ML20009F226
| ML20009F226 | |
| Person / Time | |
|---|---|
| Site: | Allens Creek File:Houston Lighting and Power Company icon.png |
| Issue date: | 07/27/1981 |
| From: | Campe K Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20009F186 | List: |
| References | |
| NUDOCS 8107300157 | |
| Download: ML20009F226 (7) | |
Text
<
9 07/27/81 4
UNITED STATES OF AMERICA NdCLEAR REGULATORY COMMISSION BEFORE THE AT0 HIC SAFETY AND LICENSING BOARD In the Matter of
)
)
HOUSTON LIGHTING & POWER COMPANY Docket No. 50-466 (Allens Creek Nuclear Generating
)
Station, Unit 1)
)
NRC STAFF TESTIMONY OF KAZIMIERAS M. CAMPE RELATIVE T0 THE HAZARD 06S MAfERIALS CARRIED ON RAILR0 ADS NEAR THE PROPOSED ALLENS CREEK NUCLEAR PLANT
[ Bishop Contention 17 and McCorkle Contention 9]
Q.
Please state your name and position with the NRC.
A.
by name is Kazimieras M. Campe.
I am employed at the U.S.
Nuclear Regulatory Commission as a Site Analyst in the Siting Analysis Branch.
I have previously testified in this proceeding on aircraft hazaros and natural gas pipeline relocation hazards.
Q.
What is the purpose of this testimony?
A.
The purpose of the testimony is to respond to Bishop Contention 17 and McCorkle Contention 9.
Q.
What does Bishop Contention 17 allege?
A.
Bishop Contention 17 states as follows:
The Applicant has underestimated the adverse impact on the Allens Creek facility of railroad accidents involving the release and/or detonation of train car loads of TNT and other hazardous materials not including chlorine.
8107300157 ajo7p7 '~
Q.
What does McCorkle Contention 9 allege?
A.
McCorkle Contention 9 states as follows:
~
No plan has been developed to protect the plant operators from danger of poisoning from gases such as chlorine which could come into the control room in sufficient quantities to force evacuation before the plant was brought down to low power status.
Railroad accidents and on-site storage of gases such as chlorine could be sources for such gases.
Q.
What sort of adverse effect is associated with the potential detonation of a train car loaded with TNT?
A.
Detonation of any explosive, including TNT, can generate pres-sure waves which emanate in all directions from the point of explosion.
The intensity of a pressure wave, or overpressure, diminishes with dis-tance from the source.
If the overpressure at a given point is greater than the design strength Jf a structure, the structure could be damaged.
Q.
Has the Staff addressed the explosien hazards with respect to the nearby railways?
A.
Yes. We have reported in the Safety Evaluation Report that peak overpressures from postulated explosions of probable maximum cargo of high explosives carried by a railroad box car were found to be much lower than those produced by the design basis tornado. Since the proposed facility is designed to withstand a design basis tornado, we concluded that the overpressure hazard due to potential explosions on the nearby railroads need not be considered 'n the design of the propased facility.
Q.
What is the basis for your conclusion that the potential ex-plosion overpressures would be leis than the design basis overpressure
'or the proposed plant?
l
A.
In our review of the explosion hazards we have postulated up to
~
10 train cars, each loaded with 132,000 pounds of TNT, simultaneously exploding at a point on the Santa Fe railroad, about 4300 feet from the plant. This is an extremely conservative assumption, since it is highly unlikely that more than two or three train cars would be loaded with high explosives on a given train. Only in the case of a rail line servicing a munitions facility would it be reasonable to contemplate anything like ten train cars. Also, it is extremely conservative to assume the simul-taneous explosion of these TNT-loaded train cars. The postulated detona-tion of the 10 train cars of TNT described above would yield a peak positive incident overpressure of about 1 psi at the proposed plant in accordance with the information presented in Regulatory Guide 1.91,
" Evaluations of Explosions Postulated to Occur on Transportation Routes Near Nuclear Power Plants." Since the plant is designed to withstand overpressures in excess of 2.3 psi, this constitutes a basis for r.ot considering tne postulated TNT explosions as a hazard to the plant.
Q.
How many train cars of TNT would have to be detonate 1 in order to exceed the design basis overpressure limit for the proposed plant?
A.
As many as 63 fully loaded train cars. This is based on the relationship between overpressure and scaled ground distance to the source of explosion described in Reference 1 of Regulatory Guide 1.91, Department of the Army Technical Manual TM 5-1300, " Structures to Resist the Effects of Accidental Explosions," June 1969.
Q.
What are your conclusions'regarding the potential effects of postulated explosions of high explosives on the nearby railroads?
I w
. 1 A.
Our findings, as reported in the SER and as described above, indicate that pote s.1 detonations of high explosives do not pose a significant hazard to F;e proposed Allens Creek nuclear power plant.
Q.
What the toxic gas hazards with respect to nearby railroad traffic?
A.
