Zirconium

Metals -> Metals, Inorganic Compounds

Flammable agents - 4th degree

6.51 (Metal) (NIOSH, 2024) - Denser than water; will sink

6.51 (Metal) (NIOSH, 2024) - Denser than water; will sink

6.51 (Metal) (NIOSH, 2024) - Denser than water; will sink

6.51 (Metal) (NIOSH, 2024) - Denser than water; will sink

6.52 g/cu cm

Relative density (water = 1): 6.5

Bluish-black, amorphous powder or grayish-white lustrous metal (platelets or flakes) of hexagonal lattice below 865 °C; body-centered cubic above 865 °C

Grey-white metal; hexagonal

Soft, malleable, ductile solid or gray to gold, amorphous powder

Insoluble (NIOSH, 2024)

Insoluble (NIOSH, 2024)

Insoluble (NIOSH, 2024)

Insoluble (NIOSH, 2024)

Soluble in hot concentrated acid

Solubility in water: none

6471 °F at 760 mmHg (NIOSH, 2024)

6471 °F at 760 mmHg (NIOSH, 2024)

6471 °F at 760 mmHg (NIOSH, 2024)

6471 °F at 760 mmHg (NIOSH, 2024)

4406 °C

3577 °C

3375 °F (NIOSH, 2024)

3375 °F (NIOSH, 2024)

3375 °F (NIOSH, 2024)

3375 °F (NIOSH, 2024)

1854 °C

1857 °C

0 mmHg (approx) (NIOSH, 2024)

0 mmHg (approx) (NIOSH, 2024)

0 mmHg (approx) (NIOSH, 2024)

0 mmHg (approx) (NIOSH, 2024)

Approximately 0 mm Hg

0 mmHg (approx)

Zirconium powder wet appears as a gray amorphous sludge with not less than 25% water.

Zirconium powder, dry appears as a gray amorphous powder. May ignite spontaneously and burn with explosive violence. Ignitable by static electricity. Small amounts of moisture may promote the ignition of zirconium. Continues to burn despite immersion in water and does so with greater intensity than in air. Used to make corrosion-resistant alloys, in pyrotechnics, and for many other uses.

Zirconium scrap appears as a lustrous, grayish metallic solid. May ignite spontaneously and burn with explosive violence. May ignite by static electricity. Burns immersed in water and does so with greater intensity than if burned in air.

Powdered or finely divided metal suspended in a flammable organic solvent. Dry powder left after the evaporation of the solvent is easily ignited. Static electricity may be sufficient to ignite the powder.

Zirconium, dry, coiled wire, finished metal sheets or strips appears as a grayish-white hard lustrous metal. Specific gravity 6.4. Melting point about 3362 °F (1850 °C). Insoluble in water. Low toxicity.

Hard lustrous grayish crystalline scales or gray amorphous powder.

Danger

H250: Catches fire spontaneously if exposed to air [Danger Pyrophoric liquids]

P210, P222, P223, P231, P231+P232, P233, P280, P302+P335+P334, P370+P378, P402+P404, and P501 (click each P-code to see the statement)

This chemical does not meet GHS hazard criteria for 4.7% (20 of 422) of reports.

Danger

H250 (43.8%): Catches fire spontaneously if exposed to air [Danger Pyrophoric liquids]

Chemical: Zirconium

Zirconium is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Zirconium are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

Status: Active Update: 11-10-2022 https://echa.europa.eu/registration-dossier/-/registered-dossier/13595

Zirconium: Does not have an individual approval but may be used under an appropriate group standard

The New Jersey Worker and Community Right to Know Act requires public and private employers to provide information about hazardous substances at their workplaces. (N.J.S.A. 34:5A-1 et. seq.)

Flammable Solid

Spontaneously Combustible

Spontaneously Combustible

Flammable Liquid

Flammable Solid

Spontaneously Combustible

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Zirconium metal dust dispersed with uranium and uranium hydride as a cloud ignites under certain conditions.

Clean zirconium plate ingnites spontaneously in oxygen of about 2 MPa (300 psi); the autoignition pressure drops as the metal thinckness decreases.

