1946-07-31 Decontamination Procedures on Target Vessel – DIRECTOR OF SHIP MATERIAL JOINT TASK FORCE ONE

Navy Reports that document the dumping of nuclear waste directly into San Francisco Bay as well as other Navy Bases, the orders, correspondence, etc.

[Note all page numbers and notes will be enclosed in these brackets]

Citation: https://archive.org/download/DTIC_AD0473908/DTIC_AD0473908.pdf


31 July 1946.


To: All Target Vessels.

Subj: Decontamination Procedures on Target Vessels.

  1. Most target vessels are contaminated to a greater or less degree with fission products and therefore present varying degrees of radiological hazards which at the present time prevent reboarding. Decontamination procedures are being carried out at the present time in order to make it possible for portions of the crews of these vessels to return aboard to complete the decontamination procedures. It is expected to bring the radiological hazards now existing in general on the topside of these vessels to a point where it will be possible for personnel to be aboard for a period of at least four (4) hours at one time. Commanding Officers should therefore, organize boarding parties on this basis and in consideration of the conditions and procedures contained in this memorandum.
  2. Fission products are sub-microscopic particles and therefore not visible to the eye and their presence can only be determined, by the use of monitoring instruments. These products are extremely difficult to remove in as much as they are quite firmly imbedded in the paintwork, metallic structures, wooden decks and particularly in such absorbent materials as lines, clothing, bunting, etc. Great care must also be taken in all decontamination procedures to prevent personnel engaged in these operations from becoming contaminated themselves.
  3. The following procedures will assist in re-establishing normal conditions. It is expected that procedures will have to be repeated a number of times in order to get effective results.

(a) Washing down entire ships including topside structures, decks, sides and ail exposed gear. It has not been possible up to the

Enclosure (B) to Enclosure (F) to Director Ship Material Serial 00447
Page 4
[Page 5]

present time to determine how much contamination exists below decks and these conditions must be determined as soon as boarding parties arrive.

(b) In order to carry out (a) above it will be necessary to gain access to certain below decks spaces to establish power, either by installed generators, ship’s boilers, or by portable pumps available for this purpose. Access to the necessary spaces must be monitored carefully. It is hoped that because of the steps taken to close all openings below decks that below deck spaces will be relatively free of radiological hazards. However, attention is invited to the fact that hazards existing on one side of a deck or bulkhead also presents a hazard on the other side. For instance, it is quite certain that hulls of ships below the water line generally will be highly radioactive at this time and therefore it is desirable for all personnel to keep at a distance of at least two (2) feet from these portions of the hull except for short periods necessary to do essential work such as opening and closing valves, etc.

(c) The object of (a) above is to remove as much as possible of the less firmly attached fission products. Subsequently, it will be necessary to follow more drastic procedures in order to remove the remaining products; generally speaking, it will be necessary to remove by polishing, vigorous scrubbing, holystoning, or other means, at least a portion of all surfaces and carefully washing down all removed material and insure that it is washed overboard. At the present time, the Director of Ship Material is conducting experiments with foamite lye, flour slurries, and other absorbent materials in the hope that some material available on the ships can be used to hasten the processes of decontamination. Damage to paint and appearance by using these methods are of no consequence.

  1. The following precautions should be taken by ail personnel in these operations in order to prevent possible exposure to radiological hazards.

(a) Monitors must be present at all times during these operations.

(b) Do not remain on the ship beyond the tolerance hours set.

Enclosure (E) to Enclosure (F) to Director Ship Material Serial 00447


Page 5
[Page 6]

(c) All personnel to be fully clothed at all times and to have a complete change of clothing and effective showers after each operation in which they are engaged. In this connection it is desirable to wear rubbers or boots and acid-resistant gauntlet type rubber gloves as these materials can be cleaned more easily. For instance, the fission products attach themselves more readily to leather, leather shoes, and leather gloves and are most difficult to remove even by laundering. All clothing worn must be laundered after each operation. All contaminated clothing should, wherever possible, be carefully washed out separate and apart from the ship’s regular laundry. For small amounts buckets and tubs can be utilized. Where the lots are so large as to make use of the ship’s regular laundry facilities mandatory, the inside of the equipment should afterwards be thoroughly scrubbed with an abrasive soap, such as Bon-Ami.

(d) During any hosing or washing down operations, personnel should be to windward of all such operations in order to prevent spraying and wetting themselves and any other personnel on board. Great care must be exercised in this respect, particularly until the ship begins to reach normal conditions.

(e) Upper vertical surfaces will present the greatest difficulties in decontamination and work on these surfaces must be controlled so as to prevent any spray or drippings falling on other personnel.

(f) Access passages to the most used and most necessary spaces in the ship should be decontaminated as soon as possible, in other words, set up definite routes of access which must be used by all personnel until general clearance is obtained.

(g) Determine as soon as practicable what space below decks are free from contamination or relatively free from contamination and require personnel to remain in these spaces at such times as they are resting or eating.

(h) It will be necessary to use K-rations at least in the beginning and these should be brough daily rather than in large supplies, and a space free from contamination used for keeping them until meal hour. Fresh water in canteens must be brought each day and handled in the same way.

(i) Determine as soon as practicable the condition of consumable supplies which may have been left on board and also condition of stored fresh water. Samples of suspected or definitely contaminated materials should be brought to the U. S. S. HAVEN properly tagged

Enclosure (B) to Enclosure (F) to Director Ship Material Serial 00447


Page 6
[Page 7]

and identified for further examination. It is desirable that the fresh water from all storage tanks be so tested before using.

(j) All radiological dangers, when found, shall be marked clearly and if necessary roped off to keep personnel at a safe distance.

  1. It is expected that the decontamination procedures on all ships will be rather slow and certainly laborious. Only by careful attention to the above instructions can effective results be obtained in the least amount of time. The Director of Ship Material group and the Radiological Safety Section will cooperate so as to insure that no personnel are subjected to any over-exposure or other hazards. Monitors will be used until the entire ship has been decontaminated, inspected, and declared to be within safe tolerance limits for all personnel to reboard on a twenty-four (24) hour basis.
  2. The above instructions have been approved by the Radiological Safety Section.


CTG 1.2
CTU 1.2.7
Colonel Warren

Enclosure (B) to Enclosure (F) to Director Ship Material Serial 00447


Page 7



Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s