ML20028B899

Responds to Franklin Research Ctr 821029 Request for Info Re Plant Unique Analysis Rept Concerning Mark I Containment Program.All Small & Large Bore Piping Associated W/Containment Sys Considered in Evaluations

ML20028B899
Person / Time
Site:	Cooper
Issue date:	12/01/1982
From:	Pilant J NEBRASKA PUBLIC POWER DISTRICT
To:	Vassallo D Office of Nuclear Reactor Regulation
References
TAC-07934, TAC-7934, NUDOCS 8212070175
Download: ML20028B899 (5)

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GENERAL OFFICE S

Nebraska Public Power District " " "iEss"Eise" tea ^'** '"

December 1,1982 Mr. Dominic B. Vassallo, Chief Operating Reactors Branch #2 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Mark I Containment Program -

Plant Unique Analysis Report (PUAR)

Reference:

Franklin Research Center Request for Information TER-C5506-316 transmitted to NPPD on October 29, 1982 The following is provided in response to the questions asked by Franklin Research in their request for information. For clarity the questions are first restated and the response is then provided.

Question 1: Indieste if the piping systems such as vent drains have been corr.,1dered in the plant unique analysis.

Response: Yes, all small bore and large bore piping associated with the CNS containment system have been considered in the evaluations. The procedures and results are described in Section 6 of the PUAR. The vent drain line was evaluated as a component of the vent system. Its evaluation is described in Subsection 4.4 of the PUAR.

Question 2: With reference to Section 1.2.1.2 of the PUA report, clarify which existing structural components were designed, fabricated, and installed to AISC Code or codes other than ASME Boiler and Pressure Vessel Code.

Response: Modifications to all existing structural components except drywell steel framing were designed, fabricated, and installed to the requirements of the ASME Boiler and Pressure Vessel Code,Section III. The modifications to the drywell steel l framing were based on criteria of the ASME Code, Subsection NF with Service Level C and D allowables modified to limit stresses to approximately 0.9 of yield. The Code evaluation procedure for the drywell steel is described in Subsection 5.2.4.5 of the PUAR.

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Mr. Dominic Vassallo Page 2 December 1,1982 l Question 3: With regard to the pumps and valves attached to essential piping systems and not qualified, using Service Limits A or B, indicate whether the operability criteria are satisfied.

Response: Valves Requirements for valve operability were satisfied by qualifying all valves using Service Level B stress allowables for all postulated event combinations.

Pumps Pump operability is considered to be the ability of the pump to provide adequate fluid delivery during and after a LOCA.

During such an event, the pump shaft displacement should not constrain movement of the impeller to the extent that fluid flow is impeded. The loading on the pump due to the Mark I hydrodynamic loads is transmitted to the pump only through the suction and discharge nozzles. Because of the relative stiffness of the pump nozzle to the pump casings significant levels of nozzle deformation would have to exist before any significant loading would be seen by the pump shaft and the impeller. Thus if the nozzles do not exhibit large deformations, no significant deformations will occur at the shaft due to hydrodynamic loads. Significant displacements of the shaft can then only be induced by seismic loading.

Because the design seismic loading has not changed, no inertia effects were considered for pump operability.

Suction and discharge nozzles of the pumps were evaluated for Mark I loads and the stresses were shown to be within yield limits , llence, they do not exhibit significant deformation and pump operability criteria are satisfied.

Question 4: Indicate whether the containment vacuum breaker valves mounted on the vent internal to the torus or on piping associated with the torus have been analyzed as Class 2 components as required by the criteria.

Response: There was an understanding between the Mark I Owner's Group and the NRC not to evaluate the containment vacuum breaker valves mounted on the vent header as a part of the Mark I Program. The valves will be addressed in a plant unique evaluation to be submitted by NPPD to the NRC by April, 1983. The vent header penetration at the location of these valves was evaluated in the PUAR. The modifications are described in Subsection 1.3.2.2.6 of the PUAR.

Question 5: Indicate whether all the applicable loads have been considered in the analysis and provide justification for neglecting the loads indicated in the attached Table 1.

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Mr. Dominie Vassallo Page 3 December 1,1982 Response: Yes, all applicable load cases have been considered in the analyses. The loads specifically indicated in Table 1 of the NRC letter are addressed below:

Pool Swell Impact and Drag Loads on the Main Vent -

These loads were considered and are discussed in Subsection 2.4.3.3.1 of the PUAR.

Froth Impingement on the Torus Shell and Support System -

Torus shell structural evaluations were performed using local torus shell pressure time histories which were obtained from plant-unique QSTF tests. As a result , these loads are included in the pool swell loads on the shell and support system (see Subsection 2.4.3.2 of the PUAR).

