ML19329F425
| ML19329F425 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 06/18/1970 |
| From: | Hendrie J Advisory Committee on Reactor Safeguards |
| To: | Seaborg G US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML19329F421 | List: |
| References | |
| NUDOCS 8006270468 | |
| Download: ML19329F425 (6) | |
Text
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e ADVISORY COMMITTEE ON REACTOR SAFEGUARDS UNITED STATES ATOMIC ENERGY COMMISSION WASHINGTON D.C. 20545 June 18, 1970 Honorable Glenn T. Seaborg Chairman U. S. Atomic Energy Commission Washington, D. C.
20545
Subject:
REPORT ON MIDLAND PLANT UNITS 1 & 2
Dear Dr. Seaborg:
During its 122nd meeting, June 11-13, 1970, the Advisory Committee on Reactor Safeguards completed its review of the application by the Consumers Power Company for a permit to construct th.s Midland Plant Unfts 1 and 2.
During this review, the project also was considered at Subcommittee meetings held on January 22, 1969, at the plant site, on April 24, 1970, at Chicago, Illinois, on February 4 1969, March 24, 1970, and June 10, 1970, at 5
Washington, D. C and at the ACRS meetings of February.6,1969, April 9, and May 8, 1970, in Washington, D. C.
In the course of these meetings, the Committee had the benefit of discussions with representatives and consultants of the Consumers Power Company, Babcock and Wilcox Company, Bechtel Corporation, Dow Chemical Company, and the AEC Regulatory Staff. The Committee also had the benefit of the documents listed.
The Midland Plant site is on the south bank of the Tittabawassee River adjacent to the southern city limits of Midland, Michigan. The main industrial complex of the Dow Chemical Company lies within the city limits directly across the river-from the site and provides en area of controlled necess about two miles wide between the reactor site and the Midland busi-ness and residential districts. The exclusion area of the plant site has a radius of 0.31 miles and includes a small segment of the Dow plant; no Dow employees are permanently assigned in this segment, and the applicant hes the right to remove any persons from this segment if conditions warrant.
The low population zone has a' radius of 1.0 miles and contains 38 permanent tesidents and about 2,000 industrial workers, mainly employees of Dow Chemical Company. The number of permanent residents within five miles of the plant site was estimated to be 41,000 in 1968, mainly in the city of a
Midland and its environs..
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. Honorable Glenn T. Seaborg June 18, 1970
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The applicant'has established criteria for, and has begun the formulation.
of a comprehensive emergency evacuation plan. This plan is being coordinated with.the well-established plan of the Dow Chemical Company for emergency evacuation of the Midland chemical plant and portions of the City of Midland in case of major emergencies at the chemical plant. Close coordination with appropriate municipal and state authorities is also being established.
The Midland units will each include a two-loop pressurized water reactor designed for initial core power levels up to 2452 MWt. The nuclear steam
. supply systems and ' the emergency core cooling systems of these units are essentially identical with those for the previously reviewed Oconee Units 1, 2 and 3 and Rancho Seco Unit 1 (ACRS reports of July 11, 1967 and July.19, 1968, respectively). The, combined electrical output of the two units will f
be 1300 MW.'
In addition, 4,050,000 lbs per hour of secondary steam will be exported to the adjacent Dow plant to supply thermal energy for chemical 4
processing operations.
The prestressed, post-tensioned concrete reactor containment buildings are similar to those approved for the Oconee Units 1, 2 and 3.
The design will i
include penetrations, which can be pressurized, and isolation valve seal water systems to reduce leakage. Channels will be welded over the seam welds of. the containment liner plates to permit leak testing of the seam welds.
Cooling water for the Midland reactors is supplied from a diked pond with a capacity of 12,600 acre-feet. Make-up water is taken from the Tittabawassee
' River. The cooling water supply is sufficient for 100 days of full power operation without make-up during periods of low river flow. In the unlikely event of a gross leak through the dikes of the cooling pond, a supplemental source of water will be available. The supplemental source is provided within the main pond by excavating a 24 acre area to a depth of six feet below the bottom of the main pond. This source can supply shut-down cooling capability for 30 days without make-up.
