ML090120669

Use of Containment Atmosphere Gaseous Radioactivity Monitors as Reactor Coolant System Leakage Detection Equipment at Nuclear Power Reactors

ML090120669
Person / Time
Issue date:	01/29/2009
From:	Mcginty T Division of Policy and Rulemaking
To:
Hawes C, NRR/DPR/PGCB, 415-1316
References
RIS-09-002
Download: ML090120669 (6)

See also: RIS 2009-02

Text

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, DC 20555-0001

January 29, 2009

NRC REGULATORY ISSUE SUMMARY 2009-02

USE OF CONTAINMENT ATMOSPHERE GASEOUS RADIOACTIVITY

MONITORS AS REACTOR COOLANT SYSTEM LEAKAGE DETECTION

EQUIPMENT AT NUCLEAR POWER REACTORS

ADDRESSEES

All holders of operating licenses for nuclear power reactors except those who have permanently

ceased operations and have certified that fuel has been permanently removed from the reactor

vessel.

All current and potential applicants for a combined license, manufacturing license, standard

design certification, or standard design approval for a nuclear power plant under the provisions

of Title 10 of the Code of Federal Regulations, Part 52 (10 CFR), Licenses, Certifications, and

Approvals for Nuclear Power Plants.

All applicants for nuclear power plant construction permits and operating licenses under the

provisions of 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities.

INTENT

The U.S. Nuclear Regulatory Commission (NRC) is issuing this regulatory issue summary (RIS)

to communicate the NRC plan to address the situation created when some containment

atmosphere gaseous radioactivity monitors are unable to meet technical specification (TS)

requirements. The plan consists of integrating a streamlined license amendment process with

the use of enforcement discretion, where appropriate. This RIS requires no action or written

response on the part of an addressee.

BACKGROUND INFORMATION

In order to meet General Design Criterion 30, "Quality of reactor coolant pressure boundary," of

Appendix A to 10 CFR Part 50, licensees typically include RCS leakage detection equipment in

their plant designs because the equipment can be used to detect reactor coolant pressure

boundary (RCPB) leakage. A typical RCS leakage detection system consists of a combination

of the following:

• a containment atmosphere particulate radioactivity monitoring system

• a containment atmosphere gaseous radioactivity monitoring system

• containment sump-level and sump-pump instrumentation

• containment cooler condensate monitoring instrumentation

ML090120669

RIS 2009-02

Page 2 of 5

Containment atmosphere gaseous radioactivity monitoring systems measure RCS leakage

indirectly by detecting airborne radioactivity released from RCS leakage. Response time is the

length of time required for these monitoring systems to detect a given volume of RCS leakage.

Response time is dependant on RCS radioactivity concentration, as well as other variables. For

a given volume of leakage, with all other variables held constant, a higher RCS radioactivity

concentration will yield a shorter response time for these monitoring systems. The design

analyses for the containment atmosphere gaseous radioactivity monitoring systems used in the

licensing bases for most plants typically assume a RCS radioactivity concentration

approximately equivalent to 0.1 percent failed fuel in the core. Improvements in fuel cladding

integrity and RCS chemistry controls have significantly reduced RCS radioactivity concentration

at most plants. As a result, the monitors for operating units may have longer response times

than they would with 0.1 percent failed fuel in the core because the actual RCS radioactivity

concentration is less than it would be with 0.1 percent failed fuel in the core.

Most plants have TS Limiting Conditions for Operation requirements for containment

atmosphere gaseous radioactivity monitoring systems used as part of RCS leakage detection

equipment. The TS requirements for the monitoring systems response times are based on the

design analysis that is part of a plants licensing basis. If the monitors fail to meet these

requirements, the monitors are inoperable. When the monitors are inoperable the licensee is

required to take remedial actions as permitted by their TS or to shut down the reactor.

Information Notice (IN) 2005-24, Nonconservatism in Leakage Detection Sensitivity

(ADAMS Accession No. ML051780073), communicated the issue created by differences

between actual and assumed RCS radioactivity concentrations to all licensees. The purpose of

IN 2005-24 was to have licensees review information related to problems with containment

atmosphere gaseous radioactivity monitors used as part of RCS leakage detection equipment

and consider appropriate actions as applicable to their plants. Information Notices do not

require any action by licensees.

