ML20236M481
| ML20236M481 | |
| Person / Time | |
|---|---|
| Site: | University of Virginia |
| Issue date: | 08/04/1987 |
| From: | Burnett P, Caldwell J, Hosey C, Wright F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20236M455 | List: |
| References | |
| 50-062-87-03, 50-62-87-3, NUDOCS 8708110084 | |
| Download: ML20236M481 (16) | |
See also: IR 05000062/1987003
Text
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UNITED STATES
en Recoq' 'o
NUCLEAR REGULATORY COMMISSION
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REGION ll
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101 MARlETTA STRE ET, N.W.
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ATLANT A, GEORGI A 30323
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AUG 0 0 o37
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Report No.:
50-62/87-03
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Licensee:
University of Virginia
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Charlottesville, VA 22901
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Docket No.: 50-62
License No.: R-66
Facility Name: University of Virginia Reactor UVAR
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Inspection Conducted:
July 6-8, 1987 and July 15-17, 1987
Inspectors:
b41
P/t/07
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F. N. Wright
Date Signed
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P. T. Burnett
Date Signed
DA lMe
F/vIt7
J. Caldwell
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Date Sign 6d
Approved by:
M
?[T [/7
C. Hosey', SectiontChief
Date Signed
Division of Radiation Safety and Safeguards
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SUMMARY
Scope:
This special, unannounced inspection involved onsite inspection in the
area of review of events associated with a potential overexposure of personnel
in the licensee's neutron radiography facility.
Results:
Four violations - failure to perform a safety evaluation, failure to
perform an adequate survey, failure to have procedures, and failure to document
a survey, were identified.
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REPORT DETAILS
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1.
Persons Contacted
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Licensee Employees
- R. Allen, Director, Environmental Health and Safety
- +P. E. Benneche, Supervisor, Reactor Operations
- +J. S. Brenizer, Jr. , Assistant Professor, Nuclear Engineering Department
+G. D. Conley, Senior Reactor Operator
- +B. Copcutt, Radiation Safety Officer, Environmental Health and Safety
D. W. Freeman, Research Scientist
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K. M. Gibbs, Graduate Research Assistant
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- +0. T. Hale, Reactor Health Physicist
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R. O. Johnson, Graduate Research Assistant
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- J. L. Meen, Chairman, Reactor Safety Committee
- +R. U. Mulder, Director, Reactor Facility
- +T. G. Williamson, Chairman, Department of Nuclear Engineering
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+J. P. Farrar, Reactor Administrator
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+B. Hosticka, Research Scientist
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K. R. Lawless, Member, Reactor Safety Committee
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- Attended exit interview conducted July 8,'1987
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+ Attended exit interview conducted July 17, 1987
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2.
Exit Interview
The inspection scope and findings were summarized on July 8, and July 17,
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1987, with those persons indicated in Paragraph 1 above.
The inspector
described the areas inspected and discussed in detail the inspection
findings.
On July 8, five apparent violations including failure to
conduct adequate radiation surveys, failure to control access to high
radiation areas, failure to post a high radiation area, failure to
document a radiation survey, and failure to have procedures for periodic
surveillance of a radiation detection instrument were discussed in detail.
On July 17, the inspector informed licensee management of two additional
violations for failure to perform a safety evaluation and to have approved
written procedures for construction, operation, and modifications to the
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neutron rMiography facility.
The licensee took no exceptions to the
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apparent v:4ation concerning failure to document a survey. The licensee
believed that documenting the survey performed in the blockhouse was et
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required.
The licensee did not identify as proprietary any of the
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materials provided to or reviewed by the inspectors during this
inspection.
Subsequent to the inspection, a review of the apparent violations by NRC
management has resulted in combining the violations for failure to conduct
an adequate survey, failure to control access to a high radiation area and
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failure to post a high radiation area, into a single violation for failure
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to perform adequate surveys.
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3.
Onsite Followup of Nonroutine Events (92700)
On July 2, 1987, the licensee notified the NRC that four or five persons
working in the licensee's neutron radiography facility could have received
exposures in excess of 5 rem.
