ML20039B110
| ML20039B110 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 12/18/1981 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.2, TASK-3.A.1.2, TASK-3.A.2.2, TASK-3.D.3.4, TASK-TM NUDOCS 8112220300 | |
| Download: ML20039B110 (6) | |
Text
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Consumers e
David P Hoffman hulcar tsanung AJmmhtrator Company General offices. 1945 West Parnait Rocd, Jackson, MI 49201 e ($17) 788-1636 December 18, 1981 DJ Dennis M Crutchfield, Chief
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Operating Reactors Branch No 5 Nuclear Reactor Regulation WCCi;g US Nuclear Regulatory Commission P
DEC2179973 Washington, DC 20555
[.h DOCKET ','0 2 155 - LICENSE DPR BIG ROCK POINT PLANT - FINAL
\\ >x gN N/,g/ W \\- - W' RESPONSE TO NUREG-0737 ITEMS II.B.2.,
III.A.1.2, III.A.2, & III.D.3.4 Consumers Power Company letter dated October 21, 1981 requested an extension of the submittal date for our final responses to NUREG-0737 Items II.B.2, III.A.1.2, and III.A.2, among others. The areas to be addressed in these final responses were discussed in the update to our response to NUREG-0737 for Big Rock Point (Consumers Power Company letter dated July 9, 1981). Now that the required analyses and associated reviews specified in our previous corres-pondence have been completed, this letter provides Consumers Power Company's final response to NUREG-0737 Items II.B.2, III.A.1.2, and III.A.2.
This letter also provides our final response to NUREG-0737 Item III.D.3.4 since, as explained in our NUREG-0737 response update, the requirements of Item III.D.3.4 are also addressed in our response to Item III.A.I.2.
Because the revised analysis of radiation doses following an accident involving serious core damage and the asociated shielding design review are common to the responses to all four items, the results and conclusions are presented in two parts. The first part consists of a summary discussion of the results of analysis and review of the doses to plant personnel should an accident involving serious core damage occur. The details of this analysis will be included in a forthcoming revision to the Big Rcck Point Probabilistic Risk Assessment (PRA)._ revision. The second part provides the specific responses to the NUREG-0737 Items II.B.2, III.A.1.2, III.A.2., and III.D.3.4.
As a result of the Big Rock Point PRA, Consumers Power Company has proposed to perform specific modifications which were shown to reduce the number of dominant accident sequences and the probability of core damage occurring.
In the following discussion concerning radiation fields and personnel exposure, credit has been taken for these modifications.
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8112220a00 811210 PDR ADOCK 05000155 P
F Dennis M Crutchfield, Caief 2
Big Rock Point Plant December 18, 1981 I.
SUMMARY
OF RADIATION DOSE ANALYSIS AND SHIELDING DESIGN REVIEW By reviewing Plant Operating Procedures, Emergency Procedures, the Site Emergency Plan, and holding discussions with plant operators, the actions taken by plant personnel in the event of an accident involving serious core damage were determined. We found that most actions are performed prior to any significant release of radioactivity from the core.
Nevertheless, those actions which might be required to be carried out in radiation fields that are greater than normal have been assessed relative to Consumers Power Company's established dose criteria. These criteria are the following:
1.
Dose rates shall not exceed a 30-day average of 15/mr/hr for continuously inhabited areas.
2.
Plant personnel exposure shall be limited to 25 Rem for those operators performing mitigating actions outside the 15 mr/hr areas, including ingress and egress. This particular exposure limit is judged to be acceptable based on arguments presented in NCRP Report 39 entitled " Basic Radiation Protection Criteria", paragraph 259 and the " Manual of Protective Action Guides and Protective Actions for Nuclear Incidents" (EPA).
For postulated accidents during which serious core damage occurs, an evaluation of operator actions showed that neither of the dose criterion is violated.
Plant ingress or egress under the worst possible conditions (ie, total core melt one hour after initiation of the accident) would result in an exposure of 8 Rem.
