Part 2

This condition would result from a mechanical failure in the primary loop pumps, piping, etc., or by accidentally stopping the pumps when the reactor is at power, or by loss of power to the pumps. When a single pump fails to operate for any reason, an alarm is sounded to warn the operator. If all four pumps fail to operate for any reason, a signal is sent to the reactor safety system to “scram” the reactor.

LOSS OF POWER TO SAFETY CIRCUITS

The hydraulic drives that operate the “scram” mechanism require reserve pressure to keep them in the “ready” position for “scram” condition and are an integral part of the safety circuitry. A power failure in the safety circuits would automatically put the hydraulic drives into operation to “scram” the reactor.

LOSS OF POWER TO CONTROL ROD DRIVES

Each of the 21 control rods has its own drive mounted vertically on the upper reactor head. Of these, 9 are servo controlled and 12 are of the nonservo type. The 9 servo rods have variable speed drives and operate in two groups in a synchronous manner, according to demand signals from the reactor system. The 12-rod group can be operated manually or in groups according to predetermined conditions. All of these operate at a speed determined by their gearing.

The safety considerations are as follows:

1. Each servo loop contains a monitor that will sound an alarm and initiate a fast insertion if the rod fails to follow its command signal.

2. Another circuit monitors all nine servo monitors, and should any of the servo monitors malfunction, an alarm will sound and appropriate corrective action will be taken through the automatic safety system.

3. “Scram” action starts in the safety system and is independent of operator control. Once started, a “scram” action cannot be stopped.

4. For conditions that do not warrant “scram” action, a fast insertion serves to reduce power and permit the operator to correct the condition without a complete shutdown. A manual fast insertion can be made by the operator.

The electrical circuits controlling the reactor control rods are monitored, and an electrical failure in one or more circuits will result in a fast insertion or “scram” action. Should electrical power to the control rod drives fail completely, the hydraulic drives will be actuated.

WASTE STORAGE AND HANDLING

This system drains and collects, until safe for removal, all drainage from the reactor system that might be radioactive. Drainage may result from a leak, or be part of the normal drainage accumulation during initial fill and testing, normal startup, operation and shutdown, and decontamination.

The drainage and storage system consists of two pumps, valves, piping, containment drain tank, and four waste storage tanks. The total capacity of the tanks is 1,350 cubic feet. This is approximately 80 percent more than the maximum operational leakage and drainage for a 100-day period. Provisions are made to take samples from any of the five tanks at any time.

After sampling indicates sufficiently low level of activity, the fluid will be pumped to special dock facilities for transfer to inland waste disposal sites. No waste will be discharged at sea under present operating plans.

A special 129-foot vessel, the NSV ATOMIC SERVANT, will service the Savannah’s reactor and handle the radioactive wastes.

The majority of the potentially radioactive gases vent into a central manifold. Here they are monitored, diluted by fan-driven air and discharged up the radio mast after passing through a series of filters. During normal operation, the manifold is vented continuously. However, if the radiation monitor indicates activity levels too high for satisfactory dilution, the gases can be diverted into the containment shell.

GAS FILTERED, MONITORED

The region between the containment vessel and the secondary shielding is ventilated with a 4,000 cfm fan which discharges about half way up the radio mast. This gas is not expected to be radioactive but as an added precaution it is monitored to determine if radioactivity is present.

All gases released through the radio mast are filtered to remove particulate matter.

The containment shell air is purged with fresh air periodically at sea and prior to entry by the ship’s engineering crew. During normal operation the only radioactive gas in the shell is argon-41, at a concentration less than the maximum permissible level for continuous occupational exposure. The only potential sources of activity in the containment air above tolerance levels would be fission products and these are not present during normal operation. However, as previously described, prior to purging, air samples will be analyzed to ascertain the activity levels.

HEALTH PHYSICS MONITORING SYSTEM

This system provides radiation protection to crew and passengers through constant monitoring for any abnormalities in radiation levels that might occur. This is accomplished through a system of 12 radiation detector units in the following locations: A-deck, outside doctor’s office; B-deck, aft passageway; B-deck, port passageway; C-deck, port passageway; C-deck, aft passageway; D-deck, starboard passageway; D-deck, both fore and aft bulkheads and at tanktop level, the port, starboard, fore and aft passageways.

These 12 monitor units feed their readings into 2 channels, with 6 monitors on each channel according to a predetermined sequence. A manually operated detector permits switching to any one monitor to allow observation and study of that station for as long as desired. By means of a recorder on each channel, a permanent record of the 12 monitoring stations can be obtained.

The detectors are calibrated and maintained periodically by operating personnel using a standardized cobalt-60 source.

Ionization chambers located at the points of entry into the containment vessel will determine when it is safe to enter the vessel. In addition, anyone entering the vessel will carry a portable monitor to determine the dose rate at the point he will be working.

