ML20215B592
| ML20215B592 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/08/1987 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Rosenthal J NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML20215B065 | List: |
| References | |
| FOIA-87-20 NUDOCS 8706170377 | |
| Download: ML20215B592 (10) | |
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7p VIROINIA Ex.ecTarc ann Powen COMPANY g
RIcnwoNn,VIROINIA 20261 April 8, 1987
- w. L. srswar v8CE PRESIDENT Nt:ct. sam orsaAvious Mr. Jack E. Rosenthal, Chief Serial No.87-185.
Events Analysis Branch N0/NEC:jmj U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Rosenthal:
- We appreciate the opportunity to comment on IE Draft Bulletin: " Thinning'of Pipe Walls in Nuclear Power' Plants."
Virginia Electric y and Power Company believes utility industry initiatives have been timely and will be effective in addressing the issues raised as a result of the. December 9, 1986, Surry Pipe Rupture Event.
These initiatives include:
seminars held at six locations around tha country on February.10, 1987 to disseminate information on the event and the erosion / corrosion phenomena; issuance of a Significant Event Report (SER) and a Significant Operating Event Report (SOER).by the Institute ~ of Nuclear Power Operations (INPO); coordination with the Electric Power Research Institute (EPRI) to collect technical information and sponsor a workshop on erosion / corrosion on April 14-15, 1987; and the formation of an wrosion/ corrosion working group under the Nuclear Utility Management and Resource Council (NUMARC) to develop industry guidelines and provide a consistent industry respons6. Through these efforts the industry has shown an aggressive response -to the Surry event and has made substantial progress in exchanging information and planning appropriate actions.
Therefore, it is Virginia Electric and Power Company's positfon that it_is not necessar.y for the*
NRC to mandate industry attention and response by issuance of an IE Bulletin.
However, in the event that NRC Staff is compelled to issue a Bulletin, the, following comments are offered:
Based on a review of the scope of the questions, it is our opinion that a 45 day response period would be insufficient to allow for a thorough response.
In as much as the term "important-to-safety" is not uniformly defined or understood throughout the industry, we believe it is too ambiguous a term to be used in this bulletin. It is recommended that the NRC specifically define systems (by function) or list specific technica3 criteria such as those in our report of January 14, 1987 for selectiori of systems to be investigated.
It is our opinion that the phenomena of erosion /norrosion in two phase flow systems has already been documented by the NRC and addressed by the industry.
On July 9, 1982 the NRC issued an IE Information Notice and on November
'17, 1982 INPO issued SOER 82cl1 after the Oconee event. ~ 'recent telephone sitrvey A
conducted by INPO combined with the results of INP0's evaluation process in reviewing satisfactory completion of SOER recommendations indicates that greater than 85% of plants surveyed (67 sites) have programe ~ r inspection of two-phase flow systems.
Requesting information on these programs dilutes resoarces to quickly respond to the current single-phase issue. Information on fez ~A f7'DO B706170377 870611 gy FOIA PDR PDR IWELLING67-tq
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two-phase flow inspection programs could therefere be reviewed and/or gathered by the Resident Inspector.
In general, we believe that questions 1-5 could be abandoned in favor of two simpli' focused areas to be addressed by licensees. First, the 1icensee'should provide the scope, results and subsequent actions of any inspections conducted as' a result of the Surry event. Finally, the licens~ee should provide the selection and acceptance criteria, scope, and schedule for any.
future inspections planned.
If none are planned for the next major outage, a justification should be required.
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In summary, we believe that the actions as'a whole by the industry have been timely and that future activities as committed by NUMARC will be sufficient.
Again we appreciate this opportunity to comment.
Please centset us if you desire'a'dditional information'.
' Very truly,yours, W
A W. L. Stewart e
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Suite 2900:
Atlanta, GA '30323 U. S. Nuclear Regulatory Commission Attention Document Control Desk' Washington, D.C.
