Washington — From satchel charges carried by a single commando to nine-megaton behemoths that make Hiroshima look like a firecracker, the United States nuclear arsenal is growing steadily and becoming an increasingly important part of a ''nuclearized'' military service.
There are now 26,000 nuclear weapons in the US inventory, only half of which are addressed in the stalled strategic and intermediate-range nuclear arms talks. With the current modernization program begun by former President Carter but accelerated by President Reagan, this arsenal will grow steadily over the next decade to more than 30,000 weapons, and just about the whole lot will be replaced by newer varieties with greater range, accuracy, and explosive power.
Eight warhead types are in production and at least 16 more are in research and development, according to a three-year study of government and technical data by the Natural Resources Defense Council (NRDC). On average, eight new warheads are produced every working day, while five are retired. The Defense and Energy Departments say it is ''not in the national interest'' to publish such material, but do not dispute the NRDC findings released this week.
A follow-up report on the Soviet nuclear arsenal is scheduled, but other sources confirm that Moscow is steadily building up its atomic stockpile as well. NATO officials this week said the Soviet Union had deployed another nine SS-20 three-warhead missiles since Moscow left the intermediate-range nuclear force negotiations in Geneva late last year, bringing the total to 378 SS-20s. US officials also are particularly worried about the new varieties of Soviet cruise missiles, which are easy to hide.
The Reagan administration says it's serious about arms control and Moscow this week tried to indicate the same by proposing a ban on chemical weapons in Europe. But while politicians in Washington and the Kremlin ponder, the numbers and types of nuclear weaponry continue to grow.
Some feel that as long as the East-West nuclear arsenal is in rough balance, war is deterred.
''As our modernization plans are realized,'' states the Defense Department's annual report to Congress for 1984, ''Our retaliatory posture, on which the credibility of our deterrent depends, will continue to be strong.''
But writing in the current issue of Foreign Affairs magazine, one expert cautions that the ''larger number of weapons . . . also increases the risk of war through accident, terrorist theft, or official lunacy.''
More important, asserts Alton Frye, Washington director of the Council on Foreign Relations, ''Expanding force levels generate pressures to compensate for new-felt insecurity by adopting reckless policies, e.g., launch-on-warning, and by structuring forces in ways which improve survivability at the cost of the verifiability necessary to reassure the parties that neither intends to use the weapons it deploys.''
This has been a big week for reports and books on US nuclear capability. In addition to the NRDC report, there is a new book on ballistic missile defenses by the Brookings Institution, a technical primer on nuclear weapons by Massachusetts Institute of Technology expert Kosta Tsipis, and a detailed study of the US nuclear weapons industry. These, plus the others that have come out in recent months, indicate the growing public interest in having more than ''The Day After'' type TV sensationalism on which to base opinion.
US officials remind critics that the NATO allies in recent years have actually reduced the thousands of so-called ''battlefield'' nuclear weapons deployed in Europe and plan to remove even more. At the same time, however, the Reagan administration is pushing for new types of nuclear artillery shells including enhanced radiation (neutron) weapons.
Among the other next-generation US nuclear weapons cited in the NRDC ''Nuclear Weapons Databook'' are:
* Maneuvering reentry vehicles (MaRVs), missile warheads that can sense their position relative to the target and make close-in course corrections.
* Advanced strategic air-launched cruise missiles that can travel at four times the speed of sound, maneuver at this high speed, and evade enemy defenses.
* Third-generation directed energy weapons, including X-ray lasers and electromagnetic impulse weapons to destroy an enemy's command and control facilities.
* Tactical air-to-surface bombs that can be released at a safe distance from the target and will maneuver to it. One of these is known as the TIGER (terminal guided and extended range missile).
The US has more than twice as many strategic missile warheads at sea (about 5 ,000) as it has land-based ICBMs (2,100). And the sea-based nuclear force continues to grow.
The newer Trident submarines are entering the fleet at the rate of about one a year, and each can carry 24 missiles with a total of 192 warheads.
''About half of the ships in the Navy today are nuclear certified,'' said William Arkin, director of nuclear weapons research at the Institute for Policy Studies and an NRDC study author. ''The land-attack role will be significantly augmented with the deployment of the first of 758 long-range SLCMs (sea-launched cruise missiles) this summer.''
''The United States is now accelerating the introduction of new weapons into the nuclear stockpile . . . in the biggest production program since the early days of the nuclear era,'' said Milton Hoenig, a physicist and former US Arms Control and Disarmament Agency official who is another of the authors of the NRDC study.
''The nuclearization of the US armed forces extends far beyond what is known by the public, particularly in the case of weapons for tactical purposes,'' Dr. Hoenig said this week. ''The nuclear certified units (more than 700 units totaling some 100,000 troops) extend into the Marine Corps, the National Guard and Reserves, and numerous allied countries.''