Information Notice 2005-28, Inadequate Test Procedure Fails to Detect Inoperable Criticality Accident Alarm Horns

Inadequate Test Procedure Fails to Detect Inoperable Criticality Accident Alarm Horns

ML052720579
Person / Time
Issue date:	10/31/2005
From:	Hiland P, Pierson R NRC/NMSS/FCSS, NRC/NRR/DIPM/IROB
To:
References
IN-05-028
Download: ML052720579 (7)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555 October 31, 2005 NRC INFORMATION NOTICE 2005-28: INADEQUATE TEST PROCEDURE FAILS TO

DETECT INOPERABLE CRITICALITY ACCIDENT

ALARM HORNS

ADDRESSEES

All licensees authorized to possess a critical mass of special nuclear material.

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform

addressees of a concern related to criticality alarms at fuel fabrication facilities, nuclear power

plants, and other facilities processing, storing, or handling critical masses of fissile material. It

is expected that licensees will review this information and consider actions, as appropriate, to

avoid similar problems. Suggestions contained in this IN are not NRC requirements; therefore, no specific action nor written response is required.

DESCRIPTION OF CIRCUMSTANCES

Under 10 CFR 70.24 and 10 CFR 76.89, certain licensees possessing, storing, or handling

critical masses of fissile material are required to maintain a criticality accident alarm system that

is capable of detecting the minimum accident of concern in fissile material operations and

annunciating a clearly audible signal that will cause the immediate evacuation of affected

persons to a safe location. All areas of fuel cycle facilities licensed under these regulations are

required to be covered by event detection and alarm signaling devices. In addition, certain 10 CFR Part 50 licensees are required, as part of their licensing basis for new and spent fuel

storage, to maintain a criticality accident alarm system in accordance with the 10 CFR Part 70

regulations.

A fuel cycle licensee conducted monthly tests of the site criticality accident alarm system by

sounding the horns while designated employees listened for the alarm. The licensee relied on

all employees to report questionable alarm audibility. Subsequent to a recent routine criticality

alarm system test at the facility, a licensee maintenance manager questioned audibility and

directed maintenance staff to check all criticality accident alarm horns in the system. The horn

operability check resulted in the discovery that eight horns were inoperable and that the

criticality alarm system was inaudible at several exterior locations.

The fuel cycle licensee in this situation used multiple, independent criticality accident alarm

detector/annunciator systems to accomplish coverage of the facility. The licensee facility was

physically large, and used several independent criticality alarm systems. Multiple, independent

criticality alarm systems were used because the licensee desired that employees only evacuate

if they would be affected by the criticality event detected as defined by horn audibility. Detector

and annunciator (horn) coverage of exterior areas was not fully redundant, resulting in the

necessity for individual systems to be able to annunciate events in their area of coverage

without the assistance of other systems. Four out of five horns on one exterior system became

inoperable over time so that an alarm from that system could not be heard in a large portion of

its area of coverage, including locations with high ambient noise levels and the interior of two

buildings containing non-fissile operations.

DISCUSSION

The criticality alarm concern arises when licensees fail to detect inoperable criticality alarm

system annunciators (horns) during routine testing, and an inaudible criticality alarm situation is

not corrected. Two factors contributed to the problem. First, the test procedure sounded horns

in groups and did not routinely check individual horns for operability. Inoperable horns were not

always detected during the criticality alarm routine tests and, in fact, could go undetected until

many horns were inaudible and a large part of the facility was not receiving an audible alarm.

Second, the licensee relied on all employees to report inaudibility, but employees did not fully

understand requirements for criticality alarm horn response during system audibility testing. In

fact, employees were trained to react only to audible alarms. The affected buildings involved

intermittent work operations so that, even though the criticality alarm system horns involved

were rated at approximately 100 decibels, employees working in the area did not recognize that

the horns never sounded.

The NRC concern about this issue is that failure to adequately test a criticality alarm system for

audibility may cause an inaudible condition to go undetected for an indefinite amount of time.

This event likely occurred because licensee training did not result in employees understanding

that inoperable horns in a work area were required to be reported and testing procedures did

not result in detection and correction of inoperable horns.

Failure to maintain audibility of the criticality alarm system exposes licensees to the possibility

that affected employees will not evacuate during an actual criticality event. NRC inspections of

criticality alarm systems typically include review of criticality accident alarm audibility test

procedures, employee emergency response training, criticality accident alarm detector/

annunciator coverage, and criticality accident alarm outage procedures.

CONTACT

This information notice does not require any specific action or written response. Please direct

any questions about this matter to the technical contact below, or the appropriate

regional office.

/RA/ /RA/

Patrick L. Hiland, Chief Robert C. Pierson, Director

Reactor Operations Branch Division of Fuel Cycle Safety

Division of Inspection Program Management and Safeguards

Office of Nuclear Reactor Regulation Office of Nuclear Material Safety

and Safeguards

Dennis Morey, NMSS

301-415-6107 E-mail: dcm@nrc.gov

Attachment: List of Recently Issued NMSS Generic Communications

CONTACT

This information notice does not require any specific action or written response. Please direct

any questions about this matter to the technical contact below, or the appropriate

regional office.

