ML20125D658
| ML20125D658 | |
| Person / Time | |
|---|---|
| Site: | Millstone, Hatch, Monticello, Dresden, Peach Bottom, Browns Ferry, Nine Mile Point, Fermi, Oyster Creek, Hope Creek, Cooper, Pilgrim, Brunswick, Vermont Yankee, Duane Arnold, Quad Cities, FitzPatrick |
| Issue date: | 08/18/1976 |
| From: | Gueibert J Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9212150349 | |
| Download: ML20125D658 (12) | |
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- [, UNITED STATES
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'~'rD WASHING TON, D. C. 20668 AUG1 6 hi/6 DOCKETS NOS.:
50-219, 50-220,' 50-237, 50-245, <50 249, 50-254,/50-250, 50-260/58463,50-265,.50-271,50-277,50-278v50-293, 50-296,'50-298, 50-321,'50-324, 50-325,',50-331, 50-333, ',
50-341', 50-354, 50-355, and 50-366. '
LICENSEES:
Boston Edison Company, Carolina Power & Light Company, Commonwealth Edison Company, Detroit Edison Company Georgia Power Company, Iowa Electric Light & Power Company,, Jersey Central Power & Light Company, Nebraska Public Power District, Niagara Mohawk Power Company, Northeast Nuclear Energy Company, Northern States Power Company, Philadelphia Electric Company, Power Authority of the State of New York, Public Service Electric and Gas, Tennessee Valley Authority, Vemont Yankee Nuclear Power Corporation.
FACILITIES:
Oyster Creek Nuclear Generating Station, Nine Mile Point Unit 1. Pilgrim 1 Dresden Units 2 and 3. Millstone Unit
- 1. Quad Cities Units 1 and 2, Monticello, Peach Bottom Units 2 and 3. Browns Ferry Unit 1, 2 and 3. Vermont Yankee, Hatch Units 1 and 2 Brunswick Units 1 and 2 Quane Arnold Energy Center, Cooper, Fitzpatrick, Enrico Fermi Unit 2, and Hope Creek Units 1 and 2.
MARK I OWNER'S GR0llP
SUMMARY
OF MEETINGS HELD ON JULY 7 AND On July 7 and 8,1976 meetings were held in Bethesda with representatives of the Mark I Owner's Group, General Electric Company, and their technical consultants.
The purpose of the meetings was to discuss .
content of the Mark I Containment Long Term Program (LTP)(, and (2) the1) t .
recentlyFinal Program submitted responses to the NRC staff's questions on the Short Term Report (STPFR).
attendees. Enclosures 1 and 2 are lists of the meeting JULY 7, 1976 MEETING Group, stated that the Owner's Group was prepared to d ,
program for several elements elements included in the reassessed LTP in general terms but that, detailed descriptions are not yet available.
expressed a desire on, the part of the Owner's GroupHeto schedule anoth a meeting in thepresented the information near future today. to obtain NRC staff coments and reactions to' .
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R. Buchholz and P. Ianni, General Electric Company, presented a description of the LTP tasks and objectives, including the anticipated schedule for completion of the integrated LTP and its various program elements. They stated that a " Program Action Plan" would be submitted to the NRC staff in September 1976 which would describe and document the LTP tasks and objectives. In general, the major LTP scheduling milestones which were presented are as follows:
September 1976 Program Action Plan submitted to NRC March 1977 Preliminary Load Evaluation Report prepared liay 1977 Composite Plant Evaluation completed July 1978 Load Definition Report submitted to NRC The GE representatives further stated that the Load Definition Report would be used for the perfonnance of plant-unique structural analyses for each Mark I facility. Facility modifications, if necessary, would te scheduled for completion during subsequent refueling outages for the affected facilities. Enclosure 3 contains the slides used in their presentation.
Enclosure 4 consists of supplemental information.
The NRC staff expressed the following concerns during discussions of the proposed LTP:
- 1. The NRC staff should be informed of the schedule for planned testing during the LTP for enough in advance to assure opportunities for discussions with the Owner's Group.
- 2. The NRC staff expressed concern that the LTP, as presented, is open-ended with no established completion date. D. Galle stated that the plant-unique analyses would be submitted approximately six months after the completion of the Load Definition Report and that required modifications would be accomplished within the time period encompassing the next two rr'ueling outages. The NRC staff stated that the Owner's Group should make every effort to expedite the LTP.
- 3. The NRC staff stated that the adequacy of the Safety-Relief Valve (SRV) piping restraints in the drywell to withstand the SRV loads identified in the LTP should be addressed by each Mark I licensee as a part of the LTP.
