ML20035H333
| ML20035H333 | |
| Person / Time | |
|---|---|
| Issue date: | 04/28/1993 |
| From: | Rosalyn Jones Office of Nuclear Reactor Regulation |
| To: | Beckner W Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9305040238 | |
| Download: ML20035H333 (2) | |
Text
r-h4 April 28.1993 HEMORANDUM FOR:
William D. Beckner, Chief Probabilistic Safety ~ Assessment Branch Division of Systems Safety and Analysis FROM:
Robert C. Jones, Chief Reactor Systems Branch Division of Systems Safety and Analysis
SUBJECT:
GE SUBMITTAL OF SSCs TO BE INCLUDED IN THE ABWR DRAP AND ORAP PROGRAMS BASED ON PSA INSIGHTS (RCJ 79) i We reviewed the GE submittal sent to us by your memo dated March 29, 1993. The approach by GE to identify elements of the RAP through application of risk importance measures appears largely reasonable. We have identified some specific comments as requested on RAP elements for SSCs which are provided below.
As a general comment, we note that the PRA did not include modeling of Shutdown conditions, therefore, risk measures can not be calculated. Rather GE completed a deterministic evaluation on pages 19K-11,12 to identify Shutdown importance.
l The important SSCs identified for the Shutdown Analysis are not complete. The following systems should be added to the SSCs:
Emergency diesel generators, l
combustion gas turbine, and the Fuel Pool Cooling Systems. Additionally, GE took credit for using tha Reactor Water Clean-up System to provide alternate decay l
heat removal and the feedwater and condensate system to provide alternate make-up capability under certain plant condition during low-power and shutdown operations. Therefore, these systems should also be included in the SSCs.
SPECIFIC COMMENTS:
l 1.
ATWS or ATWS mitigation equipment is not addressed in the list of SSCs for l
CDF except for Seismic Analysis. It is not clear why ATWS is excluded in the i
GE study.
2.
Page 19K-6, fourth paragraph it is stated that "The COL applicant should assure that maintenance and test activities for risk-significant components in the FW system, the FW pumps and motors, are appropriate to assure high reliability." But the table 19K.ll-1 where recommended maintenance and test intervals are specified do not include the FW system.
3.
In the table 19K.3-1, RCIC minimum flow valve E51-F011 is listed as risk j
significant but not the pump suction valves E51-F001 or E51-F008. It is not clear why the minimum flow valves are more risk significant than the pump l
suction valves.
1 4.
In Table 19K.11-1, Page 19K-28, the RHR flow meters are included in the i
table.
Identify which flow meters are to be included so it is possible to i
understand the significance of these flow meters.
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1 5.
RCIC steam line inboard ai.d outboard isolation valves are not included in the study even though they could be closed due to spurious isolation signals.
6.
Section 19K.5-In the list for Important Structures, Systems and Components for Seismic Analysis, RCIC is not included. Why is RCIC excluded?
7.
Section 19K.9-It is stated that "A single train of each of these systems should be designated for RAP by the COL applicant". We disagree. Complete systems should be designated for RAP to assure the system reliability.
8.
19K.10- Identification of important Capabilities Outside the Control Room.
Manual operation of the RCIC from outside the control room is included even though RCIC controls are not in the Remote Shutdown Panel. We would like GE to explain in detail how RCIC can be operated from outside the control room.
.yh'miai7 G N!
pj)pt C.hnt:;
Robert C. Jones, Chief Reactor Systems Branch Division of Systems Safety & Analysis cc.
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