ML20195H899
| ML20195H899 | |
| Person / Time | |
|---|---|
| Site: | National Bureau of Standards Reactor |
| Issue date: | 11/16/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20195H892 | List: |
| 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
. Licensee:
U. S. Department of Commerce
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Facility:
National Bureau of Standards Reactor
Location:
National Institute of Standards and Technology
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Gaithersburg, Maryland 20899
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Dates:
October 6-7,1998
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Inspector:
Thomas F. Dragoun, Reactor inspector
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Approved by:
Seymour H. Weiss, Director
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Non-Power Reactors and Decommissioning
Project Directorate
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9811240141 981116
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ADOCK 05000194
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~ EXECUTIVE SUMMARY
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NationalInstitute of Standards and Technology
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NRC Inspection Report No. 50 184/1998202
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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
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September 2,1998. On Septemt ar 4, the reactor was shutdown and defueled. The
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graphite blocks were removed from the thermal column to allow access to the small heavy
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water tank at the head of the column. Attempts to locate the leak included visual
inspections with a fiber optic camera and helium sniffing after the fluid system was
pressurized with gas.
1.0 Maintenance Activities
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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.
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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
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planned and coordinated with adequate attention to personnel safety.
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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.
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c.
Conclusions-
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The leak was not safety significant. Licensee actions taken in response to the leak
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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
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
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.
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c.
Conclusions
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Radiation protection practices met regulatory requirements.
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Exit interview (Inspection Procedure 30703)
The inspector presented the inspection results to members of licensee management at the
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conclusion of the inspection on October 7,1998. The licensee acknowledged the findings
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PARTIAL LIST OF PERSONS CONTACTED
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
CLASS I NON-POWER REACTORS ORGANIZATION AND OPERATIONS
AND MAINTENANCE ACTIVITIES
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
Health Physicists
IP
inspection procedure
NRC Nuclear Regulatory Commission
RWP Radiation Work Permit
Safety Analysis Report
TS
Technical Specifications
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