Undetected Accumulation of Gas in Reactor Coolant SystemML031060539 |
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, Three Mile Island, 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 ![Entergy icon.png](/w/images/7/79/Entergy_icon.png) |
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Issue date: |
05/24/1994 |
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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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-nr IN-94-036, NUDOCS 9405190137 |
Download: ML031060539 (10) |
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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, Three Mile Island, 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 |
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Category:NRC Information Notice
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Mclaughlin on NRC, Regarding NRC Information Notice 2006-13: Groundwater Contamination 2020-09-03 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 [[:Three Mile Island]] 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]] </code>.
[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 [[:Three Mile Island]] 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]] </code>. |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
P/-3Y
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555 May 24, 1994 NRC INFORMATION NOTICE 94-36: UNDETECTED ACCUMULATION OF GAS IN REACTOR
COOLANT SYSTEM
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to problems that could result from unrecognized
evolution and accumulation of gas in reactor coolant system high points. It
is expected that recipients will review this 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 Circumstances
Sequoyah Unit I had been shut down in March 1993. In early September 1993, after the unit had been refueled, the reactor vessel was reassembled and the
reactor coolant system was degassed, filled, and vented. The reactor coolant
system was then depressurized to atmospheric pressure. One pressurizer power- operated relief valve (PORV) was open and the reactor coolant system average
temperature was being maintained at approximately 49C [120'F]. Nitrogen
cover gas was being supplied to the volume control tank at approximately
239 kPa [20 psig] and reactor coolant was being circulated by the charging
system and the residual heat removal (RHR) system. The reactor vessel level
indication system (RVLIS) was functional for a significant portion of the
event. Before this event, instrument maintenance stickers were placed on the
RVLIS indicators for other maintenance work. Although the RVLIS information
was available, the operators were not monitoring this information because it
was not procedurally required to be used in shutdown modes of operation.
Reactor coolant system inventory was being monitored using pressurizer cold
calibration level indications.
On December 17, 1993, the operators began to pressurize the containment to
191 kPa [13 psig] in order to perform a containment integrated leak rate test.
As containment pressure increased, the operators noticed a decrease in
pressurizer water level and, over a period of time, added approximately 31,400
liters [8,300 gallons] of water to maintain the pressurizer level. Licensee
personnel evaluated this situation and recognized that gas was accumulating in
the reactor coolant system. However, they failed to recognize the magnitude
9405190137 po\ fit JEote qq-f3tn 9t1S EsoI
'I'
- ..~-IN94-36 May 24, 1994 or cause of the problem. Three days later, as the containment was being
depressurized upon completion of the containment leak test, the operators
noted that approximately the same amount of water had to be removed from the
reactor coolant system to maintain the level. On December 21, 1993, on the
basis of operators' observations of the changing coolant system Inventory
during the containment leak test, the reactor vessel head was vented. It was
subsequently vented several times to maintain appropriate reactor vessel
inventory based on RYLIS information. The reactor vessel gas voiding
conditions went undetected from early September 1993, when the reactor coolant
system was verified to be filled, until December 21, 1993, when the reactor
head was vented.
The gas evolution resulted from the temperature in the volume control tank
being much lower than that normally expected. (This lower temperature was due
to unusually low component cooling water temperatures and to a maintenance
problem with a cooling water valve that resulted in the reduction of the heat
sink temperature in the letdown heat exchanger.) The lower temperatures
increased the solubility of gas in the volume control tank water so that more
gas was dissolved in the water. This gas evolved when the water was
transferred to the reactor coolant system by the charging system and heated up
in the reactor vessel.
Further details concerning this event are in NRC Inspection Report No. 50-327;
50-328/94-04.
Discussion
The licensee completed a final evaluation in January 1994 and determined that
during this event the reactor vessel water level had decreased to slightly
below the top of the hot leg, and that the steam generator tubes were nearly
empty. The reactor coolant system inventory was being monitored solely on the
basis of pressurizer level, which was not indicative of the reactor vessel and
steam generator levels. Calculations by the licensee indicated that an
equilibrium had been reached during the event so that the water level was
approximately 1.6 meters [5.25 feet] above the top of the core. Any
additional gas evolved in the reactor vessel would be expected to be vented
through the hot leg and surge line to the pressurizer and out through the open
pressurizer PORV.
The reactor water level at which equilibrium was established at Sequoyah was
sufficiently high so as not to interfere with reactor coolant flow through the
RHR cooling system. However, at other plants, the equilibrium level, which is
related to pressurizer surge line geometry and RHR suction line location, might be such that a similar event could interfere with shutdown cooling.
