ML20235F172
| ML20235F172 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 06/30/1987 |
| From: | Larson C NORTHERN STATES POWER CO. |
| To: | Hehl C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 8707130250 | |
| Download: ML20235F172 (5) | |
Text
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I Northern States Power Company t
414 Nicollet Mall Minneapolis Minnesota 55401 1
June 30, 1987 Telephone (612) 330-5500 l
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Mr Charles W Hehl, Chief Operations Branch U S Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 1
PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License No. DPR-42 50-306 DPR-60 Response to Generic Weaknesses Identified in NRC Region III Examination Reports No. 50-282/0L-87-01 & 50-306/0L-87-01 This letter is in reply to your letter of May 11, 1987, which forwar-ded Examination Reports No. 50-282/0L-87-01 and 50-306/0L-87-01 for the Prairie Island Facility. We were requested to provide a written response to generic weaknesses noted during the administration of simulator examinations conducted on March 23 - 27, 1987 at the Prairie Island Facility and described in the Examination Reports.
Weakness Senior Reactor Operators (SRO's) in general, did not take command of control room activities during abnormal or emer-gency conditions.
Response
Reviews of selected simulator exam reports and discussions with Mr J A Lennartz of your Staff indicate that SRO's did not ensure adequate positive control of the process used to trip instrument bistables following instrument failures.
Also, during several events Reactor Operators (RO's) diag-nosed events and took corrective action without being direc-ted to do so by the SRO.
In some events the SRO did not respond immediately to alarm conditions.
A revised technique to control the tripping of instruments-tion bistables during simulator training sessions is being developed and will be implemented by July 1, 1987.
In ad-dition, plant operations is reviewing the need for additional I
procedures or controls.
If additional procedures or controls are warranted, they will be implemented by January 1, 1988.
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C W Hehl Northem States Power Company June 30, 1987 Page 2 The importance of SRO's demonstrating command of control room activities during abnormal or emergency events will be empha-sized in future simulator training sessions.
In addition, j
the number of simulator training hours each SRO candidate receives prior to the NRC examination will be increased from 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> to more than 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. These changes will be imple-
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mented prior to the next SRO training program which is sched-1 uled to begin during July 1987.
1 A contributing factor to this observed weakness may have been the addition of diagnostic and team skills training to the training program. This training was included in the program through the initiatives of NUMARC and INFO.
This training emphasizes the team approach to solving problems.
Under this approach, the SRO acts more as a manager and less as a com-
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mander.
The SRO is expected to act as part of the team, but j
will intervene only when actions of the RO's are not approp-l riate. We find this team approach to be more effective in
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dealing with the complexities of multiple malfunctions on the
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simulator, and we plan to continue diagnostic and team build-I ing training in the SRO program.
However, we will modify this training to ensure that leadership is demonstrated by the SRO.
This modification will be implemented prior to the next SRI training program which is scheduled to begin during l
July 1987.
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Weakness j
i RO's were inattentive of control board conditions and as a result, their actions were generally reactive in nature, not preventative. Abnormal board conditions existed for extended periods of time and were not addressed until the condition degraded to an alarm setpoint.
Response
i Discussions with Mr J A Lennartz of your Staff indicated that R0ia failed to observe abnormalities in the following param-eters prior to alarm actuation:
condenser vacuum, steam generator steam flow, pressurizer spray valve demand, con-tainment humidity, and closed turbine intercept valve.
RO's are trained to maintain an observation of available l
control room instrumentation including alarms, plant computer
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system, and emergency response computer system (ERCS).
Al-j though it is desirabh for the RO to observe abnormalities in all available parameters, it becomes very difficult to l
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C W Hehl Northem States Power Company June 30, 1987 Page 3 observe these abnormalities when examiners are asking ques-l tions during the simulator evaluations. Also, because the plant process computer and ths ERCS have not yet been fully installed in the simulator, RO's are trained to give more l
attention to those parameters used to monitor critical safety functions. None of the parameters listed by the examiner are used to monitor critical safety functions.
The ERCS computer will be installed in the simulator by De-cember 31, 1987, and the plant process computer should be installed in the simulator by December 31, 1988.
