ML17298B044
| ML17298B044 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/07/1984 |
| From: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Knighton G Office of Nuclear Reactor Regulation |
| References | |
| ANPP-29684-EEVB, GL-84-04, GL-84-4, NUDOCS 8406130169 | |
| Download: ML17298B044 (10) | |
Text
REGUI ATOR NFORMATION DISTRIBUTION S EM (R IDS)
ACCESSION NBR'8406130169 DOC,DATE: 84/06/07 NOTARIZED:
NO DOCKET FACIL:STN-50-528 Palo Verde Nuc]ear Station~
Uni,t 1i Ar)zona Publi 05000528 STN-50-529 Palo Verde Nuclear Station~
Unit 2i Arizona Publi 050005?9 STN-50 530 Palo Verde Nuclear Station~
Unit 3~ Arizona Publi 05000530 AUTH ~ NAME AUT(OR AFFILIATION VAN BRUNTiE.E.
Arizona Public Service Co.
RECIP ~ NAME RECIPIENT AFFILIATION KNIGHTONiG ~
Licensing Branch 3
SUBJECT:
Requests partial exemption from GDC 4 to apply advanced fracture mechanics techniques to postulated pipe breaks in CESSAR design rcs main loop piping, Response requested by Oct 1984>
DISTRIBUTION CODE!
B001S COPIES RECEIVED LTR, ENCL SIZE ~
TITLE: Licensing Submittal:
PSAR/FSAR Amdts.
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- plant,
'05000528 05000529 05000530 RECIPIENT ID CODE/NAME NRR/DL/ADL NRR LB3 LA INTERNAL: ELD/HDS3 IE/DEPER/EPB 36 IE/DQASIP/QAB21 HRR/DE/CEB 11 NRR/DE/EQB 13 NRR/DE/MEB 18 NRR/DE/SAB 24 NRR/DHFS/HFEB40 NRR/DHFS/PSRB NRR/DSI/AEB 26 NRR/DSI/CPB 10 NRR/DS I/ICSB 16 NRR/DSI/PSB 19 NRR/DSI/RSB 23 RGN5 EXTERNAL: ACRS 41 DMB/DSS (AMDTS)
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Arizona Public Service Company Director of Nuclear Reactor Regulation Attention:
Mr. George Knighton, Chief Licensing Branch No.
3 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
20555 June 7,
1984 ANPP-29684-EEVB/VFQ
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Units 1, 2 and 3 Docket Nos.
STN-50-528/529/530 Request for Partial Exemption to GDC4 File:
84-056-026. G.l.01.10
References:
(A)
Generic Letter 84-04, D.G.
Eisenhut to PWR Licensees, Construction Permit Holders and Applicants for Con-struction Permits, dated February 1, 1984 (B)
Letter LD-83-053, A.E.
Scherer to D.G. Eisenhut, Basis for Design of Plant Without Pipe Whip Restraints, dated June 14, 1983 (C)
Letter LD-83-108, A.E.
Scherer to D.G. Eisenhut, Basis for Design of Plant Without Pipe Whip Restraints, dated December 23, 1983 (D)
- Letter, J.J.
Ray to W.J.
- Dircks, Fracture Mechanics Approach to Pipe Failure, dated June 14, 1983
Dear Mr. Knighton:
Combustion Engineering (CE),
and the NRC staff have discussed on several occasions the application of advanced fracture mechanics techniques to certain postulated pipe breaks in the CESSAR design Reactor Coolant System (RCS) main loop piping.
- APS, based on these discussions and information provided, proposes to utilize those techniques to eliminate mechanical and structural load effects associated with postulated RCS main loop pipe breaks.
In Reference (A),
the NRC indicated that advanced fracture mechanics could be employed as a basis for an alternate approach to these postulated pipe breaks.
To facilitate application of those techniques, APS hereby submits this request for partial exemption from General Design Criterion 4 (GDC-4).
As zequired by Reference (A) and as provided by 10CFR50.12(a),
Arizona Public Service Company
- requests, for Palo Verde Nuclear Generating Station Units 1, 2,
and 3,
a partial exemption from the provisions of GDC-4.
Specifically, APS requests exemption from those portions which require protection of structures,
- systems, and components against certain dynamic (including mechanical and structural loading) effects associated with postulated RCS main loop pipe breaks.
This exemption pertains to all postulated breaks specified in Section 3.6 of CESSAR-F.
APS does not seek exemption from GDC<<4 for other postulated breaks.
