ML20040F654
| ML20040F654 | |
| Person / Time | |
|---|---|
| Issue date: | 01/27/1982 |
| From: | Faulkner H Office of Nuclear Reactor Regulation |
| To: | John Miller Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20040F655 | List: |
| References | |
| NUDOCS 8202100034 | |
| Download: ML20040F654 (6) | |
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4 RECEIVED f f pE88 1982> k2' MEMORANDUM FOR:
James R. Miller, Chief Standardization & Special Projects Branch, u mu narm mnra.
Division of Licensing ra uua n 4
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FROM:
H. J. Faulkner, Project Manager Standardization & Special Projects Branch 4
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SUBJECT:
SUMMARY
OF MEETING WITH BWR OWNERS' GROUP ON DECEMBER 17, 1981 On December 17, 1981, a meeting was held in Bethesda, Maryland, between the NRC staff and representatives of the BWR Owners' Group and their consultants to discuss the subject of in-core thennocouples for BWRs. An attendance list for the meeting is provided as Enclosure 1.
Mr. T. Dente, Chainnan of the Owners' Groun, infonned us that on this subject the group respresents all BWRs, both operating reactors and those reactors under licensing review.
Mr. J. C. Gillis of S. Levy, Inc., made a presentation on work that his company had performed under contract to the Owners' Group.
The objective of the work was to address the response of in-core thermocouples to low coolant level and to estimate the cost in money and radiation exposure for installation and maintenance of the thermocouples.
Depending on the specific situation, it was estimated that installation costs would vary between $1.7 and $2.5 million, and that the radiation exposure would vary between 65 and 450 man-rem.
The most practical location to install thermocouples in a BWR is in the power range monitor (PRM) instrument assemblies.
In addition to locating the thermocouples in the PRMs, Levy Inc. investigated locating the thermocouples in the reactor upper plenum directly above the core and in the steam dome.
In all locations, Levy concluded that the thermocouples would not provide prompt response.
Furthermore, Levy stated that if water is being supplied to the core, the thermocouples would rewet and cool.
In this situation, they might give an incorrect indication of the actual local condition within the core.
Mr. C. Reed of Comonwealth Edison summed up the Levy Inc. work for the Owners' Group by stating that evidence indicates that the thermocouples are not an accurate means of providino the diagnostic performance for monitoring inadequate core cooling and degraded core conditions that NRC desires.
A brief presentation was made by General Electric Co. that sumarized a risk analysis performed utilizing in-core thermocouples.
A sumary of the GE presentation is attached as Enclosure 2.
GE aenerated event ant' fault trees for identifiable accident sequences.
Based on the results of this analysis, GE concludes that thermocouples provide a negligible benefit or, core melt probability and radiation exposure to the public while incurring both a monetary and'an occunational exposure cost.
Therefore, a cost benefit evaluation does not justify utilizing thermocouples in BWRs.
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. The staff indicated that the quickness of response (in minutes) and the accuracy of the instruments (a few degrees) are not vitally important.
The key item is a need for diverse indication of the status of the core if water level is lost for any reason. This is a broader concern than simply placing thermocouples in BWRs. Thermocouples were an immediate possibility that people considered when addressing this concern initially.
However, it is not thermocouples that the staff necessarily desires, but rather a means of accurate and reliable indication of the core environment beyond design basis accident condition.
R. Mattson identified a potential problem associated with water level indication in BWRs.
For many accident situations such as the entire spectrum of LOCA's, the reference leg of the water level indicators may flash to steam and the indicators are likely to fail. The extent of this problem depends upon the location of the reference leg.
It is the staff's understanding that the location may be different in different reactors.
Related to this problem of level indication is a concern about the existence and availability of operating procedures for such situations.
For operating reactors, are procedures identified for this situation and are the operators trained for such circumstances? Since this is a relatively recent concern within the staff, internal discussions are underway regarding the scope and implications of the flashing problem and the l
reliability of water level instrumentation.
During the period of staff review, the Owners' Group and GE are encouraged to review the situation themselves in preparation for further dialoque n the subject.
With regard to the requirement for thermocouples in BWRs, the staff agreed to reconsider this issue in light of the arguments presented at the meeting by GE and S. Levy, Inc. Since thermocouples are required by Reg. Guide 197, and are a stated condition in current licensing safety evaluation such as LaSalle and Grand Gulf, the staff may have to adjust these requirements based on the results of continuing evaluation.
However, in addition to thermo-couples, the staff identified, clearly, a need for diverse means of indicating inadequate core cooling.
The Owners' Group agreed to suqqest to their respective managements that their task be redirected to this broader issue.
Mr. Denton suggested that the industry consider the infonnation presented and discussed at the l
meeting, and propose an action plan addressing industry efforts in response to these concerns in about 30 days. Mr. Denton indicated the importance of prompt attention to the problem in lioht of near term licensing schedules.
D 4 s c;q;g 3y, H. J. Faulkner, Project Manager Standardization and Special Projects Branch Division of Licensing 4
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s gv JAN 2 71982 MEMORANDUM FOR:
James R. Miller, Chief Standardization & Special Projects Branch Division of Licensing FROM:
H. J. Faulkner, Project Manager Standardization & Special Projects Branch
SUBJECT:
SUMMARY
OF MEETING WITH 3WR OWNERS' GROUP ON DECEMBER 17, 1981 On December 17, 1981, a meeting was held in Bethesda, Maryland, between the NRC staff and representatives of the BWR Owners' Group and their consultants to discuss the subject of in-core thermocouples for BWRs. An attendance list for the meeting is provided as Enclosure 1.
