ML20024H129
| ML20024H129 | |
| Person / Time | |
|---|---|
| Issue date: | 05/16/1991 |
| From: | Holahan G Office of Nuclear Reactor Regulation |
| To: | Architzel R, Arciceri W, Arildsen J NRC |
| References | |
| NUDOCS 9105220269 | |
| Download: ML20024H129 (7) | |
Text
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UNITED STATES o
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. !0666 D,
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M AY t 6 1991 MEMORANDUM FOR:
Those on attached list FROM:
Gary Holahan, Deputy Director Division of Systems Technology Office of Nuclear Reactor Regulation
SUBJECT:
MEETING MINUTES FOR SHUTDOWN AND LOW POWER ISSVES CONFERENCE HELD ON APRIL 30 - MAY 2, 1991 During the period April 30, 1991 to May 2, 1991, a conference on shutdown and low power issues was held in Rockville, Maryland.
The purpose of the conference was to provide a forum for cognizant NRC personnel and personnel from associated national laboratories to discuss shutdown / low power issues and draw preliminary insights on tne risks associated with these issues. The discussions were based on on-going evaluations and experience in the areas of shutdown and low power risks such as AE00 operating experience reviews, NRR site visits, Regional experience from inspections and operator licensing, and RES probabilistic risk assessments.
The insights from the conference will be usea to focus future program activities on the most safety significant issues.
The final agenda covered a broad range of topics and is provided as Enclosure 1.
A composite list of participants over the three-day conference is provided in.
As a result of the discussions, preliminary insights were developed and are provided in Enclosure 3.
The insights from the conference have been broadly categorized and are provided to you for review and comment.
Your review should include any comments on the completeness of the list from conference discussions as well as any additional insights which you think are warranted as a result of reflecting on the subject of shutdown and low power 1ssues.
l All comments should be provided to Mark Caruso at (301) 492-3235 by May 24, j
1991 in order to expeditiously proceed with near term program activities, j
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Gary Holaha, Deputy Director Division of Systems Technology Office of Nuclear Reactor Regulation
Enclosures:
As stated cc: See next page 9105220269 910516 p
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t MAY t 6 1991 cc: Memorandum for those on attached list Ralph Architzel (80-1)
William Arciceri (INEL) (NL-007)
Jesse Arildsen (100-24)
Jay Ball (9A-1)
Phil Brochman (Rill)
Allen Camp (Sandia)
Mark Caruso (8E-23)
Donald Copinger (ORNL)
Mike Cullingford (12G-18)
Mark Cunningham (NLS-372)
KulinDesai(8E-23)
Paul Doyle (100-22)
Daniel Gallagher (SAIC)
Nanette Gilles (11E-22)
Anthony Gody, Jr. (13E-21)
Pete Habighorst (RI)
Gary Holahan (8E-2)
Kahtan Jabbour (9H-3)
Jim Knight (7E-4)
Lawrence Kokajko (13E-16)
Jack Kudrick (80-1)
George Lanik (AE00)
Bill Lazarus (RI)
Melvyn Leach (Rlll)
Jim Lazevnick (7E-4)
Warren Lyon (8E-23)
FredManning(AE00)
George Minarick (SAIC)
Robert Perch (8H-3)
William Raymond (RI)
Mark Reinhart (11E-24)
Howard Richings (8E-23)
Richard Robinson (NLS-272)
Faust Rosa (7E-4)
Bob Samworth (13E-21)
Susan Shankman (10D-24)
Warren Swenson (13E-4)
NormanWagner(8D-1)
Len Ward (INEL) (NL-007)
Millard Wohl (11F-23)
Ashok Thadani (8E-2)
William Russell (12G-18)
Thomas Novak, AE0D (MNBB-3701)
Jack Rosenthal, AE0D (MNBB-9715)
Samuel Collins (Region IV)
NRR Division Directors Central Files (P1-37)
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- '). - c Lt ENCLOSURE 1 s'
FINAL-AGENDA CONFERFNCE ON SPUTDOWN AND LOW POWER ISSUES PROPOSED DISCUSSION DATE
-SESSION-SUBJECT LEADER 4/30 8:15 AM Opening Remarks Gary Holahan, NRR 8:30 AM Presentction on RES RES, BNL, SNL PRA Studies 9:00 AM_
_ Presentation on AEOD AEOD Review of Operating Experience 9:30 AM.
PWR Loss of Decay Heat Warren Lyon, NRR Removal and LOCA 4/30-A"ternoon ISLOCA SamDiab,if,R
.BWR Loss of Decay Heat Tim Collins, NRR
. Removal and LOCA
-5/1:
Morning
' Safety Assessment in Warren Lyon, NRR
-Outage Planning and Management 5/1 Afternoon-Boron Dilution Howard Richings, NRR SWR Fuel Misload Howard Richings, NRR L
-Heavy Loads /-
Ralph Architzel, NRR l
Fuel Handling o
- 5/2 Morning Availability of.
