ML19257C306
| ML19257C306 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/17/1980 |
| From: | Doug Garner, Norian P, Rubin M, Wilson B NRC - TMI-2 BULLETINS & ORDERS TASK FORCE, Office of Nuclear Reactor Regulation |
| To: | CALIFORNIA, STATE OF |
| Shared Package | |
| ML19257C304 | List: |
| References | |
| NUDOCS 8001250578 | |
| Download: ML19257C306 (17) | |
Text
01/17/80 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LI_ CENSING BOARD In the Mteter of
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SACRAMENTO MUNICIPAL UTILITY DISTRICT
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Docket No. 50-312 (SP)
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(Rancho Seco Nuclear Generating Station))
NRC STAFF'S RES?0NSES TO CALIFORNIA ENERGY COMMISSION"S SECOND SET OF INTERROGATORIES TO THE NUCLEAR REGULATORY COMMISSION CEC Interrogatorv 1 Provide NRC's evaluation concerning the acceptability of increased reactor trips and the initiation of auxiliary feedwater in connectiin with feedwater transients.
Resoonse:
Plant events such as reactor trips and auxiliary feedwater initiation are of interest because they subject the reactor coolant system to various levels of thermal stress. During the course of the Rancho Seco design, certain criteria were established for allowable plant transients which would result in thermal cycles on the coolant system.
These criteria are detailed in a B6k' design report, serial # CS(F3-92).
The report describes how many transients of each category are allowed for in the basic plant design.
An increased number of reactor trips and auxiliary feedwater initiation is of no safety concern to the Staff, as long as the design criteria in the above reference are not exceeded.
At the present, none of the transient limits are anywhere near being reached.
During the course of plant operation, all eeents and operating conditions are monitored and recorded to assure an accurate is being maintained regarding the thermal cycles which Rancho Sc'o account has been subjected to.
08 087 8001250 f
_2 If at some time in the future, the applicant believes that the limits for thermal cycles resulting in reactor trips or auxiliary feedwater will be exceeded, it is required to notify the Staff.
The Staff will then review the applicant's submittal and determine what additional analysis or plant modifications are required before new transie-limits are established.
CEC Interrocatorv 2 Explain any sensitivities of B&W reactor systems that may require use of HPI in conjunction with feedwater transients.
Response
The NRC has recently required a number of plants similar to Rancho Seco to perform studies of feedwater type transients.
The study results showed that for a severe overcooling feedwater transient, the primary system pressure would decrease to the HPI initiation setpoint.
While this action occurs automatically, HPI flow is not required to prevent core uncovery, since no primary system inventory is actually lost during a feedwater transient.
CEC Interrogatory 3 B&W reactor systems appear to be unusually sensitive to feedwater transients, particularly because of the once-through steam generator, coupled with the pressurizer sizing. ICS design and PORV/ reactor trip set points.
What design and equipment changes would eliminate this sensitivity? Are such changes planned? When?
Response
The Staff is currently considering the issue of sensitivity in B&W reactors and has recently requested that constructors of plants similar to Rancho Seco conduct studies to determine ways the sensitivity could be reduced.
While this information was requested, it was not felt that B&W system sensi-1808 088
. tivity posed an actual safety hazard which had to be dealt uith on operating plants. Rather, it was done in an attempt to determine how plants currently under construction could generally be improved.
The Staff does not currently believe that the present system response of Rancho Seco is unacceptable from a safety perspective, though it is acknowledged that there are some areas where system response could be dampened.
As part of the Staff's effort to evaluate the sensitivity analyses submitted by B6W construction permit holders, we will continue to consider whether actual safety problems do result from the sensitivity.
If additional analyses and study indicate a safety-problem due to the B&W plant sensitivity, changes will be required on Rancho Seco.
While changes have not been finalized, they would likely follow suggestions made by present B&W construction permit holders.
These suggestions are numerous, but some of the more significant ones are outlined below:
MODIFICATIONS WITH POTENTIAL TO REDUCE PLANT SENSITIVITY TO CHANGES IN FEEDWATER SUPPLY I.
MAIN FEEDWATER (MFW) SYSTEM A.
SEPARATE SYSTEM TO LIMIT MFW ADDITION RESULTING FROM CONTROL SYSTEM FAILURE.
B.
SYSTEM TO PROTECT AGAINST MFW OVERFILL AFTER REACTOR TRIP / TURBINE TRIP.
C.