Mr. T. Dente, Chairman of the Owners' Group, informed us that on this subject the group respresents all BWRs, both operating reactors and those reactors under licensing review.
Mr. J. C. Gillis of S. Levy, Inc., made a presentation on work that his company had performed under contract to the Owners' Group.
The objective of the work was to address the response of in-core thermocouples to low coolant level and to estimate the cost in money and radiation exposure for installation and maintenance of the thermocouples.
Decending on the specific situation, it was estimated that installation costs would vary between $1.7 and $2.5 million, and that the radiation exposure would vary between 65 and 450 man-rem. The most practical location to install thermocouples in a BWR is in the power range monitor (PRM) instrument assemblies.
In addition to locating the thermocouples in the PRMs, Levy Inc. investigated locating the thermocouples in the reactor upper plenum directly above the core and in the steam dome.
In all locations, Levy concluded that the thermocouples would not provide prompt response.
Furthermore, Levy stated that if water
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is being supplied to the core, the thermocouples would rewet and cool.
In this situation, they might give an incorrect indication of the actual local condition within the core. Mr. C. Reed of Commorwealth Edison summed up the Levy Inc. work for the Owners' Group by stating that evidence indicates that the thermocouples are not an accurate means of providing the diagnostic performance for monitoring inadequate core cooling and degraded core conditions that NRC desires.
A brief presentation was made by General Electric Co. that sumarized a risk analysis performed utilizing in-core thermocouples. A summary of the GE presentation is attached as Enclosure 2.
GE generated event and fault trees for identifiable accident sequences.
Based on the results of this analysis, GE concludes that thermocouoles provide a negligible benefit on core melt probability and radiation exposure to the public while incurring both a monetary and an occupational exposure cost. Therefore, a cost benefit evaluation does not justify utilizing thermocouples in BWRs.
l l
' p 2 71987.
The staff indicated that the quickness of response (in minutes) and the accuracy of the instruments (a few degrees) are not vitally important.
The key item is a need for diverse indication of the status of the core if water level is lost for any reason. This is a broader concern than simply placing thermocouples in BWRs.
Thermocouples were an immediate possibility that people considered when addressing this concern initially.
However, it is not thermocouples that the staff necessarily desires, but rather a means of accurate and reliable indication of the core environment beyond design basic accident conditions, l
R. Mattson identified a potential problem associated with water level indication in BWRs.
For many accident situations such as the entire spectrum of LOCA's, the reference leg of the water level indicators may flash to steam and the indicators are likely to fail.
The extent of this problem depends upon the location of the reference leg.
It is the staff's understanding that the location may be different in different reactors.
Related to this problem of level indication is a concern about the existence and availability of operating procedures for such situations.
For operating reactors, are procedures identified for this situation and are the operators trained for such circumstances? Since this is a relatively recent concern within the staff, internal discussions are underway regarding the scope and implications of the flashing problem and the reliability of water level instrumentation.
During the period of staff review, the Owners' Group and GE are encouraged to review the situation themselves in preparation for further dialogue on the subject.
With regard to the requirement for thermocouples in BWRs, the staff agreed to reconsider this issue in light of the arguments presented at the meeting by GE and S. Levy, Inc. Since thermocouples are required by Reg. Guide 197, and are a stated condition in current licensing safety evaluation such as LaSalle and Grand Gulf, the staff may have to adjust these requirements ba5ed on the results of continuing evaluation. However, in addition to thermo-couples, the staff identified, clearly, a need for diverse means of indicating inadequate core cooling.
The Owners' Group agreed to suggest to their respectise managements that their task be redirected to this broader issue.
Mr. Denton suggested that the industry consider the information presented and discussed at the meeting, and propose an action plan addressing industry efforts in response to these concerns in about 30 days. Mr. Denton indicated the importance of prompt attention to the problem in light of near term licensing schedules.
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H. J.
aulkner, Project Manager Standardization and Special Projects Branch Division of Licensing
Enclosures:
Attendance List GE Risk Analysis cc: See Distribution Page
i Attendance BWR In-Core Thermocouples Name Organization H. Denton NRR R. Mattson DSI/NRR E. Case NRR H. Faulkner DL/NRR C. H. Berlinger NRR/CPB R. S. Boyd KMC/LRG E. G. Case NRR J. C. Gillis S. Levy, Inc.
R. St. Owge Boston Edison CO.
P. Powell Washington Public Power Supply System S. Levy S. Levy, Inc.
W. F. Col bert Detroit Edison L. E. Schuerman Detroit Edison D. J. Robare General Electric Co.
L. O. DelGeorge Commonwealth Edison M. W. Hodges NRR/RSB J. E. Rosenthal NRR/ICSB J. L. Smith Long Island Lighting Co.
B. Grunseich Long Island Lighting Co.
D. Wilkinson EPRI/NSAC A. Schwencer LB#2/DL/NRR R. L. Tedesco NRR/DL R. A. Hill General Electric Co.
C. T. Coddington Pennsylvania Power & Light Co.
J. Wilson NRC/DL S. H. Hanauer NRC/ DST R. A. Purple NRR/DL L. Phillips NRR/DSI/CPB L. S. Rubenstein NRR/CPC Y. Balas IELP/ Chair R. G.1.97 Committee G. D. Bouchey Washington Public Power Supply System G. Sherwood General Electric Com N. W. Curtis Pa. Power & Light Co.
C. Reed Commonweal th Edison T. Dente Northeast Utilities
.