ML20099G904
| ML20099G904 | |
| Person / Time | |
|---|---|
| Site: | University of Iowa |
| Issue date: | 06/30/1992 |
| From: | IOWA STATE UNIV., AMES, IA |
| To: | |
| Shared Package | |
| ML20099G898 | List: |
| References | |
| NUDOCS 9208180012 | |
| Download: ML20099G904 (4) | |
Text
.. - - - _ _ - -. . - . - . - _ - - . - - _ _ - . . . -_
r .
ANNUAL OPERATIONS REPORT for the Docket No. 50116 July 1,1991 - June 30,1992 !
3 This is a routine o,.antions report to the Nuclear Regulatory Commission in accordance with the requirements of Section 6.6 of the Tech tical Specifications,
- Appendix A to Operating License R-59.
- 1. . Summary of reactor operating exoerience including the enerev produced by
.the teactor:
.The reactor is operated in support of undergraduate and graduate teaching laboratories and graduate student research in the nuclear engineering program. - Two courses viere given during the spring semester which provided hands on laboratory experience for students in the undergraduate and graduate nuclear engineering programs. T The use of the reactor was limited to experiments that could be performed as part of the requin.d start up testing program for the low enriched uranium core (LEU) or at power levels less than critical.
During the period July 1,1991 - 3 me 30,1992, a total of 0.06 kilowatt hours of energy production andIL4.honIs of operation were recorded. last year's numbers were 227 kilowatt-hours and 222 hours0.00257 days <br />0.0617 hours <br />3.670635e-4 weeks <br />8.4471e-5 months <br />. The HEU core accumulated a total of 7324 kilowatt-hours oj energy production and a total of 8674 hours0.1 days <br />2.409 hours <br />0.0143 weeks <br />0.0033 months <br /> of operation from initial criticality in 1959 to its removal in May of 199L Since the initial criticality of the LEU core in August of 1991, the cumulative operations hours are 214 and the cumulative kilowatt-hours are 0.06 kWh. The total energy produced during the facility's lifetime (both HEU and LEU cores) is 7324.06 kWh with a cumulative ' operation time of 8888 hours0.103 days <br />2.469 hours <br />0.0147 weeks <br />0.00338 months <br />. A percentage breakdown by operations categories for the years 90-91 and 9192 is shown below.
9208180012 920G10 DR -ADOCK 05000116 PDR
- _ _ a ~ .z_.-.. - . - , - . - . . - . - . .-
_ _ _ _ _ __ _ _ _ _._ _ _ _ _ _ _ _ _ .--. _ ._ _ _ _ .m. _ .
m l
Table 1. Allocation of energy production and operations time, in percent.
Research Teaching Maintenance Operator Service Grad U Gr..: Training Energy (%)
90-91 47.0 0.1 44.5 8.3 0.1 0.0 91-92 0.0 0.0 0.0 86.1 13.9 0.0 Time (%)
90-91 17.7 10.8 29,1 29.1 13.1 0.0 91 92 0.0 4.1 1.9 89.1 4.9 0.0 The large share of time allocated to maintenance this past year is due to SRO l supervision of refueling the reactor and assembly of all the low enrichment uranium j (LEU) fuel elements in July 1991 and the startup testing required with the new core. !
Initial criticality of LEU core was achieved on 8/14/91. l
- 2. Unscheduled shutdowns including. where argjicable. corrective action taken to I preclude recurrence: ;
There was one unscheduled shutdown during the reporting period.
One automatic shutdown occurred on 8/21/91 when reactor power was raised to one watt with the start up source still fully inserted in the core. The shutdown occurred while performing rod worth measurements and was attributed to operator error.
Addition. personnel were provided to assist with rod worth measurements which minimized future distractions to the reactor operator. The reactor.was secured and later restarted without incident.
- 3. Ma_ior preventive and corrective maintenance operations.having safety significance >
On 8/1/91 the first LEU fuel was asscmbled and inserted 'in the wre. Fuel was '
added in increments in accordance with the approach to critical procedure until a critical mass was achieved on 8/14/91.
