Information Notice 1996-65, Undetected Accumulation of Gas in Reactor Coolant System and Inaccurate Reactor Water Level Indication During Shutdown
December 11, 1996
NRC INFORMATION NOTICE 96-65: UNDETECTED ACCUMULATION OF GAS INREACTOR COOLANT SYSTEM AND INACCURATEREACTOR WATER LEVEL INDICATION DURINGSHUTDOWN
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 alertaddressees to ongoing issues related to an undetected loss of reactor coolant inventory atHaddam Neck caused by an accumulation of nitrogen in the reactor coolant system. It isexpected that recipients will review the information for applicability to their facilities andconsider actions, as appropriate, to avoid similar problems. However, suggestions containedin this information notice are not NRC requirements; therefore, no specific action or writtenresponse is required.BackgroundInformation Notice (IN) 94-36, "Undetected Accumulation of Gas in Reactor Coolant System,"issued on May 24, 1994, discussed an event at the Sequoyah Nuclear Power Plant inSeptember 1993 where gas accumulated in the reactor coolant system (RCS). The gasaccumulated because the temperature in the volume control tank was much lower thannormally expected. .(This lower temperature resulted from unusually low component coolingwater temperatures and from a maintenance problem with a cooling water valve that reducedthe heat sink temperature in the letdown heat exchanger.) The lower temperatures increasedthe solubility of gas in the volume control tank water so that there was more dissolved gas inthe water. When the water was transferred to the RCS by the charging system and heatedup in the reactor vessel, the gas came out of solution and collected in the RCS. Thisinformation notice also discussed a similar issue which occurred at the Salem NuclearGenerating Station on April 12, 1994.IN 96-37, "Inaccurate Reactor Water Level Indication and Inadvertent Draindown DuringShutdown," issued on June 18, 1996, discussed an event which occurred on September 13,1995, at Surry Unit 1. The plant was in cold shutdown and depressurized. Operators hadclosed the reactor head vent to install the reactor vessel cavity seal ring. After the seal ringwas in place, the reactor head vent was not reopened. This resulted in a loss of function ofthe only reactor vessel water level indication. As pressurizer relief tank nitrogen pressurewas gradually being reduced, an operator saw the standpipe indicated level increase as thePD~tEpb~c 9^r 9AmO}'1I4JI;~.OGO;L.x ' -11L>,Paydojlj eI W I1I .X- Lor-n K1-'IN 96-65December 11, 1996 gas bubble trapped in the reactor vessel head expanded, forcing water out of the reactor andup the surge line and standpipe. Unaware of the closed head vent and believing thestandpipe level indication, the operator increased letdown from the reactor coolant systemcold leg piping to maintain indicated level. This effectively reduced the inventory In the RCSby approximately 17.0 cubic meters [4500 gallons] over a period of 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.
Description of Circumstances
The reactor at Haddam Neck was in cold shutdown and decay heat was being removed bythe residual heat removal (RHR) system using the "A' RHR pump. The RCS wasdepressurized and a temporary primary vent header was connected to the reactor vesselhead. The volume control tank was being maintained at a pressure of 310 kPa [30 psig].rhe RCS loop stop valves had been closed to Isolate the reactor vessel from the steamgenerators. The Technical Specification required boration flow path was from the boric acidmetering tank, through the chemical and volume control system metering pump, and into theRCS. The reactor vessel level indication system (RVLIS) and core exit thermocouples weredisconnected in preparation for removal of the reactor vessel head. The operators wereusing pressurizer level indication and cavity level indication to monitor reactor vessel level(see Attachment 1).On August 28, 1996, the metering pump was to be declared