This request has
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Director of Nuclear Reactor Regulation Request for Partial Exemption to GDC4 Page 2
no effect on the PVNGS design basis for environmental, containment, or ECCS analyses.
As justification for this exemption, the following information is provid-ede 1.
In Reference (B) which was later revised in Reference (C),
CE submit-ted for NRC staff review a fracture mechanics analysis to validate the "leak-before-break" failure scenario for the System 80 design.
This submittal also provided details of the support system design to demonstrate that there is sufficient design margin for seismic exci-tation as recommended by the ACRS in Reference (D).
Although staff review of this submittal is not complete, no significant deficiencies have been identified to date.
CE believes that the approach in Ref-erence (C) is more conservative than other submittals already approved by the staff.
2.
Reference (C) demonstrates that for the System 80 RCS main loop piping:
a)
A substantial sized flaw in the piping would not grow through the wall nor extend significantly in length during the plant design lifetime.
b) If a flaw were to grow through the wall of the piping, it would open sufficiently to leak many times the maximum allowable leak-age before extending anywhere near critical crack length.
c)
A very long through wall crack (many times longer than a leak detectable longitudinal or circumferential crack length) would remain stable under normal operation plus SSE loadings.
This demonstration provides sufficient justification for elimination of large postulated breaks from the design basis for the PVNGS Units 1, 2, and 3 RCS main loop piping.
3.
The ACRS in Reference (D) has approved the application of the afore-mentioned fracture mechanics techniques to the analysis of asymetric blowdown loads.
Reference (D) states "That is, there is no known mechanism in PMR primary piping material for developing a large break without going through an extended period during which the crack would leak copiously."
4.
The NRC staff has reviewed the PVNGS leakage detection systems and found them to meet the requirements of GDC-30 and the guidelines of Regulatory Guide 1.45.
This is stated in the PVNGS SER (NUREG-0857)
Section 5.2.5.
PVNGS Technical Specifications Section 3/4.4.5 will require at least one of the required leakage detection systems be operable to continue plant operation.
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Director of Nuclear Reactor Regulation Request for Partial Exemption to GDC4 Page 3
5.
This exemption would result in radiation exposure reduction to plant maintenance personnel.
Assuming each restraint is removed once for Inservice Inspection (ISI), a total of 560 man-rem per unit would be eliminated.
Total man-rem savings for PVNGS Units 1, 2, and 3 would be 1680 man-rem.
Thus the exemption, if granted, would be of signif-icant benefit in the AIBA concept of plant operation.
6.
An installation cost savings would be realized for PVNGS Units 2 and 3.
This exemption would result in a
savings of 4150,000.00 for tightening and adjustment of pipe whip restraints in Unit 2.
Pipe whip restraint elimination for Unit 3
would result in savings of 5450,000.00 for fabrication and installation.
The restraints and stops for Unit 1 are currently installed and adjusted.
Cost savings would also be realized in that the maintenance associat-ed with ISI would be reduced.
Assuming each restraint or stop is removed only once would result in a savings of 4280,000.00
-per unit.
The total maintenance cost savings would be 5840,000.00 for PVNGS Units 1, 2,
and 3.
The restraints currently installed in Unit 1
could be removed at minimal cost.
Total Cost Savings:
Unit 1 Unit 2 Unit 3 Total 280,000.00 430,000.00 730 000.00 1,440,000.00 ISI ISI and Adjust ISI, Install, and Adjust 7.
There would be no adverse effect on safety resulting from this exemp-tion.
This request, if granted, would have no effect on the poten-tial for occurrence or the severity of accidents previously consid-ered by the staff.
Thus, while presenting no increased risk to the health and safety of the general public a
known savings of 1680 man-rem to maintenance personnel can be achieved.
APS requests that review of this exemption request be completed prior to October of 1984 to avoid unnecessary adjustment of the pipe whip restraints in PVNGS Unit 2 and to eliminate the need for further fabrica-tion and installation of restraints in PVNGS Unit 3.
As always, APS is prepared to meet with the staff at their convenience to resolve any ques-tions and to provide additional information that may be necessary to facilitate a prompt review.
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Director of Nuclear Reactor Regulation Request for Partial Exemption to GDC4 Page 4
If you have any questions, please contact me.
Very truly yours E. E. Van Brunt, Jr.
APS Vice President Nuclear Production ANPP Project Director EEVB/TFQ/js cc:
E.A. Licitra A.C. Gehr
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