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Other than the skin and respiratory irritant effects of zirconium chloride, work-related diseases caused by zirconium have not been documented. [ACGIH] Zirconium compounds, both soluble and insoluble, have the following notation, Danger of sensitization of the airways and the skin. [MAK] Repeated inhalation of zirconium tetrachloride mist by dogs for 2 months at 6 mg/m3 as zirconium caused slight decreases in hemoglobin and in erythrocyte counts, with some increases in mortality over that of controls; these effects may have been due to the liberation of hydrogen chloride. [NIOSH Guidelines for Chemical Hazards] Generally considered to be of low toxicity. Zirconium chloride (ZrCl4) can cause acute pneumonitis. No lung changes were found in 32 workers with 1-17 years of exposure to zirconium metal reactor parts. A lens grinder who mixed zirconium oxide powder and polished optical lenses developed interstitial fibrosis after a latency of 15 years. [Harber, p. 479, 487, 506] Soluble zirconium compounds include nitrates, acetates, sulfates, chlorides, bromides, iodides, and salts of Na, K, and ammonium; Insoluble zirconium compounds include hydroxides, carbonates, and phosphates; [Nordberg, p. 19]

1358 170

2008 135

1932 135

2009 135

1358 170(powder, wet)

1932 135(scrap)

Metals, Elemental and Powder, Active

Metals, Elemental and Powder, Active

Metals, Elemental and Powder, Active

Metals, Elemental and Powder, Active

Metals, Elemental and Powder, Active

Metals, Elemental and Powder, Active

Anon; Zirconium Powder; National Safety Council (1986). This data sheet identifies the hazards related to the use, handling and storage of zirconium powder (pyrophoric) and describes safe practices for preventing accidents.

USNRC; Backgrounder Report of Three Mile Island Accident (February 2013) /Three Mile Island Accident/[USNRC; Backgrounder Report of Three Mile Island Accident (February 2013). Available from, as of April 16, 2015: http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.pdf]

The National Diet of Japan; Fukushima Nuclear Accident Independent Investigation Commission[The National Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission Main Report. Available from, as of April 16, 2015: http://warp.da.ndl.go.jp/info:ndljp/pid/3856371/naiic.go.jp/en/]

Bartter T et al; Zirconium-Induced Pulmonary Fibrosis Annual Meeting of the American Lung Association and the American Thoracic Society, Cincinnati, Ohio 5/14-5/17 1989. Results of a symposia concerned with the health effects resulting from zirconium exposure.

USEPA; Development Document for Effluent Limitations, Guidelines, & Standards for the Nonferrous Metals Manufacturing Point Source Category. Vol 9 Primary & Secondary Titanium, Primary Zirconium & Hafnium; GRA & I Issue 11 (1990) EPA 440/1-89/019.9

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Fresh air, rest.

Remove contaminated clothes. Rinse and then wash skin with water and soap.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth.

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from NIOSH Pocket Guide for Zirconium compounds (as Zr):

Excerpt from NIOSH Pocket Guide for Zirconium compounds (as Zr):

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from NIOSH Pocket Guide for Zirconium compounds (as Zr):

Excerpt from NIOSH Pocket Guide for Zirconium compounds (as Zr):

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Wear positive pressure self-contained breathing apparatus (SCBA).

1.0 [mg/m3], inhalable fraction (elemental)[German Research Foundation (DFG)]

Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary.

Fires ... require quenching by smothering with ... pulverized mineral carbonate such as dolomite.

To fight fire use special mixtures, dry chemical, salt or dry sand.

If material on fire or involved in fire: Do not use water; Use dry chemical, graphite, or dry earth; When fire is out, cover all suspected material with dry sand or earth to prevent re-ignition until material can be permanently disposed of; Keep run-off water out of sewers and water sources. /Zirconium, dry, spontaneously combustible/

For more Fire Fighting Procedures (Complete) data for ZIRCONIUM, ELEMENTAL (9 total), please visit the HSDB record page.

Accidental release measures: Personal precautions, protective equipment and emergency procedures: Avoid dust formation. Avoid breathing vapors, mist or gas. Environmental precautions: No special environmental precautions required. Methods and materials for containment and cleaning up: Sweep up and shovel. Keep in suitable, closed containers for disposal.

Sweep spilled substance into containers; if appropriate, moisten first to prevent dusting. Carefully collect remainder, then remove to safe place. Personal protection: P2 filter respirator for harmful particles.

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 170 [Metals (Powders, Dusts, Shavings, Borings, Turnings, or Cuttings, etc.)]:

Excerpt from ERG Guide 135 [Substances - Spontaneously Combustible]:

Product: Offer surplus and non-recyclable solutions to a licensed disposal company. Contaminated packaging: Dispose of as unused product.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

SRP: Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.