Another potential safety concern is related to the capability of the steam
generators to transfer heat from the reactor coolant to secondary coolant. In
the equilibrium condition at Sequoyah, the steam generator tubes were almost
empty during at least a portion of the duration of this event. During this
IN 94-36
--JMay 24, 1994 period, the steam generators were assumed to be available as an alternate
means for shutdown cooling. It is not clear that cooling through the steam
generators could have been established, if needed, especially because the
plant operators were unaware that the tubes were empty.
Several factors involving licensee performance contributed to the delay in the
identification and evaluation of this event. They included (1) lack of
consideration on the part of licensee personnel with respect to compression of
gas in the system caused by containment pressure transmitted to the reactor
coolant system water through the open pressurizer PORV; (2) misunderstanding
by the operators about the operability of RVLIS; (3) failure to stop the
containment leak test when water level changes were first noted so that the
situation could have been adequately evaluated; (4) an apparent lack of
thorough evaluation of previously published information on similar events.
The event discussed in this information notice highlights the potential for
gas evolution and accumulation in the reactor coolant system in locations and
quantities that may not be evident to operators. Changes in temperature and
pressure can have significant effects on the solubility of gas in water, especially at or near atmospheric pressure conditions. During cold shutdown, this phenomenon can permit significant quantities of cover gas to be dissolved
in lower-temperature, higher-pressure volumes such as the volume control tank
and to evolve into a large gas bubble in the reactor vessel (a lower-pressure, higher-temperature area). This phenomenon can occur without a sudden change
in pressurizer level, which is the indicator normally used by the operators to
monitor water inventory. Use of available instrumentation in shutdown modes
to monitor reactor vessel water level can provide detection of unexpected
system conditions when reduced vessel inventory is not planned as well as in
reduced inventory evolutions.
On April 12, 1994, a similar gas accumulation event was identified at the
Salem Generating Station (Unit 1) shortly after it entered Mode 5 (cold
shutdown) operation. Although this occurrence did not involve amounts of gas
accumulation as large as in the Sequoyah event, many similarities existed
regarding both the process of gas formation and the lack of operator awareness
of the abnormal condition. In both events, reactor vessel level information
was or could have been made available for prompt identification of the
problem.
Related Generic Communications
System Raw Water Sources," discusses similar solubility
considerations related to air pockets in piping at the McGuire
Nuclear Station.
Coolant," discusses undetected loss of reactor coolant inventory
at North Anna Unit 1 resulting from inadequate use of available
indications and failure to perform mass inventory balances.
- \ >
<_IN 94-36 May 24, 1994 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 Of ice of
Nuclear Reactor Regulation (NRR) project manager.
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: R. Benedict, NRR
(301) 504-1157 S. M. Shaeffer, RII
(615) 842-8001 Attachment:
List of Recently Issued NRC Information Notices
I At,.thment
IN 94-36 May 24, 1994 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information Date of
Notice No. Subject Issuance Issued to
91-81, Switchyard Problems that 05/19/94 All holders of OLs or CPs
Supp. 1 Contribute to Loss of for nuclear power reactors.
Offsite Power
94-35 NIOSH Respirator User 05/16/94 All holders of OLs or CPs
Notices, "Inadvertent for nuclear power reactors, Separation of the Mask- and all licensed fuel
Mounted Regulator (MMR) facilities.
from the Facepiece on the
Mine Safety Appliances (MSA)
Company MMR Self-Contained
Breathing Apparatus (SCBA)
and Status Update
94-34 Thermo-Lag 330-660 05/13/94 All holders of OLs or CPs
Flexi-Blanket Ampacity for nuclear power reactors.
Derating Concerns
94-33 Capacitor Failures in 05/09/94 All holders of OLs or CPs
Westinghouse Eagle 21 for nuclear power reactors.
Plant Protection Systems
93-53, Effect of Hurricane 04/29/94 All holders of OLs or CPs
Supp. 1 Andrew on Turkey Point for nuclear power reactors.
Nuclear Generating
Station and Lessons Learned
94-32 Revised Seismic Hazard 04/29/94 All holders of OLs or CPs
Estimates for nuclear power reactors.
94-31 Potential Failure of 04/14/94 All holders of OLs or CPs
Wilco, Lexan-Type HN-4-L for nuclear power reactors.
Fire Hose Nozzles
90-68, Stress Corrosion Cracking 04/14/94 All holders of 01 or CPs
Supp. 1 of Reactor Coolant Pump for pressurized water
Bolts reactors.
