ML20040A463
| ML20040A463 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 12/18/1981 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | William Jones OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8201210136 | |
| Download: ML20040A463 (7) | |
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DEC 181981 DISTRIBUTION:
Gray File 1
(ITocket FilD RClark NRC PDR SHanauer accket Ho. 50-285 L PDR t.-
TERA i
flSIC Nr. u. C. Jones, Division t'anager ORB #3 Rdg RECEWED Production Operations DEisenhut f
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Onaba Public Pov er District 0 ELD
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1623 Harney Street AE00 s umm an,,
Onaha, Nebraska 68102 IE-3 y
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ACRS-10
Dear Mr. Jones:
ETourigny 4
PKreutzer-3 su i
Ue have reviewcd your "60 day response dated October 20 and November 13, IM1, to our letter dated August 21, 1981, concerning Pressurized Themal l
Shock (PTS). Enclosure 1 to this letter identifies additional information i
needed as a result of our review of your response.
We request that the addi-I tional infornation identified in Enclosure I he provided with your "lS0-day"
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response to our Auqust El letter.
1 In addition, we have been assessino what infomation will be provided in the "150-day" responses due in January 1992 and t'ie infomation expected I
to be sunnlied from the PWR Owners' Group. Since the staff is comitted i
to provide its reconnendations for further actions recarding PTS to the Coreission in the Sprino of 1982, it is important that your "150-day" rosponse to our August 21 letter provide two significant pieces of informa-tion. First, you must provide your basis for continued operation, pending conoletion of any longer tem studies.
We emphasize that continued opera-tion of your facility, withnut any innediate taodifications to your facility 4
or its operation, will be dependent upon our evaluation of your response.
Secondly, your response should fully address the infomation addressed in.
He have prepuep Enclosure 2 to provide anpli tion to the "150-day" infon ation reaued of the Aucust 21, 1981 letter The adiitional infomation requested by the letter should be provided in m
accordance with 10 CP. 50.54(f) of the Comission's requiations.
1 The reporting and/or recordkeepine requirenents of this letter af uct fewer than ten respondents; therefore, OMB clearance is not required under 9.L.96-511.
Sincerely, Original signed by:
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8201210136 811218 Thomas M. !!ovak, Assistant Director PDR ADOCK 05000285 for Operating Reactors P
PDR Division of Licensing i
Enclosures:
1.
Evalua tion of the "60-day"
- see previous 318 Response to 8/21/81 Ltr.
for concurrence.
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i i (3) Your assessment of the sensitivity of your analyses to uncertainties i
in input values, such as initial crack size, copper content, fluence, and inital reference terperature at welds.
i (4) A list of assunptions relied upon in reaching your conclusions.
i a.
If this list includes " credit" for onorator actions, describe the basic instructions given the operators (for exanple, if a "sub-cooling" band is used, describe it). Submit the procedures the nperator will fellow, and describe the training being given to establish operator readiness to cope with PTS cvents.
b.
If the list includes credit for the effects of warn prestres' sing for sone event sequences, include your justification and analyses 1
showing that such events will folleu a pressure-tmperature pat'1-way for which warm pre-stress is effective.
1 The reporting and/or recordkeeping requirenents of this letter affect j
fewer than ten respondents; therefore, OMB clearance is not required under P.L.96-511.
i Sincerely, i
l-Thonas M. !!ovak, Assistant Director i
for Operating Reactors i
Division of Licensing
Enclosure:
Evaluation of 60 Day l
Response to 8/21/81 NP.C ltr. on PTS &
j Request for Additional i
Infomation l
l cc w/ enclosure:
See next page l
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OFFICIAL RECORD COPY usceo; iesi-225-ee.
psc ronu ais 00-80, NRCM Ono
Onaba Public Power District cc:
Marilyn T. Shaw, Esq.
LeBoeuf, Lanb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
Washington, D. C.
20036 Mr. Emmett Rogert Chairman, Washington County Board of Supervisors Blair, Nebraska 68023
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U.S. Environmental Protection Agency i
i Recion VII ATTN:
Regional Radiation Representative 324 East lith Street K a n s a s C i ty, r.'. s sou ri 64106 Mr. Frank Gibscn W. Dale Clark Library 215 South 15th Street Omaha, Nebraska 68102 Alan H. Kirshen, Esq.
el l-:., n.t c ey ! '.i rsht-r lif6 JoOd en Io..;r
- s na, !.'ebraska 65102
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P.r. Charles E. Erir.i5an "anager
'.lashir.gton Nuclear 0;eretiens C-E Power Systems Combustion Engineering, Inc.