The inspectors discussed the exposure and management controls for work in
the neutron radiography blockhouse (NRB) with licensee representatives-
reviewed records of su rveys , dose calculations, personnel exposure
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reports, and training records; observed facility modifications in
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progress; observed a reactor startup to full power; interviewed licensee
students and employees working in the NRB; and reviewed the licensee's
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standard operating procedures.
Based on the review of records and
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interviews, the inspectors determined the following sequence of events.
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The licensee conducts research, experiments, and performs tests for
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various clients utilizing thermal neutrons from the nuclear reactor. The
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neutrons are allowed to pass through the biological shield via a beam
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port.
The beam port tube is equipped with a controllable water filled
shield on the front of the tube (end near core) and a beam collimator on
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the other end.
The collimator is designed to reduce the gamma photon
constituent in the beam and produce a monoenergetic 0.4 electrons volt
(ev) neutron beam.
The licensee modified the beam port in 1983. The modifications were made
to allow the setup and disassembly of experiments without having to raise
and lower reactor power levels.
This modification involved the installation of a closed cycle fill and
drain system for operation of the floodable section of the beam port
(shield).
A high density concrete shield blockhouse was also constructed
around the beam port to protect personnel working in the facility when the
port shield was open and the reactor operating.
The licensee installed a
door and lock on the blockhouse to control access.
The licensee also
installed two monitors to determine when the beam port shield was drained
or open.
The two monitors consisted of a neutron radiation detector in
the blockhouse and a fluid detector on the water shield system.
The
shield fluid monitor and the neutron detector were connected to a lamp
sign above the blockhouse access door.
A signal from either would cause
the lamp to come on indicating " beam open."
There was also an alarm on
the door that would sound an audible alarm when the door was opened.
When the reactor is at full power (2 megawatts (MW)) and the beam shield
drained the beam delivers a dose rate of 180 Rems per hour in the
blockhouse.
The licensee's procedure for controlling access to the
blockhouse consisted of keeping the door to the blockhouse locked and
using calibrated portable survey instruments by persons entering the area
when the " beam open" light was on.
On June 17, 1987, the licensee began modifications to the NRB in order to
make the blockhouse more suitable for planned experiments.
The blockhouse
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modifications included raising the height of the blockhouse ceiling, and
installing additional shielding on the roof and at the blockhouse door.
During modifications the licensee curtailed all neutron radiography work
in the blockhouse.
In the two week period between June 17 and July 2, the
licensee removed the door from the blockhouse, disconnected the door's
audible alarm, and disconnected the beam shield water monitor and neutron
detector.
Surveys performed by the licensee prior to taking these actions
indicated radiation levels in the blockhouse were less than 2 mrem / hour.
All individuals working in the NRB were issued Beta-gamma film badges,
while those individuals working in neutron radiation areas were issued
neutron monitoring devices.
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On the morning of July 1, 1987, the facility health physicist performed a
radiation survey in the NRB and the radiation levels in the facility were
less than 2 mrem / hour.
By July 2, 1987, the licensee had modified the blockhouse wails, installed
the door, raised the ceiling, installed shielding on the roof, and had
relocated the controls for the water shield fill and drain pump.
On the morning of July 2, the facility Health Physicist issued two audible
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self reading dosimeters to individuals working on the blockhouse
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modifications.
The licensee was in the process of wiring lights and
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working on a sample transport system that would allow material to be moved
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in and out of the neutron beam.
The shield water monitor and the neutron
detector had not been reconnected.
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At approximately 1:30 p.m. on July 2, one of the workers assigned a
audible dosimeter entered the blockhouse.
The audible signal from the
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dosimeter indicated high radiation levels were present in the blockhouse.
The individual was in the area for about 30 seconds.
The worker left the
area and notified management of the apparent problem.
A licensee
representative entered the area with a gamma survey instrument measured
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gamma radiation levels of about 500 mrem /hr in the blockhouse.
