ML072830329
| ML072830329 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 03/30/2006 |
| From: | - No Known Affiliation |
| To: | Office of Nuclear Reactor Regulation |
| SECY RAS | |
| References | |
| 50-219-LR, AmerGen-Intervenor-3, OCLR00014708, RAS 14303 AR 00461639 | |
| Download: ML072830329 (4) | |
Text
Cz5 Ehb303 Citizens Exhibits
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AR 00461639 Report Aft Fain Oyster Creekl AR Type:
CR Status:
APPROVED Aft Unit:
01 Owed To, A5352CAP Due Date:
06/30/2006 Aft System; 187 Event Date 03/03/2006 CA Level/Class:
4/D Disc Date:
03/0312006 How Discovered: H02 Orig Dale:
03/0312006 0 tot WRIPIMS AR:
Componeant #:
CFIl A..n
.s RU Action Request Wealls IDJI DOCKETED USNRC er 1,2007 (10:45am)
CE OF SECRETARY LEMAKINGS AND UDICATIONS STAFF CALC C-i302-187-5320-024 IS NOT CLEARLY DOCUMENTED
Subject:
Desciption:
Originator: PETER TAMBURAO Supv Contacted: Howle Ray Condition Desciption:
Operability Evaluation, The Oyster Creek Drywell Vessel is capable of performing all it design basis functions. The deficiency raises concerns with the clarity of the calculatJon and not with i[s conclusions.
Calculation C-1302-187-5320-024 Is the Only Safety Related calculation that demonstrates that the 1992 as left Drywell Vessel thicknesses In the former Sandbod region meets design basis. Drywell Vessel Thickness was measured by visual, mechanical and UT inspection after sand and corrosion byproducts were removed but prior to coating application, In general this calculation does notmeast the requirements of CC-AA-309-1001 Section 4.1.3 which has the following requirements:
Provide analysis sufficiently detailed as to purpose, method, assumptions, design input, references and units, such that a person technically qualified In the subject can review and understand the analysis and verify the adequacy of the results without recourse to the originator.
Please note this calculation was generated under the GPUN Calculation Procedure EP-00. However this GPLIN procedure contained the same requirement.
For example; four qualified Engineers with at least 15 years experience.
reviewed this calculation, None could clearly underrtand how the calculation methodology and acceptance criteria demonstrate the conduslons of the calculations.
Given that this calculation provides design basis for Drywetl Vessel thickness In the-former Sandbed region It Is recommended Engineering revise this. calculation so that it can be clearly understood.
The following are specific deficiencies with this calculation Item I -
The measured DryweUl Vessel thickness Inputs for this calculation are not properly documented and traceable to the original NDE Data Sheets, The thickness values are reproduced in the calculation but there Is no reference to the original data 5heets, which documented the Inspection results. This deficiency does not meet CC-AA-309 Step 4,3.1 and CC-AA-309-1001 and CC-AA-309-1001 Sectlons: 4.1.3 and 4.3.7. please note this calculation was generated under the GPUN Calculation Procedure EP-O06. However this GPUN procedure contained the same requirement.
Item 2 -
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'g 2o e-agez al 5 The calculation does not provide a methodology section that documents how the calculation is performed. The methodology Is barely described In the calculation section. This deficiency does not meet CC-AAn309 Step 4.3a i and CC-AA-309-to01 Sections. 4b1.3 and 4.3.7. mease note this calculation was generated under the GPUN Calculation Procedure EP-006. However this GPUN procedure contained the same requiremeriL Item 3 -
The calculation develops a tarm called evaluation thickness based on actual measured thicknesses. This value is then compared to the design basis minimum required uniform thickness for the sandbed region of 0.736.
The method In which evaluation thickness Is developed Is poorly explained.
in addton the Justilfication as to why It is acceptable to compare the evaluation thickness to the design basis required minimum uniform thickness of 0.736 is not documehted In the calculation nor is there a reference to an Industry standard.
