Information Notice 1988-61, Control Room Habitability - Recent Reviews of Operating Experience

Control Room Habitability - Recent Reviews of Operating Experience

ML031150218
Person / Time
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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	08/11/1988
From:	Rossi C E Office of Nuclear Reactor Regulation
To:
References
IN-88-061, NUDOCS 8808050248
Download: ML031150218 (12)

UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555August 11, 1988NRC INFORMATION NOTICE NO. 88-61: CONTROL ROOM HABITABILITY -RECENT REVIEWSOF OPERATING EXPERIENCE

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.

Purpose

This information notice is being provided to alert addressees to potentialproblems resulting from design or analysis deficiencies identified in controlroom ventilation systems. It is expected that recipients will review theinformation for applicability to their facilities and consider actions, asappropriate, to avoid similar problems. However, suggestions contained inthis information notice do not constitute NRC requirements; therefore, nospecific action or written response is required.

Description of Circumstances

The NRC has received several construction deficiency and licensee eventreports pertaining to safety systems that are used to ensure control roomhabitability. These reports identified potential safety concerns resultingfrom design deficiencies, which were attributed to inadequate analysis andan inability to justify those conditions that were assumed in previous evalu-ations of plant design and operation. These reports are summarized below.Comanche Peak 1 and 2:On January 15, 1988, the permit holder determined that radiation doses tocontrol room operators for some postulated radiological accidents couldexceed the limits of General Design Criterion 19 of Appendix A to 10 CFR 50.This determination was attributed to an inadequate analysis of control roomhabitability systems for postulated radiological accidents. Particular ac-cident scenarios that were incompletely analyzed included a fuel handlingaccident and a rupture of a radioactive gaseous waste tank. To correctthis situation, the licensee is developing new calculations, upgrading theexisting control room intake radiation monitors and associated cables tosafety-related Class 1E requirements, and installing two additional safety-related Class 1E radiation monitors, one in each control room intake.88850248 '

