ML20128Q857
| ML20128Q857 | |
| Person / Time | |
|---|---|
| Issue date: | 03/13/1981 |
| From: | Woodruff R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML20126K036 | List: |
| References | |
| FOIA-85-301 NUDOCS 8507270065 | |
| Download: ML20128Q857 (3) | |
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a ue i '( ' $ - o g G cck UNITED STATES
[ g NUCLEAR REGULATORY COMMISSION 5 j WASHINGTON, D. C. 20556 k-p# .
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MAR 131981 MEMORAN M FOR:
E. L. Jordan, Acting Chief, Reactor Engineering Branch, IE '
FROM: ,
R. W. Woodruff Acting Chief. Meachnical, Structural and ;
t Metallurgical Branch, REB, IE '
SUBJECT:
EVALUATION OF A PROPOSAL BY CIE t
i- Proposal
, In an unsolicited proposal from Computerized Interference Elimination. Inc.
(CIE),
described. their capability to identify interferences in piping systems was
- CIE reviews design drawings and inputs into computer memory a mathematical description of the boundaries of the space being examined and the configurations of the systems and structures contained in the space.
The computer then identifies any portions of systems or structures that i
occupy the same volume as indicated by the drawings. 1
! i
- CIE's proposal states that the interference analysis would be applied on a ~
- demonstration basis to 50,000 to 75,000 cubic feet of space in the containment or auxiliary building of any single nuclear unit designated by IE. CIE would require that IE furnish reproducible drawings which clearly depict system
- sizes and locations and the necessary dimensions in three coordinates. Where dimensions are not included on the drawings, CIE would obtain the information by scaling to the best of their ability.
would provide a dimensioned sketch of each interference found.After performing the i In their proposal, CIE states that they are not a qualified engineering firm and that they assume no responsibility for engineering decisions or evaluations.
Background
i l Because of the complexity of nuclear power plants, piping interferences in safety-related take precautions systems to avoiddosuch result from the design process even though designers interferences.
i Interferences become obvious during modified. construction and piping is rerouted or offending components are Where piping is rerouted, design drawings are revised to show the
- as-built configuration and an engineering evaluation is performed to assure that rerouted piping has adequate strength. t 1
As a result of inspections by IE.and by some licensees, several piping non-i conformances were discovered in late 1978 and early 1979 which potentially l t
affected the validity of seismic analyses for some operating nuclear units.
IE subsequently issued Bulletin 79-14 in July,19.79. This bulletin required i he i -g$$l?$a- _ _ _ __
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- E. L. Jordan MAR 131981 1 1
licensees to verify the as-built configuration of their safety-related piping i systems and to compare the verified piping configuration to the configuration i assumed in the seismic analyses for these systems. Where significant differences were found, licensees were required to redo those analyses and to modify the systems, if necessary, to meet design criteria. This effort is essentially complete for operating plants.
1 '
In discussions with IE, CIE has advanced the notion that application of an interference analysis to a selected space at an operating reactor would be helpful in detenntning the adequacy of the licensee's response to Bulletin "
79-14.
Evaluation There are three methods for identifying interferences in pipi_ng systems during the design process. These are:
i
- 1. physical modeling,
! 2. mathematical modeling, i.e., the method used by CIE, and
- 3. cross checkt.ng of drawings.
' Mathematical modeling, using a qualified computer program, can be as effective fordrawings.
of this purpose as physical modeling and more effective than cross checking For an operating unit that has accurate as-built drawings, application of methods (1), (2) and (3) cannot possibly identify real interferences if these drawings are used for the analysis. Use of original design drawings for this i
purpose would not have merit since neither the as-built system nor the seismic analysis would confonn in all respects to those drawings.'
Because Bulletin 79-14 required detailed inspection of safety-related systems and revision of drawings to reflect the as-built configuration, because of i reports of deficiencies submitted by licensees, and because of IE's inspection of this effort, it is apparent that the accuracy of as-built drawings for safety-related systems has been significantly improved.
CIE's proposal covers 50.000 to 75,000 cubic feet of space at a single operating j unit. Assuming 1 to 2 million cubic feet for the space occupied by safety-related systems at a single unit and 70 operating units, the sample size is less than 0.11. The likelihood of fin'di_ng an as-built drawing deficiency after compliance with Bulletin 79-14 is small and would pose an undue burden for the licensee selected for this demonstration.
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E. L. Jordan - 3-MAR 131981 Conclusion Mathematical modeling 'can be effective in identifying piping interferences duringidesign but does not have merit when applied to drawings that have been reyised during a careful inspection of installed systems.
Reconnendation ,
CIE!s proposar should be rejected.
- b. ,
R. W. Woodruff Acti_ng Chief Mechanical. Structural and Metallurgical Branch DRRRI. IE cc: J. H. Sniezek, IE
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