Double-edged sword
Israel's nuclear weapons programme may prove to be more dangerous to its own citizens than to the Arab nations it is supposed to be aimed at. There are growing safety and environmental fears over the operation of its nuclear weapons establishment in the Negev, and concern that the design of its nuclear missile base near Tel Aviv may be fundamentally flawed, which may force the country to adopt a dangerous 'first strike' policy.
The launch of the long range Iranian Shahab 3 missile in July, along with the nuclear ambitions of Pakistan and India, has forced Israeli nuclear experts to review Israel's nuclear deterrent and determine if it is ready to meet the possible threats of the next century instead of the perceived threats of the last generation.

In addition to deterring Soviet intervention in an Arab/Israeli war, the Israeli bomb was developed when the biggest threat to Israel was its neighbours and the nuclear arsenal was targeted towards neighbouring Arab capitals and defeating their armies on the ground. The result was a focus on small yield nuclear weapons which could be used safely near Israeli borders, along with weapons large enough to destroy capitals or strategic centres behind enemy lines.

However, the recent agreements between Israel with its neighbours, and the growing threat from distant enemies like Iran, have forced the Israeli Ministry of Defence to review nuclear strategy again. The result may be a change where tactical nuclear weapons will be less important, longer range missiles will be developed, and greater emphasis will be placed on putting the Arrow anti-ballistic missile system in place to combat these enemies from afar.

Dimona Remains in the Picture

Any change in strategy and development of new weapons will mean more work for Dimona. However, after about 35 years in operation, there is growing concern even within the Israeli government that Dimona is no longer able to meet the needs of an expanding nuclear arsenal. According to internal Dimona reports, the nuclear reactor is suffering severe damage from 35 years of operation. This damage has come from the neutron radiation from the reactor core and this bombardment has changed the reactor structure at the atomic level. Metal supports have become brittle and warped as the neutrons have created gas bubbles in the metal itself. Although some parts have been replaced, there is considerable debate as to whether the whole reactor should be decommissioned before an accident could take place.

The risk of Dimona doesn't end there. Several technicians and their families have sued the government for illnesses caused by accidents at the facility. In addition, analysis of Russian satellite imagery from 1989 shows that the facility has a major pollution problem. This imagery was taken by the MK-4 camera system which looks specifically at near infrared light. This part of the light spectrum allows analysts to separate camouflage from real vegetation. It also shows the health of vegetation, which makes it a popular tool for scientists, farmers, and environmentalists.

According to computer enhancement, the area just west of the reactor shows an unnaturally barren zone. According to reports, this is where the waste treatment facility is and where the toxic byproducts appear to be stored. Although the imagery can't determine the level and type of pollution, since Dimona uses the same plutonium extraction processes as the United States, the Hanford plutonium production complex in Washington State in America provides an example of the environmental risks found at such a plant.

Plutonium production is one of the most dangerous processes in the world and according to some estimates, each kilogram of plutonium produced creates 11 liters of toxic, radioactive liquid, which has defeated attempts to neutralize it. At Hanford, hundreds of acres are highly contaminated from decades of plutonium production. These byproducts are corrosive and very hot from the absorption of radiation. This heat makes it more corrosive and better able to corrode the storage containers. In addition, the flammable radioactive gases which are produced by the liquid also create so much pressure that the containers can rupture. Nor can this chemical waste be easily neutralized since the radioactive process means that the chemical composition is constantly changing as radioactive isotopes transmute into other elements. The result is that these radioactive isotopes leak into the soil, ground water, and air. Some of the problems are localized and effect the plant workers while other radioactive pollution can travel away from the site through ground water or on the wind.

Nor is all the risk from radioactive waste. One and a half tons of plutonium are believed to be in waste that was dumped into the ground. In addition, industrial solvents and other chemicals, which are hazardous and known carcinogens like carbon tetrachloride and tributyl phosphate were used in the extraction process and discharged into the ground. Finally, the reprocessing plants have internal radiation levels which are deadly and can't be readily be cleaned up. According to experts, the air filters of the Hanford B-plant alone probably have 100 million curies of radioactive cesium and strontium in them.