4853 Cordell Avenue, Suite A-1 Eethesda, Ucryland 20014 l
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ENCLOSURE (1)
EVALUATION OF THE OMAHA PUBLIC POWER DISTRICT 60 DAY RESPONSE TO THE NRC LETTER DATED AUGUST 21, 1981, CONCERNING PRESSURIZED THERMAL SH0CK (PTS)
AND REQUEST FOR ADDITIONAL INFORMATION FORT CALHOUN STATION i
DOCKET NO. 50-285 1.
RTNDT Values Initial RTNDT for the welds was the subject of a letter dated November 13, 1981, which supplemented your "60 day" response of October 20, 1981. We still have some questions that lead us to not accept your new value of -500F for the initial RTNDT of the longitudinal beltline welds. The archival material that was tested recently was the surveillance weldment. According to your letter of September 8, 1977, the weld wire and weld flux for the surveillance weld were not the same as for the longitudinal welds, as shown in Table I.
Also from that letter, the drop weight RT NDT was also 00F. NDT of the surveillan welds was reported to be OoF, and RT It is not c, lear why the recent test of the archival material should give a value 50 degrees lower.
We are inclined to use the generic upper 2rvalue of -200F described in your October 20 and November 13 letters.
This is partly because of the discrepancies described above and partly because -200F is approximately the Charpy 30 ft. lb.
level shown for the surveillance weld.
If the peak ID fluences as provided in your letter dated October 20,1981 are 2
not the fluence values for the critical longitudinal welds, provide the peak'
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fluence values at the critical longitudinal welds. When the above is provided we will then be able to determine current RTNDT values which we will use in our independent assessments.
2.
The Rate of Increase of RTNDT We accept your value for increase in RTNDT from 5.36 EFPY (December 31, 1981) to 8.56 EFPY (December 31,1985) it it represents the value at the critical longitudinal weld.
From this can be obtained the rate of int. 'ase of RTNDT per EFPY.
In addition,as a check on our calculation, please provide the expected rate of fluence increase per EFPY taking into consideration any contemplated changes in core configuration.
- 3. & 4.
RTNDT Limit and Basis for the Limit Since the "60 day" response stated that you do not consider a limit on RTNDT to be an appropriate basis for continued operation, the staff needs to develop a quantitative criterion for continued operation that, if implemented, would 1
assure maintenance of an acceptable low risk of vessel failure from PTS event for the near-term, pending longer term results of more detailed analysis or research. We will be developing this criterion considering recommendations that you may provide in your "150 day" response.
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2-5.
Operator Actions The extent to which the overall concern of thermal shock is being emphasized at Fort Calhoun has been the subject of discussions between staff personnel (Project Manager and Resident Inspector). From these discussions we recognize that PTS has received some emphasis in training and procedures and the operators 1
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are sensitive to thermal shock consideration. However, we cannot determine from your "60 day" response to our letter of August 21, 1981, the degree of emphasis which is currently placed on the need for changes in procedures, training and management involvement.
We request that you expand your response to provide us a more detailed discus-sion of what steps have been taken to ensure that your operators have a firm grasp of this issue and can be expected to cope with the events which serve to initiate PTS.
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TABLE I I
Filler Metal Flux a
j Type Heat flo.
Tyae Heat No.
I Surveillance Weld B-4, 305414 Linde 1092 3951 3/16" i
I Intermediate Shell f
Long, Seams 2-410 3-4 51989 Linde 124 36G7 3/16" I
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ENCLOSURE (2)
AMPLIFICATION OF THE "150-DAY" REQUEST TO THE AUGUST 21, 1981 LETTER (1)
Identification of the PTS events that were considered in reaching your conclusions, and a justification for PTS events that you did not consider. You should include a quantitative assessment of the probability of occurrence of the various PTS events considered and not considered and an accompanying assessment of the likelihood of vessel failure vs. EFPY for the events. The manner in which you considered multiple failures of systems, components, and those resulting from operator actions should be described in detail.
(2)
A description of the steps, if any, you are taking now or plan to take in the near future to delay the rate of further embrittlement of your vessel, and your assessment of the effectiveness of those steps.
(3)
Your assessment of the sensitivity of your analyses to uncertainties in input values, such as initial crack size, copper content, fluence, and initial reference temperature at welds.
(4)
A list of assumptions relied upon in reaching your conclusions, a.
If this list includes " credit" for operator actions, describe the basic instructions given the operators (for example, if a "sub-cooling" band is used, describe it). Submit the procedures the operator will follow, and describe the training being given to establish operator readiness to cope with PTS events.
b.
If the list includes credit for the effects of warm prestressing for some event sequences, include your justification and analyses showing that such events will follow a pressure-temperature pathway for which warm pre-stress is effective.