ML19345H197
| ML19345H197 | |
| Person / Time | |
|---|---|
| Issue date: | 04/17/1981 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML19345H189 | List: |
| References | |
| FRN-45FR65466, REF-10CFR9.7, RULE-PR-50 NUDOCS 8105010199 | |
| Download: ML19345H197 (7) | |
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O VALUE/ IMPACT STATEMENT FOR INTERIM AMENDMENTS RELATED TO HYDR 0 GEN CONTROL AND CERTAIN DEGRADED CORE CONSIDERATIONS i
1.
PROPOSED ACTION 1.1 Description Section 50.44 of 10 CFR Part 50 is being concidered for amendment to improve hydrogen management in light-water reactor (LWR) facilities and to provide specific design and other requirements to mitigate the consequences of accidents resulting in a degraded reactor core.
The amendments would require inerting of BWR Mark I and II containments, hydrogen control systems for Mark III BWRs and ice condenser PWRs, and would require all LWRs except Mark I and II BWRs to be evaluated with respect to control of significant l
amounts of hydrogen.
Additional amendments would require specific improve-ments in LWR plant design and operations to better respond to and accommodate degraded core accidents.
1.2. Need for Proposed Action The accident at TMI, Unit 2, has necessitated a reexamination of current Commission regulations in connection with the problem of large amounts of hydrogen and releases of radioactive material to the primary coolant system l
that can result following an accident in which the reactor core is severely degraded.
Furthermore, the accident revealed design and operational limita-tions that existed relative to mitigating the consequences of such an accident l
and determining the status of the facility during and following the accident.
1.3 Value/ Impact of Proposed Action 1.3.1 NRC Operations l
NUREG-0660, "NRC Action Plans Developed as a Result of the TMI-2 Accident,"
dated May 1980, itemized the estimated time in man years for NRC resources to complete each task.
The staff effort to complete the tasks needed to implement 810 1
Enclosun T
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s the rule has already been initiated to comply with letters sent to all operat-ing nuclear power plant licensees as well as applicants and construction permit **'
holders (letters from Darrell G. Eisenhut, dated September 13, 1979, September 5, 1980 and October 31, 1980 (NUREG-0737) and letter from Harold R. Denton, dated October 30,1979).
The total estimated NRC manpower to complete the tasks applicable to this rule is 48.2 man years.
Contractor studies to perform detailed technical evaluation for tasks applicable to this rule is estimated to cost $2,420,000.
1.3.2 Other Government Agencies No assistance from other agencies is anticipated.
1.3.3 Industry It is estimated that the implementation of this rule for existing nuclear power reactor licensees, applicants and construction permit holders will involve at least 1400-1600 man years of effort and a capital expenditures of at least 1400 million dollars (1.4 billion).
Additional expenses over the lifetime of i
all plants could result in additional expenditures of up to 560 million dollars (considering inerting costs of 16 Mark I and II plants).
These costs are inferred from NUREG-0660, information supplied by GE to NRC (letter to NRC Chairman Ahearne, dated March 3, 1980), and cost estimates provided by the Atomic Industrial Forum (letter to Harold Denton of NRC, dated February 22, 1980).
As discussed in paragraph I.C.1. of NUREG-0660, most of these costs resulted from the orders sent by the NRC in the letters dated September 13, 1979 and October a, 1979 for operating reactors.
The major additional costs as e, result of this rule alone arise from inerting those Mark I and II BWRs not previously inerted (a total of 16 plants) and from providing hydrogen con-trol systems for Mark III BWRs and ice condenser PWRs (not covered by NUREG-0660).
For the 16 Mark I and II BWRs not previously inerted, the required capital cost is 32 million dollars, and the maintenance cost over the lifetime of these 16 plants is 154 million dollars.
The total maintenance cost of all 36 Mark I and II plants will be 346 million dollars to keep them inerted for the plants' lifetime.
Since there was a high likelihood that the 20 operating Mark I plants now inerted could have been allowed to deinert prior to the TMI-2 accident, it can be inferred that the additional maintenance cost of this rule on inerting is 346 million collars rather than 154 m llion dollars.
2 Enclosure "D"
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Regarding hydrogen control systems for Mark III BWRs and ice condenser PWRs, there are currently 19 Mark IIIs and 7 ice condensers in various stages of the licensing process, and 3 operating ice condensers.
The cost of a dis-tributed igniter system has been estimated to vary from 50 thousand to 100 thousand dollars per plant for materials and labor.
The research and develop-ment associated with this type of system could vary depending upon the prob-lems encountered; about 1 million dollars have been spent and possibly another million could be spent in the future.
Assuming a cost of 100 thousand dollars per plant, the distributed igniter systems would cost about 3 million dollars for the 28 plants for materials and labor and an additional cost of 2 million dollars for R&D.
If a post accident inerting system is used for hydrogen con-trol, the cost could be 8 to 10 million dollars per plant.
If this were used for the 19 Mark III BWRs, it would cost a total of about 170 million dollars.
The final costs would clearly depend upon the type of hydrogen control system selected with the cost being only one of many factors considered in the selec-tion process.
It should be noted that true cost comparisons between the dis-tributed igniter system and inerting systems must also involve costs other than that of the hydrogen control systems themselves.
In particular, the rule requires that systems necessary to ensure safe shutdown and containment integrity must be capable of performing their functions after being exposed to the environmental conditions created by the burning (or local detonation) of hydrogen.
Thus, if a distributed igniter system is used, the costs involved with qualification of these systems for operation during and following an acci-dent with hydrogen burning should be considered.
No good estimates are presently available for determining the magnitude of these costs.
