ML20040B084
| ML20040B084 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 12/30/1981 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Burstein S WISCONSIN ELECTRIC POWER CO. |
| References | |
| TAC-48122, NUDOCS 8201250121 | |
| Download: ML20040B084 (7) | |
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Docket No. 50-266 TERA
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Pr. Sol Burstein
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Executive Vice President ID'
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Milwaukee, Wisconsin 53201
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Dear Pr. Gurstein:
x PM-TColburn We have reviewed your Hovember 19, 1981 Ketter' outlining your planned steam
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generator inspection and operating interval for Point Beach Nuclear Plant Unit 1.
In that letter you state your intent to return Unit I to power operatfor i
on or about December 6, 1981 at a maximun hot leg temperature of 5750F except
-l for relatively brief testing intervals of up to several days in length. You also dtate that bLsed on the " apparent marked reduction in steam generator tube corrosion rate" interpreted from the Unit I steam generator tube inspec-tion results (licensee event report' No. 81-017/01T dated November 13,1981),
you believe it is appropr. ate to operate Unit I until the normal fall 1982 j
refueling outage before conducting the next steam generator tube inspection.
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Previous to your evaluation of these latest inspection results, Mr. Porter j
of your staff testified under oath of your intent to conduct a mid-cycle steam i
generator tube inspection, s6metime in 1982. Further.Mr. Porter testified
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that "if the Unit I steam generator tubes are not sleeved in the fall of 1982 j
then it's likely that the steam generators would be replaced in 1983 rather l
than sleeved at that time"(see transcript pages 288-289 in the matter of Wisconsin Electric Power Company Point Beach Nuclear Plant Units 1 and ? dated October 29, 1981) indicating that the d4qradation and rate of corrosion in the Unit 1 steam generators is at a very advanced level.
It is the staff's strongest recommendation that you conduct a mid-cycle steam generator eddy current inspection and the associated hydrostatic tbsts on Unit-I for the following reasons: (1) Fr. Porter testified during the October 29-30 1
hearing that the information gained from the inspection of sleeved tubes that i
have been operating is useful but not essential to the decision making process j
of a full scale sleeving operation, llowever, the staff feels that.this informa-l tion is very useful and should be obtained during mid-cycle to provide an additional data point which, besides allowing greater time for more careful evaluation i
of the data would provide a gycater data base for. trend analysis. (2) The staff i
does not agree with your in h eence in the narrative of LER 81-017/01T 0 dated 11/13/81 that the corrosion rate in Unit 1 stean generators is continu1ng to decrease because only seven new indications were found, i
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- Bearing in mind that this inspecticn interval was much shorter than the previous interval of 150 EFPD, seventeen tubes were found to have pluggable indications (>40%) during this inspection as opposed to only four tubes during the July 1981 inspection. Also, the number of tubes exhibiting signal change when comparing the October 1981 inspection results to the July 1981 inspection results is greater than the number observed when comparing the July 1981 inspection results to the December 1980 inspection resul ts. This suggests to the staff that the corrosion rate for a given period of time has increased as a result of operating with the hot leg temperature at its present value as opposed to the lower value you voluntarily imposed during the period of November 1979 to July 1981.
Although the staff concedes that the corrosion rate experienced by the Point Beach Unit 1 steam generators is presently less than that experienced just prior to issuance of the November 1979 Confirmatory Order for Modification of License DPR-24, it has been the staff's intention, historically, to relax the steam generator eddy current inspection frequency requirements of that Order and subsequent modifying Orders
' based upon a continually decreasing corrosion rate as evidenced by the results of each of the preceding steam generator eddy current inspections.
This is so as to closely monitor the corrosion rate that exists within the generators and thereby prevent that rate from accelerating beyond our control.
It is our intention to continue to closely monitor the corrosion rates on the Point Beach Unit 1 steam generators and it is in this regard that we strongly urge you to conduct a mid-cycle steam generator tube eddy current inspection.
Confirmatory Orders for Modification of License DPR-24 dated November 30, 1979 as modified by orders dated January 3,1980 and April 4,1980, which li.: posed more strict leakage requirements, lower reactor coolant radio-activity levels and reduced reactor coolant system pressure linits are still in effect on Point Beach Unit 1.
