ML20198G158
| ML20198G158 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 03/05/1976 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Deyoung R Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-1110 NUDOCS 8605290261 | |
| Download: ML20198G158 (3) | |
Text
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Richard.C. DeYoung, Assistant Director for Light Water Reactors, Pl4 REQUEST.FOR ADDITIONAL INFORMATION FOR THE WPPSS 1 AND 4 REACTOR CAVITY PRESSURERESPONSE(TAR 3217)
The Containment Systems Branch (CSB) has reviewed the information submitted by letter dated September 3,1975, regarding the reactor cavity analysis for WPPSS 1 and 4.
We have determined that we will need additional infor-mation before we can conclude on the acceptability of the analysis.
Enclosed is a Request for Additional Information.
It should be noted that our review is limited to the calculation of the pressure response within the reactor vessel cavity. There are other aspects of the analysis that are not within the CSB scope of responsibility.
Therefore, it is suggested that the Analysis Branch and the liechanical Engineering Branch be included in the review of this TAR. AB should be responsible for reviewing the analytical model used to calculate the mass and energy release from the primary system. f!EB should be responsible for reviewing the acceptability of the location, type, and size of the postulated pipe breaks and the design of the reactor vessel support structure.
Orlainal stened 'r; Robert L. Tadesco Robert L. Tedesco, Assistant Director for Plant Safety Division of Systems Safety
Enclosure:
As stated cc:
R. Heineman S. Varga DISTRIBUTION COPIES:
S. llanauer J. Shapaker NRR READING W. ?!cDonald J. Kudrick CSB READING J. Stolz T. Greene PS READING T. Cox J. Glynn DOCKET FILE (CENTRAL FILE)
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REQUEST FOR ADDITIONAL INFORMATION WPPSS 1 & 4 i
1.
In the event of a pipe rupture inside the reactor cavity, the initial blowdown transient would lead to nonuniform pressure loadings on both the structures and enclosed components. To assure the integrity of the structures and component supports, we request that you perform a compartment multi-node pressure response analysis to provide the following information:
a) Describe the nodalization sensitivity study performed to deternine the minimum number of volume nodes required to conservatively predict the maximum pressure within the compartments. The nodalization sensitivity study should include consideration of spatial pressure variation; e.g., pressure variations circumferentially, axially and radially within the reactor cavity. Since your code does not account for the inertia term in the momentum equation, describe the adcquacy of your nodalization sensitivity study.
b) For each flow path provide an L/A (ft-I) ratio, where L is
'the average distance the fluid flows in that flow path and
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i A is the effective cross sectional area.
c) Discuss the manner in which movable obstructions to vent flow (such as insulation, ducting, plugs, and seals) were treated.
Provide analytical and experimental justification that vent areas will not be partially or completely plugged by displaced l
objects. Discuss how' insulation for piping and components was I
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considered in determinin's volumes and vent areas.
d) Discuss the potential for and the effects of missiles generated
" when the vents are cleared. Discuss the extent to which insulation in the vicinity of the break may be stripped from piping and components and evaluate the potential for this loose insulation and other' debris to clog drains leading to the sump and the sump
- screen, e) Graphically show the pressure (psia) and differential pressure (psi) responses as functions of time for enough nodes to determine
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the spatial pressure variation. Discuss the basis for establishing the differential pressures on structures'and components.
f) Discuss whether the design differential pressure is uniformly applied to the reactor cavity or whether it is spatially varied.
g) If the design differential pressure varies depending on the prox-imity 'of the pipe break location, discuss how the vent areas and flow coefficients were determined to assure that regions removed from the break location are conservatively designed.
l h) -Provide the peak transient pressure distribution on the reactor l
supports used to establish the acequacy of the design (both verti-cally and horizontally). Provide the projected area which was used l
to calculate these pressures and the location of the resultant forces.
- 1) Provide the reference used to determine the loss coefficient and i
discuss how the vena 'contracta loss is accounted for.
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