ML20055D056
| ML20055D056 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 06/21/1990 |
| From: | Carr K NRC COMMISSION (OCM) |
| To: | Damato A SENATE |
| References | |
| CCS, NUDOCS 9007030155 | |
| Download: ML20055D056 (6) | |
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s June 21, 1990 CHAIRMAN i
The Honorable Alfonse M. D'Amato United States Senate Washington, D.C.
20510-3202
Dear Senator D'Amato:
I I am responding to your letter of May 3, 1990, regarding concerns expressed by Mr. Robert Pollard of the Union of Concerned Scientists with respect to cracks in the steam generators at Indian Point Nuclear Generating Unit No. 2.
In his letters to you of April 18 and 19, 1990, Mr. Pollard concludes that the Nuclear Regulatory Commission (NRC) has placed a higher priority on allowing the plant to resume operation than on protecting the public-safety.
I disagree with his conclusions.
The NRC staff has monitored this issue since it was first dis-covered during the plant's refueling outage in October 1987.
At t
that time, the Consolidated Edison Company (the licensee) dis-covered cracks in the upper head-to-transition cone girth welds on all four steam generators.
After removing all cracks by grinding, the licensee performed an analysis and concluded that the steam-generators still met the original design requirements of the ASME Boiler and Pressure Vessel Code,Section III, and therefore could continue operating.
This analysis included toughness tests of materici that had been heat treated to a condition equivalent to that in the welds and heat-affected zones of the Indian Point 2 steam generators.
In addition to performing this analysis, the licensee committed to perform augmented inspections of the affected areas during the next two refueling outages.
The mechanism responsible for the initiation and growth of the cracks was not determined.
The NRC staff reviewed the licensee's analysis and commitment to perform augmented inspections and l
concluded that the upper head-to-transition cone welds on all four l
steam generators had adequate toughness to preclude fracture of the steam generators during the next fuel cycle.
Hence, the NRC L
concluded that plant operation could safely resume and continue until the next refueling outage that had been scheduled to begin in April 1989.
The licensee detected additional cracking during the first aug-mented inspection which was performed during the refueling outage of April to May 1989.
The licensee's evaluation concluded that
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- The Honorable Alfonse M. D'Amato o the girth weld cracking was apparently due to corrosion-assisted thermal fatigue.
The cracks were again removed by grinding.
The ground-out areas of the most severely affected steam generator girth weld were also repaired by weld buildup.
To minimize thermal stresses, the licensee removed the flow resistance plates from the steam generators and modified the feedwater controls.
The licensee committed to shut down and perform a mid-cycle inspection because the root cause of the cracking phenomenon had not been definitely established.
The NRC staff reviewed the licensee's evaluation and concluded that as a result of the repairs and modifications, vessel integrity would be ensured until the proposed mid-cycle inspection.
Since vessel integrity was ensured, the steam generators were acceptable for continued use, and plant operation could safely resume.
Power operation resumed on July 2, 1989.
The unit was shut down for the mid-cycle inspections on February 24, 1990.
These inspections disclosed additional cracking in the steam generators' girth welds, base material of the steam generator transition cones, feedwater ring supporting brackets, feedwater inlet nozzles, and connecting feedwater piping.
The NRC staff met with the licensee on March 14, 1990, and again on May 21, 1990, to discuss the results of these inspections and to review the licensee's analysis supporting continued operation.
During the May 21, 1990 meeting, the licensee reported that analyses had determined that the cracking in the girth welds, in the base material of the transition cones, and in the feedwater ring supporting brackets was caused by corrosion fatigue and/or stress corrosion, depending on the loads, environment, and loca-tion.
These analyses also determined that the crack initiation occurred at locations with surface pitting that was caused by the presence of oxygen, copper, and stress (residual or applied).
The cracking in the feedwater piping and nozzles was caused by i
corrosion fatigue.
The licensee has removed and repaired all identified cracks in accordance with ASME Code requirements.
The licensee is also making modifications to the plant to reduce the level of oxygen in the water that contributes to pitting and crack initiation.
In addition, the licensee has a program to replace all copper bearing materials in the condensate and feedwater system during the next two refueling outages.
In response to NRC's concern that pitting i
in other parts of the steam generator shells could lead to cracking, the licensee stated that although it had not performed detailed inspections of the lower internal surfaces of the steam generator shells, it had noted that the surface pitting appeared concentrated in the areas near the girth welds.
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The Honorable Alfonse M. D'Amato.
At the conclusion of these meetings, the NRC staff informed the licensee that the steam generators, including internal brackets and feedwater nozzles, must meet the requirements of the ASME Boiler and Pressure Vessel Code for restart and for the duration of the subsequent operating period.
It should be noted that the 1
analyses conducted by the licensee were performed in accordance with the Commission's regulations that endorse the ASME Boller and Pressure Vessel Code Section XI, and included consideration of the maximum additional cracking considered credible during the next period of operation.
In addition, at the May 21, 1990 meeting, the NRC staff requested that the licensee perform a i
visual inspection of one of its steam generators to confirm that the lower interior surface of the steam generator shell is acceptably free of surface pitting.
This inspection was subse-quently completed by the licensee, and the results were reviewed by the NRC staff.
Based on its review of the licensee's analyses and inspection results, the NRC staff has concluded that Indian Point Unit 2 can be safely returned to operation for the remainder of the current fuel cycle.
I believe this record of NRC activities with respect to the Indian Point 2 facility demonstrates responsible regulatory action directed from the outset of the problem at preserving public safety.
I want to assure you that the NRC will continue to monitor the integrity of the steam generators at Indian Point Unit 2 to ensure that the public health and safety will continue to be adequately protected.
