SUNDAY BRIEFING : An occasional...

Inside the Nuclear Reactor

The heart of San Onofre is its nuclear reactor. It can produce vast amounts of energy from a small amount of fuel. How it’s done: 1. Uranium atoms split (fission) inside fuel rods; occurs trillions of times per second, creating heat. 2. Water circulating inside reactor core is heated to more than 600 degrees Fahrenheit. 3. Hot water passes through pipes into boiler and is converted to steam. Remaining water is pumped back to reactor to be reheated; cycle repeats. 4. Steam spins a turbine, which drives an electric generator. 5. Ocean water, pumped in from a separate pipeline, cools steam and turns it back into water. Ocean water is returned to sea. 6. Cooled water from condensed steam pumped back into boiler for reuse.

* Not drawn to scale; only a portion of reactor is shown.

How High-Level Radioactive Waste Is Stored

Nuclear fission results in low- and high-level radioactive waste. Low-level waste (worker clothing and tools, etc.) is shipped to licensed disposal sites in Nevada and Washington. High-level waste is stored at San Onofre. *Pools: Steel-lined concrete structures 45 feet deep High-level waste: Clusters of used fuel rods stacked in pools by machine Water: Fuel rods submerged into pools with at least 23 feet covering them; water cools used fuel rods, acts as protective shield for workers

Multiple Safeguards

Uranium, the fuel used to produce nuclear energy, is naturally radioactive. San Onofre uses several physical barriers to prevent escape of radioactive materials. *Fuel pellets: 1/3-inch-diameter uranium pellets lock in radioactive by-products after fission Fuel rods: 12-foot stainless steel or metal tubes encase uranium pellets Reactor vessel: Fuel rods placed in 8-inch-thick carbon steel vessel Steel containment: Vessel enclosed by leak-proof steel-plate shell Containment structure: Airtight, 4 1/2-foot-thick reinforced-concrete walls and 11-foot-thick concrete floor, houses reactor vessel and all equipment in direct contact with it

Plant Particulars * Ownership: Primarily Southern California Edison and San Diego Gas & Electric; cities of Anaheim and Riverside own less than 5% of Units 2 and 3 * On line: Unit 1 began producing power Jan. 1, 1968. and shut down Nov. 30, 1992; Units 2 and 3 began operating in August, 1983, and April, 1984, respectively. * Construction cost: Unit 1: $88 million. Units 2 and 3: $4.5 billion total * Current status: Units 2 and 3 operating with a capacity to serve 2.75 million households * Employees: 2,500-3,000 * Employee requirements: Security screening and psychological profiles, physical exams every two years; operators receive additional training and licensing by Nuclear Regulatory Commission. * Annual payroll: $120 million * Annual expenditures: $250 million, including property taxes, salaries and operating and maintenance expenses

Edison’s Energy Mix

In 10 years, nuclear power has gone from being Edison’s least-used energy resource to being the third-largest. A Edison’s sources:

1983 Other utilities: 40% Gas: 33 Coal: 15 Hydro: 10 Non-utility energy: 1 Nuclear: 1

1993 Non-utility energy: 34% Gas: 23 Nuclear: 18 Coal: 13 Hydro: 7 Other utilities: 5

2003 Nonutility energy: 31% Gas: 24 Nuclear: 16 Other utilities: 13 Coal: 11 Hydro: 5

Price Comparisons Average cost of different energy sources per kilowatt hour in 1993: Source: Cost Oil: 7.996 Gas: 2.930 Coal: 1.226 Nuclear: 0.537

San Onofre’s Future

The California Public Utilities Commission’s Division of Ratepayer Advocates has recommended that San Onofre be shut by 1998, 15 years ahead of schedule, on the grounds that it is too expensive to operate. Two public hearings before an administrative law judge were held in June. Judge will submit a report to the PUC, which is expected to decide the question later this year. * Opponents: Say it would be cheaper to shut San Onofre and use alternate energy sources like solar power and natural gas. (Proponents say San Onofre is cost-effective and will save its ratepayers at least $1 billion if allowed to operate through 2013.) * Proponents: Believe plant infuses $250 million in annual revenue into surrounding communities and closure would further deflate an already sagging economy. (Opponents say the nuclear power industry is dead in this country and producing electricity through renewable resources will increase the number of local jobs tenfold.)