Despite problems at Dimona, the government is loath to decommission the facility despite the fact that it will join the 61 nation UN Conference on Disarmament talks on banning the manufacture of nuclear weapons materials in 1999. The problem isn't just Israel's desire to produce more plutonium, but a need to maintain its supply of tritium, a heavy isotope of hydrogen. This isotope is critical for Israel's nuclear weapons, including boosted fission weapons (which according to some reports includes the whole nuclear arsenal) and neutron bombs. In boosted weapons, this gas is injected into the center of the bomb just before ignition in order to provide the chain reaction with more neutrons. This allows scientists to produce bombs with less plutonium and makes them smaller and more powerful. These factors are critical in producing the light weight warheads on missiles and will become more important if future nuclear strategy calls for a conflict against a distant enemy, where warhead weight is critical in order to maximize missile range and yield. Just as important, in a scenario where Iran may use nuclear weapons against Israel, boosted nuclear weapons are more immune to unwanted fission due to the neutron flux experienced during a nuclear war.

Tritium is also critical for neutron bombs, which would be considered the nuclear weapon of choice against massed armor formations along Israel's borders. In neutron bombs the tritium is placed in a capsule with deuterium outside the core of the bomb while the bomb is designed to minimize neutron absorbing materials. When the bomb provides enough heat and pressure, the two hydrogen isotopes fuse to create helium and a powerful neutron. This cascade of neutrons can penetrate heavy tank armor and kill the occupants even though the heat and blast damage from the bomb would be much less. A similar type of warhead can be used in a ballistic missile defense, where the nuclear tipped anti-ballistic missile would explode near the incoming nuclear missile. In addition to the electromagnetic pulse destroying the warhead's electrical components, the flux of neutrons could cause unwanted fission, which would render the warhead ineffective.

The problem with tritium is that its half life is 12.3 years. Since it decays into a helium atom which absorbs neutrons, even a small change in the ratio of tritium stored in a bomb can make it a dud. Consequently, these weapons have to be constantly maintained, the tritium renewed, and the helium removed. This means that every year Israel must replace 5.5% of its entire tritium stock just to keep its current weapons stock operations. Additional tritium for new weapons would place even more demands on the reactor.

Although the amount of tritium in Israel's arsenal is secret, the US Department of Energy has released information on how much tritium is used in various weapons designs. They estimate 4 grams in a boosted nuclear weapons and 10 to 30 grams in tactical nuclear neutron bombs. Assuming Israel has 200 weapons (all of a boosted design) with an average of 4 grams in each one and 40 neutron bombs with 20 additional grams, the total Israeli inventory is at least 1,600 grams. That means Dimona must replace at least 88 grams of tritium each year. Since tritium production must substitute for plutonium production, Dimona must forgo production of over 7 kilograms of plutonium each year; enough to produce two bombs. Without Dimona, Israel would need at least a 30 to 40 megawatt nuclear reactor just to keep tritium in the current arsenal. This is one of the biggest reasons why the government has decided to keep Dimona running despite the risk.

The importance of tritium to Israel is evident by analyzing satellite imagery of Dimona. A comparison of satellite imagery from the 1971 and 1989, and 1997 shows very little change in the Dimona facility over the decades. On the east side of the facility, however, is one building that was built between 1971 and the late 1980s. Although there is nothing visible from space that indicates its use, based on what Mordecai Vanunu said about the construction of Unit 93, this is probably the facility that extracts tritium from irradiated lithium. This tends to confirm the importance of tritium to Israel's nuclear arsenal.

There are also reports that Israel is attempting to learn about a new method to produce tritium that was developed by India. This technology separates tritium from the heavy water used as a moderator in many nuclear reactors. This method would allow Dimona to continue plutonium production without risking tritium production. It could also be used to produce tritium at other reactors.

The Jericho II at Zachariah

Although Dimona is the home of Israel's nuclear material, it is the missiles at Zechariah that will probably be used against distant enemies like Iran. The heart of that deterrent is the Jericho II missile which has an estimated range of 5,000 km.

Nuclear-tipped Jericho missiles are deployed in bunkers west of Zachariah several miles southeast of Tel Aviv in the Judean hills. The base is built in a limestone region with numerous caves and small hills which have been hollowed out to house the Jericho II, its support vehicles and ancillary control equipment.