inoperable because of anupcoming surveillance test on the emergency power supply for the pump, requiring thealignment of a different boric acid flow path. During the alignment, the operator opened bothvalve BA-V-354 (blended makeup to the volume control tank) and BA-V-355 (blendedmakeup to the charging pump suction). It appears that following this operation the operatormay have failed to fully seat one isolation valve (BA-V-355) between the top of the volumecontrol tank (nitrogen gas space) and the RCS (see Attachment 2). Note: the procedure inuse during the alignment did not allow valve BA-V-355 and BA-V-354 to be open at the sametime. This allowed nitrogen from the volume control tank to leak from the volume controltank, through several closed, leaking valves in the chemical and volume control system, andinto the reactor vessel. The installed vent system was unable to vent off nitrogen as fast asthe nitrogen was being added to the reactor vessel and a nitrogen bubble accumulated in thevessel head region. As the nitrogen gas displaced water from the reactor vessel Into thepressurizer, the water level in the reactor vessel decreased and the water level in thepressurizer increased.The pressurizer level instrumentation erroneously indicated that the reactor vessel was full ofwater. Pressurizer level slowly increased because of the displacement of water from thereactor vessel by nitrogen gas. The operators believed that the level increase was caused bywater leaking into the RCS through the loop stop valves. The operators tightened the valvesto stop the leakage. Water continued to be displaced from the reactor vessel by the growingnitrogen bubble. However, this was masked by the operators removing RCS inventory toremove the reactor vessel conoseals. For approximately four days, control room operatorswere unaware that nitrogen gas was leaking into the reactor vessel and causing the level inthe reactor vessel to decreas IN 96-65December 11, 1996 On September 1, 1996, the nitrogen gas supply to the volume control tank was isolated in anattempt to identify the source of the relatively high nitrogen usage. The isolation of thenitrogen gas stopped the nitrogen leakage into the RCS. The vent header system capacitynow exceeded the rate of gas intrusion and the vent began to release the nitrogen which hadaccumulated in the reactor vessel. The volume of nitrogen being removed from the reactorvessel was replaced by the water in the pressurizer. The pressurizer level rapidly decreaseduntil the level indication decreased off scale (low). Six additions of water to the RCS,totalling approximately 18.9 cubic meters (5000 gallons), were required to stabilizepressurizer level within the normal range.DiscussionThe event at Haddam Neck revealed a number of weaknesses. However, there are threeissues which the NRC has determined warrant particular notice. These issues are:(1) Inaccurate reactor vessel level instrumentation; (2) Inadequate reactor coolant inventorybalance; and (3) Non-condensible gas intrusion into the RCS. These issues are discussedbelow. An NRC augmented inspection team evaluated this event and reported its findings inNRC Inspection Report 50-213196-80.Inaccurate Reactor Vessel Level InstrumentationLack of accurate reactor vessel level instrumentation and lack of adequate inventorybalances while shutdown are issues of generic concem. The NRC has issued severalgeneric communications on the issue: these are listed in the "Related GenericCommunications" section. These generic communications discuss numerous events wheresafety-related equipment operability was challenged because of inaccurate levelinstrumentation.At Haddam Neck, the absence of direct reactor vessel monitoring instrumentation had anadverse affect on the operators' ability to monitor reactor vessel conditions. The availablelevel instruments (pressurizer level and cavity level) did not provide a direct indication ofreactor vessel level, The level instrumentation measured actual level in the