ANTICIPATORY TRIP FOR LOSS OF MFW, 1808 089 II.
AUXILIARY FEEDWATER (AFW) SYSTEM A.
MODIFICATIONS TO LIMIT C00LDOWN FOLLOWING AFF INITIATION BY FLOW CONTROL AND/0R MULTIPLE SETPOINTS FOR FINAL LEVEL.
B.
AFW DIRECTED INTO LOWER PORTION OF STEAM GENERATOR.
C.
IMPROVED ALGORITHM FOR AFW PLANT C0tlTROL, D.
AFW FEED ONLY GOOD GENERATOR (F0GG' Other than an anticipatory reactor trip for loss of main feedwater, there are no current plans to include the above modifications in Rancho Seco's systems.
Rancho Seco presently has a control grade anticipatory trip system, which will soon be upgraded to safety quality.
CEC Interrocatorv 4 k'ha t prevented the use of the low pressure injection system at TMI?
Respons(:
The low pressure injection system is designed to mitigate the consequences of a large rupture in the reactor coolant system.
The accident which took place at TMI-2 involved the sticking open of a power operated relief valve, which is equivalent to a small rupture of the reactor coolant system.
Consequently the rate of fluid loss at n!I was relatively small and the system pressure remained above the point at which the low pressure injection system could operate.
The high pressure injection is designed to operate in the event of accidents such as occurred at D1I-2 and was so used.
1808 090 CEC Interrogatory 5 At page 6 of SMUD's responses (Set 3) to CEC's First Set of Interrogatories, SMUD states that "for anticipated loss of feedwater transients, void forma-tion does not occur in the B&W Nuclear Steam System." Does the NRC Staff agree? Explain.
Response
The Staff cannot respond with an unqualified yes or no to this interrogatory.
The Staff believes that bulk void formation will not cccur for anticipated loss of feedwater transients.
This results primarily from the addition of the anticipatory reactor trip on loss of feedwater which quickly scrams the reactor for this event. Thus, the bulk coolant temperatures are reduced and remain subcooled even though the reactor coolant system may decrease in pressure by approximately 600 psi.
At a pressure of 1600 psi, the corresponding satura-tion temperature is about 605"F.
The expected core exit temperature at this time would be approximately 550*F (assumes the transient was initiated from full power).
It is possible, however, to postulate some local boiling following a loss of feedwater.
Fluid from the core exit is normally mixed in the upper plenum and transported via the hot legs to the steam generators.
If fluid from the exit of the hottest fuel assemblies (about 630*F) should hide out and not mix well with the bulk coolant, local void formation could occur during reactor coolant system depressurization. The hotter fluid would eventually mix with the bulk fluid and be condensed.
It is expected that the formation of local voids in the upper plenum would have no significant effect on plant performance.
18108 091 CEC Interrogatorv 6 Identify any event involving HPI operation that could result in RCS void formation in B&W reactor systems.
P:sponse:
Void formation would occur in the reactor coolant system following a postulated Ioss of coolant accident including a stuck open pressurizer power operated relief valve.
For these events, the HPI system would be initiated.
The HPI system could also be initiated following loss of feedwater or postulated overcooling transients.
Potential void formation following loss of feedwater transients is discussed in response to Interrogatory #5 (CEC-Second Set).
An overcooling of the reactor coolant system could occur if the reactor were scrammed and the feedwater system inadvertently maintained the nominal full power flow rate.
The resulting primary system depressurization would result in some void formation in the reactor coolant system.
CEC Interrogatory 7 In response to CEC Interrogatory #5, the NRC stated that natural circulation can be maintained in lowered loop plants provided " sufficient inventory exists to raise the liquid level in the steam generators above that of the bottom of the pump discharge nozzle." Explain the heat removal mechanisms required to cool the fuel rod bundles and how heat is removed in the steam generator.
Response
The Staff response to CEC Interrogatory #5 (First Set) relates to the minimum primary system liquid inventory required to maintain natural circulation.
Under this condition, sufficient fluid would exist in the steam generators to clear the loop seal, and the reactor core would be covered or nearly covered.
The fuel rod bundles will be cooled by boiling the liquid in the core, and the 1808 092
. resulting steam will be condensed in the steam generators by the auxiliary feed-This mode of cooling is defined as " natural condensation cooling" in water.
CEC's Request for Admissions to the hRC.