Licensee
management immediately secured the area and began an investigation.
Initial investigation findings indicated that the beam port shield had
been partially drained creating a high radiation area in the blockhouse.
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Prior to 1:30 p.m. on July 2, the reactor was at full power.
Since the
licensee did not have the capability of directly measuring the neutron
dose rates in the blockhouse at 100% power with the beam open, the
licensee left the shield water level as found (beam partially open) and
surveyed the room at 2.5% full power, 5% full power and 10% full power
betweer 3:00 p.m. and 3:30 p.m. on July 2, 1987.
The reactor was then
shut down for the day.
At 10% full power, the licensee measured
725 mrem / hour neutron and 50 mrem / hour gamma at the beam port.
The
licensee estimated that the dose rate at full power was 12 rem / hour
(neutron plus gamma radiation) at beam port when the high radiation area
was discovered.
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The licensee refilled the water shield.
The licensee estimated that the
shield had been open about 10%, base upon the amount of water required to
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fill tne beam shield. The licensee s cveyed the blockhouse again with the
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reactor at 10% power and with the wate chield fully closed and measured
dose rates of 2 mrem / hour neutron and 0.2 mrem / hour gamma.
The exact time that the bicek house became a high radiation area could not
be determined.
The licensee assumed that the shield had been open between
midday July 1, and about 1:30 p.m., July 2,1987, based on the fact that
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the facility health physicist had walked through the facility on the
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morning of July 1,1987, with a survey instrument and had not detected any
unusual radiation fields in the block house.
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Based upon the extrapolated dose rates, interviews with persons working in
the blockhouse, and the assumption that the high radiation area could have
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been present on July 1, the licensee initially estimated that personnel
exposures in excess of 50 rem may have occurred.
The licensee contacted
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their dosimetry vendor and made arrangements to have the workers dosimetry
analyzed.
The licensee reported the possible overexposure in accordance
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with 10 CFR 20.403 to the NRC at 5 p.m., on July 2, 1987.
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On July 3, the licensee's dosimetry vendor notified the licensee that the
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gamma radiation doses received by individuals who had entered the NRB in
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July 1987, were all less than 30 mrem.
On July 6, the vendor reported to
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the licensee that the neutron exposure for the three individuals wearing
neutron dosimetry was less than 10 mrem.
However, on July 14, the
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licensee informed the inspector that the written report from the dosimetry
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vendor indicated that the neutron doses for the three workers wearing
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neutron dosimeters were 20, 30 and 144 mrem.
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a.
Facility Modifications - Operations
(1) Beam Port Modifications
The operation and description of the beam port is described in
the Safety Analysis Report (SAR) Section 5.1.
SAR 5.1 states
that beam ports which are not in use will be filled with
concrete plugs.
The inspector determined that the beam ports had been modified in
1983.
Prior to the modifications, experiments were positioned in
front of the neutron beam port with the reactor shutdown.
The licensee would remove the shield plugs described in SAR 5.1,
secure the general work area for exposure control and raise the
reactor power level.
Upon completion of the experiment, the
licensee would shut the reactor down and enter the area to
repeat an experiment or secure the beam port by re-inserting the
beam port shields.
A licensee representative stated that
raising and lowering the reactor power levels for each neutron
beam port experiment was time consuming and impacted other
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operations. The licensee made the 1983 modifications to improve
facility efficiency.
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The modification involved the removal of the beam port shield
plugs, collimating and refining the beam, installation of a
closed cycle fill and drain system for operation of the
floodable section of the beam port, and a blockhouse or beam
catcher installed around the beam port to control radiation and
prevent excessive exposures.
Prior to performing the
modification no formal safety evaluation was performed, nor was
the modification work performed under an approved procedure.
10 CFR 50.59 permits the holder of a license authorizing
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operation of a production or utilization facility to make
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changes to the facility as described in the SAR without prior
NRC approval provided a review is performed to determine that
the changes do not involve an unreviewed safety question.
The
above modification clearly changed the beam port as described in
the SAR, but a safety evaluation was not performed.
