Nonconservatism in Low-Temperature Overpressure Protection for Pressurized-Water Reactors| ML031070245 |
| Person / Time |
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| Site: |
Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane  |
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| Issue date: |
07/26/1993 |
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| From: |
Grimes B
Office of Nuclear Reactor Regulation |
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| To: |
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| References |
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| IN-93-058, NUDOCS 9307190131 |
| Download: ML031070245 (9) |
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Similar Documents at Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane |
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Category:NRC Information Notice
[Table view]The following query condition could not be considered due to this wiki's restrictions on query size or depth: <code> [[:Beaver Valley]] OR [[:Millstone]] OR [[:Hatch]] OR [[:Monticello]] OR [[:Calvert Cliffs]] OR [[:Dresden]] OR [[:Davis Besse]] OR [[:Peach Bottom]] OR [[:Browns Ferry]] OR [[:Salem]] OR [[:Oconee]] OR [[:Mcguire]] OR [[:Nine Mile Point]] OR [[:Palisades]] OR [[:Palo Verde]] OR [[:Perry]] OR [[:Indian Point]] OR [[:Fermi]] OR [[:Kewaunee]] OR [[:Catawba]] OR [[:Harris]] OR [[:Wolf Creek]] OR [[:Saint Lucie]] OR [[:Point Beach]] OR [[:Oyster Creek]] OR [[:Watts Bar]] OR [[:Hope Creek]] OR [[:Grand Gulf]] OR [[:Cooper]] OR [[:Sequoyah]] OR [[:Byron]] OR [[:Pilgrim]] OR [[:Arkansas Nuclear]] OR [[:Braidwood]] OR [[:Susquehanna]] OR [[:Summer]] OR [[:Prairie Island]] OR [[:Columbia]] OR [[:Seabrook]] OR [[:Brunswick]] OR [[:Surry]] OR [[:Limerick]] OR [[:North Anna]] OR [[:Turkey Point]] OR [[:River Bend]] OR [[:Vermont Yankee]] OR [[:Crystal River]] OR [[:Haddam Neck]] OR [[:Ginna]] OR [[:Diablo Canyon]] OR [[:Callaway]] OR [[:Vogtle]] OR [[:Waterford]] OR [[:Duane Arnold]] OR [[:Farley]] OR [[:Robinson]] OR [[:Clinton]] OR [[:South Texas]] OR [[:San Onofre]] OR [[:Cook]] OR [[:Comanche Peak]] OR [[:Yankee Rowe]] OR [[:Maine Yankee]] OR [[:Quad Cities]] OR [[:Humboldt Bay]] OR [[:La Crosse]] OR [[:Big Rock Point]] OR [[:Rancho Seco]] OR [[:Zion]] OR [[:Midland]] OR [[:Bellefonte]] OR [[:Fort Calhoun]] OR [[:FitzPatrick]] OR [[:McGuire]] OR [[:LaSalle]] OR [[:Fort Saint Vrain]] OR [[:Shoreham]] OR [[:Satsop]] OR [[:Trojan]] OR [[:Atlantic Nuclear Power Plant]] OR [[:Crane]] </code>. |
- UNITED STATES NUCLEAR REGULATORY
COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555 July 26, 1993 NRC INFORMATION
NOTICE 93-58: NONCONSERVATISM
IN LOW-TEMPERATURE
OVERPRESSURE
PROTECTION
FOR PRESSURIZED-WATER
REACTORS
Addressees
All holders of operating
licenses or construction
permits for pressurized- water reactors.,
Purpose
The U.S. Nuclear Regulatory
Commission (NRC) is issuing this information
notice to alert addressees
to a nonconservatism
in the low-temperature
overpressure
protection (LTOP) setpoint calculation
for Westinghouse
facilities.
It is expected that recipients
will review the information
for applicability
to their facilities
and consider actions, as appropriate, to avoid similar problems.
However, suggestions
contained
in this information
notice are not NRC requirements;
therefore, no specific action or written response is required.Description
of Circumstance
On October 29, 1992, the Texas Utilities
Electric Company, the licensee for Comanche Peak Steam Electric Station, reported that its existing low temperature
overpressure
protection
may not have provided the required margins of safety against reactor vessel brittle fracture under certain overpressure
transients.