pressurizer whichthe operators believed was representative of reactor vessel level because the pressurizer airspace was vented to the same vent header as the reactor vessel head (see Attachment 1).During this event, pressurizer level indication and cavity level indication -were notrepresentative of actual reactor vessel level because of a difference in pressure between thereactor vessel head and the pressurizer air space. The difference in pressure was caused bythe inability of the installed reactor vessel head vent system to remove nitrogen gas as fastas it was being introduced into the RCS.RVLIS, which does provide a direct reactor vessel level indication, was disconnected inpreparation for refueling maintenance activities. The core exit thermocouples are anotherdirect indication of reactor vessel conditions. The core exit thermocouples were alsodisconnected during the duration of this event.The RVLIS indicates reactor vessel level at discrete elevations. During this event, the RVLISwould have indicated abnormal reactor vessel level when the actual level dropped below the K>IN 96-65December 11, 1996 reactor vessel flange. Following this event, local RVLIS readings were collected and atemporary jumper was purchased and installed to provide RVLIS indications in the controlroom. A second jumper was installed to provide core exit thermocouple indication in thecontrol room.Inadequate Reactor Coolant Inventory BalanceThe licensee had not maintained an RCS inventory balance to account for the transfer ofwater into and out of the RCS. No detailed procedural guidance existed which required aninventory balance for draindown operations. The operators compensated for a lack ofdetailed procedural guidance by writing instructions in accordance with administrative controlprocedure 1.2-5.3, "Evaluation of ActivitiesXEvolutions Not Controlled by Procedure." Theinstructions written in accordance with administrative control procedure 1.2-5.3 do not requirethe same level of review and approval that other plant procedures receive. The guidancewritten for the RCS draindown did not require RCS inventory balances or specify referencelevels.On August 29, 1996, plant management made the decision to suspend refueling activitiesover the weekend. The operators were directed to and did refill the RCS. However, where5000 gallons had been removed from the RCS earlier, only 1000 gallons were added to theRCS to reach essentially the same indicated level. (The resulting 8-inch difference in P2,level indication between before and after only represented 500 gallons of the inventorydifference not the 4000 gallons which existed.)The magnitude of the apparent RCS inventory discrepancy was not explained to operationsmanagement nor did the operators solicit engineering and technical support to assist inresolving this discrepancy. The licensee had experienced leakage of the loop stop valvesduring past outages, however, an inventory balance may have alerted the operators to theactual magnitude of the inventory discrepancy, and may have caused the operators toquestion their initial conclusion that the increase in pressurizer level was caused by leakingstop valves.Non-Condensible Gas Intrusion into the RCSGas intrusion into the RCS and safety-related cooling system piping is an issue of genericconcem. The NRC has issued several generic communications on the issue: these arelisted in the "Related Generic Communications" section. These generic communicationsdiscuss numerous events where safety-related equipment was potentially renderedinoperable because of gas intrusion. The generic communications discuss the variousprocesses by which non-condensible gases have accumulated unknown to the reactoroperators in the RCS and safety-related cooling system piping. The event at Haddam Neckillustrates that gas intrusion events continue to occur in spite of the operational experienceavailable to the industry.At Haddam Neck, nitrogen intrusion into the RCS could potentially result in gas binding andcommon