Since the majority of core damage accident scenarios investigated resulted in core damage occurring at times greater than one hour after the initiation of the accident (one-half of the scenarios resulted in core damage occurring several days after accident initiation), the exposure dose will be much less than 8 Rem because of radioactive decay.
In these cases, the maximum dose would be to personnel called in to man the Technical Support Center (TSC).
Since their responsibility is mainly to assess the plant condition, notify the authorities, and direct rather than perform actions, their exposure would be limited to that which they receive while entering or leaving the plant. The assessment of radiation fields and nuclide concentrations in the plant will be carried out by personnel who are already inside the plant. Radiation fields and nuclide concentrations outside the plant will be assessed by plant personnel starting from outside the plant at a later time. Therefore these assessments will be performed in much lower radiation fields.
Plant personnel leaving the site would, in most cases, leave prior to the radiation fields reaching their maximum intensity.
If, for some reason, personnel were to leave at the worst possible time, ie, at the completion of core melt for accidents sequences in which core melt occurs rapidly, they too would receive a dose of only 8 Rem.
If these same pecple were called back to the plant, the radiation field to which they would be oc1281-0023a142
Dennis M Crutchfield, Chief 3
Big Rock Point Plant December 18, 1981 exposed would have decreased substantially because of radioactive decay during the intervening time period.
If it is assumed that the worst case event occurs and that the plant staff rotates in eight hour shifts, seven days per week, the total dose over thirty days for those people whose shift starts at the worst possible time is 14 Rem.
(This dose includes exposure during ingress, egress, and manning the Control Room or TSC). Most of this dose is the 8 Rem received while entering the plant for the first time. The total exposure will be 6 Rem for the shift personnel who arrive eight hours later, and 5.5 Rem for those who arrive eight hours after that. Most of the other operator actions will result in an exposure of less than 1 Rem.
Under worst case assumptions, some actions such as switching core spray to the recirculation mode or verifying that the core spray pumpt have started, could result personnel axposures of up to 10 Rem.
Since most of the accident scenarios were found to result in core damage occurring later than one hour after accident initiation, the exposures associated with the actions described above would be much lower. Nevertheless, one action which was found to result in high personnel dose exposure is the transporting of air sample filters to the On-site Support Center (OSC) for analysis.
If a technician uses the stairs, the dose received each time could be as high as 1 Rem. Accordingly, Consumers Power Company will investigate alternate means of transporting the air sample filters to the OSC.
Consumers Power Company has concluded, based on the results of analyzing possible plant personnel exposure to radiation fields resulting from core damage accidents summarized above, that all necessary operator actions can be performed without exceeding either of the established dose criterion.
Consequently, Consumers Power Company has not identified any need for additional shielding of vital areas in which personnel occupancy or action may be unduly limited by the radiation fields resulting from postulated accidents involving serious core damage.
II.
FINAL RESPONSES TO NUREG-0737 ITEMS II.B.2. III.A.1.2, III.A.2, AND III.D.3.4.
FINAL' RESPONSE TO NUREG-0737 ITEM II.B.2:
DESIGN REVIEW OF PLANT SHIELDING AND ENVIRONMENTAL QUALIFICATION OF EQUIPMENT FOR SPACES / SYSTEMS WHICH MAY BE USED IN POST-ACCIDENT OPERATIONS In our letter dated July 9, 1981, Consumers Power Company committed to the following:
1.
Review potential problems concerning plant ingress and egress under post-accident conditions 2.
Evaluate the need for local shielding oc1281-0023a142
Dennio M Crutchfi21d, Chiof 4
Big Rock Point Plant December 18, 1981 3.
Evaluate potential post-accident habitability problems The review described in (1) above has been completed. As explained in the preceding Summary, in the event of an accident in which serious core damage occurs, plant ingress and egress can be accomplished while maintaining doses to personnel within the 25 Rem criterion. Furthermore, in response to Items (2) and (3) above,no additonal local shielding is needed and all continuously occupied areas are habitable (dose rates average 15 mr/hr or less over 30 days).
