The purpose of DOE’s stockpile surveillance program is to ensure, primarily through three types of tests, that the safety and reliability of nuclear weapons are maintained. Flight tests involve the actual dropping or launching of a weapon, which has had the nuclear components removed. Nonnuclear systems laboratory tests involve testing a weapon’s nonnuclear systems to detect defects due to handling, aging, manufacturing, or design. The nuclear and nonnuclear components laboratory tests involve destructive analysis to identify defects or failures in individual weapon components. Weapons are randomly selected for flight and nonnuclear systems laboratory tests from the stockpile each year. Weapons chosen for the nuclear and nonnuclear components laboratory tests are judgmentally selected from the weapons that have been selected for the other two tests. For testing purposes, DOE considers the active stockpile to consist of nine weapon types—three bombs and six missile warheads, each with unique capabilities. From 1958 to 1996, DOE’s stockpile surveillance program has tested about 14,000 weapons, with about 2,400 findings documented. Over 50 percent of these findings were considered “significant.” A significant finding is the identification of a defect or failure in a weapon system. A defect is an observable anomaly, while a failure is a flaw or malfunction in the weapon that would prevent the weapon from operating as intended. When a significant finding is disclosed, DOE may perform additional tests to confirm the finding, determine the cause of the problem, assess its impact on the stockpile, and recommend a corrective plan. Of the 2,400 findings, 370 were “actionable.” DOE defines an actionable finding as a finding that lowers the weapon’s reliability or for which some action is taken. About 1 in 3 actionable findings (118 findings) have resulted in retrofits and major design changes. The remainder required either process changes or no physical changes. When a weapon’s reliability is lowered because of a finding, the result is reported to the Department of Defense (DOD). DOE and the national nuclear laboratories have determined that they generally need to test about 40 to 44 weapons of each type in the stockpile over a 4-year period. According to DOE officials, over that 4-year time frame, the tests should consist of 8 to 12 flight tests per weapon type (an average of 2 or 3 tests per year) and 28 to 36 laboratory tests of nonnuclear systems (an average of 7 to 9 per year). Finally, from the weapons scheduled for testing each year, DOE designates components from certain weapons for laboratory tests. DOE considers five components to be key—the pit, the secondary, the detonator sets, the gas transfer system, and the high explosives. On average, for each weapon type, DOE believes that one pit, one secondary, two to five detonator sets, one or two gas transfer systems, and one high-explosive system should be tested each year. According to DOE officials, when a significant number of tests are cancelled or delayed, the Department lacks information on the reliability of the weapon. While lack of testing will not affect the reliability level assigned to a weapon (only a test finding can alter the reliability level), the lack of test information reduces DOE’s confidence in the assessed reliability of the weapon. DOE is currently behind schedule in conducting some flight tests, nonnuclear systems laboratory tests, and nuclear and nonnuclear components laboratory tests. For some tests, DOE is several years behind schedule. These schedule slippages are the result of a variety of factors, including an unapproved safety study, suspension of testing at some facilities, and the transfer of testing functions to new facilities. Flight tests involve the actual dropping or launching of a weapon from which the nuclear components have been removed. DOE uses specially designed equipment—referred to as telemetry packages—to test the integration and functioning of the weapon’s electrical and mechanical subsystems. Until November 1992, DOE planned to conduct a minimum of 3 flight tests per year—or 12 flight tests over a 4-year period—for bombs, InterContinental Ballistic Missiles, and Submarine-Launched Ballistic Missiles. According to DOE officials, in November 1992, DOE reduced its plan for testing Air Force InterContinental Ballistic Missiles from three tests per year to two—or eight tests over a 4-year period. DOE officials informed us that they made the reduction based on an evaluation of applicable existing test data and in preparation for the Air Force’s implementation of the START I and START II treaties. Under these treaties, the Air Force will have to reduce the number of warheads carried on missiles. The plan for testing bombs and Submarine-Launched Ballistic Missiles was not altered and remains at 3 per year, or 12 over a 4-year period. DOE officials told us that they believe