The
staff.did make a presentation
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experimenter and reactor facility (RSC) in December 1982, and the
to the Reactor Safety Committee
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Committee approved the experiment based, in part, on its being
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similar to previously approved experiments.
Once the neutron
radiography facility was completed, a memorandum dated February
16, 1983, from the Director of the Reactor Facility to the RSC
describing the modification was provided to the Committee
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pursuant to its earlier request.
The Committee was not
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consulted prior to starting the current modifications to the
radiography facility.
Failure to perform a safety evaluation when changing from the
closed and plug-filled condition (as described in the SAR) to
the open condition (with the absent plugs compensated by water
shield and the blockhouse) was idertified as an apparent
violation of 10 CFR 50.59 (50-62/87-03-01).
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(2) Technical Specification (TS) 6.3 requires that written
procedures revicwed and approved by the Reactor Safety Committee
be in effect for the installation and removal of experiments and
experimental facilities. The installation of the blockhouse and
other equipment necessary to support the beam port operation was
performed in 1983 without a procedure.
Failure to have approved written procedures for the initial
installation of the NRB and modification of the beam saield in
1983 was identified as an apparent violation of TS 6.3
(50-62/87-03-02).
The subsequent operation of the modified facility, including the
closed fill system has been conducted without procedures.
Interviews performed by the inspectors during this inspection,
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indicated that pe sonnel monitoring the level in the clear
plastic hoses on the beam port fill tank did not understand the
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significance of the water level in the hoses.
It was the
understanding of the staff that a water level in the fill tank
line indicates a full beam port... However, a water level in the
hose might indicate only a partially filled beam port at best.
Failure to have approved written procedures for the operation of
the NRB between 1983 and July 2, 1987, was identified as another
example of an apparent violation of TS 6.3 (50-62/87-03-02).
Prior to the 1983 modification of the beam port, the front tube
(shield) of the beam port was drained to atmospheric air
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pressure when the tube was opened for use.
When the tube was
open argon-41 was produced.
When the tube was refilled the
argon-41 was vented to the exhaust system.
To eliminate the
production and release of argon-41, the. front tube was modified
to be a closed system utilizing a demineralized water storage
tank with a helium cover gas and a reversible peristalic pump.
When the front tube is filled, the tank holds a small amount of
excess water and a large volume of helium cover gas.
When the
front tube is drained, the tank is almost filled with water
causing the front tube to be fillea with helium gas.
The licensee noted a problem with water in the helium fill
line around noon on July 2, 1987.
Actions taken by the licensee
to remove the water in the helium fill line were performed
without an evaluation to determine the source of the water.
A
probable source of water was from the beam port, and operation
to remove that water could have also caused additional water to
be removed from the beam port shield.
Subsequently, the licensee attempted to duplicate a situation of
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water in the fill line at the expense of water in the beam port
shield.
The licensee identified no combination of actions that
lead to the removal of water from the beam tube without
operating the pump, regardless of the position of the peristalic
pump on the hose.
The licensee believes that the pump was
operated for up to 30 seconds to remove the water from the.
shield,
Modification of the blockhouse commenced on June 17, 1987,
without a procedure.
The licensee did not prepare a detailed
plan for the blockhouse modification giving sufficient
Nnsiderations to radiation safety hazards.
Supervisory
responsibilities for the modifications were split between two
persons.
The inspector determined that each of the supervisors
had the responsibility for monitoring modification activities-in
separate weeks and that there had not been a turnover briefing
between the two.
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Licensee management did not require backup radiation detection
capabilities during the period when the beam shield monitoring
instrumentation was out of service.
Neither did the licensee
minimize the time period that locked access control would be
lost or beam shield monitoring instrumentation would be out of
service.
Finally, licensee representatives in charge of the
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moditicutions failed to consult with the radiation protection
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staff on' the modifications.
Feilure to have approved written procedures for modification of
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thi neutron radiography facility which began on June 17, 1987,
wcs identified as another example of an apparent violation of
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Technical Specification 6.3 (50-62/87-03-02).
