Information Notice 1986-30, Design Limitations of Gaseous Effluent Monitoring Systems

Design Limitations of Gaseous Effluent Monitoring Systems

ML031220651
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, 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, Skagit, Marble Hill
Issue date:	04/29/1986
From:	Jordan E L NRC/IE
To:
References
IN-86-030, NUDOCS 8604280122
Download: ML031220651 (4)

SSINS No.: 6835IN 86-30UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF INSPECTION AND ENFORCEMENTWASHINGTON, D.C. 20555April 29, 1986IE INFORMATION NOTICE NO. 86-30: DESIGN LIMITATIONS OF GASEOUS EFFLUENTMONITORING SYSTEMS

Addressees

All nuclear power reactor facilities holding an operating license or a con-struction permit.

Purpose

This notice is provided to alert licensees to two design limitations noted inthe use of Eberline's SPING-4 (system particulate iodine and noble gas) gaseouseffluent monitoring systems. The first deals with the limitations of thedetection capability of the SPING-4 monitoring system. Some licensees areincorrectly relying on the SPING-4 to meet all of the post-accident require-ments of NUREG-0737. The second deals with noble gas adsorption that couldinterfere with routine operational low-level monitoring.It is expected that recipients will review this information for applicabilityto their facilities and consider actions, if appropriate, to preclude problemsrelated to these limitations at their facilities. However, suggestions con-tained in this notice do not constitute NRC requirements; therefore, no specif-ic action or written response is required.

Description of Circumstances

The Eberline SPING-4 is designed to monitor radioactive noble gasses, particu-lates and iodines in plant gaseous effluents. By using three overlappingchannels, the noble gas (NG) monitor has a detection capability of 10-7 to 105pCi/cc (Xe-133 equivalent). The low-range channel employs a beta scintillationdetector. The mid- and high-range channels of the NG monitor use energy-compensated GM tube detectors.Conformance to NUREG-0737 II.F.1:Item II.F.1.1 of NUREG-0737, "Clarification of TMI Action Plan Requirements,"issued November 1980, requires licensees to have the capability to detect andmeasure concentrations of NG fission products in plant effluents (up tolo5 pCi/cc for undiluted containment exhaust) during and following an accident.Recent NRC regional inspections of NUREG-0737 implementation indicate that8604280122 IN 86-30April 29, 1986 some licensees have installed SPING-4 monitors and mistakenly consider themadequate to meet all of the requirements of Item II.F.1.1. Although theSPING-4 does have an upper detection capability of 105 pCi/cc, its associatedmicrocomputer is vulnerable to radiation damage from a total integrated dosegreater than 1000 rads. Therefore, it is unlikely the SPING-4 would survivethe course of an accident. Eberline has indicated that the SPING-4 wasdesigned primarily as a normal-range monitor with extended capabilities forbrief excursions to concentrations greater than 102 pCi/cc. Full-range moni-toring consistent with Item II.F.1.1 can be achieved by using the SPING-4 inconjunction with an accident monitor (with a remote microprocessor) such asEberline's model AXM-1. The accident monitor comes on line when excessivelyhigh activity levels are sensed while the SPING-4 isolates itself and goes intoa purge cycle.Noble Gas Adsorption:Eberline has noted noble gas adsorption with the plastic scintillator whileperforming a SPING-4 calibration. This calibration compared the SPING-4 outputwith a GeLi detection system output, as the concentration of a reference gas(Xe-127) was decreased. The concentration of Xe-127 (initially at 210 pCi/cc)in the closed test loop was decreased by vent and dilution operations. Cali-bration was interrupted after 2 days to correct problems with the GeLi system.The system was allowed to stand idle for 10 days with 0.3 pCi/cc Xe-127 concen-tration. When the calibration resumed, the response of the beta scintillatordid not decrease in the expected proportions. An investigation indicated thatboth the inner and outer mylar sheets that cover the plastic scintillator hadadsorbed Xe-127 gas.Although the levels of activity used in this calibration were much higher thanthose normally encountered, the noble gas adsorption noted on the low range ofthe detection system could indicate a generic operational concern. The highbackground resulting from the adsorbed gas could cause overestimations in anyeffluent release calculations that are based on the monitor output. This isparticularly true if low-level monitoring is resumed following either a largeactivity excursion (3 or 4 orders of magnitude above normal) or an extendedmoderate increase (1 order of magnitude for a week or more). Following suchreleases the monitor should be purged and a new background taken. It should benoted that this gas adsorption phenomenon is probably not unique to SPING-4monitoring systems. Other manufacturers of plastic scintillation detectors usesimilar construction techniques. Any effluent monitor that employs a plasticscintillation detector may experience the same difficulties.

IN 86-30April 29, 1986 No specific action or written response is required by this information notice.If you have any questions about this matter, please contact the RegionalAdministrator of the appropriate regional office or this office.ward L. Jordan Directori Division of Emergency Preparednesand Engineering ResponseOffice of Inspection and Enforcement

Technical Contact:

Roger L. Pedersen, IE(301)492-9425James E. Wigginton, IE(301)492-4967Attachment:List of Recently Issued IE Information Notices

Attachment 1IN 86-30April 29, 1986LIST OF RECENTLY ISSUEDIE INFORMATION NOTICESInformation Date ofNotice No. Subject Issue Issued to86-2986-2886-27Effects of Changing ValveMotor-Operator SwitchSettingsUnauthorized Transfer andLoss of Control of Indus-trial Nuclear GaugesAccess Control at NuclearFacilitiesPotential Problems InGenerators Manufactured ByElectrical ProductsIncorporatedTraceability And MaterialControl Of Material AndEquipment, ParticularlyFasteners4/25/864/28/864/21/864/17/864/11/8686-2686-25All power reactorfacilities holdingan OL or a CPAll licensees author-ized to possess anduse industrial nucleargauges.All power reactorfacilities holdingan OL or CP, researchand nonpower reactorfacilities, and fuelfabrication & pro-cessing facilitiesAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CP; researchand test reactorfacilities; fuelcycle licensees andPriority 1 materiallicenseesAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CP andresearch and testreactors86-24Respirator Users Notice: 4/11/86Increased Inspection FrequencyFor Certain Self-ContainedBreathing Apparatus AirCylinders86-23Excessive Skin Exposures DueTo Contamination With HotParticlesUnderresponse Of RaditionSurvey Instrument To HighRadiation Fields4/9/863/31/8686-22OL = Operating LicensePIr r,.^-,4>. n,.