In September 2008, NRC inspectors at the Diablo Canyon Power Plant identified a non-cited

violation for not complying with TS requirements for RCS leakage detection equipment. In

November 2008, the licensee for the Watts Bar Nuclear Plant and the Sequoyah Nuclear Plant

requested exigent license amendments from the NRC after taking remedial actions as permitted

by their TS because of a concern that the containment atmosphere gaseous radioactivity

monitor channels of the RCS leakage detection system were inoperable.

To address the issue, licensees working through the industry-sponsored Technical

Specifications Task Force (TSTF) have attempted to create generic TS changes, model License

Amendment Requests (LARs), model safety evaluations, and model proposed

no-significant-hazards consideration determinations using the NRC TS Consolidated Line Item

Improvement Process (CLIIP). See RIS 2000-10, Consolidated Line Item Improvement

Process For Adopting Standard Technical Specifications Changes for Power Reactors

(ADAMS Accession No. ML003693442) for more information on the NRC CLIIP.

RIS 2009-02

Page 3 of 5

SUMMARY OF ISSUE

Improvements in fuel cladding integrity and RCS chemistry controls result in lower RCS

radioactivity concentrations during operational activities, including situations where there is RCS

leakage. Thus, containment atmosphere gaseous radioactivity monitoring systems which are

designed on the basis of higher assumed RCS radioactivity concentrations will not provide

accurate indication of RCS leakage in the required length of time due to the longer response

time of the monitoring system, and must be considered inoperable.

The NRC considers the longer response times of the containment atmosphere gaseous

radioactivity monitors to be of very low safety significance. The monitors would still be able to

detect degradation in the RCPB long before components fail in a manner that would affect plant

safety. Additionally, plants also have multiple diverse and redundant methods available to

detect RCS leakage and to provide licensees with a means to detect significant RCPB

degradation and to take appropriate action to ensure the continued protection of public health

and safety. Finally, nuclear power plants are designed to provide adequate core cooling

following postulated loss-of-coolant accidents up to and including a break equivalent in size to

the double-ended rupture of the largest pipe in the RCS. This design feature, coupled with the

extremely low likelihood of unstable crack growth resulting in a loss-of-coolant accident, leads

the NRC to conclude that the risk significance of this issue is very low.

The NRC plans to address the issue of inoperable containment atmosphere gaseous

radioactivity monitoring systems in an integrated fashion by: (i) working with the TSTF to

develop revised generic TS for the monitoring system, and facilitating licensee implementation

of the revised generic TS through a streamlined license amendment process; and (ii) issuing

guidance on NRCs exercise of enforcement discretion involving inoperable containment

atmosphere gaseous radioactivity monitoring systems.

The NRC will review the generic TS changes that the TSTF proposes for pressurized-water

reactors (PWRs) and boiling-water reactors (BWRs). If the generic TS changes are found to be

acceptable, the NRC will make the generic model LARs, model safety evaluations, and model

no-significant-hazards consideration determinations available to licensees using the NRC CLIIP.

Licensees are free to submit LARs for TS changes to address the issue. If licensees deem

further action regarding the issue is unwarranted, they can choose to take no action.

On November 14, 2008, the TSTF submitted TSTF-513, Revise Operability Requirements and

Actions for RCS Leakage Instrumentation, to the NRC for review. TSTF-513 proposes generic

TS changes for PWRs. The TSTF plans to submit TSTF-514 to the NRC in January 2009.

TSTF-514 will propose generic TS changes for BWRs. Licensees are free to submit LARs to

address the issue using TSTF-513 or TSTF-514; or they can propose alternative solutions.

In certain circumstances involving inoperable containment atmosphere gaseous radioactivity

monitoring systems, enforcement discretion is available. Specific guidance for this enforcement

discretion is described in EGM-09-001 (ADAMS Accession No. ML090300467) and is available

on the NRCs web site at www.nrc.gov.