mode failure of the decay heat removal pumps and the charging pumps. In IN 96-65December 11, 1996 addition, nitrogen present in the RCS could potentially interfere with the ability of the steamgenerators to remove heat from the RCS via natural circulation cooling. The significance ofthe loss of the charging pumps at Haddam Neck is that a method of injecting water into thereactor vessel would be lost and that the charging pumps are needed to fill the RCS beforeopening the loop stop valves. The loop stop valves would need to be opened to allow theRCS to communicate with the steam generators, a condition necessary for the steamgenerators to remove heat from the RCS via natural circulation. In addition, the volume ofthe RCS increases significantly with the loop stop valves open, thus providing a largerpassive heat sink which would slow the heating of the RCS.At Haddam Neck the overpressure in the volume control tank was purposely maintained bythe licensee as an independent source of motive force to inject water into the RCS in theevent of a loss of other injection methods. The potential hazard of this condition is thatnitrogen may Intrude into the RCS if valves relied upon to isolate the volume control tankfrom the RCS either leak or are not properly controlled.During the event, the operators attempted to start the "B" RHR pump, however, it was foundto be seized. The licensee believes that the seizure occurred at the end of the lastsurveillance test and was not related to the gas intrusion event. The operators were unawarethat the "B" RHR had seized following its last operation on August 19, 1996. After the event,the licensee determined that the "B" RHR pump was inoperable throughout the event. Thefailure of the "B" RHR pump added to the significance of this event. If the "A" pump wasdamaged, the RHR system would not be available to remove decay heat. A mitigatingcondition at Haddam Neck is that two trains of the low pressure injection system wereavailable.The abnormal operating procedure for a loss of RHR requires that a cavitating RHR pump besecured and vented. However, the location of the RHR pump vents is not optimal andsignificant difficulty was encountered during venting the "B" RHR pump following maintenanceto address its seizure. Therefore, an effective venting of a RHR pump may not have beeneasy to achieve during an event if a pump had become gas bound.Related Generic CommunicationsInformation Notice 88-23, "Potential for Gas Binding of High-Pressure Safety Injection PumpsDuring a Loss-of-Coolant Accident," May 12, 1988.Information Notice 88-23, Supplement 1, "Potential for Gas Binding of High-Pressure SafetyInjection Pumps During a Loss-of-Coolant Accident," January 5, 1989.Information Notice 89-67, "Loss of Residual Heat Removal Caused by Accumulator NitrogenInjection," September 13, 1989.Information Notice 88-23, Supplement 2, "Potential for Gas Binding of High-Pressure SafetyInjection Pumps During a Loss-of-Coolant Accident," January 31, 199 K-/IN 96-65December 11, 1996 Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure SafetyInjection Pumps or Release of Reactor Coolant Outside Containment During a Loss-of-Coolant Accident," October 4, 1990.Information Notice 88-23, Supplement 3, "Potential for Gas Binding of High-Pressure SafetyInjection Pumps During a Loss-of-Coolant Accident," December 30, 1990.Information Notice 88-23, Supplement 4, "Potential for Gas Binding of High-Pressure SafetyInjection Pumps During a Loss-of-Coolant Accident," December 18, 1992.Information Notice 90-55, Recent Operating Experience on Loss of Reactor Coolant InventoryWhile in a Shutdown Condition," August 31, 1990.Information Notice 93-93, "Inadequate Control of Reactor Coolant System Conditions DuringShutdown," December 8, 1993.Information Notice 94-36, "Undetected Accumulation of Gas in Reactor Coolant System,"May 24, 1994.Information Notice 95-03, "Loss of Reactor Coolant Inventory and Potential Loss ofEmergency Mitigation Functions While in a Shutdown Condition,"January 18, 1995.Information Notice 96-37, "Inaccurate Reactor Water Level Indication and InadvertentDraindown During Shutdown," June 18, 1996.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of the technical contactslisted below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts: Eric J. Benner, NRR Warren C. Lyon, NRR(301) 415-1171 (301) 415-2947E-mail: ejb@nrc.gov E-mail: wcl@nrc.gov
