ML20046A389

Annual Operating Rept for IA State Univs UTR-10 Reactor, for 930701-0630.W/930720 Ltr

ML20046A389
Person / Time
Site:	University of Iowa
Issue date:	06/30/1993
From:	Adams J IOWA STATE UNIV., AMES, IA
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9307280030
Download: ML20046A389 (5)

Text

y+ y- 3 IOWA STATE UNIVERSITY  %%fn'"$""1"*icat Engineering O F S C 11i N C E A N D T E C 11 N O L O G Y 2a25 11. M. Black Engineering Building Ames, Iowa 500:1 2160

$15 2941423 FAX 515 294 326 Docket No. 50-116 Ref: 10 CFR 50.71'(a)

July 20,1993 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington , DC 20555

Dear Sir:

Enclosed with this letter is the Annual Operations Report for the Iowa State University UTR-10 reactor. The period covered by this report is from July 1,1992 to June 30,1993.

Sincerely, b-, $ h mrzb John T. Adams Reactor Manager Enclosure cc: American Nuclemr Insurers D. B. Bullen, Facility Director R. A. Jacobson, Chm., Radiation Safety Committee T. II. Okiishi, Chm., Mechanical Engineering Department ,

E. E. Sobottka, Dir., Environmental IIealth and Safety Department T. L. Zimmerman, Chm., Reactor Use Committee U. S. NRC, Region 111 2600.a3

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Annual Operations Report '

Iowa State University's UTR-10 Reactor -;

Docket No. 50-116 July 1,1992 to June 30,1993 This is a routine operations report to the Nuclear Regulatory Commission in accordance with the requirements of Section 6.6 of the Technical Specifications, Appendix A to Operating License R-59.

1. Summary of reactor operatine exoerience includine the enerev produced by the reactor:

The reactor is operated in support of undergraduate and graduate teaching laboratories and graduate student research in the nuclear engineering program. Two laboratory courses were taught during this reporting period which provided hands on laboratory experience for students in the graduate nuclear program. The reactor was also used to _ support undergraduate students who are working towards an undergraduate degree in Engineering Operations with the Nuclear Operations' option.

During the period July 1,1992 to June 30,1993, a total of154.31 kw-hrs ofenergy production and 173.13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> of operation were recorded. Last year's numbers were 0.06 kw-brs and 214 hours0.00248 days <br />0.0594 hours <br />3.53836e-4 weeks <br />8.1427e-5 months <br />. The HEU core accumulated 7324 kw-hrs ofenergy 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 -

1991. Since the initial criticality of the LEU core in . August of 1991, the cumulative ,3 kilowatt-hours are 154.37 kw-hrs and the cumulative hours of operation are 387.13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />.

The total energy produced during the life of the facility ( both HEU and LEU cores) is

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7478.37 kw-hrs with a cumulative operation time of 9061.13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />. A percentage >

breakdown by operational categories for the yea:r 91-92 and 92-93 are shown below.

Table 1. Allocation of energy production and operation time, in percent.

Year Research Teaching Teaching Maintenance Operator Senice  :

Undergrad. Graduate Training Energy %

9l-92 0.0 0.0 0.0 86.I 13.9 0.0 92-93 92.7 <0.1 <0.1 3.0 4.3 0.0 Time %

91 0.0 1.9 4.I 89.I 4.9 0.0 4 92-93 '20.6 0.9 16.0 23.6 38.9 0.0 C

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2. Unscheduled shutdowns includine, where applienble, corrective action taken to preclude recurrence:

There were no unscheduled shutdowns during this reporting period.

3. Maior preventive and corrective maintenance operations having safety significance:

On September 16,1992 precritical checks were aborted due to the failure of the " percent power" trip on the right hand wide range channel. The problem was traced to the reset switch. A new switch was drawn from spares and installed. The " percent power" trip on the right hand wide range channel was tested and found to operate properly. "

On October 29,1992 the switch which controls the power to the reactor control console was depressed in preparation for a reactor startur. The switch failed to provide power to the console. Investigation revealed that the switch had failed. A new switch was ordered, installed, and tested.