RIS 2009-02

Page 4 of 5

BACKFIT DISCUSSION

The intent of this RIS is to inform addressees of the NRCs plan to address the failure of

containment atmosphere gaseous radioactivity monitors used as RCS leakage detection

equipment to meet TS requirements.

The staff is not imposing any new positions on licensees. This RIS is not providing any new

regulatory positions. This RIS only conveys the NRCs plan to address the issue of RCS

leakage detection equipment failing to meet TS requirements because of the difference between

actual and assumed RCS radioactivity concentrations. This RIS requires no action or written

response and, therefore, is not a backfit under 10 CFR 50.109, Backfitting. Consequently, the

staff did not perform a backfit analysis.

FEDERAL REGISTER NOTIFICATION

A notice of opportunity for public comment on this RIS was not published in the Federal Register

because it is informational and pertains to a staff position that does not represent a departure

from current regulatory requirements and practice. However, a public meeting to discuss this

RIS was held on January 8, 2009. The meeting summary is available under ADAMS Accession

No. ML090130583. The NRC intends to work with industry representatives, members of the

public, and other stakeholders in developing final guidance and in modifying related guidance

documents.

CONGRESSIONAL REVIEW ACT

This RIS is not a rule as designated by the Congressional Review Act (5 U.S.C. §§ 801-808)

and, therefore, is not subject to the Act.

PAPERWORK REDUCTION ACT STATEMENT

This RIS does not contain any information collections and, therefore, is not subject to the

requirements of the Paperwork Reduction Act of 1995 (44 U.S.C. 3501, et seq.).

PUBLIC PROTECTION NOTIFICATION

The NRC may not conduct or sponsor, and a person is not required to respond to, a request for

information or an information collection requirement unless the requesting document displays a

currently valid OMB control number.

RIS 2009-02

Page 5 of 5

CONTACT

Please direct any questions about this matter to the technical contact listed below or to the

appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

/RA by Theodore R. Quay For/

Timothy J. McGinty, Director

Division of Policy and Rulemaking

Office of Nuclear Reactor Regulation

Technical Contact: Matthew Hamm, NRR

301-415-1472

e-mail: matthew.hamm@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site,

http://www.nrc.gov, under Electronic Reading Room/Document Collections.

RIS 2009-02

Page 5 of 5

CONTACT

Please direct any questions about this matter to the technical contact listed below or to the

appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

/RA by Theodore R. Quay For/

Timothy J. McGinty, Director

Division of Policy and Rulemaking

Office of Nuclear Reactor Regulation

Technical Contact: Matthew Hamm, NRR

301-415-1472

e-mail: matthew.hamm@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site,

http://www.nrc.gov, under Electronic Reading Room/Document Collections.

ADAMS ACCESSION No. ML090120669

OFFICE ITSB:DIRS Tech Editor BC:ITSBDIRS D:DIRS PSPB DPR BC:PSPB DPR

NAME MHamm via email RElliott FBrown JWilliams SRosenberg

MCheok for DNelson for

DATE 12/19/2008 12/15/2008 1/12/2009 1/12/2009 12/30/2008 12/30/2008

OFFICE D:DSS D:DORL RI:DRP:D RII:DRP:D RIII:DRP:D RIV:DRP:D

NAME WRuland for JGiitter DLew via LWert via CPederson DChamberlain

email email via email via email

DATE 1/12/2009 12/30/2008 1/15/2009 1/14/2009 1/13/2009 1/15/2009

OFFICE D:DCI BC:CHPB OE OGC (NLO) OGC (CRA)

D: DCIP/NRO

DCIP

NAME MEvans TFrye GTracy DStarkey BJones NSanchez

CHinson for via email via email

DATE 1/15/2009 01/07/2009 01/08/2009 1/14/2009 01/27/2009 1/28/2009

OFFICE PMDA OIS LA:PGCB PGCB BC: PGCB D:DPR

NAME LHill GTrussell CHawes SStuchell MMurphy TMcGinty TRQ

for

DATE 01/05/2009 01/07/2009 1/28/2009 1/28/2009 1/29/2009 1/29/2009

OFFICIAL RECORD COPY