In addition to the installed detectors, there is a full complement of portable equipment to make any specific investigations required. The equipment is used to check decontamination results and to monitor contaminated spaces during maintenance. Health physics personnel, equipped with portable equipment, accompany all groups working any area that might contain radioactivity.

The health physics laboratory aboard the ship is outfitted for all tests required during the operation of the reactor plant.

AUXILIARY SYSTEMS

_Sampling System._ This system provides a means for removing liquid samples from the primary loop to determine the effectiveness of the purification system. Samples will be taken from both the inlet and outlet flow of the primary demineralizers.

_Intermediate Cooling System._ The primary function is to provide clean cooling water to the various reactor system components. A secondary function is to maintain water in the annular primary shield tank.

The system consists of two separate flow circuits: a sea water circuit and a fresh water circuit. Each of these circuits contains two pumps and two coolers, plus other necessary components. The pumps and coolers are arranged in parallel, permitting either pump to supply water to either cooler.

In the sea water circuit, inlet temperature is 85° F and outlet temperature is 106° F. The fresh water enters its coolers at 143° F and leaves at 95° F.

Components outside and inside of the containment vessel are cooled by one or the other of these intermediate cooling circuits.

EXTRA EMERGENCY POWER

Two auxiliary 750-kw diesel generator sets are on standby to provide the following: (1) Power to the main bus for operating those loads needed to supply cooling for decay-heat removal after a scram or shutdown, (2) emergency “take-home” power should the nuclear power plant become inoperative, (3) power for reactor startup, and (4) spare generating capacity for normal operation should a turbine generator become inoperative.

In the event of a reactor “scram,” these generators will automatically start and synchronize on the main bus bar to supply and distribute power to the components used for reactor cooling.

A 300-kw emergency diesel generator is also available to supply power to the 450-volt emergency switchboard. This source will operate in case both the main turbine generators and auxiliary diesel generators do not. Loads connected to the emergency switchboard include lighting, low speed windings of the primary coolant pumps, and the emergency cooling system.

A battery protected source will also provide power to those loads that require an especially dependable power source with no interruption due to loss or switching of auxiliary power.

TAKE-HOME POWER

As mentioned, in the electrical system there are two 750-kw diesel generator sets installed in the engine room. If any emergency “take-home” power is required, either diesel generator can be used to operate a 750-hp wound rotor motor, which is connected to the ship’s propeller, through the reduction gears.

Each diesel generator is sized to furnish adequate power for reactor decay heat removal, lighting, and necessary ship service.

N.S. SAVANNAH MANNED FOR SAFETY

To assure that the first nuclear-propelled merchant ship will be completely safe, it is manned by well-trained, competent personnel whose duty and responsibility it is to operate the ship safely and efficiently.

Every mechanical and electrical safety device of modern navigation is at the disposal of the SAVANNAH’s crew to insure the safety and integrity of the ship.

The men who will handle the SAVANNAH ashore and afloat will have had the advantage of the specialized and extensive training program conducted by the Atomic Energy Commission, the Maritime Administration, and the private contractors who built the N.S. SAVANNAH and her reactor.

The ship’s master and officers are men of long experience on the sea whose backgrounds assure sound and stable assessment and judgment under all possible conditions.

All of the factors herein discussed make it possible for the United States Government to say of the N.S. SAVANNAH, as she ushers in the atomic age on the world’s essential trade routes, that this unique and wonderful vessel is unquestionably one of the world’s safest ships.

THE NUCLEAR SHIP SAVANNAH IS DESIGNED AND BUILT TO THESE SAFETY REQUIREMENTS

_APPLICABLE CODES OF_:

1. U.S. Coast Guard 2. American Bureau of Shipping 3. Maritime Administration 4. U.S. Public Health Service 5. American Institute of Electrical Engineers Marine Code 6. U.S. Atomic Energy Commission

_SAFETY REVIEW BY_:

1. AEC Advisory Committee on Reactor Safeguards

_DESIGN REVIEW BY_:

1. U.S. Coast Guard 2. Maritime Administration 3. AEC (A) Oak Ridge National Laboratory (B) Electric Boat Company 4. American Bureau of Shipping

U.S. GOVERNMENT PRINTING OFFICE: 1960 O—562017

PASSENGER DINING ROOM CREW QUARTERS MAIN LOUNGE PASSENGER STATEROOMS REACTOR HATCH REACTOR AUX. HATCH CREW QUARTERS CARGO HOLD MACHINERY CONTROL CENTER ENGINE ROOM SHIP’S PROVISIONS STABILIZER SPACE CARGO HOLD REACTOR CONTAINMENT VESSEL

Transcriber’s Notes

—Silently corrected a few typos.

—Retained publication information from the printed edition: this eBook is public-domain in the country of publication.

—In the text versions only, text in italics is delimited by _underscores_.