ML20195H899

Insp Rept 50-184/98-202 on 981006-07.No Violations Noted. Major Areas Inspected:Mgt Response to non-safety Related Leak

ML20195H899
Person / Time
Site:	National Bureau of Standards Reactor
Issue date:	11/16/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20195H892	List: ML20195H888 ML20195H899
References
50-184-98-202, NUDOCS 9811240141
Download: ML20195H899 (6)

See also: IR 05000184/1998202

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U.S. NUCLEAR REGULATORY COMMISSION

Docket No: 50-184

License No: TR-5 )

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Report No: 1998202 I

. Licensee: U. S. Department of Commerce j

Facility: National Bureau of Standards Reactor

Location: National Institute of Standards and Technology

a.- Gaithersburg, Maryland 20899

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Dates: October 6-7,1998

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Inspector: Thomas F. Dragoun, Reactor inspector j

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Approved by: Seymour H. Weiss, Director -

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Non-Power Reactors and Decommissioning  !

Project Directorate i

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9811240141 981116 1

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~ EXECUTIVE SUMMARY  !

NationalInstitute of Standards and Technology ,

NRC Inspection Report No. 50 184/1998202

l Management response to a non-safety related leak was conservative. Efforts to locate and

isolate the leak were detailed and comprehensive. Radiation protection of workers was

appropriate.

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Reoort Details

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Summarv of Plant Status

A small, sporadic leak of heavy water was detected in the thermal column area beginning )

September 2,1998. On Septemt ar 4, the reactor was shutdown and defueled. The -l.

graphite blocks were removed from the thermal column to allow access to the small heavy

water tank at the head of the column. Attempts to locate the leak included visual l

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inspections with a fiber optic camera and helium sniffing after the fluid system was

pressurized with gas.

1.0 Maintenance Activities

. a. insoection Scone Unsoection Procedure 39745)

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The inspector reviewed:

e reactivity effects of the leak,

e proposed repairs, and-

e safety evaluations,

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b. Observations and Findinas

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The inspector noted that the reactivity worth of the heavy water tank suspected to

be leaking was not discussed in the Final Safety Analysis Report. Facility staff

stated that experience indicated that the worth was negligible. This was attributed

to the thickness of moderator / reflector between the fuel and the tank.

l The leak was not located during this inspection and additional attempts were

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planned. A " repair team" consisting of senior reactor operators, engineering staff,

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. and supervisors was designated to find the leak.. All efforts seemed to be well

l planned and coordinated with adequate attention to personnel safety.

!- Management indicated th'at efforts to locate the leak will continue until all  !

possibilities are evaluated. The facility has been shut down for a month thus far

and additional time was planned. Provisions were made to collect and monitor

leakage after return to routine operations if the leak reappears. j

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l c. Conclusions- l

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l The leak was not safety significant. Licensee actions taken in response to the leak j

! were conservative.

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2.0 Radiation Protection

a. Inspection Scope (Inspection Procedure 83743)

The inspector reviewed:

o radiological conditions and controls,

e use of a radiation work permit,

e personnel exposures, and

e ALARA practices,

b. Observations and Findiaga

The irradiated fuel in the core was allowed to decay for 10 days prior to transfer to

the spent fuel pool. This exceeded the minimum decay time specified in TS 3.7.

Disassembly of the thermal column resulted in a high radiation area inside the

vacant opening. Removed components had low level of surface contamination.

Personnel access to the high radiation area was controlled by locking the

confinement building doors. This satisfied requirements in 10 CFR 20.1601.

Caution signs, postings, and barriers met the requirements in 10 CFR 20 Subpart J.

A radiation work permit (RWP) was used to specify the radiological controls and

precautions during the search for the leak. The inspector noted that these appeared

appropriate for the conditions recorded during a recent survey. However, the survey

data was not recorded on the RWP nor was detailed data attached to the RWP.

10 CFR 19.12 requires that workers be instructed regarding radiological conditions

and precautionary measures to be taken. The RSO stated that this is done verbally

by HPs prior to any work. Licensee managerrent stated that adding the results of

radiation survey data to the RWP form will be considered. ,

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Personnel doses recorded for this work were below NRC limits and seemed I

reasonable. ALARA precautions included installation of a custom lead shield

fabricated to fit inside the thermal column and another special shield for

reinstallation of the graphite blocks into the thermal column. In a concurrent  :

activity to replace beam port shutters, the licensee was taking advantage of the I

lower dose rates at port BT 5 to train workers and develop techniques for similar

work planned for other beam ports. Attention and support for ALARA appeared

adequate. j

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c. Conclusions

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Radiation protection practices met regulatory requirements. j

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.X1 Exit interview (Inspection Procedure 30703)  :

The inspector presented the inspection results to members of licensee management at the

l conclusion of the inspection on October 7,1998. The licensee acknowledged the findings

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PARTIAL LIST OF PERSONS CONTACTED

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Licensee

W. Mueller, Senior Reactor Operator

T. Raby, Chief Nuclear Engineer

J. Rowe, Chief, Reactor Radiation Division

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INSPECTION PROCEDURES USED ,

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IP 30703: ENTRANCE AND EXIT INTERVIEWS

IP 39745 CLASS I NON-POWER REACTORS ORGANIZATION AND OPERATIONS

AND MAINTENANCE ACTIVITIES

IP 83743 CLASS I NON-POWER REACTORS RADIATION PROTECTION

ITEMS OPENED, CLOSED, AND DISCUSSED

Ooened

None

Closed

None

LIST OF ACRONYMS USED

CFR Code of Federal Regulations

HPs Health Physicists

IP inspection procedure

NRC Nuclear Regulatory Commission

RWP Radiation Work Permit

SAR Safety Analysis Report

TS Technical Specifications

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