ML19290F192
| ML19290F192 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 03/06/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 8003180284 | |
| Download: ML19290F192 (1) | |
Text
- pnM%
fg o,j UNITED STATES E'
NUCLEAR REGULATORY COMMISSION e
34 c
REGION I S
631 PARK AVENUE
\\*****[
KtNG OF PRUSSIA, PENNSYLVANIA 1940*
Maren 6, 1980 Docket Nos. 50-245 50-336 Northeast Nuclear Energy Company ATTN:
Mr. W. G. Counsil Vice President - Nuclear Engineering and Operations P. O. Box 270 Hartford, Connecticut 06101 Gentlemen:
The enclosed IE Circular No. 80-03, " Protection from Toxic Gas Hazards", is forwarded to you for information.
No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, m
Boyce H. Grier
" Director
Enclosures:
1.
IE Circular No. 80-03 with Attachments 2.
List of Recently Issued IE Circulars CONTACT:
R. J. Bores (215-337-5260) cc w/encls:
J. F. Opeka, Station Superintendent D. G. Di'edrick, Manager of Quality Assurance J. R. Himmelwright, Licensing Safeguards Engineer 8003 110 E8k
W ENCLOSURE 1 SSINS:
6830 Accession No.:
UNITED STATES 7912190685 NUCLEAR REGULATORY COMMISSION Q
_ f, ll w 0FFICE OF INSPECTION AND ENFORCEMENT p
wj, di 5
WASHINGTON, D.C.
20555 IE Circular No. 80-03 Date:
March 6, 1980 Page 1 of 2 PROTECTION FROM T0XIC GAS HAZARDS Chlorine gas releases have been reported at two different reactor facilities in the past two years.
At Millstone, in March 1978, a leak of about 100 standard cubic feet of chlorine (about a gallon of liquid) occurred over a ten minute period, resulting in the hospitalization of 15 people.
The ventilation system carried the chlorine into the plant buildings, where personnel distress was noted.
No injuries occurred in the buildings due to the small size of the release.
At Browns Ferry, in June 1979, a small leak from a diaphragm on a chlorine reducing valve resulted in the hospitalization of five people, including a control room operator.
Chlorine is highly toxic, producing symptoms after several hours exposure in concentrations of only one ppm.
Concentrations of 50 ppm are dangerous for even short exposures and 1000 ppm is fatal for brief exposures.
- Chlorine, used at some power stations to control organisms in the circulating water, is normally supplied in one ton containers or in tank cars of up to 90 tons capacity.
Other potential sources of toxic gas that have been identified at nuclear power plants include:
Nearby industrial facilities.
At Waterford, in July 1979, construction forces had to be evacuated for two and a half hours due to a chlorine gas release from a nearby chemical plant.
Chlorine transportation on adjacent highways, railways and rivers.
Large tanks of aqueous ammonia stored near plant buildings.
Both acid and caustic storage tanks located in a common building near the control room.
At the Dresden site, in August 1977, accidental mixing of acid and caustic solutions resulted in toxic fumes that entered the control room via the ventilation system.
IE Circular No. 80-03 Date:
March 6, 1980 Page 2 of 2 Criterion 19 of Appendix A to 10 CFR 50 requires a control room from which action can be taken to maintain the reactor in a safe condition under accident conditions.
The control room designs in current license applications are reviewed for operator protection from toxic gases (as well as radiation), in accordance with Standard Review Plan (SRP) 6.4 (NUREG 75/087 dated 11/24/75).
Related information on the identification of potential hazards and the evalua-tion of potential accidents can be found in SRP sections 2.2.1-2.2.2 and 2.2.3 respectively.
The SRP references Regulatory Guide 1.78 (dated June 1974) on control room habitability during chemical releases.
It also references Regula-tory Guide 1.95 on requirements for protection against chlorine releases specifically.
The majority of the plants currently operating, however, were built and licensed prior to the development and implementation of this guidance.
A review of some older plants, with respect to toxic gas hazards indicates that they do not have the degree of protection that would be required for present day plants.
Evaluation of the protection of control rooms from toxic gas releases is part of the systematic evaluation program currently being carried out on certain older plants.