CEC Interrogatory 8 In response to CEC Interrogatory 15, the NRC Staff states that the " nature" of the oral audits of Rancho Seco licensed personnel is set forth in the Staff's June 27, 1979 " Evaluation of Licensee's Compliance with the NRC Order Dated May 7, 1979." However, in the Evaluation, the audits are merely mentioned but not described in detar.
Please describe each such audit in detail. Also describe any other audir.s performed since June 1979.
Response
The initial audits of the Rancho Seco licensed personnel following the TMI-2 accident were conducted on June 1 and 2, 1979 by an Operator Licensing Branch Examiner (B. Wilson) and an I&E Inspector (P. Johnson).
Seven operators and senior operators were verbally quizzed for approximately one to one and one-half hours each.
The subjects covered were the TMI-2 sequence of events, the small break loss of coolant accident (LOCA) phenomenon, the Rancho Seco revised LOCA procedure, and design and procedure changes made at Rancho Seco as a result of the May 7, 1979 Order.
Mr. Johnson conducted eight additional audits, five of which were re-audits, during the week of June 11, 1979 covering the same topics as above.
CEC Interrocatory 9 What programs or investigations have been conducted by NRC to verify and demon-strate that operational crews have adequate diagnostic capability to identify and resolve multiple failure accident events? What is the basis for demonstrating acceptable diagnostic skills to the NRC? What grading standards are used in written and/or oral examinations to assure that operator skills are a e uate
Response
All programs and investigations that relate to the training, qualification, and evaluation of licensed operators and senior operators were identified in the NRC response to Interrogatory 13 of the California Energy Commission's First Set of Interrogatories. The basis for demonstrating acceptable diagnostic skills to the NRC and the grading standards are contained in the documents referenced in the response or will be included when the studies are completed.
CEC Interrogatory 10 Describe current NRC programs for maintaining (on a long-term basis) the quality control of written operational procecures (especially for emergency conditions) at the Rancho Seco facility. What efforts will be taken on a long-term basis to assure that significant experience ir. other nuclear facilities are assimilated by Rancho Seco personnel and incorporated into formally prepared procedures?
Response
The current NRC program for assuring quality control of written operating pro-cedures is carried out by the Of fice of Inspection and Enforcement (I&E) in a formal inspection program. This inspection program is described in I&E Manual Chapter 2500.
The I&E program contains provisions for assuring that required procedures exist at the facility, that procedure format and content is such that the procedures can be followed to fulfill their intended functions, and that changes to procedures undergo the proper review process (including quality assurance) required by the Rancho Seco Technical Specifications.
The long-term efft,rts to be taken to ensure feedback of operating experience at other facilities include actions by both the NRC and the nuclear industry.
The efforts that will be taken are summarized as Task I.E of LUREG-0660 (DRAFT) of December 10, 1979.
The Task Force objective is to establish an integrated program, which involves participation by licensees, NSSS vendors, Nuclear Safety Analysis Center (NSAC), Institute of Nuclear Power Operations (INPO), and the NRC and includes foreign experience, for the systematic collection, review, analysis, and feedback of operating experience to all NRC-licensed activities.
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CEC Interrogatory 11 Describe current NRC programs for maintaining efforts to evaluate the quality control of continuing training programs for operators and management personnel at Rancho Seco.
What efforts will be taken on a long-term basis to assure that significant experiencos in other nuclear facilities are incorporated into the training program at Rancho Seco?
Response
" Continuing Training Programs" would be handled as part of the Requalification Program for licensed operators and senior operators.
Appendix A to 10 CFR Part 55 specifies the regulatory requirements for the Requalification Program.
The NRC Staff evaluates the " quality control" of the Requalification Program by the means described below.
- 1) The programs are submitted to the NRC's Operator Licensing Branch (OLB) for review and approval.
- 2) The NRC's Office of Inspec-tion and Enforcement (I&E) is responsible for verifying that the programs have been implemented and are being conducted in accordance with the program descrip-tion as approved by OLB.
- 3) I6E is also responsible for determining whether sufficient dorumentation is being maintained by the licensee to permit OLB examiners to verify the technical adequacy of licensee administered examinations.
- 4) OLB examiners are responsible for reviewing the contents of the written examinations taken by the licenso' operators and management's evaluation of the operator's performance.
The efforts that will be taken on a long term basis to assure that significant experiences in other nuclear facilities are incorporated into the training pro-gram at Rancho Seco are the following:
1.
The NRC has established an agency-wide Office of Operational Data Analysis and Evaluation and has directed the individual program offices to establish operational data analysis capability.