/RA/ /RA/

Patrick L. Hiland, Chief Robert C. Pierson, Director

Reactor Operations Branch Division of Fuel Cycle Safety

Division of Inspection Program Management and Safeguards

Office of Nuclear Reactor Regulation Office of Nuclear Material Safety

and Safeguards

Dennis Morey, NMSS

301-415-6107 E-mail: dcm@nrc.gov

Attachment: List of Recently Issued NMSS Generic Communications

ADAMS ACCESSION #: ML052720579 OFC FCSS/TSG Tech ED FCSS/TSG NRR NRR

NAME DMorey:dw Ekraus: by fax MGalloway VHodge JWermiel

DATE 9/ 30 /05 10/ 04 /05 10/ 06 /05 10/ 24 /05 10/ 24 /05 OFC NRR NRR NRR FCSS

NAME IJung MJRoss-Lee PHiland RPierson

DATE 10/ 27 /05 10/ 27 /05 10/ 28 /05 10/ 31 /05

Attachment Recently Issued NMSS Generic Communications

Date GC No. Subject

Addressees

2/11/05 BL-05-01 Material Control and All holders of operating licenses

Accounting at Reactors and for nuclear power reactors, Wet Spent Fuel Storage decommissioning nuclear power

Facilities reactor sites storing spent fuel in

a pool, and wet spent fuel storage

sites.

8/25/05 RIS-05-18 Guidance for Establishing All licensees, applicants for

and Maintaining a Safety licenses, holders of certificates of

Conscious Work compliance, and their contractors

Environment subject to NRC authority

8/10/05 RIS-05-16 Issuance of NRC All licensees and certificate

Management Directive 8.17, holders.

Licensee Complaints

Against NRC Employees

8/3/05 RIS-05-15 Reporting Requirements for All material licensees possessing

Damaged Industrial industrial radiographic equipment, Radiographic Equipment regulated under 10 CFR Part 34.

7/13/05 RIS-05-13 NRC Incident Response and All licensees and certificate

the National Response Plan holders.

7/11/05 RIS-05-12 Transportation of Licensees authorized to possess

Radioactive Material radioactive material that equals or

Quantities of Concern NRC exceeds the threshold values in

Threat Advisory and the Additional Security Measures

Protective Measures System (ASM) for transportation of

Radioactive Material Quantities of

Concern (RAMQC) under their 10

CFR Part 30, 32, 50, 70, and 71 licenses and Agreement State

licensees similarly authorized to

possess such material in such

quantities under their Agreement

State licenses.

7/11/05 RIS-05-11 Requirements for Power All holders of operating licenses

Reactor Licensees in for nuclear power reactors and

Possession of Devices generally licensed device

Subject to the General vendors.

License Requirements of 10

CFR 31.5

Attachment Recently Issued NMSS Generic Communications

Date GC No. Subject

Addressees

6/10/05 RIS-05-10 Performance-Based All industrial radiography

Approach for Associated licensees and manufacturers and

Equipment in 10 CFR 34.20 distributors of industrial

radiography equipment.

4/18/05 RIS-05-06 Reporting Requirements for All material licensees possessing

Gauges Damaged at portable gauges, regulated under

Temporary Job Sites 10 CFR Part 30.

4/14/05 RIS-05-04 Guidance on the Protection All holders of operating licenses

of Unattended Openings or construction permits for nuclear

that Intersect a Security power reactors, Boundary or Area research and test reactors, decommissioning reactors with

fuel on site, Category 1 fuel cycle

facilities, critical mass facilities, uranium conversion facility, independent spent fuel storage

installations, gaseous diffusion

plants, and certain other material

licensees.

2/28/05 RIS-05-03 10 CFR Part 40 Exemptions All persons possessing aircraft

for Uranium Contained in counterweights containing

Aircraft Counterweights - uranium under the exemption in

Storage and Repair 10 CFR 40.13(c)(5).

10/07/05 IN-05-27 Low Dose-Rate Manual All medical licensees.

Brachytheraphy Equipment

Related Medical Events

7/29/05 IN-05-22 Inadequate Criticality Safety All licensees authorized to

Analysis of Ventilation possess a critical mass of special

Systems at Fuel Cycle nuclear material.

Facilities

6/23/05 IN-05-17 Manual Brachytherapy All medical licensees authorized

Source Jamming to possess a Mick applicator.

Attachment Recently Issued NMSS Generic Communications

Date GC No. Subject

Addressees

5/17/05 IN-05-13 Potential Non-conservative All licensees using the Keno-V.a

Error in Modeling Geometric criticality code module in

Regions in the Standardized Computer Analyses

Keno-v.a Criticality Code for Licensing Evaluation (SCALE)

software developed by Oak Ridge

National Laboratory (ORNL)

5/17/05 IN-05-12 Excessively Large Criticality All licensees authorized to

Safety Limits Fail to Provide possess a critical mass of special

Double Contingency at Fuel nuclear material.

Cycle Facility

4/7/05 IN-05-10 Changes to 10 CFR Part 71 All 10 CFR Part 71 licensees and

Packages certificate holders.

4/1/05 IN-05-07 Results of HEMYC Electrical All holders of operating licenses

Raceway Fire Barrier for nuclear power reactors, except

System Full Scale Fire those who have

Testing permanently ceased operations

and have certified that fuel has

been permanently removed

from the reactor vessel, and fuel

facilities licensees.

3/10/05 IN-05-05 Improving Material Control All licensees authorized to

and Accountability Interface possess a critical mass of special

with Criticality Safety nuclear material.

Activities at Fuel

Cycle Facilities

Note: NRC generic communications may be found on the NRC public website, http://www.nrc.gov, under Electronic Reading Room/Document Collections.