IN 88-61August 11, 1988 Quad Cities:on November 25, 1987, the licensee's engineering department discovered thatdesign basis assumptions used in the control room habitability study wereinconsistent with technical specification requirements. The study was con-ducted to satisfy a requirement of the NRC's TMI Action Plan. The adsorptionefficiencies of the standby gas treatment system and control room HYAC systemwere assumed at 99 percent for organic iodide removal. The relevant technicalspecifications, however, require only an organic iodide removal efficiency morethan or equal to 90 percent. All the filters meet the technical specificationrequirements. Since December 31, 1984, tests of filter efficiencies indicatethat the relevant assumptions of the study were met with two exceptions. Thelicensee attributes the cause for this condition to be an inadequate review ofdesign and analysis during the development of the study.Vogtle 1 and 2:On July 2, 1987, plant engineering personnel identified an inadequacy in thedose analysis for control room operators. On receipt of a safety injectionsignal or a control room outside air intake high radiation signal, the controlroom heating, ventilating, and air conditioning (HVAC) system is automaticallytransferred from the normal system units to the essential control room (ECR)fan-filter units in the emergency mode of operation. The ECR system consistsof two redundant and physically separated 100 percent capacity fan-filter unitsfor each side of the control room, associated with the corresponding reactorunit (four for the combined Unit 1 and Unit 2 control room (Figure 1)). Eachof the ECR units belongs to a different safety train, but portions of the out-side air intake ductwork and control room supply and return ductwork are commonto each of the units. On initiation of the ECR system, the associated motor-operated dampers for the essential units are automatically opened and thosefor the normal units are automatically closed.When both of the ECR fan-filter units are operating, loss of power to one ofthese units can reduce the amount of outside air available to pressurize thecontrol room. This can happen because the dampers losing power fail in the"as-is" position. At the time of the identification of the problem, no back-draft dampers were installed. This degrades the ECR HVAC system by establishingflowpaths through the common ductwork and the ductwork of the failed unit backto the suction of the operating unit, which could potentially reduce the outsideair flow to the control room and reduce the control room pressure below thedesign value. Maintenance of the design control room pressure is required tominimize unfiltered inleakage.The licensee concluded that the actual effect on control room pressure couldnot be calculated in the absence of test data and decided to modify the systemby installing backdraft dampers, as noted on Figure 1, for the ECR HVAC systemsof both Units 1 and IN 88-61August 11, 1988 On July 4, 1987, an additional condition was discovered that could have causedan insufficient control room pressure. All ECR systems share common outsideair supply ductwork. The common air supply ductwork has intakes from the out-side atmosphere associated with both Units 1 and 2. Redundant isolation dampersin series are provided for both Unit 1 and Unit 2 duct openings from the outsideatmosphere. During construction, the Unit 2 duct opening had been isolated bylocking the dampers closed. If one of the outside air isolation dampers forUnit 1 had closed as the assumed single failure of an active component, nosource of outside air would be available to the control room (shared by bothUnits) and the required pressure would not be maintained. Because the licenseehad removed chlorine gas sources from the site, the capability to isolate toxicgases was no longer needed. Thus, the licensee deactivated and tagged open theoutside air isolation dampers.For all these problems, the licensee concluded that the defective conditionswould have been discovered earlier with an adequate failure modes and effectsanalysis.Beaver Valley 2:On March 27, 1987, the permit holder determined that timers initiated by con-tainment isolation phase B signals were not served with uninterruptible poweras required. These timers are designed to actuate banks of compressed air tosupply the control room emergency pressurization system one hour after receiptof the isolation signal. They were powered from the respective fan controlcircuit energized by an emergency ac distribution panel fed from an emergencymotor control center. Loss of offsite power would interrupt power to the motorcontrol center. If a loss of power occurred after timer initiation, the timerswould reset to the beginning of the timing cycle and would not begin the cycleuntil power was restored to the emergency motor control center. The compressedair would thus not be supplied after one hour. To enhance the reliability ofthe safety systems, the licensee revised the circuitry to power the timers fromthe Class lE 125-V dc battery system.McGuire 1:On November 5, 1987, the licensee discovered during an 18-month surveillancetest of the control area ventilation and chilled water system that control roompressure was below the technical specification requirement. The licensee de-termined that the cause was leaking seals on seven control room doors. Thedoors were designed to seal by seating against sealing strips in the doorframes. Although not visibly deteriorated, the sealing material apparentlyhad been deformed and compressed over time from normal use of the doors. Thelicensee adjusted manual volume dampers to increase total train air flow andthe proportion of outside air flow to the maximum 60 percent allowed in the IIN 88-61August 11, 1988 test procedure. This action was effective in increasing control room pressureto meet the technical specification requirement. The licensee installed sealingtape around the seven doors and established a preventive maintenance program toinspect the seals on all control room doors every 6 months for a 1-year period.The licensee plans to determine an appropriate frequency for preventive mainte-nance of the door seals. The surveillance test of the control area ventilationand chilled water system will also be repeated every 6 months until sufficientinformation is obtained for determining an appropriate frequency.Farley 1:On June 5, 1987, the licensee discovered that none of four fire dampers in thecontrol room ventilation system would fully close and latch with or without airflow because they had not been exercised and/or lubricated or, in one case, be-cause a latch was damaged. In addition, investigation revealed that the damperswould not have received an actuation signal from a Firestat set to sense 1600Fin the control room ceiling because of installation errors. The licensee at-tributed the problems to three causes: a design deficiency pertaining to thefull closure and latching of the dampers, inadequate testing of the actuationcircuitry, and inadequate preventive maintenance of the dampers.Discussion:In addition to the above, the NRC has recently completed an engineering evalu-ation, "Design and Operating Deficiencies in Control Room Emergency VentilationSystems," AEOD/E802, April 1988 based on recent events that highlight singlefailure vulnerabilities in control room emergency ventilation systems.* TheNRC also has recently conducted a survey of control room habitability systemsat 12 operating plants. Numerous discrepancies were found between the analyzedand actual performance of these systems. For example, differences exist betweendesign, construction, operation, and/or testing of these systems and the de-scriptions and analyses provided in licensing documents, as for example in theassumptions used in the toxic gas and radiation dose calculations. In addition,analyses assumptions have not always been consistent with technical specifi-cation requirements. The NRC has issued several information notices relatedto this subject (see Attachment '2). Resolution of Generic Issue 83: ControlRoom Habitability is also ongoing.*A copy of the report is available in the NRC Public Document Room, 1717 hStreet, N.W., Washington, D.C. 20555, for inspection and copyin IN 88-61August 11, 1988 No specific action or written response is required by this information notice.If you have any questions about this matter, please contact one of the techni-cal contacts listed below or the Regional Administrator of the appropriateregional office.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts: Vern Hodge, NRR(301) 492-1169Charles R. Nichols, NRR(301) 492-0854

