Category Archives: Nuclear physics

A Trend of Increasing Neutron Count Rates Detected at Chernobyl

May 6, 2021All Posts, Nuclear Cleanup, Nuclear physicsChernobyl, neutron streaming, Room 305/2Drummer

Peter Lobner

The accident at Chernobyl Unit 4 occurred on 26 April 1986. A post-accident view of the Unit 4 reactor building is shown below.

*Post-accident west-east building cross-section of Chernobyl Unit 4.*
*Source: G.G. Pretzsch, et al. (2002)*

A temporary “sarcophagus” was hastily erected around Unit 4 to provide some protection for the recovery workers and the public, to stabilize the damaged building and protect its interior from the effects of weather. Since November 2016, Unit 4 has been fully enclosed within the more substantial New Safe Confinement (NSC) building. You’ll find a good overview of the NSC at the Chernobyl Gallery website here: http://www.chernobylgallery.com/chernobyl-disaster/new-safe-confinement/

On 5 May 2021, Richard Stone, writing for Science magazine, reported online that, “Sensors are tracking a rising number of neutrons, a signal of fission, streaming from one inaccessible room, Anatolii Doroshenko of the Institute for Safety Problems of Nuclear Power Plants (ISPNPP) in Kyiv, Ukraine, reported last week during discussions about dismantling the reactor..….ever since its (the NSC) emplacement, neutron counts in most areas in the Shelter have been stable or are declining. But they began to edge up in a few spots, nearly doubling over 4 years in room 305/2, which contains tons of FCMs (fuel containing material) buried under debris.” Modeling by the ISPNPP suggests that the increasing neutron count rates may be related to the gradual drying of the FCMs. Other phenomena may be contributing, such as the observed long-term disintegration and change of consistency of some FCM formations in the rubble.

The ceiling of room 305/2 was directly under the Unit 4 reactor core. From the force of the accident, that ceiling was driven down by almost four meters.

The original inventory of uranium in the Unit 4 core was about 180 metric tons enriched to 3%. In a French-German study of the condition of the Chernobyl sarcophagus, authors G.G. Pretzsch, et al. reported that about 96% of the original nuclear fuel inventory remained inside the sarcophagus. The distribution was estimated as summarized in the following table. The authors estimated that about one-half of the total fuel mass was in Room 305/2.

*Post-accident estimated distribution of fuel masses at*
*Chernobyl Unit 4. Source: G.G. Pretzsch, et al. (2002)*

The condition of room 305/2 is described in considerable detail (in Russian) in the 1998 IAEA Report INIS-UA—062, “Room 305/2 Block 4 of the Chernobyl NPP: Its Condition, Assessment of the Amount of Fuel.” The room is a jumble of damaged building structural elements, reactor parts, and FCM in various forms, including “lava” flows.

*Physical model of sub-reactor room 305/2.*
*Source: A.A. Borovov, et al. (1998)*

The authors reported on estimates developed using a variety of methods, as summarized in the following table, and concluded that the best estimate for room 305/2 was ≥ 60 metric tons of uranium.

*Estimates of the amount of fuel material in sub-reactor room 305/2.*
*Source: A.A. Borovov, et al. (1998)*

You’ll find my machine translation of this IAEA report to English, including the legend for the above figure, at the following link: https://lynceans.org/wp-content/uploads/2021/05/Chernobyl-Room-305_2-Assessment.pdf

Ukraine has long intended to remove the FCMs from the Unit 4 debris and store them in a geological repository. This plan remains under development, but now may have a new sense of urgency.

For more information

Richard Stone, “‘It’s like the embers in a barbecue pit.’ Nuclear reactions are smoldering again at Chernobyl,” ScienceMag, 5 May 2021: https://www.sciencemag.org/news/2021/05/nuclear-reactions-reawaken-chernobyl-reactor?utm_campaign=news_daily_2021-05-05&et_rid=215579562&et_cid=3762851
G.G. Pretzsch, et al., “The French-German Initiative for Chernobyl Sarcophagus Waste Management,” International Atomic Energy Agency, 2002: https://inis.iaea.org/collection/NCLCollectionStore/_Public/37/115/37115712.pdf?r=1&r=1
A.A. Borovov, et al., “Room 305/2 Block 4 of the Chernobyl NPP: Its Condition, Assessment of the Amount of Fuel,” Report INIS-UA- -062 (in Russian), International Atomic Energy Agency, 1998: Summary only: https://inis.iaea.org/search/search.aspx?orig_q=RN:32020405 and direct link to the complete report: https://inis.iaea.org/collection/NCLCollectionStore/_Public/32/020/32020405.pdf?r=1

