ML19294B752
| ML19294B752 | |
| Person / Time | |
|---|---|
| Site: | University of Illinois |
| Issue date: | 02/29/1980 |
| From: | ILLINOIS, UNIV. OF, URBANA, IL |
| To: | |
| Shared Package | |
| ML19294B751 | List: |
| References | |
| NUDOCS 8003050466 | |
| Download: ML19294B752 (6) | |
Text
.
ANNUAL REPORT January 1, 1979 - December 31, 1979 ILLINOIS ADVANCED TRIGA Facility License R-115 I.
SUMMARY
OF OPEPATING 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 17.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> per week.
The total usage was about the same as the previous year. However, the reactor was operated for a 5.5 month period with only one transient control rod which limited the si:e of pulses. A check shows that the scheduled and operating times for this period were 19 and 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> per week.
During the other 6.5 months, these values were 28 and 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> per week.
In the following table, the percent of time used for different purposes is given. Scheduled time is that reserved for a given operation, while operating time is that from start-up to shutdown.
Cate go ry Operational Scheduled Research Projects 24.6%
23.0%
Sample Irradiation 45.1%
36.5%
Education and Training 27.6%
33.8%
Maintenance and Measurements 2.7%
6.7%
There are two individuals with a Senior Operator License and four with an Operator License. The facility basically operates on a 40-hour week and has two full-time equivalent operators and a reactor health physicists available.
B.
Performance Characteristics 1.
Fuel Element Length and Diameter Measurements One set of measurements on the elements in the B and C-hexagonals was made during the year.
There were no changes noted in either parameter.
The total number of pulses at the end of 1979 was 5,765.
There has been essentially no change in the pulse height, period, or fuel temperature since the start of operations.
2.
Reactivity Control Rods:
hhen the fast transient control rod was removed for a replacement, two fuci elements were removed from the core region to assure an adequate shutdown margin.
Reactivity measurements gave a decrease of about 10*= for the regulating rod with the other control rods approximately 8 00305 0 i* N[
Page 2 the same reactivity worth. After a new transient control rod was installed and the core returned to normal, an increase of 13% was measured for the new control rod.
However, the extimated reactivity worth of the two transient rods is presently about $4.40 which is less than the maximum pulse of $4.60 tnat is allowed in the Technical Specifications.
Core Reactivity:
The loss in reactivity, attributed to burn-up, was $0.19 for the year.
This value is determined by a comparison of cold critical rod positions at the beginning and end of the year. The number of fuel elements in the core remained at 100 after the new transient control rod was installed. Present excess reactivity is about $6.28 and.he shutdown margin with the most reactive rod removed in $3.11.
II.
TABULATION OF_ ENERGY AND PULSING A. Hours Critical and Energy Type oJ[ Operation Time (hrs)
Energy (MW-hrs) 0-10 kilowatts 304.0 0.0 10-250 kilowatts 90.8 17.1 250 kW - 1.5 megawatts 358.3 302.7 Pulsing 125.5 2.0 TOTALS 878.6 321.8 B. Pulsed Operation Pulse Size Number
$1.00-1.40 2
1.41-1.70 3
1.71-2.00 71 2.01-2.30 1
2.31-2.90 7
2.91-3.19 248 3.20-3.55 1
TOTAL PULSES 333 III.
REACTOR SCRAMS There were 41 unplanned scrams and no emergency shutdowns.
The scrams were attributed to: Operator error - 29, Instrument malfunction - 9, and External causes - 3.
The following is a list of the systems that initiated the scrams.
Linear Recorder - Power Level (20 scrams)
There were 18 operator errors that occurred when the range switch is moved down-range either too soon during a power decrease or in the wrong
Page 3 direction. This a typical error made by trainees at the controls. One scram was due to a bi-stable malfunction and one from a line voltage transient.
Period (15 scrams)
There were 9 operator errors in switching to the automatic mode incorrectly or by withdrawing control rods too far before the period circuit was operational. The other 6 scrams were from noise in the circuit.
It could be noted that this is not a required scram, but is utilized for training purposes.
Primary Flow (2 scrams)
One of these was an operator error in increasing the power level too high (above 1 MW) during natural convective cooling.
One result from placing the log N to calibrate which simulated an operation above 1 MW.
Loss of Power (1 scram)
This came with a momentary loss of power during a thunderstorm.
Percent Power - Power Level (1 scram)
This was an operator error in which a control rod was raised instead of being lowered during an operation at 1.5 FM when xenon was being burned-out of the core.
Fuel Element Temperature (2 scrams)
This scram is 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 of the temperature reading to the scram set point.
IV.
MAINTENANCE Approximately 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> / month were used for maintenance.
This work is typically done when reactor operation is not scheduled and this part is not included in the summary on Page 1 of the Report.
Shintenance.that interfered witn normal operation totaled 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> during the year. This was primarily due to tne removal and later installation of the fast transient control rod and the biennial inspection of the control rods.
It is estimated at 16 hou 3/ month are spent on surveillance requirements. Of these, about 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> / month was included on page 1 of the Report.
Bi-Stable Circuits Several bi-stable circuits were used in the electronics to initiate and reset interlocks, scrams, and the movement of tne fission chamber. Problems were encountered in the drifting of the set points. Since replacements for the original circuits could not be obtained, a new bi-stable.was designed as a replacement.
