ML19341D042
| ML19341D042 | |
| Person / Time | |
|---|---|
| Site: | University of Illinois |
| Issue date: | 02/28/1981 |
| From: | ILLINOIS, UNIV. OF, URBANA, IL |
| To: | |
| Shared Package | |
| ML19341D039 | List: |
| References | |
| NUDOCS 8103040755 | |
| Download: ML19341D042 (2) | |
Text
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o ANNUAL REPORT January 1, 1980 - December 31, 1980 ILLINOIS ADVANCED TRIGA Facility License R-115 I.
SUMMARY
OF, OPERATING EXPERIENCE A.
Summary of Usage The reactor was scheduled for usage an average of 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> per week and was in operation an average of 17.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> per week. This usage was almost identical to the previous year.
In the following table, the percent of time for different purposes is given. Scheduled time is that reserved for a given operation, while operating time is that from start-up to shutdown.
Category Operational Scheduled Research Projects 24.0%
22.9%
Sample Irradiation 43.6%
37.6%
Education and Training 29.6%
35.6%
Maintenance and Measurements 2.8%
3.9%
There are two individuals with a Senior Operator License and three with an Operator License. The facility basically operates on a 40-hour week and has two full-time equilavent operators and a reactor health physicist available.
B.
Performance Characterists 1.
Fuel Element Length and Diameter Measurements A set of measurements was made for the D-G hexagonals on January 23-25, 1980, i
while the elements in the B-C hexagonals were checked on March 28, 1980. No i
changes were noted from previous measurements in either case.
The total number of pulses at the end of 1980 was b,365.
Values for pulse height, period, and fuel temperature continue at the same values.
2.
Reactivity Control Rods:
The reactivity worths of the control rods has been essentially stable since 1975. One exception is the fast transient rod which has an increase of about 13% when a new control rod was used to replace a damaged control rod in 1979.
Some variations may occur if measurements are made with a moderate concentration of xenon in the core.
It might be noted that the number of fuel elements in 1975 was 93 compared to the present 100.
Core Reactivity: The loss in reactivity, attributed to burn-up, was
$0.16 for the year. This value is deternined by a comparison of the cold critical rod positions.at the beginning and end of the year. The number of fuel elements 8103040 755
D Page 2 in the core has remained at 100.
Present excess reactivity is about $6.04 ar.d the shutdown margin with the most resetive rod removed is $3.12. -
II.
TABULATION O_F, ENERGY AND PULSING
~A.
Hours Critical and Energy g o_f Operation Time (hrs)
Energy (MW-hrs) f 0-10 kilowatts 307.8 0.0 10-250 kilowatts 133.2 25.1 250 kW - 1.5 megawatts 242.6 194.8 Pulsing 237.6 3.8 TOTAL 921.2 223.7 B.
Pulsed Operation Pulse Si:e Number
$1.40-1.70 2
1.71-2.00 18 2.01-2.30 0
2.31-2.90 26 2.91-3.19 532 3.20-3.55 1
TOTAL PULSES 579 III. REACTOR SCRAMS There were 37 unplanned scrams and no emergency shutdowns. The scrams were attributed to: Operator error - 24, Instrument malfunction - 10, and External causes - 3.
The following is a list of the systems that initiated the scrams.
Linear Recorder - Power Level (14 scrams)
There were 12 operator errors that occurred when the range switch was moved down-range either too soon during a power decrease or in the wrong direction. This is a typical error made by a trainee at the controls. One scram resulted from depressing the UP button when the DN button should have been used and the other was when the peak power from a square wave was underestimated and the recorder went off scale.
Period (13 scrams)
There were 5 operator errors in switching to the automatic mode incorrectly or by withdrawing control rods too far before the period circuit was operational.
The other 8 scrams were from noise in the circuit.
It should be noted that this is not a required scram, but is utilized for training purposes. This scram is 1 frequently by-passed when noise appears in the circuit.
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Page 3 Primary Flow (5 scrams)
This scram occurs if forced convective cooling has not been initiated when the power level reaches 1.0 MW.
The scram results from a combination of the primary flow signal and the power level from the log N circuit. Three of these scrams were operator errors from increasing the power level above 1.0 MW without forced cooling. Two resulted from noise in the log N circuit that tripped the relay.
Percent Power (1 scram)
This scram occurred when the mode switch was moved from the pulse mode to I
the square-wave mode.