Also, as older facilities submit requests for significant license amendments, their design features and controls for protection of control rooms are reviewed and, if appropriate, are required to be changed.
However, the recent history of frequent toxic gas release incidents appears to warrant a more rapid implementation of the newer toxic gas protection policies.
For the above reasens, it is strongly reccmmended that:
You evaluate 2 -
plant (s) against section 6.4 and applicable parts of sections 2.2.1-2.2.2 and 2.2.3 of the SRP with respect to toxic gas hazards.
Where the degree of protection against toxic gas hazards is found to be significantly less than that specified in the SRP, provide the controls or propose the design changes necessary to achieve an equivalent level of protection.
No written response to this circular is required.
If you desire additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
Attachments:
Sections 2.2.1-2.2.2; 2.2.3 and 6.4 of NUREG 75/087
Attacf1 ment to IE Circular No. 80-03 na arc NU REG.75/087
.e oN j'
U.S. NUCLEAR REGULATORY COMMISSION g
i STANDARD REVIEW PLAN
\\.....
OFFICE OF NUCLEAR REACTOR REGULATION SECTIONS 2.2.1 - 2.2.2 IDENTIFICATION OF POTENTIAL HAZARDS IN SITE VICINITY l
REVIEW RESPONSIBILITIES Primary - Accident Analysis Branch (AAB)
Secondary - None I.
AREAS CF REVIEW
. Locations and separation distances frcm the site of industrial, military, and transportation facilities and routes in the vicinity of the site. Such facilities and routes include air, ground, and water traffic, pipelines, and fixed manufacturing, processing, and storage facilities. Potential external hazards or hazardous materials that are present or whien may reasonably be expected to be present during the projected life time of the proposed plant. The purpose of this review is to establish the information concerning the presence of potential external ha:ards which is to be used in further review in Sections 2.2.3, 3.5.1.5, and 3.5.l.6.
II. ACCEPTANCE CRITERIA 1.
Data in the SAR adequately describes the locations and distances of taustrial, l
military, and transportation facilities in the vicinity of the plant, and is in agreement with data obtained from other sources, when available.
2.
Descriptions of the nature and extent of activities conducted at nearoy facilities, including the products and materials likely to be processed, stored, used, or trans-ported, are adequate to permit evaluations of possible hazards in Part 3 review sections dealing.with specific hazards.
3.
Where potentially hazardous materials may be processed, stored, used, or transported in the vicinity of the plant, sufficient statistical data on such materials are l
provided to establish a basis for evaluating tne potential hazard to the plant.
III. REVIEW pe0CEDURES Selection and empnasis of varicus aspects of the areas covered by this review plan will be made by the reviewer on each case. The judgment of the areas to be given attention during the review is to be based on an inspection of the material presented, the similarity of the material to that recently reviewed on otner plants, and whether itens of special safety significance are involved. The following procedures are fellcwed:
l USNRC DUPLICATE DOCUMENT
- " '.', Z.*.~**n~'.'.". %...a C."U
~ **
{ Q -
h,- [ *,,,,
Entire docement previous 1y entered inta system under:
.w-ANO e
a.= w - -.-
. - o e ma No. of pages:
Attachment to IE Circular No. 80-03
~.
n atog'o NUREG 75/087 e
f, g {',g U.S. NUCLEAR REGULATORY COMMISSION MQf !
STANDARD REVEW PLAN
\\..... #
OFFICE OF NUCLEAR REACTOR REGULATION SECTICN 2.2.3 EVALUATICN OF POTENTIAL ACCIDENTS REVIEW RESPONSIBILITIES Primary - Accident Analysis Branch (AAB)
Secondary - Aoplied Statistics Branch (ASS /MPA)
I.
AREAS OF REVIEW The applicant's identification of potential accident situations in the vicinity of the plant is reviewed to determine the C0mpleteness of and the bases upon which these potential accidents were er were not acccernodated in the design. (See Standarc Review Plans 2.2.1 and 2.2.2.)
The applicant's probability analyses o' potential accidents involving hazardous materials or activities in the vicinity of the plant, if such analyses have been perforted, are also reviewed by ASS /MPA on request by AAB to determine that appropriate data and analytical models have been utiliced.
The analyses of the consecuences of accidents involving nearby industrial, military, and transportation facilities which have been identified as design basis events are reviewed.
