ML20127L389
| ML20127L389 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 01/22/1993 |
| From: | Beckman W CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9301270131 | |
| Download: ML20127L389 (5) | |
Text
C I/
O ConsumEIS Wimam L Beckman 1%nt Manayr POWERING MKNNiAN'$ PROGRE55 Big Rock roint Nuclear Plant,10269 US-31 North, Chattevoix, MI 49720 January 22, 1993 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT -
RESPONSE TO EXAMINATION REPORT 50-155/0L-92002 The subject Requalification Examination report dated December 24,;1992, discussed a weakness with regard to 1) the classification of an ATWS as.a site' c
area emergency when the reactor is successfully scrammed prior to entry into the ATWS_ contingency procedure, and 2) the reporting of emergency conditions as required-by 10 CFR 50.72 when the emergency' condition lasts for only a _
short period of time. _With respect to these concerns, the report requested that Consumers Power Company provide a response within.30 days describing our assessment of the identified weaknesses, the corrective actions, _if 'any, _that.
have been taken or planned to be taken, and the expected. completion date for implementation of the corrective actions.
The following provides our response as requested.-
Description of~ Weaknesses 1)
The licensed operator training program does not provide adequate guidance; on the conditions that constitute an ATWS.
Specifically,'a failure of the reactor to scram when required is only considered an ATWS condition when entry into the ATWS contingency procedure is made. As a result, a manual reactor scram due to a' failure of.the reactor to scram - _
automatically is not considered--an ATWS, and-therefore would not be i
i classified as a site-area emerge _ncy in accordance'with.the facility's emergency plan. This weakness was discussed with and wi_11 be reviewed by-the facility to determine corrective actions, if'any, that will be taken to address the weakness. '
~
2)
The' licensed operator training program does not provide adequate guidance to ensure events requir_ing notification to the NRC-in accordance _with 10 CFR 50.72 are reported. Specifically, the guidance provided for a condition (such-as an A1WS), which is classified as a' site area-emergency, would cot' be reported if the_ condition:was corrected before making an NRC_ notification.
The weakness was discussed with and will be reviewed by the_ facility to determine corrective actions,' if any, that' will be' taken.to ensure licensed operators properly report events-in -
1
-l k:
gegrdagewith10:CFR50.72.
9301270131:930122-
, (ggg gygyygy(gyp,yy
- n hDR :ADOCK'O S:
NUCLEAR REGULATORY COMMISSION 2
BIG ROCK POINT PLANT RESPONSE TO EXAMINATION REPORT 92-002 January 22, 1993 Assessment of item 1 With respect to Reactor Protection System (RPS) failure events (ATWS), the Big Rock Point SEP Implementation Procedures provide the following classification guidance (EAls):
EAL Event Classification
. Failure to SCRAM but reactor ATWS Unusual Event subcritical and not more than 23 notches not fully inserted
. Failure to SCRAM but reactor ATWS Alert subcritical and more than 23 notches not fully inserted
. failure to SCRAM and still ATWS Site Area critical or unknown Emergency
. Failure to SCRAM and reactor ATWS with General water < 2'9" above core probability Emergency of Core Damage Consumers Power believes that the judgement difficulty that was encountered during the exercise scenario primarily dealt with two questions.
1)
Does a RPS failure to automatically actuate, but immediate successful manual Scram (indicative of sensor failure) constitute an ATWS?
2)
If assuming so, does this situation warrant classification and extensive actions associated with a " Site Area Emergency"?.
10 CFR 50.62(b) defines an " Anticipated Transient Without Scram" (ATWS) as an anticipated operational occurrence as defined in Appendix A of this part g
followed by the failure of the reactor trip portion of the protection system I
specified in General Design Criterion 20 of Appendix A of this part.
1 We believe that based upon the above, which subsets ATWS failures to "the reactor trip portion of the protection system," that sensor / protection system input failures, followed by successful manual scram would not constitute an ATWS.
In reviewing 10 CFR 50.62 and NUREG-0460, an ATWS might be better described as a failure to shutdown the reactor by control rod insertion thus requiring power reduction by one or more mitigation features required by 10 CFR 50.62.
The features for a BWR would include:
Recirculating Pump Trip Alternate Rod Injection Standby liquid control system I
m.
.'NUCL nR REGULATORY COMMISSION 3
BIG ROCK POINT PLANT RESPONSE TO EVALUATION REPORT 92-002 January 23, 1993 This thought process was prevalent prior to the issuance of system-based E0P's where the event based Emergency Procedure for ATWS at Big Rock Point, described an ATWS as:
Reactor Scram setpoint exceeded All control drives not inserted Reactor Power greater than 4%
Reactor Pressure at or above 1360 psig These symptoms support the concern that a Reactor Scram should have occurred but an insufficient number of control rods were inserted to lower reactor power sufficiently to reduce reactor pressure which requires prompt mitigative actions.