The same concern was later reported by the licensees
for Byron, Zion, Diablo Canyon, Kewaunee, Sequoyah and Point Beach nuclear stations.Discussion
In reactor units designed by Westinghouse, overpressure
protection
of the reactor vessel at low temperature
conditions
is provided by a cold overpressure
mitigation
system (COMS). This system compares pressure and temperature
inputs against a preset setpoint curve and relieves the pressure when the setpoint is reached. This protection
is necessary
because, while at low temperatures
during plant startup and shutdown conditions, certain transients
could cause the reactor coolant system pressure to exceed the reactor vessel pressure-temperature (P-7) limitations
established
for protection
against brittle fracture.
A spurious start of a safety injection pump, reactor coolant pump, or other operational
errors could activate this system. During such events, the P-T limitations
are maintained
by opening the pressurizer
power-operated
relief valves (PORVs) or safety relief valves in the residual heat removal (RHR) suction lines to relieve system pressure.9307190131 RD3 -R
IN 93-58 July 26, 1993 The transmitters
that provide pressure signals to the COMS are located at the primary system hot leg piping of the reactor vessel. During low temperature
operation
of the reactor coolant pumps, dynamic pressure in the reactor vessel would be higher (by the amount of flow loss in the core and vessel outlet)than that sensed in the hot leg. Additionally, the static head correction
for the difference
in elevation
of the sensor to the core region was not considered.
The resulting
pressure difference
between the sensor and the vulnerable
location in the reactor vessel could be as high as 790 kPa (100 psig), depending
on the number of reactor coolant pumps in operation
and the location of the pressure-sensing
taps. The LTOP setpoint curve that was originally
developed
by Westinghouse
did not take these factors into consideration.
Westinghouse
has sent a letter to licensees
recommending
one of the following methods to compensate
for this pressure increase:
1) reduce the maximum allowable
relief valve setpoint by an amount equivalent
to the plant-specific
calculated
difference
in pressure, 2) maintain RCS pressure below the heatup/cooldown
curves by a value equal to the plant specific difference
in pressure from both flow loss and elevation
difference
when the reactor coolant pumps are in operation, 3) restrict the number of reactor coolant pumps and, therefore, the flow loss error that can be operated below a defined RCS temperature
without drawing a steam bubble in the pressurizer, or 4)demonstrate
that the available
margin in the LTOP calculation, taking into account instrumentation
uncertainty, is sufficient
to offset the plant-specific pressure difference.
The Westinghouse
letter describes
interim administrative
controls as well as calculational
methods to verify setpoint adequacy for addressing
the LTOP concern. The staff notes that the administrative
restrictions
described
in approaches
(2) and (3) are intended by Westinghouse
to provide interim actions to address the concern only until LTOP setpoints
are verified to be adequate or are revised appropriately
in technical
specifications.
Although the information
in this notice addresses
the cold overpressure
mitigation
system at Westinghouse
designed plants, aspects of this issue may also be applicable
to other PWRs.
r
- s IN 93-58 July 26, 1993 This information
notice requires no specific action or written response.
If you have any questions
about the information
in this notice, please contact one of the technical
contacts listed below or the appropriate
Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts:
Thomas Koshy (301) 504-1176 Chu-Yu Hang (301) 504-2878 Attachment:
List of Recently Issued NRC Information
Notices
.t Attachment
IN 93-58 July 26. IM Page I of I LIST OF RECENTLY ISSUED NRC INFORMATION
NOTICES Information
Date of Notice No. Subject Issuance Issued to 93-57 Software Problems 07/23/93 All holders of OLs or CPs Involving
Digital for test and research Control Console Systems reactors and nuclear power at Non-Power
Reactors reactors 93-56 Weakness in Emergency
07/22/93 All holders of OLs or CPs Operating
Procedures
for pressurized
water Found as Result of reactors.Steam generator
Tube Rupture 93-55 Potential
Problem with 07/21/93 All holders of OLs or CPs Main Steamline
Break for pressurized
water Analysis for Main Steam reactors.Vaults/Tunnels
93-54 Motor-Operated
Valve 07/20/93 All holders of OLs or CPs Actuator Thrust for nuclear power reactors.Variations
Measured with A Torque Thrust Cell and A Strain Gage 93-53 Effect of Hurricane
07/20/93 All holders of OLs or CPs Andrew on Turkey Point for nuclear power reactors.Nuclear Generating
Station and Lessons Learned 93-52 Draft NUREG-1477, 07/14/93 All holders of OLs or CPs'Voltage-Based
Interim for pressurized
water Plugging Criteria for reactor (PWRs).Steam Generator
Tubes'93-51 Repetitive
Overspeed
07/09/93 All holders of OLs or CPs Tripping of Turbine- for nuclear power reactors.Driven Auxiliary
Feed-water Pumps 93-50 Extended Storage of 07/08/93 All licensees
authorized
Sealed Sources to possess sealed sources.OL -Operating
License CP -Construction
Permit 0 4>us 0) .(I)0 0.2 0 _2 t o Lno 0 o, W U 2C cc CO 0 LU.)8 co Z UJ_ 4 A3>Z. i-i1X o z w 0.