- 4. The NRC staff stated that the need for further testing of vent pipe bellows should be investigated as more refined loading information
.j becomes available.
.[pl 5 The NRC staff expressed concern that etforts related to the devel-
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opment of the LTP Structural Acceptance Criteria were not proceeding at a pace which would assure completion as scheduled.
- 6. The NRC staff stated that hydrodynamic / structural interactions and the resulting potential for load magnification should be investigated in the LTP.
7, The NRC staff stated that further infonnation on several items related to the LTP is required prior to the completion of the STP. For each of these items (most of wMch were identified during the meeting) the NRC staff requested that the Mark I Owner's Group describe: (1) the LTP program action plan under which the concern will be addressed (2) the method or technique which will be utilized in addressing the concern, and (3) at what point in time during the LTP that the concern will be addressed. The NRC staff agreed to provide the Mark I Owner's Group a listing of the abovementioned items as soon as possible.
At the conclus1on of the meeting it was agreed that another meeting should be scheduled during the third week of August to continue the discussions on the LTp. In addition, it was agreed that a separate meeting would be scheduled in early August to discuss certain LTP testing programs.
JULY 8, 1976 MEETING Meetings were held to discuss the responses submitted by the Mark I Owners to the NRC staff's questions on the STP Final Report. Separate meetings were held to discuss questions related to hydrodynamic loads and structural concerns.
Hydrodynamic Loads ListedbelowaretheNRCstaffconcernsraisedatthismeetingandthe responses supplied by the representatives of the Mark I Owner s Group:
- 1. NRC concern: Data from the 1/12th scale tests indicated higher ring header impulse loads than the Pressure Suppression Test Facility (PSTF) impact data that was used for the ringheader structural analysis and the detennination of uplift. The test report concluded that the higher ring header impulse loads were probably a combination of i downcomer drag and the superposition of bubble pressure I on the water momentum.' 4 Response: Although the measured impulse loads were higher, the duration was longer such that the peak impact load, as '
detennined by PSTF, is conservative. GE indicated that the 1/4 scale tests will provide additional data for j the ringheader in conjunction with the flexible cylinder testing program for the ringheader.
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- 2. NRC concerni It was pointed out that the method used to detemine the torus loads as a function of the plant unique water mass was a judgment technique which has no theoretical basis.
GE was asked what provisions had been made in the long-y tem program (LTP) to confim this assumption.
q, Response: GE indicated that no provisions had been made in the LTP to confinn load variation with plant unique water mass however, this will be addressed in the LTP along with the The LTP currently other plant unique sensitivity factors.
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' plans to provide plant unique loads from a three dimensional analytical model which will be confirmed by comparison to data.
- 3. NRC concern: GE was asked to clarify the suspected cause for the differences observed in the downward loads between the December 1975 and January 1976 test series.
Response: Between the December and January tests the test facility was disassembled and reassembled with grouting added to
' the base mat. No other changes were made to the test facility during that time. GE believes that improper reassembly of the facility may have resulted in bending of the side windows. Additional accelerometers will be added for the LTP 1/12th tests to verify this hypothesis. Since the higher loads were observed in only 3 out of approximately 13 test runs, they are considered an anomaly. However, the higher loads are reflected in the load sensitivity factors for differential pressure control.
- 4. NRC concern: Addendum 2 to the STP Final Report discusses the interpolation of data for the large and medium blowdown orifices to match the drywell pressurization rate for the reference plant. GE was asked to clarify this interpolation technique.
For the LTP GE should consider trying to achieve a better match, for both the drywell pressurization and the enthalpy flux, between the measured values and the scaled reference values. In this . regard, the frictional losses (f1/d), while conservative for the drywell pressure calculation, may lead to deviations in the enthalpy flux for the test conditions.
Response: GE indicated that interpolation factors were calculated as a function of time to adjust the data to the reference case.
The consnents made on the LTP will be addressed during the program.
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5-S. NRC concern: GE was asked to clarify the basis used to classify chugging loads on the torus walls as a secondary load, since some significant loads are reported in fortegn test data.
Response: The torus chugging loads for Mark I's are considered as low magnitude loads relative to the primary loads and also out of phase (i.e., occurring later in time). In addition, 1 chugging is a fatigue load, rather than an impulsive load, and thereforc is not as significant with regard to structural capabiltty. -
- 6. NRC concern: The load sumary, presented in response to the STP questions, indicates a value of + 2 feet for post swell waves. Clarification was requested regarding the STP load magnitude for slosh and waves. ,
Response: Both post swell waves and seismic slosh have been classified as secondary loads based on their low relative magnitudes.
Consequently, no load has been specified for the STP.
