%DONRleak071255; ]> July 12, 1955 letter from F.W. Gilbert to Dr. Clifford Beck, with enclosure Machine readable transcription Gilbert, F. W. Creation of machine-readable version: James M. Jackson Sanborn Creation of digital images: James M. Jackson Sanborn Conversion to TEI.2-conformant markup: James M. Jackson Sanborn ca. 15 kilobytes NCSU Libraries Raleigh, NC DONRleak071255

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Images of the document pages have been included. July 12, 1955 letter from F.W. Gilbert to Dr. Clifford Beck, with enclosure F. W. Gilbert

4 pp. Manuscript copy consulted UA 105.1

Nuclear Reactor

Prepared for the North Carolina State University Science and Technology Electronic Text Center

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Library of Congress Subject Headings July 12, 1955 English LCSH manuscript 24-bit color: 400 dpi July 12, 1955 letter from F.W. Gilbert to Dr. Clifford Beck, with enclosure

Copy Cable address "MOTA" In your reply please quote file no.

ATOMIC ENERGY OF CANADA LIMITED

CHALK RIVER PROJECT - CHALK RIVER, ONT. Industrial Operation - July 12, 1955

Dr. Clifford Beck North Carolina State College Raleigh, N.C.

Dear Dr. Beck;

Attached you will find my comments on the recent trip to see your reactor. I would like to state that I had a very enjoyable trip. It was a pleasure to work with you and your associates.

Yours very truly, F. W. Gilbert Manager Reactor Operations FWG:ed attch.

REPORT ON TRIP TO OBSERVE THE REMOVAL OF THE REACTING VESSEL FROM THE NORTH CAROLINA STATE PILE.

The North Carolina State University Nuclear reactor is of the water boiler type and consists of reacting vessel of 14 litre capacity containing about 13 litres of uranium sulphate solution. It is water cooled through four cooling coils. Connected to the reacting vessel is a recombination system consisting of an entrainment trap, two catalyst beds, a condenser and a positive displacement gas pump.

On May 6th the reactor operated satisfactorily. However, on May 9th it was found that it no longer had a negative pressure although normally the pressure was maintained at 10" w.g. below atmospheric. It was later found to have a leak in the reacting vessel and also possibly one in one of the water cooling coils. The leakage from the reacting vessel was contained in an outer aluminum envelope. It was decided to replace the reacting vessel and the recombination system. On my arrival on July 6th, the following conditions existed:

The main portion of the uranium sulphate had been removed and stored. The reacting vessel and the envelope had been flushed. An air purge had passed through the reacting vessel and the recombination unit for about six weeks. The shielding blocks were removed from the top of the reactor. The covering plate in the plenum chamber immediately above the reactor had been removed. The control rod lifting mechanism was removed. The shim rods had also been removed. Preparations were going forward for the removal of the reactor vessel itself.

Questions brought out the information that the total power that had been developed by the reactor was about 60,000 kw. hours. About 40,000 of this had been generated in the last six months of operation. This meant that in the total volume of the solution there had been about 2.5 grams of fission products. The subsequent draining and washing of the vessels should have reduced this to less than 1%. The remaining activity was probably trace fission products plated on to the surfaces plus the stainless steel induced activity.

Indications from instrument reading were that the activity was relatively soft. The maximum activity in the plenum chamber was about 60 mr, most of which was coming from the catalyst beds. It would have been possible to shield this from the working space in the plenum chamber but a suitable sheet of lead was not available. It was obvious that consider- able care had been taken in dismantling to this stage as there was no spread of measurable contamination. The preparations that had been made for the shipment of the vessel to Oak Ridge were as follows:

A drum had been lined with a ceramic tile and concrete. The tile had an inside diameter large enough to take the vessel plus a sheet of plastic. There was about six inches of concrete around the tile. This appeared somewhat low but as the drum was to be shipped by truck it was thought that suitable care could be exercised to make the shipment safe. The subsequent removal of the reacting vessel was very well planned and executed. Air contamination was about 50% above background. On removal the activity from the vessel was 1 r, 36% from the centre. In the shipping drum it was 3 r on contact.

Later the recombination unit was removed. The last operation that I saw was the cutting out and removal of the catalyst beds. This was done without incident.

My comments on the operations are as follows: 1. The steps that were taken were well planned and executed in view of the activity that was present.

2. Had the activity been higher it was doubtful whether the control would have been sufficient.

3. Although there is no criticism whatsoever of the operation to date, I feel that to obtain maximum efficiency and at the same time safe operation from this reactor, a full- time supervisor should be employed. This person would then have the time to study thoroughly all operating problems including contamination control.

4. A good chemist, versed in the problems of the reactor operation, whould be available for consultation purposes. For example, I believe that there was probably trace quantities of nitric acid formed which could probably be found in the solution. Although the nitrate would not be serious it could promote pit corrosion.

5. It is suggested that consideration be given to the use of a paladium aluminum catalyst instead of the platinum alumina. Dr. H.S. Taylor of Princeton has design a very efficient material for combining hydrogen and oxygen. It appears to be much less affected by moisture than the platinum catalyst. Also regardless of material the catalyst should be checked in the laboratory before it is used.

FWG:ed