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Davis Besse update from ANS
Bill Corcoran wrote:
> UPDATED COST AND SCHEDULE ESTIMATES FOR DAVIS-BESSE were released on
> October 7 by the plant's operator, FirstEnergy Nuclear Operating
> Company
> (FENOC). The estimates, related to replacement work for the plant's
> degraded vessel head, remain "unchanged" from earlier cost figures of
> $55
> million to $75 million, according to FENOC. The cost for restoration
> work,
> however, is skyrocketing. Initially estimated at $50 million to $70
> million, this work, which FENOC said would "enhance the reliability
> and
> performance of plant equipment," now is expected to cost an additional
> $115
> million. Of the added cost, $65 million will be spent by year end,
> with the
> remaining $50 million to be incurred next year. Much of the $50
> million
> should be spent after the plant returns to service, which FENOC has
> pegged
> for the first quarter of 2003. The restoration work will include what
> FENOC
> called "extent of condition" projects, notably redesigning and
> rebuilding
> the containment sump, expanding work on air coolers, and a more
> extensive
> recoating of equipment and structures. The additional funds also will
> go
> toward "accelerated maintenance activities," FENOC said, such as
> reactor
> coolant pump work, cooling tower basin repairs, and valve maintenance.
>
> FENOC earlier had hoped to get the plant back on line by the end of
> the
> year, but, according to the company, the latest change in schedule "is
>
> designed to further ensure that related work is completed in
> accordance
> with all applicable requirements, with the continued understanding
> that
> restart is subject to NRC review and approval."
> Davis-Besse, an 873-MWe (net) Babcock & Wilcox pressurized water
> reactor
> located in Oak Harbor, Ohio, has been shut down since February when
> the
> plant started a refueling outage. During the outage, severe
> degradation of
> the vessel head was discovered in March. FENOC has purchased a
> replacement
> head from the discontinued Midland nuclear power plant in Michigan,
> and is
> in the process of installing the replacement head. FENOC noted that
> "structure work to support replacement of the reactor head has been
> completed, all significant modifications are progressing on schedule,
> and
> all major work is expected to be finished by year-end."
> FENOC has spent $20 million per month in July and August to buy
> replacement power, and another $10 million to $15 million per month
> for
> nonsummer months.
> * With repairs under way to replace the degraded vessel head at
> Davis-Besse, rust stains and what appeared to be boric acid deposits
> were
> found in mid-October on the exterior bottom of the vessel. FENOC was
> performing tests to identify the source of the stains. Viktoria
> Mitlyng,
> NRC spokesperson, said on October 21 that the stains, found near
> lower-vessel nozzle penetrations, are probably the result of one of
> two
> scenarios. Most likely, she said, the stains were caused by "wash down
> of
> boric acid from the top of the reactor during cleaning." A second,
> less likely possibility, she said, is that the stains were caused by
> "leakage
> from the bottom nozzles that are smaller but similar to the nozzles on
> the
> top" of the reactor. Fifty-two nozzles penetrate the bottom of the
> vessel,
> carrying instrumentation into the base of the vessel. This was the
> first
> time that FENOC workers had inspected the vessel bottom because it was
>
> covered with insulation prior to the inspection. Mitlyng said that
> FENOC
> was performing chemical analysis of the rust stains, and the NRC was
> waiting to see results of those tests before any regulatory action was
>
> taken. FENOC was expected to have test results during the week of
> October
> 21, according to Mitlyng.
> * The NRC on October 9 issued a 96-page "lessons learned" report
> looking
> into the agency's handling of the Davis-Besse vessel head degradation.
> The
> report, prepared by an NRC task force, concluded that while the
> degradation
> was preventable, it was allowed to occur because the NRC, Davis-Besse,
> and
> the nuclear industry failed to adequately review, assess, and follow
> up on
> relevant operating experience. Also, the report noted that Davis-Besse
>
> failed to assure that plant safety issues would receive appropriate
> attention, and that the NRC failed to integrate known or available
> information into its assessments of Davis-Besse's safety
> performance.
