ML20127A771
| ML20127A771 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/17/1985 |
| From: | Andrews R OMAHA PUBLIC POWER DISTRICT |
| To: | Butcher E Office of Nuclear Reactor Regulation |
| References | |
| LIC-85-217, TAC-58000, NUDOCS 8506210251 | |
| Download: ML20127A771 (8) | |
Text
.
Omaha Public Power District 1623 Harney Omaha. Nebraska 68102 402/536 4000 June 17,1985 L IC-85-217 Mr. Edward J. Butcher, Acting Chief Operating Reactors Branch #3 Division of Licensing Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555
Reference:
Docket No. 50-285
Dear Mr. Butcher:
Exemption from ASME Boiler and Pressure Vessel Code Section XI It has came to the attention of Omaha Public Power District that certain sec-tions of containment recirculation piping buried in concrete are within the scope of ASME Boiler and Pressure Yessel Code Section XI testing requirenents.
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Because the required testing is not practical, a request for the exemption of this piping from the testing requirenents is being made. The application fee l
of $150.00 is also attached.
Sincerely,
?:e R. L. Andrews Division Manager Nuclear Production RLA/DJM/rh Attachment cc:
LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
Washington, DC 20036 Mr. E. G. Tourigny, NRC Project Manager Mr. L. A. Yandell, NRC Senior Resident Inspector P
B506210251 850617 PDR ADOCK 05000285 I(
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BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of
)
OMAHA PUBLIC POWER DISTRICT
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Docket No. 50-285 (Fort Calhoun Station,
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Unit No.1)
)
REQUEST FOR EXEMPTION Pursuant to Sections 50.12 and 50.55a(3) of the regulations of the U.S.
Nuclear Regulatory Commission ("the Commission"), Omaha Public Power District,
("the District") holder of Facility Operating License No. DPR-40, herewith requests relief from the specific requirements of the ASME Boiler and Pressure Vessel Code,Section XI, for certain containment recirculation piping buried in concrete.
A technical discussion of the exemption request is set forth in Attach-ment A to this Request. This discussion demonstrates that " compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety." (10 CFR 50.55a(3)) Additionally, a check for the application fee, $150.00, accompan-ies this request.
WHEREFORE, the District respectfully requests that it be exempted from the requirements imposed by certain portions of the ASME Boiler and Pressure Vessel Code,Section XI as detailed and delineated in Attachment A.
OMAHA P TRICT R. L. Andrews Division Manager Nuclear Production Subscribed and sworn before me
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, 1985.
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i Attachment A Technical Report in Support of Exemption Request for Containment Recirculation Lines Omaha Public Power District has recently become aware that a portion of two piping systems at the Fort Calhoun facility cannot be examined per the require-ments of the Section XI Code. These sections run from containment isolation valves HCV-383-3 and HCV-383-4 to openings in containment to achieve safety injection recirculation af ter a loss of coolant accident.
(These sections are labeled as 24-SI-2001 and 2002 on the ISI isometrics). These sections are embedded in concrete, and thus inaccessible for examination of the welds in these sections.
As can be seen from the attached copy of USAR Section 5.1.1, the peak contain-ment pressure for design purposes is regarded as 60 psig and the peak contain-ment temperature as 305'F. This combination of temperature and pressure does not allow the buried sections of 24-SI-2001 and 24-SI-2002 (see attached ISI isometrics) to be exempted under IWC-1220(A) of the summer 1975 addenda to the ASME Section XI Code. Under normal operating conditions, however, (exclusive of a LOCA or main stean line break) the containment recirculation line is ex-posed to no water, no temperature greater than containment ambient, and no 4
pressure greater than contaimeent ambient. The ability of the buried sections to perform their safety function, when needed, is, therefore, never impaired by normal operation. Thus, the only conditions we are concerned about are those of the post-accident situation, which have been analyzed. The conclu-sions regarding that situation are senmarized in USAR Section 6.2.1 as fol-l lows:
i "A portion of the recirculation piping shown in Figure 6.2-3 is buried directly in concrete. Under post-accident condi-i tions compressive thermal stresses will occur in the pipe.