Attachments:

1. Figure 1. Schematic Air Flow Path Diagram of Essential Control RoomHeating, Ventilating, and Air Conditioning System (ECP HVAC) at Vogtle.Assumed Containment Isolation Signal for Unit 1 with Train B Failed.2. List of Information Notices Related to Control Room Habitability Systems3. List of Recently Issued NRC Information Notices I OUTSIDEL , AIROUTSIDE;AIR% v vvOUTSIDE AIR SUPPLY DUCT((cn cLA CO 0~FIGURE 1. SCHEMATIC AIR FLOW PATH DIAGRAM OF ESSENTIAL CONTROL ROOM HEATING, VENTILATING, AND AIR > o =CONDITIONING SYSTEM (ECR HVAC) AT VOGTLE. ASSUMED CONTAINMENT ISOLATION SIGNAL FOR -CUNIT 1 WITH TRAIN B FAILED.0C03 Attachment 2IN 88-61August 11, 1988 LIST OF INFORMATION NOTICESRELATED TO CONTROL ROOM HABITABILITY SYSTEMSNO.86-7685-8983-62TITLEDATEProblems Noted in Control RoomEmergency Ventilation SystemsPotential Loss of Solid-StateInstrumentation Following Failureof Control Room CoolingFailure of Redundant and Toxic GasDetectors Positioned at Control RoomVentilation Air IntakesAugust 28, 1986November 19, 1985September 26, 1983

'- .dachment 3IN 88-61August 11. 4988Page I of ILIST OF RECENtLY ISSUEDNRC INFORMIATION NOTICESInfTornationNotice No. Subject88-60 Inadeouste Design andInstallation of WatertightPenetration SealsB8-04. Inadecuate QualifitationSupplerent I and Documentation of FireBarrier Penetration Seals88-59 Kain Steam Isolation ValveGuide Rail Failure atWaterford Unit 388-5888-5788-5688-55B8-5488-S-Potential Probiems withASEA Brown Boveri TE-S1LTime-COercurrent PelaysPotential Loss of SafeShutccwn Eoulprent Due toPremature Siliccr ControlleeRectifier FailurePotential Prcblems wtthSiliccre Foam Fire BarrierPenetration SealsPotential Problems Causedby Sirgle Failure of anEngineered Safety FeatureSwing BusFajiure of Circuit BreakerFollowing Installation ofAmptector Direct TripAttactrentLicensee Violations of NRCReculations. Whicn Leo toleoical DiagnosticmisaoministrationsDate ofIssuanceS/11B88/9/88819/888/8/E88/8/888/4/888/3/187/28/687/28esIssued toAll holders of OLsor CPs for nuclearpower reactors.All holders of MLsor CPs for nuclearpower reactors.All holders of OLsor CFs for nuclearpower reactors.All holders of OLsor CPs 'or nuclearpower oeactors.All holders of QLsor CFs for nuclearpower reactors.All holders of OLsor CFs 'or nuclearpower reactors.All holders of CIsor CPs for nuclearpower reactors.All holders of OLsor CPs for nuclearpower reactors.All manufacturers anddistributcrs of radio-ptarraceuticals forhuran use. nucledrpharracies. anonecical licensees.-TOL

• Doeratino LicenseCP

• Ccnstructicr. PermitUNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D.C. 20555OFFICIAL BUSINESSPENALTY FOR PRIVATE USE. $300FIRST CLASS MAILPOSTAGE & FEES PAIDUSNACP£RMIT Ne. S67 IN 88-61August 11, 1988 No specific action or written response is required by this information notice.If you have any questions about this matter, please contact one of the techni-cal contacts listed below or the Regional Administrator of the appropriateregional office.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts:Vern Hodge, NRR(301) 492-1169Charles R. Nichols, NRR(301) 492-0854

Attachments:

1. Figure 1. Schematic Air Flow Path Diagram of Essential Control RoomHeating, Ventilating, and Air Conditioning System (ECR HVAC) at Vogtle.Assumed Containment Isolation Signal for Unit 1 with Train B Failed.2. List of Information Notices Related to Control Room Habitability Systems3. List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCES08/G /88NRR *A C SPLB:DEST:NRRJWCraig05/06/88*C/OGCB:DOEA:NRRCHBerlinger05/31/88*SAD/DEST:NRRAThadani05/13/88*PPMB:ARMTechEd04/05/88*D/DEST:NRRLCShao05/16/88*OGCB:DOEA:NRRCVHodge03/31/88*SPLB:DEST:CRNichols03/31/88 IN 88-XXMay xx, 1988 habitability systems at 12 operating plants. Numerous types of discrepanciesare described involving differences between (1) the design, construction,operation and/or testing of these systems and (2) corresponding technicalspecifications when compared with the descriptions and analyses provided inlicensing basis documents, Including assumptions in the toxic gas and radiationdose calculations.No specific action or written response is required by this information notice.If you have any questions about this matter, please contact the technicalcontacts listed below or the Regional Administrator of the appropriate regionaloffice.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts:Vern Hodge, NRR(301) 492-1169Charles R. Nichols, NRR(301) 492-0854

Attachments:

1. Summaries of Recent Reports Concerning Control Room Habitability2. Figure 1. Schematic Flow Path Diagram of Essential Control Room Heating,Ventilating, and Air Conditioning System at Vogtle 1 and 23. List of References4. List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCES*OGCB:DOEA:NRRCVHodge03/31/88*SPLB:DEST:NRRCRNichols03/31/88D/DOEA:NRRCERoss i05/ /88*A/C/SPLB:DEST:NRRJWCrai g05/06/88C¢6C/OGCB:DOEA:NRRCHBerl ingerO/n-/88SAD/DEST:NyJSpAThadani Al05/y88*PPMB:ARMTechEd04/05/88D/DEST:N/ILCShao05//88A IN 88-XXMay xx, 1988 control room habitability systems at 12 operating plants. Numerous types ofdiscrepancies are described between the design, construction, operation andtesting of these systems and corresponding technical specifications comparedwith the descriptions and analyses provided in licensing basis documents,including assumptions in the toxic gas and radiation dose calculations. TheNRC plans to distribute the report to all holders of operating licenses orconstruction permits for nuclear power reactors.No specific action or written response is required by this information notice.If you have any questions about this matter, please contact the technicalcontacts listed below or the Regional Administrator of the appropriate regionaloffice.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts:Vern Hodge, NRR(301) 492-1169Charles R. Nichols, NRR(301) 492-0854

Attachments:

1. Summaries of Recent Reports Concerning Control Room Habitability2. Figure 1. Schematic Flow Path Diagram of Essential Control Room Heating,Ventilating, and Air Conditioning System at Vogtle 1 and 23. List of References4. List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCES*OGCB:DOEA:NRRCVHodge03/31/88D/DOEA:NRRCERoss i5/ /88*SPLB:DEST:NRR , /8PLB:DEST:NRRCRNichols {Craig03/31/88C/OGCB:DOEA:NRRCHBerlinger05/ /88SAD/DEST:NRRAThadani05/ /88*PPMB:ARMTechEd04/05/88D/DEST:NRRLCShao05/ /88 IN 88-XXMarch xx, 1988 No specific action or written response is required by this information notice.If you have any questions about this matter, please contact the technicalcontact below or the Regional Administrator of the appropriate regional office.Charles E. Rossi, DirectorDivision of Operational Events AssessmentOffice of Nuclear Reactor RegulationTechnical Contacts:Vern Hodge(301) 492-1169Charles R. Nichols, NRR(301) 492-0854

Attachments:

1. Summaries of Recent Events Concerning Control Room Habitability2. Figure 1. Schematic Flow Diagram of Control Room Essential Heating,Ventilating and Air Conditioning System at Vogtle 1 and 23. List of References4. List of Recently Issued NRC Information NoticesOGCB:DOEA:NRRCVHodge03/31/88D/DOEA:NRRCERossi03/ /88A/C/SPLB:DEST:NRRJWCraig03/ /88C/OGCB:DOEA:NRRCHBerlinger03/ /88SAD/DEST:NRRAThadani03/ /88SPLB:DEST:NRRCRNichols034X /88PPMB:ARMTechEd03/ /88D/DEST:NRRLCShao03/ /88