94-30 Leaking Shutdown Cooling 04/12/94 All holders of OLs or CPs
Isolation Valves at for nuclear power reactors.
Cooper Nuclear Station
OL - Operating License
CP - Construction Permit
IN 94-xx
May xx, 1994 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: R. Benedict, NRR
(301) 504-1157 S. M. Shaeffer, R11
(615) 842-8001 Attachment:
List of Recently Issued NRC Information Notices
concurrence
-_. _ .
--- - 1 _._
OFFICE *OEAB:DORS *DRP:RII *OGCB:DORS *SC/DRP:RII *TECH ED
NAME RBenedict SMShaeffer PCWen MLesser MFMejac
lDATE 05/04/L94 05/05/94 05/05/94 05/05/94 05/05/94
[*AC/SRXB:DSSA *AD/DSSA *C/OEAB:DORS *AC/OGCB:DORS D/DORS
TECollins MVirgilio AChaffee AJKugler BKGrimes
05/06/94 05/09/94 05/09/94 05.12/94 / /94 DOCUMENT NAME: SLQGAbIN.KV1 NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J. Stone) have been
informed of the development of this information notice and they have
reviewed the draft information notice.
Peter Wen, 5/10/94
IN 94-xx
May xx, 1994 This information notice requires no specific action or written response.
you have any questions about the information in this notice, please contactIf
the technical contact 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: R. Benedict, NRR
(301) 504-1157 S. M. Shaeffer, RI!
(615) 842-8001 Attachment:
List of Recently Issued NRC Information Notices
OFFICE *OEAB:DORS *DRP:RII *OGCB:DORS *SC/DRP:RII *TECH ED
NAME RBenedict SMShaeffer PCWen MLesser MFMejac
DATE 05/04/94 05/05/94 05/05/94 05/05/94 05/05/94
- AC/SRXB:DSSA *AD/DSSA *C/OEAB:DORS *AC/OGCB:DORS D/DORS
TECollins 8EXI MVirgilio I AChaffee AJKugler BKGrimes
05/06/94 1 05/09/94 05/09/94 05/12/94 / /94 nnlflMFNT IAMr. eCnveCTitn .* niti
.-- -- I ia11 I EAdIL* .JLA(Un4.1 r A
NOTE: The PMs for Sequoyah (D.LaBarge) and Salem (J.Stone) have been
informed of the development of this information notice and they have
reviewed the draft information notice.
Peter Wen, 5/10/94
IN 94-xx
May xx, 1994 This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
the technical contact 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: R. Benedict, NRR
(301) 504-1157 S. M. Shaeffer, R11
(615) 842-8001 Attachment:
List of Recently Issued NRC Information Notices
See previous concurrence
OFFICE l *OEAB:DORS *DRP:RII *OGCB:DORS l *SC/DRP:RII *TECH ED
NAME } RBenedict SMShaeffer PCWen MLesser MFMejac
DATE 1 05/04/94 1_05/05/94 1 05/05/94 _ 05/05/94 1 05/05/94
- AC/SRXB:DSSA *AD/DSSA j *C/OEAB:DORS AC/OGCB:DORS D/DORS
TECollins MVirgilio AChaffee AJKugler i(: BKGrimes
05/06/94 = 05/09/94 05/09/94 5/1V94 / /94 DOCUMENT NAME: SEQGASIN.RV1 NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J. Stone) have been
informed of the development of this information notice and they have
reviewed the draft information notice.
Peter Wen, 5/10/94
IN 94-xx
May xx, 1994 This information notice requires no specific action or writttten response. If
you have any questions about the information in this notice, please contact
the technical contact 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: R. Benedict, NRR
(301) 504-1157 S. M. Shaeffer, RII
(615) 842-8001 Attachment:
List of Recently Issued NRC Information Notices
OFFICE IOEABDOR5 DRP:RIIpcyJ OGCB__ _ SC/DRP:RI TECH ED
NAME Benedict 'MShaeffer PCWen Lesser
DATE </A/94 5 /5/94 5 / 94/94 5//94 5 / 5/94 AC/SRXB:DSSA , AD/DSSA jC/OEAB:DORS AC/OGCB:DORS D/DORS
TEColli MVirgil ' A2 fe AJKugler BKGrimes
_____94
/$\/94 /947/94 94 / /94 UULUMtN I NAML: btbAbI1 N.KV1 x 01 I J//q jp'
A4Mi: THE R& FR FoY(AH (-. LAMRPE) Azb 6MPA (j. )
ROeia^ SoF'E Deospwt oF Ttts um. waIce ARD
'NW ME .F) T"E JPV OD0e bWf^ .