- 7. NRC concern: Load combination histories, provided in a response to the
> STP questions, indicate the timing of specific loads in a very general manner. GE was asked how the timing of loads is detemined for a plant unique analysis.
Response: The specific timing for each load is given as part of the load definition in Addendum 2 to NEDC 20989P.
- 8. NRC concern: GE was asked to clarify the manner by which three dimensional crossflow velocities were detemined to compute submerged drog.
Response: The crossflow velocities.were determined from observations of the 1/12th-scale test films. Bubble prapagation at various distances from the downcomer exit were used to establish pool velocity. For submerged structures located on lines of symetry, the two dimensional bubble propagation between downcomers was-used.
, 9. NRC concern: Responses to the STP indicate that the water' jets, as observed in the 1/12 test films. impinging on the upper i torus shell, are conservatively evaluated by using the froth loading. . However, for the torus uplift evaluations the froth load has been neglected in the loading combination.
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I Response: Minimal water jet formation was observed in the base case 1/12th films after the scaling had been corrected. On !
this basis, the froth load was neglected in the load j
combinations for the plant unique analyses. The froth -i Ioad was used in the structural screening analysis for .
torus integrity. In the LTP, a bounding value for the ,
- upward water jet load will be established.
s i 10. NRC concern: The following additional points of-clarification were discussed:
- a. The EPRI 1/10th scale based pool velocity was ,
not updated in the load definition because the value 2 used was fairly represenative of the 1/12th test results and would not, therefore, significantly _
change the loads.
- b. All of the component _ evaluations used impact and drag loads except for the monorail.and spray header. '
There are no plans to update volume IV of the STP Final Report to reflect this,
- c. Nine Mile Point is the only plant that has any solid or checker plate in any of the catwalk sections.
Structural Concerns ,
I During discussions with representatives.of the Mark I Owner's Group on i their responses to the NRC staff's questions of December 24, 1975, the NRC l staff identified the following items which require further documented i information by September 1,1976:
- 1. The response to question MEB-5 should biclarified to explain how
- the energy-absorption capability of the downcomers was detennined.
In addition, the basis for the 1.6 KIP sideload on the downcomers due to seismic slosh should be provided.
- 2. The response to question SEB-la should be clarified to describe L the methods used for considering horizontal seismic loads.
- . 3. The response to question SEB-lb should be expanded to demonstrate
> -that the allowable strain on the vent header assures a safety factor of two for that element.
t 4. The response 'o question SEB-1c should be expanded to provide clarification tnat the submerged drag loads on the vent header support columns were combined with.the primary loads. In addition.
a general statement on the maximum effects of secondary loads-should be provided.
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- 5. The response to question SEB-2 should include a statement on vent header yielding.
- 6. The response to question.SEB-3 shorld be expanded to provide an explanation of why multiple testing was not performed.
- 7. The response to question SEB-6 shouhi be expanded to provide information on " experience" with Safety-Relief valve loads.
B. The response to question SEB-8 should be expanded to provide an explanation of why no local yielding would occur on the torus shell.
- 9. With respect to the first part of question SEB-10. a plant unique assessment of this concern is required.
- 10. The response to question SEB-17 should be expanded to include a discussion of potential strain combination effects due to yielding from (1) pool swell loads and-(2) lateral loads.
- 11. The response to question SEB-18 should be expanded to provide a concluding statement.
In addition to the foregoing, the NRC staff stated that responses to those questions which were identified as requiring a plant-unique response must be provided either in conjunction with the submittal of the plant '
unique structural analyses or by September 1.1976. The staff also expressed its desire that the STP Final Report be updated to reflect the new information which has developed since September 1975.
(oadMitigatingTesting B. Petrokas NUTECH, presented infonnation related to preliminary load mitigation testing efforts which are currently in progress. He provided narration for a film which showed testing efforts on 12 of the 18 experimental downcomer devices which are being investigated as possible pool swell load '
mitigating devices. These testing efforts represent the initial screening /
process for such devices. The Mark I Owner's Group stated that they would continue study. to keep the NRC staff advised of their efforts in this continuing l
J hn C. Guibert Operating Reactors Branch #3 Division of Operating Reactors
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.j NUCLEAR REGULATORY cOMMisslON W AsHINGTON, 0. C. 20655 I / AUG1 6 W6 g .m..../
DOCKETS NOS.: 50-219, 50-220, 50-237, 50-245, 50-249, 50-254, 50-259 -
50-260,5Ff63,50-265,50-271,50-277,50-278,50-293, 50-296, 50-298, 50-321, 50-324, 50-325, 50-331, 50-333, 50-341, 50-354, 50-355, and 50-366.