However, the staff feels that the interval between inspections should be defined consistant with the goal of achieving as low a primary coolant leakage rate as is reasonably attainable. The frequency of inspections should be such that non-pluggable indications have a very high probability of not leaking prior to the next scheduled steam generator inspection. The occurence of small leaks during nomal service may indicate a situation where additional tubes are in a condition of incipient leakage. Steps taken to promote continued minimum leakage operation (e.g. frequent tube inspections) provide added assurance against excessive leakage during postulated accident conditions.
The staff feels that your proposed operating interval will significantly increase the likelihood that a leak will occur prior to the next scheduled inspection outage and therefore considers your proposal to be imprudent.
The latest inspection outage (October 1981) suggest an increase in the rate of corrosion, although we believe that this rate is still significantly less than what was observed prior to November 1979 when the unit was operated at 100% power with a 600 F hot leg temperature.
Considering your proposal to operate Unit 1 at 575 F hot leg temperature including some periods in January 1982 at 100% power, when hot leg tecperature l
will be higher, we believe it is inappropriate to operate beyond mid-cycle l
without perflorming7ncth r steam generator inspecti on.
You'are requested l
l omcr y.to. respond..to...this...l atter.within 30.. days.cf..thi s..de te.........
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The reporting requirements of this letter affect fewer than 10 respondents; therefore OMB clearance is not required under P.L.96-511.
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Sincerely, D4ntie'gwi by:
l Thomas ti. Novak. Assistant Director for Operating Reactors Division of Licensing cc: See next page
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Mr. Sol.Burstein Executive Vice President Wisconsin Electric Power Company 231 West. Michigan Street Milwaukee, Wisconsin 53201
Dear Mr. Burstein:
WehaYerehiewedyourNohember 19, 1981 letter outlining your. planned stmm generator inspection and operating interval for. Point Beach Nuclear Plant Unit 1.
In that letter you state your intent to return Unit 1 to power operation on or about December 6, 1981 at a maximun hot leg temperature of 5750F.except for relatively brief testing intervals of up to several days in length. You also state'that based on the "appare6t marked reduction in steam generator tube corrosion rate" interpreted from the Unit 1 steam generator tube inspec-tion results (licensee event report No. 81-017/0lT dated November 13,1981),
you believe it is appropriate to operate Unit 1 until the normal fall 1982 refueling outage before conducting the next steam generator tube inspection.
Previoustoyourehaluationoftheselatestinspectionresults,Mr. Porter of your staff testified under oath of your intent to conduct a mid-cycle steam generator tube inspection, sometime in 1982. Further.Mr. Porter tes+.ified
~
that "if the Unit 1 steam generator tubes are not sleeved in the fall of 1982 then it's.likely that the steam generators would be replaceo in 1983 rather than sleeved at that time"(see transcript pages 288-289 in the matter of Wisconsin Electric Power Company Point Beach Nuclear Plant Units leand 2 dated October 29, 1981) indicating that the degradation and rate of corrosion in the Unit 1 steam generators is at a very advanced level.
It is the staff's strongest recommendation that you conduct a mid-cycle steam generator eddy current inspection and the associated hydrostatic tests on Unit 1 for the following reasons: (1) Mr. Porter testified during the October 29-30 hearing that the information gained from the inspection of sleeved tubes that have been operating is useful but not essential to the decision making process.
of a full. scale sleeving operation. However, the staff feels that.this informa-tion is very useful and should be obtained during mid-cycle to provide an additional data point which, besides allowing greater time for more careful evaluation of the data would provide a greater data base for. trend analysis. (2) The staff does not agree with your inference in the narrative of LER 81-017/01T-o dated 11/13/81 that the corrosion rate in Ur.it 1 steam generators is continuing to decrease because only seven r w indications were found.
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Bearing in mind that this inspection interval was much shorter than the previous interval of 150 EFPD, seventeen tubes were found to have pluggable indications (>40%) during this inspection as opposed to only four tubes during the July 1981 inspection.
Also, the number of tubes exhib1 ting signal change when comparing the October 1981 inspection results to the July 1981 inspection results is greater than the number observed when comparing the July 1981 inspection results to the December 1980 inspection resul ts. This suggests to the staff that the corrosion rate for a given period of time has increased as a result of operating with the hot leg temperature at its present value as opposed to the lower value you voluntarily imposed during the period of November 1979 to July 1981.