1808 09e3 2.
The Electric Power Research Institute (EPRI) has founded a Nuclear Safety Analysis Center (NSAC) to systematically review available plant event reports and data.
3.
The nuclear utility industry has established the Institute for Nuclear Power Operations (INPG), one of whose tasks is to review nuclear power operating experiences for analysis and feedback to the utilities.
4.
Revisions are expected to be made to Appendix A of 10 CFR Part 55 that will require input from these operational analysis organi-zations to be factored into the Requalification Programs.
CEC Interrogatory 12 If the NRC Staff denies in whole or in part any of the requested admissions filed by CEC to NRC Staff, dated December 21, 1979, provide the basis for each such denial.
Response
The basis for each such denial is provided in the NRC Staff's response to the requested admissions dated January 17, 1980, 1808 096
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD, In the Matter of
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SACRAMENTO MUNICIPAL UTILITY DISTRICT
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Docket No. 50-312 (SP)
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(Rancho Seco Nuclear Generating Station))
AFFIDAVIT OF PAUL E. NORIAN Paul E. horian deposes and says under oath as follows:
1.
I was the Alternate Group Leader of the Analysis Group, Bulletins and Orders Task Force.
I coordinated the reviews of small break loss-of-coolant accidents (LOCA) and transient analyses submitted by vendor owner's groups since the Three Mile Island Accident. My professional qualifications are attached to the NRC Staff response to California Energy Commission's First Set Interrogatories 5 and 7 filed in this proceeding.
2.
The answers to the California Energy Commission's Second Set Interroga-tories 5, 6 and 7 were prepared by me.
I hereby certify that the answers given by me are true and accurate to the best of my knowledge.
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Paul E. Norian Subscribed and sworn to before me this 17th day of January, 1980 i
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Notary Public My Commisssion Expires:
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..4 1808 097
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of
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SACRAMENTO MUNICIPAL UTILITY DISTRICT
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Docket No. 50-312 (SP)
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(Rancho Seco Nuclear Generating Station))
AFFIDAVIT OF BRUCE A. WILSON Bruce A. Wilson deposes and says under oath as follows:
1.
I am a tractor engineer in the Nuclear Regulatory Commission Staff's Operator Licensing Branch.
I am responsible for the preparation and administration of written, oral, and practical exams for operators' and senior operators' licenses at production and utilization facilities.
Since Fby,1979, I have been assigned to the Systems Group, Bulletins and Orders Task Force. My professional qualifications are attached to the NRC Staff response to California Energy Commission's First Set Interrogatory 17 filed in this proceeding.
2.
The answers to the California Energy Commission's Second Set Interroga-tories 8, 9 and 11 were prepared by me.
I hereby certify that the answers given by me are true and accurate to the best of my knowledge.
M 44
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Bruc/ A. Wilson Substribed and sworn to before me this(1TJfday of January. 1980
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of
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SACRAMENTO MUNICIPAL UTILITY DISTRICT
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Docket No. 50-312 (SP)
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(Rancho Seco Nuclear Generating Station))
AFFIDAVIT OF DANIEL J. GARNER Daniel J. Garner deposes and says under oath as follows:
1.
I am a Project Manager in the Nuclear Regulatory Commission Staff's Operating Reactors Branch 4.
I am responsible for the overall coordi-nation of licensing actions as they apply to the operating license of the Rancho Seco Nuclear Generating Station.
My professional qualifica-tions are attached to the NRC Staff response to California Energy Commission's First Set Interrogatory 17 filed in this proceeding.
2.
The answer to the California Energy Commission's Second Set of Interroga-tory 10 was prepared by me.
I hereby certify that the answer given is true and accurate to the best of my knowledge.
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L'lhL Daniel J. Da ner Subscribed and sworn to before me this 17th day of January, 1980
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1808 099
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the :iatter of
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SACRAMENTO MUNICIPAL UTILITY DISTRICT
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Docket No. 50-312 (SP)
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(Rancho Seco Nuclear Generating Station))
AFFIDAVIT OF MARK P. RUBIN Mark P. subin deposes and states under oath as follows:
1.
I am s Reactor Engineer, Reactor Systems Branch, Division of Systems Safety, U.S. Nuclear Regulatory Commission.
I am responsible for evaluating the capability of reactor systems needed for safe shutdown during normal and accident conditions, including the performance of emergency core cooling systems.