LICENSEES: Boston Edison Company, Carolina Power a Light Company.
Commonwealth Edison company, Detroit Edison Company, Georgia Power Company. Iowa Electric Light & Power Company, Jersey Central Power & Light Company, Nebraska Public. Power District, Niagara Mohawk Power Company, Northeast Nuclear -
Energy Company, Northern States Power Company Philadelphia Electric Company, Power Authority of the State of New York, !
Public Service Electric and Gas, Tennessee Valley Authority, Yemont Yankee Nuclear Power Corporation.
FACILITIES: Oyster Creek _ Nuclear Generating Station, Nine Mile Point Unit 1. Pilgrim 1. Dresden Units 2 and 3. Millstone Unit
- 1. Quad Cities Units 1 and 2. Monticello, Peach Bottom Units 2 and 3. Browns Ferry Unit 1, 2 and 3. Vermont Yankee, Hatch Units 1 and 2, Brunswick Units 1 and 2 Duane Arnold Energy Center, Cooper Fitzpatrick Enrico Fermi Unit 2, and Hope Creek Units 1 and 2.
SUMMARY
OF MEETINGS HELD ON JULY 7 AND 8, .1976 WITH REPRESENTATIVES OF THE MARK I OWNER'S GROUP On July 7 and 8,1976 meetings were held in Bethesda with representatives of the Mark I Owner's Group, General Electric Company. and their technical
( consultants. The purpose of- the meetings was to discuss (1). the reassessed content of the Mark I Containment Long Term Program (LTP), and (2) the recently submitted responses to the NRC staff's questions on the-Short Tenn Program attendees.
Final Report (STPFR). Enclosures-1 and 2 are lists of the meeting JULY 7, 1976 MEETING D. Galle, Commonwealth Edison Company and Chairman of the Mark I Owner's -
Group, stated that the Owner's-Group was prepared to discuss all of the program elements included in the reassessed LTP in general terms but that, for several elements, detailed descriptions;are not yet available. He expressed a desire on the part of the Owner's Group to schedule ancther -
meeting in the near future to obtain NRC staff coments and-reactions- to
, ~ the _information presented today.
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.- . ,3, opment of the LTP Structural Acceptance Criteria were not proceeding at a pace which would assure completion as scheduled.
The NRC staff stated that hydrodynamic / structural interactions and 6.
the resulting potential for load magnification should be investigated in the LTP,
- 7. The NRC staff stated that further infonnation on several items related to the LTP is required prior to the completion of the STP. Foreachoftheseitems(mostofwhichwereidentifiedduring the NRC staff requested that the Mark I Owner's Group the meeting)(1) the LTP program action plan under which the concern describe:
will be addressed (2) the method or technique which will be utilized in addressing the concern, and (3) at what point in time during the LTP that the concern will be addressed. The NRC staff agreed to provide the Mark I Owner's Group a listing of the abovementioned items as soon as possible.
At the conclusion of the meeting it was agreed that another meeting should be scheduled during the third week of August to continue the discussions on the LTP. In addition, it was agreed that a separate meeting would be scheduled in early August to discuss certain LTP testing programs, JULY 8. 1976 MEETING Meetings were held to discuss the responses submitted by the Mark I Owners to the NRC staff's questions on the STP Final Report. Separate meetings were held to discuss questions related to hydrodynamic loads and structural Concerns.
Hydrodynamic loads l Listed below are the NRC staff concerns raised at this meeting and the
' responses supplied by the representatives of the Mark I Owner s Group:
- 1. NRC concern: Data from the 1/12th scale tests indicated higher ring header impulse loads than the Pressure Suppression Test l
Facility (PSTF) impact data that was used for the ringheader structural analysis and the determination of uplift. The test report concluded that the higher ring header impulse loads were probably a combination of downcomer drag and the superposition of bubble pressure on the water momentum, i
Response: Although the measured impulse loads were higher, the duration was longer such that the peak impact load, as detennined by PSTF, is conservative. GE indicated that the 1/4 scale tests will provide additional data for the ringheader in conjunction with the flexible cylinder-j testing program for the ringheader.
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- 2. NRC concern:
It was pointed out that the method used to detemine the i
torus loads as a function of the plant unique water mass was a judgment technique which has n; theoretical basis.
GE was asked what provisions had been made in the long-tem program (LTP) to confim this assumption, Response: GE indicated that no provisions had been made in the LTP f to confim load variation with plant unique water mass; ,
i however, this will be addressed in the LTP along with the other plant unique sensitivity factors.- The LTP currently plans to provide plant unique loads from a threedimen
+
comparison to data.