Thumbs Up, Thumbs Down Advantages of nuclear power have long been weighed against health, safety and environmental concerns. Some pros and cons of nuclear energy:

(Graphic: Pro) * Economics: One pound of nuclear fuel releases as much energy as does combustion of three million pounds of coal.

(Graphic: Con) * By-products: Uranium produces radiation long after its use as a fuel for nuclear energy. Safe way to store uranium waste permanently has not been perfected.

Nuclear Report Card Throughout each year, the Nuclear Regulatory Commission evaluates plant operations at San Onofre and other nuclear plants. The evaluation rates the plant on a scale of 1 to 3--with 1 being best--in several categories, including plant operations and maintenance. In the past five reports, San Onofre has consistently rated above average. *1987-88: 1.71 1988-90: 1.43 1990-91: 1.57 1991-92: 1.43 1992-94: 1.50

Average Radiation Doses Exposure to radiation is a fact of everyday life. Most Americans receive about 300 millirem per year. A millirem is a small unit of radiation. It would take a dose of 50,000 millirem in one day to produce flu-like symptoms. Some common radiation exposures: *Source: Millirem Chest X-ray: 10 per X-ray Dental X-ray: 130 per full set High-voltage color TV*: 0.03 per year Wrist watch: 0.03 per year Smoke detector: 0.03 per year Airplane trip from Los Angeles to London: 4 per round trip * Depending on age of set, distance from viewer

Power Load

The percentage of time San Onofre’s two reactors are operating at full capacity has increased dramatically. Levels are higher if mandated shutdowns for maintenance and the like are discounted: *Unit 2

8/88-7/90: 75.5% 7/90-3/92: 73.6% 3/92-12/93: 85.4% 12/93-present: 99.5%

Unit 3

8/88-7/90: 81.2% 7/90-3/92: 85.2% 3/92-12/93: 81.4% 12/93-present: 97.3%

If the Sirens Sound If an emergency occurs at San Onofre, long, steady sirens will sound for three to five minutes. If you hear an alert: * Keep calm: Sirens sound in time to react cautiously. * Tune in: Listen to local radio or TV station for news and instructions. * Neighbor check: Make sure neighbors heard the sirens and know what to do. * Avoid calls: Do not use the telephone unless absolutely necessary. Emergency workers need lines. Do not dial 911 except to report an immediate life-threatening emergency. * Indoor shelter: If advised to stay inside, close all doors and windows and shut off all systems that draw outside air into building. Keep pets inside if possible. * Evacuation: If advised to evacuate, leave the area promptly after turning off lights, appliances and water, locking windows and doors, and taking enough necessary personal items to last several days. Close all vents and windows in vehicle and do not use air-conditioner. * Family: Do not attempt to pick up or call children or family at schools, hospitals and the like. Public facilities follow their own emergency procedures.

Glossary Background radiation: Radiation occuring naturally in the environment through light, heat and radio waves. Chain reaction: Continuous, self-sustaining series of fission reactions in a mass of uranium. Fission: To split or break an atom into two new atoms or fragments. Releases energy and produces heat used to boil water and make steam in steam generator. Half-life: Time required for half the atoms of a radioactive substance to decay into another substance. Kilowatt: A unit of power equal to 1,000 watts. Megawatt: A unit of power equal to 1 million watts. Nuclear radiation: High-energy particles and rays given off during a nuclear reaction. Nuclear reactor: Device producing nuclear energy by means of controlled chain reactions. Radiation: Form of energy that moves in waves or particles. *Sources: Southern California Edison, San Onofre Nuclear Generating Station, World Book Encyclopedia, “The Way Things Work,” by David Macaulay; Researched by CAROLINE LEMKE / Los Angeles Times