In addition, I was on temporary detail to the Bulletins and Orders Task Force where I was involved in the evalua-tion of operating reactor responses to the bulletins issued following the accident at TMI.
2.
The answers to the California Energy Commission's Second Set of Interroga-tories 1, 2, 3 and 4 were prepared by me.
I certify that the answers given by me are true and accurate to the best of my knowledge.
,/
GL Lw Mark P. Rubin Subscribed and sworn to before me thie /77dday of.Tanuary,1980 f
Notary Public MyCommiseionExpires:#b3' /j /771 7
1808 100
1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of
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SACRAMENTO MUNICIPAL UTILITY DISTRICT
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Docket No. 50-312 (SP)
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(Rancho Seco Nuclear Generating Station))
NOTICE OF APPEARANCE Notice is hereby gicen that the undersigned attorney herewith enters an appearance in the captioned matter.
In accordance with 8 2.713(a),10 CFR Part 2, the following information is provided:
Name Richard L. Black Address U.S. Nuclear Regulatory Commission Office of the Executive Legal Director Wa sh ir.gt on, D. C.
20555 Telephone Number Area Code 301 - 492-7417 Admissions United States Court of Appeals for the District of Columbia Supreme Court of Florida Name of Party NRC Staff U.S. Nuclear Regulatory Commission Washington, D. C.
20555
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Richard L. Black Counsel for NRC Staff Dated at Bethesda, Maryland this 17th day of January, 1980 1808 101
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of
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SACRAMENTO MUNICIPAL UTILITY DISTRICT
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Docket No. 50-312 (SP)
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(Rancho Seco Nuclear Generating Station))
CERTIFICATE OF SERVICE 1 hereby certify that copies of "NRC STAFF'S RESPONSE TO CALIFORNIA ENERGY COMMISSION'S SECOND REQUEST FOR PRODUCTION OF DOCUMENTS TO THE NUCLEAR REGULA-TORY COMMISSION" and "NRC STAFF'S RESPONSES TO CALIFORNIA ENERGY COMMISSION'S SECOND SET OF INTERROGATORIES TO THE NUCLEAR REGULATORY COMMISSION" and " NOTICE OF APPEARANCE" for Richard L. Black in the above-captioned proceeding have been served on the following by deposit in the United States mail, first class, or, as indicated by an asterisk, through deposit in the Nuclear Regulatory Commis-sion's internal mail system, this 17th day of January, 1980:
Elizabeth S. Bowers, Esq., Chairman
- Gary Hursh, Esq.
Atomic Safety and Licensing Board 520 Capitol Mall U.S. Nuclear Regulatory Commission Suite 700 Washington, DC 20555 Sacramento, CA 95814 Dr. Richard F. Cole
- Mr. Richard D. Castro Atomic Safety and Licensing Board 2231 K Street U.S. Nuclear Regulatory Commission Sacramento, CA 95816 Washington, DC 20555 James S. Reed, Esq.
Mr. Fredrick J. Shon*
Michael H. Remy, Esq.
Atomic Safety and Licensing Board Reed, Samuel & Remy U.S. Nuclear Regulatory Commission 717 K Street, Suite 405 Washington, E.
20555 Sacramento, CA 95814 David S. Kaplan, Esq.
Christopher Ellison, Esq.
General Counsel Dian Grueneich, Esq.
Sacramento Municipal Utility District California Energy Commission P. O. Box 15830 1111 Howe Avenue Sacramento, CA 95813 Sacramento, CA 95825 Herbert H. Brown, Esq.
Mr. Michael R. Eaton Lawrence Coe Lanpher, Esq.
Energy Issues Coordinator Hill, Christopher and Phillips, P.C.
Sierra Club Legislative Office 1900 M Street, N.W.
1107 9 Street, Room 1020 Washington, DC 20036 Sacramento, CA 95814
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Thomas A. Baxter, Esq.
Atomic Safety and Licensing Shaw, Pite an, Potts & Trowbridge Appeal Panel (5)*
1800 M Street, N.W.
U.S. Nuclear Regulatory Commission Washington, DC 20036 Washington, DC 20555 Atomic Safety and Licensing Docketing and Service Section (7)*
Board Panel
- Office of the Secretary U.S. Nuclear Regualtory Commission U.S. Nuclear Regulatory Commission Washington, DC 20555 Washington, DC 20555
./Oj,v l ^*' p a d Richard L. Black Counsel for NRC Staff 1808 103