ML19340E203

Semiannual Operating Rept 28,Jul-Dec 1979.

ML19340E203
Person / Time
Site:	National Bureau of Standards Reactor
Issue date:	04/08/1980
From:	Rozier Carter NATIONAL INSTITUTE OF STANDARDS & TECHNOLOGY (FORMERL
To:
Shared Package
ML19340E197	List: ML19340E196 ML19340E203
References
NUDOCS 8101060633
Download: ML19340E203 (8)

Text

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O' National Bureau of Standards Reactor Docket #50-184

! Facility License No. TR-5 OPERATIONS REPORT i - - - #28 - - -

f July, 1979 - December, 1979 4 This report contains a summary of activities connected with the operations of the NBSR. It is submitted in fulfillment of section 7.8d of the NBSR Technical Specifications and covers the period from July 1,1979 to December 31, 1979.

Se,ction numbers in this report (such as, 7.8d(l)) correspond to those used in the Technical Specifications.

April 8, 1980 l

$ d. hW R( BERT S. CARTER Chief, Reactor Radiation Division-l l 1 l

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$L01066f33

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TABLE OF CONTENTS 7.8d(1) Summary of Plant Operations 7.8d(2) Unscheduled Shutdowns

, 7.8d(3)~ Tabulation of Major Items of Plant Maintenance 7.8d(4) Tabulation of Major Changes in the Facility and Procedures, and the Test and Experiments, (10CFR 50.59) i 7.8d(5) Sumnary of Radioactive Material Released and Results of Environ-

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mental Surveys Performed j

7.8d(6) Summary of Significant Exposures Received by facility Personnel and Visitors I

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4 7.8d(l) Summary of Plant Operations During the six month period July 1,1979 through December 31, 1979 the reactor was critical for a total of i

466.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> with an energy output cf 4303.6 MWH.

The reactor was shutdown on August 8,1980 to invesitgate the cause of the hesitation noted in the movement of Shim Arm no. 1 over a range of a few degrees. Subsequent rod drop and speed tests were normal. Initial details were previously

+ submitted in a letter dated August 15, 1979. The entire Shim

Arm assembly, including the drive, was carefully and thoroughly inspected. The problem was isolated to the Shim Arm blade which appeared to be swollen. Visual inspection with a periscope showed rub marks on the blade indicating the blade was rubbing against the side of the central thimble. Also the shadow of the straight thimble cast on the blade appeared to be curved indicating the blade could be swollen. The rubbing was further confirmed by itstening with a sonic device at the i top of the thimble while the blade was manually moved.

- The core was removed to the storage pool and preparations l

were made to remove all of the Shim Arm assemblies. This included design and construction of a special shield cask, I

. special platform and tools for disassembly in the pool under l

water and procurement of needed replacement parts.

The removal and subsequent reinsertion followed carefully prepared procedures. _ Shim Arms no. 2, 3 and 4 were removed l and transferred to the pool at the end of November 1979. Shim

no. 1 was then pulled out and transferred to the storage pool on December 3, 1979. Some force was needed for the swollen i

i blade because it had to pass through a narrow opening in the i

inner reserve tank. The removal was accompliched with only a few scratches on the blade and no damage whatever to

the inner reserve tank. Examination of the removed blades showed no.1 blade to be swollen about an inch in the middle, the other three blades appeared to be normal. It is suspected that a few drops of water may have gotten inside the blade through a flaw in one of the plug welds thereby causing the swelling. .

l All four Shim Arms were reassembled with new blades, new bearings and arbors and returned to the reactor on February 8, and 9, 1980, after which all four shafts with new seals were l engaged. The entire operation went very smoothly. All four Shim Arm drives were then installed and were tested repeatedly over a period of time. In one instance the spring retainer l assembly in the external drive mechanism, made up of two

. cylinders, one moving inside the other, was found to be rubbing when the Shim did not fall from 12*. The outer cylinder, l

l which showed some galling, was replaced and the inner cylinder l

was polished.

l The Shim Arms were thoroughly tested, first they were moved carefully manually, the movement was smooth and free, 1

then traces and times were obtained as they were driven out l

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. and in, and finally drop times were measured. All results again showed smooth and free operation. The core was reloaded in progra=med steps on February 22-24, 1980. Neutron multiplication was monitored following each step. The reactor was critical at low power on February 24, 1980. This was followed by by calibration of the four Shim Arms and Regulating Rod.