The Next Phase in the Hunt for New Superheavy Elements is About to Start

February 3, 2019All Posts, Chemistry, Nuclear physics, PhysicsDC-280 cyclotron, Dimitri Mendeleev, Flerov Laboratory of Nuclear Reactions, FLNR, International Year of the Periodic Table of Chemical Elements, IYPT, Joint Institute for Nuclear Research, periodic table, Sergey Dmitriev, Superheavy Element Factory, Yuri OganessianDrummer

Peter Lobner

Background

On 24 January 2016, I posted the article, “Where in the Periodic Table Will We Put Element 119?”, which reviews the development of the modern periodic table of chemical elements since it was first formulated in 1869 by Russian chemist Dimitri Mendeleev, through the completion of Period 7 with the naming element 118 in 2016. You can read this post here:

https://lynceans.org/all-posts/where-in-the-periodic-table-will-we-put-element-119/

2019 is the 150^thanniversary of Dimitri Mendeleev’s periodic table of elements. To commemorate this anniversary, the United Nations General Assembly and the United Nations Educational, Scientific and Cultural organization (UNESCO) have proclaimed 2019 as the International Year of the Periodic Table of Chemical Elements (IYPT). You’ll find more information on the IYPT here:

https://www.iypt2019.org

A brief animated “visualization” entitled “Setting the Table,”created by J. Yeston, N. Desai and E. Wang, provides a good overview of the history and configuration of the periodic table. Check it out here:

http://vis.sciencemag.org/periodic-table/

The prospects for extending the periodic table beyond element 118 (into a new Period 8) is discussed in a short 2018 video from Science Magazine entitled “Where does the periodic table end?,”which you can view here:

https://www.sciencemag.org/news/2019/02/where-does-periodic-table-end?utm_campaign=news_weekly_2019-02-01&et_rid=215579562&et_cid=2632608

The next phase in the hunt for new superheavy elements is about to start in Russia

Flerov Laboratory of Nuclear Reactions (FLNR) Joint Institute for Nuclear Research (JINR) in Dubna is the leading laboratory in Russia, and perhaps the world, in the search for superheavy elements. The FLNR website is here:

http://flerovlab.jinr.ru/flnr/she_factory_no.html

FLNR is the home of several accelerators and other experimental setups for nuclear research, including the U400 accelerator, which has been the laboratory’s basic tool for the synthesis of new elements since being placed in operation in 1979. You can take a virtual tour of U400 on the FLNR website.

On 30 May 2012 the International Union of Pure and Applied Chemistry (IUPAC) honored the work done by FLNR when it approved the name Flerovium (Fl) for superheavy element 114.

Yuri Oganessian, the Scientific Leader of FLNR, has contributed greatly to extending the periodic table through the synthesis of new superheavy elements. On 30 November 2016, IUPAC recognized his personal contributions by naming superheavy element 118 after him: Oganesson (Og).

Yuri Oganessian. Source: MAX AGUILERA HELLWEG / WWW.SCIENCEMAG.ORG

2017 Armenian postage stamp honoring Yuri Oganessian. Source: FLNR JINR

FLNR has built a new $60 million accelerator facility, dubbed the Superheavy Element Factory (SHEF), which is expected to be capable of synthesizing elements beyond 118. The SHEF building and the DC-280 cyclotron that will be used to synthesize superheavy elements are shown in the photos below.

The SHEF building, 14 Nov 2016. Source: FLNR JINR

The completed DC-280 cyclotron, 26 December 2018. Source: FLNR JINR

The 2016 paper, “Status and perspectives of the Dubna superheavy element factory,”by S. Dmitriev, M. Itkis and Y. Oganessian, presents an overview of the DC-280 cyclotron design, including the following diagram showing the general arrangement of the major components.

Arrangement of the major components of the DC-280 cyclotron.

You can read this 2016 paper here:

http://inspirehep.net/record/1502737/files/epjconf-NS160-08001.pdf

For insights into the processes for synthesizing superheavy elements, I recommend that you view the following March 2018 video in which FLNR Director Sergey Dmitriev describes the design of SHEF and the planned process of synthesizing superheavy elements 119 and 120. This is a rather long (23 min) video, but I think it will be worth your time.

https://www.youtube.com/watch?v=5LIohLbjqyM

On 26 December 2018, the DC-280 cyclotron produced its first beam of accelerated heavy ions. The hunt for new superheavy elements using DC-280 is scheduled to begin in the spring of 2019.