I GE was asked to clarify the suspected cause for the differences l 3. NRC concern:
observed in the downward loads between the December 1975 ~
and January 1976 test series.
j Response: Between the December and January tests the test facility was disassembled and reassembled with grouting added to the base mat. No other changes were made to the test facility during that time. GE believes- that improper reassembly of the facility may have resulted in bending of the side windows. Additional accelerometers will be added for the LTP 1/12th tests to verify this hypothesis. Since
- the higher loads were observed in only 3 out of approximately
-13 test runs, they are considered an anomaly. However, '
the higher loads are reflected in the load sensitivity factors
, for differential pressure control.
- 4. NRC concern:
Addendum 2 to the STP Final Report discusses the interpolation of data for the large and medium blowdown orifices to 3 match the drywell pressurization rate for the reference i
' plant. GE was asked to clarify this interpolation technique.
1 For the LTP GE should consider trying to achieve a better 4
match, for both the drywell pressurization and the enthalpy flux, between the measured values and the scaled reference
- values. In this regard, the frictional losses (f1/d), while conservative for the drywell pressure calculation, may-lead to deviations in the enthalpy flux for the test conditions.
Response: GE indicated that interpolation factors were-calculated as a function of time to adjust the data to the reference case.
The comments made on the LTP will be addressed during the program.
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- 5. NRC concern: GE was asked to clarify the basis used to classify chugging loads on the torus walls as a secondary load, since some significant loads are reported in fortegn test data.
Response: The torus chugging loads for Mark I's are considered as low magnitude loads relative to the primary loads and also In addition, out of phase (i.e., occurring later in time).
chugging is a fatigue load, rather than an impulsive load, and therefore is not as significant with regard to structural capability.
- 6. NRC concern: The load sumary, presented in response to the STP questions, indicates a value of 12 feet for post swell waves. Clarification was requested regarding the STP load magnitude for slosh and waves.
Response: Both post swell waves and seismic slosh have been classified as secondary loads based on their low relative magnitudes.
Consequently, no load has been specified for the STP.
- 7. NRC concern: Load combination histories, provided in a response to the STP questions, indicate the timing of specific loads in a very general manner. GE was asked how the timing of loads is determined for a plant unique analysis.
Response: The specific timing for each load is given as part of the load definition in Addendum 2 to NEDC 20989P.
- 8. NRC concern: GE was asked to clarify the manner by which three dimensional crossflow velocities were determined to compute submerged drog.
Response: The crossflow velocities were determined from observations of the 1/12th scale test films. Bubble prapagation at va' lous distances from the downcomer exit were used to establish pool velocity. For submerged structures located on lines of symetry, the two dimensional bubble propagation between downcomers was used.
- 9. NRC concern: Responses to the STP indicate that the water jets, as observed in the 1/12 test films, impinging on the upper torus shell, are conservatively evaluated by using the froth loading. However, for the torus uplif t evaluations the froth load has been neglected in the loading combination.
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6-Response: Minimal water jet fomation was observed in the base case .
1/12th films af ter the scaling had been corrected. On this basis, the froth load was neglected in the load l combinations for the plant unique analyses. The froth load was used in the structural screening analysis for torus integrity. In the LTP, a bounding value for the !
i upward water jet load will be established.
- 10. NRC concern: The following additional points of clarification were discussed:
- a. The LPRI 1/10th scale based pool velocity was not updated in the load definition because the value ,
used was fairly represenative of the 1/12th test results and would not, therefore, significantly change the loads.
- b. All of the component evaluations used impact and drag loads except for the monorail and spray header.
There are no plans to update volume IV of the STP Final Report to_ reflect this.
- c. Nine Mile Point is the only plant that has any solid or checker plate in any of the catwalk sections.
Structural Concerns During discussions with representatives of the Mark I Owner's Group on ;
their responses to the NRC staff's questions of December 24. 1975, the NRC staff identified the following items which require further documented information by September 1, 1976:
- 1. The response to question MEB-5 should be clarified to explain how the energy-absorption capability of the downcomers was determined.
In addition, the basis for the 1.6 KIP sideload on the downcomers due to seismic slosh should be provided.
- 2. The response to question SEB-la should be clarified to describe the methods used for considering horizontal seismic loads.
- 3. The response to question SEB-1b should be expanded to demonstrate that the allowable strain on-the vent header assures a safety factor of two for that element.
- 4. The response to question SEB-1c should be expanded to provide clarification that the submerged drag loads on the vent header support columns were combined with the primary loads. In addition, a general statement on the maximum effects of secondary loads should be provided, t' l #
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