ML20057A636
| ML20057A636 | |
| Person / Time | |
|---|---|
| Issue date: | 08/31/1993 |
| From: | Boger B Office of Nuclear Reactor Regulation |
| To: | England L BWR OWNERS GROUP |
| References | |
| NUDOCS 9309150084 | |
| Download: ML20057A636 (3) | |
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August 31, 1993 Mr. L. A. England, Chairman BWR Owners' Group c/o Gulf States Utilities Company P.O. Box 220 St. Francisville, LA 70775
Dear Mr. England:
SUBJECT:
COMMENTS ON BWR OWNERS' GROUP SIMULATOR SCENARIO DEVELOPMENT GUIDELINE On June 30, 1993, I and members of my staff met with you and other representatives from the BWR Owners' Group (BWROG) and the Nuclear Management and Resources Council (NUMARC) to discuss the industry's initiative in the area of dynamic simulator scenario development for BWR requalification examinations. As a result ;f the discussions, it was agreed that my staff would review the details of the proposed methodology and provide feedback to the BWROG.
In a letter dated July 19, 1993, you provided a copy of the "BWR Owners' Group Simulator Development Guideline" and requested a formal review to ensure the guidance does not conflict with the Examiner Standards, NUREG-1021. The purpose of this letter is to provide comments on revision 0 to the aforementioned guideline.
We believe that the BWROG effort is commendable and should have a positive impact on critical task identification and promote simulator examination consistency. However, we do have three concerns, as described below.
First, section 1.0 of the guideline indicates the use of the templates, along with the corresponding critical tasks, :;hould promote a consistent level of dynamic simulator scenario difficulty and evaluation between BWR facilities and the NRC regional offices.
We are in overall agreement with the intent of the guideline to specify criteria for critical task identification and accomplishment in terms of plant conditions and procedural usage. However, we are concerned that the guideline's template methodology alone will be adequate to ensure only simulator scenarios of consistent and sufficient scope, depth, and complexity are developed.
To promote consistency in the level of difficulty of scenarios, we suggest that the guideline be revised to require evaluation of scenarios using the qualitative and quantitative attributes of the Examiner Standards, NUREG-1021.
Second, section 3.1.2 states that if it is determined that the scenai!o malfunctions have created a scenario arriving at multiple endpoints in the Emergency Procedure Guidelines (EPGs) simultaneously, the scenario falls cutside the scope of the templates and shall not be used for evaluations.
Also, section 3.2.2.5 states that the combination of malfunctions shall not cause the scenario to be driven down parallel paths to achieve more that one endpoint.
However, there are credible scenarios where the use of multiple l
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.N Mr. L. A. England, Chairman August 31, 1993 endpoints is appropriate as long as there is a success path.
For example, BWR Scenario Two (Power Oscillations with an ATWS), as discussed in ES-604 of i
NUREG-1021, is an acceptable scenario with multiple endpoints (RPV 5 and RPV 1).
We believe that scenarios with more than one endpoint are acceptable and meet the intent of NUREG-1021.
j Finally, section 3.2.3 of the guideline indicate:: the identified critical tasks were developed using the process describei in NUREG-10:1 and the technical basis of the BWR EPGs. However, while the guidelita provides i
justification for the selection of the critical tasks, we believe that it may be premature to eliminate from consideration as critical all other tasks in the EPGs. There may be cases where improper crew performance of a task could satisfy the critical task criteria prescribed by NUREG-1021, but not i
be considered critical per the proposed methodology of the guideline.
For example, a scenario could be designed consistent with the endpoint of PC-5, LOCA - Drywell Containment Spray, such that suppression chamber / torus spray is effective in reducing containment pressure with drywell/ containment spray failed or inoperable.
Failure of the crew to properly initiate suppression chamber / torus spray could then result in significant degradation in the mitigative capability of the plant and an unnecessary emergency i
depressurization (PC-6, LOCA - Emergency Depressurization - Pressure Suppression Pressure).
We believe that additional latitude in this regard is necessary to ensure no critical tasks are overlooked and recommend that the i
criteria of section 3.2.3 be broadened to allow for the selection of critical tasks based solely on the critical task methodology of NUREG-1021.
i In accordance with 10 CFR 2.790 of the Commission's regulations, a copy of this letter will be placed in the Public Document Room.
Should you have any questions, please contact Mr. Robert M. Gallo, Chief, Operator Licensing Branch, at (301) 504-1031.
Sincerely, ORIGIFAL SIGFD BY Bruce A. Boger, Director Division of Reactor Controls and Human Factors Office of Nuclear Reactor Regulation cc:
R. Whitesel, NUMARC Distribution:
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Mr. L. A. England, Chairman August 31, 1993 endpoitits is appropriate as long as there is a success path.
For example, BWR Scenario Two (Power Oscillations with an ATWS), as discussed in ES-604 of NURE0-1021, is an acceptable scenario with multiple endpoints (RPV 5 and RPV.').
We believe that scenarios with more than one endpoint are acceptable and meet the intent of NUREG-1021.
Finally, section 3.2.3 of the guideline indicates the identified critical tasks were developed using the process described in NUREG-1021 and the technical basis of the BWR EPGs. However, while the guideline provides justification for the selection of the critical tasks, we believe that it may be premature to eliminate from consideration as critical all other tasks in the EPGs. There may be cases where improper crew performance of a task could satisfy the critical task criteria prescribed by NUREG-1021, but not be considered critical per the proposed methodology of the guideline.
For example, a scenario could be designed consistent with the endpoint of PC-5, LOCA - Drywell Containment Spray, such that suppression chamber / torus spray is effective in raducing containment pressure with drywell/ containment spray failed or inoperable.
Failure of the crew to properly initiate suppression chamber / torus spray could then result in significant degradation in the
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mitigative capability of the plant and an unnecessary emergency i
depressurization (PC-6, LOCA - Emergency Depressurization - Pressure Suppression Pressure). We believe that additional latitude in this regard is necessary to ensure no critical tasks are overlooked and recommend that the criteria of section 3.2.3 be broadened to allow for the selection of critical tasks based solely on the critical task methodology of NUREG-1021.
In accordance with 10 CFR 2.790 of the Commission's regulations, a copy of this letter will be placed in the Public Document Room.
Should you have any questions, please contact Mr. Robert M. Gallo, Chief, Operator Licensing Branch, at (301) 504-1031.
Sincerely, ORIGIFAL SIGYD BY Bruce A. Boger, Director Division of Reactor Controls and Human Factors Office of Nuclear Reactor Regulation cc:
R. Whitesel, NUMARC Distribution:
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