Another set of interesting statements: http://ptonline.aip.org/journals/doc/PH ... 47_1.shtmlRajeshA wrote:That is a very interesting Article in PhysicsToday:
The Chinese nuclear tests: 1964 - 1996: PDF
Stilman's visit to the SINR (05.04.1990) also produced his first insight into the extensive hospitality extended to Pakistani nuclear scientists during that same late-1980s time period. As we shall see, that cooperation, initiated earlier in the decade, led to a joint nuclear test in China soon after Stillman's departure.In 1982 China's premier Deng Xiaping began the transfer of nuclear weapons technology to Pakistan and, in time, to other third world countries. Those transfers included blueprints for the ultrasimple CHIC-4 design using highly enriched uranium, first tested by China in 1966.A Pakistani derivative of CHIC-4 apparently was tested in China on 26 May 1990.
For one thing, the Chinese probably sought deterrence. An American awareness of Chinese nuclear capabilities should lead to a more cautious American military posture around Taiwan and in the Pacific Ocean. Or perhaps it was an intelligence gimmick. Chinese scientists often displayed the inner workings of their technical devices to American visitors just to see how they would react. A raised eyebrow or a sudden scowl could confirm or discount a year's work. Maybe Chinese nuclear technology was no longer top secret. With the coming of Deng Xiaoping's regime around 1980, the proliferation of nuclear technology into the third world had become state policy. Perhaps it was time to let the Americans have a look.
Some one earlier in the thread asked/suggested # of testes by various N weapons states and number of tests India needs in the next round. I like the terms used here. The number of tests is dependent on how many tests needed for "proof-of-principle" and how many to "understand the nuclear dynamics". The The former is "proof for deterrence" and the latter the "proof of capability". "Proof of capability" is a poor substitute for "Proof for deterrence".The tour next brought Stillman face-to-face with another of the mysterious visitors to New Mexico: the director of the Southwest Institute of Fluid Physics—a euphemism for the Chinese high explosives test facilities. That institute has access to nine test facilities: three outdoors in the hills well beyond Science City and six containment vessels—large steel spheres that contain the energy released by a few pounds of high explosive. The explosives are wrapped around heavy metals simulating uranium, and the vessels are sealed so as to recover the valuable and sometimes toxic metals involved in the experiment. Four large containment vessels were located in Science City and two smaller ones were housed indoors at the Institute of Applied Physics in Chengdu. All the test facilities were carefully instrumented to collect reams of data. The Chinese scientists were not simply conducting proof-of-principle tests; they wanted to understand the dynamics of nuclear pit implosions.
BTW high energy LIF gives "Proof of capability" and to some extent "Proof of deterrence".
The Chinese scientists also understood the impact of thermal cycling on high explosives; they did not allow their nuclear weapons to remain exposed to sunlight for extended periods of time.
That led Stillman to raise a discussion of weapons security: "Do Chinese nuclear weapons contain design features or protective devices to preclude their unauthorized use?" The NINT director responded that terrorism was not a consideration in their nuclear weapons designs, that Chinese discipline precluded unauthorized use. At that time the Chinese weapons program relied on "politically reliable" guards, not electronics. The director did agree, however, that those safety and security policies needed to change. I suspect that such changes have since taken place.
Haa... this one is a gem. All roads lead to Rome!!They then revisited Science City, where Stillman learned far more than on his first trip there. For example, he was able to inspect the high-explosive test facilities. Adjacent to those test chambers were impressive flash x-ray machines, designed to illuminate implosions as they took place. Framing cameras nearby could operate at millions of frames per second. Pins within the imploding spheres delivered further data on implosion symmetry. The technology was state-of-the- art by any standard.
The following give insight to diameter of hand digged shafts which are expected to be of smaller diameter than digging with any sort of mechanized drilling rig. Thus Ramana's estimation of Shakti-1 shaft depth based on the WOP data on the area of metal sheet used for wall containment and estimated diameter (based on Shakti photo and other description in WOP) is in agreement with this Chinese data point. That calculation clearly indicated that the shaft was for significantly higher yield than 45kt.The VIPs attending the Stillman visit had flown in from Beijing. Most spoke excellent English, and it seemed like they all talked about their children's achievements in the US. Even the engineer responsible for drilling vertical test shafts at Lop Nur had worked in the US during World War II; by 1990 his children were all enrolled in America's top engineering schools. The midnight barbecue in the Chinese desert seemed much like a cookout in the hills above Los Alamos.
At the time of Stillman's visit, drilling rigs were at work on 2- to 2.5-m diameter holes for nuclear device emplacement. Drilling technology was archaic by US standards; the drillers were advancing through the underlying granite at a rate of only two meters per day.