IDENTIFICATION AND USE: Zirconium is a grey-white metal. Zirconium, elemental is used in varying forms; dust, foil and chopped machining chips. It is used as an ingredient of priming or explosive mixtures; flashlight powders; as deoxidizer in metallurgy; as "getter" in vacuum tubes; in constructing rayon spinnerets in lamp filaments, flash bulbs, and nuclear reactors. Pure zirconium is being increasingly used as a corrosion-resistant metal in fabricating columns, pumps, pipe, valves, heat exchangers, and tanks for severe chemical environments, particularly sulfuric and hydrochloric acids, except those containing fluorides. In this capacity, it is also used in facilities producing urea, hydrogen peroxide, methyl methacrylate, or acetic acid. HUMAN EXPOSURE AND TOXICITY: A study of 22 workers exposed to fumes during the zirconium reduction process for 1 to 5 years revealed no striking abnormalities referable to zirconium exposure. Also, 32 male hand finishers of zirconium metal reactor components who had worked for 1 to 17 years in that job showed no significant differences from the control group. Pulmonary granuloma in zirconium workers have been reported; however, the reports do not specify whether it was due to zirconium metal or a specific compound of zirconium. In addition, dermal granulomatous lesions, probably of allergic epithelioid origin, have been observed following the use of deodorant sticks and poison ivy lotions containing zirconium; the latter chemical may have been used as a compound and not as the metal per se. ANIMAL STUDIES: No animal toxicity studies were found at time of review.

Redness. Pain.

Skin, lung granulomas; In Animals: irritation skin, mucous membrane; X-ray evidence of retention in lungs

/SIGNS AND SYMPTOMS/ /Causes/ pain and redness /in/ eyes.

/CASE REPORTS/ A study of 22 workers exposed to fumes during the zirconium reduction process for 1 to 5 years revealed no striking abnormalities referable to zirconium exposure. Also, 32 male hand finishers of zirconium metal reactor components who had worked for 1 to 17 years in that job showed no significant differences from the control group.

/OTHER TOXICITY INFORMATION/ Pulmonary granuloma in zirconium workers have been reported; however, the reports do not specify whether it was due to zirconium metal or a specific compound of zirconium. In addition, dermal granulomatous lesions, probably of allergic epithelioid origin, have been observed following the use of deodorant sticks and poison ivy lotions containing zirconium; the latter chemical may have been used as a compound and not as the metal per se.

The use and production of zirconium in the aviation, aerospace, chemical and surgical instrument industries, and in nuclear reactor technology(1) may result in the release of zirconium to the environment through various waste streams(SRC).

Of the many radionuclides produced in nuclear and thermonuclear explosions, the primary contributors to exposure of humans are ... Zirconium-95 ... . /Zirconium-95/

According to the 2012 TSCA Inventory Update Reporting data, 4 reporting facilities estimate the number of persons reasonably likely to be exposed in manufacturing, processing, or use of zirconium in the United States may be as low as <10 workers and as high as 999 workers per plant; the data may be greatly underestimated due to confidential business information (CBI) or unknown values(1).

Zirconium is a common element present in the earth's crust and is found in concentrations ranging from 150 to 300 mg/kg. It is not found in the elemental state but usually as oxides. Zirconium occurs in the minerals zircon, malacon, baddeleyite, zirkelite, eudialyte. It is also found frequently in the rare-earth minerals and in monazite sand. Zirconium in found in S-type stars and has been identified in the sun and meteorites. Lunar rocks were found to contain high concentrations of zirconium oxide as compared with terrestrial rocks. The use and production of zirconium metal in the aviation, aerospace, chemical and surgical instrument industries, and in nuclear reactor technology may result in the release of zirconium to the environment through various waste streams. In general, metal cations in solution are attracted to the negatively charged surfaces of soil particles. The extent of adsorption of metal ions to soils depends on the pH, the mineral content, and organic content of the soil. (SRC)

There are only a few situations in which water should not be used for skin decontamination. ... The dusts of pure... zirconium will ignite or explode when contacted by water. Thus, following exposure..., any residual metal should be removed with forceps, gauze, or towels, and stored in mineral oil.

Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Poisons A and B/

Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poisons A and B/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W TKO /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam (Valium) or lorazepam (Ativan) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poisons A and B/

8e-05

SCREEN Current

8e-05

PPRTV Current

The metal is used in nuclear energy technology, photoflash bulbs, vacuum tubes, and steel manufacturing (as a scavenger). Zirconium oxide is used in ceramic colorants, metal hardening (platinum and ruthenium), and as a radiopaque material for diagnostic x-rays. Zirconium chloride is used in textiles (water repellant) and tanning. Zircon is a natural zirconium silicate used to make refractories and other ceramics. It is also used as an abrasive. Water soluble zirconium compounds are used in cosmetics. [ACGIH]

Steel Producing [Category: Industry]

... Used in the development of reserve batteries; the heat pellet used in the activation of these batteries is usually a mixture of zirconium and an oxidant such as potassium perchlorate. Such batteries have been manufactured for military ordinance for use in rockets, bombs, missiles, etc.