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(3) Reactor Safety Committee
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describes
the
review
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responsibilities of the of the Reactor Safety Committee.
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Item (4) of 6.2.3 requires the RSC to review reportable
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occurrences and the actions taken to identify and correct the
cause of the occurrences.
The inspector attended a RSC meeting
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on July 15, 1987.
The inspector accompanied the RSC during its
inspection of the blockhouse.
All members spent the time and
asked the questions necessary to understand the initial,
intermediate, and final status of blockhouse construction and
radiography operations.
The Committee then met in executive session for about two hours,
following which they asked the inspector in to hear their
decisions and conclusions.
This was followed by a discussion of
the requirements of 10 CFR 50.59 for review of modifications of
the facility and what constituted a modification.
The inspector reviewed the following written presentations to
the RSC prior to the Committee meeting:
Date
Prepared
Subject
July 10
Neutron Radiography Personnel
Exposure
The exit beam port dose at full
power equaled 12 rem /hr with the
tube an estimated 10% drained and
the lead shutter in place.
This
value
was
obtained
by
extrapolation of data from low
power.
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The report noted that Region II
had requested on July 2 that there
be no further operation of the
neutron radiography facility until
investigation was completed.
July 10, 1987
NRC Inspection of Neutron
Radiography Facility of July 6-8,
1987
This report to the committee
summarizes tr.e exit interview held
on July
8.
Five potential
violations were identified at that
time.
July 14, 1987
Temporary Neutron Radiography
Blockhouse Construction Safety
Method
This standing order provides for
more supervision and radiation
surveillance of work activities
during reconstruction of the
blockhouse,
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July 15, 1987
New S0P for UVAR Beam ports
(SOP 6.9)
This procedure received careful
attention from the Committee,
which revised the submission to
requi re
instrumentation
to
automatically scram the reactor
whenever the blockhouse was
entered with the beam port less
than fully flooded.
In addition,
flooding or draining the beam port
will require action by both the
reactor
and
the
authorized
facility operator.
This procedure was available in
final form on July 16, 1987.
However,
the
instrumentation
required by the procedure was not
expected to be installed until the
following week.
July 15, 1987
Procedures for Operation of
Neutron Radiographic Experiments.
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A
draft of Procedures for
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Experimental Neutron Radiography,
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was enclosed with the submission.
It will, henceforth, require
reactor
operator action
to
energize the pump to fill or drain
the beam port.
July 15, 1987
Neutron Beam Port Monitoring
Devices
The requirements for monitoring
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devices were modified to support
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the requirements instituted under
the topic above.
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July 15, 1987
Recent Events Concerning
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Overexposure to Personnel During
Blockhouse Construction
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(4) Facility Operations
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On July 16, 1987, the inspector witnessed part of the radiation
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survey of the reconstructed blockhouse, and a copy of the
completed radiation survey was obtained for review in the
Region.
Also, the information was obtained on the radiation
environment of the blockhouse (See Table 1).
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Table 1
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2 MEGAWATT NEUTRON RADIOGRAPHY BEAM RADIATION LEVELS (From direct or
extrapolation of low power measurements)
Tube
Shutter
Gamma (Rem /hr)
Neutron (Rem /hr)
flooded
shut
0.001
0.001
partially fl'd
shut
1.0#*
7.250#*
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drained
shut
2.4#
50.0#
drained
open
20.0#
160.0#
- Dose rate extrapolated from low power measurements.
- One and one-half feet from shutter.
All other measurements at contact
with the shutter.
The inspector also witnessed one reactor startup to full power.
The reactivity effect of the subsequent draining of the beam
tube was barely discernable to the operator.
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The inspector determined that the following corrective actions
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were completed or in progress to be completed prior to the
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resumption of neutron radiography:
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1.
Excess transparent, ficxible tubing in the helium fill line
was removed to reduce hideout of water.
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2.
Access to the pump, reservoir, and tubing is now controlled
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by a locked door.