The switch had been in the pulse position to check the calibration of ny (peak power from a pulse) and the fuel temperature indication on the linear recorder. Attempts to cause a scram indication by the same sequence of actions were not successful. However, a negative movement of the percent power needle is noted if the change is made immediately after the nv signal is enecked.
Fuel Element Temperature (3 scrams)
Two of these scrams were caused by a RF signal from CB transmitters being used near the laboratory. When the reactor is at high power, the signal is sufficient to cause a fluctuation in the temperature reading to the scram set Point.
The other scram resulted when power to the fuel temperature circuits was turned on after it had been inadvertently removed.
An overshoot of the needle caused the scram.
(See Power Source to Fuel Temperature Circuits, page 4.)
Low Water Level (1 scram)
The initiation of the 3 gpm core spray system can be checked by depressing a float switch at the top of the reactor tank.
Depressing this switch also results in a water level scram.
In this case, the float switch was checked when'the reactor was in operation causing the scram.
IV.
MAINTENANCE Approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> / month was used for maintenance during 1980. This work was done when reactor operation was not scheduled and hence is not included in the summary on Page 1 of this report.
An additional 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> / month are spent on surveillance requirements. Fifty of these hours were included on Page 1 of the report.
The major maintenance that occurred is described below:
Adjustable Transient Rod:
A problem was noted with the position indicator for this rod.
The indicator would oscillate about 100 divisions with the control rod in a set position. The malfunction was traced to a bad capacitor.
This was not considered as an abnormal occurrence since the Technical Specifications only deal with the application or release of air (scram) in the operation of this control rod.
The description and evaluation of this malfunction was reviewed by
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the Nuclear Reactor Committee on May 21, 1980.
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Page 4 Fission Chamber:
Previous to a start-up, from 10 to 10 cps were being obtained from the start-up channel that utili:es a fission chamber. Normal rates are 3-10 cps depending on previous opcrations. After numerous checks on the pre-amplifier, the cable resistance to the chamber was measured and found I-to be well below expected values. From these measurements, it was surmised that the difficulty was from a break-down in the chamber. Since considerable time would be necessary to obtain and install a new chamber, a request was made to the USNRC for permission to use an alternate system with a BF tube. An 3
Amendment was received with the provision that the alternate system could be j
used for a period of 6 months.
This will expire in April,1981.
l 7.
CONDITIONS UNDER SECTION 50.59 of 10, CFR A. Changes to System Exhaust >bnitor: A solid state scaler and rate-meter was designed and installed as a replacement for a tube-type scaler and indicating meter. This system is used to measure the release of gaseous effluents through the building exhaust system. The rate-meter gives a digital read-out of the counts each second and will give an alarm if the rate exceeds a set value.
The scaler integrates the counts and is utili:edto determine the amount of radioactive gases in the exhaust air. This is combined with the flow rate to calculate the values given in Section VI.
The change was made because of numerous maintenance problems with the 20-year old tube-type scaler.
The change was reviewed and approved by the 4
Nuclear Reactor Committee on September 19, 1980.
j Power Source to Fuel Temperature Circuits: This change is contained in a I
letter to the Directors Division of Reactor Licensing on December 5,1980.
The change was made to avoid the possibility of a recurrence of an abnormal condition in which the power to the circuits was lost when a switch on a pilot strip receptacle was turned off.
Power is now taken from the same receptacle that powers the console so that an inadvertent removal of the plug will shutdown the reactor.
The change was reviewed and accepted by the Nuclear Reactor Committee on January 30, 1981.
B.. Changes,to, Procedures Use g E Chamber for Start-up Channel 3
A interim written procedure for the use of the BF tube as a replacement 3
t for the fission chamber was made. The original procedure was included in the request for the Amendment. However, once it was determined that the interlock circuitry could be used, a second procedure was written. The Amendment allows the 4
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Page 5 use of either procedure. The original procedure was approved by the Nuclear Reactor Committee on October 16, 1980 and the second one was approved on November 26, 1980.
Nuclear Reactor Committee Meetings: A sentence in the document,
" Responsibilities, Charges and Composition of the Nuclear Reactor Committee,"
was changed.
The sentence originally stated that, "The Committee shall meet at least quarterly--no more than three months without meeting."
The three months was changed to 115 days because of difficulties that occur with meetings during the summer months.
The 115 days was in line with a recommendation following an bspection when it was noted that almost four months had elapsed between two consecutive meetings.
