ML20045E777
| ML20045E777 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 06/08/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| NUDOCS 9307060031 | |
| Download: ML20045E777 (4) | |
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c/s/93 A
Loose Ends Re: HRA Insights 1.
The list of Critical Tasks in Section 19 D.7.6, " Summary of Important Operator Actions", is incomplete, and does not reflect all items that are identified as important in other sections of the SSAR.
In this regard please address the need for the following modifications to the list.
a.
Add " align firewater for injection into RPV" This action (ARV) is discussed in 19D.7.2 but is not included on the list (it is presently only on the list with regard to seismic.)
The action is critical to both prevention and mitigation and should be on list.
b.
Modify 1(e) to specifically include depressurizing following loss of RCIC as a result of battery depletion (e.g., Class 18-2 sequences).
This action is important to assuring that reactor vessel failure in 9$
long term station blackout sequences occurs at low pressure.
c.
Add "close ECCS valves that opened as a result of accident conditions" (Discussion in 19D.7.3 says that emergency procedures are needed for this action.)
d.
Aud (for floods in the turbine building): " isolate the leak and shut down the plant without losing condenser vacuum to avoid a turbine trip without bypass scenario" (This is flagged as an important insight from the analysis in 19R.6.2.)
This action should also be reflected in 19R.6.4.
e.
Include on the " Critical Tasks" list, those items on the COL Procedures and Planning list (19D.7.6) and in the COL License Information section of the SSAR (19.9) that also require consideration as part of the human factors evaluation.
(Just because an item is identified in the aforementioned list /section does not mean that it need not be addressed in the human factors evaluation, or in training activities.)
2.
There is some confusion regarding the role of the " COL Procedures and Planning" list in SSAR Section 19D.7.6, and the " COL License Infornation" provided in SSAR Section 19.9.
TFe information provided in SSAR Section 19.9 appears to be more complete and comprehensive.
However, some actions in Section 19D.7.6 have been omitted in Section 19.9, e.g., opening of doors / hatches to divert water in an internal flood. More importantly, it appears that the human factors evaluation (and identification of Critical Tasks) is keying only on the information provided in Sectica 19D.7.
Please modify the SSAR to eliminate this ambiguity.
Replacing the list of COL Procedures and Planning in SSAR Section 19D.7.6 with a reference to an appropriately modified Section 19.9 is one possibility.
3.
SSAR Sections 19D.7.2 and 19D.7.3, last paragraph - In both sections, request that closing sentence be modified or removed.
Several of the actions referred to are still risk significant, e.g., using drywell sprays.
These sentences tend to characterize these actions as ones that 7
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I a COL-applicant need not concern themselves with.
Clearly this is not the case.
4.
Section 19Q.12.3 (Shutdown Study) provides a list of tasks for which procedures should be prepared. However, with few exceptions, these tasks do not appear to have been reflected in either the Critical Task list, or the COL Procedures and Planning list in SSAR Section 19D.7, e.g., (1) use of freeze seals, (2) increasing CRD pump flow when using for inventory control, and (3) ensuring that one safety division is always available with intact fire / flood barriers.
Each of these items needs to be more clearly dispositioned in either 19Q.12.3 or 19D.7.6.
5.
SSAR Section 19Q.12.3 provides a list of functions for which instrumentation must be made available during shutdown.
GE needs to confirm: (1) that the corresponding instrumentation included in the minimum inventory of controls, displays and alarms, and (2) that there is a vehicle for assuring that these instruments will be available-during shutdown (e.g., technical specifications).
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,l Additional Loose Ends on HRA (6/24/93) 1.
Please provide the HEP name/ identifier for each of the three errors discussed in Section 19D.7.3 f
2.
In 19D.7.10.2, the seque ;s/cutsets that contain 4 or 5 HEPs include two errors which are not presently described except by title -- RHRCFER and ROOIOPHL.
These sequences with multiple HEPs actually dominate CDF in the sensitivity analyses. Accordingly, provide: (1) a more detailed description of these two errors and the basis for their quantification, and (2) the rationale for not including these as "important actions".
Note: Table 18.E.2.1, part V.I.c (in 10/23/92 version of SSAR Appendix 18E) states that i
' human actions which are identified through PRA sensitivity analyses to have significant impact on safety shall also be considered " critical" tasks'.
This would imply that i
these two actions should be included on the list.
3.
Provide the basis for the sentence in SSAR Section 19.13.5 (draft amendment faxed to us 12/14/92) that the " contribution of human errors was compared to the contribution from an operating plant and found to be substantially lower".
The comparison should be 3
discussed in Section 19D.7.
n 4.
It appears that four general provisions are to be made for all human actions on the
" critical tasks" list (clear unambiguous indication, capability to perform in a straightforward manner, clear written procedures, training), however, this is not clearly stated in the SSAR.
Rather, the provisions are discussed on an error by error basis and seem to be slightly different and non-uniform.
Furthermore, for some errors (e.g., the initiation of sprays in response to suppressien pool bypass discussed in 1
19D.7.3, the use of condensate injection discussed in 19D.7.4.4, and the isolation of flood sources discussed in 19D.7.5.2), it appears that something less than the four provisions will be made. A similar situation exists with regard to the human actions that are to be addressed by the COL via procedures and planning.
In this case, the commitment to provide associated training and instrumentation / alarms is non-uniform and unclear.
Please provide clarification regarding minimal provisions that will.be made for all critical tasks, and all " COL Procedure and Planning" items. This should include specifying " generic" provisions applicable to all actions within each of the 4 categories, and then providing additional information (such as locations from which actions _will be able to be taken, actions for which access to valves actions must be provided, actions that would be trained on simulator, actions for which indication and l
alarms would be provided) on an item by item basis, possibly in the form of a footnoted summary table or matrix.
5.
On the surface, the categories " COL System Operating Procedure" and " COL Procedures and Planning" in 19D.7.6 appear to involve the same COL actions / requirements.
Please describe the dif ferences between the procedures and provisions that would be developed l
for each category.
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6.
Describe what was done by GE to address the concern raised in DSER Chapter 19, Section 3.7.2.5 regarding some event tree branches depicted as hardware failures that should have included a human action component but didn't.
Specifically address the example cited % the DSER (failure to recover offsite power or diesel).
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