20555 Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station
.Mr. J. L. Caldwell NRC Senior ~ Resident Inspector North Anna Power Station e
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William N. Curry k804)771-3620 February 11, 1987 VIRGIN!A POWER ESPON05 70 NRC REPORT ON $URRY ACCI_ DENT l
Virginia Power on Wedneiday began the initial steps leading to a resumption of full operation of Unit l'at the Surry Power Station. The company's action came after it received authorization from the U.
S.
Nuclear Regulatory Comission to restart both Surry units in accordance with the company's inspection, repair and nEw maintenance program developed as a result of the Dec. 9 feedwater pipe rupture at Unit 2.
.The company expects Unit 1 to return to service next week and Unit 2 in late Febru'a'ry.
1 The NRC's authorization to restart Surry units 1 and 2 was part of a 54-page NitC inspection report on the pipe rupture, which fatally injured four contract verkers in the non-nuclear turbine building of Unit 2.
The report re asserts that there was no radiation release or exposure as a result of the accident.
The report also confirms Virginia, Power'sfindingthatthepipefailed because of erosion and co'rrosion of the pipe walls associated with the design-induced turbulence in the 380-degree Fahrenheit feedwater system. "We are pleased with the report and agree with the findings," William L.
Stewart.
J Virginia Power vice president-nuclear operations, said.
"It confirms our j
findings and gives Virginia Power and its employees due credit in our response to this unforeseeable and fagic accident."
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The NRC report concludes that, overall, Virginia Power responded properly to the event - specifically highlighting the response by control room operators, the emergency response orgahization and plant security forces. The report also points out that Virginia Power inoved quickly to inform the public and news organizations, beginning shortly after the accident and continuing for several I
weeks thereafter.
Stewart said the contany will " aggressively review and pursue" all i
recommendations in the report, although, he noted, the company already has implemented a number of the procedures. Specifically, Stewart said Virginia i
Power has begun a valve operability program to follow maintenance work.
The NRC included with its report a " notice of violation" citing the company i
for failure to provide an abequate procedure for reassembly of the main steam trip valve.
Such a valve slammed shut Dec. 9 because of an improperly installed valve cover. Virginia Power has said, and the NRC report concurs, q
however, that the feedwater pipe wall on Unit 2 had worn so thin that a rupture was inevinble, regardless of the valve closure.
Whilelfrginia Power had a maintenance procedure for the main steam trip
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valve prior to Dec. 9, it did not properly address reinstallation of the valve cover.
Virginia Power will not contest the notice.
On other issues raised by the NRC report, Stewart said the company:
Is pursuing measures to improve the safety of control room operators, such as providing oxygen-lekel monitors..
Will review the report's discussion of water chemistry to see what measures may be warranted.
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f"ag UNITED STATES f
n NUCLEAR REGULATORY COMMISSION e
OFFICE OF PUSLIC AFFAIRS, REOlON 11 101 Marietta Street, N.W., AM.UfTA.GEORGaA 303o3 E
II-76-12 FOR DNEDIATE RELEASE I
Contact:
Fan Clark or Joe Gilliland (Wednesday, February 11, 1987)
Telephone: 404/331-4503 5
INSPECTION REPORT ISSUED ON FEEDWATER LINE BREAK ACCIDENT AT SURRY PLANT The Nuclear Regulatory Commission has issued its Augmented Inspection Team report on the break of an 18-inch feedwater suction line December 9,1986, at Unit 2 of the Surry nuclear plant, near Surry, Virginia. The accident injured eight persons, four of them fatally, and damaged some non-nuclear plant components.
No one was radioactively contaminated, and there was no radiation release to the environment.
