE IS AVAILALBE, STEAM
--
COOLING IS PERFORMED.
u
. -
. - -.
.
__._._ _ __._. _.
-
. - _. _ _. _ _ - _.. _ _ _. _. -
4-
.
.-...
.
,
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,
BASIS FOR.MP1 E0P APPROACH:
'-
.,
o MP1 SPECIFIC ANALYSIS SHOWS THAT STEAM COOLING
IS EFFECTIVE AT LOW AS WELL AS HIGH PRESSURE.
l ANALYSIS RESULTS SHOW A SIGNIFICANT INCREASE IN 1140-PHASE LEVEL AT LOW PRESSURE FOR A GIVEN COLLAPSED LEVEL.
,
SUMARY:
.
o STEAM COOLING IS EFFECTIVE AT LOW PRESSURE.
o STEAM COOLING SHOULD BE PERFORMED REGARDLESS OF RPV PRESSURE.
,
L i
l-
.
.
-
_ _ _. _ _ _ _ _ _, _
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a CLAD TEMPERATURE AT llIGl! RPV PRESSURE w
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t-3600-
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,
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.
1500-
, ' ' ' * " * " " " - - - - - - ~ - -.............., - - - ~ ~ -......
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1400-
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13DQ-
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1200-
.n
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.,
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to
,
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2/3 core IIcight collapsed Level
- g-1100-
=
,
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RPV Pressure 1100 Psis.
=
.
H Two-Phase Level,
"
-
'1000-
Ft.
~
J'?
.
0 1500 sec.
-
@ 4.5 hrs.
> 8.5 Ft.
-
,,
1511 'F.-
fi Peak Clad Temp.
=
08400 sec.
f" 900-
>
[,
800-
,
(
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9j
, f<.
700-
-
.
,
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.
.
.
2000 4000 6000 0000 10000 12000 14000 16000 18000 20000 s
T111E (SEC)
p:
- Elevation-11.25 ft.
Elevation-l l. 7 5 Yt.
"
lv
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p p
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'
CLAD TE!!PERATURE' AT LOW RPV PRESSURE L
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-1200-f e
k 1100-i 2000-
.
900-
!
'
'
-
Collapsed Leve1 <= 2/3 Cote lleight
'
. w- 'B00-RPV Pressure
= 100 Psia
.
<; -
Two-Phase Level > 12 Ft.
= fu
'
'D Fuel Never lleats Up h
l 700-
-[
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!
-600-n l.
i 500'-
l 400-
..
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.
300,
.
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.
.
.
.
-
.
,
,
.
2000 4000 6000 8000 10000 12000 14000.16000 18000 20000 TI!!E (SEC)
l
-.
- -
-
- -
-
-
-
-
-
..
__
..
.
__
_.....
. _.... _ _. _ _ _ _. _ _ _.
_ _ _ _.
-. _
,
.
....
-
....
4.
EFFECTIVENESS OF ISOLATION
-
CONDENSER (IC) AT LOW PRES 10RE
L o
INITIALLY IC DEPRESSURIZES THE RPV RAPIDLY AS THE STEAM CONDENSATION RATE EXCEEDS THE STEAM PRODUCTION RATE.
,
o o
WHEN THESE TWO RATES ARE EQUAL, FURTHER DEPRESSURIZATION OCCURS SLOWLY AS THE DECAY HEAT
DROPS.
o EFFECTIVENESS OF IC AT LOW PRESSURE IS VERIFIED.
L MP1 PLANT DATA DURING HURRICANE BELLE.
--
c GE ANALYSIS FOR MP1
-
..
l h
13 % y
..
4 "}
-.
,,
"":.3. J'
MP1 EOP' APPROACH to RPV' Level Control (SIMPLIFIED)
,
-
.
. Level at TAF Initiate 10
.
m Start alternate injection system,
-
v-if needed.
.
. When watet level drops to TAF
-
!'
1r F
Yes Any Pump'
tb
,
"
Running?
>
e
>
if
'
Steam cooling s
is required.
,
1,
'. f, (
if Perform DEP
.
. If level remains below TAF,
.
'
,, "
l start all available pumps, is IC in service?
l,
. When at least one pump running, then l
e continue in this procedure.
Yes it
. If level remains below TAF, then perform the following.
1r
_
1r
'
,
Walt until an Perform DEP injection becomes when level drops
..,
f
. available
.to 2/3 core height l-l'
>
h At least One
CS Pump y
injecting?
%
J
_,,
$3 Yes tb t
t
[
Maintain RPV level Containment Flooding
.
above 1/2 core height.
is required.
D fi
. If RPV level cannot
- be maintained above 1/2 core height, then L?.
containment flooding is
required.
~
,
I e
,
- )
'
.
.,
EPG Approach to RPV Level. Control (Simplified)
'.+.I
'
-.
..
-
- Start alternate injection st;bsystems, if needed.
Yes RPV Press
>270 psig?
-(
)
%
Any Pump Yes Running?
w J
V Steam Cooling is required y
erforrn DEP
-
Perform DEP When RPV Pressure falls below 270 psig, continue isICin in this procedure service?
m Yes i
V
'U U
- If water level cannot be restored and Perform DEP Perform DEP when:
maintained above TAF, When level Containment Flooding is required drops to
. - Pressure drops below 2/3 core height 270 psig or Any containment limit
-
is reached or RPV level is unknown.
-
.___
E
.-
s
'
j;,.. e
.
CONCLUSIONS o
TECHNICAL DEVIATIONS FULLY JUSTIFIED FOR MILLSTONE UNIT 1.
o DEVIATIONS SUPPORTED BY E0P VALIDATION ON PLANT-SPECIFIC SIMULATOR.
o MILLSTONE UNIT 1 E0Ps ARE OF HIGH QUALITY.
L l
.o MILLSTONE UNIT 1 E0Ps BEST ASSURE PUBLIC HEALTH AND SAFETY.
j i
,
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.
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,
'
'
_
,