Item 4 -
The calculation uses a Local Wall Acceptance Criteria. This criteria was developed by GE and IS referenced in the calculation, The criteria can be applied to a small area (less thin 12 by 12), which are less than 0.736 thick so long as the small area is at least 0.536 thick. In develaping the criteria GM developed an ANSYS model of the Drywall Vessel. The model Included a 12 by 12 area that was 0.536 thick at the weakest location (with respect to buckling) of the drywll. The12 by 12 area was then surrounded by a larger 24 by 24ares that trensitloned from 0.536 to 0.736, The remaining thickness of the Drywall Vessel was then modeled at a uniform thickness of 0.736, Both the Ga referenced report and calculation C-1302-187-5320-024 State that in this case the ultimate theoretical buckling capacity of the dryWweU vessel shell Is reduced by 9,5%, Calculation C-1302-187-5320-024 contains no statement or justification that a 9.5% reduction In budkling load still meets code allowables.
Item 5 -
The calculation uses a Local Wail Acceptance Criteria. This criteria can be applied to small areas (less than 12 by 12), which are less than 0.736 thick so long as the small 12 by 12 area Is at least 0.536., however the calculation does not provide additional criteria as to the acceptable distance between multiple small areas. For example, what Is the minimum required linear distances between a 12 by 12 area thinner than 0.736 but thicker than 0.536 and another 12 by 12 area thinner than 0.736 but thicker than 0.536.
The actual data for two bays (13 and 1) shows that there are more than one 12 by 12 areas thinner than 0.736 but thicker than 0.536, Item 6 -
The calculation uses a Very Local Wall Acceptance Criteria. This criteria can be applied to small areas (less than 2 1/2 In diameter), which are less then 0.736 thick so long as the very small area Is at least 0.49 thick and remaining area surrounding the very small area has a uniform thickness at greater than 0.736. However the calculation does "dt provide additional criteria as to the acceptable distance between multiple very small areas. For example what is the minimum required linear distances between a 2 diameter area thinner than 0.736 but thicker than 0.49 and another 2 diameter area thinner than 0.736 but thicker than 0,49.
The actual data for two bay (13 and 1) shows that there are more than one 2 diameter areas thinner than 0.736 but thicker than 0.490.
Item 7 -
the calculation uses a Very Local Wall Acceptance Criteria. This criteria can be applied to small areas (less than 2 1/2 In diameter); which are thinner than 0.736 thick so long as the very small area Is at least 0.49 thick and remaining area surrounding the very small area has a uniform hntpJ/cccmvdOl.eeco.com6123/caplservletiReporLARServ]et 5/30/2006 OCLR00014709
-Assignment Ke-porE rage i or thickness of greater than 0.736.
The criteria was obtained from a second calculation (C-1302-24-5320-071),
which Is referenced. However C-1302-24-5320-071 does a poor job of developing the basis of the criLeria and does not state whether the 0.49 criterla Is acceptable for buckding loads.
Item 8 -
Calculation Section 5 Sub Section Bay 1 documents that there are 8 small areas In Bay 1 all less than 2 1/2 diameter, thinner than 0.736 but thicker than 0.536. These 8 small areas are scattered In a larger area, which Is approximately 25 wide and 50 long. The calculation then selects 2 of the small areas ther are dosest together and combines these into a 4 by 4 area. The thickness of this 4 by 4 area is then compared to the Local Wall Acceptance Criteria, which is applicable for area up to 12 by
- 12. The small 4 by 4 area then Is judged to be the bounding area for the larger 25 by 50 area. This Is then used as justification that the larger 25 by SO area is acceptable.
However, the calculation does not reconcile between the established criteria, for a 12 by 1.2 area, and the actual data, which has areas thinner than 0.736 scattered over a 25 by 50 area.
Item 9 -
Calculation Section S Sub Section Say I documents that there are 8 small areas in Bay 1 all less than 2 1/2 diameter, thinner than 0.736 but thicker than 0,535. These 8 small areas are scattered in a larger area that is approximately 25 wide and 50 long. The calculatIon then states that the surrounding area around the 25 by 50 area has a uniform thickness of at least 0.800 Inches. However the calculation provides no reference or assumption that justifies this Input. The NDE datasheets of Bay 1 do not dearly substantiate this design input.
