Den här skrivelsen är skickad till den amerikanska motsvarigheten till SKI (Kärnkraftsinspektionen) av en miljöaktivistgrupp. Det framgår bl a att kärnkraftverk behöver ström utifrån för att fungera. Om ett avbrott sker i den externa strömförsörjningen, SAMTIDIGT som kärnkraftverket självt driftstoppas (t ex av en y2k-relaterad händelse) börjar reaktorn att stänga av sig själv. Men reaktorhärden kommer då inte att kylas korrekt. Det tar sex månader för en reaktorhärd att kylas av för att den ska vara säker från att inte uppnå kritisk massa av sig självt (och utlösa en härdsmälta). Med andra ord, för att kärnkraftverken skall vara HELT SÄKRA 1 januari år 2000 bör samtliga reaktorer stängas av redan vid halvårsskiftet under 1999.

NUCLEAR POWER AND Y2K

In mid-1998, a nuclear utility in Sweden decided to see what would happen if it switched the clocks in its reactor’s computers to read January 1, 1999. The response surprised utility officials, who had expected business as usual. The reactor’s computers couldn’t recognize the date (1/1/99) and thus turned the reactor off. If the utility had waited to run this test, New Year’s Eve would have been rather cold in Sweden. The Y2K computer bug caused the problem. The Y2K computer bug has the potential to affect the safety and operation of commercial nuclear power reactors, other major nuclear facilities, and the entire electrical power grid. This is true in the U.S. and abroad. While utilities are working to correct their Y2K vulnerabilities, it is not clear that all such problems will be fixed in time. Citizens can play an important role in ensuring that any Y2K-related disruptions are minimized by encouraging their utilities, state and local governments, and federal regulators and officials to devote the resources necessary to address the issue and to make appropriate contingency and emergency plans to cope with unexpected circumstances.

BACKGROUND

The Y2K computer bug stems from the early days of computers, when memory was very expensive. Software designers saved on memory costs by writing date-sensitive functions with a two-digit year (i.e. 98 instead of 1998). Thus, when the program reaches the year 2000, it may read it as 1900, with unpredictable ramifications. Many of these early programmers assumed their programs would be obsolete by 2000. Unfortunately, the practice continued for many years, and affects not only the early mainframe computers, but also personal computers and other electronic devices that use preprogrammed "embedded chips." In addition, depending on how programs were written, other dates may set off problems, including January 1, 1999, September 9, 1999, February 29, 2000, and others.

Y2K AND NUCLEAR SAFETY

The federal Nuclear Regulatory Commission and the nuclear power industry, through its trade association Nuclear Energy Institute (NEI), claim that the Y2K bug does not affect the safety of atomic reactors. This attitude, while reassuring, may be overly optimistic. For example, an NRC audit of the Seabrook reactor in New Hampshire, released November 6, 1998, found, in this single power plant, 1,304 separate software items and embedded chips that were affected by the Y2K bug. Twelve of these were described as having "safety implications," including the critical Reactor Vessel Level Indication System; another 13 could cause the reactor to trip (itself a potential safety issue); 160 affected systems required by regulations; and 800 were "significant to business"—in other words, keeping the supply of electricity from the plant running. Only about 40% of the items were described as having "minimal" or "no impact" on plant operations. The NRC plans to conduct audits of only 12 reactor sites (out of more than 70) and, by December 1, 1998, had completed and published only three of these. All showed some potential compromise of safety-related systems. In addition, the unpredictable nature of computer and embedded chip responses to an unreadable date means that some failures of systems not directly related to safety could adversely affect safety systems or operator responses to unrelated emergencies (e.g., by providing incorrect data).