The applicant will conduct an on-site meteorological monitoring program to verify the applicability of the meteorclogical models used for accident i
evaluation and routine. release limits as well as to determine any meteoro-logical effect of the cooling pond..This program should be completed during construction.
. Midland is the first dual purpose reactor' plant to be licensed for construc-i
. tion. The export steam originates from the secondary side of the steam l.
generators and may contain traces of radioactive leakage from the primary system..The' demineralized condensate from 60 to 75 percent of the export steam is returned by Dow to the. feed water supply of the reactor-plant.
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The condensate from the remaining steam is either chemically contaminated or cannot practically be returned to the nuclear plant. It is collected in
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L thelDow waste treatment system for dilution and processing with other streams '
-before eventual discharge to the river. Thus, the unreturned portion of the condensate represents an effluent from the reactor-plant to which the require-L ments of 10 CFR Part 201must ' apply.
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s Honorable Glenn T. Seaborg June 18, 1970 This matter may be considered in two parts:
(1) the steps taken by the applicant"to ensure that any radioactivity in the export steam is within the limits set by 10 CFR Part 20 and as low as practicable and (2) the measures taken by the Dow Chemical Company to ensure that the export steam can be used in chemical operations without product contamination and that the unreturned steam condensate is properly managed for safe disposal.
In connection with item (1), the applicant proposes to monitor and control radioactivity in the export steam. A representative, continuous sample of the export steam will be condensed for monitoring and laboratory analysis.
The gamma activity of this flowing sample will be continuously monitored by on-line analyzers and an alarm actuated if the activity exceeds an appropriate limiting value. The alarm will serve to indicate any change in the integrity of the steam generators or fuel cladding. Samples of this condensate stream will be analyzed at appropriate intervals by sensitive low-level boca counting for determination of gross beta activity and concentration of selected radionuclides. The applicant agrees to limit, by maintaining high integrity of the steam generators and fuel cladding, the yearly average gross beta activity in the export steam to one-tenth or less of the limits specified by 10 CFR Part 20 for the selected radionuclides.
The yearly average will include any periods of short duration when the concentrations may approach but not exceed the 10 CFR Part 20 limits. The applicant states that in his judgement it is practical to operate the plant within these limits. If these limits are exceeded, corrective measures will be taken in the plant or the delivery of export steam to Dow will be terminated. He also agrees to demonstrate the analytical equipment and procedures in development programs to be carried forward and completed during construction of the Midland Plant. In connection with item (2),
Dow has stated that they will apply for a 10 CFR Part 30 Materials License to receive, possess,and use the export (secondary) steam as a source of thermal and mechanical energy. No export steam or condensate will be intentionally introduced into any product. Isolation of the export steam from contact with products will be accomplished by the use of heat exchange devices which will provide suitable physical barriers. Programs will be established to provide for detection of Icaks in the heat exchange devices by analyses, monitors, and other means; for repair of leaks when detected; and for* appropriate administrative control of the programs.
Dow has stated that accumulation of radioactivity from the export steam and release of radioactive materials in the effluent will be in accordance with 10 CFR Part 20. The unreturned condensate will represent less than 10% of the total liquid effluent disposed of through the Dow waste treat-ment plant and the annual average concentration in the total effluent is expected to be les_s than 1% of the 10 CFR Part 20 limits.
The Committee believes that the criteria proposed by the applicant and Dow for the control of radioactivity in the export steam are necessary
__and adequate. _The1 detailed procedures for implementation should be developed during cor.struction in a manner' satisfactory to th'c Regulatory
- Staff, The Committee wishes to be kept informed.
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m Honorable Glenn T. Seaborg June 18, 1970 To minimize the likelihood of subsidence at the site, the applicant and Dow have agreed to prohibit future salt mining operations within one-half mile from the center of the reactor plant. No new wells will be drilled within this distance and all existing wells will be abandoned and plugged.
The Committee believes these arrangements are satisfactory.