... Catalyst in organic reactions.

Used as reflective surface agent on satellites; in alloys to be used in noncorrosive chemical apparatus... Powder alloyed with lead used in cigarette lighter flints.

... metal-to-glass seals; special welding fluxes; ... laboratory crucibles; spinnerettes.

Commercial-grade ... contains from 1 to 3% hafnium.

Iron, chromium, tin, niobium, and hafnium.

(1985) 7.26X10+9 g

(2000) 243 metric tons /Zirconium, alloys, waste and scrap, and powder (ZrO2 content)

(2001) 251 metric tons /Zirconium, alloys, waste and scrap, and powder (ZrO2 content)

(2002) 281 metric tons /Zirconium, alloys, waste and scrap, and powder (ZrO2 content)

For more U.S. Exports (Complete) data for ZIRCONIUM, ELEMENTAL (12 total), please visit the HSDB record page.

(1985) 4.54X10+9 g

(2000) 1,400 metric tons /Zirconium, alloys, waste and scrap, and powder (ZrO2 content)

(2001) 850 metric tons /Zirconium, alloys, waste and scrap, and powder (ZrO2 content)

(2002) 750 metric tons /Zirconium, alloys, waste and scrap, and powder (ZrO2 content)

For more U.S. Imports (Complete) data for ZIRCONIUM, ELEMENTAL (12 total), please visit the HSDB record page.

2023: 7,000,000 - <8,500,000 lb

Production volume for non-confidential chemicals reported under the 2006 Inventory Update Rule. Chemical: Zirconium. Aggregated National Production Volume: 1 to < 10 million pounds.

Non-confidential 2012 Chemical Data Reporting (CDR) information on the production and use of chemicals manufactured or imported into the United States. Chemical: Zirconium. National Production Volume: 9,129,250 lb/yr.

Consumption of ... sponge is mainly for military purposes; substantial amounts find use in private power reactors; almost 50 tons were used in industry unrelated to nuclear power (ie, photographic flash bulbs).

Foundry sands, 47%; Refractories, 22%; Ceramics, 10%; Abrasives, 6%; and misc, 15% (1985).

Ductile zirconium metal is produced by reduction of pure zirconium tetrachloride with molten magnesium under an inert gas (helium or argon).

Ductile, pure zirconium is made by a two-stage sodium reduction of zirconium tetrachloride in which the tetrachloride and sodium are continuously fed into a stirred reactor to form zirconium dichloride; heating with additional sodium yields zirconium metal. Leaching with water removes the sodium chloride from the zirconium. Bomb reduction of pure zirconium tetrafluoride with calcium also produces pure metal.

In van Arkel-de Boer process, crude ... metal ... is heated /in/ vessel containing iodide ... at relatively low temperature ... to form volatile iodides of zirconium, which are thermolyzed ... at about 1300 °C with deposition of ... metal ... /and/ recovered as bright, extremely pure metal crystals.

Fluidized-bed carbochlorination of milled zircon sand is the zircon decomposition process used by American and French zirconium metal producers. Chlorine is the fluidizing gas. The reaction is endothermic and supplemental energy is supplied, usually by induction heating of the interior graphite wall of the chlorinator.

Zirconium and hafnium are chemically and metallurgically very similar, and for most uses of zirconium their separation is unnecessary. Their separation is conducted only to produce hafnium-free zirconium metal for the nuclear power industry. Of the many methods developed since the discovery of hafnium, four are used industrially: fluoride salt crystallization, methyl isobutyl ketone extraction, tributyl phosphate extraction, and extractive distillation, in order of their development. In addition, ion exchange has been used for low-throughput, low-investment operations.

Plate, strip, bars, wire; sponge and briquettes; powder; foil; technical; pure (hafnium-free); single crystals.

Zirconium metal is marketed in three forms: zirconium-containing silicon-manganese, iron, ferrosilicon, or magnesium master alloys; commercially pure zirconium metal; and hafnium-free pure zirconium metal.

/Available in/ six grades from 3-6 mm to type 2-5 microns, 96 to 99.8% purity grades.

Utilities

Zirconium: ACTIVE

Zirconium is ... abundant metal in the earth's crust, with an estimated concentration of 0.016-0.025 wt%, about one twentieth that of titanium but more plentiful than nickel, copper, or zinc. Zirconium occurs only in fully oxidized form, never as free metal.

Naturally occurring zirconium contains five isotopes. Thirty-one other radioactive isotopes and isomers are known to exist.