II. ACCEPTANCE CRITERIA The identification of design basis events 7sulting from the presence of hazardous materials or activities in the vicinity of the plant is acceptable if the design basis events include eacn postulated type of accident for which the expected rate of occurrence of potential l
exposures in excess of the 10 CFR Part 100 guidelines is estimated to exceed the NRC staff objective of approximately 10 per year. Because of the difficulty of assigning accurate numerical values to the expected rate of unprecedented potential hazards generally con-sidered in this review plan, judgment must be used as to the acceptability of the overall risk presented.
The prceability of occurrence of the initiating events leaeing to potential consequences in excess of 10 CFR Part 100 exposure guidelines should be estimated using assumptions that are as representative of the specific site as is practicable. In, addition, because of the Icw probabilities of the events under censidar3 tion, data are of ten not available to pemit accurate ca:culation of probabilities. Acccedingly, the expected rate of occur-rence of potential exposures in excess of the 10 CFR Part 100 guidelines of approximately 10 per year is acceptable if, when combined with reasonable qualitative arguments, the realistic probability can be shown to be 1cwer.
USNRC STAND ARD REVIEW PLAN sta.m e, r.t.80 B..d n..,
twin..
..er cee...em
.. i..
t neee ew1a.,
.e
.nem e..
t
.w.f 34.Rt. Th wm.mt..t.m....w.s6
- 0. to tM..wWe.
.f th. C.mme..e.n..eep.y t. me.e.e tM. swe..r Is.wMry.nd tee n,
is.r.d Th. m
.u.
4.e qt n.
..we f
F.
C.pg.ng. 34 yA e.
ege6 e
.,e t.
.t....
~
.w.sh.h.d Hand.rd e.ue.w d.st. e.G be t e..d.em.de.asfy,..
r n.v., t.
.mm.det. s.mm.s.t..nd t. e t 4.u. enf.rsegetsee.ed e.g.n.p.e
=. =-,. w.m m
MUV1
~]9(M(Q(pg$$'
Attachment to IE Circular No. 80-03
. ~..
The effects of design basis events have been adecuately considered if analyses of the l
effects of those accidents on the safety-related features of the plant have been perforr" N
and measures (e.g., hardening, fire protection) to mitigate the consequences of such events bsve been taken.
III. REVIEW PROCEDURES In some cases it may be necessary to consult with or obtain specific data from other branches, such as the Structural Engineering Branch (SEB) or Auxiliary Systems Branch l
(ASB), regarding possible effects of external events on plant structures or components.
The applicant's probability calculations are reviewed, and an independent probability aatlysis is performed by the staff if the potential hazard is considered significant enough to affect the licensability of the site or is important to the identification of design basis events.
All stochastic variables that affect the occurrence or severity of the postulated event are identified, and judged to be either independent er conditioned by other variables.
Probabilistic models should be tested, where possible, against all available infomation.
If the model or any portion of it, by simple extension, can be used to predict an observ-able accident rate, this test should be perfcmed.
The design parameters (e.g., overpressure) and physical phenomena (e.g., gas concentration) selected by the applicant for each design basis event are reviewed to ascertain that the values are comparable to the values used in previous analyses and found to be acceptable by the staff.
Each design basis event is reviewed to determine that the effects of the event on the safety features of the plant have been adequately accornodated in the design.
If accidents involving release of smoke, flammable or nonflammable gases, or chemical bearing clouds are considered to be design basis events, an evaluation of the effects of these accidents on control room habitability should be made in SAR Section 6.4 and on the operation of diesels and other safety-related equipment in SAR Chapter 9.
Special attention should be given to the review of standardized designs which propose criteria involving individual numerical probability criteria for individual classes of external man-made hazards. In such instances the reviewer should establish that the envelope also includes an overall criterion that limits the aggregate probability of exceed-ing design criteria associated with all of the identified external man-made hazards.
