ML16340C684
| ML16340C684 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/01/1982 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Cooper W TELEDYNE ENGINEERING SERVICES |
| Shared Package | |
| ML16340C683 | List: |
| References | |
| NUDOCS 8207140398 | |
| Download: ML16340C684 (8) | |
Text
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Dr. William Cooper Teledyne Engineering Services 130 Second Avenue Haltham, Massachusetts 02264
Dear Dr. Cooper:
During our meeting of June 10, 1982 I noted that Brookhaven National Laboratory (BNL), a staff consultant, was preparing a report of studies performed to aid in our review of the seismic design of the Diablo Canyon Nuclear Power Plant.
I also indicated that I would provide that report to Teledyne Engineering Services for its use in the Diablo Canyon Nuclear Power Plant Unit 1 Independent Design Verification Program
( IDVP).
A pre-print copy of the final report entitled "Independent Seismic Evaluation of the Diablo Canyon Unit 1 Containment Annulus Structure and Selected Piping Systems" is enclosed.
All supporting technical documentation such as computer input and output is available for further information.
The Brookhaven study is a detailed analysis of certain aspects of the seismic response of the containment annulus steel structure and a sample of attached piping at Diablo Canyon Unit No. 1.
In addition to indepen-dent modelling of the annulus steel structure and piping, Brookhaven also independently developed vertical floor response spectra at all elevations of the annulus structure and performed an independent analysis of two piping systems supported by the annulus structure.
All computer codes employed were verified and results were checked with othe codes available in the public domain.
Since early results indicated significant differences between the Brookhaven calculations and the original work by URS/Blume and PGGE, Brookhaven was also requested by the staff to attempt duplication of the original analyses using the models and computer inputs developed by URS/Blume and PG5E.
Our initial review of the report has lead us to conclude that, as a
minimum, the following items require further exploration and assessment as to their generic implications.
1.
The distributed masses of the steel members comprising the annulus structure. were not included in the mathematical model used in the original seismic analysis.
2.
The mathematical model used in the original analysis considered the joints between the beams and columns to be rigid whereas the Brook-haven interpretation of the drawings indicate these joints are more appropriately considered flexible (shear carrying only).
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Statements on page ll of the URS/Blume May 1979 report "Diablo Canyon Nuclear Plant Unit 1 Containment Structure, Dynamic Seismic Analysis for 7.5 N Hosgri Earthquake",
Hay 1979, concerning the structural connections are not consistent with the mathematical model used in the original analysis.
4.
The response spectrum smoothing techniques employed in the original analyses appears inconsistent with good practice and the FSAR comoitments.
5.
Design dimensions were used instead of the as-built dimensions in the two piping problems sampled (PG&E piping models, 6-11 and 4A-26).
6.
The 5D bends in the piping analysis were modelled as long radius bends.
This has the effect of softening the model and reducing the natural frequencies.
7.
The piping support forces computed by the BNL model are much larger than those computed by the PG&E model.
As I stated at our meeting in Haltham, I recommend that you treat the Brookhaven report as an input in your decision making process regarding the seismic design adequacy of the Diablo Canyon Unit l.
You should inform us shortly (e.g. next semi-monthly report) on how you will consider the report in the IDVP and how appropriate actions will be taken in the program.
Should you require any clarification on the
- report, we request that you contact the NRC Project IIanager to make the necessary arrangements.
/~f Harold R. Denton, Director Office of Nuclear Reactor Regulation DISTRIBUTION:
H. Denton R. Vollmer R. Engelken J.
Crews D. Eisenhut R. Tedesco J. Knight F. Hiraglia H. Schierling B. Buckley P.
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Dr. William Cooper Teledyne Engineering Services 130 Second Avenue Illaltham, Massachusetts 02254
Dear Dr. Cooper:
Duping our meeting of June 10, 1982 I note that Brookhaven National Laboratory (BNL), a staff consultant, was preparing a report of studies performed to aid in our review of the s
smic design of the Diablo Canyon Nuclear Power Plant.
I also in icated that I would provide that report to Teledyne Engineering Servi 4s for its use in the Diablo Canyon Nuclear Power Plant Unit 1 Independ nt Design Verification Program
( IDVP).
A pre-print copy of the f nal report entitled "Independent Seismic Evaluation of the Diablo anyon Unit 1 Containment Annulus Structure and Selected Piping S
tems" is enclosed.
All supporting technical documentation such a
computer input and output is available for further information.
The Brookhaven study is a d ailed analysis of certain aspects of the seismic response of the co ainment annulus steel structure and a sample of attached piping at Dia o Canyon Unit No. 1.
In addition to indepen-dent modelling of the any lus steel structure and piping, Brookhaven also independently devegbped vertical floor response spectra at all elevations of the annu Os structure and performed an independent analysis of two pipin systems supported by the annulus structure.
All computer codes employ d were verified and results were checked with other codes availabl in the public domain.
Since early results indicated signific t differences between the Brookhaven calculations and the original w rk by URS/Blume and PG&E, Brookhaven was also requested by the taff to attempt duplication of the original analyses using the model and computer inputs developed by URS/Blume and PG&E.
Our initial r iew of the report has lead us to conclude that, as a
minimum, the ollowing items require further exploration and assessment as to their eneric implications.
1.
The d tributed masses of the steel members comprising the annulus stru ure apparently were not included in the mathematical model use in the original seismic analysis.
2.
TP mathematical model used in the original analysis apparently bnsidered the joints between the beams and columns to be rigid ihereas the Brookhaven interpretation of the drawings indicate these Joints are more appropriately considered flexible (shear carrying only).
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3.
Statements on page 11 of the URS/Blume Hay 1979 report "Diablo Canyon Nuclear Plant Unit 1 Containment Structure, Dynamic Seismic Analysis for 7.5 N Hosgri Earthquake",
Nay 1979, concerning the structural connections may not be consistent with the mathematical model used in the original analysis.
4.
The response spectrum smoothing techniques employed in the original analyses appears inconsistent with the FSAR cottmitments.
5.
Design dimensions were apparently used instead of the as-built dimensions in the two piping problems sampled (PGSE piping models, 6-11 and 4A-26).
6.
The 5D bends in the piping analysis were apparently modelled as long radius bends.
This has the effect of softening the model and reducing the natural frequencies.
7.
The piping support forces computed by the BNL model are much larger than those computed by the PGIIE model.
As I stated at our meeting in Haltham, I recommend that you consider the Brookhaven report in your decision making process for Phase I of the IDVP regarding the seismic design adequacy of the Diablo Canyon Unit 1.
You should inform us of your views regarding the +Roof the BIIL results and of their generic implications.
Should you require any clarification on the report, we request that you contact the NRC Project Manager to make the necessary arrangements.
Harold R. Denton, Director Office of Nuclear Reactor Regulation DISTR IBUTION:
H. Denton R. Vollmer R. Engelken J.
Crews D. Eisenhut R. Tedesco J. Knight F. Miraglia H. Schierling B. Buckley P.
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