ML20011F649
| ML20011F649 | |
| Person / Time | |
|---|---|
| Issue date: | 02/26/1990 |
| From: | Beckjord E NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Morris B NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| REF-GTECI-140, REF-GTECI-NI, TASK-140, TASK-OR NUDOCS 9003070081 | |
| Download: ML20011F649 (4) | |
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UNITED STATES i
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HEMORANDUM FOR:
Bill H.' Morris, Director Division of Regulatory Applications, Office of Nuclear Regulatory Research FROM:
Eric S. Beckjord, Director, Office of Nuclear Regulatory Research
SUBJECT:
GENERIC ISSUE.140, " FISSION PRODUCT REMOVAL SYSTEMS" The prioritization of Generic Issae 140, " Fission Product Removal Systems,"
shows that the safety concerns have been addressed in the Severe Accident t
Program with changes to the Standard Review Plan. Therefore, this issue will be DROPPED frefa further consideration.
The enclosed prioritization evaluation will be incorporated into NUREG-0933, "A Prioritization of Generic Safety Issues," and is being sent-to the regions, other offices, the ACRS, and the PDR, by copy of this memorandum and its enclosure, to allow others the opportunity to coment on the evaluation. All coments should be sent to the Advanced Reactors and Generic Issues Branch, DRA, RES (Mail Stop NL/S-169).
Should you have.any ouestions pertainin the contents of this memorandum, please contact Ronald Emrit (492-3731)g to f'
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/ # Eric S. Beckjord, Director Office of Nuclear Regul? tory Rescerch
Enclosure:
Prioritization Evaluation cc:
T. liurley, NRP,'
E. Jordan, AEOD W. Russell, Reg. I S. Ebneter, Reg. II A. Davis, Reg. III R. Martin, Reg. IV J. Martin, Reg. Y (PDR%
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i ENCLOSURE PRIORITIZATION EVALUATION Generic Issue 140:
Fission Product Removal Systems
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ISSUE 140:
FISSION PRODUCT REMOVAL SYSTEMS DESCRIPTION The issue, as originally proposed.1:e addressed the concern for fist. ion product removal by the containment sprays and suppreFsion pools in PWRs and BWRs, respectively; however, it was expanded to include PWR plants that use ice condenser systems for fission product cleanup.
Thus, the original title of the issue, " Fission Product Removal by Containment Sprays or Pools." was c ortened to be consistent with the addition of the ice condenser systems as part of the issue resolution.
Specifically the issue called for SRP11 changes to:
(1) eliminate overly conservative assumptions in estimating the effectiveness of post-accident fission product removal by containment spray systems; (2) specify the pH range for recirculating solutions; and (3) resolve an inconsistency in regulatory guidance by giving credit to pressure.
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suppression pools as post-accident fission product cleanup systems in BWRs.
Although considered to be part of the Severe Accident Program, this issue was raised to ensure continuity in its resolution following the NRC reorganization in April 1987.
B In PWR plants, sodium hydroxide or sodium tetraborate is added to the containment spray or ice condenser solutions.
These chemical additions are required to improve the iodine scrubbing effectiveness of the water / ice solutions and thereby counter a rapid release of large amounts of iodine vapor postulated to result from a severe accident (core-melt).
However, considerably smaller quantities of elemental iodine are now estimated to be released from y
the reactor coolant system much later after an accident.
Consequently, the need for the above chemical additives no longer exists during the injection phase of the spray, but the pH of the containment sump must be above 7 prior to, and during, the rWrculation phase to prevent regeneration of iodine from the containment sump.
BWR plants with suppression pool type containments also have a Standby Gas Treatment System (SGTS) which treats leakage from the containment and removes iodine through adsorption in the charcoal filters.
No credit was previously given for retention of' iodine in the suppression pools.
Relaxation of the chemical additive requirements for PWR containment spray solutions in dr3 containment designs and ice beds in ice condenser containment designs is not expected to result in significant changes in public risk.
For BWRs, any credit given for the suppression scrubbing action should not relax the BWR containment leak rate or change a safety grade system to a non-safety grade system.
Revisions to the SRP11 would eliminate overly conservative assumptions used to estimate the effectiveness of chemical additives to the containment sprays and ice beds.
The affected SRP Sections are 6.5.2 " Containment Spray as a Fission Product Cleanup System," and 6.5.4 " Ice Condenser as a Fission Product Cleanup System." The revisions will affect future PWR plants.
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.In addition, a new SRP12 Section 6.5.5, " Pressure Suppression Pools as Fission Product Cleanup Systers," would provide guidance and review procedures or L
acceptance criteria for the suppression pool retention capabilities and would allow relaxation of maintenance and surveillance of the BWR SGTS and less i
frequent replacement of charcoal media.
The new SRP Section will affect all BWR plants with suppression pool containment designs.
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CONCLUSION The SRP11 revisions discussed above could reduce: (1) the cost of maintenance (including the replacement of chemicals); (2) the cost of surveillance; and (3) the hazard to personnel and equipment from chemical spills or spray initiation.
The new SRP11 Section that would provide allowances for suppression pool retention could result in reduced costs for maintenance (including replacement of charcoal) and surveillance of systems such as the SGTS.
All SRP changes became effective on January 25, 1989.11c2 Thus, the technical concerns of this issue have already been addressed in the Severe Accident Program and Issue 140 will be DROPPED from further consideration as a new and separate issue.
REFERENCES 11.
NUREG-0800, " Standard Review Plcn for the Review of Safety An61ysis Reports for Nuclear Power Plants," U.S. Nuclear Regulatory Commission,
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(10t Edition) November 1975, (2nd Edition) March 1980, (3rd Edition)
July 1981, 1161. Memorandum for K. Kniel from W. Minners, " Proposed Generic Issue -
Fission Product Removal by Containment Sprays or Pools," March 10, 1987.
1162. Federal Register Notice 54 FR 3701, "[NUREG-0800) Standard Review Plan i
for the Review of Safety Analysis Reports for Nuclear Power Plants; Issuance and Availability," January 25, 1989.
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