Its predeccessor, the Jericho I missile, was developed in the 1960s, initially with the help of the French aviation company, Dassault. Jericho I was intended to have a maximum range of 500 kilometres and the first firing of a single-stage missile took place 1st February 1965. In March 1966, a two-stage missile was successfully tested. French collaboration stopped in January 1969 due to the total embargo on weapons sales to Israel, However the Israelis continued, working with South Africa, and in 1987, testflew an advanced missile, with a range of nearly 1,500 kilometres.

According to some reports Jericho II is guided to the target with a radar which compares the target image with information stored in its memory.

Based on Russian satellite imagery showing a Jericho II outside during training, the missile transporter is 16 meters long, 4 meters wide, and 3 meters high. The missile transport deploys with three support vehicles. One of these vehicles is probably a guidance programmer and power vehicle connected to the transporter by cable. The other two vehicles are for firing control and communications.

Based on a three dimensional analysis of the missile base, the missile transports would sally forth from three bunker entrances and deploy throughout the country side or in cul-de-sacs nearby. There are signs of major excavations of the hills before the open sides were closed with a reinforced concrete slope, covered with dirt, and reseeded. The road leading to the bunker entrances gently dip and turn under the concrete slopes. This curving entrance and the hills around the entrance makes it difficult for a low flying aircraft to drop a conventional bomb into the entrance to breach the door or cause a cave-in.

One of the interesting features of this site is that there appears to be only three major entrances to the three separate bunkers. Although there appear to be other roads leading to the underground bunkers, those entrances aren't as protected and may not even be entrances. This raises the question of whether a few accurately placed nuclear bombs can stop Israel's missiles from deploying. In addition, the nature of the entrances indicates that the bunkers aren't far underground and that the only protection is provided by the hills that they are built into. Of course, the bunkers could be interconnected by tunnels so the missiles could exit undamaged entrances, but tunnels are long and very vulnerable to damage from shifting ground caused by a nuclear ground blast. For instance, the underground tunnels connecting the American Titan II missile silo to the control center were made with 6 inches of hardened steel, contained expansion joints, and were suspended on springs. Yet, engineers expected them to buckle under external shock and vibration from a nuclear ground blast and possibly become impassable to foot traffic.

Since there is no way to fire the missiles from underground, the missiles will be vulnerable to an enemy missile attack while they are outside. Currently the Shahab 3 is considered inaccurate and Iran doesn't have nuclear weapons (although there are reports that they acquired some during the break up of the Soviet Union). However, if this changes, Israel would have to change its nuclear strategy and even consider a nuclear first strike if it was threatened with losing its nuclear capability. This vulnerability has led some in the Ministry of Defense to consider future deployments of missiles in hardened silos since an accurate, nuclear tipped, Iranian missile is becoming a disturbing possibility. There is also additional work on making the missile itself less vulnerable in a nuclear environment.

Although the Shahab 3 test showed some problems which are keeping it from immediate deployment, the changing environment in the Middle East means Israel must reassess its nuclear strategy. Over the next few years. Israel is expected to modify its nuclear policies to be more strategic in nature and more responsive to nuclear threats. This reassessment of the country's nuclear strategy will have an impact on nuclear weapons development and deployment in the near future, the fate of Dimona, and on Israel's participation in a treaty limiting the production and spread of nuclear materials.

First published in Pete Sawyer's 'Assignments Unlimited' homepages Harold Hough & Pete Sawyer September 1998. Harold Hough is a freelance journalist based in Tucson, AZ. He is an expert on analysing satellite images and contributes to Jane's Intelligence Review.

Terms and Conditions of use
Dimona as seen by an American spy satellite in 1971. More recent Russian pictures from 1997 show that the only major addition to the site is the construction of a building on the east side of the facility, probably for tritium separation . In 1989, a Soviet satellite looked at the near infrared part of the electromagnetic spectrum, which clearly shows the health of vegetation. This computer enhanced image revealed a barren spot where reports placed the waste treatment facility. The dead vegetation was probably the result of the highly toxic nature of the plutonium byproducts produced at Dimona.
A computer-enhanced image of part of the Zachariah base, with the nuclear gravity bomb storage bunkers clearly visible. Most of the facilities are underground. The compactness and limited hardening of the Zachariah base make it vulnerable to a crude nuclear device, which, if detonated over the one of the entrances to the underground bunkers, would probably damage the bunkers enough to prevent the missiles stored inside from being used.
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