Although.the staff concedes that the corrosion rate experienced by the l
Point Beach Unit 1 steam generators is presently less than that experienced just prior to issuance of the November 1979 Confirmatory Order for Modification of License DPR-24, it has been the staff's intention, historically, to relax the steam generator eddy current inspection frequency requirements of that Order and subsequent modifying Orders based upon a continually decreasing corrosion rate as evidenced by the results of each of the preceding steam generator eddy current inspections.
This is so as to closely monitor the corrosion rate that exists within the generators and thereby prevent that rate from accelerating beyond-our control.
It is our intention to continue to closely monitor the corrosion rates on the Point Beach Unit 1 steam generators and it is in this regard that we strongly urge you to conduct a mid-cycle steam generator tube eddy current inspection.
. Confirmatory Orders for Modification of License DPR-24 dated November 30, 1979 as moaified by orders dated January 3,1980 and April 4,1980, whicn imposed more strict leakage requirements, lower reactor coolant radio-activity levels ar.d reduced reactor coolant system pressure limits are still in effect on Point Beach Unit 1.
However, the staff feels that the interval between inspections should be defined consistant with the goal of achieving as low a primary coolant leakage rate as is reasonably attainable. The frequency of inspections should be such that non-pluggable indications have a,very high probability of not leaking prior to the next scheduled steam generator inspection. The occurence of small leaks during normal service may indicate a situation where additional tubes are in a condition of incipient leakage. Steps taken to promote continued minimum leakage operation (e.g. frequent tube inspections) provide added assurance against excessive leakage during postulated accident conditions.
The staff feels that your proposed operating interval will significantly 1
increase the likelihood that a l'eak will occur prior to the next scheduled inspection outage and therefore considers your proposal to be imprudent.
The latest inspection outage (October 1981) seggest an increase in the rate of corrosion, although we believe that this rate is still significantly less than what was observed prior to November 1979 when the unit was operated at 100% power with a 600 F hot leg temperature.
Considering your proposal to operate Unit 1 at 575 F hot leg temperature including some periods in January 1982 at 100% power, when hot leg temperature will be higher, we believe it is inappropriate to operate beyond mid-cycle without performing another steam generator inspection.
Yourare requested to respond to this letter within 30 d'ays of this date.
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3-i The reporting requirements of this letter effect fewer than 10 respondents; therefore, OMB clearance is not required under P.L.96-511.
i Sincerely, 17 Thomas M. Novak, Assistant Director 3
for Operating Reactors Division of Licensing i
cc: See next page 4
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Wisconsin Electric Power Company
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cc:
Mr. Bruce Churchill, Esquire Mr. William Guldemand Shaw, Pittman, Potts and Trowbridge USNRC Resident Inspectors Office 1800 M Street, N. W.
6612 Nuclear Road Washington, D. C.
20036 Two Rivers, Wisconsin 54241 Joseph Mann Library Peter B. Bloch, Chairman 1516 Sixteenth Street Administrative. Judge Two Rivers, Wisconsin 54241 Atomic Safety and Licensing Board U.S. Nuclear Regulatory Cannission
.Mr. Glenn A. Reed, Manager Washington, DC 20555 Nuclear Operations Wisconsin Electric Power Company Dr. Hugh C. Paxton Point Beach Nuclear Plarr Administrative Judge 6610 Nuclear Road 1229-41st Street Two Rivers, Wisconsin 54241 Los Alamos, New Mexico 87544 Mr. Gordon Blaha Dr. Jerry R._Kline Town Chairman Administrative Jadge Town of Two Creeks Atomic. Safety and Licensing Board Route 3 W.S. Nuclear Regulatory Cammission Two Rivers, Wisconsin 54241 Washington, DC 20555 Ms. v.athleen M. Falk Francis X. Davis General Counsel P. O. Box 355 Wisconsin's Environmental Decade Pittsburgh, PA 15230 114 N. Carroll Street
_a
'iadi st, Wisconsin 53703 J. S. Environmental Protecticn
- gen:y Federal Activities Branch Region Y Office ATTN:
Regional Radiation eoresentative 230 S. Dearborn Street Chicago, Illinois 60604 i
Chai rman Public Service Commission of Wisconsih Hills Farms State Office Building Madison, Wisconsin 53702 M
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