2 A large voluma of liquid chlorine is maintained in a refrigerated storage vessel about one mile from the Midland plant control room. The applicant is continuing his study of the consequences of a major accidental release of chlorine from this vessel. He has included in his criteria for the design of the. control room the objective of finding.a practical method of maintaining the concentration of chlorine in the control room atmosphere below the eight hour threshold limiting value (TLV) of 1 ppm for the most serious conceivable chlorine accident. The Committee believes that adequate air purification facilities should be provided in the control room ventilation system to reduce chlorine concentration to the eight hour TLV of 1 ppm so that operators can work without respiratory equipment during an extended chlorine emergency. This matter should be resolved i
during construction in a manner satisfa: tory to the Regulatory Staff.
The reactor vessel cavity will be designed to withstand mechanical forces l
.and pressure transients comparable to those considered in the design of the Zion and Indian Point-3 plants.
The applicant has stated that he will provide additional evidence obtained
.__._ ___, by improved multi-noda analytical techniques to assure that the emergency core coaling system is capable of limiting core temperacures to the limits 3
. estab1f.shed at present. He will also make appropriate plant changes if
. the further analysis demonstrates that such changes are required. This matter should be resolved'during construction in a manner satisfactory to the Regulatory Staff. The Committee wishes to be kept informed.
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The safety injection system for the Midland plant is actuated by either low reactor pressure or high containment pressure signals. However, of
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these two,the. reactor is tripped only by the low reactor pressure signal.
The Committee believes that provision also should be made to trip the i
reactor by the high containment pressure signal.
The applicant plans to develop more detal' led criteria for the installation of protection and emergency. power systens together with appropriate procedures to maintain the physical and electrical ir. dependence of the redundant portions of these systems. The Committee believes that these 4
.. __ criteria and procedures should be reviewed and approved by the Staff prior to actual installation.
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' Honorable Glenn T. Seaborg 5-June 18, 1970 The applicant considers the possibility of. melting and subsequent disintegration of a portion of a fuel assembly because of flow starvation, gross enrichment error, or from other causes to be remote. However, the
. resulting effects in terms of local high temperature or pressure and possible initiation of failure in adjacent fuel elements are not well known. Appropriate studies should be made to show that such an incident will not lead to unacceptable conditions.
The Committee believes that consideration should be given to the utili-
- zation of. instrumentation for prompt detection of gross failure of a fuel element.
The Committee.has commented in previous reports on the development of systems to control the buildup of hydrogen in the containment which might follow in the unlikely event of a major accident. The applicant i
proposes to make use of a technique of purging through filters after a suitable time delay subsequent to the accident. However, the Committee recommends that the primary protection in this regard should utilize a hydrogen control method which keeps the hydrogen concentration within safe limits by means other than purging. The capability for purging should also be provided. The hydrogen control system and provisions for containment atmosphere mixing and sampling should have redundancy and instrumentation suitable for an engineered safety feature. The Committee wishes to be kept informed of the resolution of this matter.
1 The Committee recommends that the applicant accelerate the study of means of preventing common failure modes from negating scram action and of design features to make tolerable the consequences of failure to scram during anticipated transients. The applicant stated that the engineering design would maintain flexibility with regard to relief capacity of the primary system and to a diverse means of reducing reactivity. This matter should be resolved in a manner satisfactory to the Regulatory Staff during construction. The Commitcee wishes to be kept informed.
Other problems related to large water reactors have been identified by' the Regulatory Staff and the ACRS and cited in previous ACRS reports.
The Committee believes that resolution of these items should apply equally toLthe Midland Plant Units 1 & 2.
- The Committee' believes that the above items can be' resolved during con-
- struction and that, if due consideration is given to these items, the e
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Honorable Glenn T. Seaborg June 18, 1970 nuclear units propoced for the liidland Plant can be coactructed tiith reasonable assurance that they can be operated seithout undue risk to the health and safety of the public.
Sincerely yours, OriSinal Signed by Joseph M. Hendrio Joseph !!. Hendric Chairman References
- 1) Amendmento 1 - 12 to Licence Application e
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