IN 93-58 July 26, 1993 This information
notice requires no specific action or written response.
If you have any questions
about the information
in this notice, please contact one of the technical
contacts listed below or the appropriate
Office of Nuclear Reactor Regulation (NRR) project manager.Ordginal sgnei by Brian IL. W=me Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: Thomas Koshy (301) 504-1176 Chu-Yu Liang (301) 504-2878 Attachment:
List of Recently Issued NRC Information
Notices*See previous concurrence
OFC OEAB:DORS
ADM:PUB SC/OEAB:DORS
C/SRXB:DSSA
NAME TKoshy* Tech Editor* EGoodwin*
RJones*l DATE 06/04/93 05/10/93 05/21/93 06/04/93 I OFC C/EMCB:DE
C/OEAB:DORS
OGCB:DORS
C/OGCB:DORS
NAME l JStrosnider*
AChaffee*
JLBirmingham*
GHMarcus*DATE 05/24/931
06/08/93 06/17/93 06/17/93[OFC 1 __ __ ClNAME W ameslDATE 07/-vf/93[OFFICIAL
RECORD COPY]DOCUMENT NAME: S:\DORSSEC\93-58.IN
emw& aA Iq 1A~k~AM'x$& d.1'r- .a4 4k, kxd).'_ ..-.,ng ?w ar sL*K e4W 4._ _71Z11l9 3 IN 93-XX June xx, 1993 This information
notice requires no specific action or written response.
If you have any questions
about the information
in this notice, please contact one of the technical
contacts listed below or the appropriate
Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Reactor Support Office of Nuclear Reactor Regulation
Technical
contacts: Thomas Koshy (301) 504-1176 Chu-Yu Liang (301) 504-2878 Attachment:
List of Recently Issued NRC Information
Notices*See previous concurrence
OFC OEAB:DORS
ADM:PUB l SC/OEAB:DORS
C/SRXB:DSSA
l NAME TKoshy* Tech Editor* EGoodwin*
RJones* lDATE l 06/04/93 l 05/10/93 l 05/21/93 06/04/93 l[ OFC l C/EMCB:DE
C/OEAB:DORS
OGCB:DOR Ltj C/OGCB:DORS
lNAME JStrosnider*
AChaffee*
JLBirmingam
HMarcus L DATE 05/24/93 06/08/93 06/16/93 06/ 7/93l OFC D/:DORS l l l _ _NAME BKGrimes l DATE 06/ /93 _ l[OFFICIAL
RECORD COPY]DOCUMENT NAME: S:\DO RS SEC\LTOPREV1.IN
OFC OEAB:DORS
ADM:PUB SC/OEAB:DORS
C/SRXB:DSSA
NAME TKoshy A- Tech Editor* EGoodwin*
RJones*DATE 6 4 /93 05/10/93 05/21/93 06/04/93[OFC C/EMCB:DE
C/OEAB:DORS
C/OGCB:DORS
D/DORS NAME JStrosnider*
AChaffee*
GMarcus BGrlimes DATE 05/24/93 1 06/08/93 / /93 / /93[OFFICIAL
RECORD COPY]DOCUMENT NAME: S:\DORSSEC\LTOP.IN
[OFC OEAB:DORS
ADM:PUB SC/OEAB:DORS
C/SRXB:D S l NAME TKoshy Tech Editor* EGoodwin*
RJones /DATE 60 /zI/93 05/10/93 05/21/93 1 y/93 OFC C/EMCB:DE
C/OEAB:WDORS
C/OGCB:DORS
D/DORS NAME JStrosnider*
A ee GMarcus BGrimes DATE 105/24/93 j 0 / 6 /93 J / /93 j[OFFICIAL
RECORD COPY]DOCUMENT NAME: G:\TXK\LTOP.IN
OFC OEAB:DORS
ADM:PUB SC/OEAB:DORS
C/SRXB:DSSA
, NAME TKoshy & Tech Editor* EGoodwin RJones DATE 05/tQ/93 05/10/93 05/ l93 e e 193 I[OFC _ C/EMCB:DE
C/OEAB:DORS
C/OGCB:DORS
D/DORS NAME JStrosnide
I AChaffee GMarcus BGrimes DATE 05/24/93 05/ /93 05/ /93 05/ J93[OFFICIAL
RECORD COPY]DOCUMENT NAME: G:\TXK\LTOP.IN
d. I-
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| list | - Information Notice 1993-01, Accuracy of Motor-Operated Valve Diagnostic Equipment Manufactured by Liberty Technologies (4 January 1993)
- Information Notice 1993-02, Malfunction of a Pressurizer Code Safety Valve (4 January 1993, Topic: Loop seal)
- Information Notice 1993-04, Investigation and Reporting of Misadministrations by the Radiation Safety Officer (7 January 1993, Topic: Uranium Hexafluoride, Overexposure)