Item 10-Calculation Section 5 Sub Section Bay 13 documents that there ere 9 small areas In Bay 13 all less than 2 1/2 diameter, thinner than 0.736 but thicker than 0.536. These small areas are scattered In a larger area, which is approximately 25 wide and 50 long, The calculation then selects a 6 by 6 area within this region that is 0.677. This area is then compared to the Local Wall Acceptance Criteria, which is applicable for area up to 12 by 12, The smaller 6 by 6 area then Is judged to be the bounding area for the larger 25 by 50 area. This is then used as Justification that the larga 25 by 50 area is acceptable.
However, the alculation does not reconcile between the established crteria, for a 12 by 12 area, and the actual data, which has areas thinner than 0.736 scattered over a 25 by 50 area.
Item 11 -
Calculation Section 5 Sub Section Bay 13 documents that there are 9 small areas In Say 13 all less than 2 1/2 diameter, thinner than 0.736 but thicker than 0.536. These 9 small areas are scattered in a larger area that Is approximately 25 wide and 50 long. The calculation then states that the surrounding area has a uniform thickness of at least 0.600 Inches. However he calculation provides no reference or assumption that justifies this Input. The NDE datasheets of Bay 13 do not dearly substantlate this design Input.
Immediate actions taken:
Informed my Supervisor Recommended Actions.
listed below are recommendations for the calculation revision:
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AKt - Asigszmc1nt Xeport Page 4 of 5
- 1) The calculation should be revised to properly reference the NDE data sheets. Critical data sheets should be altached to the calculation,
- 2) The calculation should have a methodology section that documents how the data Is treated, Specifically, how the evaluation thickness Is developed and why it s acceptable to compare the evaluation thickness to the criteria of 0.736, It would be very helpful to site an Industry standard that prescribes and justifies this methodology.
- 3) The calculation uses a Local Wall Acceptance Criteria. The basis states that the criteria Is associated with a 9.5% reduction Is the ultimate theoretical buckling capacity of the drywell vessel shell, Revise calculation C-1302-187-5320-024 to state that a 9.5% reduction In buckling load still meets code allowables.
- 4) The calculation uses a Local Wall Acceptance Criteria. This criteria can be applied to small areas less than 12 by 12. Revise the calculation with additional criteria that defines the minimum acceptance distance between multiple local thin areas in which the Local Wall Acceptance Criteria can be applied.
5* The calculation uses a Very Local Wall Acceptance Criteria, This criteria can be applied to small areas less than 2 1/2 in diameter. Revise the calculation with additional criteria that defines the minimum acceptance distance between multiple local thin areas In which the Local Wall Acceptance Criteria can be applied.
- 6) The calculation uses a Very Local Wall Acceptance Crdtera, This criteria can be applied to smal! areas less than 2 1/2 In diameter, Revise the calculation to Justify that this criteria is applicable to the buckling loads.
- 7) The calculation documents that there are 8 small areas In Bay 1 and 9 small areas in bay 13, all less than 2 1/2 diameter, thinner than 0.736 but thicker than 0.536, In both bays the small areas are scattered in an area approximately 25 wide and 50 Iong. Revise the calculation to clearly demonstrate that these two areas meet design basis. The revision should clearly outine the methodology that Ii applied and the acceptance criteria.
What activities, processes, or procedures were Involved?
License Renewal Review of the Calculation What are the consequences?
Poor Design Basis Documentation Were any procedural requirements Impacted?
Yes - CC-AA-309-2001 Were there any adverse physical conditions?
None List of knowledgeable Individuals:
Howie Ray and Tom Qulntenz Operable Basis:
Reportable Basis:
SOC Reviewed by: RALPH C LARZO 03/06/2006 19:50:06 CST SOC Comments*
3/6/2006 RCL. ACIT assigned to revise calculation C-1302-187-5320-024.
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