On November 13,1992 while performing a normal reactor shutdown, the shim-safety -

control rod stuck in a position 33% out of the core. The shim safety rod inserted 'on its own approximately 20 minutes following the shutdown. The NRC was notified that day of the event. On November 16,1992 a representative from NRC, Region III arrived onsite to assess the event. Special procedures were required to gain entry to the core because insufficient space existed in the fuel storage pits to accommodate all the fuel in the core.

Procedures were developed, reviewed, and approved which allowed entry into the core region without the removal of all fuel. On December 1,1992 personnel entered the core and inspected all components associated with the shim-safety control rod. The cause for the failure was traced to the inner pillow block bearing. It was noticed while rotating the inner pillow block bearing that an increase in resistance existed which corresponded to the 30% out position of the control rod. A new bearing was ordered and installed. Ce'1 trol rod response times were measured and found to be satisfactory.

A review of the operational history of the UTR-10 safety type control rods conducted by the Reactor Manager and the NRC Inspector revealed two other occurrences of safety type control rod failure during the life of the facility. With this information, it was decided to replace the inner pillow block bearing on all the safety type control rods. The replacement of these bearings has been scheduled for July of 1993.

A need for a long term solution to the bearing problem was also indicated by the multiple failures of these bearings over the life of the facility. An analysis of the time between failures was conducted. The results of the analysis showed that the minimum time between -

observed bearing failures was 8 years. With this information, the reactor staffis writing 'a -

new procedure which will require the replacement of the inner pillow block bearings on a

9 5 year interval. This procedure is expected to be completed and approved no later than July of 1993.

On June 14,1993 while performing the Core Outlet Temperature Calibration Procedure, improper operation of the process instmmentation test switch was observed. Investigation revealed that two of the 5 sections of the switch had failed. A supplier for a new switch was located and a new functionally equivalent switch was ordered. The replacement switch will be installed as soon as it arrives. Expected arrival is late July or early August.

Temporary connection were made on a spare section of the switch to allow for the testing of Reactor High Level Scram function.

Throughout the reporting period, monitoring of the incore cladding samples has continued. Two of the three samples in the core have continued to darken. The remaining -

sample has evenly darkened and does not appear to be changing. Also, fission product analysis using the high purity germanium detector (HPGe) continued on a weekly basis until May 12,1993 when the analysis frequency was changed by the Reactor Use Committee. Now, analyses are performed after each critical operation of the reactor. The cause of the darkening has still not been determined, but Gerard Hofman, a senior metallurgist from Argonne National Lab (East), has provided and continues to provide assistance in determining and correcting the cause. A sample of the cladding samples in the -

core will be provided to Dr. .Hofman in July for further analysis.

4. Maior channes in the reactor facility, procedures, and new tests or en,criments, or both, that are significantly difTerent from those performed previously and are not described in the Safety Analysis Report, including conclusions that no unreviewed safety ouestions were involved:

There were no major changes in facility, procedures, tests, or experiments.

5. Summary of the nr.ture and amount of radioactive emuents released or dischareed to the environs beyond the effective control of the University as determined at or before the point of such release or discharge. (Included, to the extent practical, are estimates ofindividual radionuclides present in the emuent. If the estimate averaec release after dilution or diffusion is less than 25 percent of the concentration allowed or recommended, a statement to this elTect is usedh  ;

Argon-41: The technical specification limits on release of this radionuclide to the environs l are based on weekly (up to 100 kWh) and annual (up to 4760 kWh) energy production of l the reactor. The operating records show that less than 25% of the concentration allowed )

was released to the environs.

Others: No measurable amounts of other radioactive efiluents were released to the environs.

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6. Summar. 2 results of any environmental surveys performed 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. Summary of exposure received by facility personnel and visitors where such exposures are greater than 25 percent of that allowed or recommended:

No facility personnel or visitors had exposures greater than 25% of that allowed or recommended.

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