ML18139A081
| ML18139A081 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 01/21/1980 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Proffitt W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| Shared Package | |
| ML18139A079 | List: |
| References | |
| NUDOCS 8003280169 | |
| Download: ML18139A081 (3) | |
Text
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JnN 2 1 1980 Docket Nos. 50-388 and 50-339 Mr. W. L. Proffitt Senio*r Vice President - Power Virginia Electric and Power Company Post Office Box 26666 Richmond, Virginia 23261
Dear Mr. Proffitt:
SUBJECT:
INSTALLATION OF INSPECTION PORT ON STEA.f-1 GENERATORS AT NORTH ANNA POWER STATION, UNITS 1 AND 2 Accumulating information indicates that the steam generators in comnercial pressurized water reactors are showing problems including tube cracking 9 support plate corrosion and increased denting of steam generator tubes.
I am concerned that.the progression of tube denting now occurring is not being adequately addressed with respect to ongoing investigations and to the development of preventative measures to eliminate this problem.
As you know, recent steam generator problems, such as occurred at your Surry Power Station, have led to extensive shutdown periods. The NRC staff strongly believes increased surveillance measures are necessary to monitor the progression of tube denting in steam generators and to be able to remove tube section$ for laboratory examination.
Therefore, to facilitate monitoring the progression of denting, access ports, similar to those at Surry and other plants, should be installed just above the upper support plate in each steam generator. These ports should be of adequate size and location to allow inspection of the upper sup~ort plate and upper support plate flow slots and to permit the removal of selected tubes.
Therefore, in addition to-your December 10, 1979 cormiitment to install these t..,.o
.A, inspection ports ~t North Ann~ Power Station Unit ~ ~rior to i:-estart after~.,.~ l\\e.{':*1 1
- the second refueling, we require that you make a s1m11ar commitment _for t"'
Lt"~ i\\
North Arina Power Station Unit 2 prior to start of commercial operation.
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cc: See next page
~ :\\1, Sincerely; Vi>-v.\\
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D. F".
oss, Jr., Acting Director Division of Project Management Office of Nuclear Reactor Regulation 8 0 03 2 80( ~ 4
NO.Rn~ ANNA J1;NVIRONIVlENJ iL COAUTION Charlottesville, Virginia 9"..
l!ailing.D..ddrees:
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DEFECTIVE STEAM GE?iERATORS* ~~Op~_~_W;D_~f~.9-~;.f.fe~~ (ZOS) 636-0G?S.
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FOUND AT NORTH ANNA REACTOR 1/1 Di.:*~~i:.::~~ :\\~:".~22ii If Westinghouse steam generators deYelop defec_ts !r~~if;I~;~~voi~:JJs.l1~=L.
Westinghouse steam generators develop defects at North Anna? asked NAEC in 1976 and 1977 0£ NRC's Advisory Committee on Reactor Safeguards (ACRS) and Atomic Safety and Licensing Board (ASLB).
VEPCO reassured the ACRS and ASLB that such would not happen at North Anna.
Then ca.me the accident of September 25, 1979 which allowed radioactive gas to escape from the North Anna reactor for three hours.
The plant shut do\\:ill, and VEPCO and Westinghouse be~an to inspect North Ann's steam generators.
is what they found:
" *** for 888 tubes inspected, 35% showed indications of support plate corrosion or crac;;kin, at the intersections **
" *** testing indicated the presence of support plate corrosion (or crackin~) at support plate/tube intersection for 306 tub~~
- Westinghouse stated that this plate corrosion at the inter-sections is full blown.
,!i also stated that support plate cor-rosion occurs before cracking *** "
DOC!<>:TED How could this happen? When NAEC raised the steam generator tube problem before the ACRS in 1977, VEPCO stated that demineralizers mitigate the corrosive quality of the water.
Here, again, is NRC's report of December 19, 1979:
"Westinghouse stated that the support plate damage observed was caused by the inadvertent dumoing of 200-300 pounds of resins from the polishers of the full flow demineralizers into the SG 1s. Sulphonic acid at high temperature produced sulfuric acid which attacked the carbon steel. ** 11 How dangerous are defective steam generators? The LEWIS RISK ASSl.sS~T REVIEW cites tube failures "like those at Surry 2" as possible contributors to the probability of a.core melt.* ( The first steam generator replacement in the
- the "China syndrome" history of the commercial nuclear industry begari at Surry #2 in :February of 1979.) Surry 1s years of defective operation increased radioactive releases, both liquid and gaseous~ and caused high exposure of repair personnel.
The NRC has asked VEPCO "to provide information for the occupational exposures which have been incurred during the inservice inspection or are expected to result from corrective actions on the SG's" at North Anna #1.
NRC also asked VEPCO "to provide data on any observed iodine spiking which may have_ occurred during the first cycle of operation." An increase in Iodine-131 signals steam generator leakage. When a steam generator tube ruptures, noble gases are released such as xenon.
Clean-up at North Anna #1:
According to the 12-19-79 NRC report, VEPCO and Westinghouse are working on a "clean-up procedure for the SG's" at North Anna 1/1 which includes "soaking in hot water for a period of four to five days."
Comparable problems abroad: According to the MANCHESTER GUARDIAN of 10-25-79, 11 *** 25 of 26 French-built systems recently found cracking in. their steam generator pressure plates *** A crackdown on nuclear information reaching the public has been ordered by the French Government after the discovery that radioactive primary coolant is leaking into the secondary steam circuits at the Bugey-2 reactor near Lyons."
Framatome in France, a giant nuclear consortium, has worked with Westinghouse designs.
NAEC believes that this kind of information about serious reactor defects should be carefully studied by those Virginia government officials who have been urring the rapid licensing of North Anna #2 and making statements about its safety *
. ~.*