Attachments:
1. The Undetected Nitrogen Gas Introductioninto the Reactor Vessel from the Charging Line2. Chemical and Volume Control System3. List of Recently Issued NRC Information Notices(1 l 4 [le} u IN 96-65KY t) December 11, 1996 Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure SafetyInjection Pumps or Release of Reactor Coolant Outside Containment During a Loss-of-Coolant Accident," October 4, 1990.Information Notice 88-23, Supplement 3, "Potential for Gas Binding of High-Pressure SafetyInjection Pumps During a Loss-of-Coolant Accident," December 30, 1990.Information Notice 88-23, Supplement 4, "Potential for Gas Binding of High-Pressure SafetyInjection Pumps During a Loss-of-Coolant Accident," December 18, 1992.Information Notice 90-55, Recent Operating Experience on Loss of Reactor Coolant InventoryWhile in a Shutdown Condition," August 31, 1990.Information Notice 93-93, "Inadequate Control of Reactor Coolant System Conditions DuringShutdown," December 8, 1993.Information Notice 94-36, "Undetected Accumulation of Gas in Reactor Coolant System,"May 24, 1994.Information Notice 95-03, "Loss of Reactor Coolant Inventory and Potential Loss ofEmergency Mitigation Functions While in a Shutdown Condition,"January 18, 1995.Information Notice 96-37, "Inaccurate Reactor Water Level Indication and InadvertentDraindown During Shutdown," June 18, 1996.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of the technical contactslisted below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.original signed by D. B. Matthews,4Yomas T. Martin, Director7 ~Division of Reactor Program ManagementI Office of Nuclear Reactor RegulationTechnical contacts: Eric J. Benner, NRR Warren C. Lyon, NRR(301) 415-1171 (301) 415-2947E-mail: ejbenrc.gov E-mail: wcl@nrc.govTech Editor has reviewed and concurred on 10/22/96
Attachments:
1. The Undetected Nitrogen Gas Introductioninto the Reactor Vessel from the Charging Line2. Chemical and Volume Control System3. List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:%EJBlHAD GAS.IN *SEE PREVIOUS CONCURRENC lOFC Contacts (A)BC/SRXB: BC/PECB:DRPM D/DNAME EBenner* TCollins* AChaffee* TMa\/nl_ _ WLyon*DATE 10/30/96 11/05/96 11/25/96 E ,1,9610/30/96OFFICIAL RECO)RD COPY IN 96-XX.) November X, 1996 Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure SafetyInjection Pumps or Release of Reactor Coolant Outside Containment During a Loss-of-Coolant Accident," October 4, 1990.Information Notice 88-23, Supplement 3, "Potential for Gas Binding of High-Pressure fetyInjection Pumps During a Loss-of-Coolant Accident," December 30, 1990.Information Notice 88-23, Supplement 4, "Potential for Gas Binding of High-P rsure SafetyInjection Pumps During a Loss-of-Coolant Accident," December 18, 1992.Information Notice 90-55, Recent Operating Experience on Loss of Rea or Coolant InventoryWhile in a Shutdown Condition," August 31, 1990.Information Notice 93-93, "Inadequate Control of Reactor Coolan ystem Conditions DuringShutdown," December 8, 1993.Information Notice 94-36, "Undetected Accumulation of Gabin Reactor Coolant System,"May 24, 1994.Information Notice 95-03, "Loss of Reactor Coolant I entory and Potential Loss ofEmergency Mitigation Functions While in a Shutdo n Condition,"January 18, 1995.Information Notice 96-37, "Inaccurate Reacto ater Level Indication and InadvertentDraindown During Shutdown," June 18, 19This information notice requires no spe ic action or written response. If you have anyquestions about the information in this otice, please contact one of the technical contactslisted below or the appropriate Offi of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts: Eric .Benner, NRR Warren C. Lyon, NRR(30 415-1171 (301) 415-2947E- ail: ejbenrc.gov E-mail: wclInrc.gov