If a freight train carrying hazardous chemicals were involvec in an accident such as a derailment, for example, some of the chemicals may be released or spilled. This could lead to the formation of an airborne toxic gas cloud which may pose a hazard to the plant.
Q.
What are the principal factors which determine the extent of the toxic gas hazard?
A.
The frequency of shipments of hazardous chemicals past the plant site is one of the factors that determines the extent of the hazard.
Shipuents that are infrequent would have a low likelihood of producing spills or releases.
For rail traffic, Regulatory Guide 1.78 indicates that frequencies in excess of 30 shipments per year indicate a need for a detailed review and analysis in order to assess the risk associated with potential toxic gas releases. A number of other factors determine the size and concentration of the toxic gas cloud that could be formed.
These include spill quantity, chemical volatility, ambient temperature, solar heat flux, and windspeed. The level of toxic gas concentration potential reaching the plant is determined by factors such as wind speed, wind direction, and gas buoyancy.. Finally, the potential effects on the control room operators are determ'ihed by the toxic gas concentration within t'.e control room relative to the toxicity of the gas in question.
r Q.
What are the Staff's findings with respect to the toxic gas hazardi steraming from potential railway accidents near the proposed ~
Allens Creek plant?
A.
The Applicant has identified and evaluated the hazards associ-ated with the railway shipment and on-site storage of chlorine. On the basis of its analyses, it has determined that the Allens Creek control room should be designed to accommodate the effects of potential chlorine releases. The Control Room Habitability System design provides for chlorine detectors in the outside air intakes, coupled with automatic isolation of the ventilation system. The control room will be equipped with self contained breathing apparatus for use by the control room operators.
The Staff has have reviewed the proposed Coatrol Room Habitability System design with respect to protection against chlorine and has found that it is within the flRC Standard Review Plan (f c'?EG-75/087) 6.4 criteria and is acceptable.
Specifically, the Applicant has cow 'ted to assuring adequate protection against the potential effects of chlorine by providing the following control room habitability system design and ooeration features, in accordance with SRP 6.4:
1.
Quick acting chlorine gas detectors 2.
Automatic emergency zone isolation 3.
Emergency zone leaktightness 4.
Limited fresh air makeup, rates 5.
Breathingapparatusand$$ssociatedbot*1 Tir supply.
3 in the ACNGS The Applicant's specification of the above fe-PSAR was reviewed by the Staff and was found to he.t tne guidelines of l
Regulatory Guide 1.95, " Protection of Nuclear Power Plant Control Room Operators Against an Accidental Chlorine Release." Hence, we find that in the event of a chlorine release, should the chlorine reach the control room air intakes, the above design features will isolate the control quickly and reliably, such that the control room oprators will have sufficient warning and time to don breathing apparatus and implement a safe shutdown of the plant.
Witn respect to other toxic gases, the Staff is continuing its review. Our earlier reviews of toxic gas hazards due to transportation accidents in the vicinity of nuclear power plants, including the Allens Creek site, were focused primarily on chlorine. More recently, we have expanded our reviews to address other toxic gases.
In particular, we note that the annual production and rail shipment rates of chemicals sucn as ammonia rival those of chlorine. Moreover, the historical record on accidents involving releases of ammonia lead us to believe that ammonia should also be reviewed as a potential hazard.
Production rates of other toxic chemicals such as phogene, hydrogen fluoride, and hydrogen cyanide also suggest that transportation frequencies and quantities could be significant.
In view of the above considerations, we are continuing to review the toxic gas hazards due to potential accidents on the nearby railroads.
Presently, we are anticipating some information to be obtained from the Santa Fe Railroad Company regarding the shipment of hazardous chemicals past the proposed Allens Creek pl' ant.
r i
Q.
Since the Staff review of the toxic gas hazards is still con-tinuing, how does this affect the Staff's conclusions regarding the site suitability for the proposed nuclear plant?
A.
Our fiadings, as reported in the SER, with respect to site suita-bility, are not affected by the ongoing toxic gas review. Hcwever, as noted earlier in my testimony, the Applicant has provided adequate design features for protection against chlorine.
Hence, equipment for automatic control room isolation is already an integral part of the Control Room.
Habitability System design.
Should the need for protection against other gases be identified, appropriate design modifications, such as detectors for the gas in question, cou',d be made. Also, the Staff is currently revising the criteria in Regulatory Guide 1.78 on toxic gas hazards.
Based on more recent information regarding transportation accident rates and severities, improved meteorological models, and better availability on toxicity data, we believe that less restrictive criteria may be adopted.
Thus, the potential number of hazardous chemicals to contend with in any given case is expected to be reduced significantly.
In view of the above considerations, we find it appropriate that the toxic gas hazard evaluation be extended to the Allens Creek Operating Licensing review phase. Due to the relative ease and technical feasibility of providing adequate protecticn against any other potential toxic gas hazard, we find that our evaluation and conclusions regarding the site suitability with respect to the Allens Creek site is not affected.
+
l
-