&4-vhiw S/o/oA4.
IN 94-36 May 24, 1994 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.
orig /s/'d by BKGrimes
Brian K. Grimes, Director
Division of Operating Reactor Support
Office of Nuclear Reactor Regulation
Technical contacts: R. Benedict, NRR
(301) 504-1157 S. M. Shaeffer, R11
(615) 842-8001 Attachment:
List of Recently Issued NRC Information Notices
E
OFFICE
NAME
RBenedict
SMShaeffer
PCWen
MLesser
MFMejac
DATE j05/04/94 05/05/94 05/05/94 05/05/94 05/05/94 l*AC/SRXB:DSSA *AD/DSSA 5*C/OEAB:DORS *AC/OGCB:DO RS*
TECollins MVirgilio AChaffee IvAJKugler _s
05/06/94 05/09/94 i 05/09/94 05/12/4 05//f/94 UuUMtrII NAMt: vq-io. IN
NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J. Stone) have been
informed of the development of this information notice and they have
reviewed the draft information notice.
Peter Wen, 5/10/94
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list | - Information Notice 1994-01, Turbine Blade Failures Caused by Torsional Excitation from Electrical System Disturbance (7 January 1994)
- Information Notice 1994-02, Inoperability of General Electric Magne-Blast Breaker Because of Misalignment of Close-Latch Spring (7 January 1994)
- Information Notice 1994-03, Deficiencies Identified During Service Water System Operational Performance Inspections (11 January 1994, Topic: Biofouling)
- Information Notice 1994-04, Digital Integrated Circuit Sockets with Intermittent Contact (14 January 1994)
- Information Notice 1994-05, Potential Failure of Steam Generator Tubes with Kinetically Welded Sleeves (19 January 1994, Topic: Stress corrosion cracking)
- Information Notice 1994-06, Potential Failure of Long-Term Emergency Nitrogen Supply for the Automatic Depressurization System Valves (28 January 1994)
- Information Notice 1994-07, Solubility Criteria for Liquid Effluent Releases to Sanitary Sewerage Under the Revised 10 CFR Part 20 (28 January 1994)
- Information Notice 1994-08, Potential for Surveillance Testing to Fail to Detect an Inoperable Main Steam Isolation Valve (1 February 1994)
- Information Notice 1994-09, Release of Patients with Residual Radioactivity from Medical Treatment & Control of Areas Due to Presence of Patients Containing Radioactivity Following Implementation of Revised 10 CFR Part 20 (3 February 1994, Topic: Brachytherapy)
- Information Notice 1994-10, Failure of Motor-Operated Valve Electric Power Train Due to Sheared or Dislodged Motor Pinion Gear Key (4 February 1994)
- Information Notice 1994-11, Turbine Overspeed and Reactor Cooldown During Shutdown Evolution (8 February 1994)
- Information Notice 1994-12, Insights Gained from Resolving Generic Issue 57: Effects of Fire Protection System Actuation on Safety-Related Equipment (9 February 1994, Topic: Overspeed trip)
- Information Notice 1994-13, Unanticipated and Unintended Movement of Fuel Assemblies and Other Components Due to Improper Operation of Refueling Equipment (28 June 1994)
- Information Notice 1994-14, Failure to Implement Requirements for Biennial Medical Examinations and Notification to the NRC of Changes in Licensed Operator Medical Conditions (24 February 1994)
- Information Notice 1994-15, Radiation Exposures During an Event Involving a Fixed Nuclear Gauge (2 March 1994)
- Information Notice 1994-16, Recent Incidents Resulting in Offsite Contamination (3 March 1994)
- Information Notice 1994-17, Strontium-90 Eye Applicators: Submission of Quality Management Plan (QMP), Calibration, and Use (11 March 1994, Topic: Brachytherapy)
- Information Notice 1994-17, Strontium-90 Eye Applicators: Submission of Quality Management Plan (Qmp), Calibration, and Use (11 March 1994, Topic: Brachytherapy)
- Information Notice 1994-18, Accuracy of Motor-Operated Valve Diagnostic Equipment (Responses to Supplement 5 to Generic Letter 89-10) (16 March 1994)
- Information Notice 1994-19, Emergency Diesel Gemerator Vulnerability to Failure from Cold Fuel Oil (16 March 1994)
- Information Notice 1994-20, Common-Cause Failures Due to Inadequate Design Control and Dedication (17 March 1994)
- Information Notice 1994-21, Regulatory Requirements When No Operations Are Being Performed (18 March 1994)