FINAL RESPONSE TO NUREG-0737 ITEM III.A.I.2: UPGRADE EHERGENCY SUPPORT FACILITIES Consumers Power Company letter dated July 9, 1981 committed Consumers Power to submit the following information.
1.
Whether or not alternate shutdown panel readouts will be installed so that personnel manning the TSC would have access to this information.
2.
Review, evaluate, and recalculate doses to operators in the Emergency Support Facilities.
With respect to Item (1.) above, Consumers Power Company has determined that alternate shutdown panel readouts will provide no useful benefit to those in the Technical Support Center.
The actions identified in Item (2.) above have been performed and the results provided in Part I of this letter.
FINAL RESPONSE TO NUREG-0737 ITEM III.A.2:
IMPROVING LICENSE PREPAREDNESS -
LONG-TERM In our letter of July 9, 1981, Consumers Power Company committed to investiga-ting the need for supplemental meteorological information which might be necessary in order to assess the exposure of personnel ingressing or egressing the plant. As stated in the Part I Summary, plant ingress and egress under a radioactive plume resulting from the postulated worst case core damage accident will expose personnel to a dose of about 8 Rem.
Coupling this dose with additional possible doses from other sources of radiation still leads to personnel exposures within the criterion limit of 25 Rem.
Note that the people who might be exposed to this dose are those who will be directing actions. Those who will be performing the actions will be in the plant at the time of the accident and therefore will not be exposed to the ingress / egress dose.
oc1281-0023a142
Dennis M Crutchfield, Chief 5
Big Rock Point Plant December 18, 1981 Nevertheless, supplemental meteorological capabilities do exist on-site and consist of the Coast Guard, National Weather Service forecasters, and the Mt.
McSauba weather station. These services all provide instantaneous indication of wind speed and direction. Therefore, necessary meteorological information can be obtained directly from these indicators.
As a result of the Emergency Plan Audit just completed at Big Rock Point, Consumers Power Company has agreed to provide additional meteorological data using wind speed 6.d direction indicators located above the containment, with chart readouts Ice ated in the Control Room. This commitment is identified via NRC Region III Confirmation of Action letter dated December 14, 1981. Details of these additional indicators and their operation will be provided in Consumers Power Company correspondence to the Emergency Plan Audit Team.
FINAL RESPONSE TO NUREG-0737 ITEM III.D.3.4:
CONTROL ROOM HABITABILITY REQUIREMENTS The Summary in Part I and the response to NUREG-0737 Item III.A.1.2 in Part II of this letter provides Consumers Power Company's assurance that Control Room operators will be adequately protected against the release of radioactivity and that the plant can be safely operated or shut down under postulated design basis accident conditions.
David P Hoffman Nuclear Licensing Administrator CC Director, Region III, USNRC NRC Resident Inspector-Big Rock Point i
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i CONSUMERS POWER COMPANY Big Rock Point Plant Final Response to NUREG-0737 Items II.B.2, III.A.1.2, III.A.2, and III.D.3.4 Docket No 50-155 License No DPR-6
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At the request of the Commission and pursuant to the Atomic Energy Act of 1954, and the Energy Reorganization Act of 1974, as amended, and the Consnission's Rules and Regulations thereunder, Consumers Power Company submits its final response to NUREG-0737 (NRC letter
" Clarification of TMI Action Plan Requirements" dated October 31, 1981) Items II.B.2, III.A.I.2, III.A.2, and III.D.3.4, dated December 18, 1981.
CONSUMERS POWER COMPANY By O YJ ON LS R B DeWitt, Vice President Nuclear Operations Sworn and subscribed to before me this 18th day of December 1981.
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Helen I Dempski, Notary Public Jackson County, Michigan My commission expires December 14, 1981 4
nu1281-0023bl42
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