the reduction in flight tests from three to two per year for InterContinental Ballistic Missiles represents an acceptable increase in the risk of having undetected problems in weapons. The officials explained that by flight testing three weapons per year, there is a 90-percent chance of discovering a “flight-unique” defect if the defect occurs in 18 percent of the weapons. By testing only two weapons per year, the risk increases. With two tests per year, the defect would have to occur in 22 percent of the weapons to have a 90-percent chance of discovering it. DOE officials believe that conducting fewer than two tests per year (or eight tests over a 4-year period) is a concern and a significantly increased risk to the program. Three weapon types—the W62, W78, and W88 warheads—have had, on average, fewer than two tests conducted per year over the past 4 years. Table 1 shows the three weapon types, DOE’s plan for testing, and the number of tests conducted over the past 4 years (fiscal years 1992 through 1995). The W62, a warhead used by the Air Force on the Minuteman III missile, has been flight-tested six times (of the eight planned) over the past 4 years. Two planned tests were not conducted because DOE’s Pantex facility had trouble preparing warheads for flight testing and could not deliver the test warheads to the Air Force in time for the test flights. The W78 warhead, also used on the Minuteman III, has had seven flight tests (of the eight planned) over the past 4 years. DOE and the national laboratory officials told us that a flight test with telemetry equipment was not conducted because the Department decided to use the available warhead test slot on the test missile for a nontelemetry DOE test of the W78. The W88 is a warhead used by the Navy on the Trident II missile. Only 3 W88 stockpile flight tests (of the 12 planned) were conducted during the 4-year period from fiscal year 1992 through 1995. Flight testing of W88 warheads taken from the stockpile was halted for more than 1 year because an important safety study required for disassembly and inspection of the warhead at DOE’s Pantex plant lacked approval. A Nuclear Explosive Safety Study is required for each weapon type before DOE’s Pantex Plant can disassemble and inspect a weapon selected for testing. Without disassembly and inspection capability, surveillance tests, including flight tests of sample warheads from the stockpile (the nuclear components must be removed and replaced by the telemetry equipment), cannot be conducted. DOE and national laboratory officials are not concerned about the reliability of the W88 warhead because they have collected considerable data over the past few years by testing W88 warheads that had never been placed in the stockpile. Because the W88 warhead is a relatively new weapon, DOE officials believe that the information from these “new material” tests provides good reliability data. Of the nine weapon types, only the W88 warhead is considered by DOE to be of concern in relation to nonnuclear systems laboratory tests. These tests involve testing the nonnuclear systems—such as the radar systems and fuzes—in the weapon to detect defects due to handling, aging, manufacturing, or design. DOE officials said the Department should have conducted about 28 laboratory tests, but over the past 4 years, only 15 (or 54 percent) tests were performed. According to DOE and national laboratory officials, the tests were not conducted because of the absence of an approved safety study at Pantex. DOE officials said that in this case, the lack of testing reduces their confidence in the weapon’s reported reliability. DOE officials told us that they could not quantify the decrease in confidence. From the weapons selected for testing each year, one weapon of each type is selected to have individual nuclear and nonnuclear components destructively tested. Although many other components are tested (such as cables and electrical components), according to DOE officials, the five key components tested are the pit, the secondary, the detonator assembly, gas transfer system, and high explosive. Testing of four of these key components has been behind schedule in recent years. Only the high explosives tests have been conducted on schedule. The pit is a part of the nuclear package that, until 1989, was manufactured and tested at DOE’s Rocky Flats facility in Colorado. According to DOE officials, the Department ideally tests one pit per year per weapon type. In December 1989, the Rocky Flats facility ceased production operations. At first, DOE believed that Rocky Flats would reopen; however, in 1992 DOE decided to move pit tests to the Los Alamos National Laboratory. This lapse created a backlog of up to 4 to 5 years, but testing is currently nearly back on schedule. The secondary is tested at DOE’s Y12 facility in Oak Ridge, Tennessee. Ideally, one secondary should be tested per weapon type per year.