- Information Notice 1994-22, Fire Endurance & Ampacity Derating Test Results for 3-Hour Fire-Rated Thermo-Lag 330-1 Fire Barriers (16 March 1994, Topic: Fire Barrier)
- Information Notice 1994-23, Guidance to Hazardous, Radioactive and Mixed Waste Generators on the Elements of a Waste Minimization Program (25 March 1994, Topic: Fire Barrier)
- Information Notice 1994-24, Inadequate Maintenance of Uninterruptible Power Supplies & Inverters (24 March 1994, Topic: Safe Shutdown, Fire Barrier)
- Information Notice 1994-25, Failure of Containment Spray Header Valve to Open Due to Excessive Pressure from Inertial Effects of Water (15 March 1994, Topic: Fire Barrier)
- Information Notice 1994-26, Personnel Hazards and Other Problems from Smoldering Fire-Retardant Material in the Drywell of a Boiling-Water Reactor (28 March 1994, Topic: Fire Barrier)
- Information Notice 1994-27, Facility Operating Concerns Resulting from Local Area Flooding (31 March 1994, Topic: Fire Barrier)
- Information Notice 1994-28, Potential Problems with Fire-Barrier Penetration Seals (5 April 1994, Topic: Fire Barrier)
- Information Notice 1994-29, Charging Pump Trip During a Loss-of-Coolant Event Caused by Low Suction Pressure (11 April 1994, Topic: Boric Acid)
- Information Notice 1994-30, Leaking Shutdown Cooling Isolation Valves at Cooper Nuclear Station (19 August 1994, Topic: Fire Barrier)
- Information Notice 1994-31, Potential Failure of Wilco, Lexan-Type HN-4-L Fire Hose Nozzles (14 April 1994, Topic: Hydrostatic)
- Information Notice 1994-32, Revised Seismic Estimates (29 April 1994, Topic: Earthquake)
- Information Notice 1994-33, Capacitor Failures in Westinghouse Eagle 21 Plant Protection Systems (9 May 1994, Topic: Stress corrosion cracking)
- Information Notice 1994-34, Thermo-LAG 330-660 Flexi-Blanket Ampacity Derating Concerns (13 May 1994, Topic: Fire Barrier)
- Information Notice 1994-35, Niosh Respirator User Notices, Inadvertent Separation of the Mask-Mounted Regulator(Mmr) from the Facepiece on the Mine Safety Appliances (16 May 1994)
- Information Notice 1994-35, Niosh Respirator User Notices, Inadvertent Separation of the Mask-Mounted Regulator(MMR) from the Facepiece on the Mine Safety Appliances (16 May 1994)
- Information Notice 1994-36, Undetected Accumulation of Gas in Reactor Coolant System (24 May 1994, Topic: Reactor Vessel Water Level, Stress corrosion cracking, Integrated leak rate test)
- Information Notice 1994-37, Misadministration Caused by a Bent Interstitial Needle During Brachytherapy Procedure (27 May 1994, Topic: Brachytherapy)
- Information Notice 1994-38, Results of Special NRC Inspection at Dresden Nuclear Power Station, Unit 1 Following Rupture of Service Water Inside Containment (27 May 1994)
- Information Notice 1994-39, Identified Problems in Gamma Stereotactic Radiosurgery (31 May 1994)
- Information Notice 1994-40, Failure of a Rod Control Cluster Assembly to Fully Insert Following a Reactor Trip at Braidwood, Unit 2 (26 May 1994)
- Information Notice 1994-41, Problems with General Electric Type Cr124 Overload Relay Ambient Compensation (7 June 1994)
- Information Notice 1994-41, Problems with General Electric Type CR124 Overload Relay Ambient Compensation (7 June 1994)
- Information Notice 1994-42, Cracking in the Lower Region of the Core Shroud in Boiling-Water Reactors (7 June 1994)
- Information Notice 1994-43, Determination of Primary-to-Secondary Steam Generator Leak Rate (10 June 1994, Topic: Grab sample)
- Information Notice 1994-44, Main Steam Isolation Valve Failure to Close on Demand Because of Inadequate Maintenance and Testing (16 June 1994)
- Information Notice 1994-44, Main Steam Isolation Valve Failure to Close on Demand because of Inadequate Maintenance and Testing (16 June 1994)
- Information Notice 1994-45, Potential Common-Mode Failure Mechanism for Large Vertical Pumps (17 June 1994, Topic: Biofouling)
- Information Notice 1994-46, Nonconservative Reactor Coolant System Leakage Calculation (20 June 1994)
... further results |
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