Similarly, special attention should be given to the review of a site where several man-made hazards are identified, but none of which, individually, has a probability exceeding the acceptance cc,1teria stated herein. The objective of this special review should be to assure that the aggregate probability of an outcome that may lead to unacceotable plant damage meets the acceptance criteria of Part II of this SRP Section. (A hypothetical example is a situation where the probability of shock wave overpressure greater than design Rev. 1 2.2.3-2
Attachment to IE Circular No. 80-03 overpressure is about 10' per reactor year from accidents at a nearby industrial facility, and approximately equal probabilities of exceeding design pressure from railway accidents, highway accidents and from shipping accidents. Individually each may be judged acceptably low; the aggregate probability may be judged sufficiently great that additional features of design are warranted.)
IV. EVALUATION FINDIN"5 If the reviewer verifies that sufficient infcrmation has been provided and that his evaluation is sufficiently complete and adequate to meet the acceptance criteria in Section II of this SRP, conclusions of the following type may be prepared for the staff's. safety evaluation report:
"The applicant has identified potential accidents which could occur in the vicinity of the plant, and from these has selected those which should be censidered as design l
basis events and has provided analyses of the effectc of these accidents on the safety-related features of the plant. The applicant has demonstrated that the plant is adequately protected and can be operated with an acceptable degree of safety with i
regard to potential accidents which may occur as the result of activities at nearby industrial, military, and transportation facilities."
V.
REFERENCES Regulatory Guide 1.70, " Standard Fomat and Content of Safety Analysis Reports for Nuclear Power Plants," Revision 2.
t Affidavit of Jacques B. J. Read before the Atomic Safety and Licensing Board in the matter of Skagit Nuclear Power Project, Units 1 and 2 July 15,1976. Docket Nos. STN 50-522, 523.
Atomic Safety and Licensing Board, Supplemental Initial Decision in the Matter of Hope Creek Generating Station, Units 1 and 2. March 23,1977. Docket Nos. 50-354, 355.
Section 2 Supplement 2 to the Floating Nuclear Plant Safety Evaluation Report, Docket No. STN 50-437, September 1976.
2.2.3-3 Rev. I
Attachment to IE Circular No. 80-03 a
NUREG 75/087 l n asog*o WCp{',g f])g U.S. NUCLEAR REGUI.ATORY COMMISSION STANDARD REVIEW Pl.AN OFFICE OF NUCLEAR REACTOR REGULATION SECTION 6.4 HABITABILITY SYSTEMS REVIEW RESPONSIBILITIES Primary - Accident Analysis Branch (AA8)
Secondary - Hydrology-Meteorology Branch (HPS)
Auxiliary Systems Branch (ASB)
Effluent Treatment Systems Branch (ETSB)
I.
AREAS OF REVIEW The control room ventilation system and control building layout and structures, as described in the applicant's safety analysis report (SAR). are reviewed with the objective of assuring that plant operators are acequately protected against the effects of accidental releases of toxic or radioactive gases. A further objective is to assure that the control room cari be maintained as the center from.hich emergency teams can safely operate in the case of a design basis radiological release. To assure that these objectives are accom-plished the folicwing items are revieweo:
1.
The zone serviced by the control room emergency ventilation system is examined to ascertain that all critical areas requiring access in the event of an accident are included within the zone (control room, kitchen, sanitary facilities, etc.) and to l
assure that those areas not requiring access are generally excluded from the zone.
2.
The capacity of the control room in terms of the number of people it can accommodate for an extended period of time is reviewed to confirm the adequacy of emergency food and medical suoplies and self-contained breathing apparatus and to determine the length of time the control room can be isolated before CO levels become excessive.
2 3.
The control room ventilation system layout and functional design is reviewed to determine flow rates and filter efficiencies for incut into the AA8 analyses of the buildup of radioactive or toxic gases inside the control room, assuming a design basis release. Basic deficiencies that mignt imoair the effectiveness of the system are examined. In addition, the system operation and procedures are reviewed. The ASB has primary responsibility 'n the system review area under Standard Review Plan (SRP) 9.4.1.
The ASB is consulted when reviewing hardware and operating procedures.
DUPLICATE DOCUMENT USNRC STAN pgyiously Entire document
,. mm n.
... o....
into Ys em unde entere
_U ".' O **.' Z.*.'.*.T *'.".'.">.*** TS*"*'*.C.*m*
((
m..
3NO
,(
r-.-,..
N o. of PacJes:
c-~.
1 6 4. W g. O.o. xX' E