Froth Impingement on the S/RV Piping - S/RV piping does not experience any froth impingement loads since the airspace portion of the piping is not located in regions subjected to these loads. Ilowever, these loads were considered for the S/RVDL B support in airspace which is located in froth impingement affected region.

Pool Fallback Loads on the S/RV Piping - The airspace portion of the wetwell S/RVDL A is oriented vertically and is therefore not subjected to pool fallback loads. The routing of S/RVDL B includes horizontal piping which is exposed to pool fallback loads. These fallback loads were considered and were found to be bounded by the impact and drag loads on the i S/RVDL B (see Subsection 5.3.3.2.2 of the PUAR).

! Pool Fallback Loads on Wetwell Interior Structures in Airspace

- These loads were considered for interior structures located l in the torus airspace. These structures are listed in Table 2.5 of the PUAR.

Condensation Oscillation and Chugging Submerged Structure Loads on S/RV Piping - These loads were considered for the wetwell portions of the S/RVD piping. The procedures are discussed in Subsection 5.3.3.2.3 of the PUAR.

Condensation Oscillation and Chugging Lateral Loads on Downcomers to Evaluate Vent Hender and Downcomer Stresses -

These loads were considered and the procedures are discussed in Subsections 4.2.3.2.4 and 4.2.3.2.5 of the PUAR.

T-Quencher Jet Loads on Downcomers - The downcomers are not intercepted by the jet.

S/RVDL Environmental Temperature Loads for S/RV Piping -

The S/RVDLs were analyzed for the effects of thermal expansion using the design temperatures for the drywell and wetwell portions of the piping. These procedures are described in Subsectione 5.2.3.2.3 and 5.3.3.2.6 of the PUAR.

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Mr. Dominic Vassallo Paga 4 December 1,1982 Question 6: Indicate whether all the bolted connections in linear type component supports meet the requirements of the criteria as specified in Section 4.4b of Reference 1.

Response: Yes, all bolted connections in linear type component supports meet the requirements of the criteria specified in the Plant Unique Analyr% Application Guide (NEDO-24583-1).

Question 7: If the methodology presented in Reference 4 is finally accepted by the NRC, the Licensee is required to confirm that the fatigue usage factors for the SRV and the torus attached piping are sufficiently small, therefore, a plant unique fatigue analysis of these piping systems is not warranted.

Response: Yes, confirmation that the fatigue usage factors for CNS Class 2 piping are small will be addressed in a letter from NPPD if the methodology presented in Reference 4 is accepted by the NRC.

Question 8: Justify the reasons for not considering a 1800 segment of the torus (as required by the criteria) in order to determine the effects of seismic and other nonsymmetric loads.

Response: Symmetry properties were utilized to determine 180 torus response due to seismic and other nonsymmetric loads. A 90?

segment of the torus is sufficient to accurately predict torus shell response and seismic-tic loads resulting from a horizontal seismic event because the torus as well as the seismic tie locations are symmetric about perpendicular axes.

Non-symmetric S/RV discharge loads were considered in a global sense when evaluating the reactions at the seismic ties (see Subsection 3.3.3.2 of the PUAR).

Question 9: Indicate the piping systems that were classified as essential piping systems and specify the appropriate loading

combinations.

Response: Although all piping may not be essential, all S/RVD and Torus Attached piping systems were classified as essential for all load combinations. The load combinatians used in the piping evaluations are listed in Tables 5.2, 5.7, 6.1, and 6.7.

Question 10: With regard to the torus attached piping, indicate whether the anchor displacements due to torus motion were considered, as defined in Section 6.7 of the criteria.

i Response: Yes, effects of anchor displacements due to torus motion were considered as defined in Section 6.7 of the Plant Unique Analysis Application Guide (NEDO-24583-1) . A detailed description of the procedures used is contained in

! Subsections 6.2.3 and 6.3.3 of the PUAR.

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.. .* Mr. Dominic Vas=llo Pago 5 December 1,1982 Question 11: Indicate if Tables 3.8, 4.6, 4.12, 5.4, 5.5, 5.6, 5.8, 6.4, and 6.6 of the PUA report correspond to the maximum stress encountered for the different structural components reviewed.

Response: Yes, Tables 3.8, 4.6, 4.12, 5.4, 5.5, 5.6, 5.8, 6.4, and 6.6 of the PUAR indicate the maximum stresses encountered for the components reviewed.

If you have any further questions about this, please contact me.

Sincerely, k b Ja . Pilant Division Manager of Licensing & Quality Assurance JMP/tch:snl/l Attachment t

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