> * Ten Davis-Besse violations were highlighted in a report issued on
> October
> 2 by the NRC's Augmented Inspection Team (AIT). The team had
> investigated
> the plant's vessel head degradation and FENOC's compliance with
> regulations. The NRC said that the safety significance of the
> violations
> (and any possible enforcement actions) would be determined later. The
> team
> found that FENOC was responsible for:
> 1. Operating the reactor with leakage from the reactor cooling
> system
> through cracks in the control rod drive mechanism (CRDM) nozzles.
> 2. Failing on numerous occasions to thoroughly clean the continuing
>
> buildup of boric acid on the reactor vessel head, which eventually led
> to
> the corrosion of the head.
> 3. Failure to identify the cause of, and take appropriate
> corrective
> actions for, recurrent accumulations of boric acid on the fins of the
> containment air coolers, which resulted in reduced air flow through
> the
> coolers.
> 4. Failure to identify boric acid corrosion as the cause of the
> repeated
> clogging of radiation filters in the containment building and take
> appropriate corrective actions.
> 5. Failure to implement a modification to the service structure
> above
> the reactor vessel head for better access to inspect and clean the
> head and
> the CRDM nozzles.
> 6. Failure to follow the corrective action procedure and complete a
>
> prescribed corrective action for adverse trends in reactor cooling
> system
> leakage, thereby missing an opportunity to identify the nature of the
> leakage and find the growing cavity on the reactor vessel head.
> 7. Failure to establish an adequate boric acid control procedure,
> which
> contributed to the failure, over the years, to properly identify and
> evaluate the leaking CRDM nozzles and the expanding cavity in the
> reactor
> head.
> 8. Recurrent failures to follow the boric acid control procedures
> designed to prevent extensive boric acid corrosion, which resulted in
> the
> failure to remove boric acid deposits and inspect the metal base of
> the
> reactor head as directed by the procedure. 9. Failure to follow the
> plant's corrective action program, designed to
> properly identify the cause of a problem and devise and implement a
> solution, which contributed to FENOC's failure to recognize that a
> through-wall leak had developed in the CRDM nozzles.
> 10. Failure to provide complete and accurate information to the NRC
> and
> maintain internal documents necessary to diagnose and resolve problems
> at
> the plant. Completeness and accuracy of these documents may have
> provided
> an earlier alert to FENOC's staff and to the NRC about the problem
> with the
> CRDM nozzle leakage or may have caused the NRC to establish a
> different
> regulatory position on the urgency for inspecting the vessel head.
> * The NRC on October 16 announced that FENOC was at fault for allowing
> five
> workers to leave the Davis-Besse site in February while wearing
> radiologically contaminated clothing. Microscopic radioactive
> particles
> were later found in hotel rooms and homes in Ohio, Texas, South
> Carolina,
> and Virginia. There was no threat to the public, according to the NRC.
> The
> workers, who had been at Davis-Besse under contractor duties, had been
>
> performing tasks on the plant's steam generator. The steam generator
> work
> was not related to the vessel head degradation discovered at the plant
> in
> early March.
> During a public meeting in Ohio on October 16, the NRC said that
> Davis-Besse did not properly assess how much radiation the workers
> were
> exposed to inside the steam generator. In that regard, the plant had
> failed
> to "conduct timely and suitable measurements of concentrations of
> radioactive material in air in work areas or of concentrations of
> radionuclides excreted from the body," thus compromising the ability
> to
> assess dose, the NRC noted. There also was a failure to adequately
> survey
> the workers prior to their release from the site. NRC officials at the
>
> public meeting said that the agency had not yet determined the
> significance
> of this incident and whether FENOC should be penalized for violating
> NRC
> regulations.
> A report detailing the workers' exposure--along with separate
> reports on
> the Davis-Besse "lessons learned" (see second bulleted item above) and
> the
> AIT investigation (see third bulleted item)--are scheduled to be
> available
> on the NRC's Web site at
>
> www.nrc.gov/reactors/operating/ops-experience/vessel-head-degradation/news.
>
> html>.
>
>
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