This time will be a 25% extension fo-the three month designation.
C. Experiments A new experiment, " Temperature Increase in B Coated Al Tubes," was reviewed and approved by the Nuclear Reactor Committee on September 19, 1980.
The experimental set-up was the same as for previous nuclear pumped lasers experiments.
However, the reactor was operated for short periods of time at a high power level rather than the pulsed operation used for the other experiments. The temperature increase in the gas mixture in the Al tube was measured during the operation.
The only additional hazard associated with the experiment was that the dose rate outside of the reactor building might exceed 2 mr/hr. To avoid any infraction
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of 10 CFR 20, the time of each run was limited such that the total dose in any one hour would be less than 2 mr.
In addition the region where the higher dose rates occurred was under direct surveillance during each operation.
It should be noted that there were no individuals in the area during the runs except the observers.
(SECTION VI.
See page 7.)
VII. ENVIRONMENTAL SURVEYS The only environmental surveys that are conducted are those where an above normal dose rate may be expected outside of the reactor building as per the experiment in VI.C.
After these surveys the experiment is conducted in a manner to assure compliance with the requirments of 10 CFR 20 on the total dose to unrestricted areas.
Contamination surveys are made in the laboratory as indicated in a later section.
VIII. PERSONNEL RADIATION EXPOSURE AND SURVEYS WIT 11IN FACILITY A.
Personnel Exposure Sixteen persons were assigned film badges at the facility. Three of these are full-time employees, while the others average less than 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> per week
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Page 6 at the facility. The badges were sent to the Radiation Detection Company in California until March 24, 1980.
From March 24 to July 1, 1980 they were sent to R. S. Landauer Co. in Glenwood, Illinois.
For the remainder of the year, results were obtained from Searle Health Physics Service in Des Plaines, Illinois.
In addition to the badge, a dosimeter is also worn if an above normal radiation exposure is likely to occur. The table below gives the dose received by those assigned film badges:
Dose (Rems)
Number of, Individuals No measurable exposure 3
0.01 -- 0.10 12 i
0.10 -- 0.25 0
0.25 -- 0.50 1
Total = 16, The highest individual dose was~395 millirems. This was received by the Reactor Heslth Physicist who handles the radioisotopes that are produced, conducts i
smear tests on Campus sealed sources, and performs calibrations for radiation monitoring instruments. Individual doses to students and visitors from 1
dosimeter readings were less than 10 millirem.
B.
Contamination Surveys Smear samples from 34 locations in the laboratory are taken at periodic j
intervals. The removable beta contamination is determined by checking.the samples with a flow counter.
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The maximum concentration is in the vicinity of the tubes from which irradisted samples are removed. During the year, there were 3,762 samples I
irradiated.
In the' sample area, the contamination varied from 12 to 17,800 dpm/100 cm or 0.5 x 10~7 to 8.0 x 10-5 uCi/cm.
After measuring the larger 2
value, the area was cleaned and this reduced the maximum rate to 1.5 x 10-6 uCi/cm,
2 2
Smears from other areas in the laboratory showed a maximum of 279 dpm/100 cm 4
-6 or 1.3 x 10 uCi/cm.
. Samples in the control room and lobby are all less j
than 1 x 10"7 uCi/cm'.
IX. NUCLEAR REACTOR COMMITTEE The present committee is composed of 4 members of the Nuclear Engineering 2
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Staff, 2 members from the Health Physics Staff, 'and the Reactor Supervisor.
Dr. Lou Milavickas replaced Dr. Arthur B. Chilton as the Chairman.
Dr. Milavickas has been on the committee for several years.
Dr. James F. Stubbins replaced Dr. Chilton as a member of the committee.
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1 Page 7 VI. RELEASE OF RADIOACTIVE MATERIAI.S The average concentration of A-41 released to the environs via the
-8 building exhaust system was 4.5 x 10 uC1/cc. The total release for the year was 1.35 Curies with a range of 40-278 mci per month. These values are related to the energy produced and the length of time for an operation.
It is estimated that about 1 mci of tritium is released during the year from the evaporation of water in the reactor tank.
This is based on the concentration of tritium in the water and the estimated loss as indicated by the number of gallons of water added during the year.
The gross beta activity in the water effluent to the sanitary sewer from the laboratory retention tank was zero release.
During the past year there was no water pumped from the retention tank to the sewer.
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