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 NRC/IE
To:
References
IN-86-030, NUDOCS 8604280122
Download: ML031220651 (4)

SSINS No.: 6835 IN 86-30

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 April 29, 1986 IE INFORMATION NOTICE NO. 86-30: DESIGN LIMITATIONS OF GASEOUS EFFLUENT

MONITORING 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 in

the use of Eberline's SPING-4 (system particulate iodine and noble gas) gaseous

effluent monitoring systems. The first deals with the limitations of the

detection capability of the SPING-4 monitoring system. Some licensees are

incorrectly 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 could

interfere with routine operational low-level monitoring.

It is expected that recipients will review this information for applicability

to their facilities and consider actions, if appropriate, to preclude problems

related 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 overlapping

channels, the noble gas (NG) monitor has a detection capability of 10-7 to 105 pCi/cc (Xe-133 equivalent). The low-range channel employs a beta scintillation

detector. 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 and

measure concentrations of NG fission products in plant effluents (up to

lo5 pCi/cc for undiluted containment exhaust) during and following an accident.

Recent NRC regional inspections of NUREG-0737 implementation indicate that

8604280122

IN 86-30

April 29, 1986 some licensees have installed SPING-4 monitors and mistakenly consider them

adequate to meet all of the requirements of Item II.F.1.1. Although the

SPING-4 does have an upper detection capability of 105 pCi/cc, its associated

microcomputer is vulnerable to radiation damage from a total integrated dose

greater than 1000 rads. Therefore, it is unlikely the SPING-4 would survive

the course of an accident. Eberline has indicated that the SPING-4 was

designed primarily as a normal-range monitor with extended capabilities for

brief 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 in

conjunction with an accident monitor (with a remote microprocessor) such as

Eberline's model AXM-1. The accident monitor comes on line when excessively

high activity levels are sensed while the SPING-4 isolates itself and goes into

a purge cycle.

Noble Gas Adsorption:

Eberline has noted noble gas adsorption with the plastic scintillator while

performing a SPING-4 calibration. This calibration compared the SPING-4 output

with 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 scintillator

did not decrease in the expected proportions. An investigation indicated that

both the inner and outer mylar sheets that cover the plastic scintillator had

adsorbed Xe-127 gas.

Although the levels of activity used in this calibration were much higher than

those normally encountered, the noble gas adsorption noted on the low range of

the detection system could indicate a generic operational concern. The high

background resulting from the adsorbed gas could cause overestimations in any

effluent release calculations that are based on the monitor output. This is

particularly true if low-level monitoring is resumed following either a large

activity excursion (3 or 4 orders of magnitude above normal) or an extended

moderate increase (1 order of magnitude for a week or more). Following such

releases the monitor should be purged and a new background taken. It should be

noted that this gas adsorption phenomenon is probably not unique to SPING-4 monitoring systems. Other manufacturers of plastic scintillation detectors use

similar construction techniques. Any effluent monitor that employs a plastic

scintillation detector may experience the same difficulties.

IN 86-30

April 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 Regional

Administrator of the appropriate regional office or this office.

ward L. Jordan Director

i Division of Emergency Preparednes

and Engineering Response

Office of Inspection and Enforcement

Roger L. Pedersen, IE

(301)492-9425 James E. Wigginton, IE

(301)492-4967 Attachment:

List of Recently Issued IE Information Notices

Attachment 1 IN 86-30

April 29, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-29 Effects of Changing Valve 4/25/86 All power reactor

Motor-Operator Switch facilities holding

Settings an OL or a CP

86-28 Unauthorized Transfer and 4/28/86 All licensees author- Loss of Control of Indus- ized to possess and

trial Nuclear Gauges use industrial nuclear

gauges.

86-27 Access Control at Nuclear 4/21/86 All power reactor

Facilities facilities holding

an OL or CP, research

and nonpower reactor

facilities, and fuel

fabrication & pro- cessing facilities

86-26 Potential Problems In 4/17/86 All power reactor

Generators Manufactured By facilities holding

Electrical Products an OL or CP

Incorporated

86-25 Traceability And Material 4/11/86 All power reactor

Control Of Material And facilities holding

Equipment, Particularly an OL or CP

Fasteners

86-24 Respirator Users Notice: 4/11/86 All power reactor

Increased Inspection Frequency facilities holding

For Certain Self-Contained an OL or CP; research

Breathing Apparatus Air and test reactor

Cylinders facilities; fuel

cycle licensees and

Priority 1 material

licensees

86-23 Excessive Skin Exposures Due 4/9/86 All power reactor

To Contamination With Hot facilities holding

Particles an OL or CP

86-22 Underresponse Of Radition 3/31/86 All power reactor

Survey Instrument To High facilities holding

Radiation Fields an OL or CP and

research and test

reactors

OL = Operating License

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