- Information Notice 1993-05, Locking of Radiography Exposure Devices (14 January 1993, Topic: Uranium Hexafluoride, Inattentive)
- Information Notice 1993-06, Potential Bypass Leakage Paths Around Filters Installed in Ventilation Systems (22 January 1993)
- Information Notice 1993-07, Classification of Transportation Emergencies (1 February 1993)
- Information Notice 1993-08, Failure of Residual Heat Removal Pump Bearings Due to High Thrust Loading (1 February 1993, Topic: Probabilistic Risk Assessment)
- Information Notice 1993-09, Failure of Undervoltage Trip Attachment on Westinghouse Model DB-50 Reactor Trip Breaker (2 February 1993, Topic: Commercial Grade)
- Information Notice 1993-10, Dose Calibrator Quality Control (2 February 1993, Topic: Uranium Hexafluoride)
- Information Notice 1993-11, Single Failure Vulnerability of Engineered Safety Features Actuation Systems (4 February 1993)
- Information Notice 1993-12, Off-Gassing in Auxiliary Feedwater System Raw Water Sources (11 February 1993)
- Information Notice 1993-13, Undetected Modification of Flow Characteristics in High Pressure Safety Injection System (16 February 1993)
- Information Notice 1993-14, Clarification of 10 CFR 40.22, Small Quantities of Source Material (18 February 1993)
- Information Notice 1993-15, Failure to Verify the Continuity of Shunt Trip Attachment Contacts in Manual Safety Injection and Reactor Trip Switches (18 February 1993)
- Information Notice 1993-16, Failures of Not-Locking Devices in Check Valves (19 February 1993, Topic: Anchor Darling, Flow Induced Vibration)
- Information Notice 1993-17, Safety Systems Response to Loss of Coolant and Loss of Offsite Power (25 March 1994, Topic: Loss of Offsite Power, Backfit, Water hammer)
- Information Notice 1993-18, Portable Moisture-Density Gauge User Responsibilities During Field Operations (10 March 1993, Topic: Moisture Density Gauge, Moisture-Density Gauge, Stolen)
- Information Notice 1993-19, Slab Hopper Bulging (17 March 1993, Topic: Hydrostatic)
- Information Notice 1993-20, Thermal Fatigue Cracking of Feedwater Piping to Steam Generators (24 March 1993, Topic: Thermal fatigue)
- Information Notice 1993-21, Summary of NRC Staff Observations Compiled During Engineering Audits or Inspections of Licensee Erosion/Corrosion Programs (25 March 1993, Topic: Weld Overlay, Reactive Inspection)
- Information Notice 1993-22, Tripping of Klockner-Moeller Molded-Case Circuit Breakers Due to Support Lever Failure (26 March 1993, Topic: Commercial Grade)
- Information Notice 1993-23, Weschler Instruments Model 252 Switchboard Meters (31 March 1993, Topic: Commercial Grade)
- Information Notice 1993-24, Distribution of Revision 7 of NUREG-1021, Operation Licensing Examiner Standards (31 March 1993, Topic: Job Performance Measure)
- Information Notice 1993-25, Electrical Penetration Assembly Degradation (1 April 1993)
- Information Notice 1993-26, Grease Soldification Causes Molded-Case Circuit Breaker Failure to Close (31 January 1994)
- Information Notice 1993-27, Level Instrumentation Inaccuracies Observed During Normal Plant Depressurization (8 April 1993, Topic: Reactor Vessel Water Level)
