NUREG/CR-3551, Forwards Comments on NUREG/CR-3551, Safety Implications Associated W/In-Plant Pressurized Gas Storage & Distribution Sys in Nuclear Power Plants
| ML20136G557 | |
| Person / Time | |
|---|---|
| Issue date: | 08/06/1985 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| References | |
| RTR-NUREG-CR-3551 NUDOCS 8508190550 | |
| Download: ML20136G557 (2) | |
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\ C. J. Heltemes, Jr., Director l MEMORANDUM FOR:
Office for Analysis and Evaluation of Operational Data FROM: Harold R. Denton, Director Office of Nuclear Reactor Regulation
SUBJECT:
COMMENTS ON THE FINAL CASE STUDY REPORT, " SAFETY IMPLICATIONS ASSOCIATED WITH IN-PLANT PRESSURIZED GAS STORAGE AND DISTRIBUTION SYSTEMS IN NUCLEAR POWER PLANTS," NUREG/CR-3551, ORNL/NSIC 214, ITEMS 10.1, 10.2, AND 10.3 As requested by your memorandum of June 13, 1985, NRR has reviewed the subject final case study report and comments regarding Sections 10.1, and 10.2,10.3 are enclosed.
It is our understanding that the Office of Inspection and Enforcement is considering an Information Notice for the purpose of disseminating the suggested methods of implementing the recommendations outlined in Section 10.1.
If you have any questions regarding this memorandum, please feel free to contact D. Tarnoff at 492-9526.
N/
Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosure:
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. MEMORANDUM FOR: C. J. Heltemes, Jr. , Director Office for Analysis and Evaluation of Operational Data FROM: Harold R. Denton, Director Office of Nuclear Reactor Regulation -
1
SUBJECT:
COMMENTS ON THE FINAL CASE STUDY REPORT, " SAFETY I IMPLICATIONS ASSOCIATED WITH IN-PLANT PRESSURIZED GAS STORAGE AND DISTRIBUTION SYSTEMS IN NUCLEAR POWER PLANTS," NUREG/CR-3551, ORNL/NSIC 214, ITEMS 10.1, 10.2, AND 10.3 As requested by your memorandum of June 13, 1985, NRR has reviewed the subject final case study report and comments regarding Sections 10.1, and 10.2,10.3 are enclosed.
It is our understanding that the Office of Inspection and Enfcrcement is considering an Information Notice for the purpose of disseminating the suggested methods of implementing the recommendations outlined in Section 10.1.
If you have any questions regarding this memorandum, please feel free to contact D. Tarnoff at 492-9526.
n/
Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosure:
cc: R. Colmar As stated T. Speis DISTRIBUTION Central File w/inc. Marie /HThompson (859147)
NRC PDR w/inc. Connie /DCrutchfield (859147)
NSIC w/inc. RWessman Denton/Eisenhut DTarnoff PPAS GHolahan ORAB Rdg HSmith (859147) (f[2//[
- PREVIOUS CONCURRENCE SEE DATE ORAB:DL* SL:0RAB:DL* C:0RAB:DL* AD/SA:DL* AD/ TECH
- DTarnoff:cl RWessman GHolahan DCrutchfield FRowsome 7/24/85 7/25/85 7/25/85 7/25/85 7/26/85 D/DL* D [,/NQ HThompson en n 7/31/85 /85 /{/85
SAFETY PROGRAM EVALUATION BRANCH COMMENTS ON THE AE00 MEMORANDUM FROM C. J. HELTEMES, JUNE 13, 1985 TRANSMITTING AE00/C501/
NUREG/CR-3551, ORNL/NOAC 214, " SAFETY IMPLICATIONS ASSOCIATED WITH IN-PLANT PRESSURIZED GAS STORAGE AND DISTRIBUTIONS SYSTEMS IN NUCLEAR POWER PLANTS," MAY 1985
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The following comments on the memo from C. J. Heltemes, June 13, 1985, transmitting the final report of NUREG/CR-3551 specifically address Sections 10.1, 10.2, and 10.3 of the subject report, as requested in the Heltemes memo.
I Section 10.1, Gas Cylinder Missiles.
In our review of the pertinent sections of the report on the potential and possible consequences of a portable gas cylinder accidentally becoming l a missile we note that these discussions were general and anecdotal in natitre and with no clear basis established to suggest that a significant j safety concern exists in nuclear power plants. For example, several instances were cited wherein gas cylinders became missiles accidentally but i virtually all of these were limited to non-nuclear installations; only one instance was cited for a nuclear plant (North Anna) in which a gas cylinder became a missile, but e.e in this case no safety-related damage was reported. The existence of a safety concern appears to be speculative as the authors of the report did not attempt to construct a simple risk analysis from the available information with which to demonstrate that there is a reasonable expectation that a real problem may exist in nuclear power plants.