Included with the inspection report, issued February 9, is a formal Notice i
of Violation citing Virginia Power for failure to provide an adequate procedure for reassembly of a main steam line isolation valve after maintenance had been performed. The inadvertent closing of this valve caused the Surry Unit 2 reactor to shut itself down, initiating t.he accident (although examination of the broken pipe showed that its wall had been wsrn so thin tSt any normal pressure surge would have caused the break). In its post-accider.; investigation, Virginia Power found, and reported to the NRC, that the steam line valve was improperly reassem-bled after.being overhauled last October. NRC inspectors confinned the finding.
The Notice of Violation--which does not involve a monetary fine--requires Virginia Pow *ee to inform the NRC within 30 days of measures it is taking to correct appropriate maintenance procedures. The inspection report notes that the improper reassembly did not prevent the valve from perfonning its safety function.
The 54-page report also:
- Authorizes Virginia Power to restart both Surry units in accordance with the company's inspection, repair and preventive maintenance program.
This authorization is based both on the Augmented Inspection Team's independent evaluation and on NRC's assessment of the Surry restart plan. The report notes that the water erosion and corrosion which caused the line break was found to be
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limited to the plant feedwater and condensate system, and points out that inspec-tions of other systems will continue.
The. day after the accident occurred in J
Unit 2, Virginia Power shut down Surry Unit 1 for inspection, and sgreed not to restart either unit without NRC concurrence.
Since the shutdown Virginia Power has checked feedwater and condensate piping in both units and is replacing some components.
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- Generally concurs with Virginia Power's finding that the 18-inch pipe broke because of extensive wall thinning, caused by erosion and corrosion.
In some places, the pipe wall was worn from a nominal thickness of half an inch to as little as one-sixteenth of an inch, and in at least one instance to i
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48-thousandths of an inch.
The. major contributor. to this wall thinning is believed to be the corrosion caused by the turbulence of water flowing at high i
speed from a 24-inch header pipe through a T-shaped connection in the 18-inch line and then imediately through a' pipe elbow. The. report agrees, however, that water chemistry was also a contributing-factor.
The' report cover letter says Virginia Power should " expeditiously" complete a review of water chemistry i
control procedures. NRC did not substantiate a concern raised by a former Surry j
employee that pipe grinding by carpenters may have contributed to the break. It 1
was found that such workers were used only for cleaning or buffing pipe welds in preparation for nondestructive examination.
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- Recomends that Virginia Power consider some additional means, in addition to those it has already instituted, to assure safety of control room workers.
This recommendation is made because water and steam blown out of the broken feedwater line flowed into soce control panels and switches, causing fire-protection systems to discharge carbon dioxide and Halon in some plant areas and to be vented into the control room.-
Some control room personnel briefly I
experienced dizziness-and shortness of breath before emergency air supply fans.
were turned on to clear the room. NRC recommends procedures and warning devices that would alert operators quicker of future such occurrences and improve their j
ability to deal with them.
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- Agrees with Virginia power that, while one feedwater pump discharge valve wcs not fully seated and-similar valves on other ieedwater pumps showed wear and tear, these conditions did not contribute to the pipe break..
- C6nclides that,'overall, Virginia Power responded properly to the event.
The report specifically highlights the response by control room operators, the emergency response organization and the plant security forces. ~ It also points
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out that Virginia Power moved quickly to inform the public and news organiza-tions, beginning shortly after the accident and continuing for several weeks thereafter.,
The Augmented Inspection Team first went to the Surry plant within hours of the accident on December 9.
It remained on site for several days, returning at various times before concluding its on-site activities on January 14. Eventually j
12 NRC staff members participated in the inspection.
Because of the accident, q
NRC issued an Information Notice on Gecethber 16 to all nuclear plants in opera-tion and under construction, telling of a. potentially generic problem with feedwater pipe thinning and other matters.
NRC also convened a meeting on January 12 in Washington to discuss the incident's generic aspects with specialists from throughout the nation.
The NRC staff also has briefed the Advisory Committee on Reactor Safeguarc's and will brief members of the Commission later this month in Washington.
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(EDMORS: 'Ihis information has also been released by the NT in Washington, D. C.)
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