, After several days of operation at low and medium power, the reactor was taken to full power on February 28, 1980.

The entire operation of repimeing the Shim Arms was extremely smooth and was accomplished with little or no difficulty.

The return of the plant to nomal was equally smooth, i Because the original problem with Shim Arm no. I was identified by recording traces of the Shim Arm as it is being driven in and out, this procedure will be followed periodically in the future for the new Shims. The old Shims have given I

excellent service for more than 12 years and were scheduled i to be replaced in 1980 or 1981.

i l Even though not required, most surveillance tests that could be performed were continued during the shutdown period.

l The shutdown lasted about six months, most of which was spent l in preparation, and procurement and fabrication of parts and equipment.

The shutdown period was used to perform certain improvements l and maintenance. Prominent among these were:

I I 1. The fuel transfer telescopic cylinder was completely overhauled with new seals, "0" rings, wipers and bearings.

2. Primary piping inside the CO 2-bellows in the subpile _ room was inspected and was found clean and free of corrosion.

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3. Secondary piping in the vicinity of the pumps was stream-lined to bypass the boosters which were no longer in use, thereby provide for straight smooth operation.

4. The two-inch primary drain lines were rerouted and replaced by new certified pipes and welded joints. Both testing and operation of the new lines were satisfactory.

NOTE: Portions of this report extend into the next reporting period, they are included here for completeness.

. 7.8d(2) Unscheduled Shutdowns 7-23-79: Reactor scram during reactor startup when the scram level selector push button was pushed in preparation for switching from 13 percent to 130 percent. This was caused by dirty contacts in the switch.

Restarted after cleaning the switch contacts.

7.8d(3) Tabulation of Ibjor Items of Plant Maintenance

1. Drained and cleaned Cooling Tower basin.

2. Replaced Cooling Tower drain valve.

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3. Repaired North Cooling Tower basin bypass limitorque.

4, Replaced outboard bearing on #3 Secondary main motor.

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5. Installed new ball-nut / lead-screw and cap bearings on #1 Shim Arm drive. ,

I i 6. Installed new spring, shaf t and flappers in 2" check valve (DWV-211).

7. Replaced #1 Experimental D2 0 cooling pump -(canning leak in i

old pump).

8. Installed new inflatable seal on south personnel door.

9. Replaced diaphram in DWV-184.

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10. Installed new seals, 0-rings, wipers and bearings in Fuel Transfer telescoping cylinder,

11. All scheduled preventative maintenance for period completed.

12. Instrument Procedures performed:

FRC-3 Outer Plenum Flow FRC-4 inner Plenum Flow 4 FIA-40 Reactor Outlet Flow LRC-1 Reactor Level LIA-40 Reactor Level NC-1 & 2 Source Range (LCR)

NC-3 Intermediate Pange (Log N)

NC-6 Power Range PC-3 Normal Exhaust System Pressure PC-27 Process Room Pressure SPC-150 Emergency Fan Controller SPS-151 Emergency Standby Fan Controller

13. Replaced compensated ion chamber in Channel NC-3.

7.8d(4) Tabulation of Major Changes in the Facility and Procedures, j

• and the Test and Experiments, (10 CFR 50.59).

• . Removed unused Secondary booster pumps and rerouted Secondary piping. This change allowed for smoother, more direct operation of the Secondary System and has no effect on the operation of the Primary System or the reactor. There were no unreviewed safety questions involved.

7.8d(5) Summary of Radioactive Material Released and Results of

! Environmental Surveys Perfomed.

Ninety-three (93) curies of tritium and 31 curies of Argon-41 were released as gaseous waste, while 603 milli-curies of tritium and 132 microcuries of other'8 y hemitters 1

were released into the sanitary sewer.

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Environmental samples of streams, wells, vegetation and/or soil, and air showed no "significant changes.

7.8d(6) Summary of Significant Exposures Received by Facility Personnel and Visitors

1. No significant exposures were received by cny visitors.

2. One of the facility personnel received a significant exposure of 719 mrem for this period.

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