Posting the primary articles, I have that places credible doubt on the S1 TN test. All have been posted before, apologies for the long post. Some of the original links in various news portals are now defunct.
Pokhran-II thermonuclear test, a failure
K. Santhanam and Ashok Parthasarathi
A critical analysis of the technical facts can lead to no other conclusion. BARC must learn to tell the nation the truth.
Several inaccuracies in the claims made by BARC and in the articles published in the press, including The HinduPokhran-II need to be corrected. We have hard evidence on a purely factual basis, to inform the nation that not only was the yield of the second fusion (H-bomb) stage of the thermonuclear (TN) device tested in May 1998 was not only far below the design prediction made by the Bhabha Atomic Research Centre (BARC), but that it actually failed.
All the five nuclear tests conducted in May 1998 were undertaken through a joint BARC and Defence Research and Development Organisation (DRDO) team. A.P.J. Abdul Kalam and R. Chidambaram assigned the DRDO team the critical responsibility for all the field instrumentation to record seismic data from all the tests: this was vital in estimating the yields. The seismic sensors were placed at many points in the device shafts and out to a radius of 2.5 km. The sensors and instrumentation were calibrated several hundred times and perfected. They fully met international standards and were acknowledged to be so by BARC.
The DRDO was thus deeply involved in all the seismic measurements and was fully aware of the BARC-projected readings vis-À-vis its own measurements. One of the authors, Dr. Santhanam, was personally aware in detail from key BARC scientists of the core designs and hence the projected yields. Consequently, the reference in a report published by The Hindu on August 28 (headlined “’Fizzle’ claim for thermonuclear test refuted”) attributed to a “former senior official of the Vajpayee government” that I was “not privy to the actual weapon designs which are highly classified,” was incorrect.
The DRDO also designed and conducted numerous tests of the High Explosive (HE) Trigger of the TN test. BARC scientists witnessed these tests, took copies of test records, and expressed satisfaction with the DRDO’s work.
Over May-October 1998, DRDO produced a comprehensive report of actual seismic readings vis-À-vis values predicted by BARC, mentioning why the former showed considerably lower yields than the latter.
The DRDO report was discussed at a meeting called by National Security Adviser Brajesh Mishra in late 1998. The meeting was attended by Dr. Chidambaram and Dr. S.K. Sikka, the scientific head of the BARC team; Mr. Kalam, the Director-General of the DRDO; Dr. V.K. Aatre, the Chief Controller of the DRDO, Dr. Santhanam, and the Chiefs of the Defence Services. Despite a long discussion, largely between the DRDO and BARC, both stuck to their positions on the TN device yield. Thereafter, the NSA took a ‘voice vote’! This was highly unusual because the matter was technically very complex and the services were ill equipped to give an opinion on yields. Most surprisingly, NSA concluded saying government would stand by Dr. Chidambaram’s opinion.
Dr. Chidambaram’s claims and those in Atomic Energy Commission statement reported on September 16 under headline “No reason to doubt the yield of 1998 nuclear test: AEC” are wrong. BARC basically argued that the geological structure of Pokhran was different from test sites elsewhere. However, the DRDO and BARC utilised the same published information in their calculations of TN device yield. BARC accepted the DRDO’s yield estimates of the fission (A) bomb, but not of the TN device, although the latter’s shaft was situated only a few hundred metres from the former’s shaft. Globally, geological structures do not change dramatically at such small separations. So BARC’s argument to “explain” a lower TN yield is untenable.
Dr. Chidambaram’s statement that “the post-shot radioactivity measurements on samples extracted from the test site showed significant activity [levels] of radioisotopes Sodium 22 and Manganese 54, both of which are byproducts of a fusion reaction rather than a pure fission [device]” is incorrect. He should indicate the exact level of activity instead of merely saying “significant activity” as the activity level determines whether a fusion reaction of the magnitude claimed by BARC actually occurred.