Also required by this rule are design analyses to evaluate measures to mitigate accidents for PWR and Mark III BWR plants for accidents involving large quantities of hydrogen.
No firm estimates are available for these analyses, but they could be in the range of several hundred man years if done l
for each plant individually.
It is anticipated that " owner groups" will be l
formed to analyze " typical" plants and reduce the overall industry costs.
A further cost item resulting from this rule (not included in NUREG-0660) con-cerns the provision for external recombiner capability on those plants that do not now have recombiner capability.
It is estimated that this cost will amount to less than 100,000 dollars per plant and that 40 plants would be affected for a total additional cost of four million dollars.
3 Enclosure "0" t
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1.3.4 Public The impact on public resources could be primarily from increased utility rates for electricity to pay the costs itemized in the previous section.
These interim amendments will result in increased safety for the public.
2.
TECHNICAL APPROACH 2.1 Technical Alternatives The primary technical basis for this rulemaking is NUREG-0578, "TMI-2 Lessons Learned Task Force Status Report and Short-Term Recommendations."
Various alternatives were considered by the Task Force before it made its recommendations.
This report was followed by NUREG-0585, "TMI-2 Lessons Learned Task Force Final Report" dated October 1979 which provided further recommendations.
Based on these documents, a series of letters were sent to operating reactor licensees as well as to applicants for operating licenses and construction permits, and constructions permit holders.
The letters were sent on September 13, 1979, October 30, 1979, September 5, 1980 and October 31, 1980 (NUREG-0737).
These letters were supplemented with regional meetings during the weeks of September 24, 1979 and September 22, 1980 in which members of industry could discuss and comment on various aspects of the recommenda-tions.
The NRC also published in May 1980, NUREG-0660, "TMI-2 Active Plan" which incorporates and expands upon the earlier recommendations.
The fore-going material contains a thorough description of the technical alternatives considered by the Commission in connection with this rulemaking.
2.2 Discussion and Comoarison of Technical Alternatives The Lessons Learned Task Force has prepared a set of specific safety requirements (NUREG-0578) recommended for prompt application in short-term operating reactor licensing activities and in near-term construction permit and operating license reviews.
The decision making process followed by the Task Force was based upon engineering evaluation and qualitative professional judgment of the safety significance of the various issues.
These recommenda-tions were reviewed by the Advisory Committee on Reactor Safeguards (ACRS) and by the Commission.
As a result of the review, the NRC published the TM1 Action 4
Enclosure "D"
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Plan, NUREG-0660, which modified the earlier recommendations and added others.
Furthermore, the NRC has been conducting licensing proceedings relative to new plants with new designs.
This has resulted in the development of additional requirements.
Some of the amendments in this interim rule may eventually be replaced by more comprehensive changes in nuclear power plant regulations as a result of a long-term rulemaking proceeding on degra ded core conditions that has been initiated (45 FR 65474).
The specific recommendations from NUREG-0578 and from NUREG-0660 that are covered by this interim rule are indicated below.
The first designation refers to NUREG-0578 while the second is the corresponding reference in NUREG-0660.
If a designation is left blank it indicates that it was not covered in that particular NUREG.
2.1.3b (II.F.2)
Instrumentation for detection of inadequate core cool-ing for PWRs and BWRs 2.1.5a (II.E.4.1) Dedicated penetrations for external recombiners or post-accident external purge systems 2.1.5b (
)
Inerting BWR containments (Mark I and Mark II BWRs) 2.1.5c (
) External recombiner capability 2.1.6a (III.D.1.1)
Integrity of systems outside containment likely to contain radioactive materials (II.B.1) Reactor coolant system vents 2.1.6b (II.B.2) Design review of plant shielding of spaces for post-accident operations 2.1.8a (II.B.3)
Improved post-accident sampling capability (II.B.4) Training for mitigating core damage 5
Enclosure "D"
e (II.B.7) Design analysis for hydrogen control 2.1.8b (II.F.1)
Increased range of radiation monitors 2.1.8c (III.D.3.3)
Improved in plant iodine instrumentation Additional items covered by the interim rule that were not covered previously, but which surfaced as a result of regulatory proceedings are:
1.
Hydrogen control systems for large amounts of hydrogen for Mark III BWRs and ice condenser PWRs.
2.
Survivability of safety systems during and following a hydrogen burn for BWRs and PWRs where burning can occur.
2.3 Decision on Technical Approach The Commission's decisions on the technical alternatives can be found in the documents described in the two previous sections.
3.
PROCEDURAL APPROACH Because of the significance of the TMI-2 incident, interim rulemaking actions were recommended by the Lessons Learned Task Force, followed by a more systematic change in nuclear power plant regulations.
A proposed interim rule was issued on October 2, 1980 with opportunity for public comment.
This resulted in 35 comment letters with over 160 separate comments.
Based on the comments received, the various regional meetings and responses to Commission correspondence (see 1.3.3), and recent regulatory proceedings, the NRC staff revised the interim rule.
Furthermore, various segmeats of the industry were contacted to determine the rule's impact, including ooth cost and technical aspects, on their facilities.
It should be noted that a number of the requirements of the interim rule are already being implemented by licensees and construction permit holders as a result of recommendations that were made in the previously discussed letters and NUREG reports.
6 Enclosure "D"
o 4.
STATUTORY CONSIDERATIONS The Commission's authority for the actions discussed is based on Sec-tions 103 and 161 of the Atomic Energy Act of 1954, as amended.
5.
RELATIONSHIP TO OTHER EXISTING OR PROPOSED REGULATIONS OR POLICIES See previous discussion at 1.3.
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Enclosure "D"
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