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3.
A procedure for conduct of blockhouse modification
activities has been approved and issued.
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4.
A procedure for conduct of neutron radiography activities
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had been approved and personnel will be trained in its use.
5.
The following physical modifications are in progress:
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a.
Operation of the fill and drain . pump will be
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controlled by a series switch in the Control Room.
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b.
A light beam activated switch will cause an automatic
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reactor scram if the beam target area is approached
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with the beam tube drained and the scram breaker
closed.
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c.
The BF3 counter will be reinstalled as a diverse and
redundant monitor of beam port flooding status.
6.
A safety analysis in accordance with 10 CFR 50.59 will be
performed on the existing, modified, neutron radiography
facility.
b.
Radiation Protection
(1) Access Controls
10 CFR 20.201(b) requires that each licensee make or cause to be
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made such surveys as may be necessary for the licensee to comply
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with the regulations and are reasonable under the circumstances
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to evaluate the extent of the radiation hazards that may be
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present.
10 CFR 20,201(a) defines survey as an evaluation of
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the radiation hazards incident to the production, use, release
disposal or presence of radioactive materials or other sources
of radiation under a specific set of conditions.
10 CFR 20.203(c)(1) requires that each high radiation area,
where a person could receive a whole body dose in excess of.
100 mrem / hour be conspicuously posted as a high radiation area.
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10 CFR 20.203(c)(2) requires each entrance or access point to a
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high radiation area to be equipped with a control device to
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reduce the radiation exposure that an individual may receive to
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a dose below 100 millirem in one hour upon entry or equipped
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with a control device which shall energize a conspicuous visible
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or audible alarm signal in such a way to alert an individual
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entering the high radiation area and the licensee or a
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supervisor of the activity are made aware of the entry or be
maintained locked except during periods when access to the area
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is required with positive control over each individual entry.
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Prior to the blockhouse modifications which began June 17, 1987,
the licensee utilized a conspicuous visible alarm signal to
alert persons entering the blockhouse of potential radiation
hazards and administrative controls to meet the requirements of
10 CFR 20.203(c) and control entry into the facility.
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The licensee utilized two sensors to warn persons entering the
neutron radiography blockhouse that the neutron beam port was
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open.
A signal from either the LED sensor indicating the
absence of water in the shield fill tube or the BF3 neutron
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detector indicating the presence of neutrons in the block house
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could cause a sign indicating " beam open" to light.
The " beam
open" light was located just above the blockhouse access door.
There was also an audible alarm that would sound anytime that
the blockhouse door was opened to alert persons in the area that
an entry into the blockhouse was in progress.
Discussions with
the licensee and observations by the inspector indicate that the
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alarm system was not designed such that the licensee or a
supervisor was also made aware that an entry into the facility
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was being made.
The sensors to the " beam open" sign and the
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audible alarm on the access door were disconnected when the
blockhouse modifications began and remained disconnected on
July 2, 1987,
Prior to the blockhouse modifications, the licensee also
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controlled access to the high radiation area by locking the
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access door.
Through interviews with licensee representatives,
the inspector determined that the licensee did not have
procedures for the blockhouse facility that would require tiie
facility health physicist to be notified of blockhouse entries
or activities.
The inspector also determined that the licensee
had approximately five keys assigned to various members of the
facility staff that could unlock the padlock utilized to secure
the blockhouse door.
The inspector also determined through interviews with licensee
representatives that entries into the blockhouse required the
use of calibrated portable survey instruments when the " beam
open" light was on.
Part of the modifications which began on
June 17, 1987, required the relocation of the blockhouse access
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door.
The inspector determined that the blockhouse door was
unlocked from June 17 to July 2,1987, to allow work on the
modifications.
The inspector determined that during this time
period that at least six individuals, members of the staff and
students, entered the block house as needed to perform their
modification tasks.