Successful Manual Scram after an automatic initiation failure would not constitute an event meeting this level of concern.
In reviewing Appendix 1 of NUREG-0654; FEMA-REP-1; Rev 1, " Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants," the guidance within would require classification of an ATWS event as a Site Area Emergency if the situation constituted a:
" Transient requiring operation of shutdown systems with failure to scram (continued power generation but no core damage immediately evident)."
A successful manual Scram in response to a failure of the reactor to Scram automatically, would not result in continued power generation, thus would not meet the guidance for a Site Area Emergency.
In conclusion, Consumers Power believes that the guidelines in the Emergency Plan Implementing Procedures led to the questions concerning classification of this scenario event and not a licensed operator training program inadequacy.
Consumers Power does agree that this type of event would require Site Emergency Plan activation but not at a " Site Area Emergency" level.
Examinee concern that a declaration of Site Area Emergency for a failure which was promptly mitigated may have contributed to the confusion in classifying the event.
Corrective Actions Consumers Power believes that changes to the Big' Rock SEP Implementation Procedures for classification of emergencies in this area are warranted.
Improvements which follow the guidance in NUREG-0654 can eliminate ~the confusion surrounding classification of ATWS events.
At this time, Big Rock Point personnel support the following changes to the EAL's for ATWS events:
' NUCLEAR REGULATORY COMMISSION 4
1 BIG. ROCK POINT PLANT i-RESPONSE TO EVALUATION REPor.T 92-002 January 23, 1993 EAL Event Classification
. Reactor Protection System (RPS)
RPS Input Unusual Event Failure requiring Manual Scram Failure to insert control rods
. Reactor Scram Failure following ATW3 Alert automatic and manual RPS actuation and reactor power > 5%
L
. Reactor Scrata Failure ATWS Site Area requiring boron injection Emergency
. Reactor Scram Failure, ATWS with General reactor power >5%, and probability Emergency reactor water <2'9" above for Core Damage core These EAL's closely align with the mitigative actions outlined in the BRP
'uld minimize operator confusion.
E0P's 6
Following Region III review and concurrence with this approach, the required 4
Emergency Plan and Implementing Procedure changes will be initiated in accordance with 10 CFR 50.54(q).
It is expected that these changes will be submitted within 60 days following Region III concurrence with our response to the weakness.
In the interim, a letter (Attachment 1) has been sent to all Shift Supervisors and Site Emergency Directors discussing the identified weaknesses and expected actions.
Assessment of Item _1 q
In the past, hift Supervisors and Site Emergency Directors have not demonstrater eifficulty in identifying reportable events in accordance with 10 CFR 50.72.
50.72_ requires reportability of all Site Emergency Plan-activations within one hour and Plant Implementing Procedures address this requirement. Consumers Power Company believes that in this case, the difficulty as discussed above was in deciding that the scenario warranted an emergency classification, not whether or not a phone notification was needed.
Had the examinees activated the emergency plan, phone notifications would have been made. The changes to the EAL's discussed above should improve the classification of ATWS events insuring reportability when required.
Although Consumers Power Company would nos have expected this action during a training scenario, had an RPS failure occurred that didn't result in an SEP activation, s
as a minimum the event would have been reported per 10 CFR 50.72(b)(2)(iii).
. NUCLEAR REGULATORY COMMISSION 5
Bla ROCK POINT PLANT
- RESPONSE TO EVALUATION REPORT 92-002 January 23, 1993 Two examples of good performance in dealing with short duration events are discussed in Region 111 Inspection Report 87-028 dated December 23, 1987. On January 31, 1987 at-0440 hours smoPe was observed in the station power room.
An " Alert" was declared at 0445 hour0.00515 days <br />0.124 hours <br />7.357804e-4 weeks <br />1.693225e-4 months <br />; and terminated four minutes later. On June 23, 1987 a fire alarm was received at 0321 hours0.00372 days <br />0.0892 hours <br />5.30754e-4 weeks <br />1.221405e-4 months <br /> due to an overheated dehumidifier cord. The Shift Supervisor declared an Alert at 0325 hours0.00376 days <br />0.0903 hours <br />5.373677e-4 weeks <br />1.236625e-4 months <br />, activated portions of the plan and terminited at 0440 hours0.00509 days <br />0.122 hours <br />7.275132e-4 weeks <br />1.6742e-4 months <br />. As discussed in the report, the Inspectors reviewed th documentation related to these events and concluded that classifications and notifications had been performed promptly and within time frame goals.
r Although Consumers Power Company does not believe any corrective action (including operater training program changes) is warranted in this area, the interim memo attached to this letter provides a reminder of reporting expectations to the responsible personnel.
Should any questions or concerns arise regarding this response, please contact us.
illiam L Beckman William L Beckman Plant Manager CC: Administrator, Region Ill, USNRC NRC Resident Inspector - Big Rock Point ATTACHMENT
- - _ - _ _ _ _ _ _ _ - _ _ _ _