Sincerely, bh.0_
Kenneth M. Carr l
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UNION OF
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CONCERNED SCIENTISTS April 18, 1990 Honorable Alfonse M. D'Amato i
United States Senate Washington, DC 20510-3202
Dear Senator D'Amato:
I am writing about a new and serious safety problem at the Indian Point Unit 2 nuclear power plant.
I am bringing this matter to your attention for two reasons.
First, the Indian Point plant is located in Westchester County, only 25 miles north of New York City.
Second, you are already familiar with the failure of the U.S. Nuclear Regulatory Commission (NRC) to ensure public safety.
In September 1987, you released a General Accounting Office report, GAO/RCED-87-141, " Efforts to Ensure Nuclear Power Plant Safety Can Be Strengthened," which you had requested.
You stated, in part, that "the NRC has allowed nuclear plants to keep operating despite findings of design problems (and] questionable The current safety problem at Indian Point equipment.
Unit 2 stems from the NRC allowing operation with defective equipment.
A copy of your press release, your September 22, 1987 letter to I
the Chairman of the NRC, and UCS's September 22, 1987 press release supporting your statements are enclosed for your convenience.
I am also enclosing excerpts from two recent NRC Weekly Information Reports, dated March 21, 1990 (for the week ending March 16, 1990) and April 4, 199G (for the week ending March 30, 1990).
These briefly describe the widespread cracking of all four steam generators in the Indian Point 2 plant, In addition to the information provided in the NRC reports, there i
are a number of other facts which are important to an understanding of the seriousness of the safety hazard posed by the cracking and the apparent unwillingness of both the Consolidated Edison Company (Coned) and the NRC to place a higher priority on protecting the public than on resuming operation of
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Indian Point 2.
Much of the following information is contained in copyrighted articles published in Nucleonics Week on April 6, 1990 and in The Energy Daily on April 16, 1990.
These articles were based on interviews of personnel from Coned and the NRC, including Peter Kelley, NRC's resident inspector at Indian Point, and Donald Brinkman, NRC's project manager for Indian Point.
1 1616 P Street, NW Suite 310 Washington, DC 20036 202 332 0900 FAX: 202 332 0905 Cambridge Hoadouartef t-26 Church Street Camoridge. f.% 02238 617 547 5552 FAX 617 864-9405
The cracking of the steam generators has been growing worse for years.
Coned discovered some cracks in the steam generators during the refueling outage in 1987.
Those cracks were minor and required no repairs.
More severe cracking was discovered during the 1989 refueling outage; cracks were found which were deep enough to require grinding and some weld repairs.
After what NRC's resident inspector called "a lot of back and forth between
' he NRC and Coned," Coned agreed to shut down the plant *>efore the next scheduled refueling to re-inspect the steam generators.
During this shutdown, which began on February 24, 1990, even more widespread cracking has been discovered.
In addition to the fact that the steam generator cracking has been growing worse, the problem is made even more worrisome because the cause of the cracking is not known.
Westinghouse, which was the vendor for Indian Point Units 2 and 3, Coned, and the NRC have been unable to identify the root cause of the cracking.
In J987, the general hypothesis was that the cracks were due to corrosion fatigue.
After the 1989 inspection, Westinghouse posited that the cause was thermal fatigue.
But the latest discoveries of further cracking indicate that the problem is not thermal fatigue.
The NRC has urged Coned to replace the copper-alloyed tubec in the main condenser and Coned plans to replace some tubes with titanium in early 1991, but Coned has told the agency that there is little, if any, copper transfer to the steam generators.
(Copper can be a contributing cause to steam generator damage.)
Furthermore, the cause is unlikely to be chemical in nature because Coned has been following the latest Westinghouse and Electric Power Research Institute standards for steam generator water chemistry.
Another fact is that, although Coned has had new steam generators in storage at Indian Point for years, the utility does not plan to replace the steam generators before 1992.
At Indian Point Unit 3, which-is run by the New York Power Authority, the four steam generators were replaced last year.
l In view of the situation at Indian Point Unit 2, it appears that there is no justification for resuming operation unless and until the steam generators are replaced or the cause of the steam generator cracking has been identified and corrected and the damage which has already occurred has been satisfactorily l
repaired.
I I hope that you will take action to ensure that public safety is the principal basis for future actions at Indian Point Unit 2.
Sincerely,
^
Robert D.
Pollard Nuclear Safety Engineer Enclosures
ALFON$E M. D'AMATO wwemm Enited States 5tnatt WASHINGTON, DC 20510 May 3, 1990 Honorable Kenneth M. Carr Chairman U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Carr:
Enclosed is a letter I have received from Robert D.
Pollard who is a Nuclear Safety Engineer with the Union of Concerned Scientists.
In the enclosed letter, Mr. Pollard outlines his concerns about recent safety problems at the Indian Point Unit 2 nuclear power plant.
In 1987, in response to my flagging concerns over the NRC's effectiveness in providing the public with asseratices that nuclear power plants are operated in a safe manner, the GAO prepared a report entitled " Nuclear Regulation and Efforts to Ensure Nuclear Power Plant Safety Can Be Strengthened".
As you may recall, the report raised serious questions as to whether the NRC has adequately pursued important safety criteria and enforced existing safety regulations.
It is essential that the public be assured that the NRC is doing everything possible to protect it against potential hazards posed by nuclear power plants.
In this regard, I am concerned about the recent safety problems at the Indian Point Unit 2 power plant and request that you provide me with an account of the actions that the NRC has taken and/or is planning to take with regard to this issue.
I look forward to hearing from you at your sar11est convenience.
Sincerely,
/
nse M.
D Amato ted States Senator AMD/kh
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