These thermal stresses will not cause failure of the piping since the stainless steel is a ductile material and the stresses are compressive. Reinforcing bars will absorb the tensile stress in the surrounding concrete."
The question of exempting open ended systems otherwise rated as Class 2 has arisen at other operating plants, and has been addressed in the ASME B&PV Code Case N-408 (approved by the ASME, July 12,1984) where the following question is answered:
4 Inqui ry:
When determining the canponents subject to examination and estab-lishing the examination requirements for Class 2 piping under i
Section XI, what alternative exemptions to those stated in IWC-1220 and what alternative examination requirements to those stated in IWC-2500, Category C-F may be used?
1 The reply is given in four lettered sections, from which the following is extracted:
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Section ( A):
The following components (or parts of components) of RHR, ECC and CHR systems (or portions of systems) are exempt from vol-umetric and surface exam requirements of IWC-2500: Sub-pa ra-graph (6) piping and other components of any size beyond the last shut off valve in open ended portions of systems that do not contain water during normal plant operating conditions.
Thus, when the NRC accepts this code case, an exemption will exist for the sections of the containment recirculation lines from HCV-383-3 and HCV-383-4 to the open ended portion of those lines in the containment.
Although Code Case N-408 clearly addresses the problem, it has yet to be ac-cepted by the NRC. Thus, the District believes that in the interim, an ex-emption for the buried sections of the containment re-circulation lines is necessary. The District further points out that the same situation existed under the 1975 addenda of the ASME Section XI Code through the first 10 year inspection interval as well. We do not, however, believe that this situation has any safety significance for the same reasons we have stated to justify an exemption from this testing requirement for the current 10 year interval.
Omaha Public Power District believes that the standard Appendix J (of 10 CFR
- 50) integrated leak rate testig, and the associated individual penetration test (our test number ST-CONT-3) which covers the buried sections in question, constitute alternate testing which when combined with the analysis presented above will assure the functional integrity of the system.
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SECTION 5 h)
STRUCTURES 5.1 CONTAINMENT STRUCTURE 5.1.1 General Description The containment structure (see Figures 5.1-1 and 5.1-2) is a rein-forced concrete pressure vessel partially prestressed, with cylindrical walls, domed roof and a bottom mat incorporating a depressed center portion for the reactor. This structure is lined with a steel membrane forming a continuous steel envelope located at the inner surface of cylinder, roof and mat to provide a vapor-tight container. The structure is designed to safely withstand all internal and external loadings which can be expected to occur during the life of the plant. The design maximum leak rate is 0.2 percent of the containment free volume over a 24-hour period at the design pressure of 60 psig and design temper-ature of 305*F.
The containment structure steel envelope encompasses internal rein-forced concrete which is independent of the cylindrical wall above the founda-tion mat.
The internal concrete houses the reactor coolant system, and certain engineered safeguards components; it also provides localized biological shielding, and the required missile protection for the liner, engineered safeguards equipment, piping, and instrumentation and controls. The refueling cavity is also part of the internal concrete structure.
5.1.2 Structural Features s
The containment structure is supported on steel piles driven to bed-rock located approximately 70 feet below grade.
The concrete foundation mat is reinforced with high strength reinforc-ing steel and has a permanent access gallery extending under the containment I
structure directly below the cylindrical wall.
The cylindrical concrete wall is conventionally reinforced and is~,
prestressed by a system of. post-tensioned tendons inclined at 45 degrees to e'ach side of the vertical and following a helical pattern in two directions. The call tendons terminate at the top of the wall and at the underside of the mat i
within the access gallery.
The domed roof is conventionally reinforced and is prestressed by a three way post-tensioned tendon system; in plan, the three groups of tendons are mutually inclined at 120 degrees.
Tendons are placed in steel conduits which are filled with a waterproof grease to prevent corrosion. The anchors of all tendons are located so that they are accessible for inspection, testing and retensioning at all times during the life of the plant.
A temporary opening was provided in the cylindrical wall for the entry of major equipment components into the containment. This opening was closed
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prior to the stressing of the tendons.
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