ML20138C742
| ML20138C742 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 10/15/1985 |
| From: | Andrews R OMAHA PUBLIC POWER DISTRICT |
| To: | Butcher E Office of Nuclear Reactor Regulation |
| References | |
| LIC-85-438, TAC-58000, NUDOCS 8510230026 | |
| Download: ML20138C742 (7) | |
Text
Omaha Pubilc Power District 1623 Harney Omaha, Nebraska 68102 402/536-4000 October 15, 1985 i
LIC-85-438 Mr. Edward J. Butcher, Acting Chief Operating Reactors Branch #3 l
Division of Licensing Office of Nuclear Reactor Regulation U.S. iiuclear Regulatory Comission Washington, D.C.
20b55
Reference:
(1) Docket No. 50-285 (2) Letter OPPD (R. L. Andrews) to NRC (E. J. Butcher) dated June 17, 1985 (LIC-85-217).
Dear Mr. Butcher:
Exemption from ASME Boiler and Pressure Vessel Code Section XI The Omaha Public Power District, in reference (2), requested exemption f rom ISI testing of certain inaccessible sections of containment recirculaticn piping buried in concrete. Discussions with your staff have identified the need to submit additional information concerning this exemption request.
The changes from the reference (2) submittal are denoted by vertical lines in the right hand margin.
f l
Sincerely, 2: %
R. L. Andrews Division fianager Nuclear Production RLA/DJH/rs Attachment cc: LeBoeuf. Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
Washington, D.C.
20036 Nr. E. G. Tourigny, NRC Project Manager 1
Mr. P. H. Harrell, NRC Senior Resident Inspector 8510230026 851015 i
PDR ADOCK 05000285 0
PDR imotoymengangagagopponunny 4s w4
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BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of
)
OMAHA PUBLIC POWER DISTRICT Docket No. 50-285 i
(Fort Calhoun Station, Unit No. 1)
REQUEST FOR EXEMPTION l
Pursuant to Sections 50.12 and 50.55a(3) of the regulations of the U.S.
Nuclear Regulatory Comission ("the Comission"), 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 l
A technical discussion of the exemption request is set forth in Attach-ment A to this Request.
This discussion supplements that provided under a
Affidavit dated the 17 day of June,1985, relative to exception by hardship (10CFR50.55a). Additional information regarding compensatory measures 1
l has been provided.
i 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.
l 1
OMAHA PUBLIC POWER DISTRICT l
l R. L. Andrews Division Manager I.
Nuclear Production Subscribed and sworn before me I
the h day of Cerosr2
, 1985.
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sinnasoum-sim emen n.
J.T.0 LEA 90N f
MikD"@MN um
(/
Notary Public l
Attachment A Technical Report in Support of Exemption Request for Contalment Recirculation Lines
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Omaha Public Power District has recently became 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 contalment isolation valves HCV-383-3 and HCV-383-4 to openings in containment to achieve safety injection recirculation after a loss of coolant accident.
(These sections are l
labeled as 24-51-2001 and 2002 on the ISI isometrics). These sections are i
embedded in concrete, and thus inaccessible for examination of the welds in these sections.
i i
As can be seen from the attached copy of USAR Section 5.1.1, the peak contain-i ment pressure for design purposes is regarded as 60 psig and the peak contain-i ment temperature as 305'F.
This combination of temperature and pressure does
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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 sumer 1975 addenda to the ASME Section XI Code.
Under nomal operating conditions, however, (exclusive of a LOCA or main steam line break) the contalment recirculation line is ex-posed to no water, no temperature greater than containment ambient, and no i
j pressure greater than contaiment ambient.
The ability of the buried sections to perfom their safety function, when needed, is, therefore, never impaired by nomal operation. Thus, the only conditions we are concerned about are those of the post-accident situation, which have been analyzed. The conclu-
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sfons regarding that situation are summarized in USAR Section 6.2.1 as fol-i lows:
j i
r "A portion of the recirculation piping shown in Figure 6.2-3 is buried directly in concrete.
Under post-accident condi-t tions empressive thermal stressas will occur in the pipe.
l These themal stresses will not cause failure of the piping l
since the stainless steel is a ductile material and the i
stresses are compressive.
Reinforcing bars will absorb the i
tensile stress in the surroundf rg concrete "
The question of exempting open ended systems otherwise rated as Class 2 has 1
arisen at other operating plants, and has been addressed in the ASME D&PV Code Case N-408 (approved by the ASME, July 12, 1984) where the following question f
I is answered:
t I
Inqui ry:
When detennining the conponents subject to examination and estab-i lishing the examination requirements for Class 2 piping under 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?
l i
?
l The reply is given in four fettered sections, from which the following is
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l extracted' f.
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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-para-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-403 clearly addresses the problem, it has yet to be accepted by the NRC. Thus, the District believes that in the interim, an exemption for the buried sections of the containment recirculation 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 testing, and the associated individual penetration Type C test (our test number ST-CONT-3) which covers the buried sections in question, constitute alternate testing which, when combined with the analy-sis presented above will assure the functional integrity of the system.
Addi-tionally OPPD will examine as many of the welds in the buried sections of the line as are physically accessible from the I.D. during the 1985 refueling outage. OPPD will examine these welds using the VT-1 technique as described in the Section XI code (IWA-221, Visual Exam, VT-1). Also, if accessible, an examination will be made of the first weld outside of the buried sectians, which is located in the "subnarine hull" per ; rations in Room 23.
Such inspection activities were discussed with the NRC in a telephone conver',ation on Septenber 12, 1985.
The results of this work will be forwarded to the NRC after the 1985 "efueling outage for inclusion in the decision making process with regard to car exemption request.
d
SECTION 5 STRUCTURES 5.1 CONTAIh?fENT 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 bottem mat incorporating a depressed center portion for the This structure is lined with a steel membrane forming a continuous reactor.
steel cavelope 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 contain=ent free volume over a 24-hour period at the design pressure of 60 psig and design temper-ature of 305'F.
The containment structure steci envelope encompasses internal rein-forced concrete which is independent of the cylindrical vall above the founda-tion mat.
The internal concrete houses the reactor coolant system, and certain engineered safeguards components; it also provides localized biological chielding, 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 The containment structure is supported on steel piles driven to bed-rock located approximately 70 feet below grade.
l The concrete foundation mat is reinforced with high strength reinfore-ing steel and has a permanent access gallery extending under the containment 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 c'ach side of the vertical and following a helical pattern in two directions. The vall tendons terminate at the top of the wall and at the underside of the mat 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 g
prior to the stressing of the tendons, s.1-1
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