REACTORS NEED ELECTRICITY

The Y2K bug threatens to disrupt the electrical grid, and could cause local or regional blackouts. Some have predicted a national electrical blackout. Consider that there are more than 1,000 different utilities, public and private, and non-utility generators of electricity in the U.S. and Canada. In June 1998, a U.S. Senate Committee issued a survey of the ten largest U.S. utilities. The Committee concluded that "there is significant cause for concern" about utilities efforts to remedy the Y2K problem, that "assurances of timely Y2K compliance [are] little more than a hope," and that, because the utilities surveyed are the largest in the nation, "we are pessimistic about the implications for the rest of the utility sector." Failure of some small utilities could cause instability in the electrical grid, leading to localized blackouts; failure of one or more larger utilities could lead to regional blackouts. While this would be inconvenient at best for most people, it is potentially disastrous for nuclear reactors. A little-known reality of nuclear power is that atomic reactors need a steady source of electricity to cool their cores and irradiated fuel pools even when they are shut down. Without this cooling ability, even closed reactors would melt down; fuel pools would boil dry and release their highly-radioactive inventories. The Nuclear Regulatory Commission considers this "station blackout" scenario to be among the largest contributors to risk of operating reactors. To compensate, nuclear plants are required to have back-up power sources. These are normally giant generators that run on diesel oil and each reactor is required to have two of them (although some multi-reactor sites share generators). But these diesel generators can be unreliable. At best, the NRC says they are 95% reliable. That means that if all 200 or so generators were required at one time, 10 may fail. Moreover, there is reason to believe, given the operating history of these generators, that the 95% level is little more than wishful thinking.

WE’VE GOT EMERGENCY PLANS, OR DO WE?

Nuclear utilities have been slow to design and implement contingency plans to cope with unforeseen Y2K-related problems. The Senate Committee found, in June 1998, that "none of the utilities surveyed had completed contingency plans…" For the most part, contingency plans will be folded into existing emergency response plans at nuclear utilities. But these emergency plans, which include emergency evacuation capabilities, are tested only once every two years, meaning that under current regulations, at least half the utilities will never even test their Y2K-related plans. All nuclear emergency plans rely heavily on off-site sources of assistance, including police, fire and other essential services. But these services, as well as critical communications abilities, also may be vulnerable to the Y2K bug if not properly assessed, remedied and tested.

THE INDUSTRY RESPONSE TO Y2K

The utility industry, including the nuclear utilities and the NRC, has been working to resolve Y2K issues. For the most part, they say they will be "Y2K ready" (which does not necessarily mean compliant) by the turn of the millennium. But many utilities began working on the problem late, and some have not even completed their initial assessments of the scope of their problems. Once the assessments are completed, utilities must repair the problems, if possible, or purchase and install new systems. Then systems must be tested, itself a time-consuming process that may reveal still more bugs and incompatibilities. Few utilities have allowed themselves more than a few months to fully test all systems and repair any new problems found.

WHAT YOU CAN DO

Citizens can take several proactive steps to help assure that Y2K-related disruptions will be minimized and that effective emergency and contingency plans are implemented. In December 1998, the Nuclear Information and Resource Service (NIRS) submitted three emergency petitions for rulemaking to the NRC. These call for: the shutdown of all reactors that are not demonstrably Y2K compliant through full testing, by December 1, 1999 until they are compliant; installation of additional sources of back-up power to replace or supplement the existing diesel generators. These may include solar, wind, natural gas, hydro or other dedicated power systems; a requirement that every nuclear utility test a full-scale emergency plan during 1999 with a scenario that includes a Y2K-related component. Concerned people should write to the NRC (U.S. NRC, Washington, DC 20555, Attn: Docketing and Service Branch) in support of these petitions. Copies of the petitions are available from NIRS. People can also contact your state and local officials and urge them to institute separate emergency and contingency plans for your state, paying special attention to the possibility of electrical blackouts and telecommunications failures.

Finally, people should contact their federal legislators and demand continued congressional hearings on the nuclear industry and Y2K, and ask their Congressmembers to support the NIRS petitions. The Y2K issue is, by its very nature, rapidly changing. New information continually is being developed. For the latest information, check the NIRS website (http://www.nirs.org) or contact NIRS.

Michael Mariotte, December 1998

Källa: Nirs