Attachments:
1. The Undetecte Nitrogen Gas Introductioninto the Rea or Vessel from the Charging Line2. Chemical a Volume Control System3. List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:XEJB1%HADGAS.lN *SEE PREVIOUS CONCURRENCEOFC Contacts (A)BC/SRXB: BC/PECB:DRPM D/DNAME EBenner* TCollins* AChaffee* TMaW \WLyon*_DATE 10/30/96 11/05/96 11/25/96 11f9610/30/96OFFICIAL RECORD COPY IN c -KXNo~ber X, 1996 Information Notice 90-64, "Potential for Common-Mode Failure of High Pressure tyInjection Pumps or Release of Reactor Coolant Outside Containment During a ss-of-Coolant Accident," October 4, 1990.Information Notice 88-23, Supplement 3, "Potential for Gas Binding of gh-Pressure SafetyInjection Pumps During a Loss-of-Coolant Accident," December 30, 90.Information Notice 88-23, Supplement 4, "Potential for Gas Bing of High-Pressure SafetyInjection Pumps During a Loss-of-Coolant Accident," Decem r 18,1992.Information Notice 90-55, Recent Operating Expenien n Loss of Reactor Coolant InventoryWhile in a Shutdown Condition," August 31, 1990.Information Notice 93-93, "Inadequate Control o eactor Coolant System Conditions DuringShutdown," December 8, 1993.Information Notice 94-36, "Undetected A umulation of Gas in Reactor Coolant System,"May 24, 1994.Information Notice 95-03, "Loss of eactor Coolant Inventory and Potential Loss ofEmergency Mitigation Functions ile in a Shutdown Condition,"January 18, 1995.Information Notice 96-37, "I ccurate Reactor Water Level Indication and InadvertentDraindown During Shutdo n," June 18, 1996.This information notirequires no specific action or written response. If you have anyquestions about the formation in this notice, please contact one of the technical contactslisted below or the ppropriate Office of Nuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechni contacts: Eric J. Benner, NRR Warren C. Lyon, NRR(301) 415-1171 (301) 415-2947E-mail: ejb@nrc.gov E-mail: wcl@nrc.govAft chments:1. The Undetected Nitrogen Gas Introduction into the Reactor Vessel from theCharging Line2. Chemical and Volume Control System3. List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:\EJBlHAD GAS.IN *SEE PREVIOUS CONCURRENCEOFC Contacts (A)BC/SRXB: BCIPECB:DRPM DIDRPMNAM EBenner* TCollins* AChaffee A TMartinE WLyon* ___ _DATE 10/30/96 1 5p 11/05/96 ii 66i6 /9610/30/96OFFICIAL RECORD COPY IN 96-XXNovember X. 1996 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectDivision of Reactor Pr ram ManagementOffice of Nuclear Re tor RegulationTechnical contacts: Eric J. Benner. NRR(301) 415-1171E-mail: ejb@nrc.govWarren C. Lyon. NRR(301) 415-2947E-mail: wcl@nrc.gov
Attachments:
1. The Undetected Nitrogen Gas Introdution into the Reactor Vessel from theCharging Line2. Chemical and Volume Control Syst3. List of Recently Issued NRC Inf rmation NoticesN NA)M P -XCC \ -XX, rDOCUMENT NAME:ARA. *SEE PREVIOUS CONCURRCEOFC Co qacts (A)BC/SRXB: BC/PECB:DRPM D/DRPMNAME enner* TCollins* AChaffee TMartinLyon*DATE 10/30/96 11/05/96 / /96 / /9610/30/96OFFICIAL RE CORD COPY I ' XI<KIN 96-61November 7. 1996 Information Notice 90-55, Recent Operating Experience on Loss of ReactorCoolant Inventory While in a Shutdown Condition," August 31, 1990.Information Notice 93-93, "Inadequate Control of Reactor Coolant SystemConditions During Shutdown." December 8, 1993.Information Notice 94-36. "Undetected Accumulation of Gas in Reactor CoolantSystem." May 24, 1994.Information Notice 95-03. "Loss of Reactor Coolant Inventory and PotentialLoss of Emergency Mitigation Functions While in a Shutdown Condition."January 18. 1995.Information Notice 96-37. "Inaccurate Reactor Water Level Indication andInadvertent Draindown During Shutdown." June 18. 1996.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Eric J. Benner, NRR(301) 415-1171E-mail: ejb@nrc.govWarren C. Lyon, NRR(301) 415-2947E-mail: wcl@nrc.gov