The inspector determined that during the
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modification period (June 17 to July 2,1987), the licensee did
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not require positive control over each individual entry into the
blockhouse; persons working in the area were not required to
have special monitoring devices such as neutron dosimetry or
portable radiation survey instruments; nor did the licensee
initiate increased surveillance of potential radiation hazards,
additional surveys or special health physics coverage.
During
this period the licensee continued to perform routine weekly
surveys of the area.
When the modifications to the blockhouse began, the licensee
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removed the instrumentation that would warn individuals of the
presence of a high radiation area.
The licensee also removed
the only administrative control to the blockhouse when the door
was unlocked.
On July 2,1987, licensee representatives discovered that the
neutron beam port had inadvertently drained causing the block
house to have neutron and gamma radiation dose rates of up to
12 rem / hour. The discovery was made by an individual working on
a modification in the blockhouse when his alarming dosimeter
alarmed when he entered the NRB.
Failure of the licensee to
make or cause to be made surveys necessary to identify a high
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radiation area in the neutron radiography facility on or before
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July 2, 1987, and to take appropriate action to ensure the area
was properly posted and access to the facility controlled was
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identified as an apparent violation of 10 CFR 20.201(b)
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(50-62/87-03-03).
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The licensee was required by Radiation Control Procedures to
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perform weekly surveys of the nuclear reactor facility.
The
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inspector reviewed the last weekly survey performed in the
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blockhouse prior to July 2,1987.
The survey results, dated
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June 29, 1987, showed up to 60 mrem / hour gamma inside the beam
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port cavity.
Licensee representatives reported that the dose
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rates in front of the beam port inside the blockhouse to be less
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than 2 mrem / hour.
Through discussions with the licensee, the
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inspector determined that on July 2,1987, the blockhouse and
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the beam port cavity had been posted as a radiation area.
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10 CFR 20.401(b) requires a licensee to maintain records showing
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the results of surveys required by 10 CFR 20.201(b).
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10 CFR 20.201(b) requires a licensee to make such surveys as may
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be necessary for the licensee to comply with the regulations of
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Through interviews conducted with licensee representatives, the
inspector determined that on July 2,1987, after the facility
health physicist became aware of the increased radiation levels
in the NRB, he entered the neutron radiography blockhouse with a
portable gamma survey instrument to survey the area.
The
inspector asked to see the July 2,1987, survey results on
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July 7,1987.
A licensee representative acknowledged that the
initial gamma survey made of the neutron beam port on July 2,
had not been documented.
Failure to document a radiation survey
made July 2,1987, in the neutron radiograp)hy(50-62/87-03-04).
blockhouse was
identified as a violation of 10 CFR 20.201(b
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Licensee representatives stated that it was impracticable to
document all surveys performed at the University's Research
Reactor.
The inspector stated that documentation and
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maintenance of survey results is required in accordance with
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Section 20.401 when the surveys are performed to demonstrate
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compliance with the requirements of 10 CFR 20.
The inspector
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stated that if radiation surveys are made for purposes other
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than showing compliance with 10 CFR 20, then the licensee should
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provide guidance for distinguishing between official and
unofficial surveys in approved written procedures.
Licensee
representatives disagreed with the inspector's position that
documentation and maintenance of the survey was required and had
not documented the survey results when the inspector departed
the facility on July 8,1987.
Through discussions with licensee representatives and review of
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instrument calibration records, the inspector determined that
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the BF3 detector utilized in the neutron beam port shield
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monitoring system had never been calibrated. The licensee also
did not perform periodic surveillance on the monitor to ensure
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it was functioning properly.
The licensee stated that the
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monitor was not utilized to assess radiation exposures but was
utilized only as a neutron sensor to determine the presence or
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absence of neutron radiation.
The inspector stated that
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although there is no requirement that the neutron detector be
calibrated, the detector is a part of the high radiation area
access control system for the NRB.
Therefore, it is necessary
for the licensee to ensure, by appropriate periodic surveillance
that the detector is functioning properly.
Surveillance testing
of the neutron detector was not included in any approved
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procedure.
Failure to have an approved written procedure
addressing surveillance testing of the neutron detector was
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identified as another example of an apparent violation of TS 6.3
(50-62/87-03-02).