- Information Notice 1993-28, Failure to Consider Loss of DC Bus in the Emergency Core Cooling System Evaluation May Lead to Nonconservative Analysis (9 April 1993, Topic: Loss of Offsite Power, Fuel cladding)
- Information Notice 1993-29, Problems with the Use of Unshielded Test Leads in Reactor Protection System Circuitry (12 April 1993)
- Information Notice 1993-30, NRC Requirements for Evaluation of Wipe Test Results; Calibration of Count Rate Survey Instruments (12 April 1993)
- Information Notice 1993-31, Training of Nurses Responsible for the Care of Patients with Brachytherapy Implants (13 April 1993, Topic: Brachytherapy)
- Information Notice 1993-32, Nonconservative Inputs for Boron Dilution Events Analysis (21 April 1993, Topic: Shutdown Margin)
- Information Notice 1993-33, Potential Deficiency of Certain Class Ie Instrumental and Control Cables (28 April 1993)
- Information Notice 1993-33, Potential Deficiency of Certain Class IE Instrumental and Control Cables (28 April 1993)
- Information Notice 1993-34, Potential for Loss of Emergency Cooling Function Due to a Combination of Operational and Post-LOCA Debris in Containment (6 May 1993, Topic: Brachytherapy)
- Information Notice 1993-35, Insights from Common-Cause Failure Events (12 May 1993, Topic: Probabilistic Risk Assessment)
- Information Notice 1993-36, Notifications, Reports, and Records of Misadministrations (7 May 1993, Topic: Brachytherapy)
- Information Notice 1993-37, Eyebolts with Indeterminate Properties Installed in Limitorque Valve Operator Housing Covers (19 May 1993)
- Information Notice 1993-38, Inadequate Testing of Engineered Safety Features Actuation Systems (24 May 1993)
- Information Notice 1993-39, Radiation Beams From Power Reactor Biological Shields (25 May 1993)
- Information Notice 1993-39, Radiation Beams from Power Reactor Biological Shields (25 May 1993)
- Information Notice 1993-40, Fire Endurance Test Results for Thermal Ceramics FP-60 Fire Barrier Material (26 May 1993, Topic: Safe Shutdown, Fire Barrier, Fire Protection Program)
- Information Notice 1993-41, One Hour Fire Endurance Test Results for Thermal Ceramics Kaowool, 3M Company FS-195 and 3M Company Interam E-50 Fire Barrier Systems (28 May 1993, Topic: Safe Shutdown, Fire Barrier)
- Information Notice 1993-42, Failure of Anti-Rotation Keys in Motor-Operated Valves Manufactured by Yelan (9 June 1993)
- Information Notice 1993-43, Use of Inappropriate Lubrication Oils in Satety-Related Applications (10 June 1993, Topic: Commercial Grade)
- Information Notice 1993-44, Operational Challenges During a Dual-Unit Transient (15 June 1993, Topic: Shift Technical Advisor)
- Information Notice 1993-45, Degradation of Shutdown Cooling System Performance (16 June 1993, Topic: Local Leak Rate Testing)
- Information Notice 1993-46, Potential Problem with Westinghouse Rod Control System and Inadvertent Withdrawal of Single Rod Control Cluster Assembly (10 June 1993)
- Information Notice 1993-47, Unrecognized Loss of Control Room Annunciators (18 June 1993)
- Information Notice 1993-48, Failure of Turbine-Driven Main Feedwater Pump to Trip Because of Contaminated Oil (6 July 1993, Topic: Water hammer)
- Information Notice 1993-49, Improper Integration of Software Into Operating Practices (8 July 1993)
... further results |
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