Attachments:
1. Figure 1: Chemical and Volume Control System2. List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:\EJB1\HAD GAS.IN *SEE PREVIOUS CONCURRENCEOFC Contacts (A)BC/SRXB: BC/PECB:DRPM D/DRPMNAME EBenner* TCollins* AChaffee >- TMartinWLyon*_ _ _DATE 10/30/96 11/05/96 It / 1/96 / /9610/30/96OFFICIAL RECORD COPY
-IN 96-61November 7. 996Information Notice 90-55, Recent Operating Experience onCoolant Inventory While in a Shutdown Condition," AugustLoss of Reactor31. 1990.Information Notice 93-93, "Inadequate Control of Reactor Coolant SystemConditions During Shutdown," December 8. 1993.Information Notice 94-36. "Undetected Accumulation of Gas in Reactor CoolantSystem," May 24. 1994.Information Notice 95-03, "Loss of Reactor Coolant Inventory and PotentialLoss of Emergency Mitigation Functions While in a Shutdown Condition,"January 18. 1995.Information Notice 96-37, "Inaccurate Reactor Water Level Indication andInadvertent Draindown During Shutdown." June 18. 1996.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Eric J. Benner, NRR(301) 415-1171E-mail: ejb@nrc.govWarren C. Lyon. NRR(301) 415-2947E-mail: wcl@nrc.gov
Attachments:
1. Figure 1: Chemical and2. List of Recently IssuedVolume Control SystemNRC Information NoticesDOCUMENT NAME: G:\EJB1\HAD GAS.IN *SEE PREVIOUS CONCURRENCEOFC Contacts (A)BC/SRXB: BC/PECB:DRPM D/DRPMNAME EBenner* TCollins* AChaffee TMartinWLyon* V-,DATE 10/30/96 11/05/96 Il/(a/96 / /9610/30/96 lOFFICIAL RECORD COPY INVi-xxNovember XX, 996Information Notice 90-55, Recent Operating Experience onCoolant Inventory While in a Shutdown Condition," AugustInformation Notice 93-93, "Inadequate Control of ReactorConditions During Shutdown," December 8, 1993.Loss of Reactor31, 1990.Coolant SystemInformation Notice 94-36, "Undetected Accumulation of Gas in Reactor CoolantSystem," May 24, 1994.Information Notice 95-03, "Loss of Reactor Coolant Inventory and PotentialLoss of Emergency Mitigation Functions While in a Shutdown Condition,"January 18, 1995.Information Notice 96-37, "Inaccurate Reactor Water Level Indication andInadvertent Draindown During Shutdown," June 18, 1996.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contact(s):Eric J. Benner, NRR(301) 415-1171E-mail: ejb@nrc.govWarren C. Lyon, NRR(301) 415-2947E-mail: wcl@nrc.gov
Attachments:
1. Figure 1: Chemical and Volume Control System2. List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:\EJB1\HADGAS.IN*SEE PREVIOUS CONCURRENCEOFC Contacts (A)BC/SRXB: BC/PECB:DRPM D/DRPMNAME EBenner* TCollins* AChaffee TMartinWLyon*DATE 10/30/96 11/05/96 / /96 / /9610/30/96OFFICIAL RECORD COPY IN 94-36, Supp. 1November XX, 1996 Information Notice 88-23, Supplement 1. "Potential for Gas Binding of High-Pressure Safety Injection Pumps During a Loss-of-Coolant Accident,"January 5. 1989.Information Notice 89-67. "Loss ofNitrogen Injection." September 13,Information Notice 88-23, SupplemerPressure Safety Injection Pumps DutJanuary 31, 1990.Residual Heat Removal Caused by Accumulator1989.it 2, "Potential for Gas Binding of High-,ing a Loss-of-Coolant Accident,"Information Notice 90-64, "Potential for Common-Mode Failure of High PressureSafety Injection Pumps or Release of Reactor Coolant Outside ContainmentDuring a Loss-of-Coolant Accident," October 4, 1990.Information Notice 88-23.Pressure Safety InjectionDecember 30. 1990.Information Notice 88-23.Pressure Safety InjectionDecember 18, 1992.Supplement 3. "Potential for Gas Binding of High-Pumps During a Loss-of-Coolant Accident,"Supplement 4. "Potential for Gas Binding of High-Pumps During a Loss-of-Coolant Accident,"Information Notice 93-93, "Inadequate Control of Reactor Coolant SystemConditions During Shutdown," December 8. 1993.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice. please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contact(s):Eric J. Benner, NRR(301) 415-1171E-mail: ejb@nrc.govWarren C. Lyon, NRR(301) 415-2947E-mail: wcl@nrc.gov
Attachments:
1. Figure 1: Chemical and Volume Control System2. List of Recently Issued NRC Information NoticesDUCUMLNI NAML: b:\LJBi\MAV UAb.1N -Ztt FKtVIUUZ LUiNUKKMULOFC Contacts (A)BC/SRXB: BC/PECB:DRPM D/DRPMNAME EBenner* TCollins* AChaffee TMartinWLyon*DATE 10/30/96 11/05/96 / /96 , / /96110/30/96 a-[OFFICIAL RECORD COPY IN 94-36. Supp. 1November XX, 1996 Information Notice 89-67, "Loss of Residual Heat Removal CausedNitrogen Injection," issued September 13. 1989.Information Notice 88-23, Supplement 2, "Potential for GasPressure Safety Injection Pumps During a Loss-of-CoolantJanuary 31, 1990.i deiby Accumulator'7ing of High-it," issuedInformation Notice 90-64. "Potential for Common-Mod Tailure of High PressuSafety Injection Pumps or Release of Reactor Coolayt Outside ContainmentDuring a Loss-of-Coolant Accident." issued Octob 4. 1990.Information Notice 88-23. Supplement 3. "Pote ial for Gas Binding of High-Pressure Safety Injection Pumps During a Lo -of-Coolant Accident," issuedreDecember 30. 1990.Information Notice 88-23,Pressure Safety InjectionDecember 18, 1992.SupplementPumps Durii/"Potential for Gas Binding of High-a Loss-of-Coolant Accident," issuedInformation Notice 93-93. "Inade 4ate Control of Reactor Coolant SystemConditions During Shutdown," i ued December 8. 1993.This information notice req res no specific action or written response. Ifyou have any questions abo the information in this notice, please contactone of the technical con cts listed below or the appropriate Office ofNuclear Reactor Regulaton (NRR) project manager.Thomas T. Martin, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical): Eric J. Benner, NRR(301) 415-1171Internet: ejbl@nrc.govWarren C. Lyon, NRR(301) 415-2947Internet: wcl@nrc.govTech ditorAt chment:reviewed and concurred on October 18, 1996.List of Recently Issued NRC Information NoticesContacts BC/SRXB:DSSA T0 BC/PECB:DRPM D/DRPMNAME EBennerrtr6 4X AChaffee TMartinWLyon /0/lX, 'z: zgt,_4llDATE On) I 6"I /'I/ /96 / /96____ 17t /l%9 / f9[OFIIA ECOR COY]DOCUMENT NAME: G:\EJB1\HAD GAS.IN THE UNDETECTED NITROGEN GAS INTRODUCTION INTOTHE REACTOR VESSEL FROM THE CHARGING LINESteam Vent HeadergeneratorPressuriier Pressurizer (Vent TemporaryHoseri r- ~691' EL HaPressurizer VentAir (gg Level-Head Full 355" EL-12%Water .301- EL 351 EL Top of He(d.!: Cavty /_ 1° _\\ReactorVaevve,: 2330 EL Indicatore .Ntogn. 1 9Fae 270" EL>(^i\ HotLeg Gas aDbl o; l lrreLOOb1°P Wate LinReacor Cold LegCl 10" Pressurizer 10" RHRCoolant Surge (Lin Suction Line IPup(Loop 4) (Loop 1) a CY%Loop #4 EL1R9(- IEl. 185" -j 27112"EL 172" -/Reactor Hoke lo1j aU t a inftOReactorl i n t O f t D l ? * -
CHEMICAL & VOLUME CONTROL SYSTEMNITROGEN GAS LEAK PATH FROM VOLUMECONTROL TANK TO THE RCSTo RCSLoop #2Cold LegVolume ControlTank(Valve Closed -Leaking ByBordeAcidBlendercOi CD =COC)(D CD O C3 cn c-or I1:CD CM =o i en C_& --rtoDn KJAttachment 3IN 96-65December 11, 1996 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to96-6496-6396-6296-6196-6096-59Modifications to Con-tainment Blowout PanelsWithout AppropriateDesign ControlsPotential Safety IssueRegarding the Shipmentof Fissile MaterialPotential Failure of theInstantaneous Trip Functionof General Electric RMS-9ProgrammersFailure of a Main Steam SafetyValve to Reseat Caused by anImproperly Installed ReleaseNutPotential Common-Mode Post-Accident Failure of ResidualHeat Removal Heat ExchangersPotential Degradation ofPost Loss-of-CoolantRecirculation Capabilityas a Result of DebrisRCP Seal Replacement withPump on Backseat12/10/9612/05/9611/20/9611/20/9611/14/9610/30/9610/30/96All holders of OLsor CPs for nuclearreactorsAll U.S. NuclearRegulatory Commissionlicensees authorizedto possess specialnuclear material inunsealed quantitiesgreater than a criticalmassAll holders of OLsand CPs for nuclearpower plantsAll holders of OLs orCPs for nuclear powerreactorsAll holders of OLs orCPs for nuclear powerreactorsAll holders of OLs orCPs for nuclear powerreactorsAll holders of OLs orCPs for pressurized-waterreactors96-58OL = Operating LicenseCP = Construction Permit