On the contrary, the authors appear to leave this to be inferred but, on the i
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other hand, have tacitly suggested that the problem is a relatively minor one in nuclear plants by stating (page 53) that, "... Reported instances relating to compressed gases are rare in nuclear plants, indicating that the nuclear industry is generally using. safe practices and following recommended safety rules...". Only two instances were noted by the authors in which NRC inspectors indicated that nuclear plant practices were somewhat lacking in
- this regard. Moreover, the authors also stated (page 54) that, "No problems were found with in plant portable gas cylinder storage facilities.
Cylinders were capped, secured, identified, and segregated. Also, all cylinder manifolds appeared to be adequately designed and properly maintained. Except for one acetylene cylinder, all gas cylinders being used in the plant were properly secured..." On the basis of these assertions by the authors and in the absence of any applied analysis and evaluation of the available information for a nuclear site, it appears that the authors' recommendations are based primarily on speculation.
In our previous memo of January 11, 1985, on the review of the draft of the subject report we noted that the main emphasis in protecting against the development of missiles from damaged gas cylinders should be placed on improving administrative controls that includes training, handling procedures, and equipment inspections. Based on the industry experience noted so far, as cited in the subject report, it would appear that these administrative controls at nuclear plants are already adequate at their present levels. Therefore, we reaffirm our previous view, as expressed in
the January 11, 1985 memo, that no changes to SRP Section 3.5.1.1 dnd 3.5.1.2 appear to be warranted at this time.
Section 10.2, Hydrogen Explosions The suggested method of implementation for the recommendation of this section in the subject report is to revise SRP 9.5.1, " Fire Protection Program," in order to require excess-flow valves in all hydrogen lines that enter areas containing or close to safety-related equipment. As noted in the subject report SRP 9.5.1, revisions 2 and 3 of July 1981, presently includes the following requirements under " Control of Combustibles";
" Hydrogen lines in safety-related areas should be either designed to seismic Class I requirements, or sleeved such that the water pipe is directly vented to the outside, or should be equipped with excess-flow valves so that in case of a line break, the hydrogen concentration in the affected areas will not exceed 2%".
It is not clear from the contents of the subject report that the other options presently provided for in the SRP Section 9.5.1 do not offer equally adequate protection against hydrogen fires and explosions. Moreover, it is to be noted that of the options presently available in the SRP Section 9.5.1, the option to install flow-limiting valves is by far the least expensive and would, therefore, appear to be the most likely option of choice. In any
case, it is not evident that a basis exists in the subject report to limit the SRP to the single option of excess-flow valves. Therefore, we do not anticipate any changes to the present version of SRP Section 9.5.1, " Fire Protection Program." Safety Program Evaluation Branch is presently prioritizing the matter of backfitting SRP Section 9.5.1 using the least expensive method, which is to install excess-flow valves on the hydrogen lines in operating plants. This effort has been identified as safety issue No.106, " Piping and the Use of Highly Combustible Gases in Vital Areas".
Sect on 10.3, Identification of Lines and Tanks.
Within the scope of the present SRP Sections 2.2.1, 2.2.2, 2.2.3, and 6.4, NRC reviews cover significant portions of the nuclear power plant site in terms of protection from the effects of toxic and otherwise hazardous materials and gases. This includes the hazards external to the plant site and the control room as well as bulk quantities of such materials that may be on-site. The results of these reviews are such that the licensee is required to make provisions which will preclude any adverse effect on safety related systems in the event of an accident. These provisions are, therefore, more far-reaching than simple identification of lines and tanks so that for those portions of the plant.already covered by these SRP sections the identification of lines and tanks is essentially unnecessary from the standpoint of possible impairment of safety-related equipment and potential radiological releases to the public.
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For the remaining areas of the nuclear power plant site, which contain relatively small lines and small quantities of potentially hazardous materials and gases, the authors of the subject report have not demonstrated how the identification of lines and tanks will significantly affect core melt frequencies and/or radiological releases that may affect the health and safety of the public. Such potentially hazardous materials can be a source of concern in terms of industrial accidents involving plant operators and personnel but these represent nonradiological episodes. The authors of the subject report have presented as a basis for their recommendation in this matter the somewhat vague generalization that, "A misidentification could cause a hazardous condition." But this has not been amplified to demonstrate, by some simple risk analysis, that the hazardous condition goes beyond industrial accidents to potential radiological releases threatening the health and safety of the public. Without such a demonstration it is not likely that the NRC would have the proper authority to regulate those matters limited to industrial accidents arising from nonradiological sources and not having radiological consequences.