Dr. P.K. Iyengar, a former Chairman of the Atomic Energy Commission and a former Director of BARC, informed me that trace levels of these same isotopes were detected in Apsara, a pure fission reactor not involving any fusion at all. This is the exact opposite of Dr. Chidambaram’s claim.
Dr. Chidambaram’s statement that “from a study of this radioactivity and an estimate of the crater radius confirmed by drilling operations at positions away from the shaft, location, total yield and break-up of fission and fusion components, could be calculated” is extremely surprising. First, after the TN test, its shaft remained totally undamaged: if the fusion stage had worked, the shaft would have been totally destroyed. Secondly, the A-frame sitting astride the mouth of the shaft, with winches to lower and raise personnel, materials and so on, also remained completely intact. If the fusion stage had worked, the ‘A’ frame would also have been totally destroyed.
As for radioactivity levels, senior BARC radiochemists who undertook radio-assay of fission products in samples similarly drilled at Pokhran-I (of May 1974) told Santhanam that the yield announced to the media was substantially higher than what they had submitted to Dr. Raja Ramanna. Dr. Chidambaram must publicly substantiate any claim that it did not occur in the TN test along with justification data.
Dr. Chidambaram states: “BARC scientists worked out total yield of TN device as 50 +10 kt — consistent with design yield and seismic estimates.” However, he subsequently asserts: “BARC experts established DRDO had under-estimated yield due to faulty seismic instrumentation.” BARC cannot eat the cake and have it too.
The fission bomb yield from the DRDO’s seismic instrumentation was 25 +2 kiloton and left a crater 25 metres in diameter. If the TN device had really worked with a yield of 50 +2 kt, it should have left a crater almost 70 metres in diameter. Instead, all that happened was that sand and mud from the shaft were thrown several metres into the air and then fell back, forming a small depression in the shaft mouth. There was no crater.
This factual analysis reveals India’s decade-long, grim predicament regarding the failed TN bomb and so our Credible Minimum Deterrent (CMD). No country having undertaken only two weapon related tests of which the core TN device failed, can claim to have a CMD. This is corroborated by fact that even after 11 years the TN device has not been weaponised by BARC while the 25 kiloton fission device has been fully weaponised and operationally deployed on multiplate weapon platforms. It would be farcical to use a 3500-km range Agni-3 missile with a 25 kiloton fission warhead as the core of our CMD. Only a 150 – 350 kiloton if not megaton TN bomb can do so which we do not have.
(K. Santhanam was Project Leader, Pokhran-II. He worked as a physicist at BARC for 15 years. Later he was Chief Adviser (Technologies) in DRDO for 14 years and was then also Director General, Institute for Defence Studies and Analyses, New Delhi. Ashok Parthasarathi, the co-author of this article, was S&T Adviser to Prime Minister Indira Gandhi and deeply involved in Pokhran-I, of May.)
To test or not to test
K. Santhanam and Ashok Parthasarathi join the scientists’ debate
WE respond to R. Ramachandran’s article, “Why There is No Case for Further Nuclear Tests” (The Hindu, September 25, 2009). His main points are: “technical information published by the Department of Atomic Energy does not show Pokhran-II (P-2) was unsuccessful”; (b) an assertion: there are compelling arguments against need for resuming (thermonuclear (H-bomb) device testing). Even if it was so i.e. even if the thermonuclear test was a failure (c) “the DAE employed different techniques to estimate test yields (i.e. power outputs); (d) yield values from other five tests “are stated to be”! (by BARC) consistent with its original estimate of 60 kilotonnes (a bomb’s output equal to 60,000 tonnes of TNT) for the two main tests on May 11, 1998, i.e. a 45-kt (thermonuclear or TN) device and a 15 kt A-bomb exploded simultaneously. Of these, post-shot Radio-Chemical Method (RCM) (of device yield measurement) considered most accurate; (e) both A-bomb “trigger” and main H-bomb produce a type of nuclear particles called Neutrons.
However, H-bomb devices, produce more Neutrons than A-bombs. This leads to considerably larger amounts of two artificially created radio-isotopes — Manganese 54 and Sodium 22 — being produced by the TN device than the A-bomb. This higher ratio of Manganese 54: Sodium22 in the H-bomb explosion does provide an “idea” of the A–vs – H-bomb/device yields (no numbers at all; only “an idea” of relative yield magnitudes); and this is supposed to be nuclear “physics”!).
The writer’s justification: “The absolute values and scale of this higher ratio, (in TN device case) withheld for “obvious” sensitivity reasons, but qualitative difference in levels is evident”. The writer’s source: a BARC Newsletter article (July 1999). It is not a peer-reviewed scientific journal.
(f) His last technical “scoring-point” is a “desperate explanation” of why and how, while the “pure” A-bomb of the BARC-claimed yield of only 15 kt – when its collaborator in P-2 – DRDO, and our top scientific institutions, as also numerous top nuclear weapons laboratories worldwide, have rated it at much higher 20-25 kt, produced a crater 25 meters in diameter — which the BARC dishonestly-claimed yield of only 15 kt could never have produced — the BARC–claimed -to-be-“successful” -H-bomb-of-45 kt, – thrice as powerful – even at BARC de-rated 15 kt yield pure ‘A’ bomb – produced no crater at all when a genuine 45 kt TN device, even common sense tell us, should have produced a gigantic crater. He says “at some low enough TN device emplacements, i.e. deep enough shafts, there would (only be) upheaval within the shaft) but no material... There would be no crater”!
Here is our response. As regards Mr Ramachandran’s regurgitation of the BARC argument that it used different techniques in yield estimation, he was not personally involved in the tests. Mr Santhanam was one of the four key scientists directing P-2 from day 1. So, he can only say “45 kt fusion device and 15 kt fission bomb “are stated to be” (by BARC) “consistent with original estimates”. On what basis can he say this when those estimates are highly classified?
As for post-shot RCM being “most accurate” (for nuclear explosions yield (power) estimation), former BARC Director’s Radiochemistry Division (RCD) told us: “I measured yield of (P-I) (1974) using Mass Spectrometry (MS) method. A microgram of plutonium was separated from sample taken near core of device, and its isotopic composition — which does not change with various transformations caused by nuclear tests — measured.
The MS technique considered internationally the most accurate and reliable method for yield estimation even more accurate than RCM (which the writer tomtoms about, without knowing about nuclear weapon yield measurement). The MSM is far less sensitive to major weakness of the RCM. That’s why Dr Ramanna, former BARC Director, former AEC Chairman, and Mission Director P-1, insisted on the MS method for (P-1) yield estimation in 1974. If the MS method was used in (P-2) also, why exclude it in the BARC’s briefing to Mr Ramachandran?
Using S.B. Manohar’s article (BARC Newsletter, July 9, 1999) on RCM to determine TN device yield lacks credibility as it is an inhouse publication.As for the BARC argument, the TN device produced “copious amounts” of Sodium-22 and Manganese-54 isotopes “characteristic of fusion reactions”, in the absence of exact numbers, it is an unsubstantiated assertion. A “fizzled” TN device also produces “copious amounts” of these isotopes.
Moreover, mere presence of isotopes is not a quantitative yield measure. It can at best be a qualitative indicator. This obfuscation becomes worse when the writer said, “…it does provide an idea of the comparative (i.e. H-bomb vis-a-vis A-bomb) yields”! As a scientist, he ought to know that precise quantified statements are core of science and scientific credibility. Using an imprecise phrase like “copious amounts” begs the question.
“The classified exact plutonium mass in the core of the (P-1) device may not have been known to the RC Division of BARC after P-1. However, RC measurements in RCD’s report indicated yield are significantly lower than Ramanna’s and Chidambaram’s claim. So, RCD’s report on yield of (P-1) was frozen by Ramanna and Chidambaram and consigned to the archives”!
The writer then moves to our statement that had TN test really worked, the 120-meter deep shaft at the bottom of which the TN device was emplaced, would have been totally destroyed and its deepest portions even vapourised. There would, in addition, have been enormous surface damage to even massive 2-tonne and 8-meter high tripod “A-frame” astride the shaft’s mouth. This “A-Frame” has a complex set of winches and pullies connected at their bottom to a lift-like “container” to lower and raise personnel, equipment and materials to and from the bottom of the shaft when the TN device is being assembled would have been shattered.
Both were totally intact after the TN device test. Mr Ramachandran has ignored this damning evidence that the TN device failed! He moves to the issue of cratering, using the BARC’s arguments on geological and TN device-related factors preventing crater formation by 45 kt yield TN device. Based on 25 metre diameter crater formed by 20-25 kt “pure” A-bomb (which BARC rates at only 15 kt yield), the DRDO calculated a 60-70 meter diameter crater should have been formed by the latter fully confirmed by the ARC. Thus, one needs a cogent response from Mr Ramachandran why and how such a phenomenon is supposed to have occurred.
The super hi-tech ARC, independent of both BARC and DRDO with a 365 x 24 x 7 operated very large seismic array, 10-15 per cent more sensitive and accurate than DRDO’s, measured all the seismic signals from all P-2 tests. Their calculations, far more sophisticated than BARC’s, indicated a TN device yield at only 20 kt max.
Mr Ramachandran then moves to the article by former DRDO chief and strategic affairs analyst, V.S. Arunachalam and K. Subramanian, respectively (The Hindu, September 21). They say, even a 25 kt A-bomb’s damage on enemy city targets with large populations would be ‘unacceptable’ to any adversary and so such A- bombs would be enough for us to deter even China having 200 deployed H- bombs of 3.3-5 megatons yields each.
Surprisingly, though they argued for decades that H-bombs were central to our Credible Minimum Deterrent (CMD), they suddenly say A-bombs (which cannot yield more than 80 kt max) are enough. Why? Sour grapes following the TN device failure and no weaponisation for the last 11 years! China would be totally undeterred by our piffling A-bomb “arsenal” of yields.
We reiterate our view, fully shared by the overwhelming majority of our nuclear scientists, strategic analysts and, above all, our military, that a sole A-bomb arsenal is grossly inadequate to be a CMD against China; only TN bombs can do so. Otherwise, why did four Prime Ministers (including Mr Vajpayee and his NSA Mr Brajesh Mishra) direct the top of BARC-DRDO leadership — Mr Kalam, Mr Chidambaram, Mr Santhanam and Mr Kakodkar — that one Pokhran-II test at least must be a TN device?
The current “controversy” over the failure of the sole H-bomb test of P-2 is the only case of the long history of DAE, BARC being “highly economic with truth” and using such “economy” to protect themselves from public criticism of major failures in various programmes and projects. The failures have been screened from public gaze on unwarranted and secrecy grounds.
Worse, the DAE has tried to hide facts from successive governments, Parliament and the people, causing damage to our nuclear programme and national security. The Prime Minister and the Union Cabinet must help stop this. The nation waits with bated breath if they can or will.
P K Iyengar
The recent controversy that has erupted regarding the 1998 Shakti or Pokhran-II tests, after the statement of Dr. K. Santhanam about their yield, has once again brought into focus the need for further nuclear tests in order to have a credible nuclear deterrent. The issue gains fresh stimulus because of the expectation that the new US Administration will get the Comprehensive Test Ban Treaty (CTBT) ratified by the US Congress, and put pressure on India to sign it. The pressure may be more difficult to withstand this time, compared to 2000, because of expectations and complications arising from Indo-US Nuclear Deal.
There may be political arguments both for and against signing the CTBT, and for maintaining a credible nuclear deterrent. But, once we have decided on a policy of nuclear deterrence, which will require weaponisation, then, scientifically, we have no option but to continue testing. It is the scientific case that I wish to make here.
To refresh people’s memories: three nuclear devices were detonated simultaneously on May 11, 1998: a pure fission device, a thermonuclear device, and a sub-kiloton fission device. The pure fission device was similar to the Pokhran-I device, and was reported to have a yield of 15 kt. A typical thermonuclear device has two parts: a ‘boosted-fission’ trigger, and the actual thermonuclear part, comprising LiD fuel. The fission trigger is an atom bomb that produces enough radiation pressure to make the ‘hydrogen bomb’ ignite. In addition, one can use a spark-plug; this spark-plug is just some fissile material like plutonium (Pu) placed around the fusion core which, when it fissions, heats the core and aids the fusion process. The first hydrogen explosion, Mike, carried out by the US in 1952, had a spark-plug. It is very likely that the thermonuclear device of 1998 also had a spark-plug.
Therefore, the total yield of the thermonuclear device is the sum of the fission yield from the boosted-fission, the fission yield from the spark-plug, and the actual fusion yield from the LiD. The latter proceeds by the Li first being converted to tritium by absorbing a neutron arising from the fissions, and this tritium then fusing with the deuterium (D) to form helium (He).
Now, if one goes by the number for the total nuclear yield put out by the Department of Atomic Energy following the 1998 nuclear tests, the thermonuclear device alone was around 50 kilotons. To know how successful the fusion was, we must know how much of this came from the boosted-fission and spark-plug, which are fission reactions, and how much from the actual fusion of tritium to form helium. In earlier designs the booster has been designed for as much as 45 kt yield, so if we take the booster yield as even 30 kt, a reasonable assumption, then the fusion yield must have been 20 kt. One can then calculate that the amount of LiD that must have burnt to achieve this yield would be 400 grams or only around 500 ml. This is small volume, and typically one puts in a lot more of the fusion material in the core — in kilograms.
Therefore, if only 400 gm burnt, then the fraction the total fuel that burnt must have been small — perhaps as little as 20 per cent. Clearly, this is not a very efficient thermonuclear device. Now, the unburned LiD fuel would still have been converted to tritium by the capture of neutrons. If most of this tritium did not ‘burn’, i.e. fuse to form helium, then a lot of tritium should have been detected in the soil samples from the test site. This is what seems to have happened, even though it is not confirmed.
The new revelation by Dr. Santhanam is that the actual total yield of the thermonuclear device (i.e. the boosted-fission part plus the fusion part) was only 60 per cent of the design value (of 50 kt), i.e., around 30 kt. This is also consistent with the yield values obtained from seismic data according to international sources. If we accept Dr. Santhanam’s number, coming as it does from one of the core members of the Pokhran-II tests, then the situation is even more serious. This suggests that the thermonuclear burn may have been marginal or may not even have occurred at all. This has very serious implications for our weaponisation programme and deterrence philosophy, and certainly invites much closer, detailed, technical scrutiny. Of course, none of these numbers are very accurate, but 10 kt more or less, in one direction or the other, will not materially alter these conclusions.
It is true that the subsequent drilling operations and radioactive measurements have shown the presence of fission fragments and isotopes produced by fast neutrons. But these fast neutrons could have come from, the fission as well as the fusion. Further, the booster itself has tritium which would have contributed to the activity generated by fast neutrons. Therefore presence of these isotopes cannot unequivocally confirm that the fusion secondary has really worked. Attempts have also been made to derive the fusion yield from a radiochemical analysis of the isotopes.
However, the methodology employed in the radiochemical analysis, is complex. Approximations made in integrating the flux distribution, extent of the cavity, and a statistical variation in the samples taken by drilling, introduce large error. Nobody can vouch for the geometry of the cavity or their debris. BARC scientists have themselves indicated an error of 40 per cent on their number of 50 kt. Under this circumstance, this radiochemical method is not absolute proof for the yield of the explosion.
Conduct more tests
Because of these considerations, I have held the view that we should repeat this experiment, especially the thermonuclear part, to have full confidence that the secondary has been ignited and not simply triggered. In a fusion device the burn, if properly ignited, is continuous in the volume of the secondary and therefore the efficiency of the fusion system should be higher. Since that is not well established, logically and scientifically it is better to conduct more such tests to establish the results and to achieve greater efficiency.
When we go from testing a device to weaponising it, there will be a lot of changes in the hardware configuration, because it has to match with the delivery system – either a missile or an independent bomb. Weaponisation also means certifying to the user the yield and reliability. More gravely, we must be able to convince not just ourselves but the entire world that we have mastered the thermonuclear weapon, and are fully capable of deploying it.
If there is any uncertainty in their minds regarding the efficacy of our nuclear deterrent, the entire concept of deterrence fails. This assumes even greater importance since we have declared a ‘no first use’ policy. It is unscientific to embark on a long programme of weaponisation, and develop elaborate plans for maintaining a credible nuclear deterrent, all based on just one, low yield, thermonuclear test. When we do not do this for the Agni or Prithvi missiles, or even the Nano car!, why would we want to take this risk for nuclear weapons?
I am sure that the BARC scientists themselves, like their DRDO counterparts, would prefer to take a more conservative approach and test further to refine their designs and their capabilities. This is the scientific way. It would be wrong for the government to pressure the scientists to put a premature end to nuclear tests, for political expediency.
On top of all these uncertainties, we have the political pressure for India to sign the NPT, the CTBT, and the FMCT. Whatever the Government may claim, it is unlikely that a future government can ignore the assurances given by the present Government, or afford to withdraw from these treaties, after establishing the very capital-intensive nuclear power programme, with foreign investment. It therefore requires a systematic and deeper study to plan a long-term strategy, keeping in mind that the number of countries with nuclear weapons is only likely to go up, and the weapon powers are unlikely to agree for universal nuclear disarmament.
Arguments for CTBT
Technical arguments for signing the CTBT often run as follows: we have confirmed the validity of our computer simulations using data from Pokhran-I and Pokhran-II. These computer codes can therefore be used to design nuclear weapons. If any further changes are made to these computer codes, we can revalidate them using sub-critical tests that are not barred by the CTBT. Therefore it is OK to sign the CTBT.
First, it should be remembered that of the total of six tests, five were fission devices, and only one was a fusion device. The physics of fission and fusion devices, and hence the computer codes used to model them, are very different. Therefore, for the fusion device, we really have only one test, that too of doubtful success, with which to check the computer simulation.
One is an alarmingly small number. In any case fusion (and, for that matter, fission) devices are extremely complex systems with a large number of variable parameters. It is unwise to benchmark a computer simulation of a full-scale explosion using data from just one test. Sub-critical tests are no substitute for full-scale tests, especially when we talk of weaponising. This is all the more so, because of the disastrous consequences of even one failure. Therefore, if we want to weaponise we cannot depend on computer simulations alone: we have no option but to test further.
I would like to emphasise that thermonuclear devices are better for weaponisation and deployment, because they are compact, light, use less sensitive material, and offer better safety features. For example, a boosted-fission thermonuclear device can be as light as 200 kg, compared to a pure-fission device that can weigh as much as 800 kg for the same yield.
It is for this reason that most of America’s nuclear weapons are fusion weapons. Therefore my focus here has been on the inadequacy of just one thermonuclear test, of low yield, for weaponisation. If the Americans are pressuring us to sign the CTBT, it is precisely for the reasons stated above: one could thus freeze India as a non-weapon country.
Given the earlier doubts on the yield raised by many experts, and now by Dr. Santhanam,
given the need to evolve an efficient thermonuclear device with a large burn percentage, given the necessity of hardware changes that are needed to match with the delivery system, and given the need to convince the world and particularly potential enemies that we have mastered all aspects of the thermonuclear weapons and have a credible nuclear deterrent, it is a scientific imperative that we should test not just once but repeatedly.
To blind oneself to this imperative could be disastrous. We would do well to remember what the famous American physicist, Richard Feynman, said in the report on the 1986 Challenger shuttle disaster: “For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.” Nor can the world.