Jim Knight, NRR Electric Power Containment Design Jack Kudrick, NRR and Closure Procedures 5/21
- Afternoon
. Discussion of Overall Gary Holahan
. Insights and Program Direction l
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i ENCLOSURE 2 CONFERENCE ATTENDEES SHUTDOWN AND LOW POWER ISSVES APRIL 30 - MAY 2, 1991 NAME ORGANIZATION Ralph Architzel NRR William Arciceri INEL Jesse Arildsen NRR Jay Ball NRR Phil Brochman Region Ill
-Allen Camp Sandia Mark Caruso NRR Nilesh Chokshi RES Donald Copinger ORNL Mike Cullingford NRR Mark Cunningham RES Kulin Desai NRR Paul Doyle NRR Bob Fitzpatrick BNL Daniel Gallagher SAIC Nanette Gilles NRR Anthony Gody, Jr.
NRR Pete Habighorst Region I Gary Holahan NRR-Kahtan Jabbour NRR Ronaldo Jenkins NRR Jim Knight NRR Lawrence Kokajko NRR Jack Kudrick NRR George Lanik AE0D Bill Lazarus-Region 1 Melvyn Leach Region III Jim Lazevnick NRR L
Warren Lyon NRR
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Fred Manning AE00 George Minarick SAIC Robert Perch NRR Marie Pohida NRR William Raymond Region-I Mark Reinhart NRR-Howard Richings NRR Richard Robinson RES Faust Rosa NRR-Bob Samworth NRR Susan -Shan kman NRR Warren Swenson NRR Norman Wagner NRR Len Ward _
INEL Miilard Wohl NRR n.
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o ENCLOSURE 3 s
INSIGHTS FROM CONFERENCE ON SHUTOOWN AND LOW POWER ISSUES OUTAGE PLANNING AND CONTROL
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A.
GENERAL Outage planning and control may be the most significant elements of shutdown and low power risk.
All utility personnel and programs are stressed during shutdown operations:
Operations Engineering Maintenance Emergency Planning Security RAD Protection Industrial Safety Contractor controls and training during shutdown is inconsistent (particularly for new individuals).
In general, the emergency planning programs have not considered the special circumstances and problems encountered during shutdown (e.g.,
evacuation of workers, ability of TSC and others to deal with complex configurations).
The effect of outage activities on operating units on the same site (e.g., shared sysicms, wrong unit).
Forced outages get less planning but involve fewer and less complex activities.
Rate of loss of a/c power to safety busses has been much greater during shutdown than during power operations.
Fuel handling and heavy loads do not appear to be significant shutdown risk issues.
B OPERATIONS Operators have less control of activities and plant conditions during shutdown than during power operations.
Entering and maintaining PWR mid-loop operation is a significant vulnerability.
Operator actions are generally more necessary for events that occur during shutdown operation than for events initiating during power operation, t.
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2-Response procedures are weak.
Not specifically developed for shutdown operations.. '_ _
Incomplete /not symptom oriented.
For additional study - effects on plant staff of:
Overtime during outages Changing shift rotations Rapidly changing plant configuration Accomodating to shutdown activities Operator Training NRC operator exams generally do not cover shutdown conditions.
Simulators generally don't cover shutdown conditions.
Technical Specifications Plant modes in Tech Specs don't correspond to risk significant operating condition (e.g., PWR mid-loop, defueled).
Shutdown mode T/Ss can be confusing and don't consistently establish minimum requirements.
Some plant-specific TSs have no requirements on electrical power systems during shutdown.
STS typically only require one division of electrical power sources (1 EDG,1 offsite,1 battery,1 ac distribution system, 1 DC bus, 2 vital ac buses from inverters) regardless of ' cad requirements (Modes 4 and 5 for BWRs, Modes 5 and 6 for PhRsb II. HARDWARE / DESIGN Shutdown instrumentation is not designed for shutdown conditions Operators have reduced confidence in instruments Availability problems Inappropriate ranges Instruments not well understood Core temperature often not monitored Demands on equipment during various modes / configurations not always consistent with the design of the equipment (e.g., LPCI/RHR).
BWRs generally have more water available during shutdown.
Injection sources Higher level in vessel
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. BWR Mark I and IIs have no " containment" capability)during refueling (i.e., only limited " confinement" capability exists.
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PWRandBWRMarkIIIcontainmentsmaybecapableofcontaidjngshut-down accidents if appropriate plans and procedures are available.
PWR containment integrity may be important during mid-loop operation.
ECCS recirculation capability may be reduced or lost by intentional sump isolation (i.e., coverage to prevent debris entry) or by foreign material in containment during shutdown.
PWR upper internals may inhibit water from entering the core from the refueling cavity.
BWR loss of DHR is less significant than PWR loss of DHR.
For additional study - Containment performance during accidents initiated from shutdown.
For additional study - Role of secondary containment in shutdown accidents.
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