Weakness Operators were time conscious of simulated events.
Instances were noted where candidates stated, "the ATWS should be over by now and "offsite power should be back by now" which indi-cated to the examiners that the candidates were trained in such a way as to expect transients to conclude in a set peri-od of time.
At the exit interview, the training supervisor stated that in an ATWS condition, "I could leave the control room and trip the rod drive MG sets in 10 seconds." Since the training supervisor believed that an ATWS may easily and quickly be remedied, the examiners observation that the can-didates were trained to expect transients to conclude in a set period of time may be valid.
Response
In future simulator training sessions, the time at which transients are terminated will be varied.
These changes will be implemented by July 1, 1987.
During simulator training it is important to create a control room environment that is as real as possible.
Part of this realism is to accurately simulate the response of auxiliary operators.
When an auxiliary operator is called on to per-form an action on the simulator, it is important that the action occur in a realistic amount of time.
If the scenario calls for the outplant action to be unsuccessful, then con-trol room personnel should be informed that the action was unsucesasful or they should investigate why the action has not been completed. We believe that operators who are aware j
that expected actions have not occurred in a timely manner and take alternative actions exhibit good operational tech-i nique.
t C U Hehl Northern States Power Company June 30, 1987 Page 4 Weakness Operators did not conform to Red Path Procedure FR-S.1, ATWS.
Specifically, Step 1 of FR-S.1 requires the operator to drive rods into the reactor core.
Step 4 requires the initiation of emergency boration.
Several instances were noted where i
the operator driving the rods, stopped driving rods several times to initiate emergency boration while the reactor was still at power.
The examiners discussed with the licensee their position that the RO should remain at the console dri-ving rods, and the lead RO should initiate emergency bora-tion.
The other area where FR-S.1 was not followed was the way in which the candidates tripped the rod drive MG sets from the control room.
If the auxiliary operator that had been dis-patched to locally trip the MG sets took an excessive amount of time to accomplish this function (in one instance this was 5 minutes), the candidates rapidly opened then closed break-ers 13-3 and 14-2.
This deenergized the busses supplying the rod drive MG sets and dropped the rods, effectively termina-ting the ATWS situation.
There are two potential problems with this, one being that it is not in the procedure.
The second problem with deenergizing the busses is the potential loss of all other equipment powered off the busses if that bus failed to re-energize.
Response
The simulator training program will be modified to have the lead reactor operator initiate emergency boration when exer-cising FR-S.1.
However, should the lead reactor operator have difficulty completing Steps 2 and 3 of FR-S.l. the RO will be trained to stop driving rods for the few seconds necessary to initiate emergency boration.
These changes to the simulator training program will be implemented by July 1, 1987.
With regard to tripping of the source breakers to the rod drive MG sets from the control room during an ATWS, we be-lieve the candidates exercised sound judgment in this partic-ular instance.
The scenario did not allow the auxiliary operator action of tripping the MG sets locally to occur in a timely manner and consequently the scenario was outside the scope of the procedure. Whenever a situation exists that requires action, but is not covered by written procedures,
C W Hehl Northem States Power Company June 30, 1987 Page 5 the operator must be allowed to exercise his judgment.
The existing FR-S.1 procedure is designed to provide multiple means of inserting negative reactivity into the core follo-wing a failure of the reactor protection system. We do not believe additions to the procedure are needed.
Weakness SRO's and RO's generally did not communicate well during the simulator scenarios.
Response
Discussions with Mr J A 1.ennartz of your Staff indicate that the primary contributor to this weakness was that RO's were not informed by the SRO that instrument bistables were about to be tripped following instrument failures. As stated in the response to the first weakness, a revised technique to control the tripping of instrumentation bistables during simulator training sessions is being developed and will be implemented by July 1,1987. As part of this technique, improved communication between the SRO and the RO will be emphasized.
Please contact us if you have any questions related to our planned actions to resolve the deficiencies and concerns noted in your May 11, 1987 Examination Report, e
C E Lars q,j Vice President Nuclear Generation c: Regional Administrator, Region III, NRC Sr Resident Inspector, NRC Sr Project Manager, NRC I
G Charnoff
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