After installation of this bi-stable in one of the circuits,
Page 4 checkswere made on any drifting of the set points.
It was found to be far more stable than the previous circuit and a second one was installed in one of the other circuits. A review of the change was made to the Nuclear Reactor Committee.
The change was approved on September 5, 1979.
Secondary Pumn Leakage again occurred at tne seals of the secondary pump of the. forced cooling system (Annual Report - 1978).
When the seals were removed, it was found that the inner sleeve was loose.
This was re-scaled and the spring tension on this sleeve was reduced. This was completed on May 1, 1979 and no leakage has been noted since that time.
Fast Transient Control Rod A welded connection just above the poison section of the fast transient rod broke loose on March 20, 1979. Checks were made to assure an adequate shutdown margin with the remaining control rods for the physical removal of tnis rod.
Data obtained showed that this specifications would be met.
- However, on the following day during a calibration of one of the control rods, it was noted that the shutdown margin was less than the limit in Technical Specifications.
An abnormal occurrence report was prepared and sent to the Division of Reactor Licensing (Date of Report - March 22, 1979).
This report describes the malfunction of the fast transient rod system.
To avoid questions concerning Quality Control, a decision was made to order a replacement for the lower portion rather than attempt to reclad the control rod in a machine shop.
The new rod was received in the last part of August and installed on September 6,1979.
V.
CONDITIONS UNDER SECTION 50.59 of 10 CFR 20 A. Changes to,Syster There were no changes to the system.
The 'bi-stable, reviewed in the section on maintenance, was considered to be the replacement of a part with one having b'etter characteristics.
B. Changes to, Procedures (1) The Reactor Start-up and,0peration Written Procedures were change in requiring the operator to make a periodic check on the excess reactivity and shutdown margin. This was approved by the ' Nuclear Reactor Committee.
(2) A Special Written Procedure for the movement of fuel elements after the shutdown margin was found to be inadequate following the removal-of the fast transient control rod was prepared, iThe procedure was reviewed by the Nuclear Reactor Committee and the final report of the data was ac nted.
Page 5 C. Experiments The only new experiment was a change in a previous experiment oft nuclear pumped lasers. This change consisted of new mirrors and the use of different gases in the cell.
Calculations made for the possible release of Ar and Xe showed that they would be 2 orders of magnitude below the limit given in the Technical Specifications or in 10 CFR 20.
After an evaluation, the experimental change was approved by the Nuclear Reactor Committee.
VI.
RELEASE OF_ RADI0 ACTIVE MATERIALS The average concentration of A-41 released to the environs via the
-8 building exhaust system was 5.0 x 10 uCi/cc. The total release for the year was 1.9 curies with a range of 15-930 mci per month. These values are related to the energy produced and the length of time for an operation.
For the 19 mci month, the total energy was 7.4 SM-hrs and the 930 mci month totaled 106.1 MW-hrs.
It is estimated that about 1 mci of tritium is released during a year from the evaporation of water in the reactor tank.
The gross beta activity in the water effluent to the sanitary sewer from the laboratory retention tank was 6.2 microcuries.
VII. ENVIRON > ENTAL SURVEYS There were no environmental surveys taken during the reporting period.
Contamination surveys are made in the laboratory as indicated in a later section.
VIII. PERSONNEL RADIATION EXPOSURE AND SURVEYS WITHIN FACILITY Twenty persons were as' signed film badges at the facilityI 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 at the facility.
The badges were sent to the Radiation Detection Ccrpany in California where. dosages less than 10 millirem are not reported.
In addition to the badge, a dosimeter is worn by an individual if an above normal radiation exposure is likely to occur. The table below gives the dose received by these assigned film badges:
Dose (Rems)
Number of Individuals No measurable e:posure 2
0.01 -- 0.10 15 0.10 -- 0.25 3
Total = 20 When not in use, the badges are placed in a rack in the control room.
During a research experiment, the dose in this area was about 1 mr/hr for a period of 25-30 nours.
Thus the badges received this exposure including a control room badge.
It is estimated that 6 individuals would have been in the
l Page 6 No measurable exposure category rather than tne one indicated.
The highest individual dose was 250 millirems.
This was received by one of the Reactor Health Physicists who handles the radioisotopes that are produced, does smear tests on Campus sealed sources, and performs calibrations for radiation monitoring instruments.
Individual doses to students and visitors, from dosimeter readings, was less than 10 millirens.
Contamination, Surveys Smear samples from 34 locations in the laboratory are taken at periodic intervals. The removable beta contamination is determined by checking the samples with a flow counter.
The maximum concentration is in the vicinity of the tubes from which samples are removed after an irradiation in the reactor. During the year there were 3,054 samples irradiated.
In the sample area, the contamination varied from 23 to 12,200 dpm/100 cm or 1.0 x 10' to 5.5 x 10' uCi/cm.
After the larger number, the area was cleaned which reduced the maximum
-6 rate to 2.3 x 10 uCi/cm. Smears from other areas of the laboratory showed
-7 a maximum of 129 dpm/100 cm or 5.8 x 10 uCi/cm'.
IX.
NUCLEAR REACTOR C05NITTEE The present committee is compose of 4 members of the Nuclear Engineering Staff, 2 members from the Health Physics Staff, and the Reactor Supervisor.
There were no changes in membership during the year and Dr. Arthur B. Chilton continued as Chairman.
k