During the fuel load, u darker than expected discoloration was noticed on the
- alumim;m fuel cladding. On 9/w/91 reactor operations were terminated until the cause of the discoloration was determined. Babcock and Wilcox (B&W), the fuel's manufacturer,-was notified. Scanning ele on microscope and Uray diffraction analysis identified the cause of the disccioration compound called bayerite, a form of aluminum' hydroxide. A detailed water analysis of the primary coolant was pertarmed by
f the university's Analytical Services Lab. All parameters analyzed were found to be normal. The entire volume of primary coolant was replaced with deionized water and the ion exchanger resin was changed out. Additional cladding surveillances have been implemented to monitor the fuel cladding and reactor operation was resumed on 12/18/91.
During an inspection of the fuel cladding by B&W a crack was noticed in the roll pin of the removed element. This prompted an inspection of each element's roll pin.
All roll pins were found with visually obvious cracks. The NRC was informed. Testing demonstrated that the roll pins cracked within 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> of submersion in watei when pressed into the fuel element's lifting cone. The tests were performed in primary coolant delonized water, and tap water. All roll pins tested cracked. When the roll pins ,
were inserted in water without being pressed into the lifting cone no cracks occurred. A replacement pin made from 303 stainless steel was proposed. The proposed roll pin was fabricated and tested. A procedure for replacement was written and approved. LEU roll pir. aplacement was completed on 12/13/91.
- The primary coolant flow transmitter failed and was replaced with a new ,
functionally equivalent flow transmitter. The flow indicator / controller was also replaced.
The flow calibiation procedure was re-written reflecting the differences between new and old equiiment.
l The process instrumentation power supply failed and was replaced with a functionally equivalent power supply.
These projects were reviewed and approved by the Reactor Use Committee. In cases where potential radiological hazards could exist, health physics personnel performed the necessary surveys, monitored areas and personnel, and gave approval for working in all radiation environments.
- 4. Major changes in the reactor facility and procedures. and new tests or fxperiments. or both. that are significantly different from those performed
,psylously and are not described in the Safety Analysis Report. including conclusions that no unreviewed safety questions were involved:
There were two major changes made at the facility during the reporting period.
Low enriched uranium fuel was added to the reactor. - A new piocedure was written for the approach to criticid and the initial criticality. This procedure was reviewed and approved by the Reactor Use Committee. The Committee concluded that no unreviewed safety. questions existed.
Also during this reporting period, cracks were found in the LEU fuel element's roll pins.
A special procedure was written for the removal of the fuel from the core and the replacement of the roll pin. The procedure was reviewed by Babcock & Wilcox and reviewed and approved by the Reactor Use Committee. The Committee concluded that no unreviewed safety questions existed.
l i'
- 5. Summary of the natur,q and amount of radioactive effluents released or I
discharged to the environs beyond the effective control of the University as l dettrmined at or before the point of such release or discharge. (included. to the extent practical. are estimates of individual radionuclides present in tigeffluent if the estimated averace release after dilution or diffusion is less than 25 oercent i
of the concentration aIlowed or recommended. a statement to this effect is usedh l
, Argon 41: The technical specification limits on release of this radionuclide to .
the environs are based on weekly (up to 100 kWh) and annual (up to 4760 kWh) energy i production of the reactor. The operating records show that less than 25% of the l concentration allowed was released to the environs.
Others: No measurable amounts of other radioactive efnuents were released to the environs.
- 6. Summarized results of any environmental surveys peiformed outside the facility:
No environmental surveys outside the facility were required to be performed since
- the trigger level, based on surveys inside the facility, was not exceeded.
- 7. Summarv of exposures received by facility persontiel and visitors where such sxoosures are greater than 25 oercent of that allowetl or recommendeth l
No facility personnel or visitors had exposures greater than 25 percent of that allowed or recommended.
)
l I'
l l
- . - . - . .- . - - . ._ . - - - - _ - - - . _ .