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The licensee experienced difficulties in determining the
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blockhouse dose rates that were present on July 2,1987.
The
licensee did not have instruments that could measure the neutron
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dose rates directly.
The licensee had one portable survey
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14
instrument capable of measuring up to 5000 mrem / hour neutron
radiation.
To determine the dose rate in the blockhouse room on
July 2, the licensee reduced the reactor power from 100% to 10%
full power and made gamma and neutron surveys.
The licensee
extrapolated the 10% survey results to those expected at 100%
power assuming a linear function.
The calculated maximum
exposure dose rate value was determined by the licensee to be
800 rem / hour.
During the week of July 13, 1987, the licensee
conducted additional radiation surveys to determine neutron to
gamma ratios at low power levels.
The licensee extrapolated the
survey results to 100% power and reported maximum dose rates of .
180 rem / hour in the block house when at full power and the water
shield fully open.
c.
Personnel Exposures for Blockhouse Workers
Through discussions with licensee representatives and a review of
records, the inspector determined that six licensee employees and
students had worked in the neutron radiography blockhouse from
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June 17, to July 2,1987.
The licensee utilizes a vendor supplied
film badge for monitoring gamma and beta radiation, a film with
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cadium filter for thermal neutron monitoring and a polycarbonate
solid state recoil dosimeter for fast neutrons.
The licensee issues dosimetry having neutron beta and gamma
monitoring devices only to those individuals normally working around
neutron radiation areas.
Other licensee employees and students
receive beta and gamma radiation dosimetry.
The licensee determined stay times in the area from interviews with
those persons working in the area on July 1 and 2, 1987.
Based upon
the interview information, the maximum combined time spent by any one
person in the area was determined to be approximately five hours.
The licensee estimated on July 2,1987, that potential exposures as
high as 50 rem were possible.
The estimates were based on the
maximum dose rate in the neutron beam with the reactor at 10% power
extrapolated to 100% power (12 rem / hour).
On July 2,1987, the licensee also gathered gold rings from two of
the blockhouse workers and analyzed them for Gold-198.
The highest
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neutron exposure determined from the measurements and calculations
for gold activation was 13 mrem.
Results of the investigation performed by the licensee indicate that
the beam opened July 1, 1987, and that the beam opening on July 1 was
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considerably less than the opening found on July 2.
The assumption
is based primarily on the exposure received by Worker D.
Worker D
had a gamma dose of 20 mrem and a neutron dose of 140 mrem as
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measured by gamma and neutren film badge all of which was received
during a five hour period on July 1,1987
Worker D did not work in
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the blockhouse on Thursday July 2, 1987. Worker D wore the dosimetry
on the waist in line with the beam.
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Worker A did not have neutron dosimetry, but received a dose of
30 mrem gamma, the highest gamma dose of the blockhouse workers.
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Worker A like Worker D worked on the radiography camera in the path
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of the neutron beam.
Worker A worked approximately 4-6 hours on the
camera on July 1 and about 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> on July 2,1987.
Worker A also
wore the dosimetry on the waist.
The other workers spent
considerably less time in the blockhouse than did Workers A and D.
The licensee had made neutron and gamma surveys to determine the
neutron to gamma ratio of the beam at low power levels and had found
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the ratio to be 8 to 1 neutron to gamma.
The ratio of neutron to
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gamma as measured on Worker D's dosimetry was 7 to 1.
The licensee
assigned the measured doses to those persons having neutron
dosimetry.
All persons working in the blockhouse wore their
dosimetry on their waist which would have placed the dosimeter at the
beam height.
For workers not having neutron dosimetry the licensee
assigned a neutron dose based upon the measured gamma dose utilizing
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the 8 to 1 neutron to gamma exposure ratio.
The highest dose assigned to a worker was 270 mrem.
The inspector
determined that these exposures received by the workers in the
blockhouse while the water shield was partially drained was less than
the limits of 10 CFR 20.101.
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