A good overview of FLNR, as it prepares to put its Superheavy Element Factory into operation, is available in the article by Sam Kean, entitled “A storied Russian lab is trying to push the periodic table past its limits—and uncover exotic new elements,” which was posted on 30 January 2019 on the Science Magazine website. You’ll find this article at the following link:

https://www.sciencemag.org/news/2019/01/storied-russian-lab-trying-push-periodic-table-past-its-limits-and-uncover-exotic-new?utm_campaign=news_weekly_2019-02-01&et_rid=215579562&et_cid=2632608

The next few years may yield exciting new discoveries of the first members of Period 8 of the periodic table. I think Dimitri Mendeleev would be impressed.

Additional reading:

H. Kragh, “The Search for Superheavy Elements: Historical and Philosophical Perspectives,” Niels Bohr Institute https://arxiv.org/pdf/1708.04064.pdf

V. Utyonkov, et al., “The Discovery of Elements 113 – 118,” Nobel Symposium on the Chemistry and Physics of Heavy and Super Heavy Elements, 29 May – 3 June 2016 https://pls.llnl.gov/content/assets/docs/research-and-development/nuclear-science/NS160_final.pdf

M. Stoyer, “Super-Heavy Element and Other Exotic Nuclei Research at LLNL,” October 2015 https://www.researchgate.net/publication/270515886_Super-Heavy_Element_and_Other_Exotic_Nuclei_Research_at_LLNL

Y. Oganessian, “Discovery of the Island of Stability for Superheavy Elements,” Proceedings of IPAC2017 http://accelconf.web.cern.ch/AccelConf/ipac2017/papers/fryaa1.pdf

C. Moskowitz, “Superheavy Element 117 Points to Fabled ‘Island of Stability’ on Periodic Table,” Scientific American, 7 May 2014 https://www.scientificamerican.com/article/superheavy-element-117-island-of-stability/

“Extended Periodic Table,” Wikipedia https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Extended_periodic_table.html

Where in the Periodic Table Will We Put Element 119?

January 24, 2016All Posts, Chemistry, Nuclear physics, PhysicsAndreas von Antropoff, database of periodic tables, Dimitri Mendeleev, element 119, extended periodic table, Glenn Seaborg, International Union of Pure and Applied Chemistry, IUPAC, neutronium, Pekka Pyykkö, periodic table of elements, super actinidesDrummer

Peter Lobner

The first periodic table of elements

In 1869, Russian chemist Dimitri Mendeleev proposed the first modern periodic table of elements, in which he arranged the 60 known elements in order of their increasing atomic masses (average mass, considering relative abundance of isotopes in naturally-occurring elements), with elements organized into groups based their similar properties. Mendeleev observed that certain properties recur at regular intervals in the periodic table, thereby defining the groupings of elements.

Source: http://we-are-star-stuff.tumblr.com

This first version of the periodic table is compared to the modern periodic table in the following diagram prepared by SIPSAWIYA.COM. Mendeleev’s periodic table consisted of Groups I to VIII in the modern periodic table.

The gaps represent undiscovered elements predicted by Mendeleev’s periodic table, for example, Gallium (atomic mass 69.7) and Germanium (atomic mass 72.6) . You can read more about Mendeleev’s periodic table at the following link:

http://www.sipsawiya.com/2015/07/history-of-periodic-table.html

German chemist Lothar Meyer was competing with Mendeleev to publish the first periodic table. The general consensus is that Mendeleev, not Meyer, was the true inventor of the periodic table because of the accuracy and detail of Mendeleev’s work.

Element mendelevium (101) was named in honor of Dimitri Mendeleev.

Evolution of the Modern Periodic Table of Elements

The modern periodic table organizes elements according to their atomic numbers (number of protons in the nucleus) into 7 periods (vertical) and 18 groups (horizontal). The version shown below, in the International Union of Pure and Applied Chemistry (IUPAC) format, accounts for elements up to atomic number 118 and color-codes 10 different chemical series.

Source: http://sciencenotes.org/printable-periodic-table/

Hundreds of versions of the periodic table of elements have existed since Mendeleev’s first version. You can view a great many of these at The Internet Database of Periodic Tables curated by Dr. Mark R. Leach and presented at the following link:

http://www.meta-synthesis.com/webbook/35_pt/pt_database.php?Button=All

Glenn T. Seaborg (1912 – 1999) is well known for his role in defining the structure of the modern periodic table. His key contributions to periodic table structure include:

In 1944, Seaborg formulated the ‘actinide concept’ of heavy element electron structure, which predicted that the actinides, including the first 11 transuranium elements, would form a transition series analogous to the rare earth series of lanthanide elements. The actinide concept showed how the transuranium elements fit into the periodic table.
Between 1944 and 1958, Seaborg identified eight transuranium elements: americium (95), curium (96), berkelium (97), californium (98), einsteinium (99), fermium (100), mendelevium (101), and nobelium (102).

Element seaborgium (106) was named in honor of Glenn T. Seaborg. Check out details Glenn T. Seaborg’s work on transuranium elements at the following link:

http://www.osti.gov/accomplishments/seaborg.html

Four newly-discovered and verified elements

On 30 December 2015, IUPAC announced the verification of the discoveries of the following four new elements: 113, 115, 117 and 118.

Credit for the discovery of element 113 was given to a team of scientists from the Riken institute in Japan.
Credit for discovery of elements 115 , 117 and 118 was given to a Russian-American team of scientists at the Joint Institute for Nuclear Research in Dubna and Lawrence Livermore National Laboratory in California.

These four elements complete the 7^th period of the periodic table of elements. The current table is now full.

You can read this IUPAC announcement at the following link:

http://www.iupac.org/news/news-detail/article/discovery-and-assignment-of-elements-with-atomic-numbers-113-115-117-and-118.html

On 28 November 2016, the IUPAC approved the names and symbols for these four new elements: nihonium (Nh), moscovium (Mc), tennessine (Ts), and oganesson (Og), respectively for element 113, 115, 117, and 118. Nihonium was the first element named in Asia.

Dealing with super-heavy elements beyond element 118

The number of physically possible elements is unknown.

In 1969, Glenn T. Seaborg proposed the following extended periodic table to account for undiscovered elements from atomic number 110 to 173, including the “super-actinide” series of elements (atomic numbers 121 to 155).

Source: W. Nebergal, et al., General Chemistry, 4^th ed., pp 668 – 670, D.C. heath Co, Massachusetts, 1972

In 2010, Finnish chemist Pekka Pyykkö at the University of Helsinki proposed an extended periodic table with 54 predicted elements. The extension, shown below, is based on a computational model that predicts the order in which the electron orbital shells will fill up, and, therefore, the periodic table positions of elements up to atomic number 172. Pekka Pyykkö says that the value of the work is in showing, “how the rules of quantum mechanics and relativity function in determining chemical properties.”

Source: Royal Society of Chemistry

You can read more on Pekka Pyykkö’s extended periodic table at the following link:

http://www.rsc.org/Publishing/ChemScience/Volume/2010/11/Extended_elements.asp

You can read more general information on the extended periodic table on Wikipedia at the following link:

https://en.wikipedia.org/wiki/Extended_periodic_table

So where will we place element 119 in the periodic table of elements?

Based on both the Seaborg and Pyykkö extended periodic tables described above, element 119 will be the start of period 8 and it will be an alkali metal. Element 120 will be an alkaline earth. With element 121, we’ll enter the new chemical series of the “super-actinides”.

These are exciting times for scientists attempting to discover new super-heavy elements.

Where does neutronium fit in the periodic table?

Neutronium is a name coined in 1926 by scientist Andreas von Antropoff for a proposed “element of atomic number zero” (i.e., because it has no protons) that he placed at the head of the periodic table. In modern usage, the extremely dense core of a neutron star is referred to as “degenerate neutronium”.

Neutronium also finds many hypothetical applications in modern science fiction. For example, in the 1967 Star Trek episode, The Doomsday Machine, neutronium formed the hull of a giant, autonomous “planet killer”, and was portrayed as being invulnerable to all manner of scans and weapons. Since free neutrons at standard temperature and pressure undergo β– decay with a half-life of 10 minutes, 11 seconds, a very small quantity of neutronium could be quite hazardous to your health.

14 January 2019 Update: 2019 marks the 150th anniversary of Dimitri Mendeleev’s periodic table

You’ll find a very good article, “150 years on, the periodic table has more stories than it has elements,” by Elizabeth Quill on the Science News website. Here’s the link:

https://www.sciencenews.org/article/periodic-table-elements-chemistry-fun-facts-history

18 January 2019 Update: Possibly the oldest copy of Mendeleev’s periodic table was found at the University of St. Andrews in Scotland

On 17 January 2019, the University of St. Andrews posted a news article stating that a periodic table of the elements dating from 1885 recently was found at the university and is thought to be the oldest in the world.

The 1885 periodic table. Source: University of St. Andrews

You can read the University of St. Andrews news posting here:

https://news